JP6244953B2 - Drying device, image forming device - Google Patents

Description

  The present invention relates to a drying apparatus and an image forming apparatus.

  In Patent Document 1, a pattern forming method in which a pattern is formed on an object by irradiating laser light onto a region of the liquid droplet that includes a pattern forming material that has landed on the object. It is described that suction is performed at a suction speed corresponding to the drop fluidity.

  Patent Document 2 discloses a printing apparatus that performs printing by ejecting liquid from a liquid ejecting head onto a print medium that is transported by a transport unit, and the transport unit has a suction port for generating negative pressure on a contact surface that contacts the print medium. And a heating means for heating a portion including a portion corresponding to the negative pressure generating suction port of the print medium.

  Patent Document 3 discloses a droplet drying method for a droplet discharge device in which droplets discharged from a discharge head toward a substrate are dried by irradiating a laser beam while flying toward the substrate. A dry gas flows between the nozzle plate of the discharge head and the substrate from a direction perpendicular to the droplet discharge direction, and is opposite to the direction in which the drying gas flows perpendicular to the droplet discharge direction. It is described that the laser beam is irradiated from the direction of the laser beam.

  As a reference, Patent Document 4 discloses that the laser light generating means has a structure that is not easily affected by changes in environmental temperature, and obtains stable quality laser light.

JP 2007-152250 A JP 2008-260207 A JP 2009-072727 A JP 2005-022277 A

  An object of the present invention is to obtain a drying apparatus and an image forming apparatus that can efficiently remove moisture evaporated from droplets on a recording medium from a drying space, as compared with a case without this configuration.

  The invention described in claim 1 is a heat source that evaporates moisture contained in the droplets on the recording medium as opposed to the conveyance path of the recording medium on which an image can be recorded by discharging the droplets from the recording head. An irradiation unit that irradiates laser light; a limiting member that transmits the laser light at a predetermined transmittance; and that restricts the evaporated moisture from reaching the irradiation unit; and heats the limiting member, Dew condensation preventing means for preventing dew condensation on the restricting member.

  The invention according to claim 2 is the invention according to claim 1, wherein the limiting member is a flat plate material that partitions the irradiation unit and the conveyance path, and the laser beam is one surface of the flat plate material. Is transmitted to the other surface and irradiated to the recording medium, and the gas containing moisture evaporated from the recording medium is received by the other surface.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the dew condensation prevention means is provided on the surface of the restricting member and is heated by energy conversion based on electric resistance during energization. This is a conductive film that prevents condensation.

  According to a fourth aspect of the present invention, in the invention of the third aspect, a dielectric film for protecting the conductive film is provided on a surface layer side of the conductive film, and the conductive film and By making the total thickness of the dielectric film a quarter wavelength of the laser beam or an integral multiple thereof, it also serves to prevent reflection.

  According to a fifth aspect of the present invention, in the first or second aspect of the present invention, the dew condensation prevention means is provided on a surface of the restricting member, and receives a part of thermal energy from the laser beam. Thus, the laser light absorption film prevents condensation.

  According to a sixth aspect of the present invention, in the invention of the fifth aspect, the thermal energy due to the irradiation of the laser beam is controlled based on image data for determining an ejection amount of the droplet by the recording head. And a laser light absorbing film that outputs with sufficient thermal energy necessary to evaporate the amount of water on the recording medium determined based on image data and prevent condensation on the restricting member. Is done.

  A seventh aspect of the present invention is the dielectric film according to the fifth or sixth aspect, wherein the limiting member has a dielectric film whose thickness is ¼ wavelength of the laser beam or an integral multiple thereof. The reflection is prevented by the above, and by adding metal ions to the dielectric film, the dielectric film also serves as the laser light absorption film.

  According to an eighth aspect of the present invention, there is provided the drying apparatus according to any one of the first to seventh aspects, and a suction unit that forcibly sucks the gas containing moisture evaporated from the recording medium by the drying apparatus. And an image forming apparatus.

According to the first aspect of the present invention, the water evaporated from the droplets on the recording medium can be efficiently removed from the dry space as compared with the case without this configuration. According to this, it is possible to physically prevent the evaporated water from reaching the irradiation unit and protect the irradiation unit.

