Inspection apparatus and method of inspection

An inspection apparatus includes a liquid discharge head and a first light source. The liquid discharge head is configured to discharge a transparent liquid onto a discharged object. The first light source is configured to irradiate a pattern formed by the transparent liquid discharged onto the discharged object with light having a single peak wavelength to cause a difference between brightness and darkness.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority under 35 U.S.C. § 119 to Japanese Patent Application No. 2016-024723, filed Feb. 12, 2016 and Japanese Patent Application No. 2016-248321, filed Dec. 21, 2016. The contents of which are incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an inspection apparatus and a method of inspection.

2. Description of the Related Art

Conventionally, in apparatuses that discharge liquids such as inkjet recording apparatuses, it is difficult to perform the discharge detection of transparent liquids, and a method that discharges transparent liquids onto colored liquids is employed. Examples of peripheral techniques related to this method include “a printing apparatus and a method of printing” that can form a print pattern suitable for registration adjustment (refer to Japanese Unexamined Patent Application Publication No. 2000-141624).

This technique according to Japanese Unexamined Patent Application Publication No. 2000-141624 shifts the drive timing of a plurality of groups of print elements to print a print pattern that changes in the color of the overlapped parts of a plurality of basic print patterns.

However, as disclosed in Japanese Unexamined Patent Application Publication No. 2000-141624, when a streak occurs in an object solidly printed with a colored ink by nozzle omission or bent discharge, it is difficult to perform the discharge detection of a transparent ink printed on the streak.

SUMMARY OF THE INVENTION

According to an embodiment, an inspection apparatus includes a liquid discharge head and a first light source. The liquid discharge head is configured to discharge a transparent liquid onto a discharged object. The first light source is configured to irradiate a pattern formed by the transparent liquid discharged onto the discharged object with light having a single peak wavelength to cause a difference between brightness and darkness.

DESCRIPTION OF THE EMBODIMENTS

An object of an embodiment is to provide an inspection apparatus and a method of inspection that can appropriately detect the faulty discharge of a liquid discharge head that discharges a transparent liquid onto a discharged object.

FIG. 1is a schematic side view of an example of an image forming apparatus100that includes an inspection apparatus according to the embodiment of the present invention and performs image formation on a discharged object to be inspected. The present embodiment will be described assuming that a liquid discharge head is a recording head or an ink head that discharges ink droplets of four colors of black K, cyan C, magenta M, and yellow Y or a transparent posttreatment liquid onto a recording medium as the discharged object. In this regard, other than that, the liquid discharge head may be a configuration of a type handling green G, red R, and light cyan LC, a type corresponding to other colors, or a type handling only black K.

Although the present embodiment assumes a case using rolled paper Md that is continuous stationery wound in a rolled manner as the recording medium to be the discharged object, the recording medium is not limited to the continuous stationery. In other words, the recording medium that can form images using the image forming apparatus includes cut paper, plain paper, high-quality paper, thin paper, thick paper, recording paper, a transparency, a synthetic resin film, a metallic thin film, and other sheet members that can form images thereon with inks or the like. For information, the rolled paper in this example is continuous stationery indicating continuous form paper or a continuous form.

Referring toFIG. 1, the image forming apparatus100includes a feeder10that feeds the rolled paper Md, a pretreatment unit20that pretreats the fed rolled paper Md, and a drying unit30that dries the pretreated rolled paper Md. The image forming apparatus100also includes an image forming unit40that forms images on the surface of the rolled paper Md, a posttreatment unit50that posttreats the image-formed rolled paper Md, and a carry-out unit60that carries out the posttreated rolled paper Md. The image forming unit40, the posttreatment unit50, and maintenance-and-restoration units90A and90B are arranged on a casing74of a printer engine72E. The casing74as an inkjet printer main body includes a conveying unit80including a conveying belt. A scanner101provided on the downstream side of the drying unit30forms an inspection apparatus that automatically inspects a discharge detection pattern image-formed on the rolled paper Md together with discharge heads provided in the image forming unit40and the posttreatment unit50. A light source held by an inspection stage through an illumination mounting tool including an illumination operating unit as a separate configuration from the image forming apparatus100also forms an inspection apparatus that visually inspects the discharge detection pattern together with the discharge heads similarly. These inspection apparatuses will be described below in detail including their detailed configurations.

The image forming unit40, the posttreatment unit50, the maintenance-and-restoration units90A and90B, a casing73, the casing74, and a drying unit32for posttreatment correspond to the printer engine72E. The image forming apparatus100further includes a controller70that controls the operation of the apparatus as described below with reference toFIG. 11.

The image forming apparatus100according to the present embodiment feeds the rolled paper Md by the feeder10and pretreats and dries the surface of the rolled paper Md by the pretreatment unit20and the drying unit30. The image forming apparatus100forms images on the surface of the rolled paper Md after being pretreated and dried by the image forming unit40. Further, the image forming apparatus100in the present embodiment posttreats the image-formed rolled paper Md by the posttreatment unit50. Subsequently, the image forming apparatus100winds the rolled paper Md by the carry-out unit60and discharges or carries out the rolled paper Md to the outside of the apparatus.

The following specifically describes the components of the image forming apparatus100. The image forming apparatus100itself can be a configuration that does not include any one or more of the pretreatment unit20and the like described below in accordance with the type of the recording medium on which an image will be formed.

The feeder10is a unit that conveys the recording medium to the pretreatment unit20and the like. The feeder10in the present embodiment includes a paper feeding unit11and a plurality of conveying rollers12. The feeder10feeds and moves the rolled paper Md held by being wound around a paper feeding roll of the paper feeding unit11using the conveying rollers12and the like to convey the rolled paper Md to the pretreatment unit20and the like described below using a platen and the like.

The pretreatment unit20is a unit that treats the recording medium before the image is formed and in the present embodiment pretreats the surface of the rolled paper Md fed by the feeder10with a pretreatment liquid. In this example, the pretreatment is treatment that uniformly applies the pretreatment liquid having a function of flocculating an ink to the surface of the rolled paper Md. With this treatment, when an image is formed on a recording medium that is paper for inkjet exclusive use or other than the paper for inkjet exclusive use, the image forming apparatus100can apply the pretreatment liquid having the function of flocculating the ink to the surface of the recording medium using the pretreatment unit20before forming the image on the recording medium.

Consequently, the image forming apparatus100can reduce the occurrence of quality problems such as the blur, the density, the tone, and the set-off of the formed image and problems concerning waterproofness, weatherproofness, and other image robustness. Consequently, the quality of an image to be formed subsequently can be improved.

FIG. 2is a schematic configuration diagram of an example of the pretreatment unit20of the image forming apparatus100. The following describes an example using roll coating as the pretreatment unit20. As illustrated inFIG. 2, the pretreatment unit20in the present embodiment applies a stored pretreatment liquid20L to the surface of the rolled paper Md fed into the pretreatment unit20by the feeder10.

Specifically, the pretreatment unit20first moves and transfers the pretreatment liquid20L to the surface of an application roller23in a thin film shape by a stirring roller21for supply and a thin film forming roller22for transfer. Next, the pretreatment unit20presses the application roller23against a rotating platen roller24to rotate the application roller23. In this process, the pretreatment unit20conveys the rolled paper Md to a gap between the application roller23and the platen roller24, thereby applying the pretreatment liquid20L to the surface of the rolled paper Md.

The pretreatment unit20controls at least either of nip pressure indicating pressure acting on a position at which the application roller23and the platen roller24come into contact with each other or the rotation speed of the application roller23and the platen roller24when the pretreatment liquid20L is applied using a pressure adjustment apparatus25. With this control, the pretreatment unit20changes the nip pressure using the pressure adjustment apparatus25while changing the rotation speed of the application roller23and the like, whereby the film thickness, the liquid amount, the adhesion amount, and the application amount such as a dried adhesion amount of the pretreatment liquid20L can be changed and controlled. Consequently, the pretreatment liquid20L can be applied to the surface of the rolled paper Md with an application amount appropriate for the subsequent image formation and posttreatment.

The drying unit30is a unit that dries the recording medium by heating or the like. In the present embodiment, the drying unit30includes a drying unit31for pretreatment that dries the rolled paper Md pretreated by the pretreatment unit20and a drying unit32for posttreatment that dries the rolled paper Md posttreated by the posttreatment unit50.

For the drying unit31for pretreatment, heat rollers311to316can be used, for example, as described below with reference toFIG. 3. Specifically, the drying unit31for pretreatment heats the heat rollers311to316up to 40° C. to 110° C., for example, thereby causing the surface of the rolled paper Md to which the pretreatment liquid20L has been applied to be in contact or the like with the heat rollers311to316. With this operation, the drying unit31for pretreatment can heat the surface of the rolled paper Md to which the pretreatment liquid20L has been applied by the heat rollers311to316, evaporate water in the pretreatment liquid20L, and dry the pretreatment liquid20L on the rolled paper Md.

