Image forming apparatus, control method, and storage medium

Abstract

To discharge a sheet in a state where the sheet is not curled and irregularity of the sheet hardly occurs.SOLUTION: The image forming apparatus 1 includes a discharge unit 9 that discharges sheets one by one, a discharge tray 10 on which the sheets discharged from the discharge unit 9 are stacked one by one, an air blowing unit 40 that blows air to the sheets discharged from the discharge unit 9, and a control unit 5 that controls the amount of air blown by the air blowing unit 40. The control unit 5 sets the amount of air blown by the air blowing unit 40 when the leading edge of the sheet is discharged from the discharge unit 9 to a first air blowing amount, and changes the amount of air blown by the air blowing unit 40 to a second air blowing amount smaller than the first air blowing amount when the trailing edge of the sheet is discharged from the discharge unit 9.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus, a control method, and a program, and more particularly to a technique for discharging a sheet on which an image has been formed onto a tray. [Background technology]

[0002] In image forming devices such as MFPs (Multifunction Peripherals), sheets with images formed on them are ejected onto a paper output tray. When a sheet is ejected from the image forming device, its leading edge hangs down. If the contact angle between the sheet and the paper output tray is large, the leading edge of the sheet will get caught on the surface of the paper output tray, making it difficult for the sheet to slide. When the trailing edge of the sheet is sequentially ejected from the image forming device in this state, the leading edge of the sheet will curl. As a result, the sheet will not be properly placed on the paper output tray.

[0003] Furthermore, if there are already sheets ejected onto the ejection tray, the leading edge of the drooping sheet may get caught on the topmost sheet on the ejection tray. In this case, the sheet ejected from the image forming device may push the topmost sheet off the tray. This causes the problem that multiple sheets ejected from the image forming device are not aligned on the ejection tray.

[0004] To prevent the above-mentioned problems, there is a method for adding stiffness to the sheet discharged from the image forming apparatus. For example, by providing an uneven shape in the axial direction of the discharge roller that discharges the sheet, a wavy shape is formed in the discharged sheet, and stiffness is added to the sheet. Increasing the step of the uneven shape increases the wavy shape, and the stiffness added to the sheet becomes even stronger. This can suppress sagging of the leading edge of the sheet.

[0005] However, providing an uneven surface on the discharge roller to form a wavy shape on the sheet can cause damage to the sheet depending on the type of sheet. Damage to the sheet is particularly severe when the sheet is cardboard. Therefore, when the sheet is cardboard, it is necessary to reduce the wavy shape imparted to the sheet. However, a configuration that changes the wavy shape depending on the type of sheet leads to an increase in size and cost of the image forming apparatus.

[0006] Conventionally, an image forming apparatus has been proposed that discharges a sheet without imparting a wavy shape to the sheet (see, for example, Patent Document 1). This image forming apparatus has an air outlet below the discharge roller, and blows air from the air outlet toward the downstream side in the sheet discharge direction. That is, this image forming apparatus starts blowing air when the leading edge of the discharged sheet contacts the paper output tray, thereby lifting the drooping leading edge of the sheet. Then, when the trailing edge of the sheet passes through the discharge roller, the image forming apparatus increases the amount of air blown compared to before. However, this conventional image forming apparatus has the following problems.

[0007] The leading edge of a sheet begins to droop immediately after it is ejected from the ejection roller. As the drooping rate increases, the contact point between the leading edge of the sheet and the output tray becomes closer to the ejection roller, increasing the contact angle between the sheet and the output tray. As a result, the leading edge of the sheet may get caught on the surface of the output tray when it contacts the output tray. For this reason, conventional image forming devices may not be able to properly lift the leading edge of the sheet even if they start blowing air at the time the leading edge of the sheet contacts the output tray. As a result, the sheet may end up being stacked on the output tray in a curled state.

[0008] Furthermore, if the airflow volume is increased just as the trailing edge of the sheet passes through the discharge roller, the trailing edge of the sheet is lifted. This increases the time it takes for the trailing edge of the sheet to land on the paper output tray. The sheet, subjected to buoyancy by the airflow, behaves unstably until it lands, which increases the likelihood of the sheet becoming misaligned. In particular, because conventional image forming devices blow air downstream in the sheet discharge direction, the discharged sheet is carried downstream by the wind, making it more likely for the sheet to become misaligned. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-169998 Summary of the Invention [Problem to be solved by the invention]

[0010] The present invention has been made to solve the above-mentioned problems of the conventional art, and an object of the present invention is to provide an image forming apparatus, a control method, and a program that can discharge sheets without curling the sheets and in a state where the sheets are less likely to become misaligned. [Means for solving the problem]

[0011] In order to achieve the above object, the invention of claim 1 is an image forming apparatus comprising: a discharge section that discharges sheets one by one; an output tray that stacks the sheets discharged from the discharge section one by one; an air blowing section that blows air onto the sheets discharged from the discharge section; and a control section that controls the amount of air blown by the air blowing section, wherein the control section sets the amount of air blown by the air blowing section to a first air blowing volume when the leading end of the sheet is discharged from the discharge section, and changes the amount of air blown by the air blowing section to a second air blowing volume that is smaller than the first air blowing volume when the trailing end of the sheet is discharged from the discharge section.

[0012] The invention of claim 2 is characterized in that, in the image forming apparatus of claim 1, the blowing section has an air outlet that opens below the discharge section and blows air upward from the air outlet.

[0013] The invention according to claim 3 is the image forming apparatus according to claim 1, wherein the air blowing section blows air toward the lower surface of the sheet discharged from the discharge section.

[0014] The invention of claim 4 is characterized in that, in the image forming apparatus of claim 1, the output tray has an inclined surface whose height gradually increases in the sheet transport direction, and the inclination angle of the inclined surface increases as it approaches the output section.

[0015] The invention according to claim 5 is the image forming apparatus according to claim 4, characterized in that the air blowing section is provided in a space below the inclined surface.

[0016] The invention of claim 6 is characterized in that, in the image forming apparatus of claim 1, the control unit determines the first air flow rate and the second air flow rate according to the attributes of the sheet discharged from the discharge unit.

[0017] The invention of claim 7 is an image forming apparatus of claim 6, further comprising an attribute detection sensor provided in the transport path along which the sheet is transported, which detects the attributes of the sheet transported along the transport path, and the control unit is configured to determine the first air flow rate and the second air flow rate based on the attribute of the sheet detected by the attribute detection sensor.

[0018] The invention of claim 8 is characterized in that in the image forming apparatus of claim 1, the control unit determines the first air flow rate and the second air flow rate according to job settings.