  According to the invention described in claim 3, the limiting member can be heated by energization.

  According to the invention described in claim 4, the limiting member can be multifunctional.

  According to the invention described in claim 5, the limiting member can be heated in conjunction with the irradiation of the laser beam.

  According to invention of Claim 6, it can be set as the optimal dry state compared with the case where it does not have this structure.

  According to the seventh aspect of the invention, the dielectric film can be used effectively.

  According to the eighth aspect of the present invention, the water evaporated from the droplets on the recording medium can be efficiently removed from the dry space as compared with the case without this configuration.

1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. (A) is sectional drawing of the glass plate which concerns on 1st Embodiment, (B) is a characteristic view which shows the output wavelength of the laser beam which is a thermal energy source. 6 is a flowchart illustrating a drying control routine when starting a drying unit in the image forming apparatus according to the first embodiment. It is a schematic block diagram of the image forming apparatus which concerns on 2nd Embodiment. (A) is sectional drawing of the glass plate which concerns on 2nd Embodiment, (B) is a characteristic view which shows the output wavelength of the laser beam which is a thermal energy source. 10 is a flowchart illustrating a drying control routine when starting a drying unit in the image forming apparatus according to the second embodiment. FIG. 10 is an enlarged view of a drying unit of an image forming apparatus according to a first embodiment and a second embodiment, showing a modification when a fan mechanism unit for forcibly removing water vapor is attached. It is the modification which concerns on 1st Embodiment and 2nd Embodiment, and is a front view of the drying part using a semiconductor laser. It is the modification which concerns on 1st Embodiment and 2nd Embodiment, and is a front view of the drying part using a semiconductor laser and an optical fiber.

(First embodiment)
FIG. 1 shows an outline of a high-speed aqueous inkjet type image recording apparatus 10 (hereinafter simply referred to as “image recording apparatus 10”) as an image forming apparatus according to the first embodiment.

  In the image recording apparatus 10 according to the first embodiment, an aqueous ink is used and ink is ejected onto the recording medium 12 by a so-called inkjet method to record (print) an image, and at least the ink soaks into the recording medium 12. I try to dry before.

  As shown in FIG. 1, the recording medium 12 is previously wound and loaded in advance in a layered form on the paper feed roller 16 of the paper feed unit 14.

  The recording medium 12 taken up by the paper feed roller 16 is drawn out from the outermost layer of the paper feed roller 16, wound around the plurality of winding rollers 18, and taken up by the take-up roller 22 of the storage unit 20. It is wound up. A motor (not shown) is attached to the winding roller 22 and rotates the winding roller 22 so as to wind the recording medium 12 in layers. That is, the winding roller 22 is a driving roller, and the other rollers are driven rollers.

  A drive roller may be provided by attaching a motor to the paper feed roller 16 or the winding roller 18 and may be wound around the take-up roller 22 while adjusting the tension of the recording medium 12 between the rollers. In this case, a position sensor or a tension sensor that detects slackness of the recording medium 12 may be provided, and the rotation speed (including the rotation direction) of the drive roller may be controlled by each feedback control.

  As shown in FIG. 1, an area where the recording medium 12 is conveyed horizontally and linearly is provided between the pair of winding rollers 18, and this area is an image processing area.

  In the image processing area, an image forming unit 24 and a drying unit 26 are arranged in this order from the upstream side.

  In the image forming unit 24, ink jet heads 28C, 28M, 28Y, and 28K of C (cyan), M (magenta), Y (yellow), and K (black) are arranged. Hereinafter, they are collectively referred to as an inkjet head 28.

  In the ink jet head 28, for example, ink stored in an ink cassette is brought in, and droplets are ejected from the nozzle toward the recording medium 12 facing the nozzle by pressure control, ultrasonic control, or the like. .

  In the image recording apparatus 10 according to the first embodiment, the nozzles are arranged in the entire main scanning direction of the recording medium 12, and the inkjet heads 28 of the respective colors are arranged in the sub-scanning direction of the recording medium 12. The ink droplets corresponding to the image data are ejected from the nozzles of the respective ink jet heads 28 in synchronization with the transport speed.