FIG. 3is a schematic configuration diagram illustrating an example of the drying unit30of the image forming apparatus100. In the drying unit31for pretreatment of the drying unit30, the heat rollers311to316are preferably provided in a multistage manner as illustrated inFIG. 3in order to enhance a drying effect. When drying intensity is weakened in such a configuration, a heat roller temperature is decreased. The heat roller temperature may be about 40° C. to 80° C., for example. Further, only the heat rollers311and312are heated, for example, whereas the other heat rollers313to316are not heated, for example. In contrast, the number of the heat rollers used or the heat roller temperature is increased, whereby the drying intensity can be enhanced.

For information, although an example in which the heat roller temperature and the number of the heat rollers used are controlled has been described in this example, even only either of them can control the drying intensity. Thus, a combination of the heat roller temperature and the number of the heat rollers used can control the drying intensity.

The drying unit31for pretreatment of the drying unit30is not limited to the heat rollers311to316. In other words, for the drying unit31for pretreatment, infrared drying, microwave drying, hot-air drying, and other drying techniques can be used. For the drying unit31for pretreatment, a drying technique obtained by combining a plurality of drying techniques may be used. Further, for the drying unit31for pretreatment, as a preheating process, the rolled paper Md may be heated before the pretreatment unit20applies the pretreatment liquid20L.

The configuration of the drying unit32for posttreatment is similar to the configuration of the drying unit31for pretreatment, and a description thereof is omitted.

The image forming unit40is a unit that forms images on the rolled paper Md as the recording medium. The image forming unit40in the present embodiment discharges ink droplets onto the rolled paper Md dried by the drying unit30to form images on the surface of the rolled paper Md.

FIGS. 4A and 4Bare illustrative diagrams illustrating a case in which a full-line type liquid discharge head is used as an example of the image forming unit40and a posttreatment liquid discharge unit of the image forming apparatus100.FIG. 4Ais a schematic plan view illustrating an arrangement configuration of the entire image forming unit40, andFIG. 4Bis a schematic plan view illustrating the main part of the image forming unit40in an enlarged view.

As illustrated inFIG. 4A, for the image forming unit40in the present embodiment, the full-line type liquid discharge head can be used. In other words, the image forming unit40arranges four discharge heads40K,40C,40M, and40Y corresponding to black K, cyan C, magenta M, and yellow Y, respectively, from the upstream side in a conveyance direction Xm of the rolled paper Md as the recording medium.

InFIG. 4A, the discharge head40K of black K in the present embodiment arranges four head units40K-1,40K-2,40K-3, and40K-4in a staggered manner in a direction orthogonal to the conveyance direction Xm of the rolled paper Md. With this arrangement, the image forming unit40can form images in the entire area in the width direction as the direction orthogonal to the conveyance direction Xm in an image forming area as a print area of the rolled paper Md. The rolled paper Md is conveyed in the conveyance direction Xm by a conveying belt81, and the head units40K-1,40K-2,40K-3, and40K-4move relative to the rolled paper Md in a direction opposite to its conveyance direction Xm. The configurations of the other discharge heads40C,40M, and40Y are similar to the configuration of the discharge head40K of black K, and descriptions thereof are omitted.

FIG. 4Bis an enlarged plan view of the head unit40K-1of the discharge head40K of black K of the image forming unit40. The head unit40K-1in the present embodiment includes a plurality of discharge ports40N on a nozzle face corresponding to an outer surface of a nozzle plate43inFIG. 5Adescribed below. The discharge ports40N correspond to nozzles or print nozzles and are arranged in a row in the longitudinal direction of the head unit40K-1to form a nozzle row. The head unit40K-1may include a plurality of nozzle rows. Although the example inFIG. 4Aforms a liquid discharge head that has two nozzle rows and discharges droplets of one line by two adjacent head units, the liquid discharge head may have other shapes; the liquid discharge head may be configured by connecting a plurality of head units and arranging them in a row, or the liquid discharge head may have a configuration in which one head unit in which one line extending in the width direction of the rolled paper Md corresponds to one nozzle corresponds to one head, for example. For information,FIG. 4Aalso illustrates a discharge head50H of the posttreatment unit50described below.

The discharge heads40K,40C,40M, and40Y are mounted on a carriage46described below with reference toFIG. 7to be a first discharge unit discharging colored ink droplets.

FIGS. 5A and 5Bare schematic sectional views illustrating an example of the image forming unit40and the posttreatment liquid discharge unit of the image forming apparatus100.FIG. 5Ais a longitudinal sectional view of a liquid chamber40F of a liquid discharge head, andFIG. 5Bis a transverse sectional view of the liquid chamber40F of the liquid discharge head in the SC1-SC1direction inFIG. 5Aindicating the arrangement direction of the discharge ports40N.

Referring toFIG. 5A, the discharge head40K as one of the liquid discharge heads of the image forming unit40according to the embodiment of the present invention includes a channel plate41forming a channel for an ink to be discharged and a vibration plate42connected to a lower face of the channel plate41in an inner direction of the discharge head40K. The discharge head40K also includes a nozzle plate43connected to an upper face of the channel plate41in an outer direction of the discharge head40K and a frame member44holding a peripheral part of the vibration plate42. The discharge head40K includes a pressure generating unit45by an actuator unit for deforming the vibration plate42.

The discharge head40K according to the present embodiment stacks the channel plate41, the vibration plate42, and the nozzle plate43, thereby forming a nozzle communication channel40R as a channel to communicate with the discharge port40N of the nozzle and the liquid chamber40F. The discharge head40K further stacks the frame member44, thereby forming an ink inflow port40S for supplying the ink to the liquid chamber40F, a common liquid chamber40D that supplies the ink to the liquid chamber40F, and the like.

Further, the discharge head40K can bend the vibration plate42using the pressure generating unit45. With this bending, the discharge head40K can change the volume of the liquid chamber40F and change pressure acting on the ink within the liquid chamber40F. Consequently, the discharge head40K can discharge the ink from the discharge port40N.

In addition, the frame member44in the present embodiment is formed with a housing part that houses the pressure generating unit45, a recess to be the common liquid chamber40D, and an ink supply port40IN for supplying the ink to the common liquid chamber40D from the outside of the discharge head.

For the pressure generating unit45, electromechanical transducer elements can be used. The pressure generating unit45in the present embodiment includes piezoelectric elements45P as the electromechanical transducer elements, a base substrate45B that connects and fixes the piezoelectric elements45P, and supports arranged in gaps between adjacent piezoelectric elements45P. The pressure generating unit45includes an FPC cable45C for connecting the piezoelectric elements45P to a driver circuit by a driver IC, for example.

As illustrated inFIG. 5B, for the piezoelectric element45P, a stacked piezoelectric element (PZT) in which a piezoelectric material45Pp and an internal electrode45Pe are alternately stacked can be used. The internal electrode45Pe includes a plurality of individual electrodes45Pei and a plurality of common electrodes45Pec. The internal electrode45Pe in the present embodiment alternately connects the individual electrode45Pei and the common electrode45Pec to an end face of the piezoelectric material45Pp. Further, the piezoelectric element45P in the present embodiment uses the d33 direction as the piezoelectric direction of the piezoelectric material45Pp. With this configuration, the pressure generating unit45can pressurize or depressurize the ink within the liquid chamber40F using a piezoelectric effect indicating the displacement in the d33 direction of the piezoelectric element45P. The pressure generating unit45may pressurize or depressurize the ink within the liquid chamber40F using displacement in the d31 direction of the piezoelectric element45P or arrange piezoelectric elements in a row for one discharge port40N. The supports may be formed simultaneously with the piezoelectric elements45P by dividing the piezoelectric elements45P. In other words, the discharge head40K can use piezoelectric element members as the supports by applying no voltage to the piezoelectric elements45P.

The following specifically describes a pulling ejection/pushing ejection operation when the discharge head40K discharges the ink from the discharge ports40N of the nozzles.

The discharge head40K in the present embodiment first decreases voltage being applied to the piezoelectric elements45P of the pressure generating unit45from a reference potential to shrink the piezoelectric elements45P in their stacking direction. The discharge head40K bends the vibration plate42by the shrinkage of the piezoelectric elements45P. In this process, the discharge head40K expands the volume of the liquid chamber40F by the bending of the vibration plate42. With this expansion, the discharge head40K can cause the ink to flow into the liquid chamber40F from the common liquid chamber40D.

Next, the discharge head increases the voltage being applied to the piezoelectric elements45P to elongate the piezoelectric elements45P in the stacking direction. The discharge head40K deforms the vibration plate42toward the discharge ports40N by the elongation of the piezoelectric elements45P. In this process, the discharge head40K reduces the volume of the liquid chamber40F by the deformation of the vibration plate42. With this volume reduction, the discharge head40K can apply pressure to the ink within the liquid chamber40F. The discharge head40K can discharge and eject the ink from the discharge ports40N of the nozzles by pressurizing the ink.

Subsequently, the discharge head40K restores the voltage being applied to the piezoelectric elements45P to the reference potential to restore the vibration plate42to the initial position. In this process, the discharge head40K reduces the pressure within the liquid chamber40F by the expansion of the liquid chamber40F to charge and replenish the ink within the liquid chamber40F from the common liquid chamber40D. Further, after the vibration of the meniscus face of the discharge ports40N of the nozzles attenuates and stabilizes, the discharge head40K shifts to operation for the next ink discharge and repeats the above-described operation.

