JP2009241277A - Liquid ejection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid ejection device coping with high speed printing by more effectively preventing bleeding, etc. with a simpler mechanism. <P>SOLUTION: The liquid ejection device includes: a liquid ejection head 11 in which a nozzle opening for ejecting liquid is provided in parallel; and a conveying means which conveys at least one of the liquid ejection head and a medium 1 to be ejected, to relatively move the liquid ejection head 11 and the medium 1 to be ejected and face them to each other in an area to be ejected. A heating means 70 for heating the medium to be ejected from its front surface is provided on the upstream side from the area to be ejected in the relative movement direction of the medium to be ejected, to perform preheating so that the temperature of the medium 1 to be ejected of the area to be ejected becomes a predetermined range temperature. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a liquid ejecting apparatus including a liquid ejecting head, and relates to a liquid ejecting apparatus that enables high-speed printing or the like by promoting drying of droplets after landing on a recording medium.

  Conventionally, for example, when performing high-speed printing with a line printer or the like, if the solvent such as water droplets is not evaporated and dried as soon as possible after droplet landing, the adjacent droplets mix with each other and print quality deteriorates (bleeding) , Agglomeration).

  Heretofore, the following printers have been proposed as printers that actively heat the recording medium and actively dry the droplets. For example, there is one that heats a recording medium in a printing area from the lower surface with a contact heating device (see Patent Document 1). Also, there is an apparatus that improves the fixing of hot melt ink by providing a preheat platen and a main platen having a main heater (see Patent Document 2). In addition, when printing with solvent ink, a preheater that preheats the media and a print heater that heats the media at the center of the platen are provided, and the ratio of preheat and print heat is determined by the media type, its thickness, and ambient temperature. A technique of adjusting according to the above has been proposed (see Patent Document 3).

  In such a technique, the recording medium is heated from the back side and the heating temperature is adjusted according to the thickness of the recording medium, etc., but it is very difficult to control to a desired temperature during recording. There is a problem. Further, assuming that water-based ink is used instead of solvent-based ink, there is a problem that the heating control method needs to be changed.

JP-A-11-129462 (Claims) JP-A-11-020141 (Claims) International Publication No. 04/094150 (claims, etc.)

  However, when water-based droplets are used, considering the evaporation of water after landing and the drying at the nozzle opening of the droplet ejecting head, the preferable temperature range in the printing region that can favorably accelerate the evaporation of water after landing is It is almost constant and does not require complicated control as in the prior art, and it is necessary to consider means different from the heating mechanism of the solvent system.

  In view of such circumstances, an object of the present invention is to provide a liquid ejecting apparatus that can effectively prevent bleeding and cope with high-speed printing with a mechanism as simple as possible.

An aspect of the present invention that achieves the above object includes a liquid ejecting head in which nozzle openings for ejecting liquid are arranged in parallel, and at least one of the liquid ejecting head and the ejection target medium, A liquid ejecting apparatus that includes a transport unit that relatively moves the ejected medium to oppose each other in the ejected area, and is upstream of the ejected area in the relative movement direction of the ejected medium. In the liquid ejecting apparatus, heating means for heating the ejected medium from the surface side is provided, and preheating is performed so that the temperature of the ejected medium in the ejected region becomes a temperature in a predetermined range.
In such an aspect, since the temperature of the ejected medium in the ejected area becomes a predetermined temperature by providing a heating unit that preheats the ejected medium from the surface side, evaporation of the droplet after landing is appropriately controlled, High image quality and high-speed printing can be supported.

  Here, it is preferable to include a temperature sensor that measures the surface temperature of the ejection medium in the ejection region, and a control unit that feedback-controls the heating condition of the heating unit based on the temperature detected by the temperature sensor. According to this, the surface temperature of the ejection medium in the ejection area is more appropriately controlled so as to be within a predetermined range, and it is possible to cope with high image quality and high-speed printing.

  Moreover, it is preferable that a heating condition is set so that the temperature of the ejection medium in the ejection area may be 40 to 45 ° C. According to this, since the temperature of the ejected medium is adjusted to 40 to 45 ° C., it is possible to prevent the nozzle opening of the liquid ejecting head from being dried while appropriately maintaining the evaporation of the droplets, and to achieve high image quality and high speed. Can support printing.

  Moreover, it is preferable that the said ejection target medium is paper and the said heating means changes a heating condition according to the basic weight used. According to this, by appropriately controlling the heating condition of the heating means from the front side according to the weighing of the paper, the ejected medium can be preheated more appropriately, and it corresponds to high image quality and high-speed printing. be able to.

