JP2012201044A - Printer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a printer having a configuration in which a deformation of a recording medium caused by presence of a non-printed portion can be prevented even when drying by a heating process is applied to the recording medium.SOLUTION: A plurality of heaters are juxtaposed in a conveyance direction of a recording medium. When a recording medium which is provided on a conveyance means after printing is subjected to a drying process, controlling of heating by the plurality of heaters is performed on the basis of image data whereby the printing is performed on the recording medium, and consequently different heating quantities are applied to a printed portion and a non-printed portion, respectively. Therefore, it is possible to prevent evaporation of water from the non-printed portion so that deformation of the recording medium can be prevented.

Description

  The present invention relates to a printing apparatus including a drying unit that heats a recording medium that has been printed based on image data in a printing machine.

  In an inkjet printing apparatus that prints on a continuous long recording medium, printing is performed by ejecting ink from a plurality of inkjet nozzles on a recording medium that is supported and conveyed by a plurality of rollers. In a printing apparatus provided with a plurality of rollers in the conveyance path of the recording medium, when conveying the recording medium after printing, there is a problem in that the ink is transferred to the roller in contact with the printing surface and the printed matter is stained. It becomes. For this reason, in order to prevent the occurrence of such a printing defect, a printing machine having a drying means for drying ink immediately after printing has been proposed.

JP 2001-5317 A

However, in the apparatus described in Patent Document 1, since the recording medium is brought into contact with the heat roller and dried, the ink is discharged even in the portion where the image is printed, that is, the portion where the ink is discharged (printed portion). The same amount of heat is applied to a portion that has not been or has not been performed (non-printed portion).
Therefore, when the amount of heat for sufficient drying is applied to the recording medium when the amount of ink ejected is large (the printing amount is large), it is not the ink solvent but the recording medium that evaporates from the non-printing area. Due to the moisture, the deformation of the recording medium such as curl or seaweed undulation has been a factor in causing poor conveyance, defective printing in the subsequent process, or defective cutting and bookbinding processes.

  Such a problem may occur not only in an ink jet printing apparatus but also in an offset printing machine. The same problem can occur even if the recording medium is not a long sheet but a sheet.

Accordingly, in order to solve the above problems, the present invention provides a drying machine for a printing press having a configuration that prevents deformation of the recording medium caused by the presence of a non-printing portion even if the recording medium is dried by heat treatment. An object is to provide an apparatus.
Alternatively, an object of the present invention is to provide a printing apparatus including a drying unit having a configuration for preventing deformation of a recording medium caused by the presence of a non-printing portion.

  In order to solve such a problem, the invention described in claim 1 includes a printing unit that prints an image based on image data on a recording medium, and transports the recording medium from a recording medium supply unit to the printing unit. And a conveying unit that conveys the recording medium printed by the printing unit to a recording medium storage unit, wherein the recording medium is conveyed to the conveying unit after printing by the printing unit. Heating means in which a plurality of heaters orthogonal to the direction are arranged, and heater control for performing heating control of the plurality of heaters of the heating means corresponding to an image printed on the recording medium based on the image data And a recording medium drying means.

  The invention according to claim 2 is the printing apparatus according to claim 1, wherein the heater control means of the recording medium drying means corresponds to the density of the image based on the image data. It is characterized by performing heating control of a plurality of heaters of the means.

  Furthermore, the invention according to claim 3 is the printing apparatus according to claim 1, wherein the heater control means of the recording medium drying means corresponds to the number of pixels of the image based on the image data, and It is characterized by controlling the heating of a plurality of heaters of the heating means.

  In addition, the invention according to claim 4 is the printing apparatus according to claim 1, wherein the heater control means of the recording medium drying means applies a photographed image obtained by photographing the image printed on the recording medium. Correspondingly, a plurality of heating controls of the heating means are performed.

  The invention according to claim 5 is the printing apparatus according to claim 1, wherein the printing unit is inkjet printing, and the heater control unit of the recording medium drying unit is based on the image data. Corresponding to the ink ejection performed by the printing unit, heating control of a plurality of heaters of the heating unit is performed.

  Further, the invention according to claim 6 is the printing apparatus according to claim 1, wherein the printing means is offset printing, and the heater control means of the recording medium drying means is based on the image data. The heating control of the plurality of heaters of the heating unit is performed corresponding to the ink key opening degree performed by the printing unit.

  In addition, a seventh aspect of the invention is the printing apparatus according to the first to sixth aspects, wherein the plurality of heaters of the heating means of the recording medium drying means are each parallel to the conveyance direction of the recording medium. It has the heating area | region which carries out.

  The invention according to claim 8 is the printing apparatus according to claims 1 to 7, wherein the plurality of heaters of the heating means of the recording medium drying means are infrared heaters. Yes.

  The invention described in claim 9 is the printing apparatus according to any one of claims 1 to 7, wherein the plurality of heaters of the heating means of the recording medium drying means are microwave heaters. It is said.

  The printing apparatus according to any one of claims 1 to 9, wherein a plurality of heaters are arranged in a line in the conveyance direction of the recording medium, and printing is performed on the recording medium when the printing unit provided in the conveyance unit performs a drying process. By controlling the heating of a plurality of heaters based on the performed image data, it is possible to prevent moisture evaporation from the non-printing portion by applying different amounts of heat to the printing portion and the non-printing portion. Can be prevented from being deformed.