A method for driving the discharge head40K that can be used in the present embodiment is not limited to the pulling ejection/pushing ejection operation. In other words, the method for driving the discharge head40K can perform pulling ejection, pushing ejection, and the like by controlling the driving waveform of the voltage to be applied to the piezoelectric elements45P.

From the foregoing, the image forming apparatus100according to the present embodiment can form black-and-white or full-color images in the entire area of the image forming area by one conveying operation of the rolled paper Md using the four discharge heads40K,40C,40M, and40Y of the image forming unit40.

To determine the presence or absence of the necessity of maintenance apart from during printing such as before printing, test patterns are created. As the test patterns, a test pattern for detecting discharge clogging of the discharge heads40K,40C,40M, and40Y of the respective colors of the image forming unit40and a test pattern for detecting discharge clogging of the head of the posttreatment unit50are created. For the detection of the discharge clogging of the posttreatment unit50, the image forming unit40preferably forms a monochrome solid image with any one color, for example.

The pressure generating unit45that can be used in the present embodiment is not limited to the piezoelectric elements45P. In other words, for the pressure generating unit45, what is called a thermal type one may be used that heats the ink within the liquid chamber40F using a heating resistor to generate air bubbles as disclosed in Japanese Unexamined Patent Application Publication No. S61-59911, for example. For the pressure generating unit45, what is called an electrostatic type one may be used that arranges a vibration plate and an electrode on the wall faces of the liquid chamber40F so as to face each other and deforms the vibration plate through an electrostatic force generated between the vibration plate and the electrode as disclosed in Japanese Unexamined Patent Application Publication No. H06-71882, for example.

The posttreatment unit50is a unit that treats the recording medium after the image has been formed. The posttreatment unit50in the present embodiment posttreats the surface of the rolled paper Md on which the image has been formed by the image forming unit40with a posttreatment liquid. This posttreatment is treatment to discharge the posttreatment liquid described below onto the rolled paper Md and to accumulate the posttreatment liquid. The posttreatment liquid is formed in a shape such as a spot-like shape or a banded shape. With this treatment, the image-formed rolled paper Md can be improved in rubfastness and glossiness, and in addition, can be improved also in storage stability such as waterproofness, lightfastness, and gas resistance.

FIGS. 6A and 6Bare illustrative diagrams illustrating an example of the rolled paper Md after image formation has been performed by the image forming apparatus100.FIG. 6Ais a top view of the image-formed rolled paper Md, andFIG. 6Bis a sectional view in a side longitudinal direction of the image-formed rolled paper Md.

Referring toFIG. 6A, this example illustrates how the pretreatment liquid20L has been applied to the surface of the rolled paper Md at the start of the posttreatment by the posttreatment unit50and an ink40Ink for image formation has been further discharged, for example. The posttreatment unit50performs treatment to discharge and accumulate transparent droplets50L as the posttreatment liquid onto the image-formed rolled paper Md as the posttreatment so as to be similar in the following. How the transparent droplets50L are accumulated on the ink40Ink is clear by referring toFIG. 6B. The transparent droplets50L are discharged onto an area at least smaller than that of the pretreatment liquid20L to be accumulated. In this sectional view, the ink40Ink is discharged onto the entire surface, whereas the transparent droplets50L are discharged onto an area smaller than the area of the ink40Ink to be accumulated.

AlthoughFIG. 6AandFIG. 6Billustrate the transparent droplets50L formed in a spot-like shape, the transparent droplets50L may be a banded shape in a direction orthogonal to the section instead thereof.

The transparent droplets50L may be discharged onto an area smaller than the image-formed surface area to be accumulated at least in the image-formed part of the rolled paper Md, and in a non-image-formed part, the transparent droplets50L may be discharged or are not necessarily discharged.

As a method of posttreatment, the posttreatment liquid is preferably discharged onto only a specific part of the image-formed area of the rolled paper Md to be accumulated. The posttreatment unit50further preferably changes a discharge amount as the application amount of the posttreatment liquid and a method of discharge as a method of application based on the type, the permeability, the glossiness, and the resolution of the recording medium such as the rolled paper Md and an application amount as the liquid amount of the pretreatment liquid applied by the pretreatment unit20.

The posttreatment unit50according to the present embodiment can discharge the posttreatment liquid with a desired discharge amount so as to be a desired spot-like shape or a desired banded shape at any area as any location using a discharge head similar to those of the image forming unit40illustrated inFIG. 4.

Specifically, the posttreatment unit50can select firstly discharging the post treatment liquid onto the entire area of an image-formable range, secondly discharging the post treatment liquid onto an image-formed area, thirdly discharging the post treatment liquid onto only an area of an image-formed part to be a dot discharge part, and the like to the rolled paper Md. The posttreatment unit50can select fourthly discharging the post treatment liquid onto the periphery of the image-formed area as a wider area than the image-formed area of the rolled paper Md by +1 dot, 2 dots or more, or the like. Further, the posttreatment unit50can discharge the posttreatment liquid onto an n % area so as to be a spot-like shape or a banded shape to a selected area onto which the posttreatment liquid is to be discharged. In some illustrative cases, the n % can be 5 to 50%. The n % can be a value preset by experiment, numerical calculation, or the like.

As a method for discharging the transparent droplets50L, the posttreatment unit50according to the present embodiment can select firstly discharging the transparent droplets50L based on print Duty, secondary discharging the transparent droplets50L based on the droplet amount of the transparent droplets50L to be discharged, and the like. In this process, the posttreatment unit50may calculate the print Duty and the droplet amount of the transparent droplets50L from input information such as print image data and determine the method for discharging the transparent droplets50L based on the calculated print Duty and the like.

Consequently, the image forming apparatus100according to the present embodiment can discharge and accumulate the posttreatment liquid only onto the specific part of the image-formed area using the posttreatment unit50compared with a case in which the posttreatment liquid is discharged and applied onto the entire surface of the recording medium such as the rolled paper Md. Consequently, the image forming apparatus100according to the present embodiment can reduce a time required for the posttreatment, especially a time required for drying the posttreatment liquid. In addition, the liquid amount of the posttreatment liquid required for the posttreatment can be reduced. Consequently, costs required for the posttreatment can be reduced.

The method of posttreatment by the posttreatment unit50is not limited to a particular method and may be selected as appropriate in accordance with the type of the posttreatment liquid. The method of posttreatment by the posttreatment unit50more preferably uses a method similar to the method for discharging inks by the image forming unit40in view of the downsizing of the apparatus and the storage stability of the posttreatment liquid. Consequently, similarly also in terms of configuration, as described with reference toFIG. 4A, the posttreatment liquid discharge unit includes a plurality of discharge ports50N of nozzles or print nozzles on a nozzle face. A discharge head50H as the posttreatment liquid discharge unit including the nozzle plate43is mounted on a carriage56described below with reference toFIG. 7. This discharge head50H is a second discharge unit discharging the transparent droplets50L as the posttreatment liquid.

When the posttreatment liquid is discharged, a water soluble organic solvent, which is a wetting agent used in the method for discharging inks by the image forming unit40, is preferably contained in an appropriate amount.

The posttreatment unit50according to the present embodiment preferably has a dry adhesion amount of the posttreatment liquid of 0.5 g/m2to 10 g/m2.

The posttreatment unit50according to the present embodiment can use a treatment liquid containing a component that can form a transparent protective layer on the rolled paper Md as the recording medium, as the posttreatment liquid. The treatment liquid containing the component that can form the transparent protective layer is a treatment liquid containing a water-dispersible resin containing a resin, a water-soluble organic solvent as a wetting agent, a penetrant, a surfactant, water, and other components as needed, for example. The posttreatment liquid may be a resin composition or a thermoplastic resin containing a component polymerized by UV irradiation. Further, the posttreatment liquid is preferably a thermoplastic resin emulsion in order to improve glossiness and fixability. Consequently, the posttreatment unit50can increase the glossiness of the surface of the image-formed rolled paper Md or protect the surface of the rolled paper Md with a resin layer in accordance with the method of discharge as the method of application.

Using the posttreatment unit50described above can prevent an ink image on the rolled paper Md from being stripped and separated caused by the surface of the image-formed rolled paper Md getting rubbed against another object such as another recording medium and improve rubfastness as rubbing resistance. Further, the occurrence of quality problems such as the blur, the density, the tone, the glossiness, and the set-off of the formed image and problems concerning waterproofness, weatherproofness, and other image robustness can be reduced.

The maintenance-and-restoration units90A and90B are maintenance units that perform the maintenance and restoration of the image forming unit40and the posttreatment unit50. When the discharge heads40K,40C,40M, and40Y of the first discharge unit and the discharge head50H of the second discharge unit described with reference toFIG. 4Aare used for a long time, they may be clogged with the inks and the posttreatment liquid. Given this situation, other than during printing such as before printing, a maintenance-and-restoration operation of cleaning and maintenance is preferably performed. The following discloses an example of the maintenance-and-restoration units90A and90B when line type liquid discharge heads are used for the image forming unit40and the posttreatment unit50.

