JP6311242B2 - Printing apparatus, printing system, and printed matter manufacturing method - Google Patents

Description

  The present invention relates to a printing apparatus, a printing system, and a printed matter manufacturing method.

  In the conventional ink jet recording apparatus, since the shuttle system in which the head reciprocates in the width direction of a recording medium represented by paper or film is the center, it is difficult to improve the throughput by high-speed printing. Therefore, in recent years, in order to support high-speed printing, a one-pass method has been proposed in which a plurality of heads are arranged so as to cover the entire width of the recording medium and recording is performed at a time.

  However, although the 1-pass method is advantageous for increasing the speed, the time interval for ejecting adjacent dots is short, and the adjacent dots are ejected before the previously ejected ink penetrates the recording medium. However, there was a problem such as beading and bleeding, in which adjacent dots were coalesced (hereinafter referred to as droplet ejection interference) and the image quality deteriorated.

  In addition, when printing on non-penetrating media and slow-penetrating media such as film and coated paper with an ink jet printer, adjacent ink dots flow and coalesce, causing image defects such as beading and bleeding. Is also present. As a conventional technique for solving this problem, there are already known a method of taking measures by applying a pre-coating agent to the medium in advance and increasing the cohesiveness and fixing property of the ink, and a method of using UV curable ink. .

  However, in the above-described method of applying the pre-coating agent to the printing medium in advance, it is necessary to evaporate and dry the pre-coating water in addition to the ink water, which requires more drying time and a large drying apparatus. . Further, since the pre-coating agent is a supply product, it becomes a factor that increases the printing cost. Furthermore, when the treatment liquid itself is a strongly acidic liquid, its pungent odor also becomes a problem. Furthermore, in the method using the UV curable ink, the cost of the UV curable ink is higher than that of the water-based ink, which not only increases the printing cost but also causes the chemical reaction of the UV curable ink itself and fixing. Therefore, while having good weather resistance and high resistance to peeling, there is a problem that high accuracy is required for reaction control and handling becomes difficult.

  Therefore, the present invention has been made in view of the above problems, and provides a printing apparatus, a printing system, and a method for producing a printed matter that can produce a high-quality printed matter by high-speed printing without using a pre-coating liquid. The purpose is to provide.

In order to achieve the above object, a printing apparatus according to the present invention comprises a plasma processing means for acidifying at least the surface of the object to be processed by plasma processing the surface of the object to be processed, and after the plasma processing by the plasma processing means. Recording means for performing ink jet recording on the surface of the object to be processed , wherein the plasma processing means performs plasma until the viscosity of the ink applied to the surface of the object to be processed by the recording means becomes equal to or higher than a predetermined viscosity. The processing is performed .

The printing system according to the present invention includes a plasma processing apparatus that acidifies at least the surface of the processing object by plasma processing the surface of the processing object, and the surface of the processing object after the plasma processing by the plasma processing apparatus. A recording apparatus that performs ink jet recording, and the plasma processing apparatus performs plasma processing until the viscosity of the ink applied to the surface of the object to be processed by the recording unit becomes equal to or higher than a predetermined viscosity. Features.

The printed material manufacturing method according to the present invention is a manufacturing method for manufacturing a printed material on which an image is formed by inkjet recording, and at least the surface of the processed material is treated by plasma treatment. A plasma treatment step for acidification, and a recording step for performing ink jet recording on the surface of the workpiece after the plasma treatment by the plasma treatment step, wherein the plasma treatment step includes the surface of the workpiece by the recording step. The plasma treatment is performed until the viscosity of the ink applied to the ink becomes equal to or higher than a predetermined viscosity .

  According to the present invention, it is possible to provide a printing apparatus, a printing system, and a printed material manufacturing method capable of manufacturing a high-quality printed material while suppressing an increase in cost.

FIG. 1 is a diagram for explaining an example of plasma processing according to an embodiment of the present invention. FIG. 2 is a diagram illustrating a relationship example between the viscosity of the ink and the pH value of the ink according to the embodiment. FIG. 3 is a schematic diagram illustrating a schematic configuration example of the printing apparatus according to the embodiment of the present invention. FIG. 4 is a schematic diagram for explaining the outline of the acidification treatment employed in the embodiment. FIG. 5 is an enlarged view of an image obtained by imaging an image forming surface of a printed matter obtained by performing an inkjet recording process on a workpiece that has not been subjected to the plasma treatment according to the embodiment. FIG. 6 is a schematic diagram illustrating an example of dots formed on the image forming surface of the printed matter illustrated in FIG. 5. FIG. 7 is an enlarged view of an image obtained by imaging an image forming surface of a printed matter obtained by performing an inkjet recording process on a workpiece subjected to the plasma treatment according to the embodiment. FIG. 8 is a schematic diagram illustrating an example of dots formed on the image forming surface of the printed matter illustrated in FIG. 7. FIG. 9 is a graph showing the relationship between plasma energy and wettability, beading, pH value, and permeability according to the embodiment. FIG. 10 is a graph showing the relationship between plasma energy and dot diameter. FIG. 11 is a graph showing the relationship between plasma energy and the roundness of dots. FIG. 12 is a diagram showing the relationship between the plasma energy and the actually formed dot shape. FIG. 13 is a graph showing the pigment concentration of dots when the plasma treatment according to the embodiment is not performed. FIG. 14 is a graph showing the pigment concentration of dots when the plasma treatment according to the embodiment is performed. FIG. 15 is a schematic diagram illustrating details of the configuration from the plasma processing apparatus to the pattern reading unit disposed downstream of the inkjet recording apparatus in the printing apparatus according to the embodiment. FIG. 16 is a flowchart illustrating an example of a printing process including a plasma process according to the embodiment. FIG. 17 is a diagram showing an example of a table used when the ink droplet amount and the plasma energy are specified in the flowchart shown in FIG. FIG. 18 is a diagram illustrating an example of an object to be processed that has been plasma-treated in step S105 of FIG. FIG. 19 is a diagram showing an example of the test pattern formed in step S106 of FIG. FIG. 20 is a diagram illustrating another example of the test pattern. FIG. 21 is a schematic diagram illustrating an example of a pattern reading unit according to the embodiment. FIG. 22 is a diagram illustrating an example of a captured image of dots according to the embodiment. FIG. 23 is a diagram for describing a flow when the least square method is applied to the captured image illustrated in FIG. 22. FIG. 24 is a graph showing the relationship between the ink ejection amount and the image density according to the embodiment. FIG. 25 is a schematic diagram illustrating details of a configuration from a plasma processing apparatus to an inkjet recording apparatus in a printing apparatus according to a modification of the embodiment. 26 is a cross-sectional view taken along line AA of the configuration shown in FIG. FIG. 27 is a schematic diagram illustrating a configuration in which the inkjet head and the discharge electrode according to Modification 2 of the embodiment are separately provided. FIG. 28 is a top view showing the image forming area and the plasma processing area in FIG. FIG. 29 is a schematic diagram illustrating a configuration during plasma processing of the plasma processing apparatus according to the second modification of the embodiment. FIG. 30 is a schematic diagram illustrating a configuration of the plasma processing apparatus according to the second modification of the embodiment when a workpiece is conveyed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described in detail with reference to the accompanying drawings. The embodiments described below are preferred embodiments of the present invention, and thus various technically preferable limitations are given. However, the scope of the present invention is unduly limited by the following description. However, not all the configurations described in the present embodiment are essential constituent elements of the present invention.

  In the following embodiments, the surface of an object to be processed is acidified in order to aggregate the pigment while preventing the dispersion of the ink pigment immediately after the ink has landed on the object to be processed (also referred to as a recording medium or a print medium). Examples of the acidifying means include plasma treatment.