  The arrangement configuration is not limited, and the inkjet head 28 may be moved in the main scanning direction.

  A drying unit 26 is provided on the downstream side of the image forming unit 24 so that the recording medium 12 on which the image is formed by the image forming unit 24 is opposed to the recording unit 12.

  Here, an image is formed on the recording medium 12 by droplets, but immediately after receiving the droplets from the nozzle, it is in an undried state.

  The purpose of the drying unit 26 is to evaporate the moisture contained in the undried droplets before they are absorbed by the recording medium 12. For this reason, a laser light source is applied as a thermal energy source for drying.

  In the first embodiment, a VCSEL type laser (Vertical Cavity Surface Emitting Laser) is applied as a laser light source. The VCSEL type laser is a vertical cavity surface emitting laser, and has a plurality of (for example, 32) light emitting points on the light emitting surface. In the first embodiment, the VCSEL type laser has 3 as the VCSEL type laser unit 30. The light emitting surface 30 </ b> A is provided, and the light emitting surface 30 </ b> A is opposed to the conveyance path R of the recording medium 12.

  Therefore, the recording surface of the recording medium 12 on which an image is recorded by the image forming unit 24 is opposed to the three light emitting surfaces 30A of the VCSEL laser unit 30, and the light emitting surface 30A of the VCSEL laser unit 30 is being conveyed. The water is evaporated by the thermal energy of the laser beam output from the laser beam.

  That is, in the horizontal and linear conveyance region between the pair of winding rollers 18, an image is recorded by the inkjet head 28 of the image forming unit 24 while the recording medium 12 is linearly conveyed at a constant speed, and The water in the ink is dried by the VCSEL laser unit 30 of the drying unit 26 and reaches the storage unit 20.

  At this time, even if the recording medium 12 is wound around the take-up roller 22 in the storage unit 20 by the immediate drying of the drying unit 26, there is no problem that ink is reflected between the layers.

  Here, the VCSEL laser unit 30 is accommodated in a housing 32 in order to protect it from moisture evaporating from the recording medium 12. A facing surface is opened in the conveyance path R of the recording medium 12 in the housing 32, and a glass plate 34 having a predetermined transmittance is attached. In the first embodiment, the transmittance of the glass plate 34 may be manufactured for the purpose of 100% transmittance with a predetermined allowance, and the allowable range is the VCSEL laser unit 30. What is necessary is just to determine with the drying efficiency by the laser beam output from.

  The water evaporated from the recording medium 12 by the laser light does not reach the VCSEL laser unit 30 by the glass plate 34, and it is possible to prevent the VCSEL laser unit 30 from being damaged by the water.

  On the other hand, if the drying is continued, moisture reaching the glass plate 34 increases and condensation may occur on the glass plate 34. Condensation may prevent the laser light from reaching the recording medium 12.

  Therefore, in the first embodiment, as a means for preventing the condensation of the glass plate 34, the heating film 36 (FIG. 2) is formed on the lower surface of the glass plate 34 (the surface facing the conveyance path R of the recording medium 12). (See (A)).

The heat generating film 36 is a transparent conductive film having an electrical resistance element, and ITO (indium tin oxide), SiC (silicon carbide), and ZnO ₂ (zinc peroxide) can be applied as the material. The definition of “transparent” may be determined by the drying efficiency by the laser light output from the VCSEL laser unit 30 as described above. However, as a result, the film thickness is thin, so that it is determined to be transparent by the naked eye. It is enough to be done.

  Electrodes 38 and 40 are provided on the left and right ends of the heating film 36 in FIG. 1, respectively, and one electrode 38 is connected to a power supply line 44 (voltage + V) via a switch element 42, and the other electrode 40 is grounded. Has been.

  That is, an electric circuit is constructed by the power line 44, the switch element 42, the pair of electrodes 38 and 40, and the heat generating film 36. By applying a voltage to the electrodes 38 and 40, the heat generating film 36 becomes an electric resistance and generates heat. .

