Image recording method and image recording device

Abstract

To provide an image recording method and an image recording apparatus for suppressing uneven drying of an image formed on a recording medium supported by a guide surface.SOLUTION: There is provided an image recording method which comprises: a conveying step of supporting a recording medium by a guide surface to convey the recording medium together with the guide surface; an image forming step of ejecting a liquid from a liquid ejection head onto the conveyed recording medium to form an image; and a preheating step of preheating the recording medium prior to the image forming step, wherein when the temperature of the guide surface in the image forming step is defined as TG and the temperature of the recording medium is defined as TP, the drying irregularities are suppressed by the image recording method having the relationship of 0≤TG-TP≤1.2[°C].SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to an image recording method and an image recording apparatus, and more particularly to a technique for recording an image on a recording medium supported on a guide surface. [Background technology]

[0002] Inkjet recording devices are known that eject ink from an inkjet head onto a recording medium transported by a transport unit to record an image on the recording medium. A guide surface of the transport unit that supports the recording medium may be provided with a plurality of projections and recesses depending on the application.

[0003] Patent Document 1 discloses an inkjet recording device that includes a paper carrying drum that carries and transports a recording medium, paper, on its outer circumferential surface, and an ink ejection unit that ejects ink toward the paper carried on the paper carrying drum. The paper carrying drum has suction holes on its outer circumferential surface, and when the suction device is operated, a suction force is generated that attracts the paper to the suction holes. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6850429 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the inkjet recording device described in Patent Document 1 has a problem in that uneven drying occurs because the ease of heat transfer differs between the suction holes and the other parts of the outer circumferential surface of the paper carrying drum.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an image recording method and image recording apparatus that suppress uneven drying of an image formed on a recording medium supported by a guide surface. [Means for solving the problem]

[0007] One aspect of an image recording method for achieving the above object includes a conveying step of supporting a recording medium with a guide surface and conveying the recording medium together with the guide surface, an image forming step of forming an image by discharging liquid from a liquid discharge head onto the conveyed recording medium, and a preheating step of preheating the recording medium prior to the image forming step, and the temperature of the guide surface in the image forming step is set to T G , the temperature of the recording medium is T P Then, 0≦T G -T P ≦1.2° C. According to this aspect, it is possible to suppress uneven drying of an image formed on a recording medium supported by a guide surface.

[0008] 0≦T G -T P It is preferable that the relationship be ≦1.0° C. This can further suppress uneven drying.

[0009] The temperature of the recording medium is the temperature of the recording medium at the position where the liquid is applied, and the temperature of the guide surface is preferably the temperature of the guide surface at a position that is the same as the position where the liquid is applied on the recording medium. P and the temperature T of the guide surface at the same position. G By setting the above range, the liquid applied to the recording medium dries without moving, so that uneven drying of the formed image can be suppressed.

[0010] It is preferable to have a treatment liquid application step in which treatment liquid is applied to the recording medium prior to the image forming step, a switching step for switching whether or not the treatment liquid application step is performed, and a treatment liquid drying step in which the recording medium on which the treatment liquid has been applied is heated when the treatment liquid application step is performed, and which also serves as a preheating step regardless of whether or not the treatment liquid application step is performed. When the treatment liquid is applied, the treatment liquid can suppress drying unevenness, and when the treatment liquid is not applied, the pre-drying can prevent T G and T P By setting the above ranges, uneven drying can be suppressed.

[0011] The guide surface may have at least one of a convex portion and a hole portion. According to this aspect, even if the guide surface has at least one of a convex portion and a hole portion, it is possible to suppress uneven drying. The guide surface may have at least one of a large number of convex portions and holes arranged two-dimensionally.

[0012] In the conveying step, it is preferable that the recording medium is supported by using the peripheral surface of a drum rotating about an axis as a guide surface. According to this aspect, even if the peripheral surface of the drum rotating about an axis is the guide surface, it is possible to suppress uneven drying.

[0013] A liquid drying process for drying the liquid may be provided after the image forming process. According to this aspect, even if the temperature of the guide surface increases due to the influence of the liquid drying process, uneven drying can be suppressed.

[0014] It is preferable to provide a temperature measuring step for measuring the temperature of the recording medium, and in the preheating step, the recording medium is preheated based on the measured temperature. G and T P In the temperature measuring step, the temperature of the guide surface may be measured.

[0015] One aspect of an image recording apparatus for achieving the above object is a recording medium recording apparatus including a conveying mechanism that supports a recording medium on a guide surface and conveys the recording medium together with the guide surface, a liquid ejection head that ejects liquid onto the conveyed recording medium to record an image, and a preheating mechanism that preheats the recording medium before recording an image, and the temperature of the guide surface when recording an image is controlled to T G , the temperature of the recording medium is T P Then, 0≦T G -T P ≦1.2° C. According to this aspect, it is possible to suppress uneven drying of an image formed on a recording medium supported by a guide surface.

[0016] The preheating mechanism preferably includes a fan that supplies dry air to the recording medium, thereby making it possible to preheat the recording medium with the dry air.

[0017] The ink ejection device may further include a drying mechanism for drying the ejected liquid. According to this aspect, even if the temperature of the guide surface rises due to the effect of the drying mechanism, uneven drying can be suppressed. Effect of the Invention

[0018] According to the present invention, it is possible to suppress uneven drying of an image formed on a recording medium supported by a guide surface. [Brief description of the drawings]