[0019] The invention according to claim 9 is the image forming apparatus according to claim 8, wherein the job settings include settings for double-sided printing or single-sided printing on sheets.

[0020] The invention of claim 10 is characterized in that, in the image forming apparatus of claim 1, it further comprises an environmental sensor that acquires environmental information related to temperature or humidity, and the control unit determines the first airflow volume and the second airflow volume according to the environmental information.

[0021] The invention of claim 11 is characterized in that, in the image forming apparatus of claim 1, the control unit counts the number of sheets stacked in the output tray and determines the first air flow rate and the second air flow rate according to the number of sheets stacked.

[0022] The invention of claim 12 is an image forming apparatus of claim 1, further comprising a sheet detection sensor provided in the conveying path along which the sheet is conveyed, for detecting the sheet, and the control unit is configured to predict the timing at which the leading or trailing end of the sheet will be discharged from the discharge unit based on the detection result of the sheet by the sheet detection sensor.

[0023] The invention of claim 13 is characterized in that in the image forming apparatus of claim 1, the control unit stops driving the blower unit when the rear end of the sheet is discharged from the discharge unit.

[0024] The invention of claim 14 is characterized in that, in the image forming apparatus of claim 1, the blower section has a first fan and a second fan, and the control section drives both the first fan and the second fan when the leading end of the sheet is discharged from the discharge section, and stops driving one of the first fan and the second fan when the trailing end of the sheet is discharged from the discharge section.

[0025] The invention of claim 15 is characterized in that, in the image forming apparatus of claim 1, the control unit stops driving the air blowing unit after a predetermined time has elapsed since changing the air blowing volume by the air blowing unit to a second air blowing volume that is smaller than the first air blowing volume.

[0026] The invention of claim 16 is a control method for an image forming device having an ejection section that ejects sheets one by one, an output tray that stacks the sheets ejected from the ejection section one by one, and an air blowing section that blows air onto the sheets ejected from the ejection section, characterized in that when the leading end of the sheet is ejected from the ejection section, the air blowing volume by the air blowing section is set to a first air blowing volume, and when the trailing end of the sheet is ejected from the ejection section, the air blowing volume by the air blowing section is changed to a second air blowing volume that is smaller than the first air blowing volume.

[0027] The invention of claim 17 is a program executed in an image forming device having an ejection section that ejects sheets one by one, an output tray that stacks the sheets ejected from the ejection section one by one, and an air blowing section that blows air onto the sheets ejected from the ejection section, characterized in that the program causes the image forming device to execute a first step of setting the air blowing volume of the air blowing section to a first air blowing volume when the leading end of the sheet is ejected from the ejection section, and a second step of changing the air blowing volume of the air blowing section to a second air blowing volume that is less than the first air blowing volume when the trailing end of the sheet is ejected from the ejection section. [Effects of the Invention]

[0028] According to the present invention, it is possible to discharge a sheet on which an image is formed without curling the sheet and in a state where the sheet is less likely to become misaligned. [Brief explanation of the drawings]

[0029] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of an image forming apparatus. [Figure 2] FIG. 2 is an enlarged cross-sectional view showing a discharge section and a paper discharge tray. [Figure 3]FIG. 2 is a block diagram showing the functional configuration of a control unit that controls the air blower unit. [Figure 4] 10A and 10B are diagrams illustrating the behavior of a sheet discharged from a discharge section. [Figure 5] 10A and 10B are diagrams illustrating the behavior of a sheet discharged from a discharge section. [Figure 6] FIG. 10 is a diagram illustrating an example of control information. [Figure 7] FIG. 10 is a diagram showing a state in which a plurality of sheets are stacked on a paper discharge tray. [Figure 8] FIG. 10 is a diagram illustrating an example of correction information. [Figure 9] 10 is a flowchart illustrating an example of a main processing procedure performed by a control unit. [Figure 10] 10 is a flowchart illustrating an example of a detailed processing procedure of an airflow amount determination process. [Figure 11] 10 is a flowchart showing an example of a detailed processing procedure of an air blowing control process. [Figure 12] FIG. 10 is an enlarged cross-sectional view showing a paper discharge tray in a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0030] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. Elements common to the embodiments described below are designated by the same reference numerals, and redundant description thereof will be omitted.

[0031] (First embodiment) FIG. 1 is a diagram showing a schematic configuration of an image forming apparatus 1 according to a first embodiment of the present invention. This image forming apparatus 1 is configured as, for example, an MFP and has scanning and printing functions. The image forming apparatus 1 has a scanner unit 2 at the top of the apparatus body, which reads an image of a document set by a user. The image forming apparatus 1 also has a printer unit 3 at the bottom of the apparatus body, which forms and outputs an image on a sheet 12 such as printing paper. The printer unit 3 forms and outputs an image on the sheet 12 using, for example, an electrophotographic method. The image forming apparatus 1 also has an operation panel 4 on the front side of the top of the apparatus body. The operation panel 4 is a user interface for a user who uses the image forming apparatus 1. For example, the image forming apparatus 1 receives job setting operations and job execution instructions from the user via the operation panel 4.

[0032] The printer unit 3 includes a control unit 5, a paper feed conveyance unit 6, an image forming unit 7, a fixing unit 8, a discharge unit 9, and a paper discharge tray 10. The control unit 5 controls the operation of each unit in the image forming apparatus 1. For example, the control unit 5 accepts job setting operations by a user via the operation panel 4 and sets the job specified by the user. When the user instructs the control unit 5 to execute a job, the control unit 5 controls the operation of each unit in the printer unit 3 to form and output the image to be printed on a sheet 12. The control unit 5 is also connected to a network such as a LAN (Local Area Network) and is capable of receiving print jobs via the network. Upon receiving a print job, the control unit 5 reflects the settings specified in the print job and executes the print job.

[0033] Inside the printer unit 3, there are formed paper feed cassettes 11, 11 that store multiple sheets 12, and a transport path 15 that transports the sheets 12. The paper feed transport unit 6 feeds a sheet 12 from any one of the multiple paper feed cassettes 11, 11, and transports the sheet 12 along the transport path 15. For example, the multiple paper feed cassettes 11, 11 may each store sheets 12 of different types or sizes.

[0034] The paper feed conveying unit 6 includes a pickup roller 13 and a paper feed roller 14 provided in each of the multiple paper feed cassettes 11. The pickup roller 13 feeds the top sheet 12 of the stack of sheets stored in the paper feed cassette 11 toward the paper feed roller 14. When multiple sheets 12 are fed by the pickup roller 13, the paper feed roller 14 separates the topmost sheet 12 from the second and subsequent sheets 12 and feeds only the first sheet 12 toward the conveying path 15. The paper feed conveying unit 6 conveys the sheet 12 supplied to the conveying path 15 in the direction of arrow F2. The conveying path 15 is provided with an attribute detection sensor 16, a timing roller 17, a secondary transfer roller 18, a fixing unit 8, and an ejection unit 9.