  When the heat generating film 36 generates heat, the water evaporated from the recording medium 12 by the laser light from the VCSEL laser unit 30 reaches the glass plate 34, but the glass plate 34 is heated, so no condensation occurs. The water vapor is diffused (released) around the housing 32.

  As shown in FIG. 2A, a dielectric film 46 is further provided on the surface layer side (the lower surface side in FIG. 2A) of the heat generating film 36. As a result, the heat generating film 36 is sandwiched between the glass plate 34 and the dielectric film 46 and is protected from an impact from the outside. Therefore, disconnection or electric leakage is not caused by moisture evaporated from the recording medium 12.

Here, the dielectric film 46 has a function as a protective film for the heat generating film 36 and, in addition, a dielectric (fluoride represented by MgF ₂ and CaF ₂ , oxide represented by SiO ₂ and TiO ₂ ). To prevent reflection (non-reflective coating). The function of preventing the reflection adjusts the film thickness (thickness dimension) of the antireflection coating according to the wavelength of the input light.

  As shown in FIG. 2B, the dielectric film 46 has a total thickness (film thickness) with the heating film 36 in order to have a function of preventing reflection with respect to the wavelength of the input light. Is a quarter wavelength thickness (= λ / 4) of the output wavelength λ of the laser light output from the applied VCSEL laser unit 30.

  The thickness is not limited to λ / 4. If the thickness is an integral multiple of λ / 4, a function of preventing reflection can be provided.

  As shown in FIG. 1, the image recording apparatus 10 is provided with a main control unit 48. The main control unit 48 controls the image forming unit 24 and the drying unit 26 and controls the conveyance of the recording medium 12.

  An image formation control unit 50 is connected to the main control unit 48, and the image data received by the main control unit 48 is sent to the image formation control unit 50 at a predetermined timing.

  The image formation control unit 50 separates the received image data for each color (CMYK) and controls driving of each inkjet head 28.

  The main control unit 48 is connected to a transport system control unit 52. In the transport system control unit 52, motors attached to the respective rollers including the winding roller 22 and position sensors provided on the transport path R of the recording medium 12 are connected, and the recording medium 12 is pulled out from the paper feed roller 16. The winding roller 22 is wound while controlling the tension.

  Further, a reception unit 54 is connected to the main control unit 48. The main control unit 48 outputs an image data output start signal and an end signal to the reception unit 54.

  When receiving the start signal, the reception unit 54 instructs the laser driver 56 to start emission of the VCSEL laser unit 30, and when receiving the end signal, the reception unit 54 instructs the laser driver 56 to end emission of the VCSEL laser unit 30.

  The reception unit 54 is connected to the heating instruction unit 58. The heating instruction unit 58 controls on or off of the switch element 42 that functions as a part of the electric circuit.

  A temperature sensor 60 is attached to the heat generating film 36. The temperature sensor 60 is connected to the temperature monitoring unit 62. Temperature information from the temperature sensor 60 received by the temperature monitoring unit 62 is sent to the heating instruction unit 58.

  The temperature information is, for example, a determination result indicating whether the temperature detected by the temperature sensor 60 is lower than a predetermined target temperature or higher than the target temperature.

  In the heating instruction unit 58, the switch element 42 is turned on by the start signal from the receiving unit 54, the switch element 42 is turned off by the end signal, and the switch element 42 is turned on or off based on the temperature information from the temperature monitoring unit 62. Turn off.

  That is, the heating instruction unit 58 permits heating of the heat generating film 36 during image recording, and controls the switch element 42 to be turned on or off so as to converge within a predetermined temperature range based on the target temperature. It has become.

  Hereinafter, the operation of the first embodiment will be described with reference to the flowchart of FIG.

  FIG. 3 is a flowchart showing a drying control routine when starting the drying unit 26 in the image recording apparatus 10 according to the first embodiment.

  In step 100, it is determined whether or not image recording is started in the image forming unit 24. If the determination is negative, it is not necessary to execute the drying control, and thus this routine ends.

