Drying device and image forming system

Abstract

To provide a drying device capable of adjusting a level of drying according to a state of a medium.SOLUTION: A drying device according to the present invention is a drying device for drying a medium while carrying the medium on which an image is formed by ink. The drying device includes: a conveying unit for conveying the medium in a predetermined conveying direction; a heating unit 23 for supplying energy to the image to dry the image; measuring units 11 and 91 for measuring values related to an amount of water contained in the medium; and a control unit 95 for estimating the amount of water contained in the medium on the basis of the values measured by the measuring units 11 and 91 and controlling at least one of the conveying unit and the heating unit 23 so as to change an amount of energy received by the image in accordance with the estimated amount of water.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a drying device that dries a recording medium on which an image has been formed with ink while conveying the recording medium, and to an image forming system that includes the drying device. [Background technology]

[0002] 2. Description of the Related Art Image forming systems including inkjet image forming apparatuses are provided with a drying device that dries an image formed on a recording medium such as paper.

[0003] The drying device irradiates light onto the image (ink) on the medium, and the energy generated by the ink absorbing the light evaporates the water contained in the ink, thus drying the image. To satisfy the transportability of the medium and the quality of the image, it is necessary to keep the drying to a specified level and prevent insufficient or excessive drying. For example, insufficient drying can cause the ink to transfer to the parts that come into contact with the printing surface, and the transferred ink can then transfer to the medium, causing offset or bleeding. Moreover, excessive drying can cause the medium to yellow or curl, leading to clogging of the medium and unnecessary consumption of electricity.

[0004] To address this issue, the user must adjust the drying device while performing test printing so as to obtain a level of drying of the medium appropriate for the printing purpose, which requires a lot of time and effort to make the adjustments.

[0005] Patent Document 1 discloses a recording device that controls the amount of heat from a heat source according to the amount of black parts in the recording data, and Patent Document 2 discloses an inkjet recording device that heats an ink application part according to a paper size. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 8-142319 [Patent Document 2] Japanese Patent Application Publication No. 9-314818 Summary of the Invention [Problem to be solved by the invention]

[0007] However, in Patent Documents 1 and 2, no consideration is given to adjusting the level of drying, and it is difficult to solve the problems of offset, curl, and the like as described above.

[0008] SUMMARY OF THE PRESENT DISCLOSURE In consideration of the above circumstances, an object of the present invention is to provide a drying device and an image forming system that are capable of adjusting the level of drying depending on the condition of a medium. [Means for solving the problem]

[0009] In order to achieve the above-mentioned object, the drying device of the present invention is a drying device that dries a medium on which an image is formed with ink while transporting it, and is characterized in that it comprises a transport unit that transports the medium in a predetermined transport direction, a heating unit that supplies energy to the image to dry the image, a measurement unit that measures a value related to the amount of moisture contained in the medium, and a control unit that controls at least one of the transport unit and the heating unit to estimate the amount of moisture contained in the medium based on the value measured by the measurement unit and change the amount of energy received by the image in accordance with the estimated moisture amount.

[0010] In the drying device of the present invention, the control unit may be characterized in that it compares the estimated moisture amount with a predetermined moisture amount, and if the estimated moisture amount is greater than the predetermined moisture amount, it controls at least one of the conveying unit and the heating unit so as to increase the amount of energy received by the image.

[0011] In the drying device of the present invention, the heating section may include a plurality of heaters that can be turned on and off individually and are turned on and off at a predetermined frequency, and the control section may be characterized in that when the estimated moisture content is greater than the predetermined moisture content, the control section extends the turn-on time of the plurality of heaters beyond the standard turn-on time.

[0012] In the drying device of the present invention, the plurality of heaters may be arranged side by side in the transport direction, and the control unit may alternately turn on and off adjacent heaters.

[0013] In the drying device of the present invention, the multiple heaters may be arranged in a lattice pattern lined up in the transport direction and a width direction intersecting the transport direction, and the control unit may be configured to alternately turn on and off the heaters adjacent to each other in the transport direction and the width direction.

