Printing device and printing method

Abstract

The present invention provides a printing device and a printing method for reducing the color difference between the start of printing and after saturation. In step (S115), the printer control unit (200) uses the average printing duty cycle as input to refer to a table to obtain the saturation temperature and the drum preheating temperature. In this embodiment, since the saturation temperature and the drum preheating temperature relative to the printing duty cycle are stored as a table, the printer control unit (200) uses the average printing duty cycle as input to refer to the table to obtain the saturation temperature and the drum preheating temperature. In step (S120), the printer control unit (200) checks the current drum temperature based on the measurement result of the temperature sensor (TS). Then, in step (S125), the drum is heated or cooled until the temperature reaches the saturation temperature or the drum preheating temperature, whichever is closer to the difference between the current drum temperature.

Description

Technical Field

[0001] The present invention relates to a technology for recording an image by curing photocurable ink ejected onto a recording medium by light irradiation. Background Art

[0002] When a recording medium is supported by a support and a photocurable ink ejected onto the recording medium is cured by light irradiation to record an image, the temperature of the recording medium and the support rises due to reaction heat.

[0003] The greater the temperature change of the recording medium or support drum, the greater the color difference. This is because when the support or recording medium temperature is high, the ink is more fluid, so it tends to wet and spread, and the color becomes darker. On the other hand, when the support or recording medium temperature is low, the ink is less fluid, so it is less likely to wet and spread, and the color becomes lighter.

[0004] Therefore, Patent Document 1 states that before starting printing, the temperature of the conveying surface of the conveying drum is set to a specified set temperature (45°C) by a heating unit or a cooling unit before starting printing, and the surface temperature of the recording medium is obtained during printing. When the temperature becomes higher than the upper limit temperature (50°C), printing is stopped and the conveying drum is cooled.

[0005] Patent Document 1: International Patent Publication No. WO2016 / 182037

[0006] The inventors of this application conducted intensive experiments and found that the temperature changes of the recording medium and support (transport drum) caused by photocurable ink vary depending on the amount of ink ejected for each printed image (hereinafter referred to as the print duty cycle). The temperature difference between images with a low print duty cycle and images with a high print duty cycle is greater than 10°C. Furthermore, it was found that if the print duty cycle is constant, the temperature of the recording medium and support stabilizes at a constant saturation temperature corresponding to the print duty cycle.

[0007] Therefore, as described in Patent Document 1, even if printing is started after the temperature of the transport drum's transport surface is set to a predetermined set temperature (45°C) by a heating unit or cooling unit, the saturation temperature of the recording medium and support differs depending on the print duty cycle. As a result, color differences occur between the start of printing and after saturation, depending on the print duty cycle. Summary of the Invention

[0008] The present invention reduces the color difference between the beginning of printing and after saturation.

[0009] The present invention comprises: a conveying unit; a recording medium conveyed by the conveying unit; a supporting unit for supporting the recording medium conveyed by the conveying unit; a discharge unit located at a position opposite to the supporting unit and discharging photocurable ink onto the recording medium supported by the supporting unit to form an image; a light irradiation unit for irradiating the photocurable ink discharged onto the recording medium with light on a downstream side of a conveying path of the recording medium relative to the discharge unit to cure the photocurable ink; a temperature adjustment unit capable of at least one of cooling and heating the supporting unit; a storage unit for storing at least one of a relationship between a printing duty cycle and a preheating temperature and a relational expression representing the relationship between the printing duty cycle and the preheating temperature; and a control unit for acquiring the printing duty cycle of the printed image and adjusting the temperature adjustment unit based on the acquired printing duty cycle and the relationship or the relational expression stored in the storage unit so that the recording medium or the supporting unit reaches the preheating temperature.

[0010] In the above configuration, the storage unit stores at least one of: 1. a relationship between the printing duty cycle and the preheating temperature; and 2. a relational expression representing the relationship between the printing duty cycle and the preheating temperature. Furthermore, the control unit acquires the printing duty cycle of the printed image and adjusts the temperature adjustment unit based on the acquired printing duty cycle and the relationship or relational expression stored in the storage unit so that the support portion reaches the preheating temperature.