FIG. 7is a diagram illustrating a schematic structure of the image forming unit40and the posttreatment liquid discharge unit of the image forming apparatus100and their maintenance-and-restoration units90A and90B. Referring toFIG. 7, the discharge heads40K,40C,40M, and40Y as the first discharge unit of the image forming unit40and the discharge head50H as the second discharge unit of the posttreatment unit50are configured to be movable up and down and are arranged facing the conveying belt81as the conveying unit. The conveying belt81conveys the rolled paper Md in the arrowed conveyance direction Xm. The maintenance-and-restoration unit90A is provided upstream in the conveyance direction Xm of the rolled paper Md on the right side inFIG. 7, whereas the maintenance-and-restoration unit90B is provided downstream in the conveyance direction of the rolled paper Md on the left side inFIG. 7.

The discharge heads40K,40C,40M, and40Y as the first discharge unit of the image forming unit40are installed in the carriage46, whereas the discharge head50H as the second discharge unit of the posttreatment liquid discharge unit is installed in the carriage56.

The carriages46and56move up and down and can thereby move between a position close to the conveying unit80illustrated inFIG. 7, that is, a recording position as a printing position that discharges the inks and the liquid of the posttreatment liquid and a separated position as a position separated from the conveying unit80indicated as the dotted-line part. This separated position is a maintenance position at which both the image forming unit40and the posttreatment unit50perform maintenance by the maintenance-and-restoration units90A and90B, is a waiting position waiting for a next operation, and a restoration position at which maintenance is performed.

To perform the up-and-down move, the carriages46and56are supported by carriage position moving units47and57, respectively, for example. By moving the carriage position moving units47and57, the positions of the carriages46and56move up and down relative to the casing74of the printer engine72E including the conveying belt81. AlthoughFIG. 7indicates the carriage position moving units47and57by arrows, a moving mechanism combining rails and rollers in structure may be used, or the carriages46and56may be lifted using arms or the like.

In the conveying unit80, the conveying belt81is stretched between a drive roller83rotated by a motor and a driven roller82to be circled, and the rolled paper Md is conveyed in the conveyance direction Xm by the circling of the conveying belt81supported by a support member84. In this process, the support member84may include a suction unit or an electrostatic attraction unit for attracting the rolled paper Md during conveyance.

The maintenance-and-restoration unit90A includes an engaging unit91A and a cleaning unit95A, whereas the maintenance-and-restoration unit90B similarly includes an engaging unit91B and a cleaning unit95B.

The engaging unit91A reciprocates relative to a facing area facing the discharge heads40K,40C,40M, and40Y of the image forming unit40at the separated position and is selectively engaged with the discharge heads40K,40C,40M, and40Y when maintenance is performed. The engaging unit91B reciprocates relative to a facing area facing the discharge head50H of the posttreatment liquid discharge unit at the separated position and is engaged with the discharge head50H when maintenance is performed.

The maintenance-and-restoration units90A and90B are similar in structure except the number of cap parts and the inks and the liquid of the posttreatment liquid to be received, and the following describes the maintenance-and-restoration unit90B of the posttreatment unit50to be controlled and omits a description of the maintenance-and-restoration unit90A. Consequently, the same components are denoted by the same reference numerals with the symbols attached to the ends of the numerals replaced.

The engaging unit91B includes a cap part92B, a wiper93B, and a fixing member94B that fixes the cap part92B and the wiper93B. The cap part92B is engaged with the discharge head50H that has occupied the separated position to seal and cap the discharge ports50N of the nozzles of the discharge head50H. During maintenance, the discharge head50H performs what is called idle discharge that discharges the posttreatment liquid with the cap part92B engaged, and the cap part92B functions as an idle discharge receptacle that receives the posttreatment liquid discharged from the discharge head50H by this idle discharge. The wiper93B wipes the posttreatment liquid that has flowed out of the discharge head50H at the separated position to wipe and clean the discharge head50H.

The cleaning unit95B cleans the cap part92B, the wiper93B, and the like with the engaging unit91B returned to a home position after the reciprocation of the engaging unit91B during maintenance. The cleaning of the engaging unit91B by the cleaning unit95B may be regularly performed in other situations such as after image formation with a certain number of sheets.

The maintenance-and-restoration unit90B includes a pump96B as a suction unit for suctioning the posttreatment liquid within the discharge head50H with the cap part92B engaged with the discharge head50H at the separated position and causing the posttreatment liquid to flow out of the discharge head50H. Further, the maintenance-and-restoration unit90B includes a discharge channel that couples the cap part92B and the pump96B to discharge the posttreatment liquid to the outside of the discharge head50H and a liquid storage that is connected to the discharge channel to store therein the ink and the liquid of the posttreatment liquid that have flowed out of the discharge head50H.

FIG. 8is an illustrative diagram illustrating a maintenance-and-restoration operation of the image forming unit40and the posttreatment liquid discharge unit by the maintenance-and-restoration units90A and90B. Referring toFIG. 8, this example illustrates how the maintenance-and-restoration operation has been performed using the maintenance-and-restoration units90A and90B having the configuration described above. In this case, the image forming unit40and the posttreatment unit50have moved upward to be at the separated positions, and the engaging units91A and91B of the maintenance-and-restoration units90A and90B have stopped immediately below the discharge heads40K,40C,40M, and40Y and the discharge head50H at the separated positions and have been engaged therewith.

FIG. 9is a plan view of the image forming unit40, the posttreatment liquid discharge unit, and the maintenance-and-restoration units90A and90B illustrated inFIG. 7. Referring toFIG. 9, the maintenance-and-restoration unit90A includes cap parts92K,92C,92M, and92Y corresponding to the discharge heads40K,40C,40M, and40Y, respectively, of the image forming unit40in a direction perpendicular to the conveyance direction Xm of the rolled paper Md. The maintenance-and-restoration unit90B includes the cap part92B.

The maintenance-and-restoration units90A and90B include moving units that move the engaging units91A and91B. The moving units include reciprocating units97,98,99K,99C,99M, and99Y and reciprocating units97,98, and99B that reciprocate the engaging units91A and91B relative to the discharge heads40K,40C,40M, and40Y and the discharge head50H. Also included are up-and-down moving units75A and75B that support the reciprocating units97,98,99K,99C,99M, and99Y and the reciprocating units97,98, and99B to drive the cap parts92A and92B up and down integrally with the engaging units91A and91B.

The reciprocating units97,98,99K,99C,99M, and99Y and the reciprocating units97,98, and99B include the following parts. Specifically, included are fixed members94A and94B that are integral with the engaging units91A and91B, respectively, an endless belt part of which fixes the fixed members94A and94B, and two pulleys around which the belt is wound. Also included are position sensors for detecting that the engaging units91A and91B are positioned immediately below the discharge heads40K,40C,40M, and40Y and the discharge head50H and detect that the engaging units91A and91B are positioned at the home position as a position as a starting point of the reciprocation. Further included are a support stage that supports the engaging units91A and91B from below in a freely reciprocating manner as described above and a motor as a drive unit that rotatingly drives the pulleys.

Also included is a base member on which a support part including belts as the up-and-down moving units75A and75B is mounted and that is arranged and fixed in the upper part with the moving space of the rolled paper Md interposed from the upper face of the casing74. This base member is connected to a shaft as a drive shaft the lower face part thereof is screwed and a plurality of gears that are fixed to the other end of the shaft and rotate integrally with the shaft, for example. The gears are connected to a stepping motor that rotatingly drives them.

Consequently, as the reciprocating units97,98,99K,99C,99M, and99Y and the reciprocating units97,98, and99B, the motor is driven to rotate the pulleys, whereby the belt can be circulated. With this circulation, the engaging units91A and91B can be reciprocated. In this process, the motor is driven so as to cause any of the position sensors to detect the fixed members94A and94B. Consequently, the cap parts92K,92C,92M, and92Y and the cap part92B can be accurately positioned at a position facing any of the discharge heads40K,40C,40M, and40Y or the discharge head50H at the separated positions or the home position.

With the cap parts92K,92C,92M, and92Y and the cap part92B positioned, the stepping motor is driven by a certain amount, that is, a certain number of pulses to move the base member upward. With this move, the engaging units91A and91B can be moved upward by a certain amount to be engaged with any of the discharge heads40K,40C,40M, and40Y or the discharge head50H that has occupied the separated position that the cap parts92K,92C,92M, and92Y and the cap part92B face. In place of the stepping motor, a combination of a sensor and a motor that detects the positions of the cap parts92K,92C,92M, and92Y and the cap part92B in the up-and-down direction may be used.

In the present embodiment, before maintenance and restoration is performed, a test pattern described below is formed, and a user, a manager, or a serviceman checks the test pattern printed on the rolled paper Md by visual inspection. Only when it is determined that maintenance (cleaning and the like) is required by the visual inspection, the following maintenance-and-restoration operation is performed. Further, in accordance with a result of the visual inspection of the test pattern, maintenance is performed only for a head that requires maintenance.

Specifically, in accordance with the result of the visual inspection of the test pattern, the maintenance-and-restoration operation is performed only for the cap parts92K,92C,92M, and92Y and the cap part92B that require maintenance. Further, the maintenance-and-restoration operation can be performed only for a part corresponding to the discharge port50N of a specific nozzle within the discharge head50H corresponding to the cap part92B corresponding to the posttreatment, for example, among these.