[0035] The attribute detection sensor 16 detects the sheet 12 being transported along the transport path 15. The attribute detection sensor 16 detects the attribute of the sheet 12 by irradiating the sheet 12 with a predetermined light and detecting the light reflected from the surface of the sheet 12 and the light transmitted through the sheet 12. The attributes of the sheet 12 include the type, name, size, etc. of the sheet 12. The types of the sheet 12 include plain paper, recycled paper, cardboard, thin paper, etc. For example, the control unit 5 can identify the attribute of the sheet 12 being transported along the transport path 15 based on the attribute detection signal output from the attribute detection sensor 16.

[0036] When attribute detection sensor 16 detects the leading edge of sheet 12, control unit 5 temporarily stops conveying sheet 12 by paper feed conveying unit 6 at the timing when the leading edge of sheet 12 reaches the nip portion of timing roller 17. Then, control unit 5 drives timing roller 17 to coincide with the timing when the image formed by image forming unit 7 reaches secondary transfer roller 18, and resumes conveying sheet 12 by paper feed conveying unit 6. As a result, the image is secondarily transferred onto sheet 12 when sheet 12 passes secondary transfer roller 18.

[0037] The image forming unit 7 has an intermediate transfer belt 26. The intermediate transfer belt 26 is an endless belt that is stretched over a drive roller 27 and a driven roller 28. When the drive roller 27 rotates in a predetermined direction, the intermediate transfer belt 26 circulates in the direction indicated by the arrow F1. Below the intermediate transfer belt 26, multiple image forming units 20Y, 20M, 20C, and 20K are provided, each corresponding to a different color: Y (yellow), M (magenta), C (cyan), and K (black).

[0038] The image forming units 20Y, 20M, 20C, and 20K form toner images of the respective colors Y, M, C, and K and perform primary transfer onto the intermediate transfer belt 26. For example, the image forming unit 20Y includes a photosensitive drum 21, a charger 22, an exposure unit 23, a developing unit 24, and a cleaner 25. The photosensitive drum 21 is a drum-shaped image carrier with a photosensitive layer formed on its surface. The charger 22 charges the surface of the photosensitive drum 21 to a predetermined charge. The exposure unit 23 exposes the surface of the photosensitive drum 21 to light to form an electrostatic latent image. The developing unit 24 applies a developer containing toner to the surface of the photosensitive drum 21 and develops the electrostatic latent image with the toner. The other image forming units 20M, 20C, and 20K have a similar configuration.

[0039] The intermediate transfer belt 26 is pressed against the surface of the photosensitive drum 21 by the primary transfer roller 29. A predetermined potential is applied to the primary transfer roller 29, which performs primary transfer of the toner image formed on the surface of the photosensitive drum 21 onto the intermediate transfer belt 26.

[0040] Image forming units 20Y, 20M, 20C, and 20K perform primary transfer, superimposing toner images of each color onto intermediate transfer belt 26. Therefore, when the sheet passes one of image forming units 20K, which is the most downstream, a color image is formed on the surface of intermediate transfer belt 26. This color image is secondarily transferred, at the position of secondary transfer roller 18, onto sheet 12 sent out from timing roller 17.

[0041] A fixing unit 8 is provided downstream of the secondary transfer roller 18. The fixing unit 8 applies heat and pressure to the sheet 12 onto which the toner image is transferred, thereby fixing the image to the sheet 12. The optimum fixing temperature when the heat treatment is performed in the fixing unit 8 varies depending on the type of sheet 12. Therefore, the control unit 5 identifies the type of sheet 12 based on the attribute of the sheet 12 detected by the attribute detection sensor 16, and controls the fixing temperature to an optimum temperature.

[0042] The sheet 12 that has passed through the fixing unit 8 is guided to the discharge unit 9. The discharge unit 9 discharges the sheet 12 to a discharge tray 10 provided above the printer unit 3. However, if double-sided printing is specified in the job settings, the discharge unit 9 supplies the sheet 12 supplied from the fixing unit 8 to a reversal path 15r. The reversal path 15r is a path that turns over the sheet 12 with an image formed on one side and supplies it again to the timing roller 17. The sheet 12 is guided again through the reversal path 15r to the secondary transfer roller 18 and the fixing unit 8, whereby images are formed on both sides of the sheet 12. The discharge unit 9 discharges the sheet 12 with images formed on both sides to a discharge tray 10.

[0043] The discharge tray 10 is provided in the body space of the image forming apparatus 1 between the scanner unit 2 and the printer unit 3. The discharge unit 9 includes discharge rollers 30 and a discharge opening 31 formed in a wall portion facing the discharge tray 10. A sheet detection sensor 19 is provided in the transport path 15 that transports the sheet 12 to the discharge unit 9. The sheet detection sensor 19 is provided at a predetermined position upstream of the discharge rollers 30. The discharge rollers 30 have a nip portion formed by joining a pair of rollers, and by rotating in a predetermined direction with the sheet 12 sandwiched in the nip portion, the sheet 12 is discharged from the discharge opening 31 onto the discharge tray 10. The discharge rollers 30 discharge the sheet 12 in a flat state without imparting any undulations to the sheet 12.

[0044] FIG. 2 is an enlarged cross-sectional view showing the discharge section 9 and the paper output tray 10. The paper output tray 10 has a sheet loading section 50, which is formed by raising the upper surface of the printer unit 3. The sheet loading section 50 is low near the discharge section 9 and gradually becomes higher as it moves away from the discharge section 9. That is, the upper surface of the sheet loading section 50 is formed as an inclined surface 51 that gradually increases in height in the discharge direction of the sheet 12. The inclined surface 51 has different inclination angles along the discharge direction of the sheet 12. For example, in the sheet loading section 50 of this embodiment, the inclination angle of the inclined surface 51 changes in three stages in the discharge direction of the sheet 12. The inclined surface 51 closest to the discharge section 9 is formed as a first inclined surface 51a having a first inclination angle. The central inclined surface 51 is formed as a second inclined surface 51b having a second inclination angle smaller than the first inclination angle. Furthermore, the inclined surface 51 located farthest from the discharge unit 9 is formed as a third inclined surface 51c having a third inclination angle that is even smaller than the second inclination angle. An end of the first inclined surface 51a is connected to a duct 53. An end of the third inclined surface 51c is connected to a wall portion 52 erected on the upper surface of the printer unit 3.