  If an affirmative determination is made in step 100, it is determined that image recording has been started in the image forming unit 24, the process proceeds to step 102, and a light emission start instruction is output to the laser driver 56. When the laser driver 56 receives a light emission start instruction, the laser driver 56 drives the VCSEL laser unit 30 to emit laser light from the light emitting surface 30A.

  The laser light passes through the glass plate 34 and reaches the recording medium 12 on which ink droplets are ejected by the image forming unit 24, and the moisture contained in the ink is evaporated by the thermal energy of the laser light.

  At this time, conveyance of the recording medium 12 is continued, and moisture is evaporated within the range of the light emitting area on the light emitting surface 30A. That is, since the conveyance of the recording medium 12 can be continued, the image recording can be continued in the upstream image forming unit 24.

  In the next step 104, the surface temperature tg of the glass plate 34 is measured by the temperature sensor 60, and the process proceeds to step 106. The measured surface temperature tg is sent to the temperature monitoring unit 62.

  In step 106, the temperature monitoring unit 62 reads the target temperature tm stored in advance, and then in step 108, compares the measured surface temperature tg with the target temperature tm.

  If tg <tm as a result of comparison in step 108, it is determined that the glass plate 34 is not sufficiently heated, and the process proceeds to step 110 where the switch element 42 is turned on to heat the heating film 36. The process proceeds to step 112. As a result, a voltage (+ V) is applied to the heat generating film 36, and the dielectric becomes an electric resistance to generate heat.

  Here, the water evaporated from the recording medium 12 reaches the glass plate 34 and is released from the space along the transport path R to the outside of the drying unit 26. When the amount of water exceeds an allowable value, condensation occurs on the glass plate 34. There is a case.

  Therefore, in the first embodiment, the heating film 36 coated on the glass plate 34 is energized and heated. For this reason, in the glass plate 34, it is prevented that dew condensation occurs due to moisture evaporated from the recording medium 12.

  In step 112, it is determined whether or not the image recording is completed. If the determination is negative, the process returns to step 104 to repeat the above affirmation. If an affirmative determination is made in step 112, there is no need for drying, so the process proceeds to step 114, the switch element is turned off to release heat, and the process proceeds to step 120.

  If tg ≧ tm as a result of the comparison in step 108, it is determined that the glass plate 34 is sufficiently heated, and the process proceeds to step 116 to switch off the heating of the heat generating film 36. 42 is turned off and the routine proceeds to step 118. As a result, no voltage (+ V) is applied to the heat generating film 36 and no heat is generated (with residual heat).

  In step 118, it is determined whether or not the image recording is completed. If the determination is negative, the process returns to step 104 to repeat the above affirmation. On the other hand, if the determination in step 118 is affirmative, there is no need for drying and the switch element 42 is currently off.

  In step 120, the laser driver 56 is instructed to end light emission, and this routine ends.

  Note that the light emission end instruction may be issued after a certain time delay from the end of image recording in consideration of the transport time between the image forming unit 24 and the drying unit 26. Similarly, the heat generation of the heat generating film 36 may be after the switch element 42 is turned off in step 114 after a predetermined time delay from the end of image recording.

(Second Embodiment)
FIG. 4 shows an image recording apparatus 10A according to the second embodiment. Note that the same components as those of the image recording apparatus 10 described in the first embodiment are denoted by the same reference numerals, and description of the configuration is omitted.

  In the second embodiment, as shown in FIG. 5A, reflection is prevented on the surface of the glass plate 34 attached to the opening of the housing 32 (the side facing the conveyance path R of the recording medium 12). The dielectric film 70 having both a function and a laser light absorption function is coated.

As shown in FIG. 5B, the dielectric film 70 is made of a fluoride represented by MgF ₂ and CaF ₂ , and an oxide represented by SiO ₂ and TiO ₂ , as in the first embodiment. Although generated, in the second embodiment, metal ions represented by iron, copper, chromium, tin, and nickel are further added. This metal ion receives a part of the laser beam and absorbs thermal energy to generate heat.