The maintenance-and-restoration operation is for the face of the discharge ports40N of the nozzles of the discharge heads40K,40C,40M, and40Y of the image forming unit40and the face of the discharge ports50N (not illustrated) of the nozzles of the discharge head50H of the posttreatment unit50. Capping is then performed by the cap parts92K,92C,92M, and92Y and the cap part92B for discharge. The inks and the posttreatment liquid within the discharge heads40K,40C,40M, and40Y and within the discharge head50H are then suctioned by a discharge pump through the cap parts92K,92C,92M, and92Y and the cap part92B. Suction sources are the discharge ports40N of the nozzles of the discharge heads40K,40C,40M, and40Y or the discharge ports50N of the nozzles of the discharge head50H.

After the completion of the suction from the discharge ports40N of the nozzles or the discharge ports50N of the nozzles as the maintenance-and-restoration operation, the engaging units91A and91B return to the home position. After that, the image forming unit40and the posttreatment unit50again move downward as before to return to the printing position on the conveying unit80, reaching a printable state.

In the present embodiment described with reference toFIG. 7toFIG. 9, the discharge heads40K,40C,40M, and40Y of the image forming unit40and the discharge head50H of the posttreatment unit50are mounted on the carriage46and the carriage56that are independent from each other. With this configuration, the image forming unit40and the posttreatment unit50can be maintained at different times.

However, the image forming unit40and the posttreatment unit50may be integrated to be mounted on the same carriage. In such a configuration, the maintenance-and-restoration units90A and90B are also integrated, and the moving mechanism to a maintenance-and-restoration unit90is simplified, and the cap parts92K,92C,92M, and92Y and the cap part92B are also simplified. In this case, an integrated engaging unit91collectively caps the discharge heads40K,40C,40M, and40Y and the discharge head50H to perform maintenance and restoration. Consequently, the integrated maintenance-and-restoration units90A and90B can be collectively arranged upstream or downstream in the conveyance direction Xm of the rolled paper Md in the image forming unit40or the posttreatment unit50.

The carry-out unit60is a unit that carries out the image-formed rolled paper Md. As illustrated inFIG. 1, this carry-out unit60in the present embodiment includes a storage unit61and a plurality of conveying rollers62. The carry-out unit60winds the image-formed rolled paper Md around a storage roll of the storage unit61using the conveying rollers62and the like to store therein the image-formed rolled paper Md.

When the rolled paper Md is wound around the storage roll of the storage unit61, if pressure acting on the rolled paper Md is large, a drying unit that further dries the rolled paper Md immediately before the winding may be provided in order to prevent another image from being transferred to the back face of the rolled paper Md.

FIGS. 10A and 10Bare schematic configuration diagrams illustrating an example of the controller70to be used in the image forming apparatus100.FIG. 10Ais a schematic diagram of an overall system configuration of the controller70, andFIG. 10Bis a functional block diagram of a detailed configuration of a host apparatus71included in the system configuration inFIG. 10A. The controller70illustrated inFIG. 10Acontrols the operation of the image forming apparatus100and gives instructions on operations to the components of the image forming apparatus100in the present embodiment.

The controller70according to the present embodiment may use production printing as a printing system. The production printing is a printable manufacturing system that performs image formation or printing on a large number of image formation media or print objects in a short time by efficiently performing job management, print data management, and the like. Specifically, the controller70according to the present embodiment performs raster image processor (RIP) processing that controls the printing operation of bitmap data and the like and printing processing based on the bitmap data and the like controlled by the RIP processing by separate apparatuses.

The controller70constructs a system of workflow that performs management from the creation of print data to the distribution of printed objects. In other words, the controller70according to the present embodiment separates an apparatus that performs the RIP processing that requires a processing time and an apparatus that performs the printing processing, thereby enabling high-speed printing.

Specifically, as illustrated inFIG. 10A, the controller70includes the host apparatus (a digital front end (DFE))71that perform the RIP processing and the like and a printer apparatus72that perform the printing processing and the like for the image forming apparatus100. The host apparatus71and the printer apparatus72are connected to each other via a plurality of data lines70LD and a control line70LC.

The following specifically describes the host apparatus71and the printer apparatus72included in the controller70.

The host apparatus71of the controller70illustrated inFIG. 10Ais an apparatus that performs the RIP processing based on print job data containing job data and print data output from a host apparatus. In other words, the host apparatus71according to the present embodiment creates pieces of print image data as pieces of bitmap image data corresponding to respective colors based on the print job data. The print image data in the present embodiment further contains data on the discharge of the posttreatment liquid discharged by the posttreatment unit50, that is, image data on the posttreatment.

The host apparatus71according to the present embodiment creates control information data for controlling the printing operation based on the print job data, information from the host apparatus, and the like. This control information data contains data on print form, print type, paper feed/ejection information, print face order, and print sheet size as print conditions, the data size, the resolution, the paper type information, the gray scale, and the color information of the print image data, information on the number of pages to be printed, and the like. The control information data in the present embodiment further contains data on the discharge of the posttreatment liquid discharged by the posttreatment unit50, that is, control data on the posttreatment.

The user, the manager, the serviceman, or the like inputs the information detected by the visual inspection during maintenance and restoration to the host apparatus71.

As illustrated inFIG. 10B, the host apparatus71in the present embodiment includes a central processing unit (CPU)71a, a read only memory (ROM)71b, a random access memory (RAM)71c, and a hard disk drive (HDD)71d. The host apparatus71also includes an external I/F71e, an I/F71ffor control information, and an I/F71gfor image data. The I/F is an expression indicating an interface. The host apparatus71further includes a bus71hthat connects the CPU71aand the like. In other words, the host apparatus71has a configuration that enables the CPU71aand the like to perform mutual transmission and reception via the bus71h.

The CPU71acontrols the operation of the entire host apparatus71. The CPU71acontrols the operation of the host apparatus71using a control program and the like stored in the ROM71band the HDD71d.

The ROM71b, the RAM71c, and the HDD71dall store therein data and the like. The ROM71band the HDD71dstore therein a control program for controlling the CPU71ain advance. The RAM71cis used as a work memory of the CPU71a.

The external I/F71econtrols communication concerning transmission and reception with a host apparatus and the like outside the image forming apparatus100. The I/F71ffor control information controls the communication of the control information data. The I/F71gfor image data controls the communication of the print image data. The I/F71gfor image data in the present embodiment has a plurality of channels described below corresponding to the respective colors of the print image data.

The host apparatus71of the controller70according to the present embodiment receives the print job data transmitted from the host apparatus by the external I/F71eand stores the print job data in the HDD71dusing the CPU71a. The host apparatus71reads the print job data from the HDD71dusing the CPU71a. Further, the host apparatus71generates pieces of bitmap data of the respective colors, or yellow Y, cyan C, magenta M, and black K, based on the print job data read using the CPU71aand stores the generated pieces of bitmap data of the respective colors in the RAM71c. In this process, the CPU71aof the host apparatus71can generate the pieces of bitmap data of the respective colors by rendering page description language (PDL), for example, as the RIP processing and write out the pieces of bitmap data of the respective colors to the RAM71c.

Next, the host apparatus71compresses and encodes the pieces of bitmap data of the respective colors written out to the RAM71cand once stores the pieces of encoded bitmap data of the respective colors in the HDD71d.

Subsequently, when a printing operation is started by the printer apparatus72, the CPU71aof the host apparatus71reads the pieces of encoded bitmap data of the respective colors from the HDD71d, decodes the pieces of bitmap data of the respective colors, and writes the pieces of bitmap data of the respective colors in the RAM71c. Next, the host apparatus71reads the pieces of bitmap data of the respective colors from the RAM71cand outputs the pieces of bitmap data of the respective colors to the printer engine72E described below of the printer apparatus72via the respective channels of the I/F71gfor image data as the pieces of print image data of the respective colors. In this process, the host apparatus71can output the pieces of print image data to the printer apparatus72via the data lines TOLD illustrated inFIG. 10Aas the respective channels of the I/F71gfor image data. These data lines70LD correspond to data lines70LD-Y,70LD-C,70LD-M, and70LD-K for the respective colors inFIG. 11described below.

The host apparatus71according to the present embodiment transmits and receives the control information data to and from a printer controller72C of the printer apparatus72using the CPU71avia the I/F71ffor control information related to the control line70LC in accordance with the progress of the printing operation and the like.

Further, when the posttreatment is started by the posttreatment unit50, the host apparatus71according to the present embodiment reads encoded image data on the posttreatment from the HDD71dusing the CPU71aand outputs the encoded image data on the posttreatment to the printer engine72E via the data line70LD similarly to the bitmap data. This data line70LD corresponds to a data line70LD-P inFIG. 11described below.

The printer apparatus72of the controller70is an apparatus that controls operation for performing image formation on the rolled paper Md as the recording medium based on the print image data and the control information data input from the host apparatus71. The printer apparatus72in the present embodiment includes the printer controller72C and the printer engine72E illustrated inFIG. 1. As illustrated inFIG. 1, the printer engine72E includes the casing73for conveyance, the casing74of the inkjet printer main body, the image forming unit40, the posttreatment unit50, the maintenance-and-restoration units90A and90B, and the drying unit30including the drying unit32for posttreatment.

