Sheet drying apparatus and image forming system equipped therewith

Abstract

This invention provides a sheet drying apparatus and an image forming system equipped therewith, which can set appropriate drying performance according to the characteristics of the sheet to be dried, environmental conditions, and printing conditions. [Solution] The sheet drying apparatus comprises a conveying unit, a drying unit, a heater voltage power supply, a heating unit moving mechanism, a drying unit temperature and humidity sensor, and a control unit. The drying unit has a heating unit equipped with a heater positioned opposite the conveying unit, and heats and dries the sheet by positioning the heater at a heating position a predetermined distance away from the conveying unit. The heating unit moving mechanism moves the heating unit back and forth in a direction toward the conveying unit and in a direction toward the conveying unit. The drying unit temperature and humidity sensor detects the temperature and humidity inside the drying unit. The control unit changes the heating position from the initial position by raising and lowering the heating unit based on output information regarding the sheet characteristics, the elapsed time since the start of power supply to the heater, and the temperature and humidity inside the drying unit.

Description

Technical Field

[0001] The present invention relates to a sheet drying device for drying a sheet on which an image is printed by an inkjet recording device or the like, and an image forming system including the same.

Background Art

[0002] Conventionally, as a recording device such as a facsimile machine, a copying machine, or a printer, an inkjet recording device that discharges ink onto a sheet to form an image has been widely used. Further, a sheet drying device that heats and dries a sheet (paper) to which ink has been attached by an inkjet recording device is known.

[0003] In a sheet drying device, the drying performance required to sufficiently dry a wide variety of sheets varies depending on the amount of ink per unit area attached to the sheet. That is, the higher the amount of ink per unit area, the more necessary it is to enhance the drying performance. If the drying of the sheet is insufficient, the ink may adhere to the rollers that convey the sheet and may then adhere to the next sheet to be conveyed. On the other hand, if the drying conditions of the sheet are too strong, there is a risk of blistering when drying using a heater, or an unintended gloss may occur on the printed matter.

[0004] As a method of controlling the drying ability according to the amount of ink per unit area, Patent Document 1 discloses an inkjet recording device that sets the rotation speed of a blower fan for drying a recording medium in a plurality of stages according to the average printing rate of a recorded image. Patent Document 2 discloses an adhesive coating device including a drying means for drying an end portion of a sheet on which an image is transferred by an inkjet recording method, and an adhesive coating means for applying an adhesive to the end portion of the sheet dried by the drying means, and adjusting the distance between the drying means and the end portion of the sheet according to the number of sheets, the sheet size, and the basis weight of the sheet.

Prior Art Documents

Patent Documents

[0006] Patent documents 1 and 2 describe inventions relating to the drying of roll-shaped recording media. However, when the recording media is cut paper, it is assumed that the size and type of paper will vary considerably from one printing job to the next. Furthermore, appropriate drying conditions vary not only depending on the size and type of recording media, but also on environmental conditions (temperature and humidity) and printing conditions (print density). Therefore, it was necessary to adjust the drying conditions in accordance with changes in environmental and printing conditions during printing.

[0007] In view of the above problems, the present invention aims to provide a sheet drying apparatus and an image forming system equipped therewith that can set appropriate drying performance according to the characteristics of the sheet to be dried, environmental conditions, and printing conditions. [Means for solving the problem]

[0008] To achieve the above objective, the first configuration of the present invention is a sheet drying apparatus comprising a transport unit, a drying unit, a heater voltage power supply, a heating unit moving mechanism, a drying unit temperature and humidity sensor, and a control unit. The transport unit transports a sheet on which an image has been formed with ink containing moisture. The drying unit has a heating unit equipped with a heater positioned opposite the transport unit, and heats and dries the sheet by positioning the heater at a heating position a predetermined distance away from the transport unit. The heater voltage power supply energizes the heater. The heating unit moving mechanism moves the heating unit back and forth in a direction toward the transport unit and in a direction toward the transport unit. The drying unit temperature and humidity sensor detects the temperature and humidity inside the drying unit. The control unit controls the heater voltage power supply and the heating unit moving mechanism. The control unit can change the heating position from the initial position by raising and lowering the heating unit based on output information regarding the characteristics of the sheet, the elapsed time since the start of energization to the heater, and the temperature and humidity inside the drying unit. [Effects of the Invention]

[0009] According to the first configuration of the present invention, the heating position of the heater can be changed from its initial position according to the characteristics of the sheet, the elapsed time since the start of power supply to the heater, and the temperature and humidity inside the drying section, thereby adjusting to drying conditions that are necessary and sufficient for drying the sheet. Therefore, the sheet can be dried stably without being affected by the type of sheet, printing density, environmental conditions, etc., and blistering due to excessive heating of the sheet and the occurrence of unintended gloss can also be suppressed. [Brief explanation of the drawing]