  In the following embodiments, the trueness of ink dots (hereinafter simply referred to as dots) is controlled by controlling the wettability of the surface of the plasma-treated object and the cohesiveness and penetrability of the ink pigment due to a decrease in pH value. In addition to improving the circularity, dot unification is prevented and the sharpness and color gamut of the dot are expanded. Thereby, image defects such as beading and bleeding can be solved, and a printed matter on which a high-quality image is formed can be obtained. In addition, by making the aggregate thickness of the pigment on the object to be processed thin and uniform, it is possible to reduce the ink droplet amount, thereby reducing the ink drying energy and the printing cost.

In the plasma treatment as the acidification treatment means (process), the treatment object is irradiated with plasma in the air to react the polymer on the treatment object surface to form a hydrophilic functional group. Specifically, as shown in FIG. 1, the electrons e emitted from the discharge electrode are accelerated in an electric field to excite and ionize atoms and molecules in the atmosphere. Electrons are also emitted from ionized atoms and molecules, increasing the number of high-energy electrons, and as a result, streamer discharge (plasma) is generated. Due to the high energy electrons generated by the streamer discharge, polymer bonds on the surface of the object to be treated 20 (for example, coated paper) (the coated layer 21 of the coated paper is hardened with starch as calcium carbonate and a binder. Which has a structure) and is recombined with oxygen radicals O ^* and ozone O ₃ in the gas phase. Thereby, polar functional groups, such as a hydroxyl group and a carboxyl group, are formed on the surface of the workpiece 20. As a result, hydrophilicity and acidification are imparted to the surface of the workpiece 20.

  In order to prevent color mixing between the dots by adhering the dots that are adjacent on the object to be processed by wetting and spreading due to increased hydrophilicity, a colorant (for example, pigment or dye) is added within the dots. It has also been found that it is important to agglomerate and to allow the vehicle to dry and penetrate into the workpiece faster than the vehicle wets and spreads. Therefore, in the following embodiment, in order to agglomerate the colorant or infiltrate the vehicle into the object to be processed, an acidification process for acidifying the surface of the object to be processed is performed as a pre-process of the ink jet recording process. To do.

  Acidification in this description means lowering the pH value of the print medium surface to a pH value at which the pigment contained in the ink aggregates. Lowering the pH value means increasing the hydrogen ion H + concentration in the object. The pigment in the ink before touching the surface of the object to be processed is negatively charged, and the pigment is dispersed in the vehicle. FIG. 2 shows an example of the relationship between the ink pH value and the ink viscosity. As shown in FIG. 2, the viscosity of the ink increases as the pH value decreases. This is because as the acidity of the ink increases, the negatively charged pigment in the ink vehicle is electrically neutralized, resulting in aggregation of the pigments. Therefore, for example, in the graph shown in FIG. 2, the ink viscosity can be increased by lowering the pH value of the surface of the print medium so that the ink pH value corresponds to the required viscosity. This is because when the ink adheres to the acidic print medium surface, the pigments aggregate as a result of the electrical neutralization of the pigment by hydrogen ions H + on the print medium surface. Accordingly, it is possible to prevent color mixing between adjacent dots and to prevent the pigment from penetrating deeply into the printing medium (and further to the back surface). However, in order to lower the pH value of the ink so as to obtain a pH value corresponding to the required viscosity, the pH value of the surface of the printing medium needs to be lower than the pH value of the ink corresponding to the required viscosity. .

  Further, the pH value for making the ink have a necessary viscosity varies depending on the characteristics of the ink. That is, as shown in ink A in FIG. 2, there is an ink whose viscosity increases due to agglomeration of the pigment at a pH value relatively close to neutrality, and as shown in ink B having different characteristics from ink A, the pigment In some inks, a pH value lower than that of the ink A is required in order to cause aggregation.

  The behavior of the colorant agglomerating within the dots, the drying speed of the vehicle and the penetration speed into the object to be treated are the amount of droplets that change depending on the size of the dots (small droplets, medium droplets, large droplets) It depends on the type. Therefore, in the following embodiments, the plasma energy in the plasma processing may be controlled to an optimum value according to the type of the object to be processed and the printing mode (droplet amount).

  Next, a printing apparatus, a printing system, and a printed matter manufacturing method according to an embodiment of the present invention will be described in detail with reference to the drawings.

  In this embodiment, an image forming apparatus having four color ejection heads (recording head and ink head) of black (K), cyan (C), magenta (M), and yellow (Y) will be described. It is not limited to the discharge head. That is, you may have further the discharge head corresponding to green (G), red (R), and another color, and you may have the discharge head only of black (K). In the following description, K, C, M, and Y correspond to black, cyan, magenta, and yellow, respectively.

  In this embodiment, continuous paper wound in a roll shape (hereinafter referred to as roll paper) is used as an object to be processed. However, the present invention is not limited to this. For example, a recording medium that can form an image such as cut paper. If it is. In the case of paper, for example, plain paper, high-quality paper, recycled paper, thin paper, thick paper, coated paper, and the like can be used. In addition, an OHP sheet, a synthetic resin film, a metal thin film, and other materials capable of forming an image with ink or the like on the surface can also be used as a processing object. In the case where the object to be processed is a non-penetrating paper such as a coated paper and a slow-penetrating paper, this embodiment is more effective. Here, the roll paper may be continuous paper (continuous form paper, continuous form) in which cuttable perforations are formed at predetermined intervals. In this case, the page (page) on the roll paper is, for example, an area sandwiched between perforations at a predetermined interval.

  As shown in FIG. 3, the printing apparatus (system) 1 is configured to carry in (convey) the workpiece 20 (roll paper) along the conveyance path D <b> 1, and to the workpiece 20 that has been carried in. It has a plasma processing apparatus 100 that performs plasma processing as pre-processing, and an image forming unit 40 that forms an image on the surface of the plasma-processed object 20. The image forming unit 40 can include an inkjet head 170 that forms an image on the workpiece 20 that has been plasma-treated by inkjet processing, and a pattern reading unit 180 that reads an image formed on the workpiece 20. Further, the image forming unit 40 may include a post-processing unit that post-processes the workpiece 20 on which an image is formed. Furthermore, the printing apparatus (system) 1 includes a drying unit 50 that dries the processed object 20 that has been post-processed, and a carry-out unit 60 that carries out the processed object 20 that has been image-formed (and further post-processed in some cases). You may have. The pattern reading unit 180 may be provided at a position downstream of the drying unit 50 on the transport path D1. Furthermore, the printing apparatus (system) 1 includes a control unit (not shown) that controls the operation of each unit. This control unit may be connected to a print control device that generates raster data from image data to be printed, for example. The print control apparatus may be provided inside the printing apparatus (system) 1 or may be provided outside via a network such as the Internet or a LAN (Local Area Network).

  In the embodiment, as described above, in the printing apparatus (system) 1 illustrated in FIG. 3, an acidification process for acidifying the surface of the object to be processed is performed before the ink jet recording process. For this acidification treatment, for example, atmospheric pressure non-equilibrium plasma treatment using dielectric barrier discharge can be employed. The acidification treatment using atmospheric pressure non-equilibrium plasma is one of the preferable plasma treatment methods for an object to be processed such as a recording medium because the electron temperature is extremely high and the gas temperature is around room temperature.

  In order to stably generate the atmospheric pressure non-equilibrium plasma in a wide range, it is preferable to execute an atmospheric pressure non-equilibrium plasma treatment employing a streamer dielectric breakdown type dielectric barrier discharge. Streamer dielectric breakdown type dielectric barrier discharge can be obtained, for example, by applying an alternating high voltage between electrodes coated with a dielectric.

