JP2017114123A - Drying device and liquid discharge device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance productivity of printing and attain space saving of a device body by shortening a conveyance passage length of a recording medium to be required for drying.SOLUTION: A drying device dries ink which is discharged from droplet discharge heads 21 to 25 and is coated on a medium P. The drying device includes: a primary drying mechanism 20A which heats the medium P conveyed to face the droplet discharge heads 21 to 25 while sucking the medium; a secondary drying mechanism 20B which is arranged on a conveyance direction downstream side of the medium P in the primary drying mechanism 20A, suspends the medium P in a U-shape, and blows warm air to an ink coating surface of the medium P suspended in the U-shape; and a control section which controls the primary drying mechanism 20A and the secondary drying mechanism 20B.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a drying device and a liquid ejection device.

  2. Description of the Related Art Conventionally, line inkjet printing apparatuses are known that involve a step of applying ink to a recording medium (hereinafter referred to as “medium”) and then drying it.

  In a conventional line ink jet printing apparatus, particularly when printing is performed on a medium penetrating water-based ink, there is a problem that moisture in the ink penetrates the base paper layer of the medium and causes “bleeding”. Therefore, the line inkjet printing apparatus needs to dry the printing surface instantaneously in order to prevent the occurrence of bleeding.

  Further, even when the medium is impermeable, in order to prevent overflow of ink (bleeding), drying similar to the above is important in the line inkjet printing apparatus.

  In a conventional line inkjet printing apparatus, the printing surface is dried by spraying warm air after applying ink. However, the conventional line inkjet printing apparatus has a problem that a large amount of wind speed and temperature are required to dry in a short time. For this reason, the conventional line inkjet printing apparatus employs a method of extending the drying time, but there are problems that the productivity is low and the path of the media becomes long, leading to an increase in the size of the apparatus.

  By the way, as the above-described conventional line inkjet printing apparatus, there is one having a configuration disclosed in Patent Document 1 under the name “inkjet printer”.

  The ink jet printer disclosed in Patent Document 1 is provided with a drying unit that blows warm air toward a medium on a platen roller on the downstream side in the medium conveyance direction. The drying means is configured such that the hot air blowing direction from the hot air blowing port is inclined toward the recording paper feeding direction.

  With the above-described configuration, the warm air from the drying means is less likely to reach the vicinity of the nozzles of the inkjet head, and the ink droplet ejection direction is not disturbed by the influence of the warm air. However, according to the ink jet printer disclosed in Patent Document 1, the effect of increasing the efficiency of drying is small, and therefore it cannot cope with high productivity.

  Accordingly, the present invention has been made in view of the above, and is a drying device that can improve the productivity of printing and reduce the transport path length of the recording medium required for drying, thereby saving the space of the apparatus main body. And it aims at provision of a liquid discharge device.

  In order to solve the above-described problems and achieve the object, the present invention is directed to a drying apparatus that dries ink on a recording medium that has been ejected and applied from a droplet ejection head, facing the droplet ejection head. A primary drying mechanism that heats the recording medium to be conveyed while sucking, and a recording medium that is disposed downstream of the primary drying mechanism in the conveyance direction of the recording medium, and suspends the recording medium in a U-shape. A secondary drying mechanism that blows warm air toward the ink application surface of the recording medium suspended in a shape, and a controller that controls the primary drying mechanism and the secondary drying mechanism. Features.

  According to the present invention, it is possible to increase the productivity of printing and to shorten the transport path length of the recording medium required for drying, thereby saving the space of the apparatus main body.

FIG. 1 is a front view illustrating a schematic configuration of the inkjet printer according to the first embodiment. FIG. 2 is a block diagram illustrating a hardware configuration of the inkjet printer. FIG. 3 is an enlarged perspective view showing a pair of heating units forming a part of the drying apparatus. FIG. 4 is a graph showing the relationship between the hot air blowing speed by the hot air blowing section and the suction pressure by the pair of heating sections. FIG. 5 is a diagram schematically showing an image forming process from application of ink to drying on a medium. FIG. 6 is a front view showing a schematic configuration of the ink jet printer according to the third embodiment. FIG. 7 is a block diagram illustrating a hardware configuration of the inkjet printer.

  Hereinafter, embodiments of a drying device and a liquid discharge device will be described in detail with reference to the accompanying drawings.

