JP2014083762A - Droplet drying device, printing equipment and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a droplet drying device, printing equipment, and a program, which enable a droplet to be efficiently dried with a low level of energy without impairing image quality.SOLUTION: A recording-drying combined head 32 includes a recording head 100 and a drying head 200. The recording head includes a plurality of nozzles 104 that are arrayed in a predetermined direction and eject an ink droplet 112 to a sheet P. The drying head 200 includes a plurality of VCSEL groups 206 which are provided along a predetermined direction. Each of the VCSEL groups 206 includes a plurality of VCSEL 204 which correspond to one of the plurality of nozzles 104 or to the plurality of nozzles 104, are disposed in a direction intersecting a predetermined direction and irradiate an ink droplet 112 on a sheet P with light at different points on a straight line that goes through a position or positions opposite to the plurality of nozzles 104 on the sheet P and is extended in the intersecting direction. Further, irradiation energy of individual VCSEL 204 constituting the VCSEL group 206 is controlled in accordance with an ejection volume of the ink droplet 112.

Description

  The present invention relates to a droplet drying apparatus, a printing apparatus, and a program.

  In Patent Document 1, a head body having a surface facing an object, a plurality of nozzles arranged on the surface and ejecting liquid droplets at respective positions facing the object, and disposed on the surface. A droplet discharge head including an irradiation unit configured to irradiate light toward the object, wherein i irradiation units (i is an integer of 1 or more) arranged along the nozzle arrangement direction; It has i × j irradiation parts composed of j irradiation parts (j is an integer of 2 or more) arranged in the predetermined direction of the nozzle along a predetermined direction intersecting with the arrangement direction. A droplet discharge head is disclosed.

  On the other hand, Patent Document 2 uses an ink jet head in which a plurality of nozzles are arranged in the main scanning direction, sends a recording paper or an ink jet head in the sub scanning direction, ejects ink from each nozzle, and prints an image on the recording paper. In an ink jet printer for recording, a plurality of heating means for heating the recording paper divided in the nozzle arrangement direction, and an ink discharge amount from the nozzles to a heating area to the recording paper by each heating means Accordingly, there is disclosed an ink jet printer comprising control means for controlling the heating amount of the heating means.

JP 2009-022831 A JP 2002-011860 A

  An object of the present invention is to provide a droplet drying device, a printing device, and a program capable of efficiently drying droplets with low energy without impairing the image quality.

  In order to achieve the above object, the droplet drying apparatus according to claim 1 includes a droplet discharge unit including a plurality of nozzles arranged in a predetermined direction for discharging droplets onto an object. Corresponding to each nozzle group when the plurality of nozzles are divided into a plurality of nozzle groups so as to include at least one nozzle, the nozzles are arranged in a direction intersecting with the predetermined direction and intersecting The droplets on the object that have reached the respective positions at different positions on a straight line that passes through the opposed positions of the nozzle group on the object conveyed in the direction and extends in the intersecting direction. A plurality of light source groups including a plurality of light sources for sequentially irradiating light with respect to the predetermined direction, and controlling the discharge amount of the droplets and controlling the discharge amount Before handling nozzle groups And control means for controlling the discharge amount of irradiation energy of each of the light sources constituting the light source group, those having a.

  According to a second aspect of the present invention, in the first aspect of the present invention, the control means controls the irradiation energy of each light source that constitutes the light source group, so that the temperature time of the droplets is reduced. A distribution with respect to the axis is formed.

  According to a third aspect of the present invention, in the second aspect of the present invention, the distribution of the temperature of the droplets with respect to the time axis is as follows: It includes a temperature rising region that gradually approaches the boiling temperature of the droplet from the temperature, and a boiling temperature maintaining region that is continuous with the temperature rising region and maintains the boiling temperature.

  According to a fourth aspect of the present invention, in the invention according to the third aspect, the light source of the light source that forms the temperature rising region is formed by the irradiation energy of the light source that forms the temperature rising region. It controls so that it may become larger than the irradiation energy of.

  The invention according to claim 5 is the invention according to claim 3 or claim 4, wherein the control means is the last light source to be irradiated among the light sources forming the boiling temperature maintaining region, or lastly. Control is performed so that the irradiation energy of a predetermined number of light sources including the light source to be irradiated becomes smaller than the irradiation energy of the other light sources forming the boiling temperature maintaining region.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the control means turns on and off the light source for each of the ejected droplets. The irradiation energy is controlled by switching.

  Further, in the invention according to claim 7, in the invention according to any one of claims 1 to 6, the control means controls the light intensity of each light source in the light source group to perform irradiation. It controls energy.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein each light source in the light source group emits pulsed light, and the control means includes: The irradiation energy is controlled by controlling the number of pulsed light of each light source.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, wherein the light source is a surface emitting laser.

  Further, the invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein the light source is configured to correspond to the light emission surface of each light source constituting the light source group. It further has a condensing means for condensing the emitted light.

  On the other hand, a printing apparatus according to an eleventh aspect includes a droplet drying apparatus according to any one of the first to tenth aspects and a conveying unit that conveys a printed material to be dried by the droplet drying apparatus. And.

  Furthermore, in order to achieve the above object, a program according to claim 12 is a program for discharging droplets including a plurality of nozzles arranged in a predetermined direction to discharge a droplet to an object. Corresponding to each nozzle group when dividing the plurality of nozzles into a plurality of nozzle groups so as to include at least one nozzle, and a first control means for controlling the discharge amount of the droplets discharged from On a straight line that is arranged in a direction intersecting with the predetermined direction, passes through the position where the nozzle group is opposed on the object conveyed in the intersecting direction, and extends in the intersecting direction. Light source means comprising a plurality of light source groups including a plurality of light sources that sequentially irradiate light on the droplets on the object that have reached the respective positions at different positions along the predetermined direction. Vomit The amount is intended to function as a second control means for controlling the discharge amount of irradiation energy of each of the light sources constituting the light source groups corresponding to the nozzle group that is controlled.

  According to the invention of claim 1, claim 11 and claim 12, it is possible to dry the droplets efficiently and with low energy without impairing the image quality as compared with the case where the present invention is not applied. An effect can be obtained.

  In addition, according to the second aspect of the present invention, it is possible to obtain a temperature profile that is suitable for drying droplets as compared to the case where the distribution of the temperature of the discharged droplets with respect to the time axis is not formed. The effect is obtained.

  Further, according to the invention described in claim 3, it is possible to obtain a more appropriate temperature profile when drying the droplet, compared to the case where the temperature of the droplet of the present invention does not have a distribution with respect to the time axis. The effect that it can be obtained.

  Further, according to the invention described in claim 4, it is possible to obtain an effect that the rise time of the temperature of the droplet can be further shortened as compared with the case where the configuration of the present invention is not provided.

  Further, according to the invention described in claim 5, it is possible to obtain an effect that the variation in the discharge amount of the droplets can be absorbed more than in the case where the configuration of the present invention is not provided.

  Further, according to the invention described in claim 6, it is possible to obtain an effect that the irradiation energy can be controlled more reliably as compared with the case where lighting and extinguishing are not switched.

  According to the seventh aspect of the invention, an effect is obtained that the irradiation energy can be controlled more easily and reliably as compared with the case where the light intensity of each light source in the light source group is not controlled.

  Further, according to the invention described in claim 8, there is an effect that the irradiation energy can be controlled more accurately than in the case where the number of pulsed light of each light source is not controlled.