  In particular, the printing apparatus according to claim 2 performs heating control of a plurality of heaters corresponding to the density of the image based on the image data, so that a portion having a high image density, that is, a portion where ink ejection has been performed. By strongly heating and weakly heating the low image density portion, that is, the portion where there is no ink discharge or low ink discharge, moisture evaporation from the non-printing portion can be prevented, so that deformation of the recording medium is prevented. be able to.

  In particular, the printing apparatus according to claim 3 strongly controls a portion where pixels are present, that is, a portion where ink is ejected, by performing heating control of a plurality of heaters corresponding to the number of pixels of an image based on image data. By heating and weakly heating a portion without pixels, that is, a portion where ink is not ejected or a portion where ink is less ejected, moisture evaporation from a non-printing portion can be prevented, so that deformation of the recording medium can be prevented. it can.

  In particular, the printing apparatus according to claim 4 performs heating control of a plurality of heaters corresponding to a photographed image obtained by photographing an image printed on a recording medium, thereby performing printing, that is, ink ejection. Since the heated portion is heated strongly and the portion that has not been printed, that is, the portion that does not discharge ink or the portion that does not discharge ink is heated weakly, moisture evaporation from the non-printed portion can be prevented. Can be prevented from being deformed.

  In particular, the printing device according to claim 5 strongly heats a portion where ink is ejected by performing heating control of a plurality of heaters in response to ink ejection based on image data in the ink jet printing device, By weakly heating a portion where there is no ink discharge or little ink discharge, moisture evaporation from the non-printing portion can be prevented, so that deformation of the recording medium can be prevented.

  In particular, the printing apparatus according to claim 6 strongly heats a portion where the ink key opening is large by performing heating control of the plurality of heaters corresponding to the ink key opening based on the image data in the offset printing apparatus. Further, by weakly heating the portion where the ink key opening is small, moisture evaporation from the non-printing portion can be prevented, so that deformation of the recording medium can be prevented.

  In particular, the printing apparatus according to claim 7 is transported because the plurality of heaters arranged in a row orthogonal to the transport direction have heating regions so as to be parallel to the transport direction of the recording medium, respectively. Sufficient heating can be performed on the recording medium.

  Particularly, in the printing apparatus according to the eighth aspect, since the plurality of heaters are infrared heaters, the heating control for each heater in the printing portion and the non-printing portion can be executed.

  Particularly, in the printing apparatus according to the ninth aspect, since the plurality of heaters are microwave oscillators, the heating control for each heater in the printing portion and the non-printing portion can be executed.

1 is a diagram for explaining an inkjet printing apparatus 100. FIG. It is a figure for demonstrating the discharge part 3 and the drying part 4. FIG. 4 is a flowchart for explaining drying control corresponding to the density of an image based on image data in the inkjet printing apparatus. It is a figure for demonstrating the state which divided | segmented the image area | region corresponding to the heater. It is a figure for demonstrating the state which is performing the heating control of several heaters corresponding to the density | concentration of an image area | region. 5 is a flowchart for explaining drying control corresponding to the number of pixels of an image based on image data in the inkjet printing apparatus 100. It is a figure for demonstrating the state which divided | segmented the image area | region corresponding to the heater. It is a figure for demonstrating the state which is performing the heating control of several heaters corresponding to the pixel number of an image area | region. 4 is a flowchart for explaining drying control corresponding to a printed image printed based on image data in the inkjet printing apparatus 100. 4 is a flowchart for explaining drying control corresponding to ink ejection of an image based on image data in the inkjet printing apparatus 100. It is a figure for demonstrating the relationship between the ink discharge signals JD1-JD8 and the pixel number of the image data GD. It is a figure for demonstrating offset printing apparatus 100 '. It is a figure for demonstrating transcription | transfer part 3 'and drying part 4'. 6 is a flowchart for explaining drying control corresponding to an ink key opening degree of an image based on image data in the offset printing apparatus 100 ′. It is a figure for demonstrating the relationship between the opening degree of each ink key 31 ', and the amount of ink transfer.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
FIG. 1 is a diagram for explaining an ink jet printing apparatus 100 according to the present invention. The ink jet printing apparatus 100 is a printing apparatus that performs printing by ejecting ink onto a conveyed roll paper. The ink jet printing apparatus 100 includes a control unit 1, a transport unit 2, a discharge unit 3, a drying unit 4, and an inspection unit 5.

  The control unit 1 is for controlling the entire inkjet printing apparatus 100. The control unit 1 transports the paper 9 by the transport unit 2, ejects ink onto the paper 9 by the ejection unit 3, dries the paper 9 on which ink is ejected by the drying unit 4, and takes a print image of the paper 9 by the inspection unit 5. By controlling each of them, printing of the ink jet printing apparatus 100 on the paper 9 is realized.

The transport unit 2 is configured to transport the paper 9 in the inkjet printing apparatus 100, and includes a paper storage unit 20, a driving roller 21, and a support roller 22.
The paper storage unit 20 is for storing the paper 9 that is roll paper for printing. The paper storage unit 20a stores the paper 9 before printing, and the paper storage unit 20b stores the paper 9 after printing. Storing.
The paper 9 drawn out from the paper storage unit 20a is transported through the ejection unit 3, the drying unit 4 and the inspection unit 5 by the drive rollers 21a and 21b while being supported by the support roller 22, and is wound around the paper storage unit 20b.