[0011] Thus, according to the present invention, the printing duty cycle of the image to be printed is obtained before printing, and printing is started after the preheating temperature reaches the set temperature corresponding to the obtained printing duty cycle. Thus, even at the start of printing and after saturation, no color difference corresponding to the printing duty cycle will occur. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 This is a front view showing an overview of the hardware configuration of the printer.

[0013] Figure 2 This is a block diagram schematically showing the electrical configuration for controlling a printer.

[0014] Figure 3 Graph showing temperature changes during multiple printing operations with different printing duty cycles.

[0015] Figure 4 Graph showing the relationship between the saturation temperature and the preheating temperature for three-stage jobs with different printing duty ratios.

[0016] Figure 5 This is a flowchart of the printer control unit.

[0017] Figure 6 This is a flowchart of the printer control unit.

[0018] Description of Reference Numerals

[0019] 1: Printer; 2: Feeding unit; 3: Processing unit; 4: Take-up unit; 10: Main computer; 20: Feeding shaft; 21: Driven roller; 21, 33, 34: Driven rollers; 30: Platen drum; 31: Front drive roller; 32: Rear drive roller; 40: Take-up shaft; 51: Recording head; 52: Recording head; 61: UV lamp; 62: UV lamp; 63: UV lamp; 100: Main control unit; 120: Driver; 122: Media; 124: Program; 130: Monitor; 140: Operation unit; F1, F2: Fans; H1, H2: Heaters; 200: Printer control unit; MM: Motor; SS: Sensor; TS: Temperature sensor; MR: Memory. DETAILED DESCRIPTION

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

[0021] Figure 1 This is a front view showing an overview of the hardware configuration of a printer to which the present invention can be applied. Figure 1 As shown, in the printer 1, a sheet S, with its ends wound in a roll-like manner around a feed shaft 20 and a take-up shaft 40, is suspended between the feed shaft 20 and the take-up shaft 40. The sheet S is transported along this suspended path from the feed shaft 20 to the take-up shaft 40. Then, in the printer 1, an image is recorded on the sheet S being transported along this transport path. In short, the printer 1 includes a feed unit 2 that feeds the sheet S from the feed shaft 20; a processing unit 3 that records an image on the sheet S fed from the feed unit 2; and a take-up unit 4 that takes the sheet S, on which the image has been recorded by the processing unit 3, and winds it onto the take-up shaft 40. It should be noted that in the following description, the side of the sheet S on which the image is recorded is referred to as the front side, and the opposite side is referred to as the back side.

[0022] The delivery unit 2 includes a delivery shaft 20 around which the end of the sheet S is wound, and a driven roller 21 around which the sheet S is pulled out from the delivery shaft 20. The delivery shaft 20 is wound around the end of the sheet S to support it with the surface of the sheet S facing outward. Figure 1 The sheet S wound around the delivery shaft 20 is delivered to the processing unit 3 via the driven roller 21 by the clockwise rotation of the delivery shaft 20 .

[0023] The processing section 3 supports the sheet S fed from the delivery section 2 via the platen drum 30 while appropriately processing the sheet S using the functional sections 51, 52, 61, 62, and 63 arranged along the outer circumference of the platen drum 30 to record an image on the sheet S. In the processing section 3, a front drive roller 31 and a rear drive roller 32 are provided on either side of the platen drum 30. The sheet S, which is fed from the front drive roller 31 to the rear drive roller 32, is supported by the platen drum 30 to receive image recording.

[0024] The platen drum 30 is a rotatably supported cylindrical drum. It winds up the sheet S being conveyed from the front drive roller 31 to the rear drive roller 32 from its back side. Specifically, the sheet S being conveyed from the front drive roller 31 to the rear drive roller 32 is supported by the outer circumference of the platen drum 30. Thus, the front and rear drive rollers 31, 32, and the intermediate driven rollers 21, 33, 34, and 41 function as a conveying unit for conveying recording media. Furthermore, the platen drum 30 functions as a support unit for supporting the recording medium being conveyed by the conveying unit.