  In addition, according to the ninth aspect of the present invention, it is possible to obtain an effect that light can be irradiated more appropriately than in the case where the light source is not a surface emitting laser.

  In addition, according to the invention described in claim 10, it is possible to obtain an effect that the light from the light source can be used more effectively than in the case where the light condensing means of the present invention is not provided.

1 is a front sectional view showing a configuration of an ink jet recording apparatus according to an embodiment. It is a top view which shows the structure of the recording / drying composite head which concerns on embodiment. It is sectional drawing which shows the structure of the recording / drying composite head which concerns on embodiment. It is a block diagram which shows the structure of the drive part of the recording / drying composite head which concerns on embodiment. FIG. 2 is a block diagram illustrating a main configuration of an electric system of the ink jet recording apparatus according to the embodiment. It is a graph which shows the change with respect to time of the temperature of the ink droplet by the light irradiation which concerns on embodiment. It is a graph which shows the difference by the discharge amount of an ink drop of the change with respect to time of the temperature of the ink drop by light irradiation which concerns on embodiment. It is a graph which shows the difference by the light intensity of the change with respect to time of the temperature of the ink droplet by the light irradiation which concerns on embodiment. It is explanatory drawing with which it uses for description of the relationship between the discharge of the ink drop in the recording / drying | combination combined head which concerns on embodiment, and light irradiation by VCSEL. It is explanatory drawing with which it uses for description of light irradiation by the drying head in case the ink droplet which concerns on 1st Embodiment is a large droplet. It is a graph which shows the relationship between the intensity | strength of light and the temperature of an ink drop when the ink drop which concerns on 1st Embodiment is a large drop. It is explanatory drawing with which it uses for description of light irradiation by the drying head in case the ink droplet which concerns on 1st Embodiment is a medium droplet. It is a graph which shows the relationship between the intensity | strength of the light in case the ink droplet which concerns on 1st Embodiment is a medium droplet, and the temperature of an ink droplet. It is explanatory drawing with which it uses for description of light irradiation by the drying head in case the ink droplet which concerns on 1st Embodiment is a small droplet. It is a graph which shows the relationship between the intensity | strength of the light in case the ink droplet which concerns on 1st Embodiment is a small droplet, and the temperature of an ink droplet. It is explanatory drawing with which it uses for description of irradiation of the light by the drying head with respect to the ink droplet row | line | column which concerns on 1st Embodiment. It is explanatory drawing with which it uses for description of the light intensity by each VCSEL with respect to the ink droplet row | line | column which concerns on 1st Embodiment. It is a schematic diagram which shows the structure of LUT for the droplet drying control process which concerns on 1st Embodiment. It is a flowchart which shows the flow of a process of the droplet drying control processing program which concerns on embodiment. It is explanatory drawing with which it uses for description of light irradiation by the drying head in case the ink droplet which concerns on 2nd Embodiment is a large droplet. It is a schematic diagram which shows the relationship between the light irradiation and the temperature of an ink droplet when the ink droplet which concerns on 2nd Embodiment is a large droplet. It is explanatory drawing with which it uses for description of light irradiation by the drying head in case the ink droplet which concerns on 3rd Embodiment is a large droplet. It is sectional drawing which shows the structure of the recording / drying composite head based on 4th Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Here, the case where the present invention is applied to an ink jet recording apparatus that records an image by ejecting ink droplets will be described.

[First Embodiment]
FIG. 1 shows an ink jet recording apparatus 12 according to the present embodiment. A paper feed tray 16 is provided in the lower part of the casing 14 of the ink jet recording apparatus 12, and the sheets P stacked in the paper feed tray 16 are taken out one by one by a pickup roll 18. The taken paper P is transported by a plurality of transport roller pairs 20 constituting a predetermined transport path 22. Hereinafter, the “conveying direction” simply refers to the conveying direction of the paper P that is a recording medium, and the “upstream” and “downstream” refer to upstream and downstream in the conveying direction, respectively.

  Above the paper feed tray 16, an endless transport belt 28 stretched around a drive roll 24 and a driven roll 26 is disposed. A composite head array 30 is disposed above the conveyor belt 28 and faces the flat portion 28F of the conveyor belt 28. This opposed area is an ejection area SE where ink droplets are ejected from the composite head array 30. The sheet P transported along the transport path 22 is held by the transport belt 28 and reaches the discharge area SE, and ink droplets corresponding to image data are attached from the composite head array 30 in a state of facing the composite head array 30. The

  Then, the sheet P is circulated while being held by the conveyor belt 28, thereby allowing the sheet P to pass through the discharge region SE a plurality of times, and so-called multipass image recording is performed.

For example, the transport belt 28 is made of a semiconductive polyimide material (surface resistance value 10 ⁸ to 10 ¹³ Ω / □, volume resistance value 10 ⁹ to 10 ¹⁴ Ω · cm), thickness 75 μm, width 380 mm, circumference What was shaped into a length of 1000 mm is used. As the drive roll 24 and the driven roll 26, for example, a SUS roll having a diameter of 50 mm is used.

  Further, the means for rotating the recording medium is not limited to the conveyance belt 28. For example, the recording medium (paper P) may be sucked and held on the outer periphery of a conveyance roller formed in a cylindrical shape or a columnar shape and rotated. However, since the flat portion 28F is formed when the conveyor belt 28 is used as in the present embodiment, the composite head array 30 can be disposed corresponding to the flat portion 28F, which is preferable.

  In the present embodiment, the composite head array 30 has a long shape in which the effective recording area is equal to or larger than the width of the paper P (the length in the direction orthogonal to the transport direction), and yellow (Y), magenta (M ), Cyan (C), and black (K), four recording / drying composite heads 32 corresponding to each of the four colors are arranged along the transport direction, and a full-color image is recorded. The method for ejecting ink droplets in each recording / drying composite head 32 is not particularly limited, and a known method such as a so-called thermal method or piezoelectric method is applied.

  The operation of each recording / drying composite head 32 is controlled by a composite head controller 78 (see FIG. 5) described later. For example, the composite head controller 78 determines an ink droplet discharge timing and an ink discharge port (nozzle) to be used according to the image data, and sends a drive signal to the recording / drying composite head 32. As the driving method, for example, a matrix driving method is used. The composite head controller 78 further sends a control signal for controlling a light source for drying ink droplets by light irradiation to the recording / drying composite head 32.

  Further, the composite head array 30 may be fixed in a direction orthogonal to the transport direction, but is configured to move as necessary so that a higher resolution image can be obtained by multipass image recording. It may be possible to record or not to reflect the trouble of the combined recording / drying head 32 in the recording result.

  Four maintenance units 34 corresponding to the respective recording / drying composite heads 32 are arranged in the vicinity of the composite head array 30 (in the present embodiment, both sides in the transport direction). When maintenance is performed on the recording / drying composite head 32, the composite head array 30 moves upward, and the maintenance unit 34 moves into the gap formed between the transport belt 28 and enters. Then, a predetermined maintenance operation (vacuum, dummy jet, wiping, capping, etc.) is performed while facing the nozzle surface. Here, the nozzle surface refers to the surface of each recording / drying composite head 32 that faces the flat portion 28F of the conveying belt 28.

  In the present embodiment, the four maintenance units 34 are divided into two sets of two, and are arranged on the upstream side and the downstream side of the composite head array 30 at the time of image recording by the composite head array 30, respectively. Yes.

