JP2024095360A - Image forming device - Google Patents

Abstract

[Problem] To provide an image forming device that can suppress adhesion of foreign matter from the sheet to the cutter even when the sheet is cut with the cutter, and can suppress deterioration of cutter characteristics such as the cutting performance and durability of the cutter. [Solution] An image forming device (1) includes an image forming unit (4), a discharge roller (40A), a cutter (100), and a control unit (C). Before performing a cutting process, the control unit (C) executes a determination process to determine whether or not an image will be formed at the cutting position of the sheet (S), and if it determines in the determination process that an image will be formed at the cutting position of the sheet (S), it executes a suppression process to suppress adhesion of foreign matter from the sheet (S) to the cutter (100) during the cutting process. [Selected Figure] Figure 1

Description

This disclosure relates to an image forming apparatus.

As an image forming apparatus such as an electrophotographic printer, there is known an apparatus equipped with a fixing unit that heats the sheet on which the image is formed to fix the developer image. In addition, as an example of a conventional image forming apparatus, the following Patent Document 1 proposes providing an ejection section provided above the fixing section and from which the paper is ejected, and a cutter provided between the fixing section and the ejection section to cut the paper.

JP 2002-362823 A

However, in the above conventional technology, depending on the position where the image on the sheet is formed, there is a possibility that foreign matter such as toner or ink from the image on the sheet may adhere to the cutter. As a result, in the above conventional technology, there is a possibility that cutter characteristics such as the cutter's sheet cutting performance and cutter durability may be reduced.

The present disclosure aims to provide an image forming apparatus that can prevent foreign matter from adhering to the cutter from the sheet even when the sheet is cut with the cutter, and can prevent a decrease in cutter characteristics such as the cutting performance and durability of the cutter.

In order to solve the above problem, the image forming apparatus of the present disclosure includes an image forming unit that forms an image on a sheet, a discharge roller that is disposed downstream of the image forming unit in the sheet conveying direction and that discharges the sheet out of the image forming apparatus, a cutter that is disposed at a cutter position downstream of the image forming unit in the conveying direction and that cuts the sheet, and a control unit, and the control unit rotates the discharge roller to convey the sheet that has passed through the image forming unit, stops the discharge roller when the cutting position of the sheet reaches the cutter position, and then performs a cutting process in which the sheet is cut by the cutter, a determination process that determines whether an image is formed at the cutting position of the sheet before performing the cutting process, and a suppression process that suppresses adhesion of foreign matter from the sheet to the cutter during the cutting process if the determination process determines that an image is formed at the cutting position of the sheet.

According to the above configuration, even if an image is formed at the cutting position of the sheet, it is possible to prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and to prevent a decrease in the cutter characteristics, such as the cutting performance and durability of the cutter.

The image forming device of the present disclosure may further include a receiving unit that receives a print job, and in the determination process, the control unit may determine whether or not an image is to be formed at the cutting position of the sheet based on print data to be printed on the sheet by the image forming unit, which is included in the print job received by the receiving unit.

According to the above configuration, the control unit executes the judgment process based on the print data included in the print job, so the judgment process can be performed with high accuracy. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

The image forming device of the present disclosure may further include a detection sensor that detects an image formed on a sheet, and the control unit may determine in the determination process whether or not an image is to be formed at the cutting position of the sheet based on the detection result of the detection sensor.

According to the above configuration, the control unit executes the judgment process based on the detection result of the detection sensor, so that the judgment process can be performed with high accuracy. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

The image forming device of the present disclosure may further include an operation reception unit, and in the determination process, the control unit may determine whether or not an image is formed at the cutting position of the sheet based on the cutting position of the sheet received by the operation reception unit.

According to the above configuration, the control unit executes the judgment process based on the cutting position of the sheet received by the operation reception unit, so the judgment process can be performed with high accuracy. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

The image forming apparatus of the present disclosure further includes a fixing section that is disposed downstream of the image forming section in the conveying direction and has a heating rotator, a heater that heats the heating rotator, and a pressure rotator that forms a nip portion between the heating rotator and the heating rotator, and fixes an image on a sheet, and a main motor that transmits a driving force to at least the heating rotator or the pressure rotator, the discharge roller is disposed downstream of the fixing section in the conveying direction, the cutter position is downstream of the fixing section in the conveying direction, the control section controls the heater so that the target temperature of the heating rotator becomes a printing temperature that fixes an image on the sheet, and is capable of executing a motor control process that controls the main motor to rotate the heating rotator or the pressure rotator to convey the sheet, and in the cutting process, the discharge roller is rotated to convey the sheet that has passed through the nip portion, and when the cutting position of the sheet reaches the cutter position, the discharge roller is stopped, and then the sheet is cut by the cutter.

According to the above configuration, even if an image is formed at the cutting position of the sheet, it is possible to prevent foreign matter from the sheet from adhering to the cutter during the cutting process, and to prevent a deterioration in the cutter characteristics.

In the image forming device of the present disclosure, the control unit may control the heater as the suppression process by setting the target temperature of the heating rotor to a first temperature higher than the printing temperature depending on the timing when the cutting position of the sheet passes through the nip portion.

According to the above configuration, the control unit can increase the fixing strength by locally heating the cutting position of the sheet during the suppression process. This makes it possible to more reliably suppress the adhesion of foreign matter from the sheet to the cutter during the cutting process, and more reliably suppress the deterioration of the cutter characteristics.

In the image forming device of the present disclosure, the control unit may control the heater with the target temperature of the heating rotor as the first temperature within a predetermined range after the leading edge of the sheet passes through the nip portion and before the trailing edge of the sheet passes through the nip portion.

According to the above configuration, the control unit can set the range in which the cutting position of the sheet is locally heated to a predetermined range, which makes it possible to prevent curling of the sheet compared to heating the entire sheet.

In the image forming device of the present disclosure, the control unit may control the heater with the target temperature of the heating rotor as the printing temperature after the cutting position of the sheet passes through the nip portion.

According to the above configuration, the control unit controls the heater so that the target temperature of the heating rotor is set to a printing temperature that is lower than the first temperature, thereby preventing the heating rotor and the pressure rotor from locally increasing in temperature.

In the image forming device of the present disclosure, the image forming unit has a photosensitive drum, is arranged upstream of the photosensitive drum in the transport direction, and further includes a registration roller that is the transport roller closest to the photosensitive drum among a plurality of transport rollers that transport a sheet, and is arranged between the photosensitive drum and the registration roller in the transport direction and is capable of detecting the passage of a sheet, and the control unit may control the heater by setting the target temperature of the heating rotor as the first temperature based on the time when the sheet sensor detects the sheet.

According to the above configuration, the control unit sets the target temperature of the heating rotor to the first temperature based on the detection result of the sheet sensor, so that the suppression process can more appropriately locally heat the cutting position of the sheet.

The image forming device of the present disclosure may further include a re-conveying path for re-conveying the sheet that has passed through the fixing unit toward the image forming unit, and the control unit may transport the sheet that has passed through the fixing unit to the re-conveying path as the suppression process.

According to the above configuration, the control unit passes the sheet through the re-conveyance path during the suppression process, so that the sheet passes through the fixing unit twice, thereby increasing the fixing strength of the sheet. This makes it possible to more reliably suppress adhesion of foreign matter from the sheet to the cutter during the cutting process, and more reliably suppress deterioration of the cutter characteristics.

In the image forming device of the present disclosure, the control unit may perform the suppression process by stopping the rotation of the discharge roller for a predetermined time during the period from when the trailing edge of the sheet passes through the nip portion until the cutting position of the sheet reaches the cutter position, and then rotating the discharge roller again.

According to the above configuration, the control unit temporarily stops the transport of the sheet that has passed through the nip portion, so that the sheet can be cooled reliably. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

In the image forming device of the present disclosure, the control unit may, as the suppression process, set the length of the period from when the cutting position of the sheet reaches the cutter position, to when the discharge roller is stopped, and to when the cutting process is executed to be longer when an image is formed at the cutting position of the sheet than when an image is not formed at the cutting position of the sheet.

According to the above configuration, the control unit temporarily waits for the sheet that has reached the cutter position before performing the cutting process on the sheet, and the sheet can be cooled reliably. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

In the image forming device disclosed herein, the control unit may slow the sheet conveying speed when performing the suppression process compared to when the suppression process is not performed.

According to the above configuration, when the suppression process is executed, the control unit slows down the sheet conveying speed compared to when the suppression process is not executed, so that the sheet can be cooled reliably while being conveyed. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

The image forming apparatus of the present disclosure may further include a fan that exhausts air to the outside, and the control unit may increase the drive speed of the fan after the cutting position of the sheet passes through the nip portion as the suppression process.

According to the above configuration, the control unit increases the drive speed of the fan after the cutting position of the sheet passes through the nip portion, so that the sheet can be cooled reliably. This makes it possible to more reliably prevent foreign matter from adhering to the cutter from the sheet during the cutting process, and more reliably prevents deterioration of the cutter characteristics.

The image forming device of the present disclosure may further include a discharge motor that transmits a driving force to the discharge roller.

With the above configuration, the control unit can independently control the discharge rollers by controlling the discharge motor, allowing the discharge rollers to operate more appropriately.