[0025] Furthermore, the processing unit 3 is equipped with multiple recording heads 51 corresponding to different colors to record a color image on the surface of the sheet S supported by the platen drum 30. Specifically, four recording heads 51 corresponding to yellow, cyan, magenta, and black are arranged in this color order in the conveyance direction Ds. Each recording head 51 faces the surface of the sheet S wound around the platen drum 30 with a predetermined gap therebetween and ejects ink of the corresponding color using an inkjet method. Each recording head 51 ejects ink onto the sheet S being conveyed in the conveyance direction Ds, thereby forming a color image on the surface of the sheet S.

[0026] In this manner, each recording head 51 corresponds to a discharge unit that is located at a position facing the support unit and discharges photocurable ink onto a recording medium supported by the support unit to form an image.

[0027] The ink used is UV (ultraviolet) ink (photocurable ink) that is cured by irradiation with ultraviolet rays (light). Therefore, in the processing unit 3, UV lamps 61 and 62 (light irradiation units) are provided to cure the ink so as to fix it on the sheet S. It should be noted that the ink curing is performed in two stages: temporary curing and formal curing. A UV lamp 61 for temporary curing is arranged between each of the multiple recording heads 51. That is, the UV lamp 61 is a lamp that cures the ink (temporary curing) to the extent that the shape of the ink does not collapse by irradiating weak ultraviolet rays, rather than a lamp that completely cures the ink. On the other hand, a UV lamp 62 for formal curing is provided on the downstream side of the multiple recording heads 51 in the conveying direction Ds. That is, the UV lamp 62 is a lamp that completely cures the ink (formally cures) by irradiating stronger ultraviolet rays than the UV lamp 61. In this way, by performing temporary curing and formal curing, the color image formed by the multiple recording heads 51 can be fixed on the surface of the sheet S.

[0028] Thus, the UV lamps 61 and 62 correspond to light irradiation units that irradiate and cure the photocurable ink ejected onto the recording medium on the downstream side of the transport path of the recording medium relative to the ejection unit.

[0029] It should be noted that, in this embodiment, temporary curing and main curing are performed, but curing does not necessarily need to be performed in two stages.

[0030] Generally, when photocurable ink is irradiated with ultraviolet light, reaction heat is generated. Consequently, the sheet S (recording medium) where the ink is attached generates heat, which is then transferred to the platen drum 30, raising the temperature of the platen drum 30. While strictly speaking, a temperature difference exists between the sheet and the platen drum 30, this embodiment allows the processing to proceed while maintaining a substantially uniform temperature between the two.

[0031] As described above, in the present invention, regarding the temperature of the recording medium or the supporting portion, it is considered that there is no particular distinction between the two.

[0032] A plurality of fans F1 and F2 are provided as cooling means to suppress the temperature rise caused by the heat generation and to cool the platen drum 30. Each fan F1 and F2 can be turned on and off individually, and the cooling intensity can be changed in stages by the number of fans in operation.

[0033] On the other hand, a plurality of heaters H1 and H2 are provided as heating means for heating the platen drum 30 to a predetermined print start temperature before printing starts. Each heater H1 and H2 can be turned on and off individually, and the heating intensity can be changed in stages by the number of heaters H1 and H2.

[0034] Thus, each fan F1, F2 and heater H1, H2 acts as a temperature adjustment unit capable of cooling or heating the support portion. In this embodiment, both cooling and heating are achieved, but it is also possible to achieve only cooling or only heating. Furthermore, while the intensity is varied by turning the heaters and fans on and off individually, it is also possible to adjust the intensity by dividing the current into multiple steps or by continuously varying the current without steps.