[0045] As shown in FIG. 2 , the discharge port 31 opens at the same height as the second inclined surface 51b. Therefore, if the leading edge of the sheet 12 does not droop, the leading edge of the sheet 12 discharged from the discharge section 9 contacts the second inclined surface 51b at a position relatively far from the discharge port 31. However, in reality, the leading edge of the sheet 12 discharged from the discharge section 9 droops or curls. Therefore, the position where the leading edge of the sheet 12 contacts the inclined surface 51 moves closer to the discharge port 31. As the contact position moves closer to the discharge port 31, the contact angle between the leading edge of the sheet 12 and the inclined surface 51 increases. As a result, the leading edge of the sheet 12 is more likely to get caught on the inclined surface 51. The image forming apparatus 1 of this embodiment is provided with a blower 40 to prevent the leading edge of the sheet 12 from getting caught on the inclined surface 51 when the sheet 12 is discharged.

[0046] The inside of the sheet placement section 50 is hollow. The air blowing section 40 is provided in this hollow. The air blowing section 40 has a fan 41. The fan 41 is driven by the control section 5. The air blowing section 40 uses the inner space of the sheet placement section 50 as a duct 42 and sends air generated by the fan 41 toward the discharge section 9. An air vent 43 is provided in the wall section 52. When the fan 41 is driven, air flows into the sheet placement section 50 through the air vent 43, generating air inside the sheet placement section 50 in the direction indicated by the arrow. This air is guided from inside the sheet placement section 50 to inside the duct 53. The duct 53 has an air outlet 44 that opens below the discharge section 9. The air blowing section 40 blows air from the air outlet 44. In other words, the air blowing section 40 is configured to blow air upward from a position below the discharge section 9. Therefore, the air blowing section 40 can blow air upward toward the lower surface of the sheet 12 discharged from the discharge section 9, thereby lifting the sheet 12.

[0047] In this embodiment, as described above, an example is given in which the air blowing unit 40 is provided inside the sheet loading unit 50. However, the location where the air blowing unit 40 is provided is not limited to inside the sheet loading unit 50. That is, the air blowing unit 40 may be provided in any location as long as it can blow air upward from a position below the discharge unit 9. Therefore, the air blowing unit 40 may be provided in a location other than inside the sheet loading unit 50. However, if the air blowing unit 40 is provided in a location other than inside the sheet loading unit 50, it is necessary to secure installation space for the air blowing unit 40 inside the device body, which may increase the size of the device body. In order to prevent the device body from becoming larger, it is preferable to provide the air blowing unit 40 inside the sheet loading unit 50, as shown in FIG. 2.

[0048] 3 is a block diagram showing the functional configuration of the control unit 5 that controls the blower 40. The control unit 5 includes a CPU 60 and a storage unit 61. The CPU 60 is a hardware processor that reads and executes a computer-readable program 62 stored in the storage unit 61. The storage unit 61 is a non-volatile storage device configured from a hard disk drive (HDD), a solid state drive (SSD), or the like. The storage unit 61 stores the program 62, control information 63, and correction information 64.

[0049] By executing the program 62, the CPU 60 functions as a job setting unit 71, a job control unit 72, an attribute acquisition unit 73, an environmental information acquisition unit 74, an airflow amount determination unit 75, a position detection unit 76, and a fan driving unit 77.

[0050] The job setting unit 71 accepts a user's job setting operation via the operation panel 4, for example, and sets the setting values ​​specified by the user to various setting items that are applied when the job is executed. When the user instructs the job to be executed, the job setting unit 71 activates the job control unit 72. The job setting unit 71 also outputs setting information in which the values ​​specified by the user have been set to the airflow volume determination unit 75.

[0051] When a user instructs the job to be executed, the job control unit 72 drives the paper feed conveyance unit 6 and the image forming unit 7 and starts the job execution. The job control unit 72 controls the job execution in a state that reflects the job settings set by the job setting unit 71. For example, if double-sided printing is specified in the job settings, the job control unit 72 forms an image on one side of the sheet 12, then conveys the sheet 12 to the reversing path 15r, forms an image on the other side of the sheet 12, and discharges the sheet 12.

[0052] When the job control unit 72 starts executing the job, the CPU 60 causes the attribute acquisition unit 73, the environmental information acquisition unit 74, the airflow amount determination unit 75, the position detection unit 76, and the fan drive unit 77 to function.

[0053] The attribute acquisition unit 73 acquires, from the attribute detection sensor 16, information about the attributes of the sheet 12 detected when the fed sheet 12 passes the position of the attribute detection sensor 16. The attribute acquisition unit 73 identifies the type, name, and size of the fed sheet 12 based on the information acquired from the attribute detection sensor 16. For example, the attribute acquisition unit 73 holds a table in which the information detected by the attribute detection sensor 16 is previously associated with the type of sheet 12, etc. The attribute acquisition unit 73 identifies the type and name of the sheet 12 by referring to the table. The attribute acquisition unit 73 also identifies the size of the sheet 12 based on the time during which the attribute detection sensor 16 detects the sheet 12 and the conveyance speed of the sheet 12. After identifying the type, name, and size of the sheet 12, the attribute acquisition unit 73 notifies the airflow volume determination unit 75 of them.

[0054] The environmental information acquisition unit 74 acquires environmental information from the environmental sensor 35. The environmental sensor 35 has a temperature sensor 36 and a humidity sensor 37. The temperature sensor 36 detects the temperature of the environment in which the image forming apparatus 1 is installed. The humidity sensor 37 detects the humidity of the environment in which the image forming apparatus 1 is installed. Therefore, the environmental information acquisition unit 74 acquires environmental information including temperature and humidity from the environmental sensor 35. The environmental information acquisition unit 74 outputs the environmental information acquired from the environmental sensor 35 to the airflow amount determination unit 75. Note that the environmental sensor 35 may be configured to include only either the temperature sensor 36 or the humidity sensor 37. In this case, the environmental information acquisition unit 74 acquires environmental information related to temperature or humidity from the environmental sensor 35.

[0055] The airflow volume determination unit 75 determines the volume of air blown by the air blower 40 when the sheet 12 is discharged from the discharge unit 9. The airflow volume determination unit 75 determines a first airflow volume when the leading end of the sheet 12 is discharged from the discharge unit 9 and a second airflow volume when the trailing end of the sheet 12 is discharged from the discharge unit 9. The first airflow volume is determined as an airflow volume that can lift the leading end of the sheet 12 that hangs down due to discharge from the discharge unit 9 and reduce the contact angle when the leading end of the sheet 12 contacts the inclined surface 51 of the sheet loading unit 50. The second airflow volume is determined as an airflow volume that can reduce the buoyancy that lifts the trailing end of the sheet 12 after it is discharged from the discharge unit 9 and allow the trailing end of the sheet 12 to fall quickly. In other words, the second airflow volume is smaller than the first airflow volume. For example, the second airflow volume may be zero.