[0010] [Figure 1] A schematic diagram showing the internal configuration of an image forming system 200 equipped with the sheet drying apparatus 10 of the present invention. [Figure 2] Side cross-sectional view of the area around the drying section 40 of a sheet drying apparatus 10 according to one embodiment of the present invention. [Figure 3] Enlarged view of the drying section 40 in Figure 2 [Figure 4] Block diagram showing an example of the control path for the sheet drying device 10. [Figure 5]A flowchart showing an example of control for adjusting the heating position of the heater 43 in the sheet drying apparatus 10 of this embodiment. [Modes for carrying out the invention]

[0011] [1. Configuration of the image forming system including the sheet drying device] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a schematic diagram showing the internal configuration of an image forming system 200 equipped with the sheet drying apparatus 10 of the present invention. Figure 2 is a side cross-sectional view of the area around the drying section 40 of the sheet drying apparatus 10 according to one embodiment of the present invention. An image forming system 200, which consists of an image forming apparatus 100 and a sheet drying apparatus 10, will be described with reference to Figures 1 and 2.

[0012] The image forming apparatus 100 is an inkjet recording type printer and comprises a paper feed unit 2 located at the bottom of the image forming apparatus 100, an image forming unit 3 located above the paper feed unit 2, and a paper feeding unit 4 that feeds the paper P (sheet) contained in the paper feed unit 2 to the image forming unit 3.

[0013] The image forming unit 3 consists of a recording unit 3a having multiple recording heads and a print transport unit 3b positioned opposite the recording unit 3a. The print transport unit 3b is equipped with an endless print transport belt 5 wrapped around multiple rollers, including a drive roller. Paper P transported by the paper feeding unit 4 passes below the recording unit 3a while being held in place by a paper suction unit (not shown) located inside the print transport belt 5. Paper P on which a predetermined image has been recorded by the image forming unit 3 is discharged from the discharge roller pair 6 and transported to the sheet drying device 10.

[0014] The image forming apparatus 100 includes an operation panel 101 and a main body control unit 102. The operation panel 101 is an operation unit for receiving various setting inputs. For example, the user can operate the operation panel 101 to input the size information of the paper P. Also, by operating the operation panel 101, the number of sheets of paper P to be printed can be input, and the start of a print job can be instructed. The main body control unit 102 controls the overall operation of the image forming apparatus 100 and controls each part of the image forming apparatus 100.

[0015] The sheet drying device 10 is arranged adjacent to the image forming apparatus 100 and dries the ink on the paper P discharged from the image forming apparatus 100. The sheet drying device 10 includes a first conveyance unit 20, a preliminary drying unit 30, a drying unit 40, a suction fan unit 50, and a second conveyance unit 70.

[0016] The first conveyance unit 20 includes a driving roller 21a, a driven roller 21b, and a conveyance belt 22. The conveyance belt 22 is wound around a driving roller 21a arranged on the downstream side with respect to the conveyance direction of the paper P (from right to left in FIG. 1, hereinafter simply referred to as the conveyance direction) and a driven roller 21b arranged on the upstream side.

[0017] Paper suction portions 23a and 23b are arranged inside the conveyance belt 22. The conveyance belt 22 is formed with a number of suction holes (not shown) through which a suction wind for sucking the paper P onto the conveyance belt 22 by negative pressure suction by the paper suction portions 23a and 23b passes.

[0018] Belt cooling fans 24 are arranged at two locations below the conveyance belt 22. Also, a belt temperature sensor 25 is arranged in contact with and separated from the lower surface of the conveyance belt 22. The belt cooling fan(s) 24 blow cooling air to the conveyance belt when the detected temperature of the belt temperature sensor 25 becomes a predetermined temperature or higher.

[0019] The preliminary drying unit 30 is arranged closest to the downstream side of the sheet inlet 61 with respect to the conveyance direction, and preliminarily dries the ink on the paper P carried in from the sheet inlet 61. The preliminary drying unit 30 includes a paper blowing fan 31 and a paper blowing duct 32 for blowing air onto the paper P from above.

[0020] The drying unit 40 is arranged adjacent to the downstream side of the preliminary drying unit 30 with respect to the conveyance direction, and dries the ink on the paper P that has passed through the preliminary drying unit 30. The drying unit 40 includes two heating units 41 arranged so as to face the upper surface of the conveyance belt 22.