[0035] In addition, in this embodiment, multiple heaters H1 and H2 are provided as heating means for heating the platen drum 30 to a predetermined print start temperature before printing begins. However, the multiple heaters H1 and H2 may not be provided. In this case, in order to heat the platen drum 30 to the predetermined print start temperature before printing begins, a process may be performed by continuously ejecting photocurable ink onto the recording medium and irradiating the ink with ultraviolet light from the UV lamp 61 to cure the ink and generate reaction heat until the temperature of the platen drum 30 reaches the predetermined print start temperature.

[0036] A recording head 52 is positioned downstream of the UV lamp 62 in the conveying direction Ds. This recording head 52 is positioned across a predetermined gap from the surface of the sheet S wound around the platen drum 30 and ejects transparent UV ink onto the surface of the sheet S using an inkjet method. In other words, transparent ink is ejected for the color image formed by the four color recording heads 51. Furthermore, a UV lamp 63 is positioned downstream of the recording head 52 in the conveying direction Ds. This UV lamp 63 completely cures (formally cures) the transparent ink ejected from the recording head 52 by irradiating it with strong ultraviolet light. This allows the transparent ink to be fixed to the surface of the sheet S.

[0037] As described above, the sheet S is supported by being wound around the platen drum 30. To cure the UV ink that has dripped onto the surface of the sheet S, the sheet S, which is thus wound around the winding portion Ra of the outer peripheral surface of the platen drum 30, is irradiated with ultraviolet light. Furthermore, in the processing unit 3, to suppress the temperature rise of the UV ink during this process, fans F1 and F2 cool the platen drum 30 so that the heat generated by the UV ink is dissipated toward the platen drum 30. Furthermore, when the temperature of the platen drum 30 drops below its saturation temperature at the start of printing, heaters H1 and H2 heat the platen drum 30 to raise its temperature.

[0038] Next, the electrical configuration for controlling the printer 1 will be described.

[0039] Figure 2 To schematically illustrate the control Figure 1 The printer 1 is operated by Figure 2The host computer 10 shown in the figure controls the printer 1. In the host computer 10, the main control unit 100, which oversees overall control operations, is composed of a CPU (Central Processing Unit) and memory. The host computer 10 is also equipped with a driver 120 that reads a program 124 from a medium 122. The medium 122 can be a variety of media, such as a CD (Compact Disk), a DVD (Digital Versatile Disk), or a USB (Universal Serial Bus) memory. The main control unit 100 controls the various components of the host computer 10 and the printer 1 based on the program 124 read from the medium 122.

[0040] Furthermore, the host computer 10 is provided with a monitor 130 composed of a liquid crystal display, etc., and an operating unit 140 composed of a keyboard, mouse, etc., as an interface with the operator. In addition to the image of the print target, the monitor 130 also displays a menu screen. Therefore, the operator can operate the operating unit 140 while checking the monitor 130 to open the print setting screen from the menu screen and set various printing conditions such as the type of print medium, the size of the print medium, and the print quality. It should be noted that the specific structure of the interface with the operator can be modified in various ways. For example, a touch panel display can be used as the monitor 130, and the operating unit 140 can be configured using the touch panel of the monitor 130.

[0041] Meanwhile, the printer 1 is equipped with a printer control unit 200 that controls various components of the printer 1 based on commands from the host computer 10. The printer control unit 200 also controls the recording head, UV lamp, and various components of the sheet conveyance system. Details of how the printer control unit 200 controls these components are as follows. The printer control unit 200 includes a memory MR as a storage unit. It should be noted that the printer control unit 200 corresponds to the control unit of the present invention.

[0042] The printer control unit 200 is responsible for controlling the use of Figure 1The function of conveying the sheet S is described in detail. That is, the motor is connected to the feed shaft 20, the front drive roller 31, the rear drive roller 32, and the take-up shaft 40, which are components constituting the sheet conveying system. Furthermore, the printer control unit 200 uses the detection results of various sensors SS to rotate each motor MM while controlling the speed and torque of each motor MM to control the conveyance of the sheet S. In addition, the printer control unit 200 is equipped with a temperature sensor TS for measuring the surface temperature of the platen drum 30. The temperature sensor TS measures the surface temperature of the platen drum 30, and the sheet S is conveyed in a manner that contacts the surface of the platen drum 30, so that the temperature of the recording medium and the platen drum 30 are substantially the same.