The ejection unit 3 receives ink supplied from an ink tank (not shown), ejects ink according to an ink ejection signal generated by the control unit 1 based on image information, and performs printing on the paper 9.
The discharge unit 3 includes inkjet nozzle groups 30k, 30c, 30m, and 30y as a plurality of inkjet nozzle groups 30. The inkjet nozzle groups 30k, 30c, 30m, and 30y are orthogonal to the conveyance direction of the paper 9, and a discharge width that is greater than the conveyance width of the paper 9 is realized by arranging a large number of nozzles. Since the discharge unit 3 has such a configuration, the discharge unit 3 performs printing by one discharge without performing reciprocal scanning in the conveyance width direction of the paper 9.
Note that the number of inkjet nozzle groups in the ejection unit 3 is not limited to four, and the number of inkjet nozzle groups may be one for monochromatic ejection, or 5 to perform ejection with a special color added. Two or more inkjet nozzle groups may be provided.

The drying unit 4 fixes the ink by evaporating the solvent (mainly water) of the ink by applying heat to the paper 9 after printing by the discharge unit 3 with a heater.
The drying unit 4 includes a heater 40 so as to straddle the sheet 9 conveyed by the conveyance unit 2 so as to cross over the sheet 9 in a direction orthogonal to the conveyance direction. The heater 40 performs an appropriate drying process on the paper 9 based on the drying process signal DD from the control unit 1 (details will be described later).
As the heater 40, it is desirable to use a heater having high reactivity in order to perform heating control in response to changes in image data to be printed. Specifically, a heater such as an infrared heater or a microwave oscillator that can control the heating output by responding to changes in the supplied voltage is used as the heater 40.

The inspection unit 5 captures a print image in order for the control unit 1 to determine whether or not the printing performed on the paper 9 is good. The inspection unit 5 captures a printed image printed on the conveyed paper 9 by a CCD line sensor or a CCD camera, and transmits imaging information to the control unit 1. The control unit 1 determines whether or not the printing is good by comparing the image information used for performing the ink discharge and the photographing information to determine whether or not there is a discharge failure in the discharge unit 3. be able to.
Further, the inspection unit 5 captures a print image performed on the paper 9 for use in drying control in the drying unit 4 (details will be described later).

FIG. 2 is a diagram for explaining the discharge unit 3, the drying unit 4, and the inspection unit 5 of the inkjet printing apparatus 100.
As shown in the drawing, the ejection unit 3 includes an inkjet nozzle group 30 so as to be orthogonal to the sheet 9 conveyed by the conveyance unit 2. Here, in order to simplify the description, the inkjet nozzle group 30 of only one color is illustrated, and the inkjet nozzle group 30 is configured by eight inkjet heads of inkjet heads 30a to 30h.
The inkjet nozzle group 30 of the ejection unit 3 ejects ink to print an image on the paper 9 based on the ink ejection signal JD transmitted from the control unit 1. Since the width of the inkjet nozzle group 30 is wider than the width orthogonal to the transport direction of the paper 9, a desired image can be printed according to the transport of the paper 9.
The number of inkjet heads constituting the inkjet nozzle group 30 is not limited to eight.

As shown in the drawing, the inspection unit 5 is provided so as to be orthogonal to the sheet 9 conveyed by the conveyance unit 2, and takes an image printed on the sheet 9 by the ejection unit 3. The print image photographed by the inspection unit 5 is transmitted to the control unit 1 as a photographing information ID. The control unit 1 determines whether or not the image printed on the paper 9 is good by comparing the photographing information ID with the image data GD from which the ink ejection signal JD is generated.
Further, the control unit 1 controls the drying unit 4 based on the photographing information ID from the inspection unit 5. From the photographing information ID, the control unit 1 can acquire the state in which the image is printed on the paper 9. The control unit 1 performs drying control of the drying unit 4 according to the printing state of the image on the paper 9 (details will be described later).

As shown in the drawing, the drying unit 4 is provided so as to be orthogonal to the sheet 9 conveyed by the conveying unit 2, and performs a drying process on the image printed on the sheet 9 by the ejection unit 3.
The drying unit 4 includes a heater 40 including heaters 40a to 40h having a predetermined tube length. The tube lengths of the heaters 40a to 40h are determined according to the heating capacity. That is, if the heating capacity is low, it is possible to cope with the drying process of the sheet 9 by increasing the tube length of the heaters 40a to 40h and extending the drying time. On the other hand, if the heating capacity is high, the tube lengths of the heaters 40a to 40h can be shortened to shorten the drying time, so that the paper 9 can be dried.

The heating amounts of the heaters 40 a to 40 h of the drying unit 4 are changed based on the drying processing signal DD from the control unit 1. The heating amount is changed by changing the applied voltage amount based on the drying processing signal DD. That is, the drying unit 4 that has received the drying processing signal DD determines the amount of voltage to be applied to each of the heaters 40a to 40h based on the drying processing signal DD. For example, when the drying processing signal DD includes an instruction to perform strong drying by the heater 40a, the drying unit 4 applies a high voltage to the heater 40a. On the other hand, when the drying process signal DD does not require drying in the heater 40h, the drying unit 4 does not apply a voltage to the heater 40h. As a method of applying a voltage to the heaters 40a to 40h, PWM (Pulse Width Modulator) control can be employed. Further, the magnitude of the voltage may be directly controlled.
The number of heaters 40 provided in the drying unit 4 is not limited to eight. When the number of the heaters 40 is large, the drying unit 4 may perform the drying control by dividing the heater 40 by a predetermined number. As the predetermined number, for example, the number of inkjet heads constituting the inkjet nozzle group 30 can be employed.
<Drying control based on concentration>
FIG. 3 is a flowchart for explaining the drying control corresponding to the image density based on the image data in the inkjet printing apparatus 100.
The operation of the inkjet printing apparatus 100 shown in FIG. 3 is based on dividing the image G represented by the image data GD before RIP or after RIP into a plurality of areas, and based on the average density of the divided areas. Thus, the drying process in the drying unit 4 is performed.