  As a method for generating atmospheric pressure non-equilibrium plasma, various methods can be used in addition to the above-described streamer dielectric breakdown type dielectric barrier discharge. For example, it is possible to apply a dielectric barrier discharge in which an insulator such as a dielectric is inserted between electrodes, a corona discharge that forms a significant non-uniform electric field on a thin metal wire, or a pulse discharge that applies a short pulse voltage. is there. It is also possible to combine two or more of these methods.

  FIG. 4 is a schematic diagram for explaining the outline of the acidification treatment employed in the embodiment. As shown in FIG. 4, the plasma treatment apparatus 10 including the discharge electrode 11, the ground electrode 14, the dielectric 12, and the high-frequency and high-voltage power supply 15 is used for the acidification treatment employed in the embodiment. In the plasma processing apparatus 10, the dielectric 12 is disposed between the discharge electrode 11 and the ground electrode 14. The high frequency high voltage power source 15 applies a high frequency / high voltage pulse voltage between the discharge electrode 11 and the ground electrode 14. The voltage value of this pulse voltage is about 10 kV (kilovolt), for example. Moreover, the frequency can be about 20 kHz (kilohertz), for example. By supplying such a high-frequency / high-voltage pulse voltage between the two electrodes, an atmospheric pressure non-equilibrium plasma 13 is generated between the discharge electrode 11 and the dielectric 12. The workpiece 20 passes between the discharge electrode 11 and the dielectric 12 while the atmospheric pressure non-equilibrium plasma 13 is generated. Thereby, the surface of the workpiece 20 on the discharge electrode 11 side is subjected to plasma treatment.

  In the plasma processing apparatus 10 illustrated in FIG. 4, a rotary discharge electrode 11 and a belt conveyor type dielectric 12 are employed. The workpiece 20 passes through the atmospheric pressure non-equilibrium plasma 13 by being nipped and conveyed between the rotating discharge electrode 11 and the dielectric 12. As a result, the surface of the workpiece 20 comes into contact with the atmospheric pressure non-equilibrium plasma 13 and is subjected to uniform plasma processing.

  Here, with reference to FIGS. 5 to 8, the difference in printed matter between the case where the plasma treatment according to the embodiment is performed and the case where the plasma treatment is not performed will be described. FIG. 5 is an enlarged view of an image obtained by imaging an image forming surface of a printed matter obtained by performing an inkjet recording process on an object that has not been subjected to the plasma treatment according to the embodiment. 6 is a schematic diagram illustrating an example of dots formed on the image forming surface of the printed matter illustrated in FIG. 5. FIG. 7 is an enlarged view of an image obtained by imaging an image forming surface of a printed matter obtained by performing the inkjet recording process on the workpiece subjected to the plasma treatment according to the embodiment. FIG. 8 is a schematic diagram illustrating an example of dots formed on the image forming surface of the printed matter illustrated in FIG. 7. In order to obtain the printed matter shown in FIGS. 5 and 7, a desktop type ink jet recording apparatus was used. Moreover, the general coated paper provided with the coating layer 21 (refer FIG. 1) was used for the to-be-processed object 20. FIG.

  In the coated paper not subjected to the plasma treatment according to the embodiment, the wettability of the coated layer 21 on the coated paper surface is poor. For this reason, in an image formed by inkjet recording processing on coated paper that has not been subjected to plasma processing, for example, as shown in FIG. 5 and FIG. The shape of CT1 is distorted. In addition, when the surface wettability is poor, the dots have a high shape due to the surface tension of the vehicle CT1, and a relatively long time is required for drying. When the proximity dots are formed in a state where the dots are not sufficiently dried, as shown in FIGS. 5 and 6, when the proximity dots land on the coated paper, the vehicles CT1 and CT2 are united with each other. Further, movement (mixed color) of P2 occurs, and as a result, density unevenness due to beading or the like may occur.

  On the other hand, the coated paper subjected to the plasma treatment according to the embodiment has improved wettability of the coated layer 21 on the surface of the coated paper. Therefore, in an image formed by inkjet recording processing on coated paper that has been subjected to plasma processing, for example, as shown in FIG. 7, vehicle CT1 spreads in a relatively flat perfect circle on the surface of the coated paper. As a result, the dots have a flat shape as shown in FIG. Further, since the coated paper surface becomes acidic due to the polar functional group formed by the plasma treatment, the ink pigment is electrically neutralized, and the pigment P1 is aggregated to increase the viscosity of the ink. Accordingly, even when the vehicles CT1 and CT2 are united as shown in FIG. 8, the movement (color mixing) of the pigments P1 and P2 between the dots is suppressed. Furthermore, since polar functional groups are also generated inside the coat layer 21, the permeability of the vehicle CT1 is increased. As a result, the vehicle penetrates into the workpiece 20 and can be dried in a relatively short time. Dots that spread in a perfect circle due to improved wettability aggregate while penetrating, whereby the pigment P1 is evenly aggregated in the height direction, and density unevenness due to beading or the like can be suppressed. FIGS. 6 and 8 are schematic diagrams. Actually, in the case of FIG. 8 as well, the pigment is agglomerated in layers.

  Thus, in the to-be-processed object 20 which performed the plasma processing concerning embodiment, as a result of forming a polar functional group by plasma processing, the surface becomes acidic. As a result, the negatively charged pigment is neutralized on the surface of the object to be processed 20, so that the pigment aggregates to increase the viscosity, and even if the dots are united, the movement of the pigment can be suppressed. It becomes. Moreover, the polar functional group is also generated inside the coating layer 21 formed on the surface of the object to be processed 20, so that the vehicle quickly penetrates into the object to be processed 20, thereby shortening the drying time. I can do it. In other words, the dots spreading in a perfect circle due to the increase in wettability can maintain a shape close to a perfect circle by penetrating in a state where the movement of the pigment is suppressed by aggregation.

  FIG. 9 is a graph showing the relationship between plasma energy and wettability, beading, pH value, and permeability of the surface of the workpiece according to the embodiment. In FIG. 9, how the surface characteristics (wetting, beading, pH value, permeability (liquid absorption characteristics)) when printed on the coated paper as the object to be treated 20 change depending on the plasma energy. It is shown. In order to obtain the evaluation shown in FIG. 9, an aqueous pigment ink (an alkaline ink in which a negatively charged pigment is dispersed) having a characteristic that the pigment aggregates with an acid was used as the ink.

As shown in FIG. 9, the wettability of the coated paper surface improves rapidly when the plasma energy is low (for example, about 0.2 J / cm ² or less), and does not improve much even if the energy is increased further. On the other hand, the pH value of the coated paper surface decreases to a certain extent by increasing the plasma energy. However, when the plasma energy exceeds a certain value (for example, about 4 J / cm ² ), it becomes saturated. Further, the permeability (liquid absorption characteristic) has been improved rapidly from the point where the decrease in pH is saturated (for example, about 4 J / cm ² ). However, this phenomenon differs depending on the polymer component contained in the ink.

As a result, the value of beading (granularity) is in a very good state since the permeability (liquid absorption characteristic) starts to improve (for example, about 4 J / cm ² ). The beading (granularity) here is a numerical value representing the roughness of the image, and is a standard deviation of the average density. In FIG. 9, a plurality of densities of a solid image of a color composed of two or more dots are sampled, and the standard deviation of the densities is represented as beading (granularity). As described above, since the ink ejected onto the coated paper subjected to the plasma treatment according to the first embodiment spreads in a perfect circle and penetrates while being aggregated, image beading (granularity) is improved.

  As described above, in the relationship between the characteristics of the surface of the workpiece 20 and the image quality, the roundness of the dots is improved by improving the wettability of the surface. This is because the hydrophilic polar functional group generated by the plasma treatment improves the wettability of the surface of the workpiece 20 and makes it uniform, and in addition, water repellent factors such as dust, oil and calcium carbonate are present. This is probably because it was excluded by the plasma treatment. As a result of improving the wettability of the surface of the workpiece 20, the droplets spread evenly in the circumferential direction and the roundness of the dots is improved.