[0019] [Figure 1] FIG. 1 is a schematic diagram showing an example of a guide surface. [Diagram 2] FIG. 2 is a cross-sectional view of the guide surface and the paper when the paper is supported by the guide surface and ink is applied. [Diagram 3] FIG. 3 is a top view of the paper. [Figure 4] FIG. 4 is a schematic diagram showing an example of a guide surface. [Diagram 5] FIG. 5 is a cross-sectional view of the guide surface and the paper when the paper is supported by the guide surface and ink is applied. [Figure 6] FIG. 6 is a top view of the paper. [Figure 7] FIG. 7 is a diagram showing the overall configuration of an inkjet recording apparatus. [Figure 8] FIG. 8 is a perspective view showing the configuration of the tip portion of the ink-jet head. [Figure 9] FIG. 9 is an enlarged view of a portion of the nozzle surface. [Figure 10] FIG. 10 is a plan view of the nozzle surface of the head module. [Figure 11] FIG. 11 is a vertical cross-sectional view showing the three-dimensional structure of the ejector. [Figure 12] FIG. 12 is a functional block diagram of a control system of the inkjet printing apparatus. [Figure 13] FIG. 13 is a graph showing the relationship between the difference between the temperature of the peripheral surface of the image forming drum and the temperature of the paper, and the visibility of drying unevenness. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0021] <Occurrence of uneven drying> Drying unevenness may occur in images recorded (image formation) by an inkjet recording device. Drying unevenness is a phenomenon in which light and dark shades appear in an image, including a phenomenon in which parts of an image appear dark, and a phenomenon in which parts of an image appear white and light due to lack of color. Drying unevenness occurs when the ink that has landed moves on the recording medium.

[0022] Conventionally, a treatment liquid is applied to a recording medium in a process prior to ejecting ink, and the ink viscosity is increased to suppress fluidity. On the other hand, if a treatment liquid is not applied, the ink is likely to move. The following describes the case where a treatment liquid is not applied.

[0023] Ink migration is likely to occur when the temperature distribution on the recording medium is uneven. When the temperature distribution is uneven, the ink dries easily where the temperature is high and the ink dries slowly where the temperature is low. In places where the ink dries easily, the ink is concentrated and the surface tension is high. Conversely, in places where the ink dries slowly, the ink is not concentrated as much and the surface tension is relatively low. This difference in surface tension causes the ink to move from areas with low surface tension to areas with high surface tension, resulting in uneven drying.

[0024] The inventors of the present application have found that the shape of the guide surface of the transport unit causes uneven temperature distribution, resulting in uneven drying. For example, if the guide surface is uneven, the unevenness causes uneven contact with the recording medium, and the degree of heat transfer to the recording medium varies depending on the location of contact.

[0025] The guide surface of the transport unit, which contacts and supports the recording medium during image formation, may have an uneven shape. FIG. 1 is a schematic diagram showing an example of a guide surface 10 that supports a recording medium. The guide surface 10 shown in FIG. 1 has a plurality of protrusions 12 and a plurality of holes 14. The protrusions 12 have a cylindrical shape with a diameter of 1.0 mm and a height of 0.1 mm. The protrusions 12 are two-dimensionally arranged at regular intervals in the vertical direction and in the horizontal direction perpendicular to the vertical direction. The holes 14 are through holes with a diameter of 1.0 mm that penetrate the guide surface 10. The holes 14 are two-dimensionally arranged at regular intervals in the vertical direction and in the horizontal direction.

[0026] Fig. 2 is a cross-sectional view of the guide surface 10 and the paper P when paper P, an example of a recording medium, is supported by the guide surface 10 and ink I is applied, showing the change in surface tension due to the penetration, drying and concentration of the ink. Fig. 3 is a top view of the paper P, showing the drying unevenness that occurs when a solid image is formed on the paper P supported by the guide surface 10. A solid image is an image with an ink coverage rate of more than 100%. Here, we consider a case where the temperature of the guide surface 10 is relatively higher than that of the recording medium.

[0027] Because the guide surface 10 is made of a material with a relatively high thermal conductivity compared to the surrounding air, heat is easily transferred to the portions of the paper P that come into contact with the protrusions 12 (positions corresponding to the protrusions 12), and the temperature of the portions of the paper P that come into contact with the protrusions 12 becomes locally high. Therefore, the temperature of the portions of the paper P that come into contact with the protrusions 12 becomes relatively high compared to the portions that do not come into contact. For this reason, as shown in FIG. 2, the ink I applied to the paper P is dried and concentrated more quickly at the portions of the paper P that come into contact with the protrusions 12, and the surface tension becomes relatively high compared to the portions that do not come into contact. Due to this difference in surface tension, the ink moves from the areas with low surface tension to the areas with high surface tension, and the ink concentrates at the positions of the paper P that come into contact with the protrusions 12.

[0028] As a result, as shown in Figure 3, drying unevenness occurs in which parts of the image have a relatively darker density. Note that Figure 3 highlights the darker parts. The darker parts are areas where ink is concentrated. In the example shown in Figure 3, the darker parts occur in correspondence with the positions of the protrusions 12, and each is a circle with a diameter of about 1.0 mm.

[0029] Furthermore, the guide surface of the transport unit may have a plurality of holes. Fig. 4 is a schematic diagram showing an example of a guide surface 20 that supports paper P. The guide surface 20 shown in Fig. 4 has a plurality of holes 22. The holes 22 are through-holes with a diameter of 0.5 mm that penetrate the guide surface 20. The holes 22 are two-dimensionally arranged at regular intervals in the vertical and horizontal directions.

[0030] Fig. 5 is a cross-sectional view of the guide surface 20 and the paper P when the paper P is supported by the guide surface 20 and ink I is applied, and shows the change in surface tension due to the penetration, drying and concentration of the ink. Fig. 6 is a top view of the paper P, and shows the uneven drying that occurs when a solid image is formed on the paper P supported by the guide surface 20. Here, too, we consider a case where the temperature of the guide surface 10 is relatively higher than the temperature of the recording medium.

[0031] Since the holes 22 (air) in the guide surface 20 have a relatively low thermal conductivity compared to the material of the guide surface 20, heat is not easily transferred to the portions of the paper P that come into contact with the air in the holes 22 (positions corresponding to the holes 22). Therefore, the temperature of the positions of the paper P that correspond to the holes 22 is relatively lower than that of the positions in contact with the guide surface 20. For this reason, as shown in FIG. 5, the ink I applied to the paper P is not dried and concentrated at the positions of the paper P that correspond to the holes 22, and the surface tension of the ink I is relatively small compared to the positions in contact with the guide surface 20. Due to this difference in surface tension, the ink moves from the areas with low surface tension to the areas with high surface tension, and the ink at the positions of the paper P that correspond to the holes 22 spreads and decreases.