[0043] Figure 3 This graph shows the time-dependent temperature changes of the platen drum 30 from the start of printing when executing three jobs (Job A, Job B, and Job C) with different print duty cycles. Assuming the ambient temperature at startup, the temperature of the platen drum 30 rises as printing continues due to the heat of reaction generated by irradiating the photocurable ink with ultraviolet light. However, as is known, due to the influence of natural heat dissipation, the temperature rises with each print duty cycle, but after a predetermined period of time, it maintains a constant saturation temperature.

[0044] As mentioned above, the way ink spreads and wets varies depending on the temperature of the print medium or support, affecting image quality. Therefore, a larger difference between the temperature at the start of printing and the saturation temperature can significantly increase the difference in image quality. Therefore, to maintain a consistent difference in image quality, for example, within a color difference of ΔE = 1.0 degrees, which is difficult for humans to visually perceive, the difference between the temperature at the start of printing and the saturation temperature must be kept within a constant range.

[0045] Figure 4 The relationship between the saturation temperature and the preheating temperature of the job at different printing duty ratios in three stages is shown.

[0046] Different printing duty cycles result in different saturation temperatures. The temperature at the start of printing, where the difference between image quality at each saturation temperature and the image quality at the start of printing falls within a color difference range of less than ΔE = 1.0 degrees, can be determined experimentally. This temperature is shown as the preheating temperature in the figure. By preheating the platen drum 30 before printing, the difference between the temperature at the start of printing and the saturation temperature can be reduced, resulting in image quality at the start of printing that does not deviate significantly from that at the saturation temperature.

[0047] If the color difference ΔE is less than 1.0 degrees, it is difficult for humans to visually recognize it. This means that in one print job, the image quality difference between a printed product at a certain time and other printed products cannot be recognized. In other words, the user perceives that the printed product is basically constant.

[0048] exist Figure 4 In the example shown, the saturation temperature increases with higher print duty cycles. This relationship is consistent with the assumption that the heat of reaction is proportional to the unit mass of the photocurable ink. Furthermore, the preheating temperature remains 5°C below the saturation temperature regardless of the print duty cycle.

[0049] The saturation temperature and preheating temperature for high (75%), medium (50%), and low (30%) print duty ratios were determined experimentally. However, when the print duty ratio differs from these values, they are determined by interpolation. While interpolation equations are not listed, they can be a simple equation that takes the average value as the proportional gradient, or a curve that smoothly connects the three points can be obtained and used as the interpolation equation.

[0050] Alternatively, instead of performing the calculation every time during printing, the calculation may be performed in advance in 1% increments and stored in a table. Storing the calculation in a table is a storage relation, indicating that the calculation expression is a storage relation.

[0051] Since the saturation temperature becomes higher as the printing duty cycle of the operation is higher, basically, if the first temperature is used as the pre-heating temperature when the printing duty cycle is the first duty cycle value, then it can be said that the second temperature higher than the first temperature is used as the pre-heating temperature when the printing duty cycle is the second duty cycle value higher than the first duty cycle value.

[0052] The saturation temperature refers to the temperature at which the support portion reaches saturation when the process of curing the photocurable ink by continuously irradiating light from the light irradiation unit onto the recording medium after printing an image is performed. If the difference in image quality change is understood as a change in image color, then to keep the chromaticity change ΔE within a constant value, it is equivalent to starting printing when the temperature changes from the saturation temperature to the constant temperature range. Therefore, the preheating temperature is set to a temperature that is different from the saturation temperature at which the support portion temperature reaches saturation by a first differential temperature. When the saturation temperature is set to the first temperature, the preheating temperature can be said to be a temperature that is different from the saturation temperature by the first differential temperature. When the saturation temperature is set to the second temperature, the preheating temperature can be said to be a temperature that is different from the saturation temperature by the second differential temperature.