[0021] The suction fan unit 50 sucks the water vapor generated from the paper P passing through the drying unit 40. The suction fan unit 50 includes a suction fan 51 that sucks the air containing water vapor in the drying unit 40, and a separation fan 52 that blows separation air for separating the paper P from the conveyance belt 22. The suction fan unit 50 communicates with the space between the conveyance belt 22 and the heating unit 41 via the first duct 53, and communicates with the exhaust port 60 formed in the upper part of the sheet drying device 10 via the second duct 54.

[0022] Also, a plurality of outside air introduction fans 63 for taking in outside air are arranged at appropriate positions inside the sheet drying device 10. Sheet detection sensors 64 and 65 are arranged at the upstream part and the downstream part of the first conveyance unit 20, respectively. The sheet detection sensors 64 and 65 detect that the paper P has passed through the sheet inlet 61 and the sheet outlet 62.

[0023] By the rotational drive of the drive roller 21a causing the conveyance belt 22 to rotate counterclockwise, the paper P carried in from the sheet inlet 61 sequentially passes through the preliminary drying unit 30 and the drying unit 40, and is discharged from the sheet outlet 62 to the outside of the sheet drying device 10, or is carried into the second conveyance unit 70.

[0024] The second transport unit 70 is positioned below the drying unit 40 and the pre-drying unit 30, with the first transport unit 20 in between. The second transport unit 70 includes an inversion transport path 70a for inverting the front and back sides of the paper P after the ink has dried, and a double-sided transport path 70b for returning the paper P, with its front and back sides inverted, back to the image forming apparatus 100 when double-sided printing is performed on the paper P.

[0025] An arc-shaped retraction path 71 is provided downstream of the suction fan unit 50 (left side in Figure 1) in the transport direction. The retraction path 71 is used to retract and store paper P (waste paper) that has become unnecessary due to printing defects or other issues in the image forming apparatus 100.

[0026] [2. Configuration of the sheet drying apparatus] Figure 3 is an enlarged view of the drying section 40 in Figure 2. The drying section 40 comprises a heating unit 41 and a hot air fan 42 (see Figure 2). Two sets of heating units 41 are arranged along the conveying direction (arrow X direction). Each heating unit 41 comprises a heater 43 and a reflector 44. The heating unit 41 can be moved by a heating unit moving mechanism 45 (see Figure 4) between a heating position facing the conveyor belt 22 (position in Figure 3) and a separated position away from the conveyor belt 22 (not shown).

[0027] The heater 43 is rod-shaped and extends in the sheet width direction (the direction perpendicular to the plane of the paper in Figure 3; hereinafter simply referred to as the width direction), which is horizontal and perpendicular to the conveying direction. Multiple heaters 43 (12 in this embodiment) are arranged in parallel along the conveying direction in the heating unit 41. In this embodiment, infrared heaters are used as the heaters 43.

[0028] The reflector 44 is a U-shaped reflector in side view, positioned to surround each heater 43 from above. The infrared rays emitted from the heater 43 are reflected downward by the inner surface of the reflector 44 and irradiated onto the paper P being carried on the conveyor belt 22. As a result, the moisture in the ink on the paper P evaporates and dries, and the ink is fixed onto the paper P.

[0029] The hot air fan 42 is positioned above the heating unit 41. More specifically, the hot air fan 42 is positioned to blow air from above toward the reflector 44. The air blown by the hot air fan 42 toward the reflector 44 is heated as it passes through the gaps between each reflector 44, becoming warm air, which then flows into the gap (drying space) between the heating unit 41 and the conveyor belt 22.

[0030] If steam or water vapor is present in the gap between the heating unit 41 and the conveyor belt 22, the infrared rays emitted from the heater 43 and reflected by the reflector 44 will be absorbed by the steam or water vapor, hindering the drying ability of the ink on the paper P. Therefore, by blowing hot air into the gap between the heating unit 41 and the conveyor belt 22 using the hot air fan 42, the steam or water vapor generated from the paper P is dispersed and removed, thereby maintaining the drying ability of the ink by infrared rays.

[0031] A first duct 53 is provided between the drying unit 40 and the suction fan unit 50 for sucking in steam and water vapor generated from the paper P along with air. The first duct 53 extends from the gap between the heating unit 41 and the conveyor belt 22 to the suction fan 51 inside the suction fan unit 50.

[0032] Two temperature sensors 75 are positioned in the drying section 40, opposite the two heating units 41. The temperature and humidity sensors 75 detect the temperature and humidity inside the drying section 40. The detection results are transmitted to the control unit 90 (see Figure 4).

[0033] Figure 4 is a block diagram showing an example of the control path of the sheet drying apparatus 10 in this embodiment. Here, we will focus on explaining the portion of the control path of the sheet drying apparatus 10 that is necessary for implementing the present invention.