[0056] The position detection unit 76 detects the conveyance position of the sheet 12 based on the detection result of the sheet 12 by the sheet detection sensor 19. For example, when the sheet detection sensor 19 detects the leading edge of the sheet 12, the position detection unit 76 predicts a first timing at which the leading edge of the sheet 12 will reach the discharge rollers 30 based on the distance between the sheet detection sensor 19 and the discharge rollers 30 and the conveyance speed of the sheet 12. Furthermore, when the sheet detection sensor 19 detects the trailing edge of the sheet 12, the position detection unit 76 predicts a second timing at which the trailing edge of the sheet 12 will be discharged from the discharge rollers 30, similar to the above. Then, the position detection unit 76 instructs the fan drive unit 77 of the predicted first timing and second timing.

[0057] The fan driving unit 77 drives the fan 41 of the blower 40 to blow air onto the underside of the sheet 12 as it is discharged from the discharge unit 9. The fan driving unit 77 drives the fan 41 at a first timing instructed by the position detection unit 76. At this time, the fan driving unit 77 drives the fan 41 to blow a first amount of air. Furthermore, at a second timing instructed by the position detection unit 76, the fan driving unit 77 changes the amount of air blown by the fan 41 from the first amount of air to a second amount of air. Therefore, when the leading end of the sheet 12 is discharged from the discharge unit 9, the fan driving unit 77 blows air at the first amount of air blown onto the underside of the sheet 12. Furthermore, when the trailing end of the sheet 12 is discharged from the discharge unit 9, the fan driving unit 77 reduces the amount of air blown by the fan 41 from the first amount of air blown to the second amount of air blown. When the fan driving unit 77 changes the airflow rate of the fan 41 from the first airflow rate to the second airflow rate when the rear end of the sheet 12 is discharged from the discharge unit 9, the fan driving unit 77 stops driving the fan 41 after a predetermined time has elapsed since the airflow rate was changed. Note that the fan driving unit 77 may stop driving the fan 41 when the rear end of the sheet 12 is discharged from the discharge unit 9.

[0058] As described above, the fan driving unit 77 drives the fan 41 when the sheet 12 is discharged from the discharge unit 9, and stops driving the fan 41 when the sheet 12 is stacked on the discharge tray 10. In other words, the fan driving unit 77 does not continuously drive the fan 41 while a job is being executed, but rather drives the fan 41 intermittently each time a discharge operation for one sheet 12 is performed. Therefore, compared to when the fan 41 is continuously driven, the image forming apparatus 1 of this embodiment has the advantage of being able to reduce the power consumption by the fan 41.

[0059] 4 and 5 are diagrams illustrating the behavior of the sheet 12 being discharged from the discharge section 9. First, as shown in FIG. 4(a), when the leading edge 12a of the sheet 12 is discharged from the discharge section 9, a first airflow from the air outlet 44 hits the underside of the sheet 12. This first airflow lifts the leading edge 12a of the sheet 12. This prevents the leading edge 12a of the sheet 12 from drooping. This also prevents curling of the leading edge 12a of the sheet 12. The leading edge 12a of the sheet 12 moves downstream in the discharge direction while being lifted by the first airflow. Then, as shown in FIG. 4(b), the leading edge 12a of the sheet 12 contacts the inclined surface 51 of the sheet placement section 50 in a lifted state. At this time, the contact angle θ of the sheet 12 with the inclined surface 51 is reduced because the leading edge 12a of the sheet 12 is prevented from drooping or curling, thereby reducing the contact angle θ of the sheet 12 with the inclined surface 51. Therefore, when the leading edge 12a of the sheet 12 comes into contact with the inclined surface 51, the leading edge 12a of the sheet 12 does not get caught on the surface of the inclined surface 51. As a result, as shown in Fig. 5(a), the leading edge 12a of the sheet 12 moves smoothly downstream in the discharge direction along the inclined surface 51 in accordance with the discharge operation by the discharge roller 30.

[0060] Next, as shown in FIG. 5(b), when the trailing end 12b of the sheet 12 is discharged from the discharge section 9, the airflow rate of the fan 41 is reduced from the first airflow rate to the second airflow rate. This reduces the buoyancy that lifts the trailing end 12b of the sheet 12 discharged from the discharge section 9. As a result, the trailing end 12b of the sheet 12 quickly falls onto the sheet stacking section 50. In other words, the time required for the trailing end 12b of the sheet 12 to land is shortened, which reduces the variation in the position where the trailing end 12b of the sheet 12 falls. As a result, when multiple sheets 12 are discharged, the sheets 12 are less likely to be misaligned.

[0061] The degree of sagging and curling of the leading edge 12a of the sheet 12 discharged from the discharge section 9 varies depending on the attributes of the sheet 12. For example, recycled paper sags and curls more than regular paper. Thin paper sags and curls more than thick paper. The degree of sagging and curling of the leading edge 12a of the sheet 12 discharged from the discharge section 9 also varies depending on the job settings. For example, a double-sided printed sheet 12 passes through the fixing section 8 twice, which makes it hotter than a single-sided printed sheet 12, causing it to sag and curl more. Furthermore, the degree of sagging and curling of the leading edge 12a of the sheet 12 varies depending on environmental conditions such as temperature and humidity. For example, in a high-temperature and high-humidity environment, the degree of sagging and curling is greater than in a room-temperature and normal-humidity environment.

[0062] Therefore, when determining the first airflow rate and the second airflow rate, the airflow rate determination unit 75 refers to the control information 63 and determines the airflow rate according to the attributes of the sheet 12, the job settings, and the environmental information. FIG. 6 is a diagram showing an example of the control information 63. As shown in FIG. 6, the control information 63 is a table that specifies the airflow rate according to the sheet attributes, the job settings, and the environmental information. The control information 63 sets a value that gradually increases the first airflow rate as the degree of sagging or curling of the sheet 12 increases. The second airflow rate is set to a value that is approximately half the first airflow rate. However, the second airflow rate may be 0%. The percentages of the first airflow rate and the second airflow rate indicate the ratios to the maximum output of the fan 41.

[0063] The airflow rate determination unit 75 refers to the control information 63 based on the type, name, and size of the sheet 12 identified by the attribute acquisition unit 73. Therefore, the airflow rate determination unit 75 can determine the first airflow rate and the second airflow rate that are suitable for the attributes of the sheet 12 discharged from the discharge unit 9.