  In step S31, image data GD to be printed by the inkjet printing apparatus 100 is acquired.

  In step S32, the control unit 1 of the inkjet printing apparatus 100 divides the acquired image data GD into a plurality of regions corresponding to the heaters 40a to 40h of the drying unit 4. The control unit 1 divides the image G represented by the image data GD into 8 regions because the heaters 40a to 40h of the drying unit 4 are eight. The dividing direction is divided in a direction parallel to the heaters 40a to 40h, that is, a direction parallel to the transport direction of the paper 9 when the image data GD is printed on the paper 9.

  In step S33, the control unit 1 calculates the average density of the images for each area obtained by dividing the image G represented by the image data GD, and gives an order based on the density for each divided area.

FIG. 4 is a diagram for explaining a state in which the image G represented by the image data GD is divided by S32 and S33. The image G represented by the image data GD is divided into eight divided regions DGD1 to DGD8 as shown in the figure. In this state, the average density of the image in each of the divided regions DGD1 to DGD8 is calculated.
Here, as shown in the figure, the divided areas DGD1 and DGD8 have a low average density because only a part of the image G occupies a part of the area. On the other hand, the average density of the divided region DGD4 in which a part of the image G occupies most of the region is high. Accordingly, as a result of the calculation of the average density, the order based on the density for each divided region is “DGD4>DGD3>DGD2>DGD5>DGD7>DGD6>DGD1> DGD8” in descending order.

  Returning to FIG. 3, in step S34, the inkjet printing apparatus 100 prints the image data GD. If the image data GD is not RIP, the control unit 1 performs RIP, converts it into binary image data, and further converts it into an ink discharge signal JD for controlling the discharge unit 3, so The image G represented by the image data GD is printed. In the case of the binarized image signal in which the image data GD is RIP, the control unit 1 converts the ink G to the ink ejection signal JD for controlling the ejection unit 3, and the image G represented by the image data GD on the paper 9 is displayed. Print.

  In step S35, the control unit 1 controls the drying unit 4 to dry the image printed on the paper 9. The control unit 1 transmits to the drying unit 4 a drying processing signal DD that changes the heating amount for each of the heaters 40a to 40h corresponding to the divided regions to which the order based on the concentration is given in step S33. The drying unit 4 changes the heating amount of the heaters 40a to 40h by changing the voltages applied to the heaters 40a to 40h based on the drying processing signal DD.

  FIG. 5 is a diagram for explaining a state in which heating control of a plurality of heaters is performed in accordance with the density of the image region, and corresponds to each of the divided regions DGD1 to DGD8 obtained by dividing the image G shown in FIG. And the change of the voltage applied to the heaters 40a-40h by the drying process signal DD is illustrated.

The drying processing signal DD is a signal for changing the voltage in eight stages, with the maximum output of each of the heaters 40a to 40h being 100. The drying unit 4 that has received the drying processing signal DD applies a voltage based on the drying processing signal DD to each of the heaters 40a to 40h. Since the voltage is applied by PWM control, the average voltage to be applied can be changed by making the frequency constant, the voltage constant, and the pulse width different.
Here, since the order based on the concentration in each divided region is “DGD4>DGD3>DGD2>DGD5>DGD7>DGD6>DGD1> DGD8”, the order of the heaters with the high applied voltage is as follows. “40d>40c>40b>40e>40g>40f>40a> 40h”.

As a result, strong drying is performed on the divided areas where the average density of the image is high, that is, areas where a large amount of ink is ejected for printing, and weak drying is performed on the divided areas where the average density of the image is low. become. As a result, different amounts of heat can be applied to the divided areas with a high average density and the divided areas with a low average density, and moisture evaporation from the divided areas with a low average density can be prevented. can do.
<Drying control based on the number of pixels>
FIG. 6 is a flowchart for explaining drying control corresponding to the number of pixels of an image based on image data in the inkjet printing apparatus 100.
The operation of the inkjet printing apparatus 100 shown in FIG. 6 is to divide the image G represented by the image data GD after RIP into a plurality of areas, and in the drying unit 4 based on the number of pixels in the divided areas. It is an aspect which performs a drying process.

In step S61, the inkjet printing apparatus 100 acquires image data GD that is binarized image data.
If the image data GD acquired in step S61 is before RIP, the control unit 1 performs RIP and converts the image data GD into binarized image data.

  In step S62, the control unit 1 of the inkjet printing apparatus 1 divides the acquired image data GD into a plurality of regions corresponding to the heaters 40a to 40h of the drying unit 4. The control unit 1 divides the image G represented by the image data GD into 8 regions because the heaters 40a to 40h of the drying unit 4 are eight. Further, the division direction is divided in a direction parallel to the heaters 40a to 40h, that is, in the conveyance direction of the paper 9 when the image data GD is printed on the paper 9.

  In step S63, the control unit 1 acquires the number of pixels in each region obtained by dividing the image data GD, and gives an order based on the number of pixels for each divided region.