  A support portion that supports the ejected medium from a surface opposite to the surface to be ejected, and is provided on a member in contact with the support portion or the support portion to supplementarily heat the support portion; It is preferable to provide auxiliary heating means. According to this, by providing an auxiliary heating means in the support portion, it is possible to compensate for a temperature drop due to heat radiation from the ejected medium in the support portion, and thereby it is possible to more appropriately control the temperature of the ejected medium. High image quality and high-speed printing can be supported.

  Further, it is preferable that the auxiliary heating unit is not provided in a region facing the nozzle opening of the liquid jet head. According to this, drying of the nozzle opening of the liquid jet head can be prevented as much as possible, and high-quality printing and high-speed printing can be supported.

Hereinafter, an example of the liquid ejecting apparatus of the invention will be described in detail.
FIG. 1 is a schematic perspective view of a liquid ejecting apparatus, and FIG. As shown in these drawings, the liquid ejecting apparatus is provided on the side of the liquid ejecting head unit 10, the platen unit 20 provided below and opposite to the liquid ejecting head unit 10, and the platen unit 20. A cap unit 30, a medium supply unit 40 for supplying the recording medium 1 to be printed on the upstream side of the platen unit 20, a medium receiving unit 50 for storing the recording medium 1 printed on the downstream side of the platen unit 20, and a medium Conveying means 60 for conveying the recording medium 1 from the supply unit 40 onto the platen unit 20 and conveying the printed recording medium 1 to the medium receiving unit 50 is provided.

  The liquid ejecting head unit 10 is capable of line printing by arranging a plurality of liquid ejecting heads 11 side by side in a direction crossing the transport direction of the recording medium 1 as an ejected medium, and is placed on a moving bar 12. It is movable in a direction crossing the transport direction, and is movable from the platen unit 20 to the cap unit 30 when not in operation.

  Here, the structure of the liquid ejecting head 11 and the type of liquid to be ejected are not particularly limited. In the present embodiment, the laminated piezo-type liquid ejecting head 11 is used, and water-based pigment ink is ejected onto the recording medium 1 made of paper. It was supposed to be.

  The platen unit 20 includes a platen belt 21 that also serves as a conveyance belt for the recording medium 1 in the platen unit 20. As illustrated in FIG. 2, the platen belt 21 includes an upstream drive roll 22 and a downstream driven roll. 23 and a tension roll 24 arranged below between them and are provided so as to be rotatable. Here, the platen belt 21 corresponds to a support portion of the present invention. Note that conveyance belts 61 and 62 having the same configuration as the platen belt 21 are provided on the upstream side and the downstream side of the platen unit 20, and these constitute a conveyance unit 60 that conveys the recording medium 1. .

  The cap unit 30 includes a plurality of caps corresponding to the respective liquid ejecting heads 11, and capping the nozzle opening surface of the liquid ejecting head 11 with the caps during non-operation, thereby allowing the liquid ejecting head 11 to be capped. This prevents the nozzle opening from drying.

  A heating unit 70 that pre-heats the recording medium 1 conveyed on the conveyance belt 61 is provided at a position facing the conveyance belt 61 disposed on the upstream side of the platen unit 20. The heating means 70 includes a heat roll 71 that contacts the surface of the recording medium 1 being conveyed and heats the surface of the recording medium 1, and in order to ensure sufficient contact between the heat roll 71 and the recording medium 1, Opposing rolls 72 are provided so as to face the heat roll 71 and sandwich the recording medium 1 and the conveyance belt 61.

  Here, the heating unit 70 is configured such that the heating condition is set so that the temperature of the recording medium 1 heated by the heating unit 70 and conveyed to the platen unit 20 becomes a predetermined temperature, and this heating condition is controlled. Controlled by means 80. The control unit 80 sets the heating condition based on the setting information such as the environmental temperature and the recording medium 1 to be used. In the present embodiment, the control unit 80 is provided in the liquid ejecting head unit 10 and detects the surface temperature of the recording medium 1. The heating conditions are finely adjusted by acquiring information from the temperature sensor 81 and performing feedback control based on the temperature information.

  Further, the platen unit 20 is provided with auxiliary heating means 90 for auxiliary heating of the recording medium 1 conveyed to the platen unit 20. The auxiliary heating means 90 includes heaters 91 to 93 provided so as to come into contact with the back surface of the platen belt 21 that is a support portion that is supported from the side opposite to the recording medium 1 and the surface to be ejected. The heaters 91 to 93 are divided and provided in the transport direction so as not to face directly below the nozzle openings of the liquid jet head 11 of the liquid jet head unit 10. The liquid jet head 11 is disposed so as to face the liquid jet head 11.

  The heaters 91 to 93 of the auxiliary heating means 90 are provided to supplement the heat escaped from the recording medium 1 preheated by the heating means 70, and the recording conveyed to the platen unit 20 by preheating. The medium 1 is maintained at a constant temperature that is equal to or slightly higher than a predetermined temperature that is the target temperature of the medium 1.