[0014] In the drying device of the present invention, the heating unit may be equipped with a heater that radiates light, and the control unit may be characterized in that when the estimated moisture content is greater than the predetermined moisture content, the heating unit is controlled to make the wavelength of the light shorter than the standard wavelength.

[0015] In the drying device of the present invention, the control unit may be characterized in that when the estimated moisture content is greater than the specified moisture content, the control unit controls the conveying unit to make the conveying speed of the medium slower than the standard conveying speed.

[0016] In the drying device of the present invention, the conveying unit or the heating unit may be movable so that the distance between the conveying unit and the heating unit can be changed, and the control unit may be configured to move the conveying unit or the heating unit so that the distance between the conveying unit and the heating unit is shorter than the standard distance when the estimated moisture content is greater than the specified moisture content.

[0017] In the drying device of the present invention, the measurement unit may be a humidity sensor that detects ambient humidity, and the control unit may be characterized in that when the ambient humidity detected by the humidity sensor is higher than standard humidity, the control unit estimates that the amount of moisture contained in the medium is greater than the specified moisture amount.

[0018] In the drying device of the present invention, the measurement unit may be a sensor that detects the thickness of the medium, and the control unit may be characterized in that, when the thickness detected by the sensor is thicker than a standard thickness, the control unit estimates that the amount of moisture contained in the medium is greater than the specified moisture amount.

[0019] In the drying device of the present invention, the measurement unit may be a counting unit that calculates the amount of ink, and the control unit may be characterized in that when the amount of ink calculated by the counting unit is greater than a standard amount, the control unit estimates that the amount of moisture contained in the medium is greater than the specified moisture amount.

[0020] The image forming system of the present invention is characterized by comprising an image forming device that forms an image on a medium, and a drying device that dries the medium on which the image has been formed by the image forming device while transporting the medium. Effect of the Invention

[0021] According to the present invention, when the amount of moisture contained in the paper is greater than a predetermined amount, the amount of energy received by the image (ink) is increased, so that the image with a high moisture content can be dried appropriately and yellowing and curling can be prevented. [Brief description of the drawings]

[0022] [Figure 1] 1 is a perspective view showing a schematic diagram of an image forming system according to an embodiment of the present invention; [Diagram 2] 1 is a front view showing the inside of a drying device according to an embodiment of the present invention. [Figure 3A] FIG. 2 is a plan view showing a heater of a heating unit in the drying device according to one embodiment of the present invention. [Figure 3B] FIG. 2 is a plan view showing a heater of a heating unit in the drying device according to one embodiment of the present invention. [Figure 4] 2 is a block diagram showing a control unit of the drying device according to the embodiment of the present invention. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An image forming system and a drying device according to an embodiment of the present invention will now be described with reference to the drawings.

[0024] First, an image forming system including a drying device will be described with reference to Fig. 1. Fig. 1 is a perspective view showing the image forming system. L, R, Fr, and Rr appropriately attached to each figure indicate the left side, right side, front side, and rear side of the image forming system, respectively.

[0025] The image forming system 1 includes a paper feeder 3, an image forming device 5, a drying device 7, and a post-processing device 9. The paper feeder 3 stores paper and feeds the paper to the image forming device 5. The image forming device 5 is disposed to the left of the paper feeder 3, and forms an image on the paper fed from the paper feeder 3 by an inkjet method, for example, based on image data input from an external computer. The drying device 7 is disposed to the left of the image forming device 5, and dries the paper on which an image has been formed while transporting it. The post-processing device 9 is disposed to the left of the drying device 7, and performs post-processing on the paper dried by the drying device 7. Paper is an example of a medium of the present invention.

[0026] The image forming system 1 also includes an ultrasonic sensor 11 (see FIG. 4) that detects the thickness of the paper on which an image is formed. The ultrasonic sensor 11 is, for example, a transmission type sensor having a transmitter and a receiver that are arranged with an object to be detected (paper in this example) between them. The receiver receives ultrasonic waves transmitted from the transmitter, and detects the thickness of the paper based on the amount of transmitted ultrasonic waves. The ultrasonic sensor 11 is included in, for example, the paper feeder 3 or the image forming device 5.

