Liquid ejection head and liquid ejection device

Abstract

To provide a liquid discharging head and a liquid discharging device capable of suppressing unnecessary energy consumption and efficiently suppressing dew condensation caused on a discharge port surface (recording element board).SOLUTION: A liquid discharging head 30A includes a recording element board 10 provided with a discharge port surface 10a on which a plurality of discharge ports are arranged, and a temperature controlling means which controls a temperature of the discharge port surface 10a. The discharge ports of the recording element board 10 discharge liquid to medium to be discharged which is relatively displaced with respect to the liquid discharging head 30A. The temperature controlling means adjusts the temperature of the discharge port surface 10a so that the temperature on an area of the downstream side of the discharge port surface 10a becomes higher than the temperature on the area of the upstream side of the discharge port surface 10a with respect to the relative movement direction of the medium to be discharged when seeing the medium to be discharged from the liquid discharging head 30A.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a liquid ejection device that ejects liquid such as ink toward an ejection receiving medium. [Background technology]

[0002] In general, in a liquid ejection device, the liquid ejection head ejects liquid toward the ejection receiving medium while the liquid ejection head and the ejection receiving medium are moved relative to each other. At this time, the water content of the liquid that has landed on the ejection receiving medium evaporates, and condensation may form on the surface of the liquid ejection head where the ejection ports are formed (the ejection port surface of the recording element substrate). Patent Document 1 describes an inkjet printer that can prevent the above-mentioned condensation. This inkjet printer includes a head heating unit that heats the lower surface of the head to a temperature higher than the dew point temperature. Furthermore, Patent Document 2 describes a liquid ejection device that can prevent the above-mentioned condensation. This liquid ejection device includes a platen that faces the liquid ejection head and supports the recording medium. This platen includes multiple heating units that are arranged side by side in a continuous line along the recording medium transport direction. By setting the temperature of the heating units that do not overlap the recording medium higher than the temperature of the heating units that overlap the recording medium, it is possible to heat the nozzle surface while heating the recording medium to an appropriate temperature. Heating the nozzle surface can suppress condensation. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2005-22160 [Patent Document 2] Japanese Patent Application Publication No. 2019-81306 Summary of the Invention [Problem to be solved by the invention]

[0004] As a result of verification by the inventors, it was found that condensation on the ejection port surface tends to be more pronounced in the downstream region in the direction of movement of the ejection receiving medium when viewed from the liquid ejection head. In other words, condensation is less likely to occur in the upstream region of the ejection port surface. In the inkjet printer described in Patent Document 1, the head heating means uniformly heats the entire underside of the head. In the liquid ejecting device described in Patent Document 2, the entire nozzle surface is also uniformly heated. Therefore, these technologies require a large amount of energy consumption to prevent condensation.

[0005] An object of the present invention is to reduce unnecessary energy consumption and efficiently prevent condensation from forming on the ejection port surface (printing element substrate). [Means for solving the problem]

[0006] In order to achieve the above object, according to one aspect of the present invention, a liquid ejection head includes an ejection port surface on which a plurality of ejection ports are arranged. and, the above The ejection port surface is divided into a plurality of adjustment areas, and a temperature sensor for detecting a temperature in each adjustment area and a temperature control heater for heating the adjustment area are provided. a temperature control means for adjusting the temperature of the ejection port surface; A recording element substrate comprising: The ejection openings of the recording element substrate eject liquid onto an ejection receiving medium that moves relatively to the liquid ejection head. The temperatures of the plurality of adjustment areas can be individually adjusted, and the temperature control heater is driven based on the detection value of the temperature sensor, The temperature of the ejection port surface is adjusted so that the temperature of the downstream area of ​​the ejection port surface is higher than the temperature of the upstream area of ​​the ejection port surface in the relative movement direction of the ejection medium when viewed from the liquid ejection head. According to another aspect of the present invention, a liquid ejection head includes a recording element substrate having an ejection orifice surface on which a plurality of ejection orifices are arranged, and a temperature control unit for controlling the temperature of the ejection orifice surface. Relative to the liquid ejection head Liquid is ejected onto a moving ejection receiving medium. The temperature adjustment unit adjusts the temperature of the ejection port surface so that the temperature of a region downstream of the ejection port surface is higher than the temperature of a region upstream of the ejection port surface in the direction of relative movement of the ejection receiving medium when the ejection receiving medium is viewed from the liquid ejection head. In the downstream region of the ejection port surface, the thickness of a laminar boundary layer formed on the ejection receiving medium by water evaporation from the liquid that has landed on the ejection receiving medium is greater than the distance between the ejection receiving medium and the ejection port surface. Let the length of the recording element substrate in the direction of relative movement of the ejection receiving medium be x0 (mm), the height from the ejection receiving medium to the recording element substrate be h (mm), the moving speed of the ejection receiving medium be U0 (m / s), and the kinetic viscosity of air be ν (m 2 / s), the length x0 of the recording element substrate is x0>0.0333×h 2 ×U0 / ν .

[0007] BookAccording to yet another aspect of the present invention, a liquid ejection device includes a plurality of liquid ejection heads each having an ejection port surface on which a plurality of ejection ports are arranged, each ejecting a liquid onto a moving ejection receiving medium, and a temperature control unit that individually adjusts the temperature of the ejection port surface of each of the plurality of liquid ejection heads. The plurality of liquid ejection heads are arranged in parallel from upstream to downstream in the direction of movement of the ejection receiving medium. Each of the plurality of liquid ejection heads has The temperature adjusting means adjusts the temperature of the ejection port surface of the liquid ejection head so that it becomes higher toward the downstream side. [Effects of the Invention]