  On the other hand, a charging roll 36 to which a power source (not shown) is connected is disposed on the upstream side of the composite head array 30. The charging roll 36 is driven while sandwiching the conveyance belt 28 and the paper P with the driven roll 26, and moves between a pressing position for pressing the paper P against the conveyance belt 28 and a separation position separated from the conveyance belt 28. It is possible. At the pressing position, a predetermined potential difference is generated between the grounded driven roll 26 and the sheet P is electrostatically attracted to the transport belt 28 by applying an electric charge to the sheet P.

  A peeling plate 40 is disposed on the downstream side of the composite head array 30, and the paper P is peeled from the transport belt 28. As the peeling plate 40, for example, an aluminum plate having a thickness of 0.5 mm, a width of 330 mm, and a length of 100 mm is used.

  The peeled paper P is transported by a plurality of discharge roller pairs 42 that constitute a discharge path 44 on the downstream side of the peeling plate 40, and is discharged to a paper discharge tray 46 provided on the top of the housing 14.

  A reversing path 52 including a plurality of reversing roller pairs 50 is provided between the paper feed tray 16 and the transport belt 28, and the transport belt is configured to reverse the sheet P on which an image is recorded on one side. 28, the image recording on both sides of the paper P can be easily performed.

  An ink tank 54 is provided between the transport belt 28 and the paper discharge tray 46 to store the four colors of ink. The ink in the ink tank 54 is supplied to the composite head array 30 through an ink supply pipe (not shown). As the ink, various known inks such as water-based ink, oil-based ink, and solvent-based ink are used.

  Next, the configuration of the combined recording / drying head 32 according to the present embodiment will be described with reference to FIGS. FIG. 2 is a plan view of a nozzle surface that is a surface facing the flat portion 28F of the conveyance belt 28 of the combined recording / drying head 32 according to the present embodiment, and FIG. 3 relates to the present embodiment. FIG. 2 is a cross-sectional view of the combined recording / drying head 32 as viewed from a direction perpendicular to the paper surface in FIG.

  As shown in FIG. 2, the combined recording / drying head 32 includes a recording head 100 and a drying head 200. The recording head 100 includes four nozzle arrays 102a, 102b, 102c, and 102d (hereinafter simply referred to as “nozzle array 102” when each nozzle array is not distinguished). It includes four nozzles 104A, 104B, 104C and 104D (hereinafter simply referred to as “nozzle 104” when each nozzle is not distinguished).

  Each nozzle 104 is connected to an ink droplet ejector 130 that is an ink droplet ejection mechanism. FIG. 3 shows an example of a specific configuration of the ink droplet ejector 130 according to the present exemplary embodiment. The ink droplet ejector 130 employs a piezoelectric element (piezo element) 120 as a pressure generating element serving as an actuator. The ink droplet ejector 130 includes a pressure chamber 110, a common electrode (vibrating plate) 122, an individual electrode 124, and a nozzle 104A.

  The piezoelectric element 120 is deformed by a voltage applied from the common electrode 122 and the individual electrode 124 to vibrate the common electrode 122 forming a part of the wall surface of the pressure chamber 110 of the ink droplet ejector 130. At this time, the piezoelectric element 120 deforms the common electrode 122 so that the pressure chamber 110 expands when the voltage of the individual electrode 124 with respect to the common electrode 122 decreases, and the pressure chamber 110 increases when the voltage increases. The common electrode 122 is deformed so as to contract. The ink droplet ejector 130 ejects the ink in the pressure chamber 110 from the nozzle 104 </ b> A as the ink droplet 112 by expanding and contracting the common electrode 122. The piezoelectric element as the actuator is not limited to this example, and one side of the laminate may be a common electrode and the other may be an individual electrode. In addition, the expansion and contraction of the pressure chamber due to the decrease and increase of the potential may be different from those of the present embodiment depending on the polarization direction of the piezoelectric element.

  The configuration of the recording head 100 is not limited to this, and any number of nozzle arrays 102 and 104 may be used, and the arrangement of the nozzle array 102 and nozzle 104 is not limited to a staggered pattern, but may be other arrangements such as a straight line. It may be.

  On the other hand, as shown in FIG. 2, the drying head 200 includes four VCSEL (Vertical Cavity Surface Emitting Laser) arrays 202a, 202b, 202c, and 202d (hereinafter, when each VCSEL array is not distinguished). , Simply referred to as “VCSEL array 202”). Each VCSEL array 202 includes four VCSEL groups 206 including five VCSELs 204A, 204B, 204C, 204D, and 204E (hereinafter, simply referred to as “VCSEL 204” when not distinguishing each VCSEL). A total of 20 VCSELs are arranged in a staggered pattern.

  In the recording head 100 and the drying head 200 configured as described above, each VCSEL group 206 of each VCSEL array 202 that constitutes the drying head 200 with respect to each nozzle 104 of each nozzle array 102 that constitutes the recording head 100. Is configured to correspond in the transport direction of the paper P shown in FIG. In the combined recording / drying head 32 according to the present embodiment, the VCSELs 204A, 204B, 204C, 204D and 204E of the VCSEL group 206 are applied to the ink droplets 112 ejected from the nozzles 104 as shown in FIG. To 210A, 210B, 210C, 210D and 210E (hereinafter referred to simply as “light irradiation 210” when the light irradiation is not distinguished), and the irradiation energy of the light irradiation 210 is controlled and dried. It is configured to let you.

  Next, with reference to FIG. 4, the configuration of the drive units of the recording head 100 and the drying head 200 will be described.

  As shown in FIG. 4, the drive unit of the combined recording / drying head 32 according to the present embodiment includes an image processing unit 302, a quantization unit 304, a nozzle driver 150, and a VCSEL driver 250. The image processing unit 302 and the quantization unit 304 are a part of functions of a CPU 70 (see also FIG. 5) described later, and the nozzle driver 150 and the VCSEL driver 250 are built in the combined recording / drying head 32. The nozzle driver 150 and the VCSEL driver 250 are controlled via a composite head controller 78 (see also FIG. 5) described later when a CPU 70 (see also FIG. 5) described later issues a control command. However, the present invention is not limited to such a configuration. For example, the image processing unit 302 and the quantization unit 304 may be configured by using dedicated hardware such as ASIC (Application Specific Integrated Circuit). Good. Further, the nozzle driver 150 and the VCSEL driver 250 may be provided on the main body side of the inkjet recording apparatus 12 instead of in the combined recording / drying head 32.

Then, image data is input to the image processing unit 302 from a frame memory (not shown) in which the image data to be recorded is written. As image data, for example, data representing each gradation value of red (R), green (G), and blue (B) of each pixel in 256 gradations from 0 to 255 using 8 bits. Is used. However, the gradation value is not limited to 256, and an arbitrary value may be used.
The image processing unit 302 performs resolution conversion processing, color conversion processing, and the like on the input image data, and converts 8-bit R, G, and B image data into 8-bit Y, M, C, and K, respectively. The data is converted into data for each pixel represented by a gradation value.

  The quantization unit 304 compares the data for each pixel represented by the 8-bit Y, M, C, and K gradation values with a threshold value, for example, 2-bit Y, M, C, and K Conversion (quantization) into data represented by each gradation value. The 2-bit gradation value represents one of four values “0”, “1”, “2”, and “3”. “0” represents no ink droplet ejection (discharge amount 0), “1” represents small droplet ejection (small ejection amount), “2” represents medium droplet ejection (medium ejection amount), and “3” "Represents large droplet discharge (large discharge amount). Note that the number of quantization bits is not limited to 2 bits, and an appropriate value may be adopted in a specific application.