[0027] Next, the drying device 7 will be described with reference to Fig. 2, Fig. 3A, Fig. 3B, and Fig. 4. Fig. 2 is a front view showing the inside of the drying device. Figs. 3A and 3B are plan views showing the heater of the heating unit. Fig. 4 is a block diagram showing the control unit of the drying device 7.

[0028] The drying device 7 includes a box-shaped housing 21. The housing 21 has a rectangular parallelepiped hollow portion surrounded by a top plate, a bottom plate, front and rear side plates, and left and right side plates. A heating unit 23, a conveying unit 25, and a suction unit 27 are accommodated on the image forming device 5 side (right side) of the hollow portion. A cooling unit 29 is accommodated above the post-processing device 9 side (left side) of the hollow portion of the housing 21.

[0029] An inlet 31 is formed at the top of the right side panel (the side panel on the side of the image forming device 5) of the housing 21, through which paper (medium) is received from the image forming device 5. An outlet 33 is formed at the top of the left side panel (the side panel on the side of the post-processing device 9) through which paper is passed to the post-processing device 9. The paper is transported by the transport section 25 and the cooling section 29 along the transport direction X from the inlet 31 to the outlet 33. In the following description, the upstream side and the downstream side respectively refer to the upstream side and the downstream side in the transport direction X of the paper. The direction perpendicular to the transport direction X is defined as the width direction Y.

[0030] Next, a description will be given of the heating section 23. The heating section 23 includes a plurality of blower fans 41, a heater unit 43, and a case 45 in which the plurality of blower fans 41 are supported and in which the heater unit 43 is housed.

[0031] The case 45 is formed in a box shape with an open bottom, and has a hollow portion that is long in the conveying direction and is surrounded by a top plate, front and rear side plates, and left and right side plates. A plurality of exhaust ports (not shown) are formed in the top plate. An exhaust fan 49 is connected to each exhaust port via a duct 47. When each exhaust fan 49 is driven, the air inside the case 45 is exhausted, and the air in the hollow portion of the case 45 is circulated.

[0032] The plurality of blower fans 41 are supported on an upper plate of the case 45. The plurality of blower fans 41 take in outside air and blow the taken-in outside air into the hollow portion of the case 45.

[0033] The heater unit 43 includes a plurality of infrared heaters 51 and a housing 53 in which the plurality of heaters 51 are housed.

[0034] The housing 53 is formed in a box shape with an open bottom and has a hollow portion that is long in the conveying direction and is surrounded by a top plate, front and rear side plates, and left and right side plates. A large number of through holes are opened over the top plate.

[0035] Each heater 51 has, for example, a thin carbon filament and a glass tube in which the filament is housed. The filament radiates light (infrared rays) in all radial directions (360 degrees). As shown in Fig. 3A, the heaters 51 are arranged side by side at equal intervals along the conveying direction X in a position along the width direction Y. The heaters 51 can be turned on and off individually.

[0036] Next, the conveying section 25 will be described. The conveying section 25 includes a conveying belt 61 and a frame 63 that supports the conveying belt 61. The frame 63 has front and rear side plates that are long in the conveying direction X and are arranged at a predetermined interval in the front-rear direction. A driving roller 65 is rotatably supported between the upstream ends of the front and rear side plates, and a driven roller 67 is rotatably supported between the downstream ends.