[0064] Furthermore, the airflow rate determination unit 75 refers to the control information 63 based on the job settings output from the job setting unit 71. Therefore, the airflow rate determination unit 75 can determine the first airflow rate and the second airflow rate that are suitable for the job settings. In particular, when double-sided printing is performed on the sheet 12, the airflow rate determination unit 75 can increase the first airflow rate and the second airflow rate compared to when single-sided printing is performed.

[0065] Furthermore, the airflow rate determination unit 75 refers to the control information 63 based on the environmental information output from the environmental information acquisition unit 74. Therefore, the airflow rate determination unit 75 can determine the first airflow rate and the second airflow rate that are suitable for the temperature and humidity at the time of job execution. For example, the closer the environment at the time of job execution is to a high-temperature and high-humidity environment, the more the airflow rate determination unit 75 can increase the first airflow rate and the second airflow rate.

[0066] When the leading edge 12a of the sheet 12 is discharged from the discharge section 9, the fan drive section 77 drives the fan 41 to blow air at the first airflow rate determined as described above. When the trailing edge of the sheet 12 is discharged from the discharge section 9, the fan drive section 77 drives the fan 41 to blow air at the second airflow rate determined as described above. Therefore, the control section 5 can cause the sheet 12 to be discharged at an optimal airflow rate according to the attributes of the sheet 12, the job settings, and the environmental information. As a result, the sheet 12 is properly discharged onto the discharge tray 10 under any conditions.

[0067] When the image forming apparatus 1 continuously forms images on a plurality of sheets 12, the plurality of sheets 12 are sequentially discharged onto the discharge tray 10. FIG. 7 is a diagram showing a state in which a plurality of sheets 12 are stacked on the discharge tray 10. As the number of sheets 12 stacked on the discharge tray 10 increases, the contact angle θ at which the leading edge 12a of the sheet 12 discharged from the discharge section 9 contacts the uppermost sheet 12 gradually decreases. When the contact angle θ decreases, the sheets 12 are properly stacked on the discharge tray 10 even if the first airflow rate decreases.

[0068] Therefore, it is preferable that the airflow rate determination unit 75 counts the number of sheets 12 stacked on the paper output tray 10 during job execution and corrects the first airflow rate and the second airflow rate determined as described above. In this case, the airflow rate determination unit 75 reads the correction information 64 from the storage unit 61 and determines a correction coefficient according to the number of sheets 12 stacked.

[0069] 8 is a diagram showing an example of the correction information 64. The correction information 64 is a table in which the number N of stacked sheets 12 is associated with a correction coefficient K. The correction coefficient K is, for example, a value equal to or less than 1. As shown in FIG. 8, the correction information 64 is set so that the correction coefficient K gradually decreases as the number N of stacked sheets increases.

[0070] During job execution, the airflow volume determination unit 75 adds 1 to the stack number N each time a sheet 12 is discharged onto the paper output tray 10. When the next sheet 12 is discharged from the discharge unit 9, the airflow volume determination unit 75 determines a correction coefficient K by referring to the correction information 64 based on the current stack number N. The airflow volume determination unit 75 then multiplies the first airflow volume and the second airflow volume determined by referring to the control information 63 by the correction coefficient K to determine the first airflow volume and the second airflow volume appropriate for the current stack number N. As described above, the correction coefficient K becomes smaller than 1 as the stack number N increases. Therefore, the airflow volume determination unit 75 gradually reduces the first airflow volume and the second airflow volume as the stack number N on the paper output tray 10 increases. This allows the sheets 12 to be continuously discharged appropriately onto the paper output tray 10. Furthermore, by gradually reducing the amount of air blown by the fan 41, there is also the advantage that the power consumption by the fan 41 can be reduced.

[0071] Next, an example of a processing procedure performed by the control unit 5 will be described. Figures 9 to 11 are flowcharts showing an example of a processing procedure performed by the control unit 5. This processing is performed by the CPU 60 of the control unit 5 executing the program 62.

[0072] As shown in FIG. 9, when the control unit 5 starts this process, it accepts a job setting operation by the user (step S10). When the job setting operation is accepted, the control unit 5 sets values ​​designated by the user to various setting items that are applied when the job is executed (step S11). The control unit 5 then determines whether or not an instruction to execute the job has been issued (step S12). If an instruction to execute the job has not been issued (NO in step S12), the process by the control unit 5 returns to step S10 and repeats the above-described process. If an instruction to execute the job has been issued (YES in step S12), the control unit 5 executes the process from step S13 onwards.

[0073] The control unit 5 initializes the number N of stacked sheets 12 to 0 (step S13). Then, the control unit 5 starts executing the job specified by the user (step S14). As a result, in the image forming apparatus 1, the paper feed conveying unit 6, the image forming unit 7, the fixing unit 8, and the discharge unit 9 each start operating.

[0074] The control unit 5 determines whether the sheet feeding operation of the sheet 12 has been performed by the sheet feeding and conveying unit 6 (step S15). If the sheet feeding operation has been performed (YES in step S15), the control unit 5 executes a process for determining the airflow rate (step S16).

[0075] FIG. 10 is a flowchart showing an example of a detailed processing procedure of the airflow amount determination process (step S16). When the control unit 5 starts the airflow amount determination process, it acquires detection results of the attributes of the sheet 12 from the attribute detection sensor 16 (step S20). Based on the detection results, the control unit 5 determines the attributes of the fed sheet 12 (step S21). This identifies the type, brand, size, etc. of the sheet 12. Next, the control unit 5 determines the job settings (step S22). That is, the control unit 5 determines whether the job settings are double-sided printing or single-sided printing. Next, the control unit 5 acquires environmental information from the environment sensor 35 (step S23) and determines the environmental information (step S24). This identifies the current temperature and humidity. Then, the control unit 5 references the control information 63 (step S25) and determines the first airflow amount and the second airflow amount based on the control information 63 (steps S26 and S27).

[0076] Next, the control unit 5 checks the number N of sheets 12 stacked on the paper discharge tray 10 (step S28). The control unit 5 references the correction information 64 based on the number N of sheets stacked, and determines whether or not the first airflow rate and the second airflow rate need to be corrected (step S29). For example, if the correction coefficient K corresponding to the number N of sheets stacked is 1, the control unit 5 determines that correction is not necessary. On the other hand, if the correction coefficient K corresponding to the number N of sheets stacked is not 1, the control unit 5 determines that correction is necessary.