[0034] The control unit 90 includes a CPU (Central Processing Unit) 91 as a central processing unit, a ROM (Read Only Memory) 92 as a read-only memory, a RAM (Random Access Memory) 93 as a read-write memory, a temporary memory unit 94 for temporarily storing data necessary for controlling each part of the sheet drying apparatus 10, and at least a plurality (two in this case) of I / F (interfaces) 96 for transmitting control signals to each device in the sheet drying apparatus 10 and receiving input signals from the operation unit 80.

[0035] ROM 92 stores data that should not be changed during use of the sheet drying device 10, such as the control program for the sheet drying device 10 and necessary control values. RAM 93 stores necessary data generated during the control of the sheet drying device 10, as well as data temporarily required for the control of the sheet drying device 10. RAM 93 (or ROM 92) also stores data used to control the heating position of the heater 43, such as the size and type of paper P, the print density of the image formed on the paper P, the elapsed time since the heater 43 was turned on, and the relationship between the temperature and humidity in the drying chamber 40 and the heating position of the heater 43 (parameter values ​​listed in Tables 1 to 7 below). Counter 95 counts the number of sheets of paper P that are brought in by accumulating them.

[0036] Furthermore, the control unit 90 transmits control signals from the CPU 91 to each part and device in the sheet drying apparatus 10 via the I / F 96. In addition, signals indicating their status and input signals are transmitted from each part and device to the CPU 91 via the I / F 96. Examples of parts and devices controlled by the control unit 90 include the first transport unit 20, the pre-drying unit 30, the drying unit 40, the heating unit moving mechanism 45, the suction fan unit 50, the second transport unit 70, the sheet detection sensors 64a and 64b, the operation unit 80, the drying unit temperature and humidity sensor 75, and the voltage control circuit 84.

[0037] The heating unit moving mechanism 45 moves the heating unit 41 to a heating position facing the conveyor belt 22 (position shown in Figure 3) and to a separated position away from the conveyor belt 22 (not shown) based on a control signal from the control unit 90. The heating unit moving mechanism 45 also adjusts the heating position of the heating unit 41 based on a control signal from the control unit 90. The heating unit moving mechanism 45 can use conventionally known moving mechanisms, such as a combination of a motor and a rack and pinion mechanism, or a combination of a motor and a wire winding / unwinding mechanism.

[0038] The voltage control circuit 84 is connected to the fan drive voltage power supply 85 and the heater voltage power supply 86, and operates these power supplies by output signals from the control unit 90. Each of these power supplies, in response to a control signal from the voltage control circuit 84, applies a predetermined voltage to the belt cooling fan 24 of the transport unit 20 and the hot air fan 42 in the heating unit 41 via the fan drive voltage power supply 85, and to the heater 43 in the heating unit 41 via the heater voltage power supply 86.

[0039] The control unit 80 is equipped with a liquid crystal display 81 and LEDs 82 that indicate various statuses. The user can stop drying the paper P by operating the stop / clear button on the control unit 80, and reset the various settings of the sheet drying device 10 to their default state by operating the reset button. The liquid crystal display 81 is designed to show the status of the sheet drying device 10, as well as the drying status of the paper P and the number of sheets of paper P that have been loaded. The various settings of the sheet drying device 10 may also be made from the control panel 101 of the image forming apparatus 100 or from a personal computer.

[0040] The external temperature and humidity sensor 83 detects the temperature and humidity outside the sheet drying device 10. The detection results are transmitted to the control unit 90. The external temperature and humidity sensor 83 is positioned in a location within the sheet drying device 10 that is less affected by the heat of the pre-drying section 30 and the drying section 40.

[0041] [3. Adjusting the heating position of the heater] The drying performance (infrared irradiation intensity) of the heater 43 required for drying the paper P varies depending on the type, size, and thickness of the paper P. It also varies depending on the amount of ink used for image recording in the image forming apparatus 100. Therefore, simply adjusting the infrared irradiation intensity by turning the heater 43 on and off may not be sufficient to ensure stable drying of the paper P.

[0042] Furthermore, the temperature inside the drying unit 40 differs between immediately after printing starts and after printing has been continued for a long period of time. More specifically, immediately after printing starts, the temperature inside the drying unit 40 is low because it has not yet warmed up completely. Then, when printing is continued for a predetermined time, the temperature inside the drying unit 40 saturates to a certain temperature. In addition, when continuously printing images with a high print density, the humidity inside the drying unit 40 increases due to the vapor generated when the ink evaporates, creating conditions that make drying difficult.