[0008] According to the present invention, it is possible to suppress unnecessary energy consumption and efficiently suppress condensation on the ejection port surface (printing element substrate). [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a front view schematically showing a recording apparatus according to a first embodiment of the present invention. [Figure 2] FIG. 2 is a perspective view of a recording unit. [Figure 3] FIG. 4 is a schematic diagram showing the movement of a recording unit. [Figure 4] 10A to 10C are diagrams illustrating an example of a process of a recording operation. [Figure 5] 5A and 5B are schematic diagrams for explaining condensation on a printing element substrate and temperature control. [Figure 6] 5A and 5B are schematic diagrams for explaining the surface temperature of the recording element substrate during temperature control. [Figure 7] FIG. 2 is a schematic diagram for explaining the thickness of a laminar boundary layer. [Figure 8] FIG. 10 is a schematic diagram showing the configuration of a recording apparatus according to a second embodiment of the present invention. [Figure 9] FIG. 10 is a schematic diagram showing the configuration of a recording apparatus according to a third embodiment of the present invention. [Figure 10] FIG. 10 is a schematic diagram showing the configuration of a recording apparatus according to a fourth embodiment of the present invention. [Figure 11]FIG. 10 is a schematic diagram showing the configuration of a recording apparatus according to a fifth embodiment of the present invention. [Figure 12] 1 is a perspective view of a liquid ejection head according to a first embodiment of the present invention. [Figure 13] FIG. 2 is a schematic diagram of an ejection port surface of a recording element substrate. [Figure 14] FIG. 14 is an enlarged view of the portion enclosed by the circle shown in FIG. [Figure 15] FIG. 2 is a schematic diagram of a platen equipped with a temperature-controlling heater. [Figure 16] FIG. 2 is a schematic diagram showing a configuration for circulating ink to be supplied to a liquid ejection head. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiments are merely examples and are not intended to limit the scope of the present invention. In this specification and drawings, components having the same function may be designated by the same reference numerals to avoid redundant description. In the following embodiments, a liquid ejection head and a liquid ejection apparatus that perform recording by ejecting liquid will be described. Furthermore, in this specification, moving the liquid ejection head and the ejection receiving medium relative to each other includes moving the ejection receiving medium while the liquid ejection head is stationary (Mode 1) and moving the liquid ejection head while the ejection receiving medium is stationary (Mode 2). In Mode 1, the relative movement direction of the ejection receiving medium when viewed from the liquid ejection head corresponds to the movement direction of the ejection receiving medium. In this case, upstream and downstream are defined with respect to the movement direction of the ejection receiving medium. On the other hand, in Mode 2, the relative movement direction of the ejection receiving medium when viewed from the liquid ejection head corresponds to the opposite direction to the movement direction of the liquid ejection head. When viewed from the liquid ejection head, the stationary ejection receiving medium appears to be moving in the opposite direction to the movement direction of the liquid ejection head (see the operation explanation in Figures 10(a) and 10(b) described later). Therefore, in Mode 2, upstream and downstream are defined with respect to this apparent movement direction of the ejection receiving medium. Note that the ejection receiving medium may be any medium to which liquid can be applied, such as a transfer body or a recording medium.

[0011] (First embodiment) (Overall description of the recording device) FIG. 1 is a front view schematically illustrating a recording apparatus 1 according to a first embodiment of the present invention. The recording apparatus 1 is a sheet-fed inkjet printer (liquid ejection apparatus) that produces a recorded matter P2 by transferring a liquid image, such as ink, to a recording medium P1 via a transfer body 2. The recording apparatus 1 includes a recording mechanism 1A and a transport mechanism 1B. In this embodiment, the X, Y, and Z directions respectively indicate the width (total length), depth, and height directions of the recording apparatus 1. Here, arrows X and Y indicate horizontal directions and are perpendicular to each other. Arrow Z indicates the up-down direction. The recording medium P1 is transported in the X direction. The recording mechanism 1A includes a recording unit 3, a transfer unit 4, peripheral units 5A to 5D, and a supply unit 6. The recording unit 3 includes multiple recording heads 30 and a carriage 31. The recording heads 30 are liquid ejection heads.

[0012] (Recording unit description) FIG. 2 is a perspective view of the recording unit 3. The recording head 30 ejects liquid, such as ink, toward the transfer body 2, which is a receiving medium, and forms a liquid image, which serves as a recorded image, on the receiving medium, i.e., the transfer body 2. In this embodiment, the recording head 30 is a full-line head extending in the Y direction, and multiple recording element substrates are arranged across the entire printable area in the width direction of the largest usable recording medium. The recording head 30 is fixed to a carriage 31 and has an ejection port surface on its underside, where ejection ports are open. The ejection port surface faces the surface of the transfer body 2 via a small gap. The small gap is, for example, several millimeters (specifically, 2 mm). The transfer body 2 is attached to the outer periphery of a rotating cylindrical transfer drum 41 and moves cyclically on a circular orbit that coincides with the outer periphery of the transfer drum 41 in accordance with the rotation of the transfer drum 41. The multiple recording heads 30 are arranged radially along the circular orbit of the transfer body 2, i.e., along the outer periphery of the transfer drum 41.

[0013] In this embodiment, nine recording heads 30 are provided, each ejecting a different type of ink. The different types of ink are, for example, inks with different color materials, such as yellow ink, magenta ink, cyan ink, and black ink. In this embodiment, one recording head 30 is configured to eject one type of ink, but this is not limited to this. One recording head 30 may also be configured to eject multiple types of ink. Furthermore, some of the multiple recording heads 30 may eject ink that does not contain a color material (for example, clear ink).

[0014] (Explanation of head recovery position and ejection position) The carriage 31 carries each recording head 30. Sliders 32 are provided on both sides of the carriage 31 in the X direction for moving the carriage 31 in the Y direction. FIG. 3 is a schematic diagram showing the movement of the recording unit 3. FIG. 3 shows the recording apparatus 1 as viewed from the right side. The recording unit 3 is guided along a guide member RL and is movable between a discharge position POS1 and a recovery position POS3. At the discharge position POS1, the recording unit 3 performs a discharge operation. At the recovery position POS3, a recovery unit 12 performs a process to recover the discharge performance of the recording head 30.

[0015] (peripheral units) Peripheral units 5A to 5D are arranged along the outer circumferential surface of transfer cylinder 41, and are a toner application unit, an absorption unit, a heating unit, and a cleaning unit, respectively. The application unit 5A is a mechanism that applies a reaction liquid onto the transfer body 2 before the recording unit 3 ejects ink. The reaction liquid is a liquid containing a component that increases the viscosity of the ink. Here, increasing the viscosity of the ink means that the coloring material, resin, etc. that make up the ink come into contact with the component that increases the viscosity of the ink and chemically react or physically adsorb to it, thereby increasing the viscosity of the ink. This increase in viscosity of the ink includes not only an increase in the viscosity of the ink as a whole, but also a local increase in viscosity caused by aggregation of some of the components that make up the ink, such as the coloring material or resin.

[0016] The absorbing unit 5B is a mechanism that absorbs liquid components from the ink image (image) on the transfer body 2 before transfer. The absorbing unit 5B includes, for example, a liquid absorbing member that comes into contact with the ink image to reduce the amount of liquid components in the ink image. The liquid absorbing member may be a member formed on the outer circumferential surface of a roller. Alternatively, the liquid absorbing member may be an endless belt-like sheet made of a porous material. From the viewpoint of protecting the ink image, the moving speed of the liquid absorbing member may be set to the same as the peripheral speed of the transfer body 2, so that the liquid absorbing member moves in synchronization with the transfer body 2.