  Further, on the downstream side of the platen unit 20, a post heating unit 100 for post heating the recording medium 1 on which the liquid is jetted is provided. The post heating unit 100 is a heating unit that heats the recording medium 1 in a non-contact manner provided opposite to the upper side of the conveyance belt 62, and is, for example, an infrared heater.

  Hereinafter, the heating method of the recording medium 1 of the liquid ejecting apparatus of the present embodiment will be described in more detail.

  As described above, it has been found that the surface temperature of the recording medium 1 at the time of droplet landing is important in order to effectively prevent bleeding and the like particularly when printing is performed by jetting an aqueous liquid. Further, it was found that when the paper type is changed as the recording medium 1, it is difficult to control the heating conditions by heating from the back side, and the surface temperature of the recording medium 1 often deviates from the desired range.

  Therefore, in the present invention, as described above, the heating means 70 for preheating the recording medium 1 from the surface side is provided, the surface temperature of the recording medium 1 is directly controlled, and the surface temperature of the recording medium 1 is more easily desired. It was made to be in the range.

  The heating means 70 preheats the surface temperature of the recording medium 1 conveyed to the platen unit 20 so as to be a predetermined temperature. The heating means 70 takes into account the degree of cooling by conveyance after preheating. Set the temperature.

  In the present embodiment, the preheating conditions are adjusted so that the surface temperature of the recording medium 1 conveyed to the platen unit 20 is in the range of 40 to 45 ° C.

  When such a surface temperature is reached, when the droplets made of water-based pigment ink land, the droplets are appropriately evaporated and dried, and deterioration of print quality due to bleeding (color mixing) or the like can be prevented. That is, when the surface temperature of the recording medium 1 is less than 40 ° C., the desired evaporation and drying of the droplets cannot be obtained, which may cause a decrease in print quality due to bleeding (color mixing) or the like. On the other hand, when the surface temperature of the recording medium 1 is higher than 45 ° C., the liquid in the nozzle openings of the liquid jet head 11 is dried and stable ejection cannot be obtained, which is not preferable. On the other hand, if the temperature is too high, it may adversely affect the durability life of the bonded portion of the liquid ejecting head 11, or the spread of the dot diameter after droplet landing may be suppressed more than necessary. A large amount of droplet is required, which is not preferable.

  Further, in the present embodiment, the heat roll 71 is used as the heating unit 70 and the recording medium 1 is heated in direct contact with the recording surface. However, according to this, the surface of the recording medium 1 is surely and efficiently used. Therefore, there is an advantage that it can be heated to a desired temperature. Of course, a non-contact heating method may be used, and in any case, it is preferable to set the surface temperature of the recording medium 1 to a temperature within a desired range.

  Further, the heating means 70 preheats the recording medium 1 conveyed to the platen unit 20 as described above so that the surface temperature becomes 40 to 45 ° C., and dissipates heat in the conveyance process to the platen unit 20. The heating conditions are set in consideration of the environmental temperature, the type of the recording medium 1 to be used, and when the recording medium 1 is paper, the heating conditions can be set according to the basis weight and the like. It has become. That is, when the recording medium 1 has a large basis weight and is thick, it is difficult to be heated, so it is necessary to set the heating temperature high. When the recording medium 1 has a small basis weight and is thin, it is easily heated. Therefore, it is necessary to set the heating temperature lower. Further, if the environment temperature is low and it is easy to dissipate heat, the temperature is set high, and if the environment temperature is high and it is difficult to dissipate heat, a low heating temperature may be used.

  Here, in the present embodiment, an example of the set temperature of the heat roll 71 is shown below in relation to the basis weight of the recording medium 1. It is assumed that the conveyance speed of the recording medium 1 is 8 to 12 (IPS: inch / sec).

  In general, the surface temperature of the recording medium 1 of the platen unit 20 may be set to 40 to 45 ° C. by changing the setting as described above. However, in this embodiment, the heating unit 70 is controlled. Control means 80 is provided. As described above, the control unit 80 acquires temperature information from the temperature sensor 81 and controls the heating unit 70 based on the temperature information. The temperature sensor 81 is not particularly limited as long as it can detect the surface temperature of the recording medium 1 without contact. In addition, the control unit 80 acquires position information of the recording medium 1 and acquires temperature information when the recording medium 1 exists below the temperature sensor 81. Then, the control means 80 determines whether or not the surface temperature of the recording medium 1 is within a predetermined temperature range. If the temperature is lower than the predetermined range, the control unit 80 controls the heating condition in the high temperature direction, and if higher than the predetermined range. The heating conditions are controlled in the low temperature direction.

  Further, the heating conditions of the heaters 91 to 93 of the auxiliary heating means 90 are basically constant, and in this embodiment, the target temperature of the recording medium 1 is set, and the recording medium on the platen unit 20 is set. 1 is supplementarily heated. However, the control unit 80 may control only on / off according to the heating condition of the heating unit 70 and the temperature information of the temperature sensor 81.