In the image forming device of the present disclosure, the image forming unit has a photosensitive drum, a developing roller that supplies toner to the photosensitive drum, and a transfer unit that transfers the toner supplied onto the photosensitive drum to a sheet, and the photosensitive drum and the developing roller may be rotated by a driving force from the main motor.

With the above configuration, the control unit can control the photosensitive drum and the developing roller by controlling the main motor, allowing the image forming unit to operate more appropriately.

According to one aspect of the present disclosure, it is possible to provide an image forming apparatus that can prevent foreign matter from adhering to the cutter from the sheet even when the sheet is cut with a cutter, and can prevent deterioration of the cutter characteristics, such as the cutting performance and durability of the cutter.

1 is a diagram illustrating a schematic configuration of an image forming apparatus according to a first embodiment of the present disclosure. FIG. 2 is a block diagram showing an electrical configuration of the image forming apparatus shown in FIG. 1 . 4 is a flowchart showing an example of a basic operation of the image forming apparatus shown in FIG. 1 . 4 is a flowchart showing an example of the operation of the print cutting process shown in FIG. 3 . 4 is a timing chart showing a specific example of the relationship between the drive timing and the fixing temperature of the fixing unit in the image forming apparatus shown in FIG. 1 . 2A to 2C are diagrams illustrating a specific example of a sheet cutting process performed by the cutter illustrated in FIG. 1 . 10 is a flowchart illustrating an example of an operation of a print cutting process in an image forming apparatus according to a first modified example of the present disclosure. 10 is a flowchart illustrating an example of an operation of a print cutting process in an image forming apparatus according to a second modified example of the present disclosure. FIG. 11 is a diagram illustrating a schematic configuration of an image forming apparatus according to a second embodiment of the present disclosure. FIG. 11 is a diagram illustrating a schematic configuration of an image forming apparatus according to a third embodiment of the present disclosure.

[Embodiment 1]
A first embodiment of the present disclosure will be described below with reference to Fig. 1. In the following description, a laser printer that forms an image on a sheet S using toner will be described as an example of an image forming apparatus 1.

[Overall configuration of image forming apparatus 1]
Fig. 1 is a diagram for explaining a schematic configuration of an image forming apparatus 1 according to a first embodiment of the present disclosure. In the following explanation, the up-down direction is defined with the installation surface side as the bottom, based on the state in which the image forming apparatus 1 is installed and ready for use, as shown in Fig. 1. Also, the front-rear direction is defined with the side where the discharge tray TR is provided as the front.

In the following description, the image forming device 1 is exemplified as a monochrome printer that performs image formation processing for monochrome images. However, the present disclosure is not limited to this, and may be, for example, a color printer that has an intermediate transfer belt and performs image formation processing for full-color images. The present disclosure may also be an inkjet printer that performs image formation processing by, for example, ejecting ink to print data specified by a print job. The present disclosure may also be an MFP (Multi-Function Printer) that also has functions other than the image forming function, i.e., the print function, such as a scanner function, copy function, or facsimile function.

In the following description, an example will be given in which the cutter 100 completely separates the sheet S into a first sheet and a second sheet that are arranged back and forth in the conveying direction. However, the present disclosure is not limited in any way as long as it has a blade for cutting the sheet S. Specifically, the present disclosure may perform a cutting process in which the blade of the cutter 100 is applied to cut the sheet S. The present disclosure may also perform a folding process in which a crease is made using the blade of the cutter 100 to cut the sheet S. The present disclosure may also perform a perforation process in which a perforation is made using the blade of the cutter 100 to cut the sheet S.

As shown in FIG. 1, the image forming device 1 includes a housing 10, a feed unit 3, an image forming unit 4, a fixing unit 45, and a discharge tray TR. The image forming device 1 also includes a cutter 100, a control unit C, and a main motor M0.

The housing 10 constitutes the outer container of the image forming device 1 and contains the main components of the image forming device 1, such as the feed unit 3, the image forming unit 4, the fixing unit 45, the cutter 100, and the control unit C.

[Configuration of Feeding Section 3]
The feeding unit 3 supplies sheets S. The feeding unit 3 includes a feeding tray 31, a pickup roller 32, a pressure plate 33, a separation roller 34, a feeding roller 35, and a registration roller 36. The feeding tray 31 is a box-shaped member with an open top, and stores a predetermined amount of sheets S. The sheets S are not limited to paper media such as printing paper, and may also be resin media made of plastic, such as overhead projector sheets.

The pickup roller 32 feeds out the sheets S stored in the feed tray 31. That is, when the sheets S are fed out, the sheets S stored in the feed tray 31 are brought to the pickup roller 32 by the pressure plate 33, and are fed to the separation roller 34 as the pickup roller 32 rotates. The separation roller 34 separates the sheets S fed out by the pickup roller 32 one by one. The feed roller 35 transports the sheets S toward the registration roller 36.

The registration roller 36 aligns the leading edge of the sheet S and then transports the sheet S toward the image forming unit 4. Among the multiple transport rollers that transport the sheet S, the registration roller 36 is the transport roller closest to the photosensitive drum 46 described below. The image forming device 1 is also provided with multiple sheet sensors that can detect the passage of the sheet S, and the post-registration sensor K3 described below is an example of a sheet sensor that is disposed between the photosensitive drum 46 and the registration roller 36.

[Configuration of image forming unit 4]
The image forming unit 4 executes a process for forming an image on the sheet S sent out by the feeding unit 3. Specifically, the image forming unit 4 has an exposure unit 41, a charger 43, and a photosensitive drum 46. The image forming unit 4 also has a developing unit 44 that supplies toner onto the photosensitive drum 46, and a transfer unit 42 that has a transfer roller 42R (FIG. 2) that transfers the toner supplied onto the photosensitive drum 46 onto the sheet S.

The exposure device 41 exposes the photosensitive drum 46 by irradiating the photosensitive drum 46 with a predetermined light beam B, shown by a dashed line in FIG. 1, from a laser generating unit 41A (FIG. 2). Specifically, the exposure device 41 includes a laser generating unit 41A, a polygon mirror 41G, a scanning lens 41L, a polygon motor 41M, and a reflecting mirror 41R.

The polygon mirror 41G is a rotating polygonal mirror with six reflecting surfaces on the side of a regular hexagonal prism. The polygon mirror 41G is used to deflect the light beam B emitted by the laser generating unit 41A in a direction toward the photosensitive drum 46. The polygon motor 41M is a motor different from the main motor M0. The polygon motor 41M is also connected to the control unit C, and drives the polygon mirror 41G to rotate independently of the main motor M0 based on operation instructions from the control unit C.

The exposure device 41 deflects the light beam B using a polygon mirror 41G, and emits the light beam B from the polygon mirror 41G to the surface of the photosensitive drum 46 via a scanning lens 41L and a reflecting mirror 41R. The exposure device 41 scans the surface of the photosensitive drum 46 with the light beam B to expose the photosensitive drum 46. As a result, an electrostatic latent image is formed on the surface of the photosensitive drum 46. The polygon motor 41M is, for example, a brushless DC motor.

The charger 43 includes, for example, a scorotron type charger having a charging wire and a grid section (not shown). In this charger 43, a charging voltage is applied to the charging wire by a high voltage generating circuit (not shown), and a grid voltage is applied to the grid section, causing a corona discharge, and the surface of the photosensitive drum 46 is uniformly charged. Note that, for example, instead of a scorotron type charger, the charger 43 may include a charging roller.

The developing unit 44 includes a developing roller 44R for supplying toner as a developer onto the photosensitive drum 46, and a toner storage unit 44A that stores the toner. The developing unit 44 is also configured such that the developing roller 44R and the toner storage unit 44A are integrated into a toner cartridge.

The transfer unit 42 includes a transfer roller 42R (FIG. 2) that sandwiches the sheet S between the transfer roller 42R and the photosensitive drum 46, and transfers the toner image from the photosensitive drum 46 to the sheet S. Note that the transfer unit 42 may include a transfer belt instead of the transfer roller 42R, for example.

The photosensitive drum 46 and the charger 43 are integrally configured as a drum cartridge 47. When a front cover (not shown), which is configured to be openable and closable, is open relative to the housing 10, the drum cartridge 47 can be attached and detached from the front cover side. When the front cover is open, the developing unit 44 as a toner cartridge or the drum cartridge 47 can be attached and detached.

The above description concerns a case where a process cartridge is used in which the developing unit 44 as a toner cartridge and the drum cartridge 47 are separable from each other. However, the present disclosure is not limited to this, and it is also possible to use, for example, an integrated process cartridge in which the toner cartridge and the drum cartridge are inseparable.

In the image forming unit 4, the surface of the photosensitive drum 46 is uniformly charged by the charger 43, and then an electrostatic latent image based on the print data from the control unit C is formed on the surface of the photosensitive drum 46 by the light beam B from the exposure unit 41. In addition, the developing roller 44R supplies toner from inside the developing unit 44 to the surface of the photosensitive drum 46 on which the electrostatic latent image has been formed. This makes the electrostatic latent image visible, and a toner image is formed on the surface of the photosensitive drum 46. Thereafter, the sheet S fed from the feeding unit 3 is transported to a transfer position between the photosensitive drum 46 and the transfer unit 42, and the toner image formed on the surface of the photosensitive drum 46 is transferred onto the sheet S.