[0043] Therefore, in this embodiment, the heating position of the heater 43 (distance between the conveyor belt 22 and the heater 43) is adjusted based on output information regarding the characteristics of the paper P and environmental conditions. Specifically, information regarding the characteristics of the paper P (type, size, thickness, and print density of the paper P) is input from the image forming apparatus 100. In addition, the temperature and humidity inside the drying section 40 are input based on the detection result of the drying section temperature and humidity sensor 75. The control unit 90 changes the heating position of the heater 43 from the default (initial position) to a predetermined adjustment position according to the input output information regarding the characteristics of the paper P and the temperature and humidity inside the drying section 40.

[0044] Specifically, when the size of the paper P is large, when the paper P is thick, when the print density of the image printed on the paper P is high, when the temperature inside the drying section 40 is low, when the humidity inside the drying section 40 is high, or under other conditions where the paper P is difficult to dry, the distance between the paper P (conveyor belt 22) and the heater 43 is reduced. In other words, the heating position of the heater 43 is lowered.

[0045] On the other hand, when the size of the paper P is small, when the paper P is thin, when the print density of the image printed on the paper P is low, when the temperature inside the drying section 40 is high, when the humidity inside the drying section 40 is low, or under other conditions where the paper P is prone to drying, the distance between the paper P (conveyor belt 22) and the heater 43 is increased. In other words, the heating position of the heater 43 is raised.

[0046] As described above, there are multiple pieces of information for adjusting the heating position of the heater 43. In this embodiment, in order to simplify the procedure for determining the appropriate heating position, a parameter value is stored in advance for each piece of information used to determine the heating position of the heater 43, which moves the heating position of the heater 43 from its initial position (default position). Then, the heating position of the heater 43 is moved from its initial position by the sum of the parameter values ​​of each piece of information.

[0047] Tables 1 to 7 show examples of parameter value settings. If the parameter value in Tables 1 to 7 is positive, the heating position is lowered from the initial position (the heater 43 is brought closer to the paper P). If the parameter value is negative, the heating position is raised from the initial position (the heater 43 is moved further away from the paper P). If the parameter value is 0, the heating position is maintained at the initial position.

[0048] [Table 1]

[0049] Table 1 shows examples of parameter value settings for the elapsed time since the heater 43 was turned on. Before a predetermined time has elapsed since the heater 43 was turned on, the drying section 40 is not sufficiently heated, making it difficult to dry the paper P. Therefore, the parameter value is set to +1 to lower the heating position below the initial position. After a predetermined time has elapsed since the heater 43 was turned on, the drying section 40 is sufficiently heated, so the parameter value is set to 0 to return the heating position to the initial position.

[0050] [Table 2]

[0051] Table 2 shows examples of parameter values ​​for the print density of the image printed on paper P. As the print density increases, the amount of ink ejected onto paper P increases, making it more difficult for paper P to dry. Therefore, as the print density increases, the parameter value should be increased to the positive side to lower the heating position from the initial position. Conversely, as the print density decreases, the parameter value should be increased to the negative side to raise the heating position from the initial position.

[0052] [Table 3]

[0053] Table 3 shows examples of parameter value settings for different paper sizes P. As the size of paper P increases, it becomes more difficult for the paper P to heat up and dry. Therefore, when paper P is large, the parameter value is set to +2 to lower the heating position from the initial position. Also, when paper P is large, the parameter value is set to -2 to raise the heating position from the initial position.

[0054] [Table 4]

[0055] Table 4 shows examples of parameter values ​​for different paper thicknesses. As the paper thickness increases, it becomes more difficult to heat up and dry. Therefore, when the paper is thick, the parameter value is set to +2 to lower the heating position from the initial position. When the paper is thin, the parameter value is set to -2 to raise the heating position from the initial position.

[0056] [Table 5]

[0057] Table 5 shows examples of parameter value settings for different types of paper P. If the surface of paper P is coated, the ink will not evaporate easily, and the paper P will not dry easily. Therefore, when paper P is coated paper, the parameter value is set to +2, and the heating position is lowered from the initial position. Also, when paper P is inkjet matte paper, which has a high ink evaporation rate, the parameter value is set to -2, and the heating position is raised from the initial position.

[0058] [Table 6]

[0059] Table 6 shows examples of parameter values ​​for the temperature inside the drying section 40. When the temperature inside the drying section 40 is low, the paper P is difficult to dry, so the parameter value is set to +2 and the heating position is lowered from the initial position. Conversely, when the temperature inside the drying section 40 is high, the paper P dries easily, so the parameter value is set to -2 and the heating position is raised from the initial position.

[0060] [Table 7]

[0061] Table 7 shows examples of parameter values ​​for humidity inside the drying section 40. When the humidity inside the drying section 40 is high, the paper P is difficult to dry, so the parameter value is set to +2 and the heating position is lowered from the initial position. Conversely, when the humidity inside the drying section 40 is low, the paper P dries easily, so the parameter value is set to -2 and the heating position is raised from the initial position.

