Image forming apparatus

Abstract

To provide an image forming apparatus that can suppress abnormal images such as cockling and curling by controlling the temperature of both the first and second sides of the paper to an appropriate level, thereby enabling the output of stable results. [Solution] To achieve the above objective, an image forming apparatus according to one embodiment of the present invention comprises a printing unit, a heating unit, and a preheating unit. The printing unit is capable of printing on a first surface of a sheet and a second surface of the sheet. The heating unit dries the sheet. The preheating unit is positioned between the printing unit and the heating unit and adjusts the temperature of the sheet. By controlling the temperature of both the first and second surfaces of the paper to an appropriate level, it is possible to suppress abnormal images such as cockling and curling, and to output stable results.

Description

Technical Field

[0001] The present invention relates to an image forming apparatus that dries ink ejected onto a sheet.

Background Art

[0002] After forming an image on paper with ink, it is necessary to dry the ink in order to fix it. However, if the drying speed is high, a difference in moisture content occurs between the area where the ink is applied and the area where the ink is not applied on the paper, resulting in a change in the paper shape such as cockling or curling due to the difference in the expansion and contraction of the paper. Therefore, there is a mechanism for controlling the drying speed by blowing warm air.

[0003] For example, in Patent Document 1, it is proposed to improve the drying property while suppressing the generation of abnormal images by coping with the distortion of the paper with warm air. However, a major replacement is not expected for the second pass that has already passed through the drying section once. Further, in Patent Document 2 and Patent Document 3, it is proposed to cool the paper and further cool the conveyance belt in the double-sided circulation path, but by cooling the second side to the same state as the first side and then reheating and drying the second side again, the drying of the first side is promoted. As a result, cockling and curling are encouraged.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the field of cut sheets, in order to maximize the footprint of the equipment, the sheet is printed on both sides, and once dried, it is passed through the same image formation and drying pass again. As a result, the second side of the sheet passes through the drying section once, and because the temperature of the paper is higher than the first side, heating it again further increases its temperature.

[0006] In view of the above circumstances, the object of the present invention is to provide an image forming apparatus that can suppress abnormal images such as cockling and curling by controlling the temperature of both the first and second sides of the paper to an appropriate level, thereby enabling the output of stable results. [Means for solving the problem]

[0007] To achieve the above objective, an image forming apparatus according to one embodiment of the present invention is provided. The device comprises a printing unit configured to print an image by applying ink to a first surface and a second surface of a sheet, a heating unit for drying the ink applied to the sheet, and a preheating unit positioned between the printing unit and the heating unit to adjust the temperature of the sheet. [Effects of the Invention]

[0008] According to this disclosure, by controlling the temperature of both the first and second sides of the paper to an appropriate level, it is possible to suppress abnormal images such as cockling and curling, and to output stable results.

[0009] Furthermore, the effects described herein are not necessarily limited to those described herein, and may include any of the effects described herein. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the external appearance of the image forming system. [Figure 2] This is a schematic front view showing the configuration of the drying apparatus. [Figure 3] This is a block diagram showing the configuration of the preheating section. [Figure 4] This graph shows an example of the temperature transition of a sheet. [Modes for carrying out the invention]

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0012] First, the overall configuration of the image forming system 100 will be described. Figure 1 is a schematic front view showing the configuration of the image forming system 100. Hereafter, the front side of the page in Figure 1 will be considered the front side of the image forming system 100, and the left and right orientations will be described based on the direction in which the image forming system 100 is viewed from the front side.

[0013] As shown in Figure 1, the image forming system 100 includes a paper feeder 110, an inkjet recording device 1, a drying device 120, and a post-processing device 130. The paper feeder 110 has a large-capacity paper feed deck capable of holding, for example, several thousand sheets S, and supplies the sheets S one by one to the inkjet recording device 1. The inkjet recording device 1 forms an image on the sheets S using an inkjet method. The drying device 120 heats and dries the ink ejected onto the sheets S. The post-processing device 130 performs post-processing on the sheets S on which the image has been formed, such as perforation, stapling, and folding.

[0014] [Inkjet recording device] The inkjet recording device 1 comprises a rectangular parallelepiped main body housing 3. Inside the lower part of the main body housing 3, there is a paper feed cassette 4 for storing sheet-fed paper S such as plain paper or coated paper, and a paper feed roller 5 for feeding the sheets S from the paper feed cassette 4. Above the paper feed cassette 4, there is a first transport unit 7 that picks up the sheets S and transports them in the Y direction as shown in Figure 1. Above the first transport unit 7, there is an image forming unit 6 that ejects ink to form an image.