The printer controller72C controls the operation of the printer engine72E and transmits and receives the control information data and the like to and from the host apparatus71via the control line70LC. The printer controller72C transmits and receives the control information data and the like to and from the printer engine72E via the control line72LC. With this operation, the printer controller72C can write print information such as the various kinds of print conditions contained in the control information data and data on a test pattern for discharge in a resistor or the like of a printing controller to store therein the print condition. The printer controller72C can control the printer engine72E based on the control information data and perform printing corresponding to the print job data contained in the control information data.

FIG. 11is a functional block diagram illustrating an example of a basic configuration of the details of the controller70. Referring toFIG. 11, the printer controller72C of the printer apparatus72in the present embodiment includes a CPU72Cp and a printing controller72Cc. The printer controller72C connects the CPU72Cp and the printing controller72Cc in such a manner that they can perform mutual transmission and reception via a bus72Cb. The bus72Cb is connected to the control line70LC via a communication I/F.

The CPU72Cp controls the operation of the entire printer apparatus72using a control program stored in a ROM. The printing controller72Cc transmits and receives commands and status information to and from the printer engine72E based on the control information data transmitted from the host apparatus71. With this operation, the printing controller72Cc can control the operation of the printer engine72E.

The printer engine72E is an apparatus that controls operation to perform image formation on the rolled paper Md based on the print image data input from the host apparatus71and the control information data input from the printer controller72C. The printer engine72E is an apparatus that controls operation to perform the posttreatment based on the print image data containing the image data on the posttreatment input from the host apparatus71and the control information data on the image data on the posttreatment input from the printer controller72C.

As illustrated inFIG. 11, to the printer engine72E, the data lines70LD-Y,70LD-C,70LD-M, and70LD-K for the respective colors and the data line70LD-P as the data lines70LD are connected. The printer engine72E receives the print image data from the host apparatus71via the data lines70LD. With this operation, the printer engine72E can perform printing operations for the respective colors and the posttreatment with the posttreatment liquid based on the received print image data.

The printer engine72E in the present embodiment includes a plurality of data managing units72EC,72EM,72EY, and72EK for the respective colors and a data managing unit72EP. The printer engine72E also includes an image output unit72Ei to which the print image data and the like are input from the data managing unit72EC and the like and a conveyance controller72Ec that controls the conveyance of the rolled paper Md. The printer engine72E in the present embodiment further includes a posttreatment liquid output unit72Ep to which the image data on the posttreatment is input from the data managing unit72EP and a post-posttreatment drying controller72Epb that controls the operation of the drying unit30. In addition, the printer engine72E includes a maintenance-and-restoration controller72Er that controls the operation of a maintenance-and-restoration mechanism including the maintenance-and-restoration units90A and90B and the carriage position moving units47and57described with reference toFIG. 7.

The present embodiment includes a test pattern used in the maintenance-and-restoration operation described below other than during the normal printing as the image data. The printer engine72E may further include a pretreatment liquid application controller, a post-pretreatment drying controller, and a pre-winding drying controller.

FIG. 12is a functional block diagram illustrating an example of a detailed configuration of the data managing unit72EC of the controller70. The configurations of the other data managing units72EM,72EY,72EK, and72EP are similar to the configuration of the data managing unit72EC, and descriptions thereof are omitted.

Referring toFIG. 12, the data managing unit72EC includes a logic circuit72EC1and a memory unit72ECm. The logic circuit72EC1of the managing unit72EC is connected to the host apparatus71via the data line70LD-C. The logic circuit72EC1of the managing unit72EC is connected to the printing controller72Cc of the printer controller72C via the control line72LC.

The logic circuit72EC1in the present embodiment stores the print image data output from the host apparatus71in the memory unit72ECm based on a control signal output from the printing controller72Cc of the printer controller72C. The logic circuit72EC1reads print image data Ic corresponding to cyan C from the memory unit72ECm based on the control signal output from the printing controller72Cc of the printer controller72C and outputs the print image data Ic to the image output unit72Ei. Concerning the posttreatment, in the case of the data managing unit72EP of a logic circuit72ECp, image data Ip on the posttreatment and data for controlling the discharge position of a test pattern for discharge inspection are output to the posttreatment liquid output unit72Ep.

The memory unit72ECm can be a capacity that can store therein the print image data at least for three pages. The print image data for three pages indicates the print image data corresponding to a page being received transferred from the host apparatus71, the print image data corresponding to a page being output to the image output unit72Ei, and the print image data corresponding to the next page, for example.

For the data managing unit72EC, a hardware logic circuit including a combination of logic circuits and the like may be used. With this configuration, the data managing unit72EC can achieve higher-speed processing. The data managing unit72EC may perform logical determination for a control signal by a bit sequence, for example, using the logic circuit72EC1to determine processing to be performed.

FIG. 13is a functional block diagram illustrating an example of a detailed configuration of the image output unit72Ei of the controller70. The configuration of the posttreatment liquid output unit72Ep is basically similar to the configuration of the image output unit72Ei, and a description thereof is omitted. Referring toFIG. 13, the image output unit72Ei includes an output controller72Eic. The output controller72Eic outputs the pieces of print image data corresponding to the respective colors to the discharge heads40C,40M,40Y, and40K corresponding to the respective colors. With this operation, the output controller72Eic can control the operation of the discharge head40C and the like based on the pieces of print image data.

Specifically, the output controller72Eic individually controls the discharge head40C and the like. The output controller72Eic may simultaneously control the discharge head40C and the like using the input print image data Ic, for example. Further, the output controller72Eic may control the discharge head40C and the like based on a control signal input from a controller. The output controller72Eic may control the discharge head40C and the like based on operational input by the user, for example.

As described above, as part of the operation of position moving restoration, by the position moving units, at a time other than during printing, for the purpose of maintenance and restoration, position information is input and controlled so as to cause the image forming unit40and the posttreatment unit50to move up and down.

From the foregoing, the printer apparatus72according to the present embodiment inputs the print image data output from the host apparatus71to the discharge head40C and the like using the data managing unit72EC and the like and the output controller72Eic. In this process, the printer apparatus72can control the pieces of print image data of the respective colors independently from each other. The printer apparatus72can easily change the configuration of the printer engine72E in accordance with the number of colors of the print image data or the number of the discharge heads40K,40C,40M, and40Y. In other words, among the data managing unit72EC and the like and the discharge head40C and the like, only necessary ones are mounted, thereby producing a favorable effect about the downsizing of the apparatus and cost reduction.

When full-color printing with the four colors is performed, for example, the printer apparatus72according to the present embodiment can be provided with all of the data managing unit72EC and the like in the printer engine72E. With this configuration, the printer apparatus72can connect the respective pieces of output of the data managing unit72EC and the like to the discharge head40C and the like using the output controller72Eic.

When printing with one color of black K is performed, for example, the printer apparatus72can be provided with only one data managing unit72EK and one discharge head40K considering apparatus cost priority. With this configuration, the printer apparatus72can connect the output of the data managing unit72EK to the discharge head40K using the output controller72Eic.

Alternatively, when printing with one color of black K is performed, for example, one data managing unit72EK and four discharge heads40K may be provided considering printing speed priority. With this configuration, the image forming apparatus100can connect the output of the data managing unit72EK to the four discharge heads40K using the output controller72Eic. In this case, the image forming apparatus100can print the same color, or black K, a plurality of times in a superimposed manner and can achieve image formation with four times higher-speed printing than a case of image formation by one discharge head40K, for example. The following specifically describes some examples about inspection when discharging the droplets of the ink40Ink by the image forming unit40and discharging the droplets of the posttreatment liquid by the posttreatment unit50onto the rolled paper Md being conveyed in the image forming apparatus100.

FIG. 14is a diagram of an example of a test pattern P1for discharge inspection image-formed on the rolled paper Md as the discharged object by the image forming apparatus100according to Example 1 of the present invention. In Example 1, the ink40Ink and the posttreatment liquid are applied to the rolled paper Md by droplet flying by the discharge heads40K,40C,40M, and40Y and the discharge head50H that discharge droplets. Before starting printing that performs image formation on the rolled paper Md by this method by droplet flying, abnormal discharge such as the non-discharge or bending of the droplets of the ink40Ink discharged by the discharge heads40K,40C,40M, and40Y of the respective colors and the posttreatment liquid discharged by the discharge head50H is checked. For this purpose, the test pattern P1for discharge inspection as illustrated inFIG. 14is printed on the rolled paper Md. This test pattern P1is image-formed and inspected by discharging the colored droplets of the ink40Ink from the discharge ports40N of the nozzles of the discharge heads40K,40C,40M, and40Y and the transparent droplets50L of the posttreatment liquid from the discharge ports50N of the nozzles of the discharge head50H onto the rolled paper Md.