[0062] Then, the parameter values ​​determined based on Tables 1 to 7 are added together to calculate the final parameter value (adjustment parameter value) for adjusting the heating position. In addition, the amount of movement (travel distance) A of the heater 43 when the parameter value changes by ±1 is set in advance, and the amount of movement from the initial position of the heating position is determined by multiplying the amount of movement A by the adjustment parameter value.

[0063] For example, if a predetermined time has not elapsed since the heater 43 was turned on (+2), the image to be printed has a low print density (-2), the paper P is thin paper (-2), the type of paper P is plain paper (0), the size of paper P is standard size (0), the temperature inside the drying section 40 is low (+2), and the humidity is normal (0), then the parameter value obtained by adding up each parameter (2 + (-2) + (-2) + 0 + 0 + 1 + 0) is (-1), which becomes the adjustment parameter value. If the amount of movement A is 1 [cm], then (-1) × 1 [cm] = -1 cm, and the position where the heater 43 is moved 1 cm away from the paper P from its initial position is taken as the heating position.

[0064] Furthermore, if a predetermined time has elapsed since the heater 43 was turned on (0), the image to be printed has an ultra-high print density (+4), the paper P is plain paper (0), the type of paper P is coated paper (+2), the size of paper P is large (+2), the temperature inside the drying section 40 is normal (0), and the humidity is normal (0), then the parameter value obtained by adding up each parameter (0+4+0+2+2+0+0) (+8) becomes the adjustment parameter value. If the amount of movement A is 1 [cm], then (+8) × 1 [cm] = +8cm, and the position where the heater 43 is moved 8cm closer to the paper P from its initial position is defined as the heating position.

[0065] The heater 43 has upper and lower heating limits. For example, the upper limit is set at -10cm from the initial position (0), and the lower limit is set at +10cm from the initial position (0). In this case, if the adjustment parameter value exceeds +10, the heating position of the heater 43 is set to the upper limit. Also, if the adjustment parameter value exceeds -10, the heating position of the heater 43 is set to the lower limit.

[0066] In this way, based on the output information regarding the characteristics of the paper P transmitted from the image forming apparatus 100 (type, size, thickness, and print density of the paper P), the control unit 90 automatically adjusts the heater 43 to the optimal heating position. This eliminates the need for the user to perform test printing and test drying to adjust the heating position, thus reducing working time.

[0067] Furthermore, the heating position of the heater 43 may be adjusted manually, not just automatically. In the case of manual adjustment, the user adjusts to the desired heating position by selecting a menu setting value using the operating unit 80 of the sheet drying device 10. With manual adjustment, the user can adjust to the desired heating position for various types of paper, ink, and printing density (ink load), allowing for flexible adaptation to the diversity of paper and ink.

[0068] Furthermore, if the heating position is manually adjusted, it is preferable to automatically return the heater 43 to its initial position after the job is completed. This eliminates the risk that the next job (drying process) will be executed with the heating position used in the previous job.

[0069] Furthermore, when adjusting the heating position of the heater 43, the airflow of the hot air fan 42 and the belt cooling fan 24 can also be changed in conjunction with the change in heating position, allowing the paper P to be dried more efficiently and reducing power consumption.

[0070] Figure 5 is a flowchart illustrating an example of control for adjusting the heating position of the heater 43 in the sheet drying apparatus 10 of this embodiment. The control procedure for automatically adjusting the heating position of the heater 43 will be explained according to the steps in Figure 5, referring to Figures 1 to 4 as needed. In the initial state, the heating position of the heater 43 is assumed to be set to the initial position (default position). In the following explanation, output information regarding the characteristics of the paper P will also be simply referred to as the output information of the paper P.

[0071] When a print command to the paper P is input from the main control unit 102 of the image forming apparatus 100, the output information of the paper P is input to the control unit 90 of the sheet drying apparatus 10 along with a command to start drying the paper P (step S1). Of the output information of the paper P, information regarding the physical properties of the paper P, such as the size, thickness, and type of the paper P, is input from the operation panel 101 of the image forming apparatus 100 (see Figure 1). For example, the manufacturer, product name, and product number of the paper P may be stored in the main control unit 102 in advance, associated with the corresponding information regarding the physical properties of the paper P. This allows the main control unit 102 to recognize the information regarding the physical properties of the paper P to be used simply by the user selecting the manufacturer, product name, and product number of the paper P from the operation panel 101.

[0072] Information regarding the print density of paper P is calculated by the main unit control unit 102 based on image data transmitted from a higher-level device such as a personal computer, and input to the control unit 90.