[0015] Inside the main housing 3, a transport path 10 is provided, which runs from the paper feed roller 5 through the gap between the first transport unit 7 and the image-making unit 6 to the drying device 120. The transport path 10 is mainly formed of plate-shaped members that face each other with a gap between them for the sheet S to pass through. The transport path 10 is provided with transport rollers 17 that grip and transport the sheet S. A registration roller 18 is provided upstream of the image-making unit 6 in the transport direction Y. Above the image-making unit 6, a reversing transport path 10R is provided, which merges with the transport path 10 upstream of the registration roller 18 in the transport direction Y.

[0016] Furthermore, the main housing 3 of the inkjet recording device 1 is provided with an outlet 9 for discharging the sheets S transported by the transport path 10, and a reverse feed opening 29 for guiding the sheets S, which have been dried by the drying device 120, to the reverse transport path 10R. As shown in Figure 1, the reverse feed opening 29 is located above the outlet 9.

[0017] The first conveying unit 7 comprises an endless conveying belt 21, a support plate 23, and a suction unit 24. The conveying belt 21 has numerous ventilation holes (not shown) and is wrapped around a drive roller 25 and a driven roller 22. The support plate 23 has numerous ventilation holes (not shown) and its upper surface is in contact with the inner surface of the conveying belt 21. The suction unit 24 sucks air through the ventilation holes of the support plate 23 and the conveying belt 21, thereby adhering the sheet S to the outer surface of the conveying belt 21. The drive unit (not shown), which includes a motor and a reduction gear, drives the drive roller 25 in a counterclockwise direction in Figure 1, causing the conveying belt 21 to rotate in the counterclockwise direction, and the sheet S adhering to the conveying belt 21 is conveyed in the Y direction.

[0018] The image forming unit 6 includes head units 11Y, 11Bk, 11C, and 11M (hereinafter also collectively referred to as head unit 11). The head unit 11 includes one or more inkjet heads, for example, three inkjet heads arranged in a staggered pattern (not shown). Ink containers 20 filled with yellow, black, cyan, and magenta inks are respectively connected to the head units 11Y, 11Bk, 11C, and 11M.

[0019] The image forming unit 6 also has a drive circuit (not shown) for controlling the amount of ink ejected by the inkjet 11 and a pressurizing element (not shown) for pressurizing the nozzles of the inkjet 11. The drive circuit supplies a discharge signal corresponding to a pixel to the pressurizing element based on the image data from the control unit 2. The pressurizing element pressurizes the nozzles of the yellow, black, cyan, and magenta inks according to the supplied discharge signal.

[0020] The control unit 2 includes an arithmetic unit and a storage unit (not shown). The arithmetic unit is, for example, a CPU (Central Processing Unit). The storage unit includes storage media such as a ROM (Read Only Memory), a RAM (Random Access Memory), and an EEPROM (Electrically Erasable Programmable Read Only Memory). The arithmetic unit performs various processes by reading and executing the control program stored in the storage unit. Note that the control unit 2 may be realized by an integrated circuit that does not use software.

[0021] A display operation unit 19 is provided on the upper part of the main body housing 3. The display operation unit 19 includes a display panel, a touch panel laminated on the display panel, and a keypad (not shown). The control unit 2 causes the display panel to display a screen representing the operation menu and status of the inkjet recording apparatus 1, and controls each part of the inkjet recording apparatus 1 according to the operations detected by the touch panel and the keypad.

[0022] The basic image formation operation (printing on the surface of the sheet S) of the inkjet recording device 1 is as follows: When an image formation job is input to the inkjet recording device 1 from the display operation unit 19 or an external computer, the paper feed roller 5 feeds the sheet S from the paper feed cassette 4 to the transport path 10, and the registration roller 18, whose rotation has been stopped, corrects the skewness of the sheet S. When the registration roller 18 feeds the sheet S to the first transport unit 7 at a predetermined timing, the first transport unit 7 picks up the sheet S on the transport belt 21 and transports it in the Y direction. When the control unit 2 supplies raster-format image data to the drive circuit in synchronization with the transport of the sheet S, the drive circuit supplies ejection signals corresponding to the pixels to the pressure element, ink is ejected from the nozzle, and an image is formed on the sheet S.

[0023] [Drying equipment] Next, the drying apparatus 120 will be described in detail. Figure 2 is a schematic front view showing the configuration of the drying apparatus 120.