FIG. 7 is a diagram for illustrating a state in which the image G represented by the image data GD is divided in step S63. The image G represented by the image data GD is divided into eight divided regions DGD1 to DGD8 as shown in the figure. The number of pixels for expressing the image G in each of the divided areas DGD1 to DGD8 is acquired as the number of pixels in each area.
Here, as shown in the drawing, since the divided regions DGD1 and DGD8 only occupy a part of the region, the number of pixels representing the image G is small. On the other hand, the number of pixels in the divided region DGD5 in which a part of the image G occupies most of the region increases. Therefore, as a result of obtaining the number of pixels, the order based on the number of pixels for each divided region is “DGD5>DGD6>DGD7>DGD4>DGD2>DGD3>DGD8> DGD1” in descending order.

  Returning to FIG. 6, in step S64, the inkjet printing apparatus 100 prints the image data GD. The control unit 1 converts the image data GD into an ink ejection signal JD for controlling the ejection unit 3, and prints an image represented by the image data GD on the paper 9.

  In step S65, the control unit 1 controls the drying unit 4 to dry the image printed on the paper 9. The control unit 1 transmits to the drying unit 4 a drying processing signal DD that changes the heating amount for each of the heaters 40a to 40h corresponding to the divided regions to which the order based on the number of pixels is given in step S63. The drying unit 4 changes the heating amount of the heaters 40a to 40h by changing the voltages applied to the heaters 40a to 40h based on the drying processing signal DD.

  FIG. 8 is a diagram for explaining a state in which heating control of a plurality of heaters is performed in accordance with the density of the image area, and corresponds to each of the divided areas DGD1 to DGD8 obtained by dividing the image G shown in FIG. And the change of the voltage applied to the heaters 40a-40h by the drying process signal DD is illustrated.

The drying processing signal DD is a signal for changing the voltage in eight stages, with the maximum output of each of the heaters 40a to 40h being 100. The drying unit 4 that has received the drying processing signal DD applies a voltage based on the drying processing signal DD to each of the heaters 40a to 40h. Since the voltage is applied by PWM control, the average voltage to be applied can be changed by making the frequency constant, the voltage constant, and the pulse width different.
Here, since the order based on the number of pixels for each divided region is “DGD5>DGD6>DGD7>DGD4>DGD2>DGD3>DGD8> DGD1” from the highest order, the order of the heaters with the highest applied voltage is high. Is "40e>40f>40g>40d>40b>40c>40h>40a".

As a result, a strong drying is performed on a divided region with a large number of pixels, that is, a region where a large amount of ink is ejected for printing, and a weak drying is performed on a divided region with a small number of pixels. As a result, different amounts of heat can be applied to the divided region with a large number of pixels and the divided region with a small number of pixels, and moisture evaporation from the divided region with a small number of pixels can be prevented, so that deformation of the paper 9 can be prevented. can do.
<Drying control based on printed images>
FIG. 9 is a flowchart for explaining drying control based on a printed image obtained by photographing an image printed on the paper 9 in the inkjet printing apparatus 100.
The operation of the inkjet printing apparatus 100 shown in FIG. 9 is an aspect in which a print image is divided into a plurality of regions, and a drying process in the drying unit 4 is executed based on the image density of the divided regions.

In step S91, the inkjet printing apparatus 100 acquires image data GD.
If the image data GD acquired in step S91 is before RIP, the control unit 1 performs RIP and converts the image data GD into binarized image data.

  In step S92, the inkjet printing apparatus 100 prints the image data GD. The control unit 1 converts the image data GD into an ink ejection signal JD for controlling the ejection unit 3, and prints an image G represented by the image data GD on the paper 9.

  In step S93, the inspection unit 5 captures an image printed on the conveyed paper 9. After ink ejection by the ejection unit 3, the paper 9 conveyed by the conveyance unit 2 passes under the inspection unit 5. At that time, the inspection unit 5 captures an image printed on the paper 9 and transmits it to the control unit 1 as a photographing information ID.

  In step S94, the control unit 1 calculates the average density of the image for each area obtained by dividing the image represented by the photographing information ID, and gives an order based on the density for each divided area.

  In step S95, the control unit 1 controls the drying unit 4 to dry the image printed on the paper 9. The control unit 1 transmits to the drying unit 4 a drying processing signal DD that changes the heating amount for each of the heaters 40a to 40h corresponding to the divided regions to which the order based on the concentration is given in step S94. The drying unit 4 changes the heating amount of the heaters 40a to 40h by changing the voltages applied to the heaters 40a to 40h based on the drying processing signal DD.

As a result, strong drying is performed on the divided area where the average density of the printed image is high, that is, the area where a large amount of ink is ejected for printing, and weak drying is performed on the divided area where the average density of the image is low. It will be. As a result, different amounts of heat can be applied to the divided areas with a high average density and the divided areas with a low average density, and moisture evaporation from the divided areas with a low average density can be prevented. can do.
<Drying control based on ink ejection signal>
FIG. 10 is a flowchart for explaining the drying control based on the ink ejection signal JD applied to the inkjet nozzle group 30 that ejects ink for printing on the paper 9 in the inkjet printing apparatus 100.
The operation of the inkjet printing apparatus 100 shown in FIG. 10 divides an image into a plurality of regions, and performs a drying process in the drying unit 4 based on an ink discharge signal for the ink jet head to discharge ink to the divided regions. This is the mode of execution.

In step S101, the inkjet printing apparatus 100 acquires image data GD.
If the image data GD acquired in step S101 is before RIP, the control unit 1 performs RIP and converts the image data GD into binarized image data.