[0037] The conveyor belt 61 is an endless belt, and has a large number of through holes (not shown) formed on the entire surface. The conveyor belt 61 is wound around a driving roller 65 and a driven roller 67. The driving roller 65 is connected to a conveyor motor 69 (see FIG. 4). The driving roller 65 is driven and rotated by the conveyor motor 69, so that the conveyor belt 61 runs in a counterclockwise direction in FIG. 2 at a preset standard speed. The outer surface of the conveyor belt 61 along the upper track (direction from the upstream side to the downstream side) becomes the conveyor surface 61a along which the paper is conveyed. The interval between the conveyor surface 61a and the heating unit 23 is preset to a standard interval. The conveyor belt 61 running on the upper track is supported by a conveyor plate 71 supported by front and rear side plates. The conveyor plate 71 has through holes formed on the entire surface. When the conveyor belt 61 runs, the back surface of the conveyor belt 61 (the surface behind the conveyor surface 61a) running on the upper track slides along the conveyor plate 71.

[0038] The conveying section 25 is formed to be longer upstream in the conveying direction X than the heating section 23. In detail, the upstream end of the conveying surface 61a of the conveying belt 61 extends upstream of the upstream end of the heating section 23 and upstream of the receiving port 31. The downstream end of the conveying surface 61a is located at approximately the same position as the downstream end of the heating section 23 and communicates with the cooling section 29.

[0039] The frame 63 is supported by the housing 21 so as to be movable up and down. A lifting motor 73 (see FIG. 4) is connected to the frame 63 via, for example, a winding roller or a pulley (both not shown). By driving the lifting motor 73, the conveying unit 25 is lowered from a conveying position where the conveying surface 61a faces the heating unit 23 at a standard distance to a retracted position where the conveying surface 61a is lowered from the heating unit 23 by a distance equal to or greater than the standard distance. By lowering the conveying unit 25 to the retracted position, it is possible to handle paper jams that occur on the conveying surface 61a. A description of the mechanism for lifting and lowering the conveying unit 25 will be omitted.

[0040] Next, the suction unit 27 will be described. The suction unit 27 is provided in the hollow portion of the conveyor belt 61. The suction unit 27 includes a partition plate 81 and a plurality of suction fans 83 (three in this example) supported by the partition plate 81. The partition plate 81 has a bottom plate and partition walls surrounding the four sides, and divides the hollow portion into a plurality of compartments (three in this example) along the conveying direction X. The upper surface of each compartment is open and faces the conveying plate 71.

[0041] The suction fans 83 are attached to the bottom plate of the partition plate 81 in correspondence with each compartment. The suction fans 83 have the same air volume. When the suction fans 83 are driven, air in the space above the conveyor belt 61 (conveyor surface 61a) traveling on the upper track is taken into each compartment through the through holes of the conveyor belt 61 and the through holes of the conveyor plate 71.

[0042] Furthermore, a humidity sensor 91 is provided inside the housing 21 of the drying device 7. In this example, the humidity sensor 91 is provided inside the case 45 of the heating unit 23.

[0043] Next, the control unit 95 of the image forming system 1 will be described with reference to Fig. 4. The control unit 95 is electrically connected to the ultrasonic sensor 11 and the humidity sensor 91. The detection results of the ultrasonic sensor 11 and the humidity sensor 91 are transmitted to the control unit 95. Furthermore, the control unit 95 includes a counting unit that counts the cumulative value of dots constituting the image data formed in the image forming device 5. The ultrasonic sensor 11, the humidity sensor 91, and the counting unit (controller 95) are an example of a measurement unit that measures a value related to the amount of moisture contained in paper.

[0044] Furthermore, the control unit 95 is electrically connected to the heating unit 23 to individually turn on and off each heater 51. The control unit 95 can also change the on and off times of each heater 51.

[0045] Furthermore, the control unit 95 is electrically connected to the conveying motor 69 of the conveying unit 25, and controls the rotation speed of the drive roller 65 to cause the conveying belt 61 to travel at a predetermined conveying speed or a speed slower than the predetermined conveying speed.

[0046] Furthermore, the control unit 95 is electrically connected to the lifting motor 73 of the transport unit 25, and controls the rotation direction and rotation time of the lifting motor 73 to lift and lower the transport unit 25 (frame 63) between the transport position and the retracted position. The control unit 95 can also drive the lifting motor 73 to lower the transport unit 25 to a predetermined position between the transport position and the retracted position, or to lift the transport unit 25 to be closer to the heating unit 23 than the transport position. At the transport position, the distance between the transport unit 25 and the heating unit 23 is set wider than the predetermined distance. A position closer to the heating unit than the transport position is a position where the paper is not excessively heated.