[0024] The drying apparatus 120 (see Figure 2) is equipped with a rectangular parallelepiped main housing 31. A second conveying unit 40 is provided slightly above the center of the main housing 31 so as to be aligned with the first conveying unit 7. A heating unit 50 and a preheating unit 60 are provided above the second conveying unit 40. The main housing 31 is equipped with a paper feed opening 32 on the right side and an outlet opening 33 on the left side, and a conveying path 34 is provided from the paper feed opening 32 through the gap between the second conveying unit 40 and the heating unit 50 to the outlet opening 33. Downstream of the second conveying unit 40 in the conveying direction Y, a pair of conveying rollers 35 is provided to convey the sheets S to the post-processing device 130.

[0025] Above the heating unit 50, a reversal transport path 34R is provided, which branches off from the transport path 34 downstream in the transport direction Y from the second transport unit 40 and has a switchback. The main body housing 31 is provided with a reversal discharge port 37 above the paper feed port 32 and opposite the reversal paper feed port 29, for discharging the sheet W transported by the reversal transport path 34R. When performing double-sided printing, the front and back sides of the sheet S are reversed by passing through the reversal transport path 34R and the reversal transport path 10R. In this embodiment, the front surface of the sheet S may be described as the first surface, and the back surface of the sheet S may be described as the second surface.

[0026] Furthermore, the image formation operation on the back surface of the sheet S is as follows: The ink ejected onto the surface of the sheet S is dried by the drying device 120, and the sheet S, with its front and back sides reversed by the reversal transport path 34R and the reversal transport path 10R, is sent to the first transport unit 7 by the register roller 18. The first transport unit 7 picks up the sheet S on the transport belt 21 and transports it in the Y direction. Synchronized with the transported sheet S, the control unit 2 supplies image data to the drive circuit, and the drive circuit supplies an ejection signal corresponding to the pixel to the pressure element, causing ink to be ejected from the nozzle. As a result, an image is formed on the back surface of the sheet S.

[0027] [Heating Unit] The heating unit 50 (see Figure 2) comprises a rectangular parallelepiped housing 51. The lower part of the housing 51 has an opening that corresponds to the size of the entire bottom surface of the rectangular parallelepiped. The housing 51 houses infrared heaters 52 that extend in a front-to-back direction intersecting the transport direction Y. More specifically, it houses a plurality (seven in Figure 2) of rod-shaped infrared heaters 52 with the front-to-back direction as their longitudinal direction. The infrared heaters 52 are, for example, carbon heaters in which a carbon fiber heating element is sealed in a glass tube. The heating element emits infrared rays. The reflector 53 has a concave surface whose cross-section perpendicular to the front-to-back direction is a parabola. The reflector 53 is positioned above the infrared heaters 52 with its concave surface facing downwards.

[0028] The second conveying unit 40 comprises an endless conveying belt 41, a support plate 43, and a suction unit 44. The conveying belt 41 has numerous ventilation holes (not shown) and is wrapped around a drive roller 45 and a driven roller 42. The drive roller 45, the driven roller 42, the support plate 43, and the suction unit 44 are supported by a frame 46. The support plate 43 has numerous ventilation holes (not shown) and its upper surface is in contact with the inner surface of the conveying belt 41. The suction unit 44 sucks air through the ventilation holes of the support plate 43 and the conveying belt 41, thereby causing the sheet S to adhere to the conveying belt 41. The drive unit (not shown), which includes a motor and a reduction gear, drives the drive roller 45 in a counterclockwise direction, causing the conveying belt 41 to rotate counterclockwise, and the sheet S adsorbed to the conveying belt 41 is conveyed in the Y direction. The upper surface of the conveying belt 41 (the surface facing the heating unit 50) is part of the conveying path 34.

[0029] To fix the ink dispensed onto the sheet S, the sheet S is heated by the heating unit 50, causing the surface temperature of the sheet S to rise. This temperature rise results in differences in the amount of moisture between the ink-coated and uncoated areas of the paper, causing expansion and contraction. In other words, problems such as cockling and curling of the paper shape occur.

[0030] Therefore, in this embodiment, a preheating unit 60 is provided to adjust the temperatures of the front and back surfaces of the sheet S before the temperature of the sheet S rises due to the heating unit 50.

[0031] [Preheating section] As shown in Figure 2, the preheating unit 60 is positioned between the image-making unit 6 and the heating unit 50 to adjust the temperature of the sheet S. In Figure 2, it is positioned upstream of the heating unit 50 in the transport direction Y within the main housing 31 of the drying apparatus 120, and adjusts the temperature of the sheet S before it is heated by the heating unit 50.