The quantized data quantized by the quantizing unit 304 is branched into two, one of which is sent to the nozzle driver 150, and the nozzle driver 150 drives the recording head 100.
In addition, the other of the two branches of the quantized data is sent to the VCSEL driver 250, and the VCSEL driver 250 drives the drying head 200.

  Next, with reference to FIG. 5, the configuration of the main part of the electrical system of the inkjet recording apparatus 12 according to the present embodiment will be described.

  As shown in the figure, the inkjet recording apparatus 12 according to the present embodiment includes a CPU (central processing unit) 70 that controls the operation of the entire apparatus, and a RAM 72 that is used as a work area when various programs are executed. A ROM 74 in which various programs and parameter information are stored in advance, and a non-volatile and rewritable memory 76 are provided. The inkjet recording apparatus 12 includes a composite head controller 78 that controls the operation of the recording / drying composite head 32, and a plurality of motors (not shown) that rotationally drive each part such as the pickup roll 18, the transport roller pair 20, and the drive roll 24. A motor controller 80 for controlling the operation of (omitted) and an external interface 88 for electrically and mechanically connecting an external device such as a personal computer are also provided.

  The CPU 70, RAM 72, ROM 74, memory 76, composite head controller 78, motor controller 80, and external interface 88 are electrically connected to each other via a system bus BUS.

  Therefore, the CPU 70 performs access to the RAM 72, ROM 74, and memory 76, control of the operations of the composite head controller 78 and the motor controller 80, and exchange of various information with an external device via the external interface 88. Is called. In addition to the above configuration, the inkjet recording apparatus 12 according to the present embodiment includes a number of electrical components such as a power supply device that applies a voltage to the charging roll 36. In order to avoid this, these descriptions are omitted.

  In the inkjet recording apparatus 12 of the present embodiment configured as described above, the paper P taken out from the paper feed tray 16 is transported and reaches the transport belt 28 as described above. Then, it is pressed against the conveyor belt 28 by the charging roll 36 and is held by being attracted (contacted) to the conveyor belt 28 by the voltage applied from the charging roll 36. In this state, the paper P passes through the ejection area SE by circulation of the transport belt 28, and the ink droplets 112 are ejected from the composite head array 30, and an image is recorded on the paper P. When recording an image in only one pass, the paper P is peeled from the transport belt 28 by the peeling plate 40, transported by the discharge roller pair 42, and discharged to the paper discharge tray 46. On the other hand, when performing image recording by multi-pass, after the paper P is circulated until it reaches the required number of times and passed through the ejection region SE, the paper P is peeled off from the transport belt 28 by the peeling plate 40, The paper is conveyed by the discharge roller pair 42 and discharged to the paper discharge tray 46.

  By the way, the ink droplet 112 ejected from the nozzle 104 toward the paper P is required to be dried quickly particularly when the ejection amount is large. Adjacent undried ink on the paper P is mixed, causing a decrease in saturation and blurring of the image, and if the undried ink adheres to the conveying roller pair 20 or the like, the paper P or the like becomes dirty. Because there are things.

  Here, let us consider a case where the ink droplets 112 landed on the paper P are dried by a heating source using a light source of a certain intensity, for example, using a light source such as a semiconductor laser. The transition of the temperature of the ink droplet 112 in this case is as shown in FIG. 6 as an example. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates the temperature of the ink droplet 112. In FIG. 6, light irradiation is started at time t <b> 0, and the temperature of the ink droplet 112 that was the initial temperature (discharge temperature) T <b> 0 forms a rising portion with respect to time, and after a certain time t <b> 1 to t <b> 0 has elapsed. At time t1, the ink boiling temperature Tb is reached. The boiling temperature Tb is, for example, 105 ° C.

Thereafter, the boiling temperature Tb is maintained for a time t2-t1 until the water contained in the ink droplet 112 evaporates. At the time t2, when the water contained in the ink droplet 112 has completely evaporated, the boiling temperature Tb can no longer be maintained, and the temperature of the ink droplet 112 rapidly increases. When the temperature of the ink droplet 112 reaches, for example, near 300 ° C. due to the temperature rise after the time t2, the ink droplet 112 is discolored or the portion near the ink droplet 112 of the paper P is burnt and discolored.
Here, for convenience, the region X from time t0 to t1 in FIG. 6 is “temperature rise region”, the region Y from time t1 to t2 is “boiling temperature maintenance region”, and the region Z after time t2 is “temperature rise region”. ".

  Next, when the heating light source having a constant light intensity is irradiated toward the ink droplet 112 as described above, the ejection amount of the ink droplet 112 from the nozzle 104 is large (for example, 10 pL), medium (for example, 7 pL). ) And small (for example, 4 pL). FIG. 7 shows an example of the transition of the temperature of the ink droplets 112 of the respective ejection amounts (represented as “large droplet”, “medium droplet”, and “small droplet” in FIG. 7, respectively).

  In FIG. 7, in the case of a droplet having the smallest water amount compared to other ink droplet discharge amounts, the droplet is heated quickly from the light irradiation start time t0, and the boiling temperature Tb is faster than in the case of other ink droplet discharge amounts. To reach. Also, the evaporation time of moisture is the shortest, and therefore, the moisture is dried fastest, and then the temperature rises rapidly. That is, the gradient of the temperature rising region is the steepest, and the time of the boiling temperature maintaining region is the shortest.

On the other hand, in the case of a large droplet having the largest amount of water compared to other ink droplet ejection amounts, it is overheated most gently from the light irradiation start time t0, and reaches the boiling temperature Tb later than other ink droplet ejection amounts. Since the evaporation time of moisture is the longest, it takes time to dry, and then the temperature rises rapidly. That is, the slope of the temperature rising region is the slowest and the time of the boiling temperature maintaining region is the longest.
In the case of a medium droplet, a temperature profile (characteristic) intermediate between the small droplet and the large droplet is shown.
In addition, the magnitude of the temperature increase gradient in the temperature increase region is in the order of large droplet> medium droplet> small droplet due to the influence of thermal diffusion on the paper P.

Further, with reference to FIG. 8, a case where the light intensity is changed while the ejection amount of the ink droplet 112 is constant will be considered. FIG. 8 shows temporal changes in the temperature of the ink droplet 112 when the light intensity is changed to Pa, Pb, Pc, and Pd with respect to the ink droplet 112 with a constant discharge amount, and Pa>Pb>Pc> Pd. It is.
First, at Pa where the light intensity is maximum, the light power is too strong, and thus overshoot (overshoot) in which the temperature deviates from the boiling temperature Tb occurs in the temperature rising region. In this overshoot portion, the temperature of the ink droplet 112 further rises above the boiling temperature Tb, and the so-called bumping occurs, resulting in a violent boiling, so that the ink droplet 112 scatters around and causes printing deterioration.

  Next, when the light intensity is decreased to Pb, Pc, and Pd, the time of the temperature rising region and the time of the boiling temperature maintaining region are increased accordingly, and the arrival time to the temperature rising region is also increased. In the case of the light intensity Pb, the time of the temperature rising region and the time of the boiling temperature maintaining region are short, and bumping does not occur. Therefore, it can be said to be an ideal temperature profile, but it evaporates even if the boiling temperature maintaining region is too short. Since the accompanying temperature control becomes difficult, it is preferable to form a boiling temperature maintaining region for an appropriate time as in the case where the light intensity is Pc, for example.