[0047] An example of the drying operation of the drying device 7 having the above configuration will be described mainly with reference to Figures 2 to 4. A sheet of paper on which an image has been formed by the image forming device 5 (see Figure 1) is received by the conveying section 25 through the receiving port 31 of the drying device 7. As described above, since the upstream end of the conveying surface 61a of the conveyor belt 61 extends upstream of the receiving port 31, the sheet of paper discharged from the image forming device 5 is placed on the conveying surface 61a of the conveyor belt 61.

[0048] The control unit 95 drives the conveyor motor 69 at a predetermined rotation speed to rotate the drive roller 65 and move the conveyor belt 61. As a result, the paper placed on the conveyor surface 61a is conveyed through the receiving opening 31 into the inside of the housing 21.

[0049] Furthermore, the blower fan 41 of the heating section 23 is driven. The air taken into the hollow section of the case 45 by the blower fan 41 is blown downward and enters the housing 53 of the heater unit 43.

[0050] Furthermore, the suction fan 83 of the suction unit 27 is driven. As a result, as described above, air in the space above the conveyor belt 61 traveling on the upper track is taken in through each section via the through holes of the conveyor belt 61 and the through holes of the conveyor plate 71, and negative pressure is created above the conveyor surface 61a. Then, the paper conveyed on the conveyor surface 61a of the conveyor belt 61 is attracted to the conveyor surface 61a.

[0051] The control unit 95 estimates the amount of moisture contained in the paper from the detection results of the ultrasonic sensor 11 and the humidity sensor 91 and the amount of ink calculated by the counting unit. Specifically, the control unit 95 compares the sound wave intensity received by the ultrasonic sensor 11 with a standard sound wave intensity for paper of a preset thickness, and estimates that the amount of moisture contained in the paper is greater than a predetermined amount if the detected sound wave intensity is lower than the standard sound wave intensity. The standard sound wave intensity is, for example, the sound wave intensity when the ultrasonic sensor 11 detects a sheet of paper set in the image forming system 1. The predetermined amount of moisture is, for example, the amount of moisture when the paper is dried without offset or curling. This method is called the first estimation method.

[0052] Furthermore, the control unit 95 compares the ambient humidity detected by the humidity sensor 91 with a preset standard humidity, and if the detected ambient humidity is higher than the standard humidity, estimates that the amount of moisture contained in the paper is greater than a predetermined amount. The standard humidity is, for example, the average humidity in the usage environment of the image forming system 1. This method is referred to as a second estimation method.

[0053] Furthermore, the control unit 95 compares the amount of ink calculated by the counting unit with a preset standard amount, and if the calculated amount is greater than the standard amount, estimates that the amount of moisture contained in the paper is greater than a predetermined amount. The standard amount is, for example, the average amount of ink used in an image formed on one sheet of paper by the image forming system 1. This method is referred to as the third estimation method.

[0054] When the control unit 95 estimates that the moisture content of the paper is greater than a predetermined moisture content in any of the first to third estimation methods, the control unit 95 alternately turns on and off the adjacent heaters 51A and 51B, but sets the on time longer than the preset standard on time. At this time, as shown in FIG. 3A, the control unit 95 alternately turns on and off the adjacent heaters 51A and 51B.

[0055] On the other hand, if any of the first to third estimation methods determines that the amount of moisture contained in the paper is not greater than the predetermined amount of moisture, the control unit 95 turns the heater 51 on and off for a fixed period of time.

[0056] By turning on the heater 51 in this manner, the air that has entered the housing 53 is heated by infrared rays radiated from the heater 51. The air heated in this manner is blown onto the paper transported along the transport surface 61a of the transport belt 61, thereby drying the ink.

[0057] As the paper is transported from the upstream side to the downstream side along the transport surface 61a, the ink is dried by the heating unit 23.