[0017] The heating unit 5C is a mechanism for heating the ink image on the transfer body 2 before transfer. Heating the ink image melts the resin in the ink image, improving its transferability to the recording medium P. The heating temperature can be set to a temperature equal to or higher than the minimum film-forming temperature (MFT) of the resin. The MFT can be measured using a commonly known method, for example, using an apparatus conforming to JIS K 6828-2:2003 or ISO 2115:1996. From the viewpoint of transferability and image robustness, heating may be performed at a temperature 10°C or higher than the MFT, or even 20°C or higher than the MFT. In this embodiment, heating is performed to approximately 110°C to 120°C. Known heating devices such as various infrared lamps and hot air fans can be used for the heating unit 5C. Furthermore, from the viewpoint of heating efficiency, an infrared heater may also be used. The cleaning unit 5D is a mechanism that cleans the surface of the transfer body 2 after transfer. The cleaning unit 5D removes ink remaining on the transfer body 2, dust, etc. The cleaning unit 5D can appropriately use known methods such as a method of bringing a porous member into contact with the transfer body 2, a method of rubbing the surface of the transfer body 2 with a brush, or a method of scraping the surface of the transfer body 2 with a blade. The cleaning member used for cleaning can have known shapes such as a roller shape or a web shape.

[0018] (supply unit) The supply unit 6 is a mechanism for supplying ink to each recording head 30 of the recording unit 3. The supply unit 6 includes a storage section TK for storing ink for each type of ink and a flow path 6a. The ink is supplied from the storage section TK to the recording head 30 via the flow path 6a. The storage section TK may be composed of a main tank and a sub-tank. The flow path 6a may be a flow path for circulating ink between the storage section TK and the recording head 30. The supply unit 6 may be provided with a pump for supplying ink. In addition, a degassing mechanism for degassing air bubbles in the ink and a valve for adjusting the liquid pressure of the ink and atmospheric pressure may be provided midway along the flow path 6a or in the storage section TK. The heights of the storage section TK and the recording head 30 in the Z direction may be set so that the ink level in the storage section TK is lower than the ink ejection surface of the recording head 30.

[0019] (Transport mechanism) The transport mechanism 1B feeds the recording medium P1 to the transfer unit 4 and discharges the recorded material P2, onto which the ink image has been transferred, from the transfer unit 4. In Figure 1, the arrows indicate the rotation direction of each member of the transport mechanism 1B and the transport paths of the recording medium P1 and the recorded material P2. In this transport mechanism 1B, the recording medium P1 is transported from the feeding unit 7 to the transfer unit 4, and the recorded material P2 is transported from the transfer unit 4 to the collection unit 9.

[0020] (Explanation of recording operation) 4 is a diagram showing a typical example of the steps of the recording operation. While the transfer cylinder 41 and the impression cylinder 42 rotate, the following steps are cyclically carried out. First, the reaction liquid L is applied from the application unit 5A onto the transfer body 2 (ST1). As the transfer cylinder 41 rotates, the area on the transfer body 2 to which the reaction liquid L has been applied reaches a position facing the recording head 30, and ink is ejected from the recording head 30 onto the transfer body 2 to form an ink image IM (ST2). At this time, the ejected ink mixes with the reaction liquid L on the transfer body 2, promoting aggregation of the colorant.

[0021] As the transfer body 2 rotates, the ink image IM on the transfer body 2 reaches a position opposite the absorbing unit 5B, which absorbs the liquid components from the ink image IM by contacting the transfer body 2 (ST3). As the transfer body 2 further rotates, the ink image IM reaches a position opposite the heating unit 5C, where it is heated to approximately 110°C to 120°C by the heating unit 5C, melting the resin in the ink image IM and forming a film (ST4). Synchronously with the formation of the ink image IM, the conveying mechanism 1B conveys the recording medium P1. When the ink image IM and the recording medium P1 reach the nip between the transfer body 2 and the impression cylinder 42, the ink image IM is transferred to the recording medium P1, producing a recorded product P2 (ST5). After transfer, as the transfer body 2 rotates, the portion of the transfer body 2 where the ink image IM was formed reaches a position opposite the cleaning unit 5D, where it is cleaned by the cleaning unit 5D (ST6). By repeating these steps ST1 to ST6, a plurality of recorded matters P2 are produced. In the above description of the recording operation, an example was given in which an ink image IM is transferred once to one recording medium P1 with one rotation of the transfer body 2, but it is also possible to continuously transfer ink images IM to multiple recording media P1 with one rotation of the transfer body 2.

[0022] (Explanation of liquid ejection head) Next, the configuration of the liquid ejection head 30A used as the recording head 30 will be described in detail. Figure 12 is a perspective view of a liquid ejection head 30A according to this embodiment. Figure 12(a) is a view of the liquid ejection head 30A viewed from diagonally below the side from which the liquid is ejected. Figure 12(b) is a view of the liquid ejection head 30A viewed from diagonally above the side opposite to the side from which the liquid is ejected. The liquid ejection head 30A shown in Figures 12(a) and 12(b) is an inkjet line-type recording head capable of recording with one color liquid. The liquid ejection head 30A includes multiple recording element substrates 10, a liquid connection section 111, an electrical wiring substrate 90, a shield plate 132, a signal input terminal 91, and a power supply terminal 92. The multiple recording element substrates 10 are arranged in a straight line in the longitudinal direction of the liquid ejection head 30A. The signal input terminal 91 and the power supply terminal 92 are arranged along the longitudinal direction of the liquid ejection head 30A. This makes it possible to reduce voltage drops and signal transmission delays that occur in the wiring sections provided on the recording element substrates 10.