  Further, as described above, the heaters 91 to 93 are provided so as not to be disposed directly below the liquid jet head 11. This is because when the portion directly under the liquid jet head 11 is heated, the influence on the head nozzle surface is increased.

  The post heating means 100 is for drying to some extent in order to stack the recording medium 1 after printing on the medium receiving portion 50, and has little influence on prevention of color mixing, which is the object of the present invention. Therefore, it goes without saying that the post heating means 100 is not particularly required.

(Other embodiments)
The liquid ejecting apparatus according to one embodiment has been described above, but the present invention is not limited to the above-described embodiment. For example, although the heating unit 70 is the contact type heat roll 71, it may be a non-contact type heating unit. 3 and 4 show an example in which an infrared heater 71A is provided as a non-contact type heating means. In addition, since it is the same as that of embodiment mentioned above except providing the infrared heater 71A, the same code | symbol is attached | subjected to another structural member and the overlapping description is abbreviate | omitted.

  Further, although the auxiliary heating unit 90 is exemplified by the back surface heating method, the auxiliary heating unit 90 is a heating unit that heats the liquid jet head 11 in a non-contact manner, for example, an infrared heater, It is good also as a wind heating, a radiant heat heater, etc.

  Further, as described above, the present invention can be suitably applied to a liquid ejecting apparatus that ejects an aqueous liquid, but can also be applied to an apparatus that ejects a solvent-based liquid. Further, although water-based pigment ink is used as the water-based liquid, it goes without saying that water-based dye ink can also be used in the same manner.

  Furthermore, in the above-described embodiment, the recording medium is transported and the recording head and the heating unit are fixed. However, the recording medium may be fixed and the recording head and the heating unit may be moved. In this case, the heating unit moves in advance of the recording head and preheats the upstream side in the relative movement direction of the recording medium. In this case, when the auxiliary heating means is provided, the auxiliary heating means may be provided in the entire movement range of the ejection area that moves with the movement of the recording head, or may be provided so as to move with the recording head. . Further, when the auxiliary heating means is provided so as to move together with the recording head, it is preferable that the auxiliary heating means is provided so as not to face directly below the nozzle opening of the recording head.

  In the above-described embodiment, the liquid ejecting apparatus capable of line printing is exemplified, but a serial printing type in which the head unit is scanned may be used.

  In the above-described embodiment, the longitudinal vibration type ink jet recording head is exemplified, but the present invention is not limited to this. For example, the flexural vibration type ink jet recording head or a bubble generated by the heat generated by the heating element can be An ink jet recording head that discharges droplets may be used.

1 is a schematic perspective view of a liquid ejecting apparatus according to an embodiment. It is a principal part schematic sectional drawing of the liquid ejecting apparatus which concerns on embodiment. It is a schematic perspective view of the liquid ejecting apparatus according to another embodiment. It is a schematic sectional drawing of the head unit which concerns on other embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Recording medium, 10 Liquid ejecting head unit, 11 Liquid ejecting head, 20 Platen part, 60 Conveying means, 70 Heating means, 71 Heat roll, 80 Control means, 81 Temperature sensor

Claims (6)

A liquid ejecting head in which nozzle openings for ejecting liquid are arranged side by side, and at least one of the liquid ejecting head and the ejected medium are transported, and the liquid ejecting head and the ejected medium are moved relative to each other. A liquid ejecting apparatus including a conveying unit that makes both face each other in an ejection region,
A heating means for heating the ejected medium from the surface side is provided upstream of the ejected area in the relative movement direction of the ejected medium so that the temperature of the ejected medium in the ejected area becomes a temperature within a predetermined range. A liquid ejecting apparatus characterized by preheating. The temperature sensor which measures the surface temperature of the ejection medium in the ejection area, and the control means which feedback-controls the heating condition of the heating means based on the temperature detected by the temperature sensor. The liquid ejecting apparatus according to 1. 3. The liquid ejecting apparatus according to claim 1, wherein the heating unit is configured such that a heating condition is set so that a temperature of a medium to be ejected in the ejected region is 40 to 45 ° C. 4. The liquid according to any one of claims 1 to 3, wherein the ejection medium is paper, and the heating unit is configured to change a heating condition according to a basis weight to be used. Injection device. Auxiliary heating that includes a support portion that supports the ejection target medium from a surface opposite to the ejection target surface, and is provided on a member that is in contact with the support portion or the support portion to supplementarily heat the support portion. The liquid ejecting apparatus according to claim 1, further comprising a unit. The liquid ejecting apparatus according to claim 5, wherein the auxiliary heating unit is not provided in a region facing the nozzle opening of the liquid ejecting head.

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