(First embodiment)
Here, FIG. 1 is a front view showing a schematic configuration of the inkjet printer 1 according to the first embodiment, FIG. 2 is a block diagram showing a hardware configuration of the inkjet printer 1, and FIG. 3 is a part of the drying apparatus A. FIG. 3 is an enlarged perspective view showing a pair of heating units 28 in an enlarged manner.

  The ink jet printer 1 according to the first embodiment shown in FIG. 1 is a liquid ejection device. The ink jet printer 1 discharges and applies water-based ink onto the medium P from droplet discharge heads 21 to 25 described later by an ink jet method. The medium P is a non-penetrating medium that does not penetrate water-based ink.

  As shown in FIG. 1, the inkjet printer 1 transports a medium P through a feeding unit 10, a drying apparatus A, a media transport roller 30 that is a transport unit, and a winding unit 40 that winds up a medium P on which an image is fixed. The arrangement is in order from the upstream side toward the downstream side in the direction α.

  The drying apparatus A includes a plurality of drying units 20 that dries ink discharged from droplet discharge heads 21 to 25 described later and applied to the medium P.

  As shown in FIG. 2, the feeding unit 10, the plurality of drying units 20 constituting the drying apparatus A, the droplet discharge heads 21 to 25, the media transport roller 30 and the winding unit 40 are connected to the control unit 70. The drive is appropriately controlled. The control unit 70 causes a CPU (Central Processing Unit) to execute software (program), that is, may be realized by software (program), or may be realized by hardware such as an IC (Integrated Circuit). The software (program) and hardware may be used in combination.

  The feeding unit 10 includes a roll unit 11 in which the medium P is wound in a roll shape, a pre-coating unit 12 for applying a pre-coating liquid to the medium P fed from the roll unit 11, and a pre-coating liquid. A pre-coating drying device 13 for drying is provided.

  The “priming liquid” has an effect of improving the cohesiveness of the pigment in the ink and improving the retention of the pigment on the surface of the medium P and bleeding.

  In the feeding unit 10 described above, after the pre-coating liquid is applied to the medium P by the pre-coating application unit 12, the pre-coating liquid is dried by the pre-coating drying device 13.

  On the downstream side in the transport direction α of the feeding unit 10 described above, droplet discharge heads 21 to 25 configured by a line head that discharges ink onto the medium P and forms an image include black K, cyan C, and magenta. M, yellow Y, and white W ink are arranged in order.

  Each of the above-described droplet discharge heads 21 to 25 determines the application position with high accuracy by discharging ink in synchronization with an encoder 31 that detects a rotation speed provided on a media transport roller 30 described later. .

  The drying unit 20 shown in the present embodiment is disposed for each of the droplet discharge heads 21 to 25, and includes a primary drying mechanism 20A and a secondary drying mechanism 20B for drying the ink applied to the medium P. have.

  The primary drying mechanism 20 </ b> A heats the medium P conveyed while being opposed to the droplet discharge heads 21 to 25 while sucking. The primary drying mechanism 20 </ b> A maintains the gap between the droplet discharge heads 21 to 25 and the medium P by sucking the medium P. That is, the primary drying mechanism 20A separates the droplet discharge heads 21 to 25 from the medium P. The gap between the heads 21 to 25 and the medium P is about 1 mm.

  The control unit 70 of the ink jet printer 1 of the present embodiment sets the heating temperature of the medium P by the primary drying mechanism 20A within a range of 40 ° C. to 80 ° C. when the conveyance speed of the medium P is 30 to 50 m / min. .

  The primary drying mechanism 20 </ b> A includes a pair of transport guides 16 that guide the media P to be transported, and a suction unit 27 that includes a heater 26, a fan, and the like disposed between the pair of transport guides 16.

  The pair of transport guides 16 are arranged in the vicinity of each upper end portion of the heating unit 28 described below at a predetermined interval for each of the droplet discharge heads 21 to 25. With this configuration, the primary drying mechanism 20A is configured to heat and dry the medium P guided by the pair of conveyance guides 16 while being sucked by the suction unit 27 from the lower surface (back surface) side of the medium P. Yes.

  The secondary drying mechanism 20B is arranged in the drying unit 20 on the downstream side in the transport direction of the medium P of the primary drying mechanism 20A described above. The secondary drying mechanism 20 </ b> B includes a warm air blowing unit 50 that blows warm air on the medium P to be transported and a pair of heating units 28 that heat the medium P to be transported.