[0032] As a result, as shown in Figure 6, parts of the image are whited out and the density becomes relatively light, resulting in drying unevenness. Note that Figure 6 shows the light density parts with emphasis. The relatively light density parts are parts with less ink. In the example shown in Figure 6, the relatively light density parts occur in correspondence with the positions of the holes 22, and each is a circle with a diameter of about 0.5 mm.

[0033] To address the above-mentioned issues, it is effective in improving the drying unevenness to suppress the heat conduction from the guide surface to the recording medium and thereby reduce the fluidity of the ink.

[0034] Here, in order to suppress the heat conduction, two measures can be considered: "using a guide surface made of a material with low thermal conductivity" or "minimizing the temperature difference between the guide surface and the recording medium". However, it is unrealistic to use a material with the same thermal conductivity as air for the guide surface of the transport unit. Therefore, in order to suppress the heat conduction from the guide surface to the recording medium, it can be said that a practical solution is to minimize the temperature of the guide surface and the recording medium. Specifically, this is the addition of a function to control the temperature of the guide surface or the recording medium. An image recording method and an image recording device for controlling the temperature of the recording medium will be described below.

[0035] <Inkjet recording device> [Overall structure] 7 is an overall configuration diagram showing a schematic configuration of the inkjet recording device 100. The inkjet recording device 100 is a sheet-fed printing device (an example of an "image recording device") that prints a color image on a sheet of paper P. The paper P is, for example, ordinary paper such as high-quality copy paper.

[0036] As shown in FIG. 7, the inkjet recording apparatus 100 includes a paper feed section 110, a treatment liquid application section 120, a treatment liquid drying section 130, an image forming section 140, an ink drying section 200, and an accumulation section 240.

[0037] [Paper feed section] The paper feed section 110 automatically feeds the paper sheets P one by one. The paper feed section 110 includes a paper feed device 112, a feeder board 114, and a paper feed drum 116. The paper feed device 112 takes out the paper sheets P set in a stack in a paper feed tray 112A one by one from the top, and feeds them to the feeder board 114. The feeder board 114 transfers the paper sheets P received from the paper feed device 112 to the paper feed drum 116.

[0038] The paper feed drum 116 receives the paper P fed from the feeder board 114 , and transfers the received paper P to the treatment liquid application unit 120 .

[0039] [Treatment liquid application section] The treatment liquid application section 120 applies treatment liquid to the paper P. The treatment liquid is a liquid that has the function of aggregating, insolubilizing, or thickening the color material components in the ink. The treatment liquid application section 120 includes a treatment liquid application drum 122 and a treatment liquid application device 124.

[0040] The treatment liquid application drum 122 receives the paper P from the paper feed drum 116, and transfers the received paper P to the treatment liquid drying section 130. The treatment liquid application drum 122 has a gripper 123 on its circumferential surface, and rotates while gripping the leading end of the paper P using the gripper 123, and transports the paper P by wrapping it around its circumferential surface.

[0041] The treatment liquid application device 124 applies treatment liquid to the paper P transported by the treatment liquid application drum 122 (an example of a "treatment liquid application step"). The treatment liquid is applied by using a roller.

[0042] The inkjet recording apparatus 100 has a mode in which treatment liquid is applied to the paper P and a mode in which treatment liquid is not applied to the paper P. In response to this, the treatment liquid application unit 120 is configured to be able to switch between applying and not applying treatment liquid to the paper P. When treatment liquid is not applied to the paper P, the roller that applies treatment liquid is configured to retreat from the transport path of the paper P.

[0043] [Treatment liquid drying section] The treatment liquid drying section 130 (an example of a "pre-heating mechanism") dries the paper P on which the treatment liquid has been applied. The treatment liquid drying section 130 includes a treatment liquid drying drum 132, a hot air blower 134, a hot air blower 135, and a hot air blower 136. The treatment liquid drying drum 132 receives the paper P from the treatment liquid application drum 122, and transfers the received paper P to the image forming section 140. The treatment liquid drying drum 132 includes a gripper 133 on its circumferential surface. The treatment liquid drying drum 132 rotates while gripping the leading end of the paper P using the gripper 133, and transports the paper P.

[0044] The hot air blower 134 is installed at a position facing the circumferential surface of the treatment liquid application drum 122. The hot air blower 134 is a non-contact heating means that blows air that has been heated and dried by a heater (not shown) out of an outlet (not shown) by a fan (not shown). The hot air blower 134 blows dry air (hot air) of 30 to 50° C. onto the paper P that is transported by the treatment liquid application drum 122, to dry the treatment liquid (an example of a "preheating step").

[0045] The hot air blower 135 and the hot air blower 136 are each installed inside the treatment liquid drying drum 132. The configuration of the hot air blower 135 and the hot air blower 136 is similar to that of the hot air blower 134. The hot air blower 135 and the hot air blower 136 each blow dry air (hot air) of 30 to 50° C. onto the paper P transported by the treatment liquid drying drum 132 to dry the treatment liquid. In this embodiment, the treatment liquid is dried by the hot air blower 134 installed at a position facing the circumferential surface of the treatment liquid application drum 122, and the hot air blower 135 and the hot air blower 136 installed inside the treatment liquid drying drum 132, but the number of hot air blowers and the positions at which they are installed are not particularly limited.

[0046] As described below, the treatment liquid drying section 130 blows dry air onto the paper P regardless of whether treatment liquid has been applied to the paper P. The temperature of the dry air may be changed depending on whether treatment liquid has been applied.