[0023] Next, the recording element substrate 10 will be described with reference to FIGS. FIG. 13 is a schematic diagram of the ejection port surface 10a of the recording element substrate 10, on which the ejection ports 13 are provided. The recording element substrate 10 has a generally parallelogram shape and has the ejection port surface 10a on which a plurality of ejection ports 13 are arranged in a row. A plurality of ejection port arrays are arranged in parallel on the ejection port surface 10a. Terminals 16 for electrical connection with the control unit of the recording device 1 are provided at both ends of the ejection port surface 10a. Although not shown, a liquid supply path is provided for each ejection port array. A plurality of pressure chambers communicate with the liquid supply path, and each pressure chamber is provided with an ejection port 13. An energy generating element (not shown) is provided within the pressure chamber to generate energy for ejecting liquid from the ejection port 13. An energy generating element is provided for each ejection port. Examples of the energy generating element include a heat generating element that causes the liquid to bubble using thermal energy, and a piezoelectric element including a piezoelectric body. The energy generating element is electrically connected to the terminals 16 by electrical wiring. Liquid is supplied to each of the ejection ports 13 through the liquid supply path, and the liquid is ejected from each of the ejection ports 13 in accordance with a control signal from the control unit of the recording apparatus 1.

[0024] FIG. 14 is an enlarged view of the ejection port 13 and its surrounding area enclosed within a circle in FIG. 13. FIG. 14 schematically illustrates the positional relationship between the adjustment area 11 for temperature control, the temperature control heater 15, and the temperature sensor 14. The ejection port surface 10a is divided into multiple adjustment areas 11. Here, multiple adjustment areas 11 are provided so as to divide the ejection port array 8 into multiple areas. In each adjustment area 11, a temperature control heater 15 and a temperature sensor 14 are provided at a distance so as not to affect each other's operations. The temperature sensor 14 detects the surface temperature of the adjustment area 11 and is provided directly below the ejection port surface 10a where the ejection ports 13 are formed. The temperature control heater 15 can heat the adjustment area 11. In each adjustment area 11, when the detection value of the temperature sensor 14 falls below a preset threshold, the temperature control heater 15 is driven to heat the adjustment area 11. When the detection value of the temperature sensor 14 exceeds the threshold, heating by the temperature control heater 15 is stopped. This allows the adjustment area 11 to be maintained at a temperature according to the threshold value.

[0025] It is possible to set a threshold value for each adjustment area 11 individually, and to set each adjustment area 11 to any temperature. That is, the controlled temperature of the ejection port surface 10a can be set or changed for each adjustment area. Also, by constantly setting the controlled temperature for each adjustment area, it is possible to change the controlled temperature in accordance with, for example, changes in the ambient temperature or changes in jobs related to recording operations (print jobs, etc.). The temperature sensor 14 and temperature control heater 15 of each adjustment area 11 constitute a temperature adjustment means 18. The temperature adjustment means 18 can adjust the temperature of the plurality of adjustment areas 11 individually, and can set a desired area of ​​the ejection port surface 10a to any temperature. For example, when the ejection port 13 ejects liquid onto a moving transfer body 2, the temperature adjustment means 18 adjusts the temperature of the ejection port surface 10a so that the temperature of the area downstream of the ejection port surface 10a in the direction of movement of the recording medium P is higher than the temperature of the area upstream of the ejection port surface 10a.

[0026] The temperature sensor 14 may be, for example, a diode sensor. In the example of FIG. 14, the shape of the temperature sensor 14 is elongated in the direction of the nozzle array, but is not limited to this. The shape of the temperature sensor 14 may be circular, square, or the like. In the example of FIG. 14, the nozzle surface 10a is heated using the temperature-control heater 15. However, instead, the nozzle surface 10a may be heated using a heat-generating element (energy-generating element) for discharging the liquid. In this case, the temperature control unit 18 drives the heat-generating element with power that does not generate bubbles during periods when the heat-generating element is not generating thermal energy for discharging the liquid. The heat-generating element can be used to heat a desired area of ​​the nozzle surface 10a. 14, the temperature-adjustable heater 15 is provided on the recording element substrate 10, but this is not limiting. As long as the ejection port surface 10a can be heated, the temperature-adjustable heater 15 may be provided on a member other than the recording element substrate 10, for example, a member facing the liquid ejection head 30A. For example, the temperature-adjustable heater 15 may be provided on a transfer body that temporarily holds an intermediate image to be transferred using the liquid ejected from the liquid ejection head 30A.

[0027] (Explanation of condensation caused by water evaporation and temperature control) Next, we will explain in detail the condensation that occurs on the recording element substrate 10 due to evaporation of water from the liquid applied to the transfer body 2, and the temperature control of the recording element substrate 10. For convenience, we will explain the condensation that occurs due to evaporation of water when the liquid ejection head ejects liquid onto the recording medium P moving at a transport speed U0, and the temperature control.

[0028] FIG. 5 is a schematic diagram illustrating condensation and temperature control of the recording element substrate 10. FIGS. 5(a) and 5(b) show the temperature control of a liquid ejection head 30B of a comparative example, and FIG. 5(c) shows the temperature control of a liquid ejection head 30A of this embodiment. The liquid ejection head 30B has the same structure as the liquid ejection head 30A described above, except for the temperature control. Both the liquid ejection head 30A and the liquid ejection head 30B include the recording element substrate 10 shown in FIG. 14. Figure 6 is a schematic diagram for explaining the temperature of the surface (ejection port surface 10a) of the recording element substrate 10 during temperature control. Figure 6(a) corresponds to the temperature control of the comparative example in Figure 5(a), Figure 6(b) corresponds to the temperature control of the comparative example in Figure 5(b), and Figure 6(c) corresponds to the temperature control of the present embodiment in Figure 5(c). In Figure 6, the surface temperature of the recording element substrate 10 is represented by light and dark shades, with the light areas representing approximately 65°C and the dark areas representing approximately 75°C.

[0029] First, the influence of the water vapor 22 on the recording element substrate 10a will be described with reference to a comparative example in FIG. 5(a). In the comparative example of FIG. 5(a), the recording medium P is transported so as to pass a position facing the liquid ejection head 30B. The liquid ejection head 30B ejects liquid 21a toward the moving recording medium P. The ejection port arrays 8 of the recording element substrate 10 are arranged so as to intersect with the transport direction of the recording medium P. That is, the ejection port arrays 8 are arranged in parallel from upstream to downstream in the transport direction of the recording medium P. In synchronization with the transport operation of the recording medium P, the liquid 21a is ejected sequentially from the upstream ejection port array 8. In this case, as the recording medium P is transported downstream, the amount of liquid 21b that lands on the recording medium P (adhesion amount) increases, and therefore the amount of evaporated water 22 increases downstream. As a result, condensation is more likely to occur in the downstream region of the recording element substrate 10. In other words, condensation is less likely to occur in the upstream region of the recording element substrate 10. Note that while the amount of evaporated water 22 increases when the recording medium P is heated, the amount of evaporated water 22 also occurs even when the recording medium P is not heated. If condensation occurs on the recording element substrate 10, ejection defects may occur if the ejected droplets protruding from the ejection ports 13 come into contact with the condensed droplets 23 during ejection, or if the condensed droplets 23 penetrate into the interior of the ejection ports 13. In this case, the quality of the recorded image is reduced.