  The medium P is suspended in a U shape between the conveyance guides 16 corresponding to the droplet discharge heads 21 to 25 having different colors. In the following, the portion suspended in the U-shape is referred to as a “U-shape portion”.

  The pair of heating units 28 shown in the present embodiment has a function as a suction unit that sucks the upstream portion Pa and the downstream portion Pb on the outer surface side (ink non-application surface) of the U-shaped portion of the medium P. doing. The pair of heating units 28 are arranged to face each other on both sides of the U-shaped portion of the medium P. In other words, the secondary drying mechanism 20B is provided with a pair of heating units 28 that also serve as a suction unit, facing both sides of the outer surface side (ink non-application surface) of the U-shaped portion of the medium P.

  The pair of heating units 28 also serving as a suction unit has a suction mechanism 28a such as a fan disposed on the inner side facing the lower surface (back surface) of the U-shaped portion of the medium P, and a heating mechanism 28b such as a heater disposed on the outer side. .

  The hot air blowing unit 50 is provided in a pair with a predetermined interval between the pair of heating units 28 described above. The hot air blowing unit 50 blows hot air toward the ink application surface Pd of the U-shaped portion of the medium P.

  The hot air blowing unit 50 includes a casing 51 formed in a vertically long rectangular parallelepiped shape as shown in FIG. A large number of spray holes 52 for spraying warm air uniformly on the ink application surface Pd of the medium P are formed at predetermined intervals on both side wall surfaces 51a and 51b of the casing 51 facing the U-shaped portion of the medium P. It is arranged. In addition, the arrow a has shown the blowing direction of warm air.

  The hot air blowing unit 50 includes a plurality of introducing portions 53 for introducing outside air through the intake passage b on the upper wall surface 51 c of the housing 51. A fan for pressurizing the introduced outside air and a heater 54 for heating the outside air are disposed in the introduction portion 53 of the hot air blowing unit 50. The hot air blowing unit 50 generates hot air having a predetermined temperature by the heater 54 in the introduction unit 53.

  By the way, the control unit 70 of the ink jet printer 1 uses the hot air blown from the above-described hot air spraying unit 50 to the medium P when the conveyance speed of the medium P is 30 to 50 m / min, on the ink application surface Pd of the medium P. The wind speed is set to 10 m / sec or more, and the temperature of the medium P is set to 60 ° C to 100 ° C.

  In the present embodiment, the control unit 70 controls the suction pressure of each of the pair of heating units 28 to be larger than the hot air blowing pressure by the hot air blowing unit 50. As a result, it is possible to prevent fluttering due to the hot air being applied to the medium P in an area where the pair of heating units 28 does not exist, and to ensure the stability of the U-shaped portion of the medium P described above.

  Furthermore, the control unit 70 controls the difference between the dynamic air pressure in the hot air blowing unit 50 and the suction pressure in the pair of heating units 28 to be approximately 5 kPa or less. In this case, considering the error of 0.5 kPa, the difference between the dynamic pressure of the hot air and the suction pressure may be 4 to 6 kPa. Thereby, it is possible to prevent the locked state of the media P that leads to poor conveyance due to friction.

  In [Table 1] and [Table 2], hot air blowing speed (m / s), dynamic pressure (Pa), dynamic pressure (Kpa), suction pressure (Kpa), pressure, media in a region other than the heating unit 28 The relationship between flapping of P and transport lock of media P is shown.

“Dynamic pressure” refers to the pressure that exists in the direction of flow depending on the flow velocity of air. The dynamic pressure is an increase in kinetic energy due to the flow velocity, and can be expressed by the following equation.
Pv = ρ / 2 · V ² (Pa)
V: Wind speed (m / s) ρ: Air density (Kg / m ³ )

  [Table 1] shows the relationship when the transport speed of the media P is 50 m / min, and [Table 2] shows the relationship when the transport speed of the media P is 30 m / min.

  As shown in [Table 1] and [Table 2], the press per unit time decreases as the transport speed of the media P decreases, and the press per unit time increases as the transport speed of the media P increases. . This is because, when the conveyance speed of the medium P is high, the medium P is lifted (fluttering) unless the pressure per unit time is increased.