[0053] in the case of Figure 4 In the example shown, the first temperature difference and the second temperature difference are the same value, but they are not limited to being the same.

[0054] Other experimental results show that when the saturation temperature is high, the magnitude of the saturation temperature increase is disproportionate to the magnitude of the image quality change. As the saturation temperature rises, the magnitude of the image quality change moderates. In other words, in areas with high saturation temperatures, the first temperature difference when the saturation temperature is low is lower than the second temperature difference when the saturation temperature is higher. In other words, the second temperature difference becomes higher.

[0055] As described above, the color difference ΔE between an image printed at the saturation temperature and an image printed at a preheating temperature different from the saturation temperature by a first difference temperature is set to less than 1.0 so that the color difference is not noticeable to ordinary people.

[0056] However, the permissible image quality variation range may be set in advance through a user interface, and when the user reduces the image quality variation range, the first and second temperature differences may be set to be smaller than when the variation range is increased.

[0057] Next, the operation of this embodiment having the above-described configuration will be described.

[0058] Figure 5 This is a flowchart of the printer control unit.

[0059] The printer control unit 200 selects an image in step S100. This is equivalent to printing an image from the user. If the user instructs printing, the printer control unit 200 recognizes the print image and selects the image. Next, in step S105, the printer control unit 200 distributes the selected image to the recording medium. Originally, printing would start in this manner, but in the present invention, the printer control unit 200 calculates the average printing duty cycle within a specified range in step S110. Since the printing duty cycle varies depending on the location, the average printing duty cycle within the specified range is calculated. The heat generated by the photocurable ink can be considered to be proportional to the total amount of ink ejected.

[0060] If considered more strictly, the calorific value can also be calculated for each ink color and reflected in the calorific value. For example, when the ink color has a large calorific value, a larger correction may be made to the average printing duty cycle.

[0061] And, as Figure 1 As shown, in this embodiment, the curable ink ejected from the four color recording heads 51 of the ejection unit is temporarily cured. However, the amount of heat applied to the platen drum 30 by this heat generation differs depending on the position of the four color recording heads 51. Specifically, the weighting of the printing duty cycle for the first ejected ink color may be increased because the heat generated by the heating platen drum 30 is greater, while the weighting of the printing duty cycle for the last ejected ink color may be decreased because the heat generated by the heating platen drum 30 is less.

[0062] Next, in step S115, the printer control unit 200 uses the average print duty cycle as input and references a table to determine the saturation temperature and drum preheating temperature. In this embodiment, since the saturation temperature and drum preheating temperature for each print duty cycle are stored as a table, the printer control unit 200 uses the average print duty cycle as input and references the table to determine the saturation temperature and drum preheating temperature.

[0063] In step S120 , the printer control unit 200 checks the current drum temperature based on the measurement result of the temperature sensor TS. Then, in step S125 , the drum is heated or cooled until the temperature reaches the saturation temperature or the drum preheating temperature, whichever is closer to the current drum temperature.

[0064] Reference Figure 4 The following example illustrates this.

[0065] In step S110 , if the average print duty ratio calculated by the printer control unit 200 is 50%, the saturation temperature calculated in step S115 is 38°C, and the preheating temperature is set to 33°C based on this. Furthermore, in step S120 , the temperature of the platen drum 30 is set to 25°C.

[0066] Based on the information that the current drum temperature is 25 degrees, the saturation temperature is 38 degrees, and the preheating temperature is 33 degrees, the printer control unit 200 can determine that the current drum temperature is closer to the preheating temperature than the saturation temperature, and in order to make the current drum temperature reach the preheating temperature, the printer control unit 200 starts heating the paper platen drum 30 through the heaters H1 and H2.