[0030] Furthermore, the longer the recording element substrate 10 is in the direction of movement of the recording medium P, the greater the effect of the water evaporation 22, and as a result, the larger the area where condensation droplets 23 occur (condensation area). This condensation area depends on the relationship between the thickness of the laminar boundary layer formed on the recording medium P by the water evaporation 22 from the liquid that has landed on the recording medium P and the distance between the recording medium P and the recording element substrate 10. Here, the thickness of the laminar boundary layer will be explained. Figure 7 is a schematic diagram for explaining the thickness of a laminar boundary layer developed on a flat plate. The thickness δ of this laminar boundary layer is given by the following equation:

[0031]

number

[0032] The laminar boundary layer shown in FIG. 7 is also formed on the recording medium P due to the evaporated water 22. As a result of studies by the inventors, it was found that the influence of the evaporated water 22 on the recording element substrate 10 becomes greater when the thickness δ of the laminar boundary layer becomes greater than the distance between the recording medium P and the recording element substrate 10. Here, in both the liquid ejection head 30B and the liquid ejection head 30A shown in FIG. 5, the thickness δ of the laminar boundary layer is greater than the distance between the recording medium P and the recording element substrate 10 in the downstream region of the recording element substrate 10. For this reason, condensation is likely to occur in the downstream region of the recording element substrate 10. In other words, the downstream region of the recording element substrate 10 is a portion (condensation region) that is greatly influenced by the evaporated water 22 (or the influence of condensation). Furthermore, as a result of the inventors' investigations, it was found that when the length of the recording element substrate 10 in the movement direction (conveyance direction) of the recording medium P is x0, the influence of moisture evaporation 22 becomes greater when the substrate length x0 satisfies the following formula:

[0033]

number

[0034] Note that, if the distance between the recording medium P and the recording element substrate 10 is made greater than the thickness of the laminar boundary layer on the recording medium over the entire recording element substrate 10, condensation is less likely to occur on the recording element substrate 10. However, if the distance between the recording medium P and the recording element substrate 10 is increased, it becomes difficult to accurately land the droplets ejected from the ejection ports 13 at the target positions on the recording medium P, resulting in a decrease in the quality of the recorded image. From the viewpoint of landing accuracy, it is not preferable to increase the distance between the recording medium P and the recording element substrate 10.

[0035] In the comparative example of FIG. 5(a), temperature control 24 is performed on the entire ejection port surface 10a of the recording element substrate 10. With this temperature control 24, the entire ejection port surface 10a is heated to approximately 65°C, as shown in FIG. 6(a). Meanwhile, although not shown, the temperature of the recording medium P reaches approximately 75°C. In this case, moisture evaporation 22 from the recording medium P has a large effect on the recording element substrate 10, causing condensation to form on the ejection port surface 10a. In particular, more condensation droplets 23 form in the downstream region of the ejection port surface 10a. In the comparative example of FIG. 5(b), as shown in FIG. 6(b), the entire ejection port surface 10a of the recording element substrate 10 is heated to approximately 75°C by the temperature controller 24. This suppresses the generation of condensation droplets 23, and therefore prevents ejection droplets that rise from the ejection ports 13 during ejection from coming into contact with the condensation droplets 23, and prevents the condensation droplets 23 from penetrating into the ejection ports 13. As a result, ejection defects and image degradation can be suppressed.

[0036] However, the upstream region of the ejection port surface 10a is less affected by the water vapor 22 and is less likely to form condensation. In the comparative example of Figure 5(b), the entire ejection port surface 10a is heated uniformly, and even the region where condensation is less likely to form is heated to approximately 75°C. As a result, a large amount of energy is consumed to suppress condensation. In contrast, in the liquid ejection head 30A of this embodiment shown in Figure 5(c), the ejection port surface 10a is divided into two divided regions 10a-1 and 10a-2, upstream and downstream, as shown in Figure 6(c). The upstream divided region 10a-1 is heated to 65°C by temperature control 24a, and the downstream divided region 10a-2 is heated to 75°C by temperature control 24b. This reduces unnecessary energy consumption and efficiently prevents condensation from forming on the ejection port surface 10a of the recording element substrate 10. 5(c), the ejection port surface 10a of the recording element substrate 10 is divided into two divided regions, an upstream side and a downstream side, but the number of divisions may be three or more. The temperature of each divided region may be appropriately determined taking into consideration the ejection characteristics of the liquid ejection head 30A, the reliability of the liquid, the degree of deterioration in print quality due to condensation caused by long-term continuous printing, and the like.

[0037] The influence of water evaporation 22 and temperature control have been explained above using the recording medium P as an example, but the same can be said for the transfer body 2 shown in FIG. 1. That is, a laminar boundary layer is formed on the transfer body 2 due to water evaporation from the liquid that has landed on the transfer body 2, which is the ejection receiving medium. In each recording head 30, the temperature adjustment means 18 adjusts the temperature of the ejection port surface 10a so that the temperature of the area downstream of the ejection port surface 10a is higher than the temperature of the area upstream of the ejection port surface 10a. This reduces unnecessary energy consumption and makes it possible to efficiently prevent condensation from forming on the ejection port surface 10a of each recording head 30.

[0038] Furthermore, if the printing time is short, the amount of condensation is small, so the impact on image quality is small. However, if printing is continued for a long period of time without performing a recovery operation, the impact of condensation gradually increases. For example, even continuous printing for about five minutes can affect image quality. In the recording device 1 of FIG. 1, a recovery process can be performed during printing. In this recovery process, the carriage 31 is slid and the recovery unit 12 recovers the recording head 30. Since printing cannot be performed during this recovery process, downtime occurs. The downtime associated with performing such a recovery process reduces the productivity of the recorded product P2. According to this embodiment, the impact of condensation on the ejection port surface 10a can be suppressed, thereby reducing the number of recovery processes performed to suppress condensation, and as a result, downtime can be reduced.