  According to the above consideration, when the temperature profile of the ink droplet is taken into consideration, after the light irradiation starts, the temperature rising region is made as short as possible to reach the boiling temperature Tb as quickly as possible, and the temperature rises as close as possible to the temperature rising region. It can be seen that stopping the light irradiation in the boiling temperature maintaining region before reaching the region is ideal for drying the ink droplets. In this way, the ink droplets and the paper P are not discolored, the saturation is not reduced, the image is not blurred, and the paper P is not soiled. Furthermore, since the temperature profile of the ink droplets varies depending on the ejection amount of the ink droplets, it is important to form a temperature profile according to the ejection amount and to form a temperature profile with a boiling temperature maintaining region for an appropriate time. I understand that there is.

Here, Table 1 shows numerical examples of parameters such as the ink droplet ejection amount and the light intensity of the light source. However, these numerical values are merely examples, and for the sake of simplicity, it is assumed that the light intensities from the five light sources arranged per dot are constant.

Table 1 shows that energy E required to dry ink droplets with a maximum ink droplet discharge volume V of 10 pL and 10 pL is ² J / cm ² , the conveyance speed v of the paper P is 500 mm / s, and the light source irradiation width W (in the conveyance direction) 2 shows a calculation example of each parameter based on the premise that the nozzle pitch (see FIG. 2) is 1 mm, the nozzle pitch pitch (see FIG. 2) is 20 μm, and the number of light sources n per dot is five.

According to the above premise, the area S of the irradiation area per dot is S = pitch × W = 20 μm × 1 mm = 0.02 mm ² and the irradiation time t is t = W / v = 1 mm / (500 mm / s). = 2 ms. The energy e supplied to the irradiation area of 1 dot is e = E × S = ( ² J / cm ² ) × 0.02 mm ² = 0.4 mJ, and the required total light intensity P is P = e / t = 0.4 mJ / 2 ms = 200 mW. Therefore, the light intensity P0 per light source element is obtained as P0 = P / n = 200 mW / 5 = 40 mW.

  Next, the operation of the ink jet recording apparatus 12 according to the present embodiment will be described.

FIG. 9 is a diagram schematically showing the relationship between the ejection of the ink droplet 112 in the combined recording / drying head 32 and the light irradiation by the VCSEL 204.
FIG. 9A shows a state immediately after ink droplets 112 are ejected from the nozzle 104 </ b> A toward the paper P and land on the paper P. FIG. Also, in the figure, a VCSEL group 206 including VCSEL 204A to VCSEL 204E corresponding to the conveyance direction of the paper P with respect to the nozzle 104A is shown.

  FIG. 9B shows a state in which the ink droplet 112 is irradiated with pulsed light having the light intensity P0 by the VCSEL 204B as the paper P is conveyed in the direction of the arrow in FIG. Here, positions corresponding to the VCSELs 204A, 204B, 204C, 204D, and 204E on the conveyor belt 28 are denoted as K1, K2, K3, K4, and K5, respectively. Further, the light irradiation when the light of the light intensity Pi is irradiated at the position Kj will be denoted as Pij. In the figure, since the ink droplet 112 has been irradiated with the light having the light intensity P0 at the position K2, it has been irradiated with the light having the light P02.

First, the operation of the drying head 200 according to the present embodiment will be described with reference to FIGS. 10 and 11.
In the present embodiment, each VCSEL 204 of the VCSEL group 206 corresponding to the nozzle 104 is individually controlled in accordance with the amount of ink droplets 112 that have been ejected, and heating is performed by changing temporally the intensity of light to be irradiated. The drying process is configured by the above, and the temperature profile that realizes the appropriate drying described above is formed.

  FIG. 10 shows an example of the state of light irradiation by the VCSEL group 206 when the ink droplet 112 is a large droplet. FIG. 10A shows a state in which the ink droplet 112 on the paper P is receiving the light irradiation P11 having the light intensity P1 at the position K1. Similarly, FIG. 10B shows a state where the ink droplet 112 is irradiated with the light of P12. FIG. 10C shows a state in which the light intensity is changed to P2 smaller than P1, and the ink droplet 112 has received the light irradiation P23. Similarly, in FIGS. 10D and 10E, The state which has received light irradiation P24 and P25 is shown.

  As described above, in the drying head 200 according to the present embodiment, the light intensity of each VCSEL 204 in the VCSEL group 206 is individually controlled to irradiate the ink droplets 112 ejected from the recording head 100 with light. Further, at least one of the VCSELs 204A to VCSEL 204E is turned on in correspondence with the positions K1 to K5.

  FIG. 11 shows the relationship between the light irradiation by the VCSELs 204A to 204E and the temperature of the ink droplet 112. FIG. 11A is a diagram showing the light irradiation P11, P12, P23, P24 and P25 in FIG. 10 in time series, and FIG. 11B shows the temperature of the ink droplet 112 by the light irradiation with respect to time. It is the figure which showed the change.

  As shown in FIG. 11A, in the present embodiment, the light irradiations P11 and P12 having the highest light intensity P1 are applied to the ink droplet 112 at time t0 and time t1. As shown in FIG. 5B, the temperature of the ink droplet 112 reaches the boiling temperature Tb at time tb due to the light irradiation P11 and P12. That is, the time tb-t0 of the temperature rising region is shortened by the light irradiation P11 and P12, and the temperature of the ink droplet 112 quickly reaches the boiling temperature Tb. At this time, the light intensity P1 and the time of the temperature rising region may be set in advance by obtaining a time during which no overshoot occurs by experiments or computer simulations. As described above, bumping occurs when the light intensity P1 is extremely increased, or when the time of the temperature rising region is extremely short.

Further, as shown in FIG. 11A, at the next times t2, t3, and t4, the light irradiations P23, P24, and P25 having the light intensity P2 smaller than the light intensity P1 are applied, and the light irradiation is stopped at the time ts. doing. By these light irradiations, the temperature of the ink droplet 112 is maintained at the boiling temperature for the time ts-tb in the boiling temperature maintaining region, as shown in FIG. As described above, the time ts-tb in the boiling temperature maintaining region is set so that the light irradiation stops before reaching the temperature increasing region. The time for the boiling temperature maintaining region may be set in advance by experiment, computer simulation, or the like, similar to the time for the temperature rising region. By stopping the light irradiation, the temperature of the ink droplet 112 decreases after the time ts. In the figure, the temperature of the ink droplet 112 is shown to be the ejection temperature T0 at the time te, but naturally the temperature at which the ink droplet 112 converges may vary depending on the ambient temperature or the like.
Specific values of the time of the temperature rising region and the time of the boiling temperature maintaining region may be, for example, 0.5 ms to 1 ms and 1 ms to 1.5 ms, respectively.

  FIGS. 12 and 13 show the case where the ink droplet 112 is a medium droplet, and FIGS. 14 and 15 show the VCSEL group 206 of the drying apparatus 200 according to the present embodiment when the ink droplet 112 is a small droplet. The relationship between the light irradiation by each VCSEL 204 and the temperature of the ink droplet 112 is shown.