[Configuration of Fixing Unit 45]
The sheet S onto which the toner image has been transferred is transported to the fixing section 45 by the photosensitive drum 46 and the transfer section 42. The fixing section 45 fixes the image, which is the toner image formed on the sheet S. Specifically, the fixing section 45 thermally fixes the toner image on the sheet S transported from the photosensitive drum 46 and the transfer section 42. The sheet S onto which the toner image has been thermally fixed is discharged onto the discharge tray TR by the intermediate discharge rollers 37 and the first discharge rollers 38. The discharge tray TR is a storage section for the sheet S provided on the exposed portion of the top surface of the housing 10, as shown by the solid line in FIG. 1.

The fixing unit 45 includes, for example, a heating roller 45HR that contacts the sheet S on which the toner image is formed and heats the sheet S, a pressure roller 45PR that is pressed toward the heating roller 45HR by a pressing unit (not shown), and a heater 45H that heats the heating roller 45HR. In the fixing unit 45, a nip portion N is formed between the heating roller 45HR and the pressure roller 45PR, and the toner image is fixed to the sheet S with a predetermined pressure being applied at the nip portion N. The heating roller 45HR and the pressure roller 45PR are examples of a heating rotator and a pressure rotator, respectively.

Inside the heating roller 45HR, for example, two heaters 45H are provided. The heaters 45H are, for example, constructed using halogen lamps. The heaters 45H emit light and generate heat when energized, and heat the heating roller 45HR from the inside by radiating heat. Furthermore, inside the fixing unit 45, there is provided a temperature sensor 45S (Figure 2) that detects the temperature of the heating roller 45HR, and the temperature sensor 45S outputs a signal corresponding to the detected temperature to the control unit C.

Specifically, the control unit C controls a current supply circuit (not shown) to the heater 45H. This allows the control unit C to control the heating of the heating roller 45HR from the heater 45H. The control unit C also controls the rotational drive of the pressure roller 45PR by controlling the main motor M0. Then, in the fixing unit 45, the sheet S to which the toner image has been transferred is transported to the nip portion N between the heating roller 45HR and the pressure roller 45PR, whereby the toner image is thermally fixed onto the sheet S. In other words, the control unit C is capable of executing a motor control process that controls the main motor M0 to rotate the pressure roller 45PR and transport the sheet while executing temperature control of the heater 45H.

In the above description, the driving force from the main motor M0 is transmitted to the pressure roller 45PR to rotate and drive the pressure roller 45PR, but this embodiment is not limited to this. It is sufficient that the main motor M0 transmits driving force to at least the heating roller 45HR or the pressure roller 45PR in accordance with instructions from the control unit C to rotate and drive the pressure roller 45PR.

Although the fixing unit 45 having two rollers, the heating roller 45HR and the pressure roller 45PR, has been described, the fixing unit 45 of the present disclosure is not limited to this. For example, instead of the heating roller 45HR, an endless belt that sandwiches the sheet S with the pressure roller 45PR may be provided. In this case, the belt may be configured to rotate around a nip plate that receives radiant heat from the heater 45H. Also, instead of a halogen lamp, the heater 45H may have a substrate and a resistance heating element provided on the substrate, and a heating unit equipped with a heater that contacts the inner peripheral surface of the belt may be used in the fixing unit. Also, for example, a pressure pad type fixing unit equipped with an endless belt that sandwiches the sheet S with the heating roller 45HR and a nip forming member having a pressure pad that presses the endless belt against the heating roller 45HR side may be used.

[Configuration of the transport path]
1, the image forming apparatus 1 includes a transport path which is a space for transporting the sheet S along a predetermined transport direction. Specifically, the image forming apparatus 1 includes a supply transport path H0 for transporting the sheet S from the feeding unit 3 toward the image forming unit 4, and a first transport path H1 for transporting the sheet S that has passed through the fixing unit 45 toward the discharge tray TR. The image forming apparatus 1 also includes a third transport path H3 for transporting the sheet S that has passed through the fixing unit 45 toward a cutter 100 disposed at a predetermined cutter position. In other words, the cutter 100 is disposed in the third transport path H3 at a cutter position downstream of the image forming unit 4 in the transport direction.

More specifically, in the supply conveying path H0, the location where the pickup roller 32 is installed is the start point of the conveying of the sheet S, and the location where the post-registration sensor K3 described below is installed is the end point of the conveying of the sheet S. In addition, in the supply conveying path H0, for example, the pickup roller 32, separation roller 34, feed roller 35, and registration roller 36 are installed as conveying rollers for conveying the sheet S. In addition, in the supply conveying path H0, a pre-registration sensor K2 and a post-registration sensor K3 are provided.

The pre-registration sensor K2 and the post-registration sensor K3 detect the leading edge and trailing edge of the sheet S, respectively. The pre-registration sensor K2 and the post-registration sensor K3 can each be a sensor having an actuator that swings when the sheet S comes into contact with it, an optical sensor, or the like.

In addition, the pre-registration sensor K2 and the post-registration sensor K3 output the detection results to the control unit C. Specifically, the pre-registration sensor K2 outputs an ON signal to the control unit C from the time when the leading edge of the sheet S reaches the position of the pre-registration sensor K2 until the trailing edge of the sheet S passes the position of the pre-registration sensor K2, and outputs an OFF signal otherwise. Similarly, the post-registration sensor K3 outputs an ON signal to the control unit C from the time when the leading edge of the sheet S reaches the position of the post-registration sensor K3 until the trailing edge of the sheet S passes the position of the post-registration sensor K3, and outputs an OFF signal otherwise.

In the first transport path H1, the end point of the supply transport path H0 is the start point of the transport of the sheet S, and the connection point G2 with the discharge tray TR is the end point of the transport of the sheet S. In other words, the first transport path H1 is a transport path between the installation location of the post-registration sensor K3 and the connection point G2, which is the end of the discharge tray TR that is exposed on the top side of the housing 10 and allows the user to collect the sheet S. In addition, the first transport path H1 is provided with, for example, an intermediate discharge roller 37 and a first discharge roller 38 as transport rollers for transporting the sheet S. The intermediate discharge roller 37 is configured to rotate, for example, by a driving force from the main motor M0. In addition, the first discharge roller 38 is configured to rotate, for example, by a driving force from the discharge motor M3.

In the first conveying path H1, a detection sensor K5 is provided between the photosensitive drum 46 and the fixing unit 45. The detection sensor K5 is configured, for example, using an optical sensor. The detection sensor K5 is configured to detect the presence or absence of an image formed on the sheet S between the photosensitive drum 46 and the fixing unit 45. Specifically, the detection sensor K5 is a known optical sensor equipped with a light-emitting element and a light-receiving element, and is configured to irradiate light from the light-emitting element to the sheet S and detect the amount of light reflected from the sheet S with the light-receiving element. The detection sensor K5 then outputs the detection result of the light amount of the specular reflection component and the diffuse reflection component of the reflected light to the control unit C. The control unit C is configured to detect the concentration of the toner on the sheet S based on the light amount of the specular reflection component and the diffuse reflection component, thereby determining whether an image is formed at an arbitrary position on the sheet S, for example, at a cutting position. The detection sensor K5 may be configured to detect the light amount of light transmitted through the sheet S with the light-receiving element.

In the first transport path H1, a paper discharge sensor K4 is provided between the fixing unit 45 and the intermediate discharge rollers 37. The paper discharge sensor K4 is configured using a sensor having an actuator that oscillates when the sheet S comes into contact with it, an optical sensor, or the like. The paper discharge sensor K4 is configured to detect the presence or absence of the sheet S between the fixing unit 45 and the intermediate discharge rollers 37. The paper discharge sensor K4 is configured to output the presence or absence of the sheet S to the control unit C.

Specifically, the discharge sensor K4 outputs an OFF signal to the control unit C before the sheet S passes through the discharge sensor K4, and outputs an ON signal while the sheet S passes through the nip portion N and passes through the discharge sensor K4. In other words, when the leading edge of the sheet S in the transport direction enters the discharge sensor K4, the discharge sensor K4 outputs an ON signal, and then when the trailing edge of the sheet S leaves the discharge sensor K4, the discharge sensor K4 outputs an OFF signal.

The transport start point of the sheet S on the third transport path H3 is the junction G1 with the first transport path H1. The junction G1 is located upstream of the first discharge roller 38 in the transport direction.

On the other hand, the transport end point of the sheet S on the third transport path H3 is a connection point G2 that is connected to the discharge tray TR. The connection point G2 is a different point from the junction point G1. The connection point G2 is downstream of the first discharge roller 38 in the transport direction.

As shown in FIG. 1, the third transport path H3 is a transport path different from the first transport path H1. The third transport path H3 is disposed above the first transport path H1.

In addition, a flapper FP is provided near the junction G1 to distribute the sheet S to the first transport path H1 or the third transport path H3. When the sheet S is not to be cut by the cutter 100, the control unit C moves the flapper FP to the first position to transport the sheet S to the first transport path H1 toward the discharge tray TR. When the sheet S is to be cut, the control unit C moves the flapper FP to the second position to transport the sheet S to the third transport path H3 toward the cutter 100.