  Moreover, if the conveyance speed of the medium P becomes slow, the medium P will be adsorbed and locked unless the press per unit time is made low. Or even if it does not lock, if the conveyance speed of the media P becomes slow, there is a problem that the image shrinks. However, if the conveyance speed of the medium P becomes slow, the medium P can be dried for a long time.

  FIG. 4 is a graph showing the relationship between the hot air blowing speed by the hot air blowing section 50 and the suction pressure by the pair of heating sections 28. As shown in FIG. 4, as the warm air blowing speed increases, the suction pressure by the pair of heating units 28 that also serve as the suction unit is reduced.

  The medium P is transported by the media transport roller 30 while keeping the transport speed constant under the control of the control unit 70. Here, since the inkjet printer 1 applies a load to the medium P by the suction unit 27 of the primary drying mechanism 20A and the pair of heating units 28 of the secondary drying mechanism 20B, the medium P does not float and the medium P is not lifted. The U-shaped portion is stably formed and held. That is, the U-shaped portion of the medium P described above has a stable shape due to the hot air blowing unit 50 and the pair of heating units 28, and does not adversely affect the transportability.

  Here, FIG. 5 is a diagram schematically showing an image forming process from application of ink on the medium P to drying. Immediately after the ink 60 is applied to the medium P shown in FIG. 5A, the hot air is blown by the hot air blowing unit 50 of the secondary drying mechanism 20B, whereby the ink 60 ( On the ink application surface Pd), the dots are enlarged and the heating from the medium P becomes easy. The reason why the dots of the ink 60 are enlarged is that when the secondary drying mechanism 20B is heated, the surface active agent contained in the ink 60 disappears and the wettability is improved.

  Further, when warm air is blown by the warm air blowing unit 50 of the secondary drying mechanism 20B, as shown in FIG. 5B, the ink 60 (ink-applied surface Pd) applied on the medium P becomes a pigment. This produces an aggregating action. More specifically, when heated by the secondary drying mechanism 20B, the ink 60 (ink application surface Pd) applied on the medium P evaporates water, and the pigment is set on the medium P by thickening. At this time, the organic solvent in the ink 60 having a high concentration dissolves the surface of the pre-applying liquid of the medium P, thereby improving the fixability of the pigment.

  Further, when hot air is blown by the hot air blowing unit 50 of the secondary drying mechanism 20B, the organic solvent in the ink 60 is evaporated and a resin film 61 is formed as shown in FIG. 5C.

  According to the inkjet printer 1 of the present embodiment, for example, when the conveyance speed of the medium P is 50 m / min, the air velocity on the medium P by the warm air blowing unit 50 of the secondary drying mechanism 20B is set to 10 m / sec. When the ink application surface Pd of the medium P is heated in the range of 60 ° C. to 100 ° C., a drying effect is obtained. Further, according to the inkjet printer 1 of the present embodiment, for example, when the medium P is heated in the range of 40 ° C. to 80 ° C. by the primary drying mechanism 20A when the conveyance speed of the medium P is 50 m / min, the drying effect is obtained. Is obtained. Moreover, according to the inkjet printer 1 of this embodiment, the efficiency is good by setting the air speed on the medium P of the hot air by the hot air blowing unit 50 of the secondary drying mechanism 20B in the range of 10 to 30 m / sec. Drying performance is obtained.

  According to the ink jet printer 1 according to the first embodiment described in detail above, high-quality image formation can be performed with high production regardless of permeable media or non-permeable media.

  The medium P described above is heated while being adsorbed by the pair of heating portions 28 on both the upstream side portion Pa and the downstream side portion Pb on the outer surface side (ink non-application surface) of the U-shaped portion. Since this has the same configuration as the primary drying mechanism 20A, it has the effect of promoting ink drying.

The media transport roller 30 is disposed on the downstream side of the drying apparatus A having the plurality of drying units 20 described above. The media transport roller 30 has a fixing unit 32 that reliably fixes ink to the media P. The relationship between the conveyance speed of the medium P of the medium conveyance roller 30 and the conveyance speed of the medium P of the roll unit 11 of the feeding unit 10 is as follows because the U-shaped portion of the medium P is stably formed. It has become a relationship.
Conveying speed of media conveying roller 30 ≦ conveying speed of roll unit 11 of feeding unit 10

  In the present embodiment, the inkjet printer 1 is provided with a distance measuring sensor S in the vicinity of the lower end portion Pc of the U-shaped portion of the medium P in order to stably maintain the U-shaped portion of the medium P. The distance measuring sensor S measures the distance to the lower end part Pc of the U-shaped part of the medium P. The distance measuring sensor S is connected to the input side of the control unit 70 described above. The controller 70 feeds back the distance to the lower end portion Pc of the U-shaped portion of the media P measured by the distance measuring sensor S to the rotational speed of the media transport roller 30.