  Further, by acidifying the surface of the object to be treated 20 (decreasing pH), aggregation of the ink pigment, improvement of permeability, penetration of the vehicle into the coating layer, and the like occur. As a result, the pigment concentration on the surface of the object to be treated 20 increases, so that even if the dots are united, it is possible to suppress the movement of the pigment. As a result, the turbidity of the pigment is suppressed, and the pigment is uniformly treated. It becomes possible to settle and aggregate on the surface of the object. However, the effect of suppressing the pigment turbidity varies depending on the ink components and the ink droplet amount. For example, when the appropriate amount of ink is small droplets, pigment turbidity due to coalescence of dots is less likely to occur than when large droplets are used. This is because when the amount of the vehicle is small droplets, the vehicle dries and penetrates faster, and the pigment can be aggregated with a little pH reaction. Note that the effect of the plasma treatment varies depending on the type and environment (humidity, etc.) of the workpiece 20. Therefore, by setting the plasma energy at the time of the plasma processing to an optimum value, the surface modification efficiency of the workpiece 20 is improved, so that further energy saving can be achieved.

  Here, the relationship between the plasma energy and the roundness of the dots will be described. FIG. 10 is a graph showing the relationship between plasma energy and dot diameter. FIG. 11 is a graph showing the relationship between plasma energy and the roundness of dots. FIG. 12 is a diagram showing the relationship between the plasma energy and the actually formed dot shape.

  As shown in FIG. 10, when the plasma energy is increased, the dot diameter tends to decrease for any of CMYK pigments. As a result of the plasma treatment, the pigment agglomeration effect (increase in viscosity due to agglomeration) and penetrability effect (penetration of the vehicle into the coating layer) are improved. This is thought to be due to penetration. By utilizing such an effect, the dot diameter can be controlled. That is, the dot diameter can be controlled by controlling the plasma energy.

Further, as shown in FIGS. 11 and 12, the roundness of the dot is greatly improved even when the plasma energy is a low value (for example, about 0.2 J / cm ² or less). As described above, it is considered that the plasma treatment of the workpiece 20 increases the viscosity of the dots (vehicles) and increases the permeability of the vehicle, thereby causing the pigments to aggregate uniformly.

  Next, the dot pigment concentration when the plasma treatment is performed and the dot pigment concentration when the plasma treatment is not performed will be described. FIG. 13 is a graph showing the pigment concentration of dots when the plasma treatment according to the embodiment is not performed. FIG. 14 is a graph showing the pigment concentration of dots when the plasma treatment according to the embodiment is performed. 13 and 14 show the densities on the line segment ab in the dot image at the lower right in the drawing.

  In the measurement of FIG. 13 and FIG. 14, an image of the formed dots was captured, density unevenness in the image was measured, and density variation was calculated. As is clear from comparison between FIG. 13 and FIG. 14, when the plasma treatment is performed (FIG. 14), the density variation (density difference) can be made smaller than when the plasma treatment is not performed (FIG. 13). did it. Therefore, the plasma energy in the plasma processing may be optimized so as to minimize the variation (concentration difference) based on the variation in concentration obtained by the above calculation method. This makes it possible to form a clearer image.

  The variation in density is not limited to the calculation method described above, and may be calculated by measuring the thickness of the pigment with a light interference film thickness measuring unit. In that case, an optimum value of the plasma energy may be selected so as to minimize the deviation of the pigment thickness.

  Next, the printing apparatus (system) 1 according to the embodiment will be described in more detail. In the printing apparatus (system) 1, a pattern reading unit that acquires an image of the formed dots is provided on the downstream side of the inkjet recording unit. Further, the acquired image is analyzed to calculate dot roundness, dot diameter, density variation, and the like, and the plasma processing means is feedback-controlled or feedforward-controlled based on the results. FIG. 15 shows details of the configuration from the plasma processing apparatus to the pattern reading unit arranged downstream of the ink jet recording apparatus in the printing apparatus according to the embodiment. Since the other configuration is the same as that of the printing apparatus (system) 1 shown in FIG. 3, detailed description thereof is omitted here.

  As shown in FIG. 15, the printing apparatus (system) 1 includes a plasma processing apparatus 100 disposed on the upstream side of the transport path D1, and an inkjet head 170 disposed on the downstream side of the plasma processing apparatus 100 in the transport path D1. And a pattern reading unit 180 disposed on the downstream side of the ink jet head 170 and a control unit 160 for controlling each unit of the plasma processing apparatus 100. The ink-jet head 170 forms an image by ejecting ink onto the workpiece 20 whose surface is plasma-treated by the plasma processing apparatus 100 disposed on the upstream side. The ink jet head 170 may be controlled by a separately provided control unit (not shown) or may be controlled by the control unit 160.

  The plasma processing apparatus 100 includes a plurality of discharge electrodes 111 to 116 arranged along the transfer path D1, a high-frequency and high-voltage power supply 151 to 156 that supplies high-frequency / high-voltage pulse voltages to the discharge electrodes 111 to 116, a plurality of The ground electrode 141 provided in common with respect to the discharge electrodes 111 to 116, and the endless belt conveyor type disposed so as to flow along the transport path D1 between the discharge electrodes 111 to 116 and the installation electrode 141. The dielectric 121 and the roller 122 are provided. When using the plurality of discharge electrodes 111 to 116 arranged along the transport path D1, it is preferable to use an endless belt for the dielectric 121 as shown in FIG.

  The controller 160 circulates the dielectric 121 by driving the roller 122 based on an instruction from a host device (not shown). When the workpiece 20 is loaded onto the dielectric 121 from the upstream loading section 30 (see FIG. 3), the workpiece 20 passes through the conveyance path D <b> 1 due to the circulation of the dielectric 121.

  The high-frequency and high-voltage power supplies 151 to 156 supply high-frequency and high-voltage pulse voltages to the discharge electrodes 111 to 116 in accordance with instructions from the control unit 160, respectively. The pulse voltage may be supplied to all of the discharge electrodes 111 to 116, or supplied to the number of discharge electrodes necessary to bring the surface of the workpiece 20 out of the discharge electrodes 111 to 116 below a predetermined pH value. May be. Alternatively, the control unit 160 sets the frequency and voltage value (corresponding to plasma energy, hereinafter referred to as plasma energy) of the pulse voltage supplied from each of the high-frequency and high-voltage power supplies 151 to 156 to a predetermined pH value on the surface of the workpiece 20. You may adjust to the plasma energy required for the following.

  The pattern reading unit 180 captures dots of an image formed on the workpiece 20, for example. Note that the image formed on the workpiece 20 may be a test pattern for dot analysis. In the following description, the case of a test pattern will be described as an example.

  The image acquired by the pattern reading unit 180 is input to the control unit 160. The controller 160 analyzes the input image to calculate the roundness, dot diameter, density variation, etc. of the dots in the test pattern, and based on the calculation results, the discharge electrodes 111 to 116 to be driven are calculated. The number and / or the plasma energy of the pulse voltage supplied to each discharge electrode 111-116 from each high frequency high voltage power supply 151-156 is adjusted.

  Here, as one method for obtaining plasma energy necessary for sufficiently and sufficiently plasma-treating the surface of the workpiece 20, it is conceivable to lengthen the plasma treatment time. This can be realized, for example, by reducing the conveyance speed of the workpiece 20. However, when image recording is performed on the workpiece 20 at high speed, it is desirable to shorten the plasma processing time. As a method of shortening the plasma processing time, as described above, a plurality of discharge electrodes 111 to 116 are provided, and a necessary number of discharge electrodes 111 to 116 are driven according to a printing speed and necessary plasma energy, A method of adjusting the intensity of plasma energy applied to the discharge electrodes 111 to 116 is conceivable. However, the present invention is not limited to these, and it is possible to appropriately change methods such as a combination of these methods and other methods.