  In step S102, the control unit 1 converts the image data GD into an ink discharge signal JD for controlling the discharge unit 3, and gives an order based on the ink discharge amount. Since the inkjet nozzle group 30 provided in the ejection unit 3 includes the inkjet heads 30a to 30h, the control unit 1 controls the ejection of ink from each inkjet head. Therefore, the image data GD that is a binarized image is used. The ink discharge signals JD1 to JD8 are converted.

  The ink discharge signals JD1 to JD8 have different ink discharge amounts depending on the number of pixels of the image data GD. FIG. 11 is a diagram for explaining the relationship between the ink ejection signals JD1 to JD8 and the number of pixels of the image data GD. The ink ejection signals JD1 to JD8 converted based on the image data GD print an image G as shown in FIG. Here, since the ink jet heads 30a and 30h have a small ink discharge amount, the corresponding ink discharge signals JD1 and JD8 are signals with a small ink discharge amount. On the other hand, since the inkjet head 40d has a large ink discharge amount, the corresponding ink discharge signal JD4 is a signal having a large ink discharge amount. As a result of the ordering based on the ink discharge amount as described above, the order of the ink discharge signals JD is “JD4> JD3> JD2> JD5> JD7> JD6> JD1> JD8” in descending order of the ink discharge amount.

  Returning to FIG. 10, in step S103, the inkjet printing apparatus 100 prints the image data GD. When the control unit 1 transmits the ink ejection signal JD to the ejection unit 3, the ejection unit 3 performs ink ejection and prints an image represented by the image data GD on the paper 9.

  In step S104, the control unit 1 controls the drying unit 4 to dry the image printed on the paper 9. The control unit 1 transmits to the drying unit 4 a drying processing signal DD that changes the heating amount of each of the heaters 40a to 40h corresponding to the ink jet head to which the order based on the ink discharge amount is given in step S102. The drying unit 4 changes the heating amount of the heaters 40a to 40h by changing the voltages applied to the heaters 40a to 40h based on the drying processing signal DD.

  Here, since the order based on the ink ejection amount is “JD4> JD3> JD2> JD5> JD7> JD6> JD1> JD8” from the highest order, the inkjet head with a large ink ejection is “30d> 30c> 30b> 30e> 30g> 30f> 30h> 30a ". Therefore, the order of the heaters with the high applied voltage is “40d> 40c> 40b> 40e> 40g> 40f> 40h> 40a” corresponding to the ink jet head that discharges many inks.

  As a result, strong drying is performed in a region where a large amount of ink is ejected for printing, and weak drying is performed in a region where the ink ejection amount is small. Since moisture evaporation can be prevented, deformation of the paper 9 can be prevented.

<Second Embodiment>
In the description so far, the drying control in the ink jet printing apparatus 100 has been described, but the present invention can also be applied to an offset printing apparatus.
FIG. 12 is a diagram for explaining the offset printing apparatus 100 ′. The offset printing apparatus 100 ′ is a printing apparatus that performs printing by transferring ink to the conveyed roll paper. The offset printing apparatus 100 ′ includes a control unit 1 ′, a transport unit 2 ′, a transfer unit 3 ′, a drying unit 4 ′, and an inspection unit 5 ′.

  The control unit 1 ′ is for controlling the entire offset printing apparatus 100 ′. The control unit 1 ′ transports the paper 9 by the transport unit 2 ′, transfers the ink to the paper 9 by the transfer unit 3 ′, dries the paper 9 on which the ink is transferred by the drying unit 4 ′, and the paper 9 by the inspection unit 5 ′. The printing of the offset printing apparatus 100 ′ on the paper 9 is realized by controlling the printing image shooting of each.

  Since the transport unit 2 ′ is the same as the transport unit 2 of the inkjet printing apparatus 100, description thereof is omitted.

  The transfer unit 3 ′ performs printing by receiving ink supplied from an ink tank (not shown) and transferring the ink applied to the printing plate onto the paper 9. Details will be described later.

The drying unit 4 ′ heats the paper 9 printed by the transfer unit 3 ′ with a heater to evaporate the ink solvent (mainly oil), thereby fixing the ink.
The drying unit 4 ′ includes a heater 40 ′ so as to straddle the sheet 9 conveyed by the conveyance unit 2 ′ perpendicularly to the conveyance direction. The heater 40 ′ performs an appropriate drying process on the paper 9 based on the drying process signal DD from the control unit 1 ′ (details will be described later).
It is desirable that the heater 40 ′ also uses a highly reactive heating device in order to perform heating control in response to changes in image data to be printed. Specifically, a heater such as an infrared heater or a microwave oscillator that can control the heating output by following and responding to changes in the supplied voltage is used as the heater 40 ′.

  The inspection unit 5 ′ captures a print image in order for the control unit 1 ′ to determine whether or not the printing performed on the paper 9 is good. The inspection unit 5 ′ uses a CCD line sensor or a CCD camera to capture a printed image printed on the conveyed paper 9, and transmits the imaging information to the control unit 1 ′.

FIG. 13 is a diagram for explaining the transfer unit 3 ′ and the drying unit 4 ′.
In addition, description about test | inspection part 5 'is abbreviate | omitted here.

  The transfer unit 3 ′ includes an ink key 31 ′, an ink cylinder 32 ′, a plate cylinder 33 ′, and a blanket cylinder 34 ′.

  The ink key 31 'supplies oil-based ink from an ink tank (not shown) to the ink cylinder 32'. The ink key 31 ′ does not uniformly supply the ink when supplying ink to the ink cylinder 32 ′. In other words, the ink key 31 ′ is composed of a plurality of ink keys 31a ′ to 31h ′ in order to change and supply the ink amount in accordance with the pattern area ratio on the printing plate P. The controller 1 'changes the opening degree of the ink keys 31a' to 31h ', thereby supplying ink corresponding to the pattern area ratio on the printing plate P.