  In FIG. 12, first, light irradiation P21 and P22 are continuously applied to the ink droplet 112 with light having a light intensity P2 that is relatively weaker than the light intensity P1. Next, light irradiations P33, P34, and P35 are applied to the ink droplet 112 with light having a light intensity P3 that is relatively weaker than the light intensity P2. In this case, the relationship between the time series of the light irradiation pulses in the light irradiation P21, P22, P33, P34 and P35 and the temperature of the ink droplet 112 is as shown in FIG.

  On the other hand, in FIG. 14, first, light irradiations P31 and P32 are continuously applied to the ink droplet 112 with light having a light intensity P3 that is relatively weaker than the light intensity P2. Next, light irradiation P43, P44, and P45 is applied to the ink droplet 112 with light having a light intensity P4 that is relatively weaker than the light intensity P3. In this case, the relationship between the time series of the light irradiation pulses in the light irradiation P31, P32, P43, P44 and P45 and the temperature of the ink droplet 112 is as shown in FIG. The action of each pulse in FIGS. 13A and 15A is the same as that in FIG. 11A in the case of a large droplet.

In the present embodiment, as shown in FIGS. 11, 13 and 15, the profile of the temperature of the ink droplet 112 with respect to the time axis regardless of the ejection amount (large droplet, medium droplet, small droplet) of the ink droplet 112. Are controlled so that each of the VCSELs 204 in the VCSEL group 206 is substantially the same shape. However, the present invention is not limited to this, and the temperature profile of the ink droplet may be varied for each ejection amount of the ink droplet as necessary.
In addition, the temperature profile of the ink droplets varies depending on the type and thickness of the recording medium, as well as the ambient temperature and humidity. Therefore, an optimum temperature profile may be set according to each.

  Here, the parameters in the present embodiment, that is, the light intensities P1, P2, P3, and P4, the pulse widths of the respective irradiation lights, and the like are the LUTs that the CPU 70 refers to in the execution of the droplet drying control processing program by the CPU 70 described later. As (Look Up Table), it may be stored in the ROM 74 in advance.

Next, with reference to FIG. 16 and FIG. 17, irradiation of light of each VCSEL 204 in the drying head 200 to the ink droplet row will be described.
FIG. 16 shows the state of light irradiation of each of the VCSELs 204A to 204E when the ink droplet 112 is ejected with a small droplet 112A, a large droplet 112B, no ink droplet ejection, and a medium droplet 112C to form an ink droplet array. FIG.

  FIG. 16A shows a case where the droplet 112A is positioned immediately below the VCSEL 204A at time t1, and at this time, the VCSEL 204A emits light of light intensity P3. FIG. 16B shows a case where the droplet 112A has moved directly below the VCSEL 204B at time t2, and at this time, the VCSEL 204B emits light having a light intensity P3. On the other hand, the VCSEL 204A is switched to light irradiation with the light intensity P1 because the ink droplet 112 has moved to a large droplet.

  Further, FIG. 16C shows a case where the droplet 112A has moved directly below the VCSEL 204C at time t3. At this time, the VCSEL 204C emits light having a light intensity P4. On the other hand, since the VCSEL 204A has moved to a state without ink droplet ejection, the light irradiation is stopped, and the VCSEL 204B is switched to light irradiation with the light intensity P1. Similarly, FIGS. 16D to 16H show the states from time t4 to time t8, respectively. Here, the time t1 to the time t8 are the switching timing of the light intensity of each VCSEL 204.

  Similarly, as the ink droplet row moves, each of the VCSELs 204A to 204E switches the light intensity according to the ejection amount of the ink droplet 112 that has moved immediately below. If no light irradiation is represented by “0”, the light intensity of the VCSEL 204A changes to (P3, P1, 0, P2, 0, 0, 0, 0). Similarly, the light intensity of the VCSEL 204B changes as (0, P3, P1, 0, P2, 0, 0, 0), and the light intensity of the VCSEL 204C changes to (0, 0, P4, P2, 0, P3, 0). , 0). Further, the light intensity of the VCSEL 204D changes as (0, 0, 0, P4, P2, 0, P3, 0), and the light intensity of the VCSEL 204E is (0, 0, 0, 0, P4, P2, 0, P3).

  FIG. 17 shows how the light intensity in each VCSEL 204 changes with time. FIGS. 17A to 17E correspond to the VCSELs 204A to 204E, respectively. As shown in FIG. 17, the row of light intensity (P3, P1, 0, P2) or the row of light intensity (P4, P2, 0, P3) moves in the transport direction of the paper P along with the change in ejection timing. I will do it.

  By controlling the light irradiation pattern of each VCSEL 204 as described above, a temperature profile corresponding to the ejection amount of ink droplets is formed for large droplets, medium droplets, and small droplets. That is, in FIG. 17, for example, in the case of a droplet, light irradiation with light intensity (P3, P3, P4, P4, P4) is applied from each VCSEL 204A to 204E. It can be seen that this irradiation pattern is the same as the irradiation pattern shown in FIG. Similarly, in the case of a large drop, it is the same as the irradiation pattern shown in FIG. 10, and in the case of a medium drop, it is understood that the irradiation pattern is the same as that shown in FIG.

Next, with reference to FIG. 18 and FIG. 19, the operation of the drying head 200 according to the present embodiment will be described based on the droplet drying control processing program according to the present embodiment.
Here, the inkjet recording apparatus 12 according to the present embodiment executes a droplet drying control process, which is a process for individually controlling each VCSEL 204 of the VCSEL group 206 described above. May be realized by a software configuration using a computer. In addition, the present invention is not limited to the software configuration, and may be realized by, for example, a hardware configuration employing ASIC (Application Specific Integrated Circuit) or a combination of the hardware configuration and the software configuration.

  Hereinafter, a case will be described in which the CPU 70 of the inkjet recording apparatus 12 according to the present embodiment realizes individual control processing for each VCSEL 204 by executing the program. In this case, a form in which the program is installed in the ROM 74 in advance, a form provided in a state stored in a computer-readable storage medium, a form distributed via wired or wireless communication means, etc. are applied. May be.

  First, FIG. 18 shows an example of the LUT used when controlling the VCSEL 204 described above. FIG. 6A shows the light irradiation setting value (light intensity and pulse width of a light pulse, that is, light intensity and pulse width in the present embodiment, for each VCSEL 204 for each ink droplet ejection amount. PLS1, PLS2, PLS3, and PLS4 are shown, and A to E in the figure correspond to VCSEL 204A to VCSEL 204E. There are three types of ink droplet discharge amounts: a large droplet 10 pL, a medium droplet 7 pL, and a small droplet 4 pL.

  FIG. 18B is a table that defines the light intensity and pulse width of each light pulse of the light irradiation set values PLS1, PLS2, PLS3, and PLS4. The light intensities P1 to P4 are P1 in FIG. 10 to FIG. It corresponds to P4.

  In FIG. 18B, for example, PLS1 is an optical pulse having a light intensity P1 = 230 mW (peak value) and a pulse width of 400 μs (half-value width). Thus, for example, in the large drop of FIG. 18 (a), the VCSELs 204A, 204B, 204C, 204D and 204E have optical pulses of 230 mW / 400 μs, 230 mW / 400 μs, 180 mW / 400 μs, 180 mW / 400 μs and 180 mW / 400 μs, respectively. It means that it is set. However, the setting method and setting value in FIG. 18 are merely examples, and in specific application, the light intensity value and the pulse width value may be changed, or the pulse width may be changed for each VCSEL 204.