  As shown in FIG. 15, the inkjet head 170 may include a plurality of the same color heads (4 colors × 4 heads). This makes it possible to speed up the inkjet recording process. At that time, for example, in order to achieve a resolution of 1200 dpi at high speed, the heads of the respective colors in the inkjet head 170 are fixed while being shifted so as to correct the interval between the nozzles that eject ink. Furthermore, each color head is supplied with drive pulses with several variations so that the ink dots ejected from the nozzle correspond to three types of capacities called large / medium / small droplets. Is done.

  The controller 160 can individually turn on / off the plurality of high-frequency and high-voltage power supplies 151 to 156. For example, the controller 160 selects the number of high-frequency and high-voltage power supplies 151 to 156 in proportion to the printing speed information, The intensity of the plasma energy of the pulse voltage applied to the electrodes 111 to 116 is adjusted. In addition, the control unit 160 controls the number of high-frequency and high-voltage power supplies 151 to 156 and / or plasma energy applied to the discharge electrodes 111 to 116 according to the type of the workpiece 20 (for example, coated paper or PET film). May be adjusted.

  In addition, providing the plurality of discharge electrodes 111 to 116 is also effective in uniformly plasma-treating the surface of the workpiece 20. That is, for example, when the same conveyance speed (or printing speed) is used, the workpiece 20 passes through the plasma space when the plasma treatment is performed with a plurality of discharge electrodes rather than when the plasma treatment is performed with one discharge electrode. It becomes possible to lengthen the time to do. As a result, the surface of the workpiece 20 can be more uniformly subjected to plasma treatment.

  Next, printing processing including plasma processing according to the embodiment will be described in detail with reference to the drawings. FIG. 16 is a flowchart illustrating an example of a printing process including a plasma process according to the embodiment. FIG. 17 is a diagram showing an example of a table used when the ink droplet amount and the plasma energy are specified in the flowchart shown in FIG. 16 exemplifies a case where a cut sheet (a recording medium cut to a predetermined size) is printed as the workpiece 20 by using the printing apparatus (system) 1 shown in FIG. The same printing process can be applied not only to cut paper but also to roll paper wound in a roll shape.

  As shown in FIG. 16, in the printing process, first, the control unit 160 specifies the type (paper type) of the workpiece 20 (step S101). The type (paper type) of the workpiece 20 may be set and input to the printing apparatus (system) 1 by a user from a control panel (not shown). Alternatively, the printing apparatus (system) 1 may include a paper type detection unit (not shown), and the control unit 160 may specify based on the paper type information detected by the paper type detection unit. Note that the paper type detection means may be one that, for example, irradiates the paper surface with laser light and analyzes the interference spectrum of the reflected light to identify the type. In addition, the control unit 160 specifies the print mode (step S102). The print mode is, for example, the resolution (600 dpi, 1200 dpi, etc.) of the image of the printed matter, and may be set by the user using an input unit (not shown), for example. The print mode may include black and white printing and color printing.

  Next, the control unit 160 specifies the ink droplet amount at the time of image formation (step S103). The ink droplet amount can be specified from a table as shown in FIG. 17 based on the specified printing mode and dot size, for example. For example, when the printing mode is 1200 dpi and the dot size is a small droplet, the ink droplet amount can be specified as 2 pl (picoliter) based on the table shown in FIG. When the print mode is 600 dpi and the dot size is a large droplet, the ink droplet amount can be specified as 15 pl (picoliter). The dot size is the size of droplets ejected from the inkjet head 170 or the size of dots formed on the object 20 to be processed, and may be specified by the control unit 160 from the image information to be printed.

Subsequently, the control unit 160 sets plasma energy at the time of plasma processing (step S104). The plasma energy can be specified from a table as shown in FIG. 17 based on the specified type (paper type) of the processing object 20 and the ink droplet amount. For example, when the type of the processing object 20 is coated paper A and the ink droplet amount is 6 pl, the control unit 160 sets the plasma energy to 0.7 J / cm ² . In the table shown in FIG. 17, the value of plasma energy is registered. However, the present invention is not limited to this. May be. In the table shown in FIG. 17, the plasma energy may be registered so as to be changed according to the black and white printing mode and the color printing mode. Furthermore, the table shown in FIG. 17 may be divided into a part used in step S103 and a part used in step S104.

  Next, the control part 160 performs the plasma process with respect to the to-be-processed object 20 by supplying a pulse voltage to the discharge electrodes 111-116 suitably from the high frequency high voltage power supplies 151-156 based on the set plasma energy (step S105). ). Subsequently, the control unit 160 prints a test pattern on the workpiece 20 after the plasma processing (step S106). Subsequently, the control unit 160 reads the dot image (dot image) formed on the workpiece 20 after the plasma processing by imaging the dots of the test pattern using the pattern reading unit 180 (step S107). .

  Next, the control unit 160 calculates the roundness of the dot (step S108), the dot diameter (step S109), and the deviation (variation, density difference) of the pigment density in the dot (step S110) from the read dot image. Detect each. Further, the control unit 160 may determine the state of unity between dots from the read dot image. The unity state between the dots can be determined by pattern recognition, for example.

  Next, the control unit 160 has a sufficient quality of the formed dots based on the detected roundness of the dots, the dot diameter, and the deviation of the pigment density in the dots (and the state of dot coalescence). Whether or not (step S111). When the quality is not sufficient (step S111; NO), the control unit 160 corrects the plasma energy according to the detected roundness of the dot, the dot diameter, and the deviation of the pigment concentration in the dot (and the dot coalescence state). Then (step S112), the process returns to step S105, and the dot analysis is executed again from the test pattern printing. For this correction, for example, the plasma energy being set may be increased or decreased by a predetermined amount of correction value set in advance, or the roundness of the detected dot, the dot diameter, and the deviation of the pigment concentration in the dot (and the dot density) The optimum plasma energy may be obtained according to the (unified state) and reset to this value.

  On the other hand, when the dots have sufficient quality (step S111; YES), the control unit 160 registers the plasma registered in FIG. 17 based on the specified type (paper type) of the workpiece 20 and the printing mode. The energy is updated (step S113), the actual image to be printed is printed (step S114), and this operation is terminated as soon as it is completed.

  When roll paper is used as the object to be processed 20, in steps S <b> 105 to S <b> 112, a dot image formed after plasma processing may be acquired using the leading end portion of the paper guided from a paper supply device (not shown). . In the case of using roll paper, the property hardly changes with one roll. Therefore, after adjusting the plasma energy using the tip portion, it is possible to perform continuous printing stably with the setting as it is. However, if the roll paper is used up for a long period of time without being used up, the properties of the paper may change. Can be analyzed. Alternatively, after adjusting the plasma energy by analyzing the dot image formed after the plasma processing using the tip portion, the plasma energy may be adjusted by measuring the dot image periodically or continuously. As a result, more detailed and stable control can be performed.

  In FIG. 16, the table shown in FIG. 17 is used. However, the present invention is not limited to this method. For example, the initial plasma energy is set to the minimum value and the obtained test pattern dot image is analyzed. The plasma energy may be increased step by step.

When the plasma energy is increased stepwise from the minimum value, the plasma energy applied to each of the discharge electrodes 111 to 116 in FIG. 15 may be changed from the downstream side so as to increase stepwise. The conveyance speed of 20, that is, the circulation speed of the dielectric 121 may be changed. As a result, in step S105 of FIG. 16, as shown in FIG. 18, it is possible to obtain a workpiece 20 that has been plasma-treated with different plasma energy for each region. In FIG. 18, the region R1 is a region where the plasma treatment is not performed (plasma energy = 0 J / cm ² ), and the region R2 is a region where the plasma treatment is performed with a plasma energy of 0.1 J / cm ^2. R3 represents a plasma processing region in a plasma energy of 0.5 J / cm ^2, region R4 represents a plasma processing region in a plasma energy of 2J / cm ^2, region R5 is a plasma energy of 5 J / cm ² The plasma treated area is shown.