  That is, when the distance measured by the distance measuring sensor S is shorter than a predetermined value, the control unit 70 of the ink jet printer 1 means that the U-shaped portion of the medium P is extended. To speed up. On the other hand, when the distance measured by the distance measuring sensor S is longer than a predetermined value, the control unit 70 of the inkjet printer 1 means that the U-shaped portion of the medium P is contracted. To slow down. Thereby, the control unit 70 of the ink jet printer 1 performs control so that the hanging length of the U-shaped portion of the medium P is constant.

  By the way, in this embodiment, the ink discharged from the droplet discharge heads 21 to 25 is water-based ink that can be printed on the medium P that is a non-penetrable medium. This water-based ink contains a resin. The water-based ink resin is dissolved by heating to form a film. The ink jet printer 1 performs printing by fixing the pigment contained in the water-based ink to the medium P. For this reason, as is well known, a primary drying mechanism 20A for heating the medium P in advance during printing is required. Then, the media P in which the applied ink is not completely dried is transported to the secondary drying mechanism 20B and dried.

  According to the inkjet printer 1 according to the first embodiment described above, the following effects can be obtained.

  Since the inkjet printer 1 includes the primary drying mechanism 20A and the secondary drying mechanism 20B, the drying efficiency can be increased and the printing productivity can be increased. Further, the ink jet printer 1 can shorten the path (conveyance path length) of the medium P required for drying, and can realize space saving of the printer body.

  Furthermore, when the U-shaped portion of the media P is blown to the U-shaped portion of the media P by the pair of heating units 28 in a state where the U-shaped portion of the media P is not sucked and guided from the outside, the stability of the U-shaped portion of the media P is lost. P goes wild. Accordingly, the inkjet printer 1 can hold the formation while stabilizing the shape of the U-shaped portion of the medium P by sucking and holding the U-shaped portion of the media P from the outside by the pair of heating units 28 that also serve as the suction unit. it can.

  In addition, since the inkjet printer 1 can stabilize the U-shaped portion of the media P by disposing the pair of heating units 28 that also serve as the suction unit described above, the lower end portion Pc of the U-shaped portion of the media P is stabilized. It becomes possible to delete the conveyance roller arranged in the. As a result, the ink jet printer 1 does not transfer (block) the ink to the transport roller that contacts the ink application surface of the medium P.

  Further, the ink jet printer 1 can apply a load to the medium P by sucking the medium P by the pair of heating units 28 that also serve as a suction unit, and can prevent the floating and tension the medium P. Furthermore, the inkjet printer 1 can improve the drying property by heating the medium P simultaneously with the suction by the pair of heating units 28 that also serve as the suction unit.

  Furthermore, the inkjet printer 1 can obtain a higher drying effect by clarifying the temperature range on the medium P due to the heating of the primary drying mechanism 20A. Furthermore, the ink jet printer 1 can also obtain a higher drying effect by clarifying the wind speed and temperature range on the medium P due to the heating of the secondary drying mechanism 20B.

  That is, according to the inkjet printer 1, the ink ejection reliability of the droplet ejection heads 21 to 25 by drying and heating can be ensured while maintaining the space saving and the drying performance of the printer main body, and the droplet ejection head 21 for each color. Since the temperature of the medium P on which ~ 25 ink is deposited can be kept constant, stable image quality can be obtained over time.

  In the above-described embodiment, the pair of heating units 28 described above have a configuration that also has a function as a suction unit that sucks the upstream portion Pa and the downstream portion Pb of the U-shaped portion of the medium P. Although illustrated, it is not restricted to this structure, You may arrange | position a pair of heating part 28 and a suction part separately. Moreover, it can be set as the structure which replaced a pair of heating part 28 of 20 A of primary drying mechanisms, and the secondary drying mechanism 20B. Also in this case, the same effect as the above-described embodiment can be obtained.