However, in the case of the posttreatment liquid as the transparent droplets50L, when the test pattern P1for discharge inspection is image-formed and printed on the rolled paper Md by the same method, the posttreatment liquid is transparent, and inspection thereon is difficult. This is because the user, the manager, or the serviceman sees reflected light using white light such as natural light to determine recognition details. Specifically, light with respective wavelengths is reflected by the transparent droplets50L printed on the rolled paper Md, and it is difficult to visually distinguish the reflected light of the rolled paper Md and the reflected light of the transparent droplets50L from each other. For information, as to light transmittance, the droplets of the transparent posttreatment liquid are higher than the droplets of the four-color ink40Ink of the respective colors, or black K, cyan C, magenta M, and yellow Y. Consequently, the transparent droplets50L of the posttreatment liquid can be regarded as an ink with high light transmittance.

Principle

FIG. 15is a diagram illustrating the detection principle of discharge inspection by an inspection apparatus to be used in the image forming apparatus100according to Example 1 of the present invention. Referring toFIG. 15, the inspection apparatus according to Example 1 includes the discharge head50H of the posttreatment unit50as a liquid discharge head that discharges the transparent droplet50L of the posttreatment liquid onto the rolled paper Md as the discharged object. Also included is a first light source Lp that irradiates the pattern formed by the transparent droplet50L discharged onto the rolled paper Md with light having a single peak wavelength to cause a difference between brightness and darkness. This example schematically illustrates relation between the transparent droplet50L image-formed and printed on the rolled paper Md and an optical path and illustrates how the test pattern P1for discharge inspection has been printed on the rolled paper Md and is being visually inspected. Although this example schematically illustrates how the inspection is visually performed, the test pattern P1can also be detected by a sensor such as a scanner as described below.

When discharge inspection on the transparent droplet50L or a light-colored ink is performed, when a light source having a single peak wavelength is used for the first light source Lp, a difference between brightness and darkness occurs. This difference between brightness and darkness is caused by light obtained by narrow-band reflected light that has been reflected simply by the surface of the rolled paper Md other than the transparent droplet50L and light obtained by the narrow-band reflected light that has passed through the transparent droplet50L while being reflected and has been reflected by the surface of the rolled paper Md. With this difference between brightness and darkness, the surface of the rolled paper Md and the transparent droplet50L can be easily distinguished from each other, and discharge detection can be performed by visual inspection or by a sensor such as a scanner as detection principle.

For the light having a single peak wavelength, a red light source (a red light-emitting diode (LED)) with a peak wavelength of 660 nm or a yellow light source (a yellow LED) with a peak wavelength of 590 nm can be used, for example. Such cases also produce a higher effect than a case using white light. Only a single peak wavelength is required, and a laser light source as a single wavelength light source can also be used. Further, the light source that emits light having a single peak wavelength is preferably a light source having a characteristic of a half-value width of 70 nm or less in relative radiation intensity.

Light with a shorter wavelength has a higher refractive index in general, and light reflected within the transparent droplet50L having a shorter wavelength is easily detected. Specifically, light having a peak wavelength of 570 nm or less is favorable when used for the discharge detection of the transparent droplet50L. A green light source (a green LED) or a blue light source (a blue LED) may be used, for example. The short wavelength referred to in Example 1 is light having a peak wavelength of 570 nm or less. Examples of the short-wavelength, blue, inexpensive blue light source having a single peak wavelength includes the blue LED. The blue LED is inexpensive and has a shorter wavelength and is favorable when used for the discharge detection of a transparent ink. Consequently, the peak wavelength is preferably in the range of 380 nm to 500 nm.

Thus, the inspection apparatus in Example 1 prints the test pattern P1for discharge inspection on the rolled paper Md when detecting faulty discharge from the discharge ports50N of the nozzles of the discharge head50H that discharge the transparent droplets50L. Subsequently, for this test pattern P1for discharge inspection, non-discharge or faulty discharge is detected using the light source having a single peak wavelength.

Example of Scanner

To automatically perform discharge detection inspection on the transparent droplets50L, for the rolled paper Md on which the transparent droplets50L have been formed, an image on the rolled paper Md may be read by the scanner101provided on the downstream side of the drying unit30illustrated inFIG. 1. The state of discharge detection is determined from the image read by the scanner101. According to this method, the light source of the scanner101is the first light source Lp, and the image is read using the light source having a single peak wavelength. In accordance with this procedure, the image is clear, and the determination of the discharge detection inspection is easy. The scanner101includes a function as a line-shaped light-receiving sensor Lr that receives light that has been emitted by the line-shaped first light source Lp and has been reflected by the transparent droplets50L and the rolled paper Md.

For the light source of the scanner101itself, there is less need to consider the health of human eyes, and a laser light source can also be used. A UV-LED as a light source having a peak wavelength in the range of 265 nm or more and less than 380 nm known as a shorter-wavelength LED can also be used. However, an LED having a peak wavelength in the range of 265 nm to 340 nm may damage the discharged object such as the rolled paper Md and may be used only when the discharged object is not damaged. Further, when the UV-LED is used, a sensor having sensitivity properties in the range is required to be used as the scanner101. Sensors having high spectral sensitivity properties in the UV range are known and are not described in detail in this example. Whatever the case may be, when the scanner101is used, the first light source Lp having a single peak wavelength in the range of 265 nm to 1,000 nm can be used. The wavelength 1,000 nm is the upper limit of the detection range of the scanner101.

FIG. 17is a flowchart of the operational principle of discharge detection by the scanner101provided in an inspection apparatus for a discharge detection pattern according to Example 1. Referring toFIG. 17, in the discharge detection by the scanner101, first, areas in which the respective colors have been discharged are scanned to acquire image information, and determination whether there is any difference between brightness and darkness in the image information (Step S1) is performed. This presence or absence of the difference between brightness and darkness appears based on a difference between brightness and darkness in the state of reflected light and is determined based on whether the gray scale values of pixels in the image information reach a certain threshold. As a result of this determination, if there is any difference between brightness and darkness, the discharge detection is regarded as being favorable (Step S2), and the process shifts to actual printing. In contrast, if there is no difference between brightness and darkness, the discharge detection is regarded as being non-discharge or faulty discharge (Step S3), and maintenance by the maintenance-and-restoration units90A and90B is performed.

Example of Visual Inspection

FIG. 19is a schematic diagram illustrating an example of a basic configuration of an inspection apparatus for visual inspection for the discharge detection pattern according to Example 1. When the discharge detection inspection on the transparent droplet50L is performed by visual inspection, an inspection stage102as a base separate from the image forming apparatus100is used as illustrated inFIG. 19. The first light source Lp may be held on one end of the inspection stage102by an illumination mounting tool103including an illumination operating unit104. This first light source Lp forms the inspection apparatus together with the discharge head50H. A platform truck is mounted on the bottom face of the inspection stage102to make the inspection stage102travelable. The illumination mounting tool103with a link structure is mounted on the inspection stage102with another tool such as a clamp, and the first light source Lp is mounted on the tip side of the illumination mounting tool103. The inspection stage102may be foldable type. An operating knob may be used for the illumination operating unit104. Known techniques can be used for these mounting structures.

For information, although the inspection apparatus that performs the discharge detection inspection by visual inspection has been described as a separate body from the image forming apparatus100, the inspection stage102may be installed at the rear of the image forming apparatus100so as to be lowered by one step. Whatever the case may be, as to how the rolled paper Md is brought to the inspection stage102, if the rolled paper Md is wound around the storage unit61of the carry-out unit60as illustrated inFIG. 1, an inspector will cut out the rolled paper Md and mount the rolled paper Md on the inspection stage102. Apart from this, if the image forming apparatus100includes a cutter, the rolled paper Md will be cut using it and will be mounted on the inspection stage102. A structure in which the carry-out unit60includes a cutter in place of the winding function to the storage unit61is also known, and such a structure may be employed.

When the discharge detection inspection is performed on the transparent droplet50L by visual inspection, a laser light source and a short-wavelength LED, which may damage human eyes, are not preferably used. Given these circumstances, in the case of visual inspection, a light source having a peak wavelength in the visible range from 375 nm to 780 nm and having certain degree of bandwidth may be used, and an LED light source or an organic EL light source having high color purity can be used, for example. In particular, a violet LED, a blue LED, and a green LED having a peak wavelength in the range of 380 nm to 570 nm are preferable because of easiness of visual inspection. It can be said that the blue LED is optimum, because it generally has a peak wavelength in the range of 450 nm to 500 nm and is available at a low price.

Example of Performing Detection Together with Colored Ink

When the discharge detection inspection on the transparent droplet50L is performed, when the discharge detection patterns of the colored ink40Ink are simultaneously printed to perform the discharge detection inspection for each color of the colored ink40Ink, a time required for the ink discharge detection inspection on all of the heads is reduced, and a time until actual printing is performed is reduced. The colored ink40Ink indicates having colors that can be easily visually inspected or detected under a white light source. Specifically, the colored ink40Ink indicates inks of process colors such as black K, cyan C, magenta M, and yellow Y and special inks such as pink and orange.