  The addition of metal ions causes the metal ions to be taken into the film components at the same time when the dielectric film 70 is formed by means of sputtering vapor deposition or electron beam vapor deposition. Alternatively, it can be realized by mixing the raw material when forming the vapor deposition source in advance.

  The addition amount of metal ions is several tens to several thousand ppm, and varies depending on the material to be combined and the wavelength of the laser beam.

  In addition, the dielectric film 70 has a thickness (film thickness) of laser light output from the applied VCSEL laser unit 30 in order to have a function of preventing reflection with respect to the wavelength of the input light. The thickness of the output wavelength λ is ¼ wavelength (= λ / 4).

  The thickness is not limited to λ / 4. If the thickness is an integral multiple of λ / 4, a function of preventing reflection can be provided.

  In the second embodiment, the laser light emitted from the VCSEL laser unit 30 is mainly based on image data of an image formed by the image forming unit 24 for the purpose of energy saving measures and overdrying prevention measures. The strength is adjusted so that the thermal energy is necessary and sufficient for drying from the recording medium 12 and preventing condensation generated on the glass plate 34. The intensity of the laser beam does not impair the drying function and the anti-condensation function even if it is fixed at a necessary and sufficient heat energy or higher.

  As shown in FIG. 4, a reception unit 54 is connected to the main control unit 48. The main control unit 48 outputs image data to the receiving unit 54.

  The receiving unit 54 is connected to the intensity calculating unit 72 and outputs the received image data to the intensity calculating unit 72. The intensity calculation unit 72 calculates the intensity of the laser light output from the VCSEL laser unit 30 based on the image data (ink amount), and outputs to the laser driver 56 emission start and end signals of the VCSEL laser unit 30 and the laser. Output light intensity information. The laser driver 56 controls light emission of the VCSEL laser unit 30.

  The operation of the second embodiment will be described below with reference to the flowchart of FIG.

  FIG. 6 is a flowchart showing a drying control routine when starting the drying unit 26 in the image recording apparatus 10A according to the second embodiment.

  In step 150, it is determined whether or not image recording is started in the image forming unit 24. If the determination is negative, it is not necessary to execute the drying control, and thus this routine ends.

  If an affirmative determination is made in step 150, the process proceeds to step 152, and the image data received by the receiving unit 54 and sent to the intensity calculating unit 72 is analyzed.

  In the next step 154, the intensity calculation unit 72 calculates the necessary thermal energy by the laser beam based on the image data, and then proceeds to step 156, where the VCSEL type laser unit is calculated based on the calculated thermal energy. 30 is caused to emit light, and the process proceeds to step 158.

  The required thermal energy is the total thermal energy of thermal energy for evaporating moisture from the recording medium and thermal energy for maintaining the glass plate 34 at a temperature at which no condensation occurs.

  When laser light is irradiated from the VCSEL laser unit 30, the laser light passes through the glass plate 34 and reaches the recording medium 12, and the moisture contained in the ink is evaporated by the thermal energy of the laser light.

  Here, the water evaporated from the recording medium 12 reaches the glass plate 34 and is released from the space along the transport path R to the outside of the drying unit 26. When the amount of water exceeds an allowable value, condensation occurs on the glass plate 34. There is a case.

  Therefore, in the second embodiment, the dielectric film 70 coated on the glass plate 34 is provided with a laser light absorption function, and the glass plate 34 is heated with heat energy generated by absorbing a part of the laser light. I made it. For this reason, in the glass plate 34, it is prevented that dew condensation occurs due to moisture evaporated from the recording medium 12.

  In step 158, it is determined whether or not the image recording is completed. If the determination is negative, the process returns to step 152 to repeat the above affirmation. That is, the intensity of the laser beam is controlled so as to be linked to the image recording process in the image forming unit 24, and the scanning line is irradiated with sufficient and sufficient thermal energy.

  If the determination in step 158 is affirmative, the image recording is completed and there is no need for drying. Therefore, the process proceeds to step 160, the laser driver 56 is instructed to end the light emission, and this routine ends.