[0039] The liquid ejection head 30A or the recording head 30 may be provided with a heating means for heating the recording medium P (transfer body 2) before ejecting the liquid onto the recording medium P. This makes it possible to heat the ejection port surface 10a while heating the recording medium P to an appropriate temperature. The heating means may be a heating element such as a heater, or a heating device that uses IR irradiation (infrared irradiation) or microwave high-frequency induction. The heating means may be provided outside the liquid ejection head 30A or the recording head 30. Furthermore, the ejection port surface 10a includes a condensation region, which is a region where the distance between the ejection port surface 10a and the recording medium P (transfer body 2) is smaller than the thickness of a laminar boundary layer formed on the recording medium P by evaporation of water from the liquid that has landed on the recording medium P. In this case, the temperature adjustment means 18 may adjust the temperature of the condensation region of the ejection port surface 10a so that it is higher than other regions.

[0040] The liquid ejection head 30A may be configured to circulate liquid. FIG. 16 is a schematic diagram showing a configuration for circulating ink supplied to the liquid ejection head. The liquid ejection head 30A is fluidly connected to an ink storage unit 33 that stores ink. Ink is supplied from the ink storage unit 33 to the liquid ejection head 30A. In the recording element substrate 10, ink supplied from the ink storage unit 33 is supplied to each pressure chamber via an internal flow path. In each pressure chamber, a portion of the supplied ink is ejected from the ejection orifice 13. Ink that is not ejected is collected from the pressure chamber via the internal flow path and returned to the ink storage unit 33. In this way, ink can be circulated between the recording element substrate 10 and the ink storage unit 33, making it possible to cool the recording element substrate 10. With this circulation structure, for example, when it is desired to lower the temperature of the recording element substrate 10, the temperature can be lowered more quickly, thereby improving the responsiveness of the temperature control of the recording element substrate 10. It is also possible to collect liquid or foreign matter that has become viscous due to evaporation from the discharge port 13, and to suppress the increase in viscosity of the liquid that occurs in the discharge port 13 or the pressure chamber.

[0041] It is also possible to provide an ink storage section 33 on each of the ink supply side and ink recovery side of the liquid ejection head 30A. In this case, ink is supplied from the ink storage section 33 on the supply side to the liquid ejection head 30A, and ink is recovered from the liquid ejection head 30A to the ink storage section 33 on the recovery side. This configuration also allows the ink in the pressure chamber to flow, thereby achieving the same effect as the circulation structure described above.

[0042] (Variation) It is also possible to produce a recorded product by using the liquid ejection head 30A to draw a liquid image directly on the recording medium P on the platen without using the transfer body 2. In this case, the temperature-controlling heater 15 shown in FIG. 14 may be provided on the platen that supports the recording medium P. 15 is an explanatory diagram of a platen 17 equipped with a temperature-adjustable heater 15. Fig. 15(a) shows the positional relationship between the liquid ejection head 30C and the platen 17. Fig. 15(b) shows the arrangement of the temperature-adjustable heater 15 provided on the platen 17. 15(a), the platen 17 is disposed at a position facing the liquid ejection head 30C and supports the recording medium P. The recording medium P is transported so as to pass between the liquid ejection head 30C and the platen 17. The liquid ejection head 30C is equipped with a recording element substrate 10 in which the temperature control heater 15 has been removed from the configuration shown in FIG. 14, and liquid is ejected from each ejection port 13 of the recording element substrate 10 toward the recording medium P.

[0043] As shown in FIG. 15(b), a plurality of temperature-controlled heaters 15 are provided on the surface of the platen 17 facing the recording element substrate 10. Each temperature-controlled heater 15 is arranged so as to correspond one-to-one with the temperature sensor 14 in each adjustment area 11 of the recording element substrate 10. The temperature-controlled heater 15 is driven in response to the detection value of the corresponding temperature sensor 14. In this case, as in the example of FIG. 14, each adjustment area 11 can be set to a temperature in accordance with a threshold value. For example, the temperature control unit 18 can control the temperature so that the temperature of the downstream area of ​​the recording element substrate 10 is higher than the temperature of the upstream area in the movement direction of the recording medium P.

[0044] (Second embodiment) In the first embodiment, the temperature of the downstream region of the ejection port surface 10a of the recording element substrate 10 is set high in each recording head 30. In contrast, in the recording device according to the second embodiment of the present invention, the temperature is adjusted for each recording head. 8 is a schematic diagram showing the configuration of a recording apparatus according to a second embodiment of the present invention. Five recording heads 30 are arranged in parallel from upstream to downstream in the transport direction of the recording medium P, and each recording head 30 ejects liquid onto the moving recording medium P. The number of recording heads 30 is not limited to five; the number of recording heads 30 may be two or more.

[0045] Each print head 30 has a structure similar to the liquid ejection head 30A described in the first embodiment, but the temperature adjustment means 18 can individually adjust the temperature of the ejection port surface 10a of each print head 30. In this embodiment, the temperature adjustment means 18 includes a temperature sensor 14 and a temperature adjustment heater 15 for each print head 30, and is configured to uniformly heat the entire ejection port surface 10a of the printing element substrate 10 in each print head 30. The temperature adjustment means 18 adjusts the temperature of the ejection port surface 10a of the print head 30 so that it becomes higher the further downstream.

[0046] In the recording device of this embodiment, as the recording medium P passes successively past each recording head 30, the amount of liquid 21b that lands on the recording medium P (adhered amount) increases the further downstream in the direction of movement of the recording medium P, and therefore the amount of water evaporation increases the further downstream. As a result, condensation is more likely to occur on the ejection port surfaces 10a of the recording heads 30 the further downstream. In this embodiment, by increasing the temperature of the ejection port surfaces 10a of the recording heads 30 the further downstream, unnecessary energy consumption can be reduced and condensation can be efficiently suppressed across all of the recording heads 30 arranged in parallel. Furthermore, by making the temperature of the ejection port surface 10a of the downstream recording head 30 higher than the temperature of the ejection port surface 10a of the upstream recording head 30, it is possible to suppress deterioration of print quality due to condensation.

[0047] (Third embodiment) FIG. 9 is a schematic diagram showing the configuration of a recording device according to a third embodiment of the present invention. The recording device produces a recorded product by directly drawing a liquid image on a recording medium P, and includes multiple recording heads 30, a heating means 50, and a transport mechanism 80 as a moving means. The transport mechanism 80 continuously transports the recording medium P. Five recording heads 30 are arranged in parallel from upstream to downstream in the transport direction of the recording medium P, and each recording head 30 ejects liquid onto the moving recording medium P. Each recording head 30 is the same as that described in the second embodiment. The number of recording heads 30 may be two or more. The heating means 50 is located upstream of each recording head 30, and heats the recording medium P before the liquid is ejected onto the recording medium P. As the heating means 50, a heating element such as a heater, or a heating device using IR irradiation (infrared irradiation) or high-frequency induction of microwaves can be used.