  The ink cylinder 32 'supplies the ink supplied from the ink key 31' to the plate cylinder 33 '. As the ink is kneaded by the rotation of the ink cylinder 32 ', the highly viscous ink is smoothed and supplied to the plate cylinder 33'. Here, only two ink cylinders 32 'are shown for the sake of explanation, but in actuality, the ink cylinder 32' is constituted by a large number of cylinders.

  The plate cylinder 33 ′ is a roller for winding the printing plate P. As the plate cylinder 33 ′ rotates, when water is supplied to the printing plate P from a fountain solution device (not shown) and ink is supplied from the ink cylinder 32 ′, the ink is applied to the oleophilic portion (the pattern portion). The dampening water is placed on the hydrophilic part (the part without the pattern).

  In the blanket cylinder 34 ', only ink is transferred from the plate cylinder 33'. With the rotation of the plate cylinder 33 ', the blanket cylinder 34' also rotates. At this time, the plate cylinder 33 ′ and the blanket cylinder 34 ′ are in contact with each other, and the blanket cylinder 34 ′ is designed to transfer only ink. The image is transferred to the blanket cylinder 34 'while being maintained. Since the sheet 9 is sandwiched between an impression cylinder (not shown) and the blanket cylinder 34 ', and the ink area shape is transferred to the sheet 9 as the blanket cylinder 34' rotates, the image data GD for the sheet 9 expresses. Printing of image G is realized.

As shown in the figure, the drying unit 4 ′ is provided so as to be orthogonal to the paper 9 conveyed by the conveyance unit 2 ′, and performs a drying process on the image printed on the paper 9 by the transfer unit 3 ′. To do. Since the configuration of the drying unit 4 ′ is substantially the same as that of the drying unit 4, description thereof is omitted.
In addition, the number of heaters 40 ′ provided in the drying unit 4 ′ is not limited to eight. When the number of the heaters 40 ′ is large, the drying unit 4 ′ may perform the drying control by dividing the heater 40 ′ by a predetermined number. As the predetermined number, for example, the number of ink keys 31 ′ can be employed.

  FIG. 14 is a flowchart for explaining the drying control corresponding to the ink key opening degree of the image based on the image data in the offset printing apparatus 100 ′.

  The operation of the offset printing apparatus 100 ′ shown in FIG. 14 is a mode in which the drying process in the drying unit 4 ′ is executed based on the opening of each ink key 31 ′ for supplying ink to the plate cylinder 33 ′.

  In step S141, the printing plate P is mounted on the plate cylinder 33 ′ of the offset printing apparatus 100 ′. If the offset printing apparatus 100 ′ is a normal printing apparatus, the printing plate P created outside the offset printing apparatus 100 ′ is mounted on the plate cylinder 33 ′. If the offset printing apparatus 100 ′ is a digital printing apparatus, the image data GD is acquired, and the printing plate P created inside the offset printing apparatus 100 ′ is mounted on the plate cylinder 33 ′.

In step S142, the control unit 1 ′ of the offset printing apparatus 100 ′ sets the opening of each ink key 31 ′, and determines the order of the ink keys 31 ′ based on the opening.
The opening degree of the ink key 31 ′ is set by dividing the picture represented by the printing plate P so as to correspond to each ink key 31 ′ and by the dot area ratio for each divided region. Alternatively, the same division may be performed, and the opening degree of each ink key 31 ′ may be set according to the number of halftone dots for each divided region. When the offset printing apparatus 100 ′ is a digital printing apparatus, the image G represented by the acquired image data GD is divided so as to correspond to each ink key 31 ′, and based on the density and the number of pixels for each divided area. The opening degree of each ink key 31 ′ may be set. Or you may set the opening degree of each ink key 31 'manually.

If the opening degree of each ink key 31 ′ is set, the control unit 1 ′ determines the order of each ink key 31 ′ based on the opening degree of each ink key 31 ′.
FIG. 15 is a diagram for explaining the relationship between the opening of each ink key 31 ′ and the ink transfer amount. As shown in the drawing, the ink keys 31a ′ to 31h ′ need to have different ink transfer amounts when supplying ink for printing the image G expressed by the printing plate P. That is, the ink keys 31a ′ and 31h ′ may require a small amount of ink supply for printing, whereas the ink key 31d ′ requires a large amount of ink supply for printing. The opening degree of the key 31 ′ is “31d ′> 31a ′ or 31h ′”. Similarly, the control unit 1 ′ obtains the opening degree of the ink key 31 ′, and obtains the order of the ink keys 31 ′ based on the opening degree. Here, “31e ′> 31f ′> 31d ′> 31g ′> 31b ′> 31c ′> 31h ′> 31a ′” in descending order of the opening degree of each ink key 31 ′.

  In step S143, printing on the sheet 9 is performed by the transfer unit 3 ′. The transfer unit 3 ′ supplies ink to the ink cylinder 32 ′ in an amount corresponding to the opening degree of each ink key 31 ′ set in step S142. Ink cylinder 32 'kneads the supplied ink to lower the viscosity, and then supplies it to plate cylinder 33'. The plate cylinder 33 ′ rotates, supplies dampening water (not shown) to the printing plate P, and then supplies ink from the ink cylinder 32 ′ to the printing plate P. Ink adhering to the oleophilic layer formed on the printing plate P is transferred to the blanket cylinder 34 'as the plate cylinder 33' rotates. The ink transferred to the blanket cylinder 34 'while maintaining the area shape on the printing plate P is transferred to the paper 9 sandwiched between the impression cylinder 35', and the image G represented by the image data GD is the paper. 9 will be printed.