  Further, for the workpiece 20 that is plasma-treated with different plasma energy for each region as shown in FIG. 18, for example, a common test including a plurality of dots having different dot diameters as shown in FIG. The pattern TP may be formed in each of the regions R1 to R5 in step S106 of FIG. Further, the test pattern TP shown in FIG. 19 may be replaced with a test pattern TP1 including a plurality of dots having different dot diameters for each CMYK as shown in FIG.

  The test pattern TP formed as described above is read by the pattern reading unit 180 in FIG. 15 in step S107 in FIG. Here, FIG. 21 shows an example of the pattern reading unit 180 according to the embodiment.

  As shown in FIG. 21, for the pattern reading unit 180, for example, a reflective two-dimensional sensor including a light emitting unit 182 and a light receiving unit 183 is used. The light emitting unit 182 and the light receiving unit 183 are disposed, for example, in a housing 181 that is disposed on the dot forming side with respect to the workpiece 20. An opening is provided on the object to be processed 20 side of the housing 181, and light emitted from the light emitting unit 182 is reflected by the surface of the object to be processed 20 and enters the light receiving unit 183. The light receiving unit 183 forms an image of the reflected light amount (reflected light intensity) reflected by the surface of the workpiece 20. Since the amount of light (intensity) of the reflected light that has been imaged changes between the portion with printing (dot DT of the test pattern TP) and the portion without printing, the amount of reflected light (reflected light intensity) detected by the light receiving unit 183 is used. In addition, it is possible to detect the dot shape and the image density inside the dot. The configuration of the pattern reading unit 180 and the detection method thereof can be variously changed as long as the test pattern TP printed on the workpiece 20 can be detected.

  Further, the pattern reading unit 180 may include a reference pattern display unit 184 including a reference pattern 185 as means for calibrating the light amount of the light emitting unit 182 and the read voltage of the light receiving unit 183. The reference pattern display unit 184 has a rectangular parallelepiped shape made of, for example, a predetermined object (for example, plain paper), and the reference pattern 185 is pasted on one surface thereof. When the calibration of the light emitting unit 182 and the light receiving unit 183 is performed, the reference pattern display unit 184 rotates so that the reference pattern 185 faces the light emitting unit 182 and the light receiving unit 183 side. When the calibration is not performed, the reference pattern 185 is displayed. Is inverted so as not to face the light emitting unit 182 and the light receiving unit 183 side. The reference pattern 185 may have the same shape as the test pattern TP or TP1 as shown in FIG. 19 or 20, for example.

  In the embodiment, the case where the plasma energy is adjusted based on the analysis result of the dot image acquired using the pattern reading unit 180 is exemplified, but the present invention is not limited to this. For example, in step S106 in FIG. The user may be configured to set the plasma energy based on the test pattern TP formed on the workpiece 20.

  Next, an example of a method for determining the dot size of the test pattern formed on the workpiece 20 will be described with reference to the drawings. In order to determine the dot size of the test pattern, the test pattern TP or TP1 as shown in FIG. 19 or FIG. 20 is recorded on the workpiece 20 after the plasma processing, and the pattern reading unit 180 uses this test pattern TP. Alternatively, by capturing images of TP1 and the reference pattern 185, a captured image (dot image) of dots as shown in FIG. 22 is acquired. It is assumed that the position of the reference pattern 185 is previously determined by measurement to determine which position is in the entire imaging region (two-dimensional sensor total imaging region) of the light receiving unit 183 shown in FIG. The control unit 160 compares the acquired dot image pixel of the test pattern TP or TP1 with the dot image pixel of the reference pattern 185, thereby calibrating the dot image of the test pattern TP or TP1. At this time, for example, as shown in FIG. 22, there is a figure that is not completely a circle but is a circle (for example, the outline of the dot of the test pattern TP or TP1: solid line). The fitting is performed using a dot outline (dotted line), and the least square method is used for this fitting.

As shown in FIG. 23, in the least square method, in order to quantify the deviation between a circle-like figure (solid line) and a perfect circle (one-dot broken line), an origin O is taken at a rough center position, and this origin O Is set as a reference, and finally the optimum center point A (coordinates (a, b)) and the radius R of the perfect circle are obtained. Therefore, first, a circle (2π) of a figure such as a circle is equally divided based on the angle, and for each of the data points P1 to Pn obtained by this division, the angle θ _i with respect to the X axis and the distance from the origin O ρ _i is obtained. Here, if the number of data points (that is, the number of data sets) is 'N', the following equation (1) can be derived from the relationship of trigonometric functions.

At this time, the optimum center point A (coordinates (a, b)) and the radius R of the perfect circle are given by the following equation (2).

  In this way, the dot image of the reference pattern 185 is read, and the calibration is performed by comparing the diameter of the dot diameter calculated by the least square method with the diameter of the reference chart. After calibration, a dot image printed with a pattern is read, and the dot diameter is calculated.

  In addition, the roundness is generally expressed as the difference between the radii of two concentric circles when the interval between the concentric circles is minimized when a figure like a circle is sandwiched between two concentric geometric circles. The ratio of minimum diameter / maximum diameter in concentric circles can also be defined as roundness. In this case, the case where the value of the minimum diameter / maximum diameter is “1” means a perfect circle. This roundness can also be calculated by the least square method by capturing a dot image.

  The maximum diameter can be obtained as the maximum distance when connecting the dot center of the captured image and each point on the circumference. On the other hand, the minimum diameter can be calculated as the minimum distance when connecting the dot center point and each point on the circumference.

  Depending on the ink permeation state of the workpiece 20, the dot diameter and the roundness of the dot are different. In the present embodiment, the image quality is improved by controlling the dot shape (roundness) and the dot diameter to the target values according to the type of the processing object 20 and the ink ejection amount. To do. Further, in the present embodiment, by reading the formed image and analyzing the image, by adjusting the plasma energy in the plasma processing so that the dot diameter for each ink ejection amount becomes the target dot diameter, We are trying to improve image quality.

  In this embodiment, since the pigment density of a dot can be detected based on the amount of reflected light, a dot image is captured and the density inside the dot is measured. The density unevenness is measured by calculating the density value as variation dispersion by statistical calculation. In addition, by selecting the plasma energy so that the calculated density unevenness is minimized, it becomes possible to prevent the turbidity of the pigment due to the coalescence of dots, thereby further improving the image quality. Whether priority is given to dot diameter control, suppression of density unevenness, or improvement of roundness, priority can be given to the user according to the desired image quality. Good.

  As described above, in the embodiment, the plasma energy is controlled so that the roundness of the dots or the unevenness of the pigment in the dots is reduced, or the dot diameter becomes a target size. Thereby, it becomes possible to provide a high-quality printed product without using a pre-coating liquid. In addition, even if the properties of the object to be processed are changed or the printing speed is changed, stable plasma processing can be performed, so that good image recording can be realized stably.

  In the above-described embodiment, the case where the plasma processing is mainly performed on the processing object has been described. However, as described above, when the plasma processing is performed, the wettability of the ink with respect to the processing object is improved. As a result, since the dots to be attached during ink jet recording are expanded, there is a possibility that an image different from the case where an image is developed on an unprocessed object is recorded. Therefore, when printing on a plasma-treated recording medium, for example, it is possible to cope with the problem by reducing the ink droplet voltage by reducing the ink ejection voltage when performing ink jet recording. As a result, it is possible to reduce the amount of ink droplets, thereby reducing the cost.