[0048] In the recording device of this embodiment, as in the second embodiment, the amount of liquid 21b that lands on the recording medium P (adhered amount) increases as the recording medium P is transported downstream, and condensation is therefore more likely to occur on the ejection port surface 10a of the recording head 30 the further downstream. The temperature adjustment means 18 adjusts the temperature of the ejection port surface 10a of the recording head 30 so that it is higher the further downstream. This reduces unnecessary energy consumption and efficiently prevents condensation across all of the recording heads 30 arranged in parallel.

[0049] (Fourth embodiment) 10A and 10B are schematic diagrams showing the configuration of a recording apparatus according to a fourth embodiment of the present invention, in which Fig. 10A shows the recording head moving forward, and Fig. 10B shows the recording head moving backward. The recording device shown in FIG. 10 is a serial head type and includes a carriage 40 carrying a recording head 30. A platen 51 supports a recording medium P. The carriage 40 can move back and forth on the platen 51 in a direction intersecting or perpendicular to the transport direction of the recording medium P. With the recording medium P stationary on the platen 51, the recording head 30 ejects liquid toward the recording medium P as the carriage 40 moves back and forth. The carriage 40 constitutes a moving device that moves the recording head 30 and the recording medium P relative to each other. Below, downstream and upstream are defined with respect to the relative movement direction of the recording medium P when viewed from the recording head 30. For example, in the forward path shown in FIG. 10(a), the recording head 30 moves leftward in the drawing, but when viewed from the moving recording head 30, the recording medium P appears to move rightward. In this case, the right side in the drawing is downstream. For the same reason, in the return path shown in FIG. 10(b), the left side in the drawing is downstream.

[0050] The recording head 30 has a structure similar to that of the liquid ejection head 30A described in the first embodiment, but the temperature adjustment control of the temperature adjustment unit 18 differs from that of the first embodiment. The temperature adjustment unit 18 switches the downstream region of the ejection port surface 10a between the outbound and return paths of the carriage 40. Note that in the example shown in FIG. 14, the ejection port arrays 8 were arranged in parallel from upstream to downstream with respect to the transport direction of the recording medium, but here, the ejection port arrays 8 are arranged in parallel from upstream to downstream with respect to the movement direction of the carriage 40. Also, in this embodiment, the aforementioned substrate length X0 indicates the length of the recording element substrate 10 in the movement direction of the carriage 40. 10(a), when the carriage 40 moves on the forward path, based on the above definition, the right side of the recording element substrate 10 is downstream as viewed in the drawing. In this case, the right side of the recording element substrate 10 is more susceptible to moisture evaporation, making condensation more likely to occur. For this reason, during the forward path, the temperature adjustment unit 18 adjusts the temperature so that the temperature in the right region (downstream) of the recording element substrate 10 is higher than that in the left region (upstream) of the recording element substrate 10.

[0051] 10(b), when the carriage 40 moves on the return path, the left side of the recording element substrate 10 as viewed in the drawing is downstream in the relative movement direction of the recording medium P. In this case, the effect of moisture evaporation is large on the left side of the recording element substrate 10, making condensation more likely to occur. For this reason, during the return path, the temperature adjustment unit 18 adjusts the temperature so that the temperature in the left region (downstream) of the recording element substrate 10 is higher than that in the right region (upstream) of the recording element substrate 10. As described above, by switching the temperature control between the outbound and return routes, unnecessary energy consumption can be reduced and condensation can be efficiently suppressed. In this embodiment, the platen 51 may also have a heating means. In this case, the platen 51 heats the recording medium P supported in a stationary state. This makes it possible to heat the recording medium P before the liquid is applied. As the heating means, a heating element such as a heater, or a heating device using IR irradiation (infrared irradiation) or high-frequency induction of microwaves can be used.

[0052] (Fifth embodiment) 11A and 11B are schematic diagrams showing the configuration of a recording apparatus according to a fifth embodiment of the present invention, in which Fig. 11A shows the state in which the recording head is moving forward, and Fig. 11B shows the state in which the recording head is moving backward. The recording apparatus of this embodiment differs from the recording apparatus of the fourth embodiment in that it has a first heating unit 50a and a second heating unit 50b. The configuration other than these heating units 50a and 50b is the same as that described in the fourth embodiment, so a description thereof will be omitted here. For convenience, the carriage 40 is omitted from FIG. 11.

[0053] The recording head 30 has a first heating section 50a and a second heating section 50b. The first heating section 50a is located upstream of the ejection port surface 10a in the direction of relative movement of the recording medium P during the forward path of the carriage 40. The second heating section 50b is located upstream of the ejection port surface 10a in the direction of relative movement of the recording medium P during the return path of the carriage 40. When the carriage 40 moves on the forward path, the first heating section 50a heats the recording medium P. When the carriage 40 moves on the return path, the second heating section 50b heats the recording medium P. Specifically, on the outbound path, as shown in Fig. 11(a), the first heating section 50a heats the recording medium P. At this time, the temperature adjustment means 18 adjusts the temperature so that the temperature in the right-hand region (downstream) of the recording element substrate 10 is higher than that in the left-hand region (upstream) of the recording element substrate 10. On the other hand, on the return path, as shown in Fig. 11(b), the second heating section 50b heats the recording medium P. At this time, the temperature adjustment means 18 adjusts the temperature so that the temperature in the left-hand region (downstream) of the recording element substrate 10 is higher than that in the right-hand region (upstream) of the recording element substrate 10.

[0054] In addition to the effects described in the fourth embodiment, the recording apparatus of this embodiment has the following effects. In the fourth embodiment, the platen 51 uniformly heats the entire recording medium P. In contrast, in the present embodiment, the first heating section 50a and the second heating section 50b move and heat the recording medium P immediately before printing. In this case, since it is not necessary to heat the entire recording medium at the same time, the power consumption required for heating can be reduced, and the recording medium P can be heated efficiently. Furthermore, in the fourth embodiment, since it is necessary to arrange a heating means such as a heater in an area that covers the entire recording medium P, the heating means becomes larger as the size of the recording medium P increases. In contrast, in the present embodiment, it is not necessary to heat the entire recording medium at the same time, so it is possible to reduce the size of the means for heating the recording medium P.