[0067] The printer control unit 200 waits until the current drum temperature reaches the preheating temperature. If the current drum temperature reaches the preheating temperature, printing begins in step S130. It should be noted that in this embodiment, feedback control is performed, but a simple feedforward control method without using the measurement results of the temperature sensor TS may also be used.

[0068] On the other hand, there are cases where printing jobs are continuous. In this case, the average printing duty ratio of the preceding printing job is set to a high 75%, and the average printing duty ratio of the following printing job is set to a low 30%.

[0069] In this case, at the start of the subsequent printing job, the current drum temperature of the platen drum 30 is 41°C, the saturation temperature at an average print duty cycle of 75%. In this case, in step S125, based on the information that the current drum temperature is 41°C, the saturation temperature is 38°C, and the preheating temperature is 33°C, it is determined that the current drum temperature is closer to the saturation temperature than the preheating temperature. Fans F1 and F2 begin cooling the platen drum 30 to bring the current drum temperature to the saturation temperature.

[0070] Then, when the drum is cooled until the current temperature reaches the saturation temperature, the printer control unit 200 starts printing in step S130 .

[0071] In this embodiment, if cooling is required, cooling is performed and the machine waits until the saturation temperature is reached. If heating is required, the machine waits until the preliminary heating temperature, which is lower than the saturation temperature, is reached. However, a preliminary (cooling) temperature may be set that allows printing to start before the saturation temperature is reached even when cooling is required. Printing may be started before the platen drum 30 reaches the saturation temperature, and printing may be performed while the temperature is gradually lowered to the saturation temperature.

[0072] Figure 6 This is a flowchart of the printer control unit according to a modified example.

[0073] exist Figure 5 In the flowchart shown, in step S115, the average printing duty ratio is used as input to perform table reference to obtain the saturation temperature and the preheating temperature. Figure 6 In the process of the flowchart shown in FIG. 2 , in step S215 , the calculation formula is executed with the average printing duty ratio as a parameter to obtain the saturation temperature and the drum preheating temperature. Figure 6 In the flowchart shown, the difference lies in that the calculation process is performed based on the parameters each time, and the other processes are the same.

[0074] As described above, the invention can be understood as a printer including the printer control unit 200 as a printing device. Figure 5 、 Figure 6 The present invention is understood as a printing method by which each process executed by the printer control unit 200 over a period of time as shown above is performed.

[0075] That is, it can be said that in the printer 1 of this embodiment,

[0076] pre-storing at least one of a relationship between the printing duty ratio of the image and the pre-heating temperature and a relational expression representing the relationship between the printing duty ratio of the image and the pre-heating temperature;

[0077] Implementing: a process of obtaining the printing duty cycle of the printed image; and

[0078] The step of adjusting the temperature adjustment unit so that the support unit reaches the preheating temperature based on the acquired printing duty ratio and the relationship or the relationship expression stored in the storage unit.

[0079] It should be noted that the present invention is obviously not limited to the above-mentioned embodiment. Although it is obvious to those skilled in the art, the following content is disclosed as an embodiment of the present invention.

[0080] The interchangeable components and structures disclosed in the above embodiments may be appropriately combined and applied;

[0081] Components and structures that are not disclosed in the above embodiments but are well-known technologies and can be replaced with the components and structures disclosed in the above embodiments, or their combination can be changed and applied;

[0082] Although not disclosed in the above embodiments, those skilled in the art can assume that they are substitutes for the components and components disclosed in the above embodiments based on known technologies, etc., and their combinations can be appropriately replaced or applied in a modified manner.