In addition, in the third transport path H3, as transport rollers for transporting the sheet S, for example, a second discharge roller 40A and a third discharge roller 40B are sequentially provided so as to sandwich the cutter 100 along the transport direction in the third transport path H3. The second discharge roller 40A and the third discharge roller 40B are configured to operate by the driving force from the discharge motor M3, similar to the first discharge roller 38, for example. In other words, the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B are disposed downstream of the image forming unit 4 in the transport direction of the sheet S, and are an example of discharge rollers for discharging the sheet S outside the image forming device 1.

[Configuration of cutter 100]
The cutter 100 is a well-known cutter mechanism capable of cutting the sheet S. The cutter 100 has, for example, a blade 103A, a fixed blade 103B, a cutter carriage, and a cutting motor M1. Note that the cutter 100 may have a pair of upper and lower blades.

The blade 103A is, for example, a rotatable round blade, and is held by a cutter carriage. The fixed blade 103B is fixed to a frame that is provided to extend in the left-right direction within the housing 10. The cutter carriage is configured to be able to move back and forth in the width direction of the sheet S along a rail that is provided to extend in the left-right direction on the housing 10 by the driving force of the cutting motor M1.

When the sheet S is at the cutter position of the cutter 100, the cutter carriage moves along the width direction of the sheet S, so that the sheet S is sandwiched between the blade 103A and the fixed blade 103B and cut.

In addition to the above description, for example, a so-called guillotine type blade may be used that is provided along the width direction of the sheet S and that cuts the sheet S by moving up and down relative to the sheet S, or a movable blade that moves in the width direction of the sheet S together with the blade 103A when cutting the sheet S may be used instead of the fixed blade 103B. Also, a configuration in which the sheet S is sandwiched between two blades like scissors and cut may be used.

[Electrical configuration of image forming apparatus 1]
Next, the electrical configuration of the image forming apparatus 1 will be described with reference to Fig. 2. Fig. 2 is a block diagram showing the electrical configuration of the image forming apparatus 1 shown in Fig. 1. As shown in Fig. 2, the image forming apparatus 1 further includes an ASIC (Application Specific Integrated Circuit) 105, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a NVRAM (Non-Volatile Random Access Memory) 104, an operation panel 120, and a communication I/F (communication interface) 130.

The ASIC 105 is equipped with a CPU (Central Processing Unit) 101. The CPU 101 is an example of a control unit C, and performs overall control over each unit of the image forming device 1. The ASIC 105 is electrically connected to the ROM 102, the RAM 103, the NVRAM 104, the cutting motor M1, the electromagnetic clutch 107, the main motor M0, and the discharge motor M3. The ASIC 105 is also electrically connected to the pre-registration sensor K2, the post-registration sensor K3, the paper discharge sensor K4, the operation panel 120, the communication I/F 130, the image forming unit 4, the exposure unit 41, and the fixing unit 45.

The ROM 102 stores various control programs and various settings for controlling the image forming device 1. Specifically, the ROM 102 stores information on the fixing temperature of the heating roller 45HR when fixing an image onto the sheet S. The fixing temperature includes a predetermined printing temperature and a first temperature that is higher than the printing temperature, as described below.

In addition, ROM 102 stores information on the standby temperatures of heating roller 45HR and pressure roller 45PR when waiting for sheet S to be transported. In addition, ROM 102 stores information on the temperature at which heating roller 45HR can feed sheet S when transporting sheet S from feed tray 31.

RAM 103 is used as a working area from which various control programs are read, and as a storage area for temporarily storing image data included in a print job. CPU 101 controls each part of image forming device 1 while storing the processing results in RAM 103 or NVRAM 104 according to the control programs read from ROM 102 and the signals output from various sensors.

The cutting motor M1 is, for example, a brushless DC motor, and is a motor different from the main motor M0. The cutting motor M1 moves the cutter carriage independently of the main motor M0 based on an operation instruction from the CPU 101, thereby moving the blade 103A in the width direction of the sheet S to cut the sheet S.

The main motor M0 is, for example, a brushless DC motor. The main motor M0 also transmits driving force to the pickup roller 32, separation roller 34, feed roller 35, registration roller 36, pressure roller 45PR, and drum cartridge 47. When the CPU 101 drives the main motor M0 in the forward direction, the driving force is transmitted from the main motor M0 to the pressure roller 45PR, photosensitive drum 46, development roller 44R, pickup roller 32, separation roller 34, feed roller 35, and registration roller 36.

The pressure roller 45PR, photosensitive drum 46, developing roller 44R, pickup roller 32, separation roller 34, feed roller 35, and registration roller 36 rotate in a direction that transports the sheet S in the transport direction. The main motor M0 transmits driving force to the photosensitive drum 46, developing roller 44R, etc., so that the photosensitive drum 46, developing roller 44R, etc. can be driven collectively by the main motor M0.

On the other hand, even if the CPU 101 drives the main motor M0 in the reverse direction, the driving force is not transmitted to the pressure roller 45PR, the drum cartridge 47, the pickup roller 32, the separation roller 34, the feed roller 35, and the registration roller 36.

The electromagnetic clutch 107 is controlled by the CPU 101. The electromagnetic clutch 107 can be switched between a transmission state in which the driving force is transmitted from the main motor M0 to the pickup roller 32 and a non-transmission state in which the driving force is not transmitted from the main motor M0 to the pickup roller 32.

Specifically, CPU 101 turns on electromagnetic clutch 107 to bring the main motor M0 into a transmission state in which the driving force is transmitted to pickup roller 32. On the other hand, CPU 101 turns off electromagnetic clutch 107 to bring the main motor M0 into a non-transmission state in which the driving force is not transmitted to pickup roller 32. When image forming apparatus 1 is started, CPU 101 sets electromagnetic clutch 107 to off.

The discharge motor M3 is, for example, a brushless DC motor. The discharge motor M3 transmits driving force to the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B. The CPU 101 drives the discharge motor M3 in the forward direction to transmit driving force to the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B. The first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B then rotate in a direction to transport the sheet S in the transport direction.

The operation panel 120 is an example of an operation reception section, and has, for example, a touch panel in which a touch pad and a display are integrally formed, and a key button section. The operation panel 120 receives user operations and outputs the received information to the CPU 101. For example, the user can set whether or not to cut the sheet S by operating the operation panel 120. Furthermore, the CPU 101 is configured to be capable of executing a determination process to determine whether or not an image is to be formed at the cutting position of the sheet S, based on the cutting position of the sheet S received by the operation panel 120.

The communication I/F 130 is connected to a network such as a LAN, and enables connection to an external device such as a PC incorporating a driver for the image forming device 1. The CPU 101 is capable of receiving a print job via the communication I/F 130, and is an example of a receiving unit. The print job includes various information required to form an image on the sheet S, such as image data for forming an image, i.e., print data, the size and type of the sheet S used for image formation, etc. Furthermore, the CPU 101 is configured to be capable of executing a determination process to determine whether or not an image is formed at the cutting position of the sheet S, based on the print data to be printed on the sheet S by the image forming unit 4, which is included in the print job received by the communication I/F 130.

[Example of operation]
Next, an example of the operation of the image forming apparatus 1 of the present embodiment 1 will be specifically described with reference to Figs. 3 to 6. Fig. 3 is a flowchart showing an example of the basic operation of the image forming apparatus 1 shown in Fig. 1. Fig. 4 is a flowchart showing an example of the operation of the print cutting process shown in Fig. 3. Fig. 5 is a timing chart showing a specific example of the relationship between the drive timing and the fixing temperature of the fixing unit 45 in the image forming apparatus 1 shown in Fig. 1. Fig. 6 is a diagram for explaining a specific example of the cutting process of the sheet S by the cutter 100 shown in Fig. 1. In the following description, a case where a sheet S of A4 size is cut by the cutter 100 after one-sided printing is performed is described as an example.

As shown in S11 of FIG. 3, the CPU 101 determines whether a print job has been received via the communication I/F 130. If the CPU 101 determines that a print job has been received via the communication I/F 130 (YES in S11), the CPU 101 proceeds to the process of S13, which will be described later.

On the other hand, if the CPU 101 determines that a print job has not been received via the communication I/F 130 (NO in S11), the process proceeds to S12. In S12, the CPU 101 determines whether input of a print command has been accepted via the operation panel 120. Then, if the CPU 101 determines that input of a print command has not been accepted via the operation panel 120 (NO in S12), the CPU 101 returns to the process of S11.

On the other hand, if the CPU 101 determines that a print command has been input via the operation panel 120 (YES in S12), the process proceeds to S13. In S13, the CPU 101 starts driving the heater 45H. For example, as shown in FIG. 5, the CPU 101 starts driving the heater 45H at time T1. In other words, it starts passing electricity through the heater 45H.

After starting to energize the heater 45H, in S14, the CPU 101 determines whether or not to cut the sheet S. Specifically, for example, when an input print job indicates that cutting processing is required to cut the sheet S with the cutter 100, the CPU 101 determines that cutting processing is to be performed on the sheet S (YES in S14) and proceeds to processing of S17. On the other hand, when the CPU 101 determines that cutting processing is not to be performed on the sheet S (NO in S14), the CPU 101 proceeds to processing of S15.

In S15, the CPU 101 moves the flapper FP to the first position and proceeds to processing in S16. As the flapper FP moves to the first position, the sheet S is distributed to the first discharge roller 38 side. Note that if the flapper FP is already in the first position at the start of S15, the CPU 101 maintains the flapper FP in the first position and proceeds to processing in S16.