[0073] The control unit 90 determines whether or not adjustment of the heating position of the heater 43 is necessary based on the output information of the input paper P (step S2). Specifically, the control unit 90 obtains parameter values ​​(Tables 1 to 7) based on the output information of the paper P, the elapsed time since the heater 43 was turned on, and the temperature and humidity inside the drying unit 40, and calculates an adjustment parameter value by adding each parameter value. The control unit 90 determines that no adjustment of the heating position is necessary if the adjustment parameter value is 0, and determines that adjustment of the heating position is necessary if the adjustment parameter value is other than 0.

[0074] If it is determined that adjustment of the heating position is necessary (Yes in step S2), the control unit 90 sends a control signal to the heating unit moving mechanism 45 to raise or lower the heating unit 41, moving the heating position of the heater 43 from the initial position to the adjustment position (step S3). If it is determined that adjustment of the heating position is not necessary (No in step S2), the heating position of the heater 43 is set to the initial position and the process proceeds to the next step.

[0075] Next, the image forming apparatus 100 starts printing on the paper P, and the sheet drying apparatus 100 starts drying the paper P (step S4). Based on the detection signal from the sheet detection sensor 64, the control unit 90 counts the number of sheets of paper P being fed into the sheet drying apparatus 10 using the counter 95 (step S5).

[0076] Next, the control unit 90 determines whether there have been any changes in the output information of the paper P, the elapsed time since the heater 43 was turned on, or the parameter values ​​(Tables 1 to 7) based on the temperature and humidity inside the drying unit 40 (step S6). For example, if a predetermined time has elapsed since the heater 43 was turned on, the parameter value (Table 1) based on the elapsed time since the heater 43 was turned on is changed from +1 to 0. Also, if the print density is changed from normal to high print density, the parameter value (Table 2) based on the print density is changed from 0 to +2.

[0077] Furthermore, if the temperature inside the drying section 40 changes from normal to high temperature, the parameter value based on the temperature inside the drying section 40 (Table 6) changes from 0 to -1. Alternatively, if the humidity inside the drying section 40 changes from normal to high humidity, the parameter value based on the humidity inside the drying section 40 (Table 7) changes from 0 to +1.

[0078] If there is a change in the parameter value (Yes in step S6), the control unit 90 raises or lowers the heating unit 41 by the amount of the change in the parameter value to readjust the heating position of the heater 43 (step S7) and continues the drying process of the paper P. If there is no change in the parameter value (No in step S6), the drying process of the paper P continues without readjusting the heating position.

[0079] The control unit 90 determines whether a predetermined number of sheets of paper P have been loaded and the drying process has been completed (step S8). If the drying process is still ongoing (No in step S8), the unit returns to step S5 and continues counting the number of loaded sheets. If the drying process is complete (Yes in step S8), the unit turns off the heater 43 and terminates the process.

[0080] According to the control example shown in Figure 5, the heating position of the heater 43 is automatically adjusted based on the output information of the paper P, the elapsed time since the heater 43 was turned on, and the temperature and humidity inside the drying section 40. As a result, the paper P can be dried stably without being affected by the type, size, thickness, and print density of the paper P, the elapsed time since the heater 43 was turned on, the temperature and humidity inside the drying section 40, etc., and unnecessary power consumption can also be reduced.

[0081] In the control example shown in Figure 5, only the heating position of the heater 43 is adjusted, but the airflow of at least one of the hot air fan 42 or the belt cooling fan 24 may also be adjusted in conjunction with the adjustment of the heating position.

[0082] Furthermore, in the control example shown in Figure 5, the duty cycle of the AC voltage applied to the heater 43 is adjusted based on the output information of the paper P, the elapsed time since the heater 43 was turned on, and the temperature and humidity inside the drying section 40. However, the duty cycle may also be adjusted based on the temperature and humidity environment outside the sheet drying device 10 detected by the external temperature and humidity sensor 83.

[0083] For example, if the external temperature and humidity sensor 83 detects that the external environment is high temperature and low humidity, the paper P will dry out easily, so the control unit 90 should change the heating position of the heater 43 to move away from the paper P. If the external environment is low temperature and high humidity, the paper P will not dry out easily, so the control unit 90 should change the heating position of the heater 43 to move closer to the paper P.