FIG. 16is a diagram of discharge detection patterns when discharge detection inspection is performed together with colored inks by the inspection apparatus according to Example 1. This example illustrates how discharge detection patterns PK, PC, PM, PY, and Pt have been image-formed and printed for each color in the discharge heads40K,40C,40M, and40Y for the respective colors to be used and the discharge head50H for the posttreatment liquid on the rolled paper Md. The colored ink40Ink can be visually inspected or detected under a white light source, and the white light source may be provide separately, and the discharge detection inspection may be performed under the white light source. When the discharge detection inspection on the transparent droplet50L is performed, the white light source is switched to a light source having a single peak wavelength, whereby the discharge detection inspection can be appropriately performed on the colored ink40Ink and the transparent droplet50L.

When non-discharge is detected from these printed discharge detection patterns PK, PC, PM, PY, and Pt, when light of a color that is low in the spectral reflectance properties of the colored ink40Ink that has formed the discharge detection patterns PK, PC, PM, PY, and Pt is emitted, visual inspection or detection is performed more easily. Given this situation, a second light source Lp′ that emits light of the color corresponding to a region that is low in the spectral reflectance properties of this colored ink40Ink is preferably provided.

The Ink40Ink of magenta M is easily detected when a green LED having a peak wavelength of 500 nm to 570 nm is emitted, for example. Similarly, the ink40Ink of cyan C is easily detected when a red LED having a peak wavelength of 600 nm to 700 nm is emitted. The ink40Ink of yellow Y is easily detected when a green light source having a peak wavelength of 450 nm to 500 nm is emitted. For the discharge detection inspection on the transparent droplet50L, a blue LED can be used, for example. The color that is low in the spectral reflectance properties of the colored ink40Ink can also be referred to as a complementary color, and the light of the respective colors can also be referred to as a complementary color light source.

FIG. 18is a schematic diagram illustrating a basic configuration according to another example of an inspection apparatus for automatic operation for the discharge detection pattern according to Example 1. A scanner101′ in this example also includes the line-shaped second light source Lp′ that emits light of the color in the area having low spectral reflectance properties of the colored ink40Ink in addition to the line-shaped first light source Lp. The functions as the line-shaped light-receiving sensor Lr also receives light that has been emitted by the second light source Lp′ and has been reflected by the transparent droplet50L or the rolled paper Md in addition to the first light source Lp. The second light source Lp′ may be a plurality of light sources and may be a light source that can switch among a plurality of colors. The first light source Lp, the second light source Lp′, and the light-receiving sensor Lr are all arranged in a line shape and scan the rolled paper Md in the conveyance direction Xm while maintaining a certain spacing. To automatically perform the discharge detection inspection on the colored ink40Ink and the transparent droplet50L, as to the discharge detection patterns PK, PC, PM, PY, and Pt of the respective colors, the images on the rolled paper Md may be read by the scanner101′ illustrated inFIG. 18. With the first light source Lp and the second light source Lp′ as the light sources of the scanner101′, the images of the discharge detection patterns PK, PC, PM, PY, and Pt of the respective colors are read while switching between the blue light source for the transparent droplet50L and the light source of the color that is low in the spectral reflectance properties for the colored ink40Ink as described above. For information, as another example of the inspection apparatus for visual inspection, as illustrated inFIG. 20, the second light source Lp′ may be separately mounted on the inspection stage102by a mounting structure similar to the one described with reference toFIG. 19. In this inspection apparatus, the second light source Lp′ is held by the illumination mounting tool103including the illumination operating unit104on the side facing the first light source Lp.

The spectral reflectance properties of the ink of yellow Y is as low as 450 nm to 500 nm, and when the discharge detection pattern Pt of the transparent droplet50L is printed before or after the discharge detection pattern of the ink of yellow Y as illustrated inFIG. 16to perform the discharge detection inspection, all that is required is to emit the same blue LED when the discharge detection inspection is performed. Such being the case, the first light source Lp and the second light source Lp′ of light source emission are not required to be switched between the ink of yellow Y and the transparent droplet50L. In addition, the images can be read simultaneously, and an inspection time is reduced.

FIG. 21is a diagram of an example of a test pattern P2for discharge inspection image-formed on the rolled paper Md by an image forming apparatus according to Example 2 of the present invention. Also in Example 2, the ink40Ink and the posttreatment liquid are applied to the rolled paper Md by droplet flying by the discharge heads40K,40C,40M, and40Y and the discharge head50H that discharge droplets. Before starting printing that performs image formation on the rolled paper Md by this method by droplet flying, abnormal discharge such as non-discharge or bending of the droplets of the ink40Ink discharged by the discharge heads40K,40C,40M, and40Y of the respective colors and the posttreatment liquid discharged by the discharge head50H is checked. For this purpose, the test pattern P2for discharge inspection as illustrated inFIG. 18is printed on the rolled paper Md.

This test pattern P2for discharge inspection has been image-formed and printed by setting the nozzle rows of the discharge heads40K,40C,40M, and40Y and the discharge head50H. The discharge head50H includes a first nozzle row that discharges the transparent droplets50L while moving in a first direction relative to the rolled paper Md. The discharge heads40K,40C,40M, and40Y include a second nozzle row in which the discharge ports40N of a plurality of nozzles are arranged in a second direction orthogonal to the first direction. The test pattern P2for discharge inspection is formed to have m (m is a natural number of 2 or more) pattern rows arranged in the first direction, the patterns in each of the m pattern rows being arranged with an interval of (m−1). InFIG. 21, the number of pattern rows m is 8, and in each of the pattern rows, the patterns are arranged with an interval of 7, for example.

This test pattern P2for discharge inspection has been image-formed and printed by discharging the ink40Ink as the colored droplets from the discharge ports40N of the nozzles of the discharge heads40K,40C,40M, and40Y onto the rolled paper Md. However, in the case of the transparent droplets50L, when the test pattern P2for discharge inspection is printed on the rolled paper Md from the discharge ports50N of the nozzles of the discharge head50H by the same method, being transparent makes the inspection difficult. This fact is as described in Example 1.

When the discharge inspection is performed by printing the test pattern P2for discharge inspection on the rolled paper Md, treatment similar to that of Example 1 described with reference toFIG. 15is performed. Also in Example 2, similarly to Example 1, when faulty discharge from the discharge ports50N of the respective nozzles of the discharge head50H of the transparent droplets50L is detected, the transparent droplets50L are discharged from the discharge head50H onto the rolled paper Md to print the test pattern P2. Subsequently, the transparent droplet50L of the test pattern P2is irradiated with light having a single peak wavelength by the first light source Lp, and non-discharge or faulty discharge of each of the nozzles of the discharge head50H is detected from the state of brightness and darkness of its reflected light. Using a light source that emits light having a single peak wavelength to cause a difference between brightness and darkness as the first light source Lp and the use of the blue LED being preferable are also similar to Example 1.

Also in Example 2, when the discharge detection of the transparent droplet50L is performed, printing the test pattern P2for the discharge inspection of the colored ink40Ink simultaneously and performing the discharge detection for each ink color are also similar to Example 1 described with reference toFIG. 16. The configuration of the inspection apparatus when performing the discharge inspection on the colored ink40Ink and the transparent droplet50L automatically or by visual inspection or the procedure when the discharge inspection is performed by switching the light source for the respective colors including the case of using the second light source Lp′ are also similar to Example 1, producing a similar effect. In Example 2, the test pattern P2is as illustrated inFIG. 21, which is suitable for detection by visual inspection.

The technical essence of the inspection apparatus described in the examples can be described as a method of inspection. This method of inspection includes a liquid discharge step that discharges a transparent liquid onto a discharged object from a liquid discharge head and a light irradiation step that irradiates a pattern formed by the transparent liquid discharged onto the discharged object at the liquid discharge step with light having a single peak wavelength from a first light source to cause a difference between brightness and darkness. The light having a single peak wavelength can be selected from being light having a peak wavelength in the wavelength range of 265 nm to 1,000 nm and being light having a peak wavelength in the wavelength range of 375 nm to 780 nm. The light having a single peak wavelength can also be selected from being light having a peak wavelength in the wavelength range of 380 nm to 570 nm and being light having a peak wavelength in the wavelength range of 450 nm to 500 nm. Whatever the case may be, an inspection step is preferably included that inspects the non-discharge or faulty discharge of the liquid discharge head based on the state of reflection light reflected by the transparent liquid and parts other than that. The state of the reflected light preferably appears as a difference between brightness and darkness.

According to these examples, when the faulty discharge of the transparent droplet50L is detected, the test patterns P1and P2are irradiated with the light having a single peak wavelength by the first light source Lp to cause a difference between brightness and darkness. Consequently, the faulty discharge of the transparent droplet50L can be appropriately detected from the relation of brightness and darkness without using the colored ink40Ink. In addition, there is no influence of the non-discharge or bent discharge of the colored ink40Ink, and the accuracy of detecting the non-discharge of the transparent droplet50L increases. Further, maintenance for making the non-discharge or bent discharge of the colored ink40Ink normal discharge is eliminated, and a time and an amount of ink used required therefor can be reduced.

According to an aspect of the embodiments, it is possible to appropriately detect the faulty discharge of a liquid discharge head that discharges a transparent liquid onto a discharged object. Objects other than described above, configurations, and effects will be clarified by the following description of the embodiments.