(Second Embodiment)
Next, a second embodiment will be described. In addition, the same part as 1st Embodiment mentioned above is shown with the same code | symbol, and description is also abbreviate | omitted.

  According to the image forming process from ink application to drying on the medium P described in the first embodiment, if the temperature of the medium P is different, the image quality is also different. It is necessary for obtaining a stable image to be constant.

  Since the gap between the droplet discharge heads 21 to 25 and the medium P is as small as about 1 mm as described above, the droplet discharge heads 21 to 25 are heated by the heat of the medium P. Therefore, in the conventional ink jet printer, the ink in the vicinity of the nozzles of the droplet discharge heads 21 to 25 is dried by the heat of the medium P, so that normal ink discharge cannot be performed in the droplet discharge heads 21 to 25. There was a problem of becoming an image. In the inkjet printer 1 of the present embodiment, it has been confirmed that the frequency of ink non-ejection increases when the temperature near the heads 21 to 25 is 45 ° C. or higher. That is, 45 ° C. or lower is a temperature at which ejection is guaranteed.

  Further, the droplet discharge heads 21 to 25 of the inkjet printer 1 are arranged in order from the upstream side to the downstream side in the transport direction α of the medium P. Then, the medium P is gradually stored by the primary drying mechanism 20A and the secondary drying mechanism 20B, and the medium P under the white ink droplet discharge head 25 has the highest temperature. In particular, when the medium P is a medium having a high heat storage property, the tendency is remarkable. However, as described with reference to FIG. 5, the temperature of the medium P needs to be constant in order to obtain stable image quality.

  Therefore, in the ink jet printer 1 of the second embodiment, the control unit controls the step of increasing the temperature of the medium P under the droplet discharge heads 21 to 25 from the upstream side to the downstream side in the transport direction α of the medium P. 70 is a medium P by hot air spraying of the hot air spraying section 50 of each secondary drying mechanism 20B provided corresponding to each of the droplet discharge heads 21 to 25 from the upstream side to the downstream side in the transport direction α of the medium P. The heating temperature of the secondary drying mechanism 20B from the upstream side to the downstream side in the conveyance direction α of the medium P is decreased stepwise with an upper limit of 5 ° C.

  As described above, according to the present embodiment, the control unit 70 sets the heating temperature of the medium P by the hot air blowing of the hot air blowing unit 50 of the secondary drying mechanism 20B from the upstream side to the downstream side in the conveyance direction α of the medium P. The temperature was decreased stepwise up to 5 ° C. Thereby, the temperature of the medium P can be made constant and stable image quality can be obtained.

(Third embodiment)
Next, a third embodiment will be described. In addition, the same part as 1st Embodiment or 2nd Embodiment mentioned above is shown with the same code | symbol, and description is also abbreviate | omitted.

  As described in the first embodiment and the second embodiment, according to the image forming process from ink application to drying on the medium P, the image quality varies depending on the temperature of the medium P. Therefore, it is necessary to obtain a stable image that the temperature of the medium P is constant. Further, the medium P is gradually stored by the primary drying mechanism 20A and the secondary drying mechanism 20B, and the medium P under the white ink droplet discharge head 25 becomes the highest temperature.

  Here, FIG. 6 is a front view showing a schematic configuration of the inkjet printer 1 according to the third embodiment, and FIG. 7 is a block diagram showing a hardware configuration of the inkjet printer 1. As shown in FIGS. 6 and 7, in the ink jet printer 1 of the third embodiment, the non-contact temperature sensors 29c, 29m, 29y, 29w is provided. The non-contact temperature sensors 29c, 29m, 29y, and 29w detect the ambient temperature in the vicinity of the droplet discharge heads 21 to 25. The non-contact temperature sensors 29c, 29m, 29y, and 29w are connected to the input side of the control unit 70.

  When the detected temperature in the non-contact temperature sensors 29c, 29m, 29y, and 29w is 45 ° C. or higher (over the temperature at which ejection is guaranteed), the control unit 70 is positioned upstream according to the increment. The heating temperature of the medium P by the hot air blowing of the hot air blowing unit 50 of the secondary drying mechanism 20B corresponding to any one of the droplet discharging heads (for example, the droplet discharging head located in the preceding stage or the preceding stage) is set. While lowering, the air speed of the hot air blowing unit 50 is increased. The increase in the wind speed of the hot air spraying part 50 in this way is eliminated by increasing the wind speed of the hot air spraying part 50 by reducing the drying efficiency of the ink caused by lowering the heating temperature of the medium P. It is to do. The relationship between the hot air blowing speed of the hot air blowing unit 50 and the suction pressure by the pair of heating units 28 is as shown in FIG.