[0058] In addition, while the paper is transported on the transport surface 61a, the inside of the case 45 of the heating section 23 and the inside of the housing 53 of the heater unit 43 become a high-humidity and high-temperature environment, so the exhaust fan 49 (see FIG. 1) is driven to circulate the air.

[0059] The paper transported downstream along transport surface 61a is transported to cooling section 29, where it is cooled, and then transported through discharge port 33 to post-processing device 9 (see FIG. 1).

[0060] As is clear from the above description, according to the drying device 7 of the present invention, when the moisture content of the paper is greater than a predetermined moisture content, the heater 51 is turned on for a longer time than normal. This increases the amount of energy that the image (ink) receives, allowing images with a high moisture content to be dried appropriately and preventing yellowing and curling.

[0061] Furthermore, since the control unit 95 alternately turns on and off the adjacent heaters 51, the temperature gradient on the transport surface 61a can be reduced, and the paper transported on the transport surface 61a can be uniformly heated.

[0062] A modified example of the above embodiment will be described. As shown in Fig. 3B, a plurality of heaters 51 may be arranged in a lattice pattern aligned in the conveying direction X and the width direction Y. When the estimated moisture content is greater than a predetermined moisture content, the control unit 95 alternately turns on and off the heaters 51A and 51B adjacent to each other in the conveying direction X and the width direction Y, and makes the lighting time longer than the standard lighting time.

[0063] In this modified example as well, when the moisture content of the paper is greater than a predetermined moisture content, the heater 51 is turned on for a longer period than in the standard period, so that images with a large moisture content can be dried appropriately. Furthermore, since the heaters 51 adjacent to each other in the transport direction X and the width direction Y are alternately turned on and off, the temperature gradient on the transport surface 61a can be reduced, and the paper transported on the transport surface 61a can be heated more uniformly.

[0064] Next, another embodiment will be described.

[0065] In another embodiment, when the estimated moisture amount is greater than a predetermined moisture amount, the control unit 95 may control the heater 51 to emit infrared rays with a shorter wavelength. In this case, for example, a filter (not shown) that passes a predetermined wavelength is supported in the heating unit 23 so as to be movable between an emission position below each heater 51 and a retracted position spaced apart from below each heater 51. When the estimated moisture amount is greater than the predetermined moisture amount, the control unit 95 moves the filter from the retracted position to the emission position. This allows the wavelength of the infrared rays emitted by the heater 51 to be shifted to a shorter range.

[0066] In this case as well, when the moisture content of the paper is greater than a predetermined moisture content, the energy of the emitted infrared rays becomes high, so that images with a high moisture content can be dried appropriately.

[0067] In still another embodiment, when the estimated moisture content is greater than a predetermined moisture content, the control unit 95 may control the transport motor 69 to make the transport speed of the paper slower than the standard transport speed. In this case, the time during which the paper passes through the transport surface 61a, i.e., the time during which infrared rays are radiated to the paper, becomes longer than in the case of the standard transport speed, so the amount of energy received by the paper increases. Therefore, images with a high moisture content can be properly dried.

[0068] In still another embodiment, when the estimated moisture content is greater than a predetermined moisture content, the control unit 95 may control the lift motor 73 to move the transport surface 61a of the transport belt 61 closer to the heating unit 23. In this case, the distance between the heating unit 23 and the paper transported on the transport surface 61a becomes shorter than the standard distance, and the strength of the infrared rays radiated to the paper becomes stronger, so that images with a high moisture content can be properly dried.

[0069] In the above embodiment, the control unit 95 estimates that the amount of moisture contained in the paper is high when the ambient humidity is higher than the standard humidity (first estimation method), when the thickness of the paper is thicker than the standard thickness (second estimation method), or when the amount of ink is higher than the standard amount (third estimation method). However, since the ambient humidity has the greatest effect on the amount of moisture contained in the paper, it may be possible to estimate that the amount of moisture contained in the paper is high at least when the ambient humidity is higher than the standard humidity (first estimation method). Alternatively, the first estimation method may be combined with the second estimation method or the third estimation method.