[0047] [Image forming section] The image forming section 140 includes an image forming drum 142, a head unit 144, and a scanner 190. The image forming drum 142 (an example of a "transport mechanism") is a cylindrical member having a rotation shaft (not shown). The image forming drum 142 receives the paper P from the treatment liquid drying drum 132, and transfers the received paper P to the ink drying section 200 by rotating around the rotation shaft (an example of a "transport process"). A peripheral surface 142A corresponding to the guide surface of the image forming drum 142 is made of SUS (Steel Use Stainless).

[0048] The image forming drum 142 has a gripper 143 on its peripheral surface 142A. The image forming drum 142 rotates while gripping the leading edge of the paper P using the gripper 143, winds the paper P around the peripheral surface 142A (one example of a "guide surface"), supports the back surface of the paper P with the peripheral surface 142A, and transports the paper P together with the peripheral surface. The image forming drum 142 has an adsorption mechanism (not shown) that adsorbs the paper P wound around the peripheral surface to the peripheral surface 142A.

[0049] Negative pressure is used for adhesion. The image forming drum 142 has many suction holes (for example, holes 14 in FIG. 1) on the peripheral surface 142A, and the paper P is attracted to the peripheral surface 142A by suction from the inside through the suction holes. Static electricity may also be used for adhesion. In this case, adhesion is achieved by charging the image forming drum 142.

[0050] The image forming drum 142 may have a number of protrusions (for example, the protrusions 12 in FIG. 1) on the peripheral surface 142A to prevent the paper P from becoming wrinkled.

[0051] Head unit 144 includes inkjet head 146C (an example of a "liquid ejection head") that ejects cyan (C) ink (an example of a "liquid"), inkjet head 146M that ejects magenta (M) ink, inkjet head 146Y that ejects yellow (Y) ink, and inkjet head 146K that ejects black (K) ink.

[0052] Inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K are disposed on a transport path of paper P using image forming drum 142 at regular intervals.

[0053] When ink is ejected from nozzles 162 (see FIG. 10) of inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K (an example of a "liquid ejection head") toward paper P transported by image forming drum 142, an image is recorded on the surface of paper P (an example of an "image forming process").

[0054] Note that, although the example shown here is a configuration using four colors of ink: cyan, magenta, yellow, and black, the combination of ink colors and the number of colors is not limited to this embodiment, and light inks, dark inks, and special color inks may be added as necessary.

[0055] Scanner 190 reads an image recorded on paper P using inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K.

[0056] [Ink drying section] The ink drying unit 200 (an example of a "drying mechanism") performs a drying process (an example of a "liquid drying step") on the paper P on which an image has been recorded by the image forming unit 140. The ink drying unit 200 includes a chain delivery 210, a paper guide 220, a hot air blower 230, and a paper detection sensor 232.

[0057] The chain delivery 210 receives the paper P from the image forming drum 142 and transfers the received paper P to the accumulation section 240. The chain delivery 210 includes a pair of endless chains 212 that travel along a specified travel path, and grips the leading end of the paper P using grippers 214 provided on the pair of chains 212 to transport the paper P along a specified transport path. A plurality of grippers 214 are provided at regular intervals along the travel direction of the chains 212.

[0058] The paper guide 220 is a member that guides the transport of the paper P using the chain delivery 210. The paper guide 220 is composed of a first paper guide 222 and a second paper guide 224.

[0059] The first paper guide 222 guides the paper P transported through the first transport section of the chain delivery 210. The second paper guide 224 guides the paper P transported through the second transport section following the first transport section.

[0060] The hot air blower 230 blows hot air onto the paper P transported by the chain delivery 210. Note that the hot air from the hot air blower 230 may heat the image forming drum 142, causing the temperature of the circumferential surface 142A to rise.

[0061] The paper detection sensor 232 detects the presence or absence of paper P. Examples of the paper detection sensor 232 include a reflective optical sensor and a transmissive optical sensor.

[0062] [Stacking section] The accumulation section 240 includes an accumulation device 242. The accumulation section 240 includes an accumulation device 242 that receives the paper P transported from the ink drying section 200 using the chain delivery 210 and accumulates the paper P. The chain delivery 210 releases the paper P at a predetermined accumulation position.

[0063] The stacking device 242 includes a stacking tray 244. The stacking device 242 receives the paper sheets P released from the chain delivery 210, and stacks the paper sheets P on the stacking tray 244 in a bundle.

[0064] <Example of inkjet head configuration> [Overall structure] The same configuration may be applied to inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K. In the following explanation, inkjet head 146C will be explained as a representative.

[0065] 8 is a perspective view showing the configuration of the tip portion of inkjet head 146C. Inkjet head 146C is a line-type liquid ejection head having a nozzle row capable of recording an image at a specified recording resolution in a single scan over the entire recording area of ​​paper P in the width direction of paper P. Such a liquid ejection head is also called a full-line type liquid ejection head or a page-wide head. The width direction of paper P is a direction perpendicular to the transport direction of paper P and parallel to the surface of paper P.

[0066] The tip portion of the inkjet head 146C has a nozzle surface 148. The nozzle surface 148 has nozzles 162 (see FIG. 10) formed therein for ejecting ink.

[0067] Furthermore, the inkjet head 146C has a structure in which a plurality of head modules 150-i are connected in a row along the longitudinal direction, where i is an integer from 1 to n. In the following description, the head module 150-i may be referred to as head module 150, with the i representing the head module number being omitted.

[0068] The head modules 150-i are attached to and integrated into a support frame 152. Each head module 150-i includes a cable 154 for electrical connection.

[0069] [Nozzle arrangement] 1 is a partially enlarged view of the nozzle surface 148. The nozzle surface 148-i of the head module 150-i is a parallelogram. Dummy plates 156 are attached to both ends of the support frame 152. The nozzle surface 148 of the inkjet head 146, together with a surface 156A of the dummy plate 156, is rectangular as a whole.