  In the first embodiment and the second embodiment described above, it is assumed that the water evaporated from the recording medium 12 is released from the drying unit 26 by a natural air flow, but is shown in FIG. As shown, the suction fan mechanism 74 is provided adjacent to the drying unit 26, and the suction port of the suction nozzle 74A is disposed along the conveyance path R of the recording medium 12, thereby forcibly evaporating the evaporated water. , May be released.

  In this case, it is possible to bring about an energy saving effect by reducing the heat energy for heating the glass plate 34 according to the suction function.

  In the first embodiment and the second embodiment, the VCSEL laser unit 30 is applied as the laser light source of the drying unit 26. However, as shown in FIGS. 76 may be used.

  In FIG. 8, the laser beam output from the semiconductor laser 76 is applied to the recording medium 12 via the lens 78 and the glass plate 34.

  In FIG. 9, the semiconductor laser 76 is disposed remotely with respect to the drying unit 26. In other words, the laser light output from the semiconductor laser 76 is collected by the lens 80, guided using the optical fiber 82, and irradiated onto the recording medium 12 through the lens 84 and the glass plate 34.

DESCRIPTION OF SYMBOLS 10 Image recording device 12 Recording medium 14 Paper feed part 16 Paper feed roller 18 Winding roller 20 Storage part 22 Winding roller 24 Image formation part 26 Drying part 28 (CMYK) Inkjet head 30 VCSEL type laser unit 30A Light emission surface 32 Housing 34 Glass plate 36 Heat generation film 38, 40 Electrode 42 Switch element 44 Power supply line 46 Dielectric film 48 Main control unit 50 Image formation control unit 52 Transport system control unit 54 Reception unit 56 Laser driver 58 Heating instruction unit 60 Temperature sensor 62 Temperature monitoring unit DESCRIPTION OF SYMBOLS 70 Dielectric film 72 Intensity calculating part 74 Suction fan mechanism part 74A Suction nozzle 76 Semiconductor laser 78 Lens 80 Lens 82 Optical fiber 84 Lens

Claims (8)

An irradiation unit that irradiates a laser beam serving as a heat source that evaporates water contained in the droplets on the recording medium, opposed to a conveyance path of a recording medium on which an image can be recorded by discharging the droplets from the recording head;
A limiting member that transmits the laser light at a predetermined transmittance and restricts the evaporated water from reaching the irradiation unit;
Condensation prevention means for heating the restriction member to prevent condensation on the restriction member;
Having a drying device. The limiting member is a flat plate that partitions the irradiation unit and the conveyance path,
2. The laser beam according to claim 1, wherein the laser beam is transmitted from one surface of the flat plate to the other surface and irradiated to the recording medium, and gas containing moisture evaporated from the recording medium is received by the other surface. Drying equipment. The dew condensation preventing means
The drying device according to claim 1, wherein the drying device is a conductive film that is provided on a surface of the restricting member and is heated by energy conversion based on an electric resistance during energization to prevent condensation. On the surface layer side of the conductive film, a dielectric film for protecting the conductive film is provided,
4. The drying apparatus according to claim 3, wherein the total thickness of the conductive film and the dielectric film is set to a quarter wavelength of the laser beam or an integral multiple of the laser light, thereby serving as a function of preventing reflection.   3. The drying according to claim 1, wherein the dew condensation preventing means is a laser light absorption film that is provided on a surface of the restricting member and receives a part of heat energy from the laser light to prevent dew condensation. apparatus. Based on the image data for determining the ejection amount of the droplets by the recording head, further has a control means for controlling thermal energy by the irradiation of the laser light,
6. The drying according to claim 5, wherein the laser light absorbing film is output with heat energy necessary and sufficient to evaporate a moisture amount on a recording medium determined based on image data and prevent condensation on the restricting member. apparatus.   The limiting member is subjected to prevention of reflection by a dielectric film whose thickness is ¼ wavelength of the laser beam or an integral multiple thereof, and by adding metal ions to the dielectric film, The drying apparatus according to claim 5 or 6, wherein the dielectric film also serves as the laser light absorption film. The drying apparatus according to any one of claims 1 to 7,
Suction means for forcibly sucking gas containing moisture evaporated from the recording medium by the drying device;
An image forming apparatus.

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