In S16, the CPU 101 executes a printing process that does not involve cutting the sheet S. A detailed explanation of the printing process that does not involve cutting the sheet S is omitted, but the leading edge of the sheet on which the toner image has been formed and fixed is guided by the flapper FP to the first transport path H1 on which the first discharge roller 38 is installed. The sheet S guided to the first transport path H1 is discharged onto the discharge tray TR by the rotation of the first discharge roller 38.

On the other hand, if the CPU 101 determines that cutting processing is to be performed on the sheet S (YES in S14), in S17, the CPU 101 determines a cutting position CP (FIG. 6) for cutting the sheet S into two equal parts and stores it in the RAM 103. Specifically, as shown in FIG. 6, the CPU 101 determines the cutting position CP for dividing the A4 size sheet S0 into a first sheet and a second sheet that have equal lengths in the transport direction to be a position of the length in the transport direction from the leading edge, and stores it in the RAM 103.

The length to the cutting position CP is calculated based on, for example, the amount of transport of the sheet S detected by an encoder (not shown) from when the pre-registration sensor K2 detects the leading edge of the sheet S until the pre-registration sensor K2 detects the trailing edge of the sheet S.

In S18, the CPU 101 reads from the ROM 102 the printing temperature of the heating roller 45HR when fixing the image on the sheet S. The CPU 101 then sets the temperature of the heating roller 45HR to the printing temperature, for example, about 190°C, starts controlling the voltage applied to the heater 45H, and then proceeds to the process of S19.

In S19, the CPU 101 drives the main motor M0 in the forward direction, and then proceeds to the process of S20. This causes the pressure roller 45PR, the photosensitive drum 46, the developing roller 44R, and the registration roller 36 to rotate in a direction that transports the sheet S in the transport direction. As a result, for example, as shown in FIG. 5, when the pressure roller 45PR or the heating roller 45HR of the fixing unit 45 is driven to rotate at time T2, the temperature rise rate of the fixing temperature between the heating roller 45HR and the pressure roller 45PR, i.e., at the nip portion N, becomes slightly slower.

In S20, the CPU 101 moves the flapper FP to the second position and proceeds to the process of S21. By moving the flapper FP to the second position, the sheet S is distributed to the third transport path H3 and transported to the cutter 100 side.

In S21, the CPU 101 determines via the temperature sensor 45S whether the temperature of the heating roller 45HR has reached the temperature at which paper can be fed. The temperature at which the driving force of the main motor M0 can be transmitted to the pickup roller 32 is, for example, 170°C. If the CPU 101 determines via the temperature sensor 45S that the temperature of the heating roller 45HR has not reached the temperature at which paper can be fed (NO in S21), the process returns to S20, i.e., the process goes into standby mode.

On the other hand, if the CPU 101 determines through the temperature sensor 45S that the temperature of the heating roller 45HR has reached the temperature at which paper can be fed (YES in S21), the CPU 101 proceeds to processing in S22. In S22, the CPU 101 executes the sub-processing of the print cutting process, and then ends the process.

[Sub-processing of print cutting process]
Next, with reference to FIG. 4 as well, a specific example of the flow of the print cutting process executed by the CPU 101 in S22 will be described.

As shown in S31 of FIG. 4, the CPU 101 executes a pickup command to pick up the sheet S in the feed tray 31 with the pickup roller 32. Specifically, the CPU 101 turns on the electromagnetic clutch 107 and sets it to a transmission state in which the driving force of the main motor M0 is transmitted to the pickup roller 32. Then, the CPU 101 proceeds to the process of S32.

In S32, the CPU 101 determines whether the detection signal input from the post-registration sensor K3 has changed from an OFF signal to an ON signal. Specifically, the CPU 101 determines that the detection signal has changed to an ON signal by the post-registration sensor K3 detecting the leading edge of the conveyed sheet S and acquiring the detection signal sent from the post-registration sensor K3.

Then, if the detection signal input from the post-registration sensor K3 has not changed from an OFF signal to an ON signal (NO in S32), the CPU 101 returns to processing S32. On the other hand, if the detection signal input from the post-registration sensor K3 has changed from an OFF signal to an ON signal (YES in S32), the CPU 101 proceeds to processing S33.

In S33, the CPU 101 starts the image forming process on the sheet S by the image forming unit 4. Specifically, the CPU 101 controls the photosensitive drum 46 and the transfer roller 42R to form an image based on the print data on the sheet S. That is, the CPU 101 transfers the toner image formed on the photosensitive drum 46 to the sheet S by the transfer roller 42R. Then, the fixing unit 45 fixes the image formed on the sheet S to the sheet S.

Next, in S34, the CPU 101 starts driving the discharge motor M3 in the forward direction to rotate the second discharge roller 40A and the third discharge roller 40B, and proceeds to the process of S35. As a result, the sheet S is transported along the third transport path H3 toward the cutter 100, and the sheet S becomes ready for cutting by the cutter 100.

After S34, the CPU 101 determines whether the detection signal input from the paper discharge sensor K4 has changed from an OFF signal to an ON signal. Specifically, the CPU 101 determines that the detection signal has changed to an ON signal by acquiring the detection signal sent from the paper discharge sensor K4 after the paper discharge sensor K4 detects the leading edge of the conveyed sheet P.

In addition, the paper discharge sensor K4 is disposed downstream of the nip portion N in the conveying direction of the sheet S. Therefore, as shown at time T3 in FIG. 5, the detection signal from the paper discharge sensor K4 changes from an OFF signal to an ON signal with a slight delay after the leading edge of the sheet S passes through the nip portion N. Also, as shown at time T4 in FIG. 5, the detection signal from the paper discharge sensor K4 changes from an ON signal to an OFF signal with a slight delay after the trailing edge of the sheet S passes through the nip portion N.

Next, in S35, the CPU 101 executes a determination process to determine whether or not an image is to be formed at the cutting position CP of the sheet S. In other words, the CPU 101 executes the determination process before executing the cutting process by the cutter 100.

Specifically, in the judgment process of S35, the CPU 101 judges whether or not an image is formed at the cutting position CP of the sheet S based on the detection result of the detection sensor K5. Then, when the CPU 101 judges that the detection sensor K5 has detected that an image is formed at the cutting position CP (YES in S35), the process proceeds to S36. As a result, when the CPU 101 judges in the judgment process that an image is formed at the cutting position CP of the sheet S, it executes a suppression process to suppress adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process, as will be described in detail later.

On the other hand, if the CPU 101 determines that the detection sensor K5 has detected that no image has been formed at the cutting position CP (NO in S35), the process proceeds to S40. As a result, if the CPU 101 determines in the determination process that no image has been formed at the cutting position CP of the sheet S, it does not execute the suppression process that suppresses adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process.

Specifically, in S40, the CPU 101 determines whether the detection signal input from the paper discharge sensor K4 has changed from an ON signal to an OFF signal. In other words, the CPU 101 determines that the detection signal has become an OFF signal because the paper discharge sensor K4 has detected the leading edge of the conveyed sheet S, and then the trailing edge of the sheet S has passed, making it impossible to obtain the detection signal sent from the paper discharge sensor K4.

If the detection signal input from the paper discharge sensor K4 has not changed from an on signal to an off signal (NO in S40), the CPU 101 returns to the process of S40, that is, enters a standby state. On the other hand, if the detection signal input from the paper discharge sensor K4 has changed from an on signal to an off signal (YES in S40), the CPU 101 determines that the paper discharge sensor K4 has detected the completion of the passage of the sheet S, and proceeds to the process of S41.

For example, as shown in FIG. 5, when the detection signal input from the paper discharge sensor K4 changes from an ON signal to an OFF signal at time T4, the CPU 101 determines that the paper discharge sensor K4 has detected the completion of the passage of the sheet S. In other words, the CPU 101 determines that the trailing edge of the sheet S has passed through the nip portion N.

In S41, the CPU 101 reads from the ROM 102 the standby temperature of the heating roller 45HR when waiting for the sheet S to be transported. The CPU 101 then sets the target temperature of the heating roller 45HR to be lowered to the standby temperature, for example, about 130°C, starts controlling the voltage applied to the heater 45H, and proceeds to the process of S42. The standby temperature is a temperature lower than the printing temperature. For example, as shown in FIG. 5, the CPU 101 stops driving the heater 45H at time T5. At the timing of time T5, the sheet S has passed between the heating roller 45HR and the pressure roller 45PR, i.e., has passed through the nip portion N.

By processing S41, the CPU 101 controls the heater 45H so that the set temperature of the heating roller 45HR becomes the standby temperature, which is lower than the printing temperature, based on the time when the paper discharge sensor K4 detects the completion of the passage of the sheet S. When the paper discharge sensor K4 detects the passage of the sheet S, the sheet S has passed through the nip portion N, so it is preferable to lower the set temperature of the heating roller 45HR. In this case, the CPU 101 controls the heater 45H so that the set temperature of the heating roller 45HR becomes the standby temperature, which is lower than the printing temperature, so that the heating roller 45HR can be prevented from being heated locally.