[0070] A strip-shaped nozzle arrangement section 158-i is provided in the center of the nozzle surface 148-i of the head module 150-i. The nozzle arrangement section 158-i functions as the substantial nozzle surface 148-i. Nozzles 162 are provided in the nozzle arrangement section 158-i. Note that in FIG. 9, the nozzles 162 are not shown individually, but a nozzle row 160 composed of a plurality of nozzles is shown.

[0071] Fig. 10 is a plan view of the nozzle surface 148-i of the head module 150-i. The Y direction in Fig. 10 represents the transport direction of the paper P, and the X direction represents the width direction of the paper P. A plurality of nozzles 162 are two-dimensionally arranged on the nozzle surface 148-i of the head module 150-i.

[0072] Head module 150-i has a planar shape of a parallelogram having a long side end face aligned along the V direction and inclined at an angle β with respect to the width direction of the paper P, and a short side end face aligned along the W direction and inclined at an angle α with respect to the transport direction of the paper P.

[0073] In the head module 150-i, a plurality of nozzles 162 are arranged in a matrix with the row direction along the V direction and the column direction along the W direction. The nozzles 162 may be arranged in the row direction along the width direction of the paper P and in the column direction diagonally intersecting the width direction of the paper P.

[0074] In the case of the inkjet head 146C, the projected nozzle row obtained by projecting each nozzle 162 along the X direction can be considered equivalent to a single nozzle row in which the nozzles 162 are lined up at approximately equal intervals at a nozzle density that achieves the maximum recording resolution in the X direction. Approximately equal intervals means that the nozzles are substantially equal in intervals as droplet ejection points that can be recorded by the inkjet recording apparatus 100. For example, the concept of equal intervals also includes cases in which the intervals are slightly different in consideration of at least one of manufacturing errors and the movement of droplets on the paper P due to landing interference.

[0075] There are no limitations on the arrangement of the nozzles of the inkjet head 146, and various nozzle arrangements can be adopted. For example, instead of a two-dimensional matrix arrangement, a linear arrangement in one row, a V-shaped nozzle arrangement, and a zigzag arrangement such as a W-shape in which V-shaped arrangements are repeated are also possible.

[0076] [Ejector Configuration] 11 is a vertical cross-sectional view showing the three-dimensional structure of the ejector 164. The ejector 164 includes a nozzle 162, a pressure chamber 166 communicating with the nozzle 162, and a piezoelectric element 168. The nozzle 162 communicates with the pressure chamber 166 via a nozzle flow path 170. The pressure chamber 166 communicates with a supply-side common branch flow path 174 via an individual supply path 172.

[0077] The diaphragm 176 that constitutes the top surface of the pressure chamber 166 includes a conductive layer (not shown) that functions as a common electrode that corresponds to the lower electrode of the piezoelectric element 168. The pressure chamber 166, the walls of the other flow path parts, the diaphragm 176, etc. can be made of silicon.

[0078] The material of the diaphragm 176 is not limited to silicon, and it may be made of a non-conductive material such as resin. The diaphragm 176 itself may be made of a metal material such as stainless steel, and may serve as a common electrode.

[0079] A piezoelectric unimorph actuator is formed by stacking piezoelectric elements 168 on a vibration plate 176. A drive voltage is applied to an individual electrode 178, which is the upper electrode of the piezoelectric element 168, to deform the piezoelectric body 180, which deflects the vibration plate 176 and changes the volume of the pressure chamber 166. The pressure change caused by the change in volume of the pressure chamber 166 acts on the ink, causing the ink to be ejected from the nozzle 162.

[0080] When the piezoelectric element 168 returns to its original state after ink is ejected, new ink is filled into the pressure chamber 166 from the supply-side common branch channel 174 through the individual supply channel 172. The operation of filling the pressure chamber 166 with ink is called refilling.

[0081] The planar shape of the pressure chamber 166 is not particularly limited, and may be various shapes such as a rectangle or other polygon, a circle, an ellipse, etc. A cover plate 182 is provided above the individual electrode 178. The cover plate 182 is a member that maintains a movable space 184 for the piezoelectric element 168 and seals the periphery of the piezoelectric element 168.

[0082] A supply-side ink chamber (not shown) and a recovery-side ink chamber (not shown) are formed above the cover plate 182. The supply-side ink chamber is connected to a supply-side common main flow channel (not shown) via a communication passage (not shown). The recovery-side ink chamber is connected to a recovery-side common main flow channel (not shown) via a communication passage (not shown).

[0083] <Control system configuration> 12 is a functional block diagram of a control system of the inkjet recording apparatus 100. The inkjet recording apparatus 100 includes a system controller 250. The system controller 250 is an overall control unit that comprehensively controls each unit of the inkjet recording apparatus 100. The system controller 250 is a calculation unit that performs various calculation processes. The system controller 250 is a memory controller that controls reading and writing of data in memory.

[0084] [Communications Department] The inkjet recording apparatus 100 includes a communication unit 252. The communication unit 252 transmits and receives data to and from a host computer 254 connected via a communication interface (not shown).

[0085] [Image memory] The inkjet recording apparatus 100 includes an image memory 256. The image memory 256 functions as a temporary storage unit for various data including image data. Data is read from and written to the image memory 256 via a system controller 250. Image data received from a host computer 254 via a communication unit 252 is stored in the image memory 256.

[0086] [Transport control unit] The inkjet recording apparatus 100 includes a transport control unit 258. The transport control unit 258 controls the operation of the transport unit 109. The transport unit 109 includes the paper feed drum 116, the treatment liquid application drum 122, the image forming drum 142, and the chain delivery 210 shown in FIG.

[0087] [Paper feed control unit] The inkjet recording apparatus 100 includes a paper feed control unit 260. The paper feed control unit 260 operates the paper feed unit 110 in response to a command from a system controller 250.

[0088] [Treatment liquid application control unit] The inkjet recording apparatus 100 includes a treatment liquid application control unit 262. The treatment liquid application control unit 262 controls the operation of the treatment liquid application unit 120 in response to a command from the system controller 250.