  FIG. 24 is a graph showing the relationship between the ink ejection amount and the image density according to the embodiment. In FIG. 24, the solid line C1 indicates the relationship between the ink discharge amount and the image density when the inkjet recording process is performed on the workpiece not subjected to the plasma processing according to the above-described embodiment, and the broken line C2 indicates the above-described line. The relationship between the ink discharge amount and the image density when the ink jet recording process is performed on the workpiece subjected to the plasma processing according to the embodiment is shown. A one-dot broken line C3 indicates the ink reduction rate of the broken line C2 with respect to the solid line C1.

  As can be seen from the comparison between the solid line C1 and the broken line C2 in FIG. 24 and the one-dot broken line C3, by performing the plasma treatment according to the above-described embodiment on the workpiece 20 before the inkjet recording process, The ink discharge amount required to obtain the same image density is reduced by the effects such as improvement in roundness, enlargement of dots, and uniform density in the dots of pigment.

  Moreover, since the thickness of the pigment adhering to the to-be-processed object 20 becomes thin by performing the plasma process concerning the above-mentioned embodiment on the to-be-processed object 20 before an inkjet recording process, a chroma-saturation improves and color The effect of expanding the area can be obtained. Further, as a result of reducing the amount of ink, the drying energy of the ink can be reduced, so that an energy saving effect can be obtained.

  Further, in the above-described embodiment, 5 or less is given as an example of the target pH value on the surface of the workpiece 20, but this is merely an example. For example, it is considered that there is an ideal pH value that improves the wettability and permeability of each object to be processed by changing the components and types of ink and the object to be processed. Therefore, the plasma energy or the target pH value, which is the optimum condition, may be obtained in advance for each type of ink and type of object to be processed, and this may be registered in the control unit.

  In addition, you may comprise so that the discharge plasma which ionizes atmospheric gas by discharge may be given to the to-be-printed material surface before an inkjet recording process. As described above, the hydrophilicity treatment is performed on the surface of the printing material before the ink jet recording process, so that the wettability of the surface of the processing object is improved, so that the roundness of the dots formed by the ink jet recording process can be improved. It becomes possible. In addition, since the drying time of the vehicle can be shortened, the occurrence of beading can be reduced.

  In the above-described embodiment, the inkjet head for image recording and the discharge electrode for plasma processing are separately provided, but the present invention is not limited to such a configuration. For example, as in Modification 1 shown in FIGS. 25 and 26, the inkjet head 170 and the discharge electrode 110 may be mounted on the same carrier (hereinafter referred to as a carriage).

  The configuration according to Modification 1 shown in FIGS. 25 and 26 will be described in more detail. 25 and 26 illustrate, for example, the configuration from the plasma processing apparatus 100 to the ink jet head 170 in FIG. 15 and the case where the ink jet head 170 is incorporated into the plasma processing apparatus 100. 25 and 26 show a case where a set of the discharge electrode 110, the ground electrode 140, and the high-frequency high-voltage power supply 150 are mounted on a single carriage 201 for the sake of simplicity of the description. Even if a plurality of sets of discharge electrodes (for example, discharge electrodes 111 to 116), ground electrodes (for example, ground electrodes 141 to 146), and high-frequency and high-voltage power sources (for example, high-frequency and high-voltage power sources 151 to 156) are mounted on a single or a plurality of carriages 201. Good. Further, FIGS. 25 and 26 illustrate a case where two inkjet heads 170 are mounted on a single carriage 201.

  As shown in FIGS. 25 and 26, in this modification, two inkjet heads 170 and one discharge electrode 110 are mounted on a single carriage 201. The discharge electrode 110 has a roller shape and is supported so as to be rotatable with respect to the carriage 201 in, for example, the D2 direction. However, the present invention is not limited to this, and a fixed discharge electrode having a narrow gap with respect to the recording medium may be used.

  The carriage 201 is slidably provided on two guide rods 202 arranged in parallel along the scanning direction D2 of the inkjet head 170. The ink jet head 170 and the discharge electrode 110 are each fixed to the carriage 201, and as the carriage 201 moves in the scanning direction D2, itself moves in the scanning direction D2. Note that the scanning direction D2 is, for example, perpendicular to the direction of the transport path D1.

  A ground electrode (also referred to as a counter electrode) 140 is provided at a position facing the discharge electrode 110 with the dielectric 121 being an endless belt interposed therebetween. The ground electrode 140 may be provided, for example, so as to face the entire movement range of the discharge electrode 110, and has the same size as the ground electrode 140 or a size larger than the ground electrode 140. It may be provided so as to move as the carriage 201 moves.

  In the configuration described above, ink is supplied to the inkjet head 170 by an ink supply unit (not shown), and the carriage 201 is scanned on the dielectric 121 while ejecting (discharging) ink from the inkjet head 170 to be conveyed on the dielectric 121. An image is formed on the object 20 to be processed.

  Next, the operation of the printing apparatus according to the first modification will be described. Here, the operations of image formation and surface modification (plasma treatment) will be described. Other operations may be the same as in the above-described embodiment.

  The workpiece 20 supplied from a paper supply unit (not shown) is transported along the transport path D1 by the dielectric 121 (transport belt). Then, if it conveys to the discharge electrode 110 bottom, the conveyance of the to-be-processed object 20 will stop. Next, the carriage 201 moves along the scanning direction D <b> 2 while applying a high frequency / high voltage pulse voltage between the discharge electrode 110 and the ground electrode 140 by the high frequency high voltage power supply 150. Thereby, the atmospheric pressure non-equilibrium plasma generated between the electrodes moves in the scanning direction D2. As a result, the surface of the workpiece 20 on the discharge electrode 110 side is subjected to plasma treatment.

  Next, the workpiece 20 is transported to the position immediately below the inkjet head 170 by the dielectric 121 (conveyance belt) and stopped. In this state, by ejecting ink from the inkjet head 170 while scanning the carriage 201, an image corresponding to the writing width of the inkjet head 170 is formed on the workpiece 20. At the same time as the image formation, a high-frequency / high-voltage pulse voltage is applied between the discharge electrode 110 and the ground electrode 140 by the high-frequency high-voltage power supply 150, so that plasma processing is performed in a region where an image is formed next.

  Thereafter, plasma processing and image formation can be performed on the workpiece 20 by repeating the same operation.

  Further, as a second modification, a case where the scanning of the inkjet head and the scanning of the discharge electrode are performed separately will be described.

  FIG. 27 is a schematic diagram illustrating a configuration in which the inkjet head and the discharge electrode according to Modification 2 are separately provided. FIG. 28 is a top view showing the image forming area and the plasma processing area in FIG. FIG. 29 is a schematic diagram illustrating a configuration during plasma processing of the plasma processing apparatus 100 according to the second modification. FIG. 30 is a schematic diagram illustrating a configuration of the plasma processing apparatus 100 according to the second modification when a workpiece is conveyed.

  As shown in FIGS. 27 and 28, in the second modification, the plasma processing apparatus 100 and the image forming unit 40 are provided separately. The scanning direction of the discharge electrodes 111 and 112 in the plasma processing apparatus 100 is the scanning direction D2 perpendicular to the direction of the transport path D1, as in the first modification.

  In this configuration, the workpiece 20 (recording medium) wound in a roll is conveyed from the paper feed roll 31 to below the discharge electrodes 111 and 112 of the plasma processing apparatus 100 and stops. Then, in the plasma processing apparatus 100, high-frequency and high-voltage pulse voltages are supplied from the high-frequency and high-voltage power supplies 151 and 152 to the discharge electrodes 111 and 112, respectively, and the discharge electrodes 111 and 112 are moved along with the movement of the carriage (not shown). Scanning is performed in the scanning direction D2. As a result, the atmospheric pressure non-equilibrium plasma generated between the discharge electrodes 111 and 112 and the ground electrode 141 moves in the scanning direction D2, and the surface of the workpiece 20 is plasma-processed.