In this embodiment, the light intensity is defined as a peak value and the pulse width is defined as a half value width. However, the present invention is not limited to this, and the average value and the light intensity peak value are 10 It may be specified by a time width reduced by% or the like.
In this embodiment, the LUT used for controlling the VCSEL 204 is divided as shown in FIGS. 18A and 18B. However, the present invention is not limited to this. 18 (a) and FIG. 18 (b) may be combined, or FIG. 18 (b) may be divided into light intensity and pulse width to form an LUT.

  FIG. 19 is a flowchart showing a processing flow of the droplet drying control processing program according to the present embodiment.

In FIG. 19, when the power of the inkjet recording apparatus 12 is turned on, the CPU 70 first reads the LUT in step S500.
Next, in step S502, ejection data for one dot (ink droplet ejection amount, see FIG. 4) is read. In the next step S504, the LUT is referred to, and an optical pulse pattern corresponding to the ejection amount, that is, VCSEL. The light intensity and pulse width of each VCSEL 204A-204E in group 206 is determined.

In the next step S506, the VCSEL driver 250 (see FIG. 4) that controls the current supplied to each VCSEL 204 of the VCSEL group 206 is controlled, and each VCSEL 204 emits light according to the setting of the LUT (see FIG. 18A). Let
In the next step S508, it is determined whether or not the timing for ending the present droplet drying control processing program has come. If a negative determination is made, the process returns to step S502. The droplet drying control processing program is terminated. The timing at which the droplet drying control processing program is terminated may be, for example, the timing at which a series of printing processes are terminated.

As is clear from the above description, in the recording / drying combined head 32 according to the present embodiment, each VCSEL 204 of the VCSEL group 206 is individually controlled, and is heated by changing temporally the intensity of irradiated light. Thus, the drying process is configured, and a temperature profile that realizes the appropriate drying described above is formed. For this reason, after the start of light irradiation, the temperature rising region is reached as quickly as possible to reach the boiling temperature Tb, and light irradiation is stopped in the boiling temperature maintaining region as close as possible to the temperature rising region and before reaching the temperature rising region.
As a result, in the combined recording / drying head 32 according to the present embodiment, the droplets are efficiently dried with low energy without impairing the image quality.

[Second Embodiment]
In this embodiment, the method for controlling the light irradiation energy of each VCSEL 204 in the first embodiment is changed. In the first embodiment, a method of controlling the light intensity and pulse width of the light pulse is adopted as a method of controlling the light irradiation energy. However, in this embodiment, in each light irradiation, the light pulse is controlled. A method of changing the number is adopted. Note that the pulse width of the light pulse in this embodiment may be set to an appropriate value in relation to the number of light pulses corresponding to each irradiation energy.

FIG. 20 shows a state of light irradiation by the drying head 200 when the ink droplet 112 according to the present embodiment is a large droplet.
In FIG. 20A, five light pulses having a peak value P1 are emitted from the VCSEL 204A at the position K1, and the light irradiation P11 is applied to the ink droplet 112. Similarly, light irradiation P12 is applied from the VCSEL 204B at the position K2.

  Further, at the position K3, three light pulses having a peak value P1 are emitted from the VCSEL 204C, and the light irradiation P23 is applied to the ink droplet 112. Similarly, at positions K4 and K5, light irradiations P24 and P25 are applied from VCSELs 204D and 204E, respectively.

When executing the droplet drying control processing program in the present embodiment, in the LUT shown in FIG. 18, the values of P2, P3 and P4 are set to 230 mW which is the same as P1, and the number of pulses is stored instead of the pulse width. You just have to. In the case of the present embodiment, the number of pulses of PLS1 and PLS2 is 5 and 3, respectively, as described above, and the number of pulses of PLS3 and PLS4 may be 2 and 1 respectively, for example. Therefore, the state of light irradiation when the ink droplet 112 is a medium droplet and a small droplet is obtained by changing the number of pulses in FIG.
The droplet drying control processing program itself is the same as that shown in FIG.

FIG. 21 shows a state of change of the temperature of the ink droplet with respect to time by the light irradiation. Also by the recording / drying combined head 32 according to the present embodiment, each VCSEL 204 of the VCSEL group 206 is individually controlled, and a drying process is configured by heating the irradiation light with a temporal change, A temperature profile is achieved that achieves the proper drying described above.
As a result, even with the combined recording / drying head 32 according to the present embodiment, the droplets are efficiently dried with low energy without impairing the image quality.

  In this embodiment, the light intensity in each light irradiation is set to a constant value P1, and only the number of light pulses is changed. However, the present invention is not limited to this, and the number of light pulses is changed. At the same time, the light intensity may be changed. In other words, the light irradiation control method in the first embodiment may be combined with the light irradiation control method in the second embodiment.

[Third Embodiment]
In the present embodiment, in the light irradiation control of each VCSEL 204 in the first embodiment, the last predetermined number of light pulses in the boiling temperature maintaining region (one in the present embodiment) The strength is weakened.

FIG. 22 shows a state of light irradiation by the drying head 200 when the ink droplet 112 according to the present embodiment is a large droplet.
22 (a) to 22 (d) are the same as FIGS. 10 (a) to 10 (d), but in FIG. 22 (e), the light intensity of FIG. 10 (e) is P2. On the other hand, the light intensity is changed to P3 having a light intensity lower than that of P2.

  In the present embodiment, the influence of variations in the ejection amount of ink droplets is reduced by reducing the light intensity immediately before the end of irradiation. In other words, if the discharge amount of the ink droplets discharged for some reason shifts in a direction that decreases, especially when the boiling temperature maintaining region is set to the middle of the temperature rising region, the temperature rising region is entered, and the ink droplets are discolored. Or the paper P may be burnt. In order to avoid this, the light intensity is decreased for the last one of the light pulses in the boiling temperature maintaining region so that the temperature of the ink droplet does not rise excessively.

  As described above, the combined recording / drying head 32 according to the present embodiment can efficiently dry the droplets with low energy without deteriorating the image quality. In the present embodiment, it is further possible to prevent the temperature of the ink droplet from rising excessively even if the ejection amount of the ink droplet varies.

[Fourth Embodiment]
This embodiment is a form in which a lens is provided corresponding to each VCSEL 204 in the first embodiment.
FIG. 23 shows a cross-sectional view of the combined recording / drying head 400 according to the present embodiment. As shown in FIG. 23, in the present embodiment, condensing lenses 230A, 230B, 230C, 230D, and 230E (hereinafter referred to as “each”) are associated with the light emission surfaces of the VCSELs 204A to 204E included in the drying head 500. If the lenses are not distinguished, they are simply referred to as “lens 230”.

By providing the lens 230, the light from each VCSEL 204 does not diverge, and the condensing diameter of each VCSEL 204 is individually adjusted as necessary.
Furthermore, as shown in FIG. 23, the optical path of the emitted light from each VCSEL 204 may be changed to adjust the irradiation position on the paper as necessary.
In this embodiment, the individual lens 230 is used, but instead of this, a lens-attached VCSEL in which a lens is formed on the light exit surface may be used.

  As described above, even with the combined recording / drying head 400 according to the present embodiment, the droplets are efficiently dried with low energy without deteriorating the image quality. In the present embodiment, the light from the light source is used more effectively.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. Various modifications or improvements can be added to the above-described embodiment without departing from the gist of the invention, and embodiments to which such modifications or improvements are added are also included in the technical scope of the present invention.