[0032] Figure 3 is a block diagram showing the configuration of the preheating unit 60. As shown in Figure 3, the preheating unit 60 includes a hot air supply unit 61, a cold air supply unit 62, and a temperature control unit 63.

[0033] The hot air supply unit 61 heats the sheet S. For example, the hot air supply unit 61 may use an infrared heater or a blower fan to send out the hot air heated by the heater.

[0034] The cool air supply unit 62 cools the sheet S. For example, the cool air supply unit 62 may be a blower fan or the like. Alternatively, a blower fan and a cooling plate for cooling the air supplied to the blower fan may be combined.

[0035] The temperature control unit 63 adjusts the temperature of the sheet S. In this embodiment, the temperature control unit 63 adjusts the temperature of the air supplied to the sheet S by adjusting the amount of cold air output from the cold air supply unit and the amount of hot air output from the hot air supply unit.

[0036] Furthermore, the arrangement and number of the hot air supply unit 61 and the cold air supply unit 62 are not limited. For example, the hot air supply unit 61 and the cold air supply unit 62 may be arranged sequentially along the conveying direction Y. Alternatively, multiple cold air supply units 62 may be arranged for one hot air supply unit 61. In addition, the method of blowing hot air or cold air onto the sheet S is not limited. The hot air supplied from the hot air supply unit 61 and the cold air supplied from the cold air supply unit 62 may be combined and blown through a single path (pipe), or the air may be blown using louvers that can adjust the direction of the hot or cold air in accordance with the movement of the sheet S.

[0037] Hereinafter, the space (region) heated by the preheating unit 60 will be referred to as the preheating space. For example, the space from after image formation by ink ejection to the point where the sheet reaches the heating unit 50 is the preheating space. In Figure 2, the preheating space refers to the space directly below the preheating unit 60. In addition, the preheating space may also include the space downstream of the image-making unit 6 in the transport direction Y. That is, the preheating unit 60 may be located in the inkjet recording device 1. Furthermore, multiple preheating units 60 may be located between the image-making unit 6 and the heating unit 50. For example, the temperature of the sheet S may be regulated by a first preheating unit located downstream of the image-making unit 6 in the transport direction Y and a second preheating unit located upstream of the heating unit 50 in the transport direction Y.

[0038] Here, the temperature transitions during the printing of the front and back surfaces of sheet S will be explained using Figure 4.

[0039] Figure 4 is a graph showing an example of the temperature transition of sheet S. In Figure 4, the horizontal axis represents time, and the vertical axis represents the temperature of sheet S. Here, t0 on the horizontal axis represents the time before sheet S is printed by the imaging unit 6.

[0040] As shown in Figure 4, from time t0 to time t1, the temperature of the surface of sheet S decreases as ink is applied to the surface of sheet S. That is, time t1 indicates the time when sheet S has passed through the printing unit 6 (when printing on the surface of sheet S is completed).

[0041] From time t1 to time t2, the surface of sheet S enters the preheating space, causing the temperature of the sheet S surface to rise due to the preheating unit 60. That is, time t2 indicates the time when the surface of sheet S passes through the preheating space. The temperature of the sheet S surface at time t2 will be referred to as the first temperature.

[0042] From time t2 to time t3, the surface of sheet S is heated by the heating unit 50, and the temperature of the sheet S surface rises. That is, time t3 indicates the time when the sheet S has passed through the heating unit 50. At time t3, the temperature of the sheet S surface reaches the drying temperature.

[0043] The drying temperature is the heating temperature of the sheet S in the heating unit 50. For example, the drying temperature is the temperature at which the temperature of the sheet S is expected to rise as it passes through the heating unit 50. Specifically, the drying temperature is the temperature that is expected to be based on at least one of the amount of heat emitted from the heating unit 50, the length of the heating unit 50 in the transport direction Y, or the time it takes for the sheet S to pass through the heating unit 50. In other words, the drying temperature can also be said to be the temperature of the sheet S when it has passed through the heating unit 50, or the temperature of the sheet S when the ejected ink has dried and image formation is complete.

[0044] Between time t3 and time t4, the front and back sides of the sheet S are reversed by the reversal transport path 34R and the reversal transport path 10R, and the temperature of the sheet S decreases as it is transported until the ink is ejected by the printing unit 6. In other words, time t4 represents the time just before the back side of the sheet S is printed by the printing unit 6.