In S42, the CPU 101 starts measuring the elapsed time from the point when the off signal is output from the paper discharge sensor K4. Next, the CPU 101 determines whether the elapsed time reaches a predetermined stop time, that is, whether the predetermined stop time has elapsed. The predetermined stop time is the elapsed time until the cutting position CP of the sheet S reaches the cutter position of the cutter 100. The predetermined stop time is stored in the ROM 102 in advance. For example, the predetermined stop time is the elapsed time starting from time T2 shown in FIG. 5.

If the CPU 101 determines that the time that has elapsed since the OFF signal was output from the paper discharge sensor K4 has not reached the specified stop time (NO in S42), the process returns to S42, i.e., the process enters a standby state. On the other hand, if the CPU 101 determines that the time that has elapsed since the OFF signal was output from the paper discharge sensor K4 has reached the specified stop time (YES in S42), the process proceeds to S43.

In S43, the CPU 101 stops the discharge motor M3, and then proceeds to the process of S44. The CPU 101 also stops the discharge motor M3, and the discharge drive of the sheet S is stopped. As a result, the second discharge roller 40A and the third discharge roller 40B stop with the sheet S clamped, and the sheet S stops with the cutting position CP positioned at the cutter position of the cutter 100. In other words, the CPU 101 stops the second discharge roller 40A and the third discharge roller 40B when the cutting position CP on the sheet S reaches the cutter position of the cutter 100.

By processing S42 and S43, the CPU 101 can stop the discharge motor M3 and stop the sheet S when a predetermined time has elapsed since the start of driving the discharge motor M3. This allows the CPU 101 to appropriately control the second discharge roller 40A and the third discharge roller 40B so that the cutting position CP on the sheet S reaches the cutter position of the cutter 100.

In S44, the CPU 101 drives the cutting motor M1 to move the blade 103A held by the cutter carriage back and forth in the width direction of the sheet S. This cuts the sheet S into two equal parts, a first sheet and a second sheet. After stopping the second discharge roller 40A and the third discharge roller 40B, the CPU 101 starts cutting the sheet S with the cutter 100 while driving the main motor M0 to rotate the heating roller 45HR or the pressure roller 45PR.

Here, an example of the fixing temperature of the heating roller 45HR will be described with reference to FIG. 5. When the CPU 101 sets the set temperature of the heater 45H to the standby temperature at time T5 and stops driving the heater 45H, the fixing temperature of the nip portion N starts to decrease from time T5, as shown in FIG. 5.

When the CPU 101 drives the cutting motor M1, the main motor M0 is being driven to rotate the heating roller 45HR or the pressure roller 45PR. Therefore, the fixing temperature of the nip N is lower than the fixing temperature of the nip N at time T5.

Therefore, after the rear end of the sheet S passes through the nip portion N at time T4, the heating roller 45HR and the pressure roller 45PR are in a rotating state even after the second discharge roller 40A and the third discharge roller 40B have stopped. This makes it possible to prevent the heating roller 45HR from locally increasing in temperature when the cutting motor M1 is driven. This makes it possible to prevent the durability of the fixing unit 45 from decreasing.

Next, in S45, the CPU 101 stops the main motor M0 when the preset driving duration of the main motor M0 has elapsed, and then proceeds to processing in S46.

For example, as shown in FIG. 5, at time T6, the CPU 101 stops the driving of the main motor M0, thereby stopping the heating roller 45HR and pressure roller 45PR of the fixing unit 45 and stopping the fixing drive. In this way, by stopping the driving of the main motor M0 when the driving of the main motor M0 is not necessary, the durability of the heating roller 45HR, pressure roller 45PR, etc. of the fixing unit 45 driven by the main motor M0 can be improved.

After cutting the sheet S, in S46, the CPU 101 resumes driving the discharge motor M3, rotates the second discharge roller 40A and the third discharge roller 40B, and discharges the cut first and second sheets, and then proceeds to processing of S47. In S47, the CPU 101 stops driving the discharge motor M3, and then proceeds to processing of S48.

By processing S44 to S47, the CPU 101 cuts the sheet S with the cutter 100, and then controls the discharge motor M3 to rotate the second discharge roller 40A and the third discharge roller 40B to discharge the cut sheet S. Then, after discharging the cut sheet S, the CPU 101 stops the second discharge roller 40A and the third discharge roller 40B. In this way, when it is not necessary to drive the second discharge roller 40A and the third discharge roller 40B, the second discharge roller 40A and the third discharge roller 40B are stopped, thereby suppressing noise caused by the second discharge roller 40A and the third discharge roller 40B.

In S48, the CPU 101 determines whether the print job being executed contains print data to be printed on the next sheet S. If the CPU 101 determines that the print job being executed does not contain print data to be printed on the next sheet S (NO in S48), the process ends. The next sheet S is the sheet S that is picked up from the feed tray 31 by the pickup roller 32 after the sheet S discharged by the second discharge roller 40A and the third discharge roller 40B.

On the other hand, if the CPU 101 determines that the ongoing print job contains print data to be printed on the next sheet S (YES in S48), it proceeds to processing of S49.

In S49, the CPU 101 reads from the ROM 102 the printing temperature of the heating roller 45HR when fixing the image on the sheet S. Then, the CPU 101 sets the set temperature of the heating roller 45HR to be increased to the printing temperature at time T7, starts controlling the voltage applied to the heater 45H, and then proceeds to the process of S50.

When performing continuous printing, the CPU 101 controls the heater 45H to the printing temperature after discharging the cut sheet S by processing S49. This allows the set temperature of the heating roller 45HR to be appropriately controlled for the printing process of the next sheet S, so that the image can be sufficiently fixed on the next sheet S.

In S50, if the main motor M0 is stopped, the CPU 101 restarts driving the main motor M0 to rotate the heating roller 45HR and pressure roller 45PR, etc., and then proceeds to processing of S51.

In S51, the CPU 101 determines via the temperature sensor 45S whether the temperature of the heating roller 45HR has reached the paper feed temperature. The paper feed temperature is a temperature higher than the standby temperature and lower than the print temperature. If the CPU 101 determines that the temperature of the heating roller 45HR has not reached the paper feed temperature (NO in S51), the CPU 101 returns to S51, i.e., enters the standby state.

On the other hand, if the CPU 101 determines that the temperature of the heating roller 45HR has reached the temperature at which paper can be fed (YES in S51), the process proceeds to S31. This causes the cutting process to be performed on the next sheet S that has been printed.

In addition, if the CPU 101 determines in the determination process of S35 that an image will be formed at the cutting position CP of the sheet S, the CPU 101 executes a suppression process in S36 to S39 to suppress adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process.

Specifically, in S36, the CPU 101 determines whether a predetermined first time has elapsed since the on-signal was input from the post-registration sensor K3. This first time is stored in the RAM 103 as appropriate, and is the time that defines the timing after the leading edge of the sheet S passes through the nip N. In addition to using the detection signal from the post-registration sensor K3, the first time can also be defined by the elapsed time from the on-signal was input from the pre-registration sensor K2 or the paper discharge sensor K4. In addition, in this embodiment 1, by defining the first time, as shown in FIG. 6, in the fixing process by the nip N, only the portion indicated by the dimension L1 (e.g., 30 mm) from the cutting position CP of the sheet S0 to the leading edge side of the sheet S0 can be locally heated.

If the CPU 101 determines that the first predetermined time has not elapsed since the ON signal was input from the post-registration sensor K3 (NO in S36), the process returns to S36, i.e., the process goes into standby mode.

On the other hand, if the CPU 101 determines that a predetermined first time has elapsed since the ON signal was input from the post-registration sensor K3 (YES in S36), the process proceeds to S37. In S37, the CPU 101 sets the set temperature of the heating roller 45HR to be increased to a first temperature higher than the printing temperature, starts controlling the voltage applied to the heater 45H, and then proceeds to the process of S38.

In S38, the CPU 101 determines whether a predetermined second time has elapsed since the ON signal was input from the post-registration sensor K3. The second time is stored in the RAM 103 as appropriate, and is the time that defines the timing after the rear end of the sheet S passes through the nip N. In addition to using the detection signal from the post-registration sensor K3, the second time can also be defined by the elapsed time from the ON signal was input from the pre-registration sensor K2 or the paper discharge sensor K4. In addition, in this embodiment 1, by defining the second time, as shown in FIG. 6, in the fixing process by the nip N, only the portion indicated by the dimension L2 (e.g., 30 mm) from the cutting position CP of the sheet S0 to the rear end side of the sheet S0 can be locally heated.

If the CPU 101 determines that the second predetermined time has not elapsed since the ON signal was input from the post-registration sensor K3 (NO in S38), the process returns to S38, i.e., the process goes into standby mode.

On the other hand, if the CPU 101 determines that a predetermined first time has elapsed since the ON signal was input from the post-registration sensor K3 (YES in S38), the process proceeds to S39. In S39, the CPU 101 sets the set temperature of the heating roller 45HR to be lowered from the first temperature to the printing temperature, starts controlling the voltage applied to the heater 45H, and then proceeds to the process of S40.