[0055] The circulation structure described in the first embodiment may be applied to the second to fifth embodiments described above. In particular, the circulation structure is more preferable in the fourth and fifth embodiments because it allows the temperature of the region to be controlled to a low temperature to be lowered more quickly when switching the temperature control between the forward and backward paths. [Explanation of symbols]

[0056] 10. Recording element board 10a Discharge port surface 30A liquid ejection head P Recording medium

Claims

1. an ejection port surface on which a plurality of ejection ports are arranged; a temperature control means for adjusting the temperature of the ejection port surface by dividing the ejection port surface into a plurality of adjustment areas, the temperature control means including a temperature sensor for detecting a temperature in each adjustment area and a temperature control heater for heating the adjustment area; A liquid ejection head having a recording element substrate including: the ejection openings of the recording element substrate eject liquid onto an ejection receiving medium that moves relatively to the liquid ejection head; The temperature control means is capable of individually adjusting the temperatures of the multiple adjustment areas, and by driving the temperature control heater based on the detection value of the temperature sensor, adjusts the temperature of the ejection port surface so that the temperature of the downstream area of ​​the ejection port surface is higher than the temperature of the upstream area of ​​the ejection port surface in the relative movement direction of the ejection medium when viewed from the liquid ejection head.

2. 2. The liquid ejection head according to claim 1, wherein the recording element substrate has a heat generating element for each ejection port that generates thermal energy for ejecting liquid from the ejection port, and the heat generating element is used to adjust the temperature of the ejection port surface.

3. A liquid ejection head as described in claim 1 or 2, wherein in the downstream region of the ejection outlet surface, the thickness of a laminar boundary layer formed on the ejection medium by evaporation of water from the liquid that has landed on the ejection medium is greater than the distance between the ejection medium and the ejection outlet surface.

4. The length of the recording element substrate in the relative movement direction of the ejection receiving medium is x0 (mm), the height from the ejection receiving medium to the recording element substrate is h (mm), the movement speed of the ejection receiving medium is U0 (m / s), and the kinetic viscosity of air is ν (m 2 / s), the length x0 of the recording element substrate is x0>0.0333×h 2 ×U0 / ν 4. The liquid ejection head according to claim 3, wherein:

5. A recording element substrate having an ejection port surface on which a plurality of ejection ports are arranged; a temperature control means for adjusting the temperature of the ejection port surface; A liquid ejection head having the ejection openings of the recording element substrate eject liquid onto an ejection receiving medium that moves relatively to the liquid ejection head; the temperature adjustment unit adjusts the temperature of the ejection port surface so that the temperature of a downstream region of the ejection port surface is higher than the temperature of an upstream region of the ejection port surface in a relative movement direction of the ejection receiving medium when the ejection receiving medium is viewed from the liquid ejection head; in the downstream region of the ejection port surface, the thickness of a laminar boundary layer formed on the ejection receiving medium by water evaporation from the liquid that has landed on the ejection receiving medium is greater than the distance between the ejection receiving medium and the ejection port surface, When the length of the recording element substrate in the relative movement direction of the ejection receiving medium is x0 (mm), the height from the ejection receiving medium to the recording element substrate is h (mm), the movement speed of the ejection receiving medium is U0 (m / s), and the kinetic viscosity of air is ν (m 2 / s), the length x0 of the recording element substrate is x0>0.0333×h2×U0 / ν That is, a liquid ejection head.

6. The liquid ejection head according to claim 1 , further comprising a heating unit that heats the ejection receiving medium before the liquid is ejected onto the ejection receiving medium.

7. the relative movement direction of the ejection receiving medium includes a first direction and a second direction opposite to the first direction, The liquid ejection head according to claim 1 , wherein the temperature control unit switches the downstream region of the ejection port surface between the first direction and the second direction.

8. The liquid ejection head according to claim 1 , wherein a plurality of the recording element substrates are arranged across the entire printable area in the width direction of the ejection receiving medium.

9. 7. The liquid ejection head according to claim 1, wherein the ejection medium is a transfer body that temporarily holds an intermediate image to be transferred, and the ejection opening ejects the liquid toward the transfer body to form the intermediate image.

10. A liquid ejection head as described in any one of claims 1 to 9, configured to allow the liquid to circulate between the liquid ejection head and the outside.

11. A liquid ejection head according to any one of claims 1 to 10; a moving means for moving the liquid ejection head and the ejection receiving medium relative to each other; A liquid ejection device comprising:

12. a reservoir that contains a liquid to be supplied to the recording element substrate; The liquid ejection device according to claim 11 , wherein the liquid is configured to be circulatable between the recording element substrate and the container.

13. a plurality of liquid ejection heads each having an ejection port surface on which a plurality of ejection ports are arranged, each ejection port ejecting liquid onto a moving ejection receiving medium; a temperature adjusting unit that adjusts the temperature of the ejection port surface of each of the plurality of liquid ejection heads individually; the plurality of liquid ejection heads are arranged in parallel from upstream to downstream in the direction of movement of the ejection receiving medium, The liquid ejection apparatus according to claim 1, wherein the temperature adjusting means provided in each of the plurality of liquid ejection heads adjusts the temperature of the ejection port surface of the liquid ejection head so that the temperature increases toward the downstream side.

14. The liquid ejection device according to claim 13 , wherein the ejection receiving medium is a transfer body that temporarily holds an intermediate image to be transferred, and a recorded product is produced by transferring the image made of the liquid via the transfer body.

15. a transport mechanism that transports the ejection receiving medium; The liquid ejection device according to claim 13 , further comprising: a heating unit that heats the ejection receiving medium, the heating unit being located upstream of the plurality of liquid ejection heads in the transport direction of the ejection receiving medium.

16. A liquid ejection device described in any one of claims 13 to 15, wherein in the downstream region of the ejection outlet surface of each of the liquid ejection heads, the thickness of the laminar boundary layer formed on the ejected medium by evaporation of water from the liquid that has landed on the ejected medium is greater than the distance between the ejected medium and the ejection outlet surface.

17. Each of the liquid ejection heads has a recording element substrate equipped with the ejection port surface, In each of the liquid ejection heads, when the length of the recording element substrate in the direction of relative movement of the ejection receiving medium with respect to the liquid ejection head is x0 (mm), the height from the ejection receiving medium to the recording element substrate is h (mm), the moving speed of the ejection receiving medium is U0 (m / s), and the kinetic viscosity of air is ν (m 2 / s), the length x0 of the recording element substrate is x0>0.0333×h2×U0 / ν The liquid ejection device according to claim 16, wherein

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