Claims

1. A printing device, characterized in that have: Conveying unit; conveying recording medium; a supporting portion that supports the recording medium transported by the transport portion; a discharge portion located at a position facing the support portion and configured to discharge photocurable ink onto the recording medium supported by the support portion to form an image; a light irradiation unit that irradiates the light-curable ink ejected onto the recording medium with light to cure the ink, located downstream of the ejection unit and on a conveyance path for the recording medium; a temperature adjustment unit capable of at least one of cooling and heating the support unit; a storage unit storing at least one of a relationship between the printing duty ratio and the preheating temperature and a relational expression representing the relationship between the printing duty ratio and the preheating temperature; and Control Department, The relationship or the relationship expression is based on the printing duty cycle and a saturation temperature, wherein the saturation temperature is a temperature at which the temperature of the support portion rises to saturation when a process of printing on the recording medium with the photocurable ink and curing the photocurable ink by irradiating light from the light irradiation portion onto the recording medium on which the image is printed is continuously performed. The control unit obtains the printing duty cycle of the printed image, and adjusts the temperature adjustment unit based on the obtained printing duty cycle and the relationship or the relationship expression stored in the storage unit so that the recording medium or the support unit reaches the preheating temperature.

2. The printing device according to claim 1, wherein In the relationship or the relationship expression stored in the storage unit, when the printing duty cycle is a first duty cycle value, a first temperature corresponds to the pre-heating temperature, and when the printing duty cycle is a second duty cycle value higher than the first duty cycle value, a second temperature higher than the first temperature corresponds to the pre-heating temperature.

3. The printing device according to claim 2, wherein: The first temperature based on the relationship or the relationship expression stored in the storage unit is a temperature that is different by a first difference temperature from a saturation temperature at which the temperature of the support portion rises to saturation when the image having the first duty cycle value is continuously printed on the recording medium using the photocurable ink and the photocurable ink is cured by irradiating light from the light irradiation unit onto the recording medium on which the image is printed. The second temperature based on the relationship or the relationship expression stored in the storage unit is a temperature that is different from the saturation temperature when the temperature of the support portion rises to saturation by a second difference temperature when the image of the second duty cycle value is continuously printed on the recording medium using the photocurable ink, and the photocurable ink is cured by irradiating light from the light irradiation unit to the recording medium after the image is printed.

4. The printing device according to claim 3, wherein The first difference temperature and the second difference temperature are the same value.

5. The printing device according to claim 3, wherein The first temperature difference is lower than the second temperature difference.

6. The printing device according to any one of claims 3 to 5, characterized in that A color difference ΔE between an image printed at the saturation temperature and an image printed at a temperature different from the saturation temperature by the first difference temperature is less than 1.

0.

7. The printing device according to any one of claims 3 to 5, characterized in that When the image quality variation range is reduced based on the setting related to the image quality variation range, the values ​​of the first temperature difference and the second temperature difference are reduced.

8. The printing device according to claim 1, wherein The printing device includes a temperature sensor for measuring the temperature of the recording medium or the support portion, and the control portion adjusts the temperature adjustment portion based on a measurement result of the temperature sensor so that the recording medium or the support portion reaches the preheating temperature.

9. A printing method, characterized in that: A printing method using a printing device, the printing device comprising: a conveying unit for conveying a recording medium; a supporting unit for supporting the recording medium conveyed by the conveying unit; a discharge unit located opposite the supporting unit and discharging a photocurable ink onto the recording medium supported by the supporting unit to form an image; and a light irradiation unit located downstream of the discharge unit in a conveyance path of the recording medium and irradiating the photocurable ink discharged onto the recording medium with light to cure the ink. a temperature adjustment unit capable of at least one of cooling and heating the support unit; and a control unit, In the printing method, at least one of a relationship between the printing duty ratio and the preheating temperature and a relational expression representing the relationship between the printing duty ratio and the preheating temperature is stored in advance. The relationship or the relationship expression is based on the printing duty cycle and a saturation temperature, wherein the saturation temperature is a temperature at which the temperature of the support portion rises to saturation when a process of printing on the recording medium with the photocurable ink and curing the photocurable ink by irradiating light from the light irradiation portion onto the recording medium on which the image is printed is continuously performed. In the printing method, the following steps are performed: a step of obtaining the printing duty cycle of the printed image; as well as The step of adjusting the temperature adjustment unit based on the acquired printing duty ratio and the stored relationship or relationship expression so that the support unit reaches the preheating temperature.

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