  Thus, according to this embodiment, the heat storage of the media P can be suppressed, the temperature of the media P can be kept constant, and stable image quality can be obtained.

DESCRIPTION OF SYMBOLS 1 Liquid discharge apparatus 10 Feed part 11 Roll part 12 Pre-coat application part 13 Pre-coat drying apparatus 16 Conveyance guide 20 Drying part 20A Primary drying mechanism 20B Secondary drying mechanism 21-25 Droplet discharge head 26 Heater 28 Heating part (Suction) Part)
29c, 29m, 29y, 29w Non-contact temperature sensor 30 Conveying unit 40 Winding unit 50 Hot air blowing unit 51 Housing 52 Blowing hole 54 Heater 70 Control unit P Recording medium (media)
Pa Upstream part Pb Downstream part Pc Lower end Pd Ink application surface

JP 2001-334647 A

Claims (9)

In a drying device that dries ink on a recording medium applied by discharging from a droplet discharge head,
A primary drying mechanism that heats the recording medium conveyed while facing the droplet discharge head;
The primary drying mechanism is arranged downstream of the recording medium in the conveyance direction, suspends the recording medium in a U-shape, and warms the ink toward the ink application surface of the recording medium suspended in the U-shape. A secondary drying mechanism that blows wind;
A controller for controlling the primary drying mechanism and the secondary drying mechanism;
A drying apparatus comprising: The secondary drying mechanism has a suction portion that sucks an upstream portion and a downstream portion on the ink non-application surface of the recording medium suspended in a U-shape, and the suction portion is a U-shape. Arranged opposite to both sides sandwiching the non-ink-coated surface of the recording medium in the shape,
The drying apparatus according to claim 1. The control unit sets the temperature of the recording medium by heating of the primary drying mechanism in a range of 40 ° C. to 80 ° C. when the recording medium conveyance speed is 30 to 50 m / min.
The drying apparatus according to claim 1 or 2, wherein The control unit sets the wind speed of the hot air blown from the secondary drying mechanism to the recording medium when the recording medium conveyance speed is 30 to 50 m / min, at a wind speed of 10 m / sec or more on the ink application surface of the recording medium. And the temperature of the recording medium is set in the range of 60 ° C to 100 ° C.
The drying apparatus according to any one of claims 1 to 3, wherein The control unit is configured such that the suction pressure by the suction unit is greater than the dynamic pressure of the warm air from the secondary drying mechanism.
The drying apparatus according to claim 2. The control unit has a difference between the dynamic pressure of the warm air by the secondary drying mechanism and the suction pressure by the suction unit is 5 kPa or less,
The drying apparatus according to claim 5. The control unit heats the recording medium by blowing hot air from a plurality of the secondary drying mechanisms respectively provided corresponding to the plurality of droplet discharge heads from the upstream side to the downstream side in the conveyance direction of the recording medium. The temperature is decreased stepwise up to 5 ° C. in the plurality of secondary drying mechanisms from the upstream side to the downstream side in the conveyance direction of the recording medium,
The drying apparatus according to any one of claims 1 to 6, wherein A non-contact temperature sensor for detecting an ambient temperature in the vicinity of the droplet discharge head at a position near the droplet discharge head and facing the recording medium;
When the temperature detected by the non-contact temperature sensor is equal to or higher than the temperature at which ejection by the droplet ejection head is guaranteed, the control unit is configured so that any one of the droplets positioned on the upstream side according to the increase amount. Reducing the heating temperature of the recording medium by blowing hot air of the secondary drying mechanism corresponding to the discharge head, and increasing the air speed of hot air blowing of the secondary drying mechanism;
The drying apparatus according to any one of claims 1 to 6, wherein A transport unit for transporting the recording medium;
A droplet discharge head for discharging and applying ink onto the recording medium transported by the transport unit;
The drying device according to any one of claims 1 to 8, wherein the ink on the recording medium applied by discharging from the droplet discharge head is dried;
A controller that controls the transport unit, the droplet discharge head, and the drying device;
A liquid ejection apparatus comprising:

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