[0045] Between time t4 and time t5, ink is applied to the back surface of sheet S, causing the temperature of the back surface of sheet S to decrease. In other words, time t5 indicates the time when sheet S has passed through the printing unit 6 (when printing on the back surface of sheet S is complete).

[0046] Between time t5 and time t6, the back surface of sheet S enters the preheating space, causing the temperature of the back surface of sheet S to rise due to the preheating unit 60. In other words, time t6 indicates the time when the back surface of sheet S passes through the preheating space. The temperature of the back surface of sheet S at time t6 corresponds to the second temperature.

[0047] Furthermore, from time t6 onward, the back surface of sheet S is heated by the heating unit 50, causing the back surface of sheet S to rise. This completes the double-sided printing of sheet S, and sheet S is discharged from the discharge port 33 and transported to the post-processing device 130.

[0048] In other words, the temperature control unit 63 heats the surface of the sheet S to a first temperature which is a predetermined temperature lower than the drying temperature. For example, the temperature control unit 63 adjusts the temperature of the surface of the sheet S (the temperature of the sheet S at time t1) to rise so that the first temperature is a predetermined temperature lower than the drying temperature of the sheet S heated by the heating unit 50.

[0049] Specifically, the temperature control unit 63 preheats the sheet S gently (corresponding to time t1 to time t2 in Figure 4) in order to suppress the rapid temperature rise of the sheet S due to heating by the heating unit 50 on the surface of the sheet S (the side that was printed first), and to suppress the amount of change over time in the moisture content, drying rate, and ink properties of the sheet S that accompanies the temperature rise. In other words, the first temperature of the sheet S is adjusted so that the change between the temperature of the sheet S surface at time t1 and the drying temperature at time t3 is gradual.

[0050] Furthermore, when the back side of the sheet S is heated to print an image, the temperature control unit 63 adjusts the second temperature so that the second temperature, which is the temperature of the back side of the sheet S, becomes the first temperature. Specifically, the temperature control unit 63 controls the temperature of the back side of the sheet S (the second temperature at time t6 in Figure 4) so ​​that it becomes the temperature of the surface of the sheet S, which has been controlled in the preheating space (corresponding to the first temperature at time t2 in Figure 4).

[0051] In this embodiment, the temperature control unit 63 adjusts the amount of cold air and hot air to bring the temperature of the back surface of the sheet S to the optimal temperature before drying by the heating unit 50, based on the relationship between a first temperature based on printing information relating to the printing of the surface of the sheet S and the time until the back surface of the sheet S is printed, or the temperature decrease due to printing on the back surface of the sheet S (amount of heat removed by the image-forming ink), which is derived from this relationship.

[0052] Here, the time until the back side of sheet S is printed corresponds to the transition from time t3 to time t4. Also, the temperature decrease due to printing on the back side of sheet S (the amount of heat removed by the ink for image formation) corresponds to the temperature transition from time t4 to time t5.

[0053] Print information includes the paper size, paper type, or ink volume of the formed image of sheet S. The ink volume of the formed image can also be considered the amount of heat retained by sheet S after drying, based on the amount of ink used.

[0054] In other words, the preheating unit 60 aims to eliminate the difference in drying speed between the first heated surface of the sheet S and the back surface of the sheet S, which is heated during double-sided printing, by controlling the temperature of the back surface of the sheet S. The temperature of the back surface of the sheet S is not always constant from the time the surface is dried until it is dried again by the drying device 120. For example, the temperature of the back surface of the sheet S may differ depending on the amount of ink applied, the paper size, the media, the drying settings, etc. Therefore, the preheating unit 60 has a mechanism to adjust the output of hot or cold air so that the back surface of the sheet S is at the same temperature as the surface while the sheet S passes through the preheating space.

[0055] For example, let's assume the temperature when sheet S enters the preheating space is 25°C, which is the ambient temperature minus the heat absorbed by the ink (see time t1 in Figure 4). In this case, if the heating unit 50 heats sheet S to 60°C (see time t3 in Figure 4), the temperature control unit 63 will output warm air so that sheet S reaches a temperature of 40°C to 50°C by the time it passes through the preheating space (see times t1 to t2 in Figure 4).

[0056] In this example, the drying temperature is 60°C and the first temperature is 40°C to 50°C, so the predetermined temperature is 10°C to 20°C. The predetermined temperature may be set arbitrarily. For example, it may be set based on the printing information when the surface of sheet S is printed, or it may be set based on known values ​​corresponding to the amount of ink applied to sheet S and the time until heating. Furthermore, if the first temperature exceeds the drying temperature, the difference may be set as the predetermined temperature and cooled in a preheating space.