5, the CPU 101 starts the drive of the main motor M0 at time T8, thereby rotating the heating roller 45HR and the pressure roller 45PR of the fixing unit 45 and starting the fixing drive. After that, the CPU 101 determines that the detection signal from the paper discharge sensor K4 becomes an ON signal after a predetermined time lag after the leading edge of the sheet S passes through the nip portion N at time T9. After that, at time T10, the set temperature of the heating roller 45HR is increased to the first temperature. After that, the CPU 101 maintains the first temperature for a predetermined time obtained by subtracting the first time from the second time, and then at time T11, the set temperature of the heating roller 45HR is decreased to the printing temperature. In addition, the CPU 101 stops the drive of the heater 45H at time T12. At the timing of time T12, the sheet S has passed between the heating roller 45HR and the pressure roller 45PR, that is, has completed passing through the nip portion N. Furthermore, at time T13, the CPU 101 stops the heating roller 45HR and pressure roller 45PR of the fixing unit 45, ending the fixing drive.

Also, as shown at times T14 to T20 and times T21 to T26 in FIG. 5, the CPU 101 sequentially executes a determination process for the next sheet S and the sheet after that to determine whether an image will be formed at the cutting position CP of the sheet S, and a suppression process for suppressing adhesion of matter from the sheet S to the cutter 100 during the cutting process if the determination process determines that an image will be formed at the cutting position CP of the sheet S.

As described above, in the image forming apparatus 1 of the present embodiment 1, the CPU 101 executes a judgment process to judge whether or not an image is formed at the cutting position CP of the sheet S before executing the cutting process. Furthermore, if the CPU 101 determines in the judgment process that an image is formed at the cutting position CP of the sheet S, it executes a suppression process to suppress adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process. As a result, in the image forming apparatus 1 of the present embodiment 1, even if an image is formed at the cutting position CP of the sheet S, it is possible to suppress adhesion of foreign matter such as ink materials such as toner and paper powder from the sheet S to the cutter 100 during the cutting process, and it is possible to suppress a deterioration in the cutter characteristics such as the cutting performance and durability of the cutter 100.

In addition, in the image forming apparatus 1 of this embodiment 1, the CPU 101 executes the judgment process based on the detection result of the detection sensor K5, so the judgment process can be performed with high accuracy. As a result, in the image forming apparatus 1 of this embodiment 1, adhesion of foreign matter from the sheet S to the cutter 100 during cutting processing can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed.

In addition to the above description, for example, in S14, the CPU 101 may execute a judgment process to judge whether or not an image is formed at the cutting position CP of the sheet S based on the print data included in the input print job and printed on the sheet S by the image forming unit 4. In other words, the CPU 101 executes the judgment process when the image is in a state before it is formed at the cutting position CP. In this case, the CPU 101 can judge whether or not to proceed to S36 in S35 based on the result of the judgment process in S14. Therefore, adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed. In this case, the installation of the detection sensor K5 can also be omitted. However, the case where the detection sensor K5 is installed is preferable in that the CPU 101 can execute the judgment process in both states before the image is formed at the cutting position CP and after the image is formed at the cutting position CP, and the judgment process can be performed with high accuracy.

In addition to the above description, for example, in S12, the CPU 101 may execute a judgment process to judge whether an image is formed at the cutting position of the sheet S based on whether the print command received via the operation panel 120 includes a command to specify the cutting position CP of the sheet S. In this case, the CPU 101 can judge whether to proceed to S36 in S35 based on the result of the judgment process in S12. In other words, the CPU 101 can execute the judgment process when the image is in a state before it is formed at the cutting position CP. Therefore, it is possible to more reliably prevent foreign matter from adhering to the cutter 100 from the sheet S during the cutting process, and it is possible to more reliably prevent the deterioration of the cutter characteristics. In this case, the installation of the detection sensor K5 can be omitted. However, the case where the detection sensor K5 is installed is preferable in that the CPU 101 can execute the judgment process in both states before the image is formed at the cutting position CP and after the image is formed at the cutting position CP, and the judgment process can be performed with high accuracy.

In addition, in the image forming apparatus 1 of the present embodiment 1, as shown in S43 and S44, when the cutting position CP of the sheet S reaches the cutter position, the CPU 101 stops the second discharge roller 40A and the third discharge roller 40B, and then cuts the sheet S with the cutter 100. As a result, in the image forming apparatus 1 of the present embodiment 1, even if an image is formed at the cutting position CP of the sheet S, it is possible to prevent foreign matter from adhering to the cutter 100 from the sheet S during the cutting process, and to prevent a deterioration in the cutter characteristics.

In addition, in the image forming apparatus 1 of the present embodiment 1, as shown in S36 to S39, the CPU 101 controls the heater 45H as a suppression process by setting the target temperature of the heating roller 45HR to a first temperature higher than the print temperature according to the timing when the cutting position CP of the sheet S passes through the nip portion N. This allows the CPU 101 to increase the fixing strength by locally heating the cutting position CP of the sheet S during the suppression process. As a result, in the image forming apparatus 1 of the present embodiment 1, adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed.

In addition, in the image forming apparatus 1 of the present embodiment 1, as shown at times T9 and T10 in FIG. 5, the CPU 101 controls the heater 45H with the target temperature of the heating roller 45HR as the first temperature in a predetermined range after the leading edge of the sheet S passes through the nip portion N and before the trailing edge of the sheet S passes through the nip portion N. As a result, in the image forming apparatus 1 of the present embodiment 1, the CPU 101 can set the range in which the cutting position CP of the sheet S is locally heated to a predetermined range (for example, the range of dimensions L1 and L2 in FIG. 6). As a result, in the image forming apparatus 1 of the present embodiment 1, curling of the sheet S can be suppressed compared to heating the sheet S overall.

In addition, in the image forming apparatus 1 of the present embodiment 1, as shown in S36 to S39, the CPU 101 controls the heater 45H with the target temperature of the heating roller 45HR set as the first temperature based on the time point when the post-registration sensor K3 detects the sheet S. This allows the image forming apparatus 1 of the present embodiment 1 to more appropriately locally heat the cutting position CP of the sheet S in the suppression process.

In addition to the above description, the CPU 101 may slow the conveying speed of the sheet S when the suppression process is executed, compared to when the suppression process is not executed. Specifically, the CPU 101 may control the discharge motor M3 to change the rotation speed of the second discharge roller 40A and the third discharge roller 40B, thereby changing the conveying speed of the sheet S depending on whether the suppression process is executed or not. In this way, when the CPU 101 executes the suppression process, the conveying speed of the sheet S is slower than when the suppression process is not executed, so that the sheet S can be reliably cooled during conveyance of the sheet S. As a result, adhesion of foreign matter from the sheet S to the cutter 100 during cutting can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed.

[Modification 1]
Modification 1 of the present disclosure will be described below. For ease of explanation, the same reference numerals will be given to members having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

Figure 7 is a flowchart showing an example of the operation of the print cutting process in the image forming apparatus 1 according to the first modified example of the present disclosure. In Figure 7, the main difference between the first modified example and the first embodiment is that, as a suppression process, the CPU 101 stops the rotation of the second discharge roller 40A and the third discharge roller 40B for a predetermined time during the period from when the rear end of the sheet S passes through the nip portion N until the cutting position CP of the sheet S reaches the cutter position, and then rotates the second discharge roller 40A and the third discharge roller 40B again.

As shown in FIG. 7, in this first variation, between S34 and S42, CPU 101 executes S61 to S66. Specifically, in S61, CPU 101 determines whether the detection signal input from paper discharge sensor K4 has changed from an ON signal to an OFF signal. Specifically, CPU 101 determines that the detection signal has become an OFF signal by paper discharge sensor K4 detecting the rear end of the conveyed sheet P and acquiring the detection signal sent from paper discharge sensor K4.

If the detection signal input from the paper discharge sensor K4 has not changed from an on signal to an off signal (NO in S61), the CPU 101 returns to the process of S61, that is, enters a standby state. On the other hand, if the detection signal input from the paper discharge sensor K4 has changed from an on signal to an off signal (YES in S61), the CPU 101 determines that the paper discharge sensor K4 has detected the completion of the passage of the sheet S, and proceeds to the process of S62.

In S62, the CPU 101 sets the set temperature of the heating roller 45HR to the standby temperature by referring to the ROM 102. Then, in S63, the CPU 101 executes a determination process to determine whether or not an image is formed at the cutting position CP of the sheet S based on the detection result of the detection sensor K5, similar to S35. Then, if the CPU 101 determines that the detection sensor K5 has detected that an image is not formed at the cutting position CP (NO in S63), it proceeds to S42.

On the other hand, if the CPU 101 determines that the detection sensor K5 has detected that an image has been formed at the cutting position CP (YES in S63), the CPU 101 proceeds to S64. In S64, the CPU 101 stops driving the discharge motor M3.

In S65, the CPU 101 determines whether a predetermined time has elapsed since the discharge motor M3 was stopped. If the CPU 101 determines that the predetermined time has not elapsed since the discharge motor M3 was stopped (NO in S65), the CPU 101 returns to S65, i.e., enters a standby state.

On the other hand, if the CPU 101 determines that a predetermined time has elapsed since the discharge motor M3 was stopped (YES in S65), the process proceeds to S66. In S66, the CPU 101 restarts the drive of the discharge motor M3. This causes the second discharge roller 40A and the third discharge roller 40B to rotate again and transport the sheet S.

With the above configuration, this modified example 1 achieves the same effects as the first embodiment. Furthermore, in this modified example 1, the CPU 101 temporarily stops the transport of the sheet S that has passed through the nip portion N as a suppression process, so that the sheet S can be cooled reliably. As a result, in this modified example 1, adhesion of foreign matter from the sheet S to the cutter 100 during cutting processing can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed.