  Further, the above embodiment does not limit the invention according to the claims (claims), and all the combinations of features described in the embodiment are essential for the solution means of the invention. Is not limited. The embodiments described above include inventions at various stages, and various inventions are extracted by combining a plurality of disclosed constituent elements. Even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, as long as an effect is obtained, a configuration from which these some constituent requirements are deleted can be extracted as an invention.

  For example, in each of the above embodiments, the present invention has been described by exemplifying an embodiment in which the present invention is applied to an ink jet recording apparatus that forms an image by ejecting ink droplets. However, the present invention is not limited thereto. You may apply to the form to discharge.

  Further, in each of the above-described embodiments, the embodiment in which the number of nozzles is one in the conveyance direction of the recording medium has been described as an example. However, the present invention is not limited to this, and a plurality of nozzles in the conveyance direction. You may apply to the arranged form. Further, in the above-described embodiment, an example in which five light sources are associated with one nozzle has been described. However, the present invention is not limited to this, and the number of light sources to be associated is determined according to the temperature profile of the droplet. It may be set arbitrarily. Furthermore, in each said embodiment, although demonstrated the form which has arrange | positioned 1 row of light sources with respect to a nozzle in the conveyance direction, it was not restricted to this, You may arrange multiple rows.

  In each of the above embodiments, the VCSEL has been described as an example of the light source. However, the present invention is not limited to this, and an edge emitting laser diode, an LED (Light Emitting Diode), or the like may be used. Further, in each of the above-described embodiments, the form in which lighting control is individually performed for the arrayed light sources has been described as an example.

  Further, in each of the above-described embodiments, an example in which the intensity of light emitted from each light source is individually changed has been described. However, the present invention is not limited to this, and a target droplet temperature profile is realized. In this case, the light intensity may be the same for each light source. Further, in each of the above embodiments, the pulsed light irradiation has been described as an example. However, the present invention is not limited to this. If the target temperature profile of the droplet is realized, the light irradiation is performed with a constant intensity. But you can. Further, it is not necessary to stop the light irradiation for each conveyed droplet, and it is possible to keep the light on all the time.

  In each of the above embodiments, the configuration in which the recording head and the drying head are integrated has been described as an example. However, the present invention is not limited to this, and may be configured as a separate body. Even in this case, the same droplet drying control process as that in the above embodiments is applied.

  In each of the above embodiments, various parameters for droplet drying control processing have been illustrated and described as an LUT in advance in the ROM 74. However, this LUT is not necessarily limited to a single one. There is no. A plurality of LUTs are stored in consideration of variations in droplet discharge amount due to conditions such as the type of recording medium, ambient temperature, and humidity, and an optimal combination of parameters is selected according to the conditions. May be. In this case, for example, sensors such as the type of recording medium, ambient temperature, and humidity are provided at appropriate locations in the inkjet recording apparatus 12, and the detection result by the sensor is sent to the CPU 70 and the like. Then, the CPU 70 may select the LUT according to the detection result.

  In addition, the configuration of the ink jet recording apparatus 12 described in the above embodiment (see FIGS. 1 to 5) is merely an example, and unnecessary portions may be deleted or new portions may be removed without departing from the gist of the present invention. And may be added.

  Furthermore, the processing flow of the droplet drying control processing program described in the above embodiment (see FIG. 19) is also an example, and unnecessary steps can be deleted or new steps can be made without departing from the gist of the present invention. May be added or the processing order may be changed.

12 Inkjet recording device 30 Composite head array 32 Recording / drying composite head 70 CPU
72 RAM
74 ROM
78 Combined head controller 100 Recording heads 102a to 102d Nozzle arrays 104A to 104D Nozzle 112 Ink drops 130 Ink drop ejector 150 Nozzle driver 200 Drying heads 202a to 202d VCSEL arrays 204A to 204E VCSELs
206 VCSEL groups 210A to 210E Light irradiation 230A to 230E Lens 250 VCSEL driver 302 Image processing unit 304 Quantization unit
400 Recording / drying combined head 500 Drying head P Paper Pij Light irradiation

Claims (12)

A droplet discharge means including a plurality of nozzles arranged in a predetermined direction for discharging droplets onto an object;
Corresponding to each nozzle group when the plurality of nozzles are divided into a plurality of nozzle groups so as to include at least one nozzle, the nozzles are arranged in a direction intersecting with the predetermined direction and intersecting The droplets on the object that have reached the respective positions at different positions on a straight line that passes through the opposed positions of the nozzle group on the object conveyed in the direction and extends in the intersecting direction. Light source means including a plurality of light source groups including a plurality of light sources that sequentially emit light with respect to the predetermined direction;
Control means for controlling the ejection amount of the droplets and controlling the irradiation energy of each light source constituting the light source group corresponding to the nozzle group for which the ejection amount is controlled according to the ejection amount. Droplet drying device. The droplet drying apparatus according to claim 1, wherein the control unit forms a distribution of the temperature of the droplets with respect to a time axis by controlling irradiation energy of each light source constituting the light source group. The distribution of the temperature of the droplet with respect to the time axis is as follows: a temperature rising region that gradually approaches the boiling temperature of the droplet from a temperature at the time of discharging the droplet after the start of light irradiation from the light source group, and the temperature rising region The droplet drying apparatus according to claim 2, further comprising a boiling temperature maintaining region that maintains the boiling temperature. The droplet drying according to claim 3, wherein the control unit controls the irradiation energy of the light source forming the temperature rising region to be larger than the irradiation energy of the light source forming the boiling temperature maintaining region. apparatus.   The controller is configured such that irradiation energy of a predetermined number of light sources including a light source to be irradiated last or a light source to be irradiated last forms the boiling temperature maintaining region among the light sources forming the boiling temperature maintaining region. The droplet drying apparatus according to claim 3, wherein the droplet drying device is controlled to be smaller than an irradiation energy of another light source. The droplet drying apparatus according to any one of claims 1 to 5, wherein the control unit controls irradiation energy by switching on and off of the light source for each discharged droplet. The droplet drying apparatus according to claim 1, wherein the control unit controls irradiation energy by controlling light intensity of each light source in the light source group. 8. Each light source in the light source group emits pulsed light, and the control means controls irradiation energy by controlling the number of pulsed light of each light source. The droplet drying apparatus according to any one of the above. The droplet drying apparatus according to any one of claims 1 to 8, wherein the light source is a surface emitting laser. 10. The light-emitting device according to claim 1, further comprising a light collecting unit configured to collect light emitted from the light source so as to correspond to a light emission surface of each light source constituting the light source group. Droplet drying device. A droplet drying apparatus according to any one of claims 1 to 10,
Conveying means for conveying a printed material to be dried by the droplet drying apparatus;
A printing apparatus. Computer
A first control unit that controls a discharge amount of the droplets discharged from a droplet discharge unit that includes a plurality of nozzles disposed in a predetermined direction and that discharges the droplets onto the target;
Corresponding to each nozzle group when the plurality of nozzles are divided into a plurality of nozzle groups so as to include at least one nozzle, the nozzles are arranged in a direction intersecting with the predetermined direction and intersecting The droplets on the object that have reached the respective positions at different positions on a straight line that passes through the opposed positions of the nozzle group on the object conveyed in the direction and extends in the intersecting direction. A plurality of light source groups including a plurality of light sources for sequentially irradiating light with respect to the nozzle group, the light source group corresponding to the nozzle group in which the discharge amount is controlled. Second control means for controlling the irradiation energy of each light source according to the discharge amount;
Program to function as.