[0057] For example, suppose the back surface of sheet S reaches 60°C after being dried by the heating unit 50. In this case, the temperature of the back surface of sheet S is controlled so that the surface of sheet S reaches the temperature controlled in the preheating space (40°C to 50°C in the above example). Specifically, if the temperature of the back surface of sheet S (temperature at time t5 in Figure 4) is assumed to be 60°C, the preheating unit 60 controls the temperature by increasing the amount of cold air so that the temperature of the back surface of sheet S drops by 15°C. Similarly, if the temperature of the back surface of sheet S is assumed to be 30°C (temperature at time t5 in Figure 4), the preheating unit 60 controls the temperature by increasing the amount of hot air so that the temperature of the back surface of sheet S rises by 15°C.

[0058] The method of temperature control for the sheet S by the preheating unit 60 is not limited. For example, a sensor may be provided to detect the temperature of the sheet S before it enters the preheating space. In this case, information regarding the detected temperature of the sheet S is supplied to the control unit 2, and the amount of hot and cold air output from the preheating unit 60 may be controlled by the temperature control unit 63 based on the signal from the control unit 2. In addition, the temperature control may be controlled according to a predetermined table based on the amount of ink discharged onto the sheet S, the amount of heat absorbed by the ink, or the time from when the surface of the sheet S is dry until the back side of the sheet S is printed.

[0059] The configuration of the drying apparatus 120 is not limited. For example, it may have a display unit that allows the user to check the printing result of the first side (front side), and an operation unit that allows the user to adjust the temperature of the air supplied to the preheating unit 60 for the second side (back side) of the paper based on the printing result of the first side. In this case, the user can input the temperature of the air supplied from the preheating unit 60 via the operation unit from the printing result of the first side displayed on the display unit. Alternatively, a control signal may be supplied to the temperature control unit 63 from the temperature input by the user, and the temperature control unit 63 may adjust the temperature. Furthermore, the above functions may be realized by the display operation unit 19 and the control unit 2.

[0060] Furthermore, the preheating section 60 may be used not only for double-sided printing of the sheet, but also for single-sided printing only.

[0061] According to this embodiment, the preheating unit 60 is positioned between the printing unit 6, which can print on both the front and back surfaces of the sheet S, and the heating unit 50, which dries the sheet S, and adjusts the temperature of the sheet S. This allows the temperature of the front surface of the sheet S after passing through the preheating space to be controlled to be approximately the same as the temperature of the back surface of the sheet S. Therefore, according to this embodiment, by controlling the temperature of both the first and second surfaces of the paper to an appropriate level, abnormal images such as cockling and curling can be suppressed, and stable output can be produced.

[0062] Although various embodiments and modifications of this technology have been described above, this technology is not limited to the embodiments described above, and various modifications can be made without departing from the gist of this technology. [Explanation of Symbols]

[0063] 1… Inkjet recording device 6…Image creation unit 40…Transport Unit 50…Heating unit 60… Preheating section 61...Temperature Control Unit 62...Cold air supply section 63...Temperature Control Unit 100…Image forming systems

Claims

1. A printing unit configured to print an image by applying ink to a first surface of a sheet and a second surface of the sheet, A drying section for drying the ink applied to the sheet, A preheating unit is positioned between the printing unit and the drying unit to adjust the temperature of the sheet. An image forming apparatus comprising the following:

2. An image forming apparatus according to claim 1, The preheating unit includes a cold air supply unit for cooling the sheet and a hot air supply unit for heating the sheet. Image forming apparatus.

3. An image forming apparatus according to claim 2, The preheating unit further includes a temperature control unit that adjusts the temperature of the air supplied to the sheet by adjusting the amounts of cold air output from the cold air supply unit and hot air output from the hot air supply unit. Image forming apparatus.

4. An image forming apparatus according to claim 3, When heating the image printed on the first surface, the temperature control unit heats the first surface to a first temperature which is a predetermined temperature lower than the drying temperature which is the heating temperature of the sheet in the drying section. When heating the image printed on the second surface, the temperature control unit adjusts the second temperature such that the second temperature which is the temperature of the second surface becomes equal to the first temperature. Image forming apparatus.

5. The image forming apparatus according to claim 4, further, The device is equipped with an operating unit that allows the user to change the second temperature. Image forming apparatus.

Images