  In step S144, in order to dry the image printed on the paper 9, the control unit 1 ′ controls the drying unit 4 ′. The control unit 1 ′ outputs a drying processing signal DD for changing the heating amount for each of the heaters 40a ′ to 40h ′ corresponding to the ink keys 31 ′ to which the order based on the opening degree is given in step S142. Send to 4 '. The drying unit 4 ′ changes the heating amount of the heaters 40a ′ to 40h ′ by changing the voltage applied to the heaters 40a ′ to 40h ′ based on the drying processing signal DD.

  Here, the order based on the opening degree of each ink key 31 ′ is “31d ′> 31c ′> 31e ′> 31f ′> 31g ′> 31b ′> 31h ′> 31a ′” in descending order. Therefore, the order of the heaters with the high applied voltage is “40d ′> 40c ′> 40e ′> 40f ′> 40g ′> 40b ′> 40h ′> 40a ′” corresponding to the magnitude of the ink transfer amount.

  As a result, strong drying is performed in areas where a large amount of ink has been transferred for printing, and weak drying is performed in areas where the amount of ink transferred is small. Since evaporation of moisture contained in the sheet 9 can be prevented, deformation of the sheet 9 can be prevented.

<Modification>
In the description so far, the drying device in the ink jet printing apparatus and the offset printing apparatus has been described. However, for example, printing using other printing methods such as a gravure printing apparatus, a flexographic printing apparatus, a stencil printing apparatus, and a relief printing apparatus. The drying apparatus according to the present invention can also be applied to the apparatus.

  In the above description, the transport unit 2 has been described as transporting the web-shaped paper 9, but the paper 9 transported by the transport unit 2 may be a sheet.

  In the description so far, the drying unit 4 has been described as being provided with the heaters 40 for drying a part of the width of the paper 9, but for drying the entire width of the paper 9 in the subsequent stage of the heater 40. A heater may be provided. In this case, troubles in post-processing can be prevented by performing more powerful drying on the paper 9 after performing drying to prevent deformation of the paper 9.

  In the above description, the heater 40 of the drying unit 4 has been described as performing voltage control. However, the heater 40 may be heated by current control.

DESCRIPTION OF SYMBOLS 1, 1 'Control part 2, 2' Conveyance part 3 Discharge part 3 'Transfer part 4, 4' Drying part 5, 5 'Inspection part 9 Paper 30, 30k, 30c, 30m, 30y Inkjet nozzle group 31', 31a ' , 31b ', 31c', 31d ', 31e', 31f ', 31g', 31h 'Ink key 32' Ink cylinder 33 'Plate cylinder 34' Blanket cylinder 40, 40a, 40a ', 40b, 40b', 40c, 40c ', 40d, 40d' 40e, 40e ', 40f, 40f', 40g, 40g ', 40h, 40h' heater
DGD, DGD1, DGD2, DGD3, DGD4, DGD5, DGD6, DGD7, DGD8 Divided area
G image
GD image data
DD drying process information
ID shooting information
JD ink ejection information Printing plate P

Claims (9)

Printing means for printing an image based on image data on a recording medium, and the recording medium conveyed from the recording medium supply section to the printing means, and the recording medium printed by the printing means is stored in a recording medium storage section A printing device comprising a conveying means for conveying to
In the conveying means,
A heating unit in which a plurality of heaters orthogonal to the direction in which the recording medium is conveyed after printing by the printing unit;
Heater control means for performing heating control of a plurality of heaters of the heating means corresponding to an image printed on the recording medium based on the image data;
A printing apparatus, further comprising: a recording medium drying unit. The printing apparatus according to claim 1,
The heater control means of the recording medium drying means performs heating control of the plurality of heaters of the heating means in accordance with the density of the image based on the image data.
A printing apparatus characterized by the above. The printing apparatus according to claim 1,
The heater control means of the recording medium drying means performs heating control of a plurality of heaters of the heating means corresponding to the number of pixels of the image based on the image data.
A printing apparatus characterized by the above. The printing apparatus according to claim 1,
The heater control means of the recording medium drying means performs a plurality of heating controls of the heating means in response to a photographed image obtained by photographing an image printed on the recording medium;
A printing apparatus characterized by the above. The printing apparatus according to claim 1,
The printing means is inkjet printing;
The heater control unit of the recording medium drying unit performs heating control of the plurality of heaters of the heating unit in response to ink ejection performed by the printing unit based on the image data;
A printing apparatus characterized by the above. The printing apparatus according to claim 1,
The printing means is offset printing;
The heater control means of the recording medium drying means performs heating control of a plurality of heaters of the heating means corresponding to the ink key opening degree performed by the printing means based on the image data;
A printing apparatus characterized by the above. The printing apparatus according to claim 1, wherein:
The plurality of heaters of the heating means of the recording medium drying means each have a heating region parallel to the conveyance direction of the recording medium;
A printing apparatus characterized by the above. The printing apparatus according to claim 1, wherein:
The plurality of heaters of the heating means of the recording medium drying means are infrared heaters;
A printing apparatus characterized by the above. The printing apparatus according to claim 1, wherein:
The plurality of heaters of the heating means of the recording medium drying means are microwave heaters;
A printing apparatus characterized by the above.

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