[0077] If correction is necessary (YES in step S29), the control unit 5 reads out the correction coefficient K defined in the correction information 64 and determines the correction coefficient K (step S30). After determining the correction coefficient K, the control unit 5 multiplies the first airflow rate determined in step S26 by the correction coefficient K to correct the first airflow rate (step S31). The control unit 5 also multiplies the second airflow rate determined in step S27 by the correction coefficient K to correct the second airflow rate (step S32). The control unit 5 then determines the corrected airflow rate as the airflow rate to be applied when discharging the sheet 12. If correction is not necessary (NO in step S29), the processes of steps S30 to S32 are skipped.

[0078] Returning to the flowchart of Fig. 9, once the control unit 5 determines the first air flow rate and the second air flow rate through the air flow rate determination process, it executes the air flow control process (step S17).

[0079] FIG. 11 is a flowchart showing an example of a detailed processing procedure of the air blowing control process (step S17). When the control unit 5 starts the air blowing control process, it waits until the sheet detection sensor 19 detects the leading edge 12a of the sheet 12 (step S40). When the sheet detection sensor 19 detects the leading edge 12a of the sheet 12 (YES in step S40), the control unit 5 predicts the timing when the leading edge 12a of the sheet 12 will reach the discharge rollers 30 and be discharged from the discharge unit 9 (step S41). Thereafter, the control unit 5 waits until the leading edge 12a of the sheet 12 will reach the discharge rollers 30 (step S42). When the leading edge 12a of the sheet 12 reaches the discharge rollers 30 (YES in step S42), the control unit 5 drives the fan 41 with a first airflow rate (step S43). As a result, the leading edge 12a of the sheet 12 discharged from the discharge unit 9 is lifted by the air. This prevents the leading edge 12a of the sheet 12 from drooping or curling. In this state, the leading edge 12a of the sheet 12 comes into contact with the upper surface of the discharge tray 10, and therefore slides over the upper surface of the discharge tray 10 without being caught on the upper surface of the discharge tray 10 and moves in the discharge direction.

[0080] Next, the control unit 5 waits until the sheet detection sensor 19 detects the trailing end 12b of the sheet 12 (step S44). When the sheet detection sensor 19 detects the trailing end 12b of the sheet 12 (YES in step S44), the control unit 5 predicts the timing when the trailing end 12b of the sheet 12 will reach the discharge rollers 30 and be discharged from the discharge rollers 30 (step S45). Thereafter, the control unit 5 waits until the timing when the trailing end 12b of the sheet 12 will be discharged from the discharge rollers 30 arrives (step S46). When the timing when the trailing end 12b of the sheet 12 will be discharged from the discharge rollers 30 arrives (YES in step S46), the control unit 5 switches the airflow rate of the fan 41 from the first airflow rate to the second airflow rate (step S47). That is, the control unit 5 reduces the airflow rate of the fan 41. This reduces the buoyancy acting on the trailing end 12b of the sheet 12 being discharged from the discharge unit 9, and increases the falling speed of the trailing end 12b of the sheet 12. Therefore, the trailing ends 12b of the sheets 12 can be dropped quickly onto the discharge tray 10, and the positions of the trailing ends 12b of the sheets 12 can be aligned.

[0081] Thereafter, the control unit 5 waits until a predetermined time has elapsed (step S48). When the predetermined time has elapsed (YES in step S48), the control unit 5 stops driving the fan 41 (step S49). Note that if the second airflow rate is 0, the driving of the fan 41 is stopped in step S47. Therefore, the processes of steps S48 and S49 are not required.

[0082] Returning to the flowchart of FIG. 9 again, when the discharge operation of one sheet 12 is completed, the control unit 5 adds 1 to the number N of stacked sheets 12. Then, the control unit 5 determines whether or not the execution of the job is completed (step S19). If the execution of the job is not completed (NO in step S19), the processing by the control unit 5 returns to step S15. Then, the control unit 5 repeats the above-mentioned processing. On the other hand, if the execution of the job is completed (YES in step S19), the processing by the control unit 5 is completed.

[0083] As described above, the image forming apparatus 1 of this embodiment raises the leading edge 12a of the sheet 12 by setting the airflow rate of the air blowing unit 40 to a first airflow rate when the leading edge 12a of the sheet 12 is discharged from the discharge section 9. Then, when the trailing edge 12b of the sheet 12 is discharged from the discharge section 9, the image forming apparatus 1 changes the airflow rate of the air blowing unit 40 to a second airflow rate that is less than the first airflow rate, thereby reducing the buoyancy acting on the trailing edge 12b of the sheet 12. With the image forming apparatus 1 having this configuration, the sheets 12 discharged from the discharge section 9 are stacked on the discharge tray 10 without curling the leading edge 12a and with the trailing edge 12b aligned. Therefore, the image forming apparatus 1 can discharge the sheets 12 without curling and with the sheets 12 less likely to become misaligned.

[0084] Furthermore, the image forming apparatus 1 of this embodiment determines the first airflow rate and the second airflow rate according to the attributes of the sheets 12 discharged from the discharge section 9. Therefore, for example, even if different types of sheets 12 are discharged from the discharge section 9 during job execution, the image forming apparatus 1 can discharge the different types of sheets 12 onto the discharge tray 10 without curling them. Moreover, even if different types of sheets 12 are discharged from the discharge section 9, the image forming apparatus 1 can discharge the sheets 12 onto the discharge tray 10 in a state where the sheets 12 are less likely to become misaligned.

[0085] (Second embodiment) Next, a second embodiment of the present invention will be described. Fig. 12 is an enlarged cross-sectional view of the paper discharge tray 10 in this embodiment. In this embodiment, the air blower 40 is also disposed in a cavity inside the sheet loading section 50 provided as the paper discharge tray 10. The air blower 40 in this embodiment has two fans 41, a first fan 41a and a second fan 41b. For example, the performance of the first fan 41a and the performance of the second fan 41b are the same.

[0086] The control unit 5 of this embodiment drives the first fan 41a and the second fan 41b when the leading edge 12a of the sheet 12 is discharged from the discharge roller 30. At this time, the control unit 5 drives, for example, the first fan 41a and the second fan 41b equally. As a result, air is blown out equally from each of the first fan 41a and the second fan 41b, and a first airflow rate is blown out from the air outlet 44.

[0087] Furthermore, the control unit 5 stops driving either the first fan 41a or the second fan 41b when the trailing end 12b of the sheet 12 is discharged from the discharge roller 30. This reduces the amount of air blown out from the fan 41 by half, and air of the second amount is blown out from the air outlet 44.