  However, in the case of using rotating roller type electrodes for the discharge electrodes 111 and 112 as in the second modification, the discharge electrodes 111 and 112 abut against the workpiece 20 during plasma processing as shown in FIG. ing. Therefore, the workpiece 20 cannot be transported during plasma processing. Therefore, when the workpiece 20 is transported, the contact between the discharge electrodes 111 and 112 and the workpiece 20 is released by retracting the discharge electrodes 111 and 112 upward or laterally as shown in FIG. . The positions of the discharge electrodes 111 and 112 at the time of release are the positions where the discharge electrodes 111 and 112 are moved in the width direction of the object to be processed 20 and moved outward (sideward) from the object to be processed 20. The position can be a position spaced apart upward, or a position laterally outward of the workpiece 20 and spaced apart upward. Note that, as a method of moving the discharge electrodes 111 and 112 upward, for example, a method of raising the guide rod 202 in Modification 1 by a cam mechanism (not shown) is conceivable. In addition, the configuration in which the discharge electrode is retracted when the workpiece 20 is transported can be applied to the above-described first modification.

  The workpiece 20 subjected to the plasma processing as described above is transported for the plasma processing region (below the electrode width in the transport direction D1) and stopped again, and the next region is subjected to plasma processing. By repeating this, the surface of the workpiece 20 is plasma treated. The workpiece 20 that has been plasma-treated in this manner is sequentially conveyed to the image forming unit 40.

  In the image forming unit 40, the workpiece 20 subjected to plasma processing is conveyed to the inkjet head 170 and stopped. In this state, by ejecting ink from the inkjet head 170 while moving the carriage on which the inkjet head 170 is mounted in the scanning direction D2, an image is formed on the workpiece 20 by the writing width of the inkjet head 170. The to-be-processed object 20 thus image-formed is transported for an image forming area (head width in the transport direction D1) and stopped again, and image formation for the next area is executed.

  Thereafter, plasma processing and image formation can be performed on the workpiece 20 by repeating the same operation.

  Although the invention made by the present inventor has been specifically described based on the preferred examples, the present invention is not limited to that described in the above embodiment, and various modifications can be made without departing from the scope of the invention. It goes without saying that it is possible.

DESCRIPTION OF SYMBOLS 1 Printing apparatus 10, 100, 200 Plasma processing apparatus 11, 110, 111-116 Discharge electrode 12, 121 Dielectric 122 Roller 13 Atmospheric pressure non-equilibrium plasma 14, 140, 141 Ground electrode 15, 150, 151-156 High frequency high voltage power supply DESCRIPTION OF SYMBOLS 160 Control part 170 Inkjet head 180 Pattern reading part 30 Carry-in part 31 Delivery roller 40 Image formation part 50 Drying part 60 Carry-out part 61 Take-up roller 201 Carriage 202 Guide rod

JP 2009-299796 A

Claims (20)

Plasma processing means for acidifying at least the surface of the object to be processed by plasma processing the surface of the object to be processed;
Recording means for performing ink jet recording on the surface of the workpiece after plasma processing by the plasma processing means;
Equipped with a,
The plasma processing means performs plasma processing until the viscosity of the ink applied to the surface of the object to be processed by the recording means is equal to or higher than a predetermined viscosity.
A printing apparatus characterized by that.   The printing apparatus according to claim 1, wherein the ink applied to the surface of the object to be processed by the recording unit is an ink in which a negatively charged pigment is dispersed in a liquid.   The printing apparatus according to claim 1, wherein the ink applied to the surface of the object to be processed by the recording unit is an aqueous pigment ink.   The printing apparatus according to claim 1, wherein the object to be processed is a slowly penetrating paper.   The printing apparatus according to claim 1, wherein the object to be processed is a coated paper having a coating layer on a surface thereof. The plasma processing means includes a discharge electrode, a dielectric, and a ground electrode provided on a side opposite to the discharge electrode with respect to the dielectric, and the object to be processed is the discharge electrode, the dielectric, when present during, the printing apparatus according to any one of claims 1 to 5, characterized in that a plasma treatment with an object to be processed a dielectric barrier discharge. The plasma processing unit, the printing apparatus according to any one of claims 1 to 6, characterized in that a plasma treatment using atmospheric pressure non-equilibrium plasma. The plasma processing unit, the printing apparatus according to any one of claims 1 to 7, characterized in that to increase the permeability of at least the surface of the object to be treated. Wherein the acidification, the hydrogen ion concentration of at least the surface of the object, any one of claims 1-8, wherein the recording means is characterized in that by raising in accordance with the characteristics of ink discharged The printing apparatus according to item. The plasma processing means has a plurality of discharge electrodes,
The printing apparatus includes:
Power supply means for supplying power to the plurality of discharge electrodes;
Plasma control means for controlling the amount of plasma energy applied to the surface of the object to be processed by changing the number of discharge electrodes to which power is supplied from the power supply means;
The printing apparatus according to any one of claims 1 to 5 , further comprising: The plasma processing means has a discharge electrode,
The printing apparatus includes:
Power supply means for supplying power to the discharge electrode;
Plasma control means for controlling the amount of plasma energy applied to the surface of the object to be processed by changing the voltage supplied from the power supply means to the discharge electrode;
The printing apparatus according to any one of claims 1 to 5 , further comprising: The printing apparatus includes:
Conveying means for conveying the object to be processed;
And Help plasma control means to control the plasma energy applied to the processing object surface by changing the conveying speed of the object to be processed by the conveying means,
The printing apparatus according to any one of claims 1 to 5 , further comprising: The plasma control unit, in any one of claims 10 to 12, characterized in that to control the plasma energy applied to the processing object from the plasma processing unit based on the print mode by said recording means The printing apparatus as described. The plasma control means controls the amount of plasma energy applied from the plasma processing means to the surface of the object to be processed based on the amount of ink droplets applied to the surface of the object to be processed by the recording means. The printing apparatus according to any one of claims 10 to 12 . The plasma control unit, any one of claims 10 to 12, characterized in that to control the plasma energy applied to the processing object surface from the plasma processing unit based on the recorded image by the recording means The printing apparatus according to item. The plasma control unit, the printing apparatus according the any of claims 10-12, wherein the controlling the plasma energy applied to the object surface to be treated based on the type of the object. Conveying means for conveying the object to be processed;
A carriage that moves in a direction perpendicular to the conveying direction of the workpiece;
With
The plasma processing unit, the printing apparatus according to any one of claims 1 to 16, characterized in that mounted on the carriage. The printing apparatus according to claim 17 , wherein the carriage is mounted with a head for ejecting ink among the recording means. A plasma processing apparatus that acidifies at least the surface of the object to be processed by plasma processing the surface of the object to be processed;
A recording apparatus for performing inkjet recording on the surface of the object to be processed after the plasma processing by the plasma processing apparatus;
Equipped with a,
The plasma processing apparatus performs plasma processing until the viscosity of the ink applied to the surface of the object to be processed by the recording apparatus is equal to or higher than a predetermined viscosity.
A printing system characterized by that. A manufacturing method for manufacturing a printed material on which an image is formed by inkjet recording,
A plasma treatment step of acidifying at least the surface of the workpiece by plasma-treating the workpiece surface;
A recording step of performing inkjet recording on the surface of the object to be processed after the plasma processing by the plasma processing step;
Including
The plasma treatment step performs the plasma treatment until the viscosity of the ink applied to the surface of the object to be processed by the recording step is equal to or higher than a predetermined viscosity.
A method for producing a printed matter.