[0089] The treatment liquid application control unit 262 controls switching between applying and not applying treatment liquid to the paper P by the treatment liquid application unit 120 according to the set mode (an example of a "switching step"). Switching between a mode in which treatment liquid is applied to the paper P and a mode in which treatment liquid is not applied to the paper P may be performed by a user input via the operation unit 272, or may be performed by automatically determining the need for treatment liquid by, for example, determining the type of paper P using a sensor (not shown).

[0090] [Treatment Liquid Drying Control Unit] The inkjet recording apparatus 100 includes a treatment liquid drying control unit 264. The treatment liquid drying control unit 264 controls the operation of the treatment liquid drying unit 130 in response to a command from the system controller 250.

[0091] [Drawing control section] The inkjet recording apparatus 100 includes an image formation control unit 266. The image formation control unit 266 controls the operation of the image forming unit 140 in response to a command from the system controller 250.

[0092] The image forming control unit 266 includes an image processing unit (not shown). The image processing unit forms dot data from input image data. The image processing unit includes a color separation processing unit (not shown), a color conversion processing unit (not shown), a correction processing unit (not shown), and a halftone processing unit (not shown).

[0093] The color separation processing unit performs color separation processing on the input image data. For example, if the input image data is expressed in RGB (Red Green Blue), the input image data is separated into data for each of the colors R, G, and B.

[0094] The color conversion processing unit converts the image data for each color separated into R, G, and B into C, M, Y, and K corresponding to the ink colors.

[0095] The correction processing unit performs correction processing on the image data for each color converted into C, M, Y, and K. Examples of the correction processing include gamma correction processing, uneven density correction processing, and abnormal recording element correction processing.

[0096] The halftone processing unit converts image data expressed in multiple gradations, such as 0 to 255, into dot data expressed in binary or multiple values ​​of 3 or more values ​​that are less than the number of gradations of the input image data. The halftone processing unit applies a predetermined halftone processing rule. Examples of halftone processing rules include the dither method and the error diffusion method.

[0097] The image formation control unit 266 includes a waveform generating unit (not shown), a waveform storage unit (not shown), and a drive circuit (not shown). The waveform generating unit generates a waveform of the drive voltage. The waveform storage unit stores the waveform of the drive voltage.

[0098] The drive circuit generates a drive voltage having a drive waveform corresponding to the dot data. The drive circuit supplies the drive voltage to inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K shown in FIG.

[0099] That is, the ejection timing and ink ejection amount for each pixel position are determined based on the dot data generated through processing by the image processing unit. A drive voltage according to the ejection timing and ink ejection amount for each pixel position, and a control signal for determining the ejection timing for each pixel are generated. The drive voltage and control signal are supplied to inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K, and dots are formed on paper P by the ink ejected from inkjet head 146C, inkjet head 146M, inkjet head 146Y, and inkjet head 146K.

[0100] [Ink drying control unit] The inkjet recording apparatus 100 includes an ink drying control unit 268. The ink drying control unit 268 controls the operation of the ink drying unit 200 in response to a command from the system controller 250.

[0101] [Integration control section] The inkjet recording apparatus 100 includes a stacking control unit 270. The stacking control unit 270 controls the operation of the stacking unit 240 in response to a command from the system controller 250. The operation of the stacking unit 240 may include the opening and closing operation of the gripper 214 when stacking the paper P on which an image has been formed in the stacking device 242 shown in FIG.

[0102] [Operation unit] The inkjet recording apparatus 100 includes an operation unit 272. The operation unit 272 includes operation members such as an operation button, a keyboard, and a touch panel. The operation unit 272 may include a plurality of types of operation members. Information input using the operation unit 272 is transmitted to the system controller 250. The system controller 250 generates command signals for executing various processes according to the information transmitted from the operation unit 272. The system controller 250 transmits the command signals to a processing unit that performs various processes.

[0103] [Display] The inkjet recording apparatus 100 includes a display unit 274. The display unit 274 includes a display device (not shown), such as a liquid crystal panel, and a display driver (not shown). The display unit 274 displays various information, such as various setting information of the apparatus and abnormality information, on the display device in response to a command from the system controller 250. The display unit 274 may be a touch panel type display device and may also function as the operation unit 272.

[0104] [Parameter storage unit] The inkjet recording apparatus 100 includes a parameter storage unit 276. The parameter storage unit 276 stores various parameters used in the inkjet recording apparatus 100. The various parameters stored in the parameter storage unit 276 are read out using a system controller 250. The various parameters are set in each unit of the apparatus using the system controller 250.

[0105] [Program storage section] Inkjet recording apparatus 100 includes a program storage unit 278. Programs used by each unit of inkjet recording apparatus 100 are stored in program storage unit 278. Various programs stored in program storage unit 278 are read out via system controller 250 and executed in each unit of the apparatus.

[0106] [Sensor] The inkjet recording apparatus 100 includes a sensor 280. The sensor 280 includes at least an optical sensor and a pressure sensor. The sensor 280 may include various sensors such as a temperature sensor and a flow rate sensor.

[0107] [Hardware configuration of various control units] Processors are applied to the various control units shown in Fig. 12. The hardware structure of the processor is various processors as shown below. The various processors include a CPU (Central Processing Unit), which is a general-purpose processor that executes software (programs) and acts as various functional units, a GPU (Graphics Processing Unit), which is a processor specialized for image processing, a PLD (Programmable Logic Device), which is a processor whose circuit configuration can be changed after manufacture such as an FPGA (Field Programmable Gate Array), and a dedicated electric circuit, which is a processor having a circuit configuration designed specifically for executing specific processing such as an ASIC (Application Specific Integrated Circuit).