[0070] Furthermore, when it is estimated that the moisture content of the paper is greater than a predetermined moisture content, the control unit 95 may control both the heating unit 23 and the conveying unit 25 so as to increase the amount of energy that the image receives. For example, the turn-on time of the heater of the heating unit 23 may be made longer than the standard time, and the conveying speed of the conveying belt 61 may be made slower than the standard time.

[0071] In the above embodiment, the amount of moisture contained in the paper is estimated by comparing the ambient humidity, the thickness of the paper, and the amount of ink with standard values, and if the estimated amount of moisture is greater than a predetermined amount of moisture, the amount of energy received by the image is increased. However, the standard values ​​for comparison may be set to two or more levels, and the amount of energy received by the image may be increased by two or more levels. Also, the amount of energy received by the ink may be adjusted based on the absolute values ​​of the ambient humidity, the thickness of the paper, and the amount of ink.

[0072] Although the present invention has been described with respect to a specific embodiment, the present invention is not limited to the above embodiment. Various changes, substitutions, and modifications may be made without departing from the scope and spirit of the present invention, and the claims include all embodiments that may be included within the scope of the technical concept. [Explanation of symbols]

[0073] 1. Image forming system 5. Image forming device 7 Drying equipment 11 Ultrasonic sensor (measurement part) 23 Heating section 25 Conveyor 51 Heater 91 Humidity sensor (measurement part) 95 Control section (measurement section)

Claims

1. A drying device that dries a medium on which an image is formed with ink while conveying the medium, comprising: a transport unit that transports the medium in a predetermined transport direction; a heating section that supplies energy to the image to dry the image; A measurement unit that measures a value related to the amount of moisture contained in the medium; a control unit that estimates a moisture content of the medium based on the value measured by the measurement unit, and controls at least one of the transport unit and the heating unit so as to change the amount of energy received by the image in accordance with the estimated moisture content; A drying device characterized in that the measurement unit is a sensor that detects the thickness of the medium, and the control unit estimates that the amount of moisture contained in the medium is greater than a predetermined moisture amount when the thickness detected by the sensor is greater than a standard thickness.

2. The drying device according to claim 1, characterized in that the control unit controls at least one of the transport unit and the heating unit so as to increase the amount of energy received by the image when the estimated moisture amount is greater than the predetermined moisture amount.

3. The heating unit includes a plurality of heaters that can be turned on and off individually and are turned on and off at a predetermined frequency; 3. The drying device according to claim 2, wherein the control unit extends a turn-on time of the heaters longer than a standard turn-on time when the estimated moisture content is greater than the predetermined moisture content.

4. The plurality of heaters are arranged side by side in the transport direction, The drying device according to claim 3 , wherein the control unit alternately turns on and off the heaters adjacent to each other.

5. the plurality of heaters are arranged in a lattice pattern in the transport direction and in a width direction intersecting the transport direction, The drying device according to claim 3 , wherein the control unit alternately turns on and off the heaters adjacent to each other in the transport direction and the width direction.

6. The heating unit includes a heater that emits light, The drying device according to claim 2, characterized in that the control unit controls the heating unit to make the wavelength of the light shorter than the standard wavelength when the estimated moisture content is greater than the predetermined moisture content.

7. The drying device according to claim 2, characterized in that the control unit controls the transport unit to make the transport speed of the medium slower than the standard transport speed when the estimated moisture content is greater than the predetermined moisture content.

8. the conveying unit or the heating unit is provided movably so as to change the interval between the conveying unit and the heating unit; The drying device according to claim 2, characterized in that, when the estimated moisture content is greater than the predetermined moisture content, the control unit moves the conveying unit or the heating unit so as to shorten the interval between the conveying unit and the heating unit compared to the standard interval.

9. an image forming device for forming an image on a medium; 9. An image forming system comprising: the drying device according to claim 1, which dries a medium on which an image has been formed by the image forming apparatus while conveying the medium.

Images