[0084] Furthermore, the present invention is not limited to the embodiments described above, and various modifications are possible without departing from the spirit of the invention. For example, in the embodiments described above, a configuration is shown in which a sheet drying device 10 is connected to an inkjet printer, which is an image forming apparatus, as an example of an image forming system. However, it is of course possible to use the sheet drying device 10 independently without connecting it to the image forming apparatus 100. [Industrial applicability]

[0085] The present invention can be used in a sheet drying apparatus for drying sheets on which images have been printed using an inkjet recording device or the like. By utilizing the present invention, it is possible to provide a sheet drying apparatus and an image forming system equipped therewith that can set appropriate drying performance according to the characteristics of the sheet to be dried, environmental conditions, and printing conditions. [Explanation of Symbols]

[0086] 10 Sheet drying device 20. First Conveyor Unit (Conveyor Unit) 22 Conveyor belt 24-belt cooling fan 30 Pre-drying section 40 Drying section 41 Heating Unit 42 Hot air fan 43 Heater 44 Reflector 45 Heating unit transfer mechanism 50 Suction Fan Units 61 Sheet loading entrance 62 Sheet Discharge Ports 64, 65 Seat detection sensors 70 Second Conveyor Unit 75 Dry section temperature and humidity sensor 80. Operation Unit (Input Unit) 83 External temperature and humidity sensor 85 Fan drive voltage power supply 86 Heater voltage power supply 90 Control Unit 100 Image forming apparatus 200 Image Forming Systems P Paper (sheet)

Claims

1. A transport unit that transports sheets on which images have been formed using water-containing ink, A drying unit having a heating unit equipped with a heater positioned opposite the conveying unit, the heater being positioned at a heating position a predetermined distance away from the conveying unit to heat and dry the sheet, A heater voltage power supply that energizes the aforementioned heater, A heating unit moving mechanism that reciprocates the heating unit in a direction toward the conveying section and in a direction toward away from the conveying section, A drying section temperature and humidity sensor for detecting the temperature and humidity inside the drying section, A control unit that controls the heater voltage power supply and the heating unit movement mechanism, In a sheet drying apparatus equipped with, The sheet drying apparatus is characterized in that the control unit can change the heating position from its initial position by raising and lowering the heating unit based on at least one of output information relating to the characteristics of the sheet, the elapsed time since the start of power supply to the heater, and the temperature and humidity inside the drying section.

2. The sheet drying apparatus according to claim 1, characterized in that the output information regarding the characteristics of the sheet includes at least one of the type, size, thickness, and print density of the sheet.

3. Based on the type, size, thickness, and printing density of the sheet, the elapsed time since the start of power supply to the heater, and the temperature and humidity inside the drying section, a plurality of parameter values ​​are set to determine the amount and direction of movement of the heating unit when moving the heating position from the initial position. The sheet drying apparatus according to claim 2, characterized in that the control unit moves the heating unit using an adjustment parameter value calculated by adding up a plurality of parameter values ​​to determine the heating position.

4. The sheet drying apparatus according to claim 3, characterized in that when at least one of the plurality of parameter values ​​is changed during the drying process of the sheet, the control unit moves the heating unit by the amount of the change in the parameter value to readjust the heating position.

5. The sheet drying apparatus is equipped with a temperature and humidity sensor that detects the temperature and humidity outside or inside the apparatus. The sheet drying apparatus according to claim 1, characterized in that the control unit can change the heating position based on the temperature and humidity detected by the temperature and humidity detection sensor.

6. It includes an input unit for selecting and inputting one of the multiple heating positions, The sheet drying apparatus according to claim 1, characterized in that when one of the plurality of heating positions is selected by the input unit, the control unit moves the heater from the initial position to the selected heating position using the heating unit moving mechanism.

7. The sheet drying apparatus according to claim 6, characterized in that the control unit selects one of a plurality of heating positions by the input unit, places the heater at the selected heating position, and when the sheet drying process is performed, returns the heater from the heating position to the initial position after the drying process is performed.

8. The drying section is Multiple heaters, which are infrared heaters, Multiple reflectors surround the heater from the direction opposite to the transport section, A heating unit having, A hot air fan is positioned on the opposite side of the conveying section, with the heating unit in between, and blows the hot air, which has been heated as it passes through the gap in the reflector, toward the conveying section. Equipped with, The sheet drying apparatus according to claim 1, characterized in that the control unit changes the airflow of the hot air fan according to the heating position when the heating position is changed.

9. The aforementioned transport unit is A conveyor belt that suctions and transports the aforementioned sheet, A belt cooling fan for cooling the aforementioned conveyor belt, Equipped with, The sheet drying apparatus according to claim 1, characterized in that the control unit changes the airflow of the belt cooling fan according to the heating position when the heating position is changed.

10. An image forming apparatus that forms an image using a water-containing ink on a sheet, A sheet drying apparatus according to any one of claims 1 to 9, which is connected to the downstream side of the image forming apparatus with respect to the transport direction, An image forming system comprising the following features.

Images