[0108] A processing unit may be configured with one of these various processors, or may be configured with two or more processors of the same or different types (for example, multiple FPGAs, or a combination of a CPU and an FPGA, or a combination of a CPU and a GPU). Also, multiple functional units may be configured with one processor. As an example of configuring multiple functional units with one processor, first, as represented by a computer such as a client or a server, there is a form in which one processor is configured with a combination of one or more CPUs and software, and this processor acts as multiple functional units. Second, as represented by a SoC (System On Chip), there is a form in which a processor is used that realizes the functions of the entire system including multiple functional units with one IC (Integrated Circuit) chip. In this way, the various functional units are configured using one or more of the above various processors as a hardware structure.

[0109] Furthermore, the hardware structure of these various processors is, more specifically, an electric circuit that combines circuit elements such as semiconductor elements.

[0110] The processor executes instructions stored in a memory (not shown). The memory stores instructions to be executed by the processor. The memory includes a RAM (Random Access Memory) and a ROM (Read Only Memory), not shown. The processor uses the RAM as a working area, executes software using various programs and parameters, including a survey support program, stored in the ROM, and executes various processes by using parameters stored in the ROM, etc.

[0111] <Action of the Inkjet Recording Apparatus> The inkjet recording device 100 performs an image recording method in which the paper P is heated by the treatment liquid drying section 130, the preheated paper P is supported by the peripheral surface 142A of the image forming drum 142 and transported integrally with the peripheral surface 142A, and an image is formed by ejecting ink from the inkjet heads 146C, 146M, 146Y, and 146K onto the paper P transported by the image forming drum 142. According to this image recording method, since the paper P is preheated by the treatment liquid drying section 130, the temperature difference between the peripheral surface 142A of the image forming drum 142 and the paper P when an image is formed can be relatively small. Therefore, the heat conduction from the peripheral surface 142A to the paper P can be suppressed to reduce the fluidity of the ink, and therefore uneven drying can be suppressed.

[0112] Furthermore, the inkjet recording apparatus 100 implements an image recording method in which the presence or absence of a treatment liquid application process is switched in the treatment liquid drying control section 264. When the treatment liquid application process is included, the treatment liquid is applied to the paper P in the treatment liquid application section 120 prior to the image forming process, and the paper P coated with the treatment liquid is heated in the treatment liquid drying section 130, which also serves as preheating (an example of a "treatment liquid drying process"). When the treatment liquid application process is not included, the treatment liquid drying control section 264 preheats the paper P in the treatment liquid drying section 130 (an example of a "preheating process").

[0113] According to this image recording method, when the treatment liquid is applied, the treatment liquid can suppress drying unevenness. Furthermore, when the treatment liquid is not applied, the treatment liquid drying unit 130 pre-dries the paper P, thereby suppressing heat conduction from the peripheral surface 142A to the paper P, reducing the fluidity of the ink and suppressing drying unevenness. Furthermore, while adding a new temperature adjustment mechanism for pre-heating is not cost-effective, according to this image recording method, the treatment liquid drying unit 130 also serves as a pre-heating mechanism, thereby reducing costs.

[0114] <Relationship between temperature difference on guide surface and paper and visibility of drying unevenness> It has been confirmed that uneven drying can be reduced by preheating the paper P and relatively reducing the temperature difference between the circumferential surface 142A of the image forming drum 142 and the paper P.

[0115] FIG. 13 shows the temperature T G and the temperature T of the paper P P Temperature difference (T G -T P 13 is a graph showing the relationship between the temperature difference (T G -T P ), and the vertical axis indicates the results of a sensory evaluation of the visibility level of drying unevenness in a solid image formed at each temperature difference.

[0116] The temperature T of the peripheral surface 142A of the image forming drum 142 G , and the temperature T of the paper P P was measured at a position immediately before ink droplets were ejected by the inkjet head 146C, the inkjet head 146M, the inkjet head 146Y, and the inkjet head 146K. G The temperature of the ink was 26 to 32°C.

[0117] The results of the sensory evaluation of the visibility level of drying unevenness were classified as follows, with Class A or higher being the pass mark.

[0118] A ++ : Very good (no visible drying marks) A + :A ++ Worse than A and better than B A: Good (drying unevenness is barely visible) B + :Worse than A and better than B B: Poor (drying unevenness is slightly visible) C + :Worse than B and better than C C: Very bad (uneven drying is visible) The visibility of drying unevenness in solid images formed at each temperature difference was plotted in the graph of Fig. 13. The straight line shown in Fig. 13 is an approximation straight line derived from each plot point.

[0119] As shown in FIG. 13, in order to make the visibility of the drying unevenness of a solid image above the acceptable line, the temperature T G and the temperature T of the paper P P And, 0≦T G -T P ≦1.2[℃], and 0≦T G -T P It is clear that it is more preferable for the relationship to be ≦1.0° C.

[0120] The amount of heat required in the treatment liquid drying section 130 varies depending on the type of paper P, such as its material and thickness. It is therefore preferable to provide a reference table linking the type of paper P with the amount of heat (e.g., the temperature of the drying air) and to control the treatment liquid drying section 130 to an amount of heat according to the type of paper P. The amount of heat required also varies depending on whether or not treatment liquid is applied. It is therefore preferable to provide a reference table linking the amount of heat with whether or not treatment liquid is applied and to control the treatment liquid drying section 130 to an amount of heat according to whether or not treatment liquid is applied.

[0121] <Other> So far, we have described the case where the temperature of the peripheral surface 142A of the image forming drum 142 is higher than the temperature of the paper P. On the other hand, when the temperature of the paper P is higher than the temperature of the peripheral surface 142A of the image forming drum 142, in order to make the visibility of the drying unevenness of a solid image equal to or higher than the pass line, based on the findings so far, the following condition must be satisfied: −1.2≦T G -T P ≦0[℃], and -1.0≦T G -T P ≦0[° C.]. Integrating these factors, in order to make the visibility of drying unevenness of a solid image equal to or higher than the acceptable line, G -T PIt is preferable that the relationship of |≦1.2[° C.] is satisfied, and |T G -T P It is more preferable that the relationship be |≦1.0° C.