[0088] In this way, the image forming apparatus 1 of this embodiment can simplify the control by the control unit 5 by providing the two fans 41, the first fan 41a and the second fan 41b, in the blower unit 40. Furthermore, since the control information 63 only needs to describe the first blowing volume, the amount of information in the control information 63 can be reduced.

[0089] The configuration and operation of this embodiment other than those described above are the same as those described in the first embodiment.

[0090] (Variation) Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications are possible.

[0091] For example, in the above embodiment, an example has been described in which the image forming apparatus 1 is configured as an MFP and has a scanning function and a printing function. However, the image forming apparatus 1 is not limited to being configured as an MFP. For example, the image forming apparatus 1 may be a printer that has only a printing function.

[0092] In the above embodiment, an example has been described in which the paper output tray 10 has the sheet placement section 50, which is an upwardly raised portion of the upper surface of the printer section 3. However, the sheet placement section 50 is not limited to an upwardly raised portion of the upper surface of the printer section 3. For example, the upper surface of the sheet placement section 50 may be formed as the upper surface of the printer section 3.

[0093] In the above embodiment, a configuration example has been described in which two sensors, the attribute detection sensor 16 and the sheet detection sensor 19, are arranged on the conveying path 15. However, the present invention is not limited to such a configuration. For example, it is also possible to give the attribute detection sensor 16 the function of the above-mentioned sheet detection sensor 19. Therefore, the above-mentioned attribute detection sensor 16 and sheet detection sensor 19 may be configured as a single sensor.

[0094] In the above embodiment, the program 62 executed by the CPU 60 is pre-stored in the storage unit 61. However, the program 62 is not limited to being pre-stored in the storage unit 61. That is, the program 62 can be traded on its own. In this case, the program 62 may be provided in a downloadable form via a network such as the Internet. The program 62 may also be provided in a form recorded on a computer-readable recording medium such as a USB memory or a CD-ROM. [Explanation of symbols]

[0095] 1. Image forming device 3 Printer section 5. Control section 9 Discharge section 10 Output tray 12 sheets 16 Attribute detection sensor 19 Sheet detection sensor 30 Ejection roller 35 Environmental Sensors 40 Blower 41 Fan 41a 1st Fan 41b Second Fan 44 Ventilation vent 50 Sheet placement area 51 Slope 62 Programs

Claims

1. a discharge unit that discharges the sheets one by one; a sheet discharge tray on which the sheets discharged from the discharge unit are stacked one by one; a blower that blows air onto the sheet discharged from the discharge unit; a control unit that controls the amount of air blown by the blower; Equipped with The control unit sets the air flow rate of the blowing unit to a first air flow rate when the leading edge of the sheet is discharged from the discharge unit, and changes the air flow rate of the blowing unit to a second air flow rate that is smaller than the first air flow rate when the trailing edge of the sheet is discharged from the discharge unit.

2. 2. The image forming apparatus according to claim 1, wherein the air blowing section has an air outlet that opens below the discharge section, and blows air upward from the air outlet.

3. 2. The image forming apparatus according to claim 1, wherein the air blowing section blows air toward a lower surface of the sheet discharged from the discharge section.

4. 2. The image forming apparatus according to claim 1, wherein the sheet ejection tray has an inclined surface whose height gradually increases in a sheet conveying direction, and the inclination angle of the inclined surface increases as the sheet approaches the ejection unit.

5. 5. The image forming apparatus according to claim 4, wherein the air blowing section is provided in a space below the inclined surface.

6. 2. The image forming apparatus according to claim 1, wherein the control unit determines the first airflow rate and the second airflow rate according to attributes of the sheet discharged from the discharge unit.

7. an attribute detection sensor provided in a conveying path along which a sheet is conveyed, the attribute detection sensor detecting an attribute of the sheet conveyed along the conveying path; Further provided with 7. The image forming apparatus according to claim 6, wherein the control unit determines the first airflow rate and the second airflow rate based on the attribute of the sheet detected by the attribute detection sensor.

8. 2. The image forming apparatus according to claim 1, wherein the control unit determines the first airflow rate and the second airflow rate in accordance with a job setting.

9. 9. The image forming apparatus according to claim 8, wherein the job settings include settings for double-sided printing or single-sided printing for sheets.

10. an environmental sensor for obtaining environmental information related to temperature or humidity; Further provided with 2. The image forming apparatus according to claim 1, wherein the control unit determines the first airflow rate and the second airflow rate in accordance with the environmental information.

11. 2. The image forming apparatus according to claim 1, wherein the control unit counts the number of sheets stacked on the paper discharge tray, and determines the first airflow rate and the second airflow rate according to the number of sheets stacked.

12. a sheet detection sensor provided in a conveyance path along which the sheet is conveyed and configured to detect the sheet; Further provided with 2. The image forming apparatus according to claim 1, wherein the control unit predicts the timing at which the leading edge or trailing edge of the sheet will be discharged from the discharge unit based on the detection result of the sheet by the sheet detection sensor.

13. 2. The image forming apparatus according to claim 1, wherein the control unit stops driving the air blowing unit when the trailing edge of the sheet is discharged from the discharge unit.

14. The blower unit has a first fan and a second fan, 2. The image forming apparatus according to claim 1, wherein the control unit drives both the first fan and the second fan when the leading edge of the sheet is discharged from the discharge unit, and stops driving one of the first fan and the second fan when the trailing edge of the sheet is discharged from the discharge unit.

15. 2. The image forming apparatus according to claim 1, wherein the control unit stops driving the air blowing unit after a predetermined time has elapsed since changing the air blowing volume of the air blowing unit to a second air blowing volume that is less than the first air blowing volume.

16. a discharge unit that discharges the sheets one by one; a sheet discharge tray on which the sheets discharged from the discharge unit are stacked one by one; a blower that blows air onto the sheet discharged from the discharge unit; A control method for an image forming apparatus comprising: A control method characterized by setting the air blowing volume by the air blowing section to a first air blowing volume when the leading end of the sheet is discharged from the discharge section, and changing the air blowing volume by the air blowing section to a second air blowing volume that is smaller than the first air blowing volume when the trailing end of the sheet is discharged from the discharge section.

17. a discharge unit that discharges the sheets one by one; a sheet discharge tray on which the sheets discharged from the discharge unit are stacked one by one; a blower that blows air onto the sheet discharged from the discharge unit; A program executed in an image forming apparatus comprising: a first step of setting the airflow rate of the air blowing unit to a first airflow rate when the leading edge of the sheet is discharged from the discharge unit; a second step of changing the airflow rate of the air blowing unit to a second airflow rate that is less than the first airflow rate when the trailing end of the sheet is discharged from the discharge unit; A program characterized by executing the following.

Images