[0122] A temperature sensor (not shown) that measures the temperature of the paper P transported by the image forming drum may be provided, and the treatment liquid drying control unit 264 may measure the temperature of the paper P by the temperature sensor (an example of a "temperature measurement step") and feedback-control the treatment liquid drying unit 130 based on the measurement result of the temperature sensor. In this case, the treatment liquid drying control unit 264 may set the temperature of the drying air in accordance with the measurement result of the temperature sensor. A temperature sensor (not shown) that measures the temperature of the circumferential surface 142A of the image forming drum 142 may be provided, and the treatment liquid drying control unit 264 may measure the temperature of the circumferential surface 142A by the temperature sensor, and feedback-control the treatment liquid drying unit 130 based on the measurement result of the temperature sensor.

[0123] In this embodiment, the guide surface supporting the paper P is the peripheral surface 142A of the image forming drum 142, which is a curved surface, but the guide surface is not limited to a curved surface and may be a flat surface, and a flat guide surface may have at least one of a large number of protrusions and a large number of holes.

[0124] In this embodiment, the recording medium is a sheet of paper P, but the recording medium is not limited to paper, and various sheet bodies such as resin sheets, films, and other sheets of any material and shape can be used.

[0125] In this embodiment, the recording medium is preheated to 0≦T G -T P ≦1.2[℃], but by adjusting the temperature of the guide surface (for example by cooling), G -T P The relationship may be ≦1.2°C.

[0126] The technical scope of the present invention is not limited to the scope described in the above embodiments. The configurations and the like in each embodiment can be appropriately combined with each other without departing from the spirit of the present invention. [Explanation of symbols]

[0127] 10...Guide surface 12…Convex part 14...Hole 20...Guide surface 22...Hole 100...Inkjet recording device 109...Transportation section 110…Paper feed section 112...Paper feeder 112A…Paper feed tray 114…Feeder board 116...Paper feed drum 120... Processing liquid application section 122... Processing liquid application drum 123...Gripper 124... Processing liquid application device 130... Processing liquid drying section 132... Processing liquid drying drum 133...Gripper 134…Hot air blower 135…Hot air blower 136…Hot air blower 140...Image forming unit 142...Image forming drum 142A…Surrounding surface 143...Gripper 144…Head unit 146...Inkjet head 146C...Inkjet head 146K...Inkjet head 146M…Inkjet head 146Y...Inkjet head 148…Nozzle surface 148-i…Nozzle surface 150…Head module 150-i…Head module 152…Support frame 154…Cable 156…Dummy plate 156A…Surface 158-i…Nozzle arrangement section 160…Nozzle row 162…Nozzle 164…Ejector 166…Pressure chamber 168...Piezoelectric element 170…Nozzle flow path 172…Individual supply route 174…Supply side common tributary flow path 176...Diaphragm 178...Individual electrode 180...Piezoelectric body 182…Cover plate 184…Movable space 190…Scanner 200…Ink drying section 210…Chain delivery 212…Chain 214...Gripper 220...Paper guide 222…First paper guide 224…Second paper guide 230…Hot air blower 232...Paper detection sensor 240…Accumulation section 242...Accumulation device 244…Stacking tray 250…System controller 252…Communications Department 254...Host computer 256…Image memory 258...Transport control unit 260...Paper feed control unit 262... Processing liquid application control unit 264... Processing liquid drying control unit 266...Image formation control unit 268...Ink drying control unit 270...Integration control section 272...Operation unit 274...Display section 276...Parameter storage section 278…Program storage section 280…Sensor

Claims

1. a conveying step of supporting the recording medium with a guide surface and conveying the recording medium integrally with the guide surface; an image forming step of forming an image by ejecting liquid from a liquid ejection head onto the conveyed recording medium; a preheating step of preheating the recording medium before the image forming step; Equipped with The temperature of the guide surface in the image forming process is T Ｇ , the temperature of the recording medium is T Ｐ Then, 0≦T Ｇ -T Ｐ ≦1.2[℃] The image recording method has the following relationship:

2. 0≦T Ｇ -T Ｐ ≦1.0[℃] 2. The image recording method according to claim 1, wherein the relationship is:

3. the temperature of the recording medium is the temperature of the recording medium at a position where the liquid is applied, 3. The image recording method according to claim 1, wherein the temperature of the guide surface is the temperature of the guide surface at a position on the recording medium that is the same as the position where the liquid is applied.

4. a treatment liquid application step of applying a treatment liquid to the recording medium prior to the image forming step; A switching step of switching between the presence and absence of the treatment liquid application step; a treatment liquid drying step of heating the recording medium on which the treatment liquid has been applied when the treatment liquid application step has been performed, the treatment liquid drying step also serving as the preheating step regardless of whether the treatment liquid application step has been performed or not; The image recording method according to claim 1 , further comprising:

5. The image recording method according to claim 1 , wherein the guide surface has at least one of a convex portion and a hole portion.

6. The image recording method according to claim 1 , wherein the conveying step supports the recording medium using a peripheral surface of a drum that rotates about an axis as the guide surface.

7. The image recording method according to claim 1 , further comprising a liquid drying step of drying the liquid after the image forming step.

8. a temperature measuring step of measuring a temperature of the recording medium, The image recording method according to claim 1 , wherein the preheating step preheats the recording medium based on the measured temperature.

9. a conveying mechanism that supports the recording medium with a guide surface and conveys the recording medium integrally with the guide surface; a liquid ejection head that ejects liquid onto the transported recording medium to record an image; a preheating mechanism for preheating the recording medium before recording the image; Equipped with The temperature of the guide surface when recording the image is T Ｇ , the temperature of the recording medium is T Ｐ Then, 0≦T Ｇ -T Ｐ ≦1.2[℃] An image recording device having the above relationship.

10. The image recording apparatus according to claim 9 , wherein the preheating mechanism includes a fan that supplies dry air to the recording medium.

11. The image recording apparatus according to claim 9 or 10, further comprising a drying mechanism for drying the ejected liquid.

Images