[Modification 2]
Modification 2 of the present disclosure will be described below. For ease of explanation, the same reference numerals will be given to members having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

Figure 8 is a flowchart showing an example of the operation of the print cutting process in the image forming apparatus 1 according to the second modification of the present disclosure. In Figure 8, the main difference between the second modification and the first embodiment is that, as a suppression process, the CPU 101 makes the length of the period from when the cutting position CP of the sheet S reaches the cutter position, to when the second discharge roller 40A and the third discharge roller 40B are stopped, and to when the cutting process is executed, longer when an image is formed at the cutting position CP of the sheet S than when an image is not formed at the cutting position CP of the sheet S.

As shown in FIG. 8, in this second variation, between S34 and S44, CPU 101 executes S71 to S76. Specifically, in S71, CPU 101 determines whether the detection signal input from paper discharge sensor K4 has changed from an ON signal to an OFF signal. Specifically, CPU 101 determines that the detection signal has become an OFF signal by paper discharge sensor K4 detecting the rear end of the conveyed sheet P and acquiring the detection signal sent from paper discharge sensor K4.

If the detection signal input from the paper discharge sensor K4 has not changed from an on signal to an off signal (NO in S71), the CPU 101 returns to the process of S71, that is, enters a standby state. On the other hand, if the detection signal input from the paper discharge sensor K4 has changed from an on signal to an off signal (YES in S71), the CPU 101 determines that the paper discharge sensor K4 has detected the completion of the passage of the sheet S, and proceeds to the process of S72.

In S72, CPU 101 sets the set temperature of heating roller 45HR to the standby temperature by referring to ROM 102. Then, in S73, CPU 101 determines whether a predetermined stop time has elapsed since the OFF signal was input from paper discharge sensor K4 in S71. If CPU 101 determines that the predetermined stop time has not elapsed since the OFF signal was input from paper discharge sensor K4 (NO in S73), it returns to S73, i.e., the standby state is entered.

On the other hand, if the CPU 101 determines that a predetermined stop time has elapsed since the OFF signal was input from the paper discharge sensor K4 (YES in S73), the process proceeds to S74. In S74, the CPU 101 stops driving the discharge motor M3. This causes the second discharge rollers 40A and the third discharge rollers 40B to stop transporting the sheet S.

In S75, similar to S35, the CPU 101 executes a determination process to determine whether or not an image is formed at the cutting position CP of the sheet S based on the detection result of the detection sensor K5. If the CPU 101 determines that the detection sensor K5 has detected that an image is not formed at the cutting position CP (NO in S75), the process proceeds to S44.

On the other hand, if the CPU 101 determines that the detection sensor K5 has detected that an image has been formed at the cutting position CP (YES in S75), the process proceeds to S76. In S76, the CPU 101 enters a standby state for a predetermined time. After that, the CPU 101 cancels the standby state when the predetermined time has elapsed, and proceeds to S44.

With the above configuration, this modified example 2 has the same effect as the first embodiment. In addition, in this modified example 2, the CPU 101 executes S76 as a suppression process, so that the length of the period from when the cutting position CP of the sheet S reaches the cutter position to when the second discharge roller 40A and the third discharge roller 40B are stopped and the cutting process is executed is longer when an image is formed at the cutting position CP of the sheet S than when an image is not formed at the cutting position CP of the sheet S. As a result, in this modified example 2, the CPU 101 temporarily waits for the sheet S before executing the cutting process on the sheet S that has reached the cutter position, and the sheet S can be reliably cooled. As a result, in this modified example 2, it is possible to more reliably suppress the adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process, and more reliably suppress the deterioration of the cutter characteristics.

[Embodiment 2]
A second embodiment of the present disclosure will be described below. For ease of explanation, the same reference numerals will be used to designate components having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

Fig. 9 is a diagram illustrating a schematic configuration of an image forming apparatus 1 according to a second embodiment of the present disclosure. In Fig. 9, the main difference between the second embodiment and the first embodiment is that a re-conveying path is provided for re-conveying the sheet S that has passed through the fixing unit 45 toward the image forming unit 4 so that double-sided printing can be performed on the sheet S, and the re-conveying path is used for suppression processing.

As shown in FIG. 9, in the image forming apparatus 1 of the present embodiment 2, a second transport path H2 is formed inside the housing 10 between the feed tray 31 and the image forming unit 4 and the fixing unit 45, as a re-transport path included in the transport path of the sheet S. One end and the other end of this second transport path H2 are connected to the first transport path H1 at the junction G1 and the junction G3, respectively, and the sheets S can be transported mutually.

Specifically, in the second conveying path H2, as conveying rollers for conveying the sheet S, for example, reverse conveying rollers 39A and reverse conveying rollers 39B are sequentially provided along the conveying direction in the second conveying path H2. In the second conveying path H2, the sheet S switched back from the junction G1 by the first discharge rollers 38 is sequentially conveyed toward the junction G3 by the reverse conveying rollers 39A and 39B. These reverse conveying rollers 39A and 39B are configured to rotate, for example, by the driving force from the main motor M0.

In the image forming device 1 of this embodiment 2, the sheet S that has passed through the fixing unit 45 and has had printing processing performed by the image forming unit 4 on either the front side (front surface) or back side is re-transported toward the photosensitive drum 46 by the second transport path H2 based on the operational instructions of the CPU 101.

In addition, in the image forming device 1 of this embodiment 2, the CPU 101 is configured to transport the sheet S that has passed through the fixing unit 45 to the second transport path H2, regardless of whether or not a double-sided printing process is performed on the sheet S, i.e., whether or not double-sided printing is performed, as a suppression process for suppressing adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process.

With the above configuration, the second embodiment achieves the same effects as the first embodiment. Furthermore, in the second embodiment, the CPU 101 passes the sheet S through the second transport path H2 during the suppression process, so that the sheet S passes through the fixing unit 45 twice, thereby increasing the fixing strength of the sheet S. As a result, in the second embodiment, it is possible to more reliably suppress the adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process, and more reliably suppress the deterioration of the cutter characteristics.

[Embodiment 3]
A third embodiment of the present disclosure will be described below. For ease of explanation, the same reference numerals will be given to members having the same functions as those described in the first embodiment, and the description thereof will not be repeated.

Figure 10 is a diagram illustrating a schematic configuration of an image forming device 1 according to a third embodiment of the present disclosure. In Figure 10, the main difference between the third embodiment and the first embodiment is that a fan F is provided in the housing 10 and is used for the suppression process.

As shown in FIG. 10, the image forming device 1 of this embodiment 3 is configured such that a fan F is provided above the fixing unit 45 inside the housing 10, and the CPU 101 drives the fan F to exhaust the air inside the housing 10 to the outside.

Specifically, the fan F is arranged so as to be connected to an opening formed in the outer wall of the housing 10 at one end of the width direction of the sheet S. One end of a duct (not shown) is also connected to the fan F. The other end of the duct is arranged inside the housing 10, near the fixing unit 45. The CPU 101 drives the fan F to exhaust air from inside the housing 10 through the duct.

A filter (not shown) is disposed between the fan F and the duct. In the image forming device 1, for example, even if dust such as paper powder is generated in the cutter 100, the fan F functions to suck the dust toward the filter, preventing the dust from scattering inside the housing 10 and collecting it with the filter.

In addition, in the image forming apparatus 1 of the present embodiment 3, the CPU 101 is configured to increase the drive speed of the fan F after the cutting position CP of the sheet S passes through the nip portion N as a suppression process for suppressing adhesion of foreign matter from the sheet S to the cutter 100 during the cutting process.

With the above configuration, the third embodiment provides the same effects as the first embodiment. Furthermore, in the third embodiment, the CPU 101 increases the drive speed of the fan F after the cutting position CP of the sheet S passes through the nip portion N, so that the sheet S can be cooled reliably. As a result, in the third embodiment, adhesion of foreign matter from the sheet S to the cutter 100 during cutting processing can be more reliably suppressed, and deterioration of the cutter characteristics can be more reliably suppressed.

In the above description, a configuration has been described in which a discharge motor M3 is provided to transmit driving force to the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B. However, the present disclosure is not limited to this, and for example, a configuration in which the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B are operated using the driving force of the main motor M0 may also be used.

However, as described above, providing the discharge motor M3 is preferable in that the CPU 101 can control the discharge motor M3 to independently control the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B, thereby allowing each of the first discharge roller 38, the second discharge roller 40A, and the third discharge roller 40B to operate more appropriately.

In the above description, the photosensitive drum 46 and the developing roller 44R are rotated by the driving force from the main motor M0. However, the present disclosure is not limited to this, and for example, the photosensitive drum 46 and the developing roller 44R may be driven by independent motors.

However, as described above, using the driving force of the main motor M0 to rotate the photosensitive drum 46 and the developing roller 44R is preferable because the CPU 101 can control the photosensitive drum 46 and the developing roller 44R by controlling the main motor M0, thereby allowing the image forming unit 4 to operate more appropriately.

In each of the above-described embodiments and modified examples, a configuration in which the cutter 100 is disposed in the third transport path H3 has been described. However, the present disclosure is not limited to this. For example, a configuration in which the cutter 100 is disposed in the first transport path H1, upstream of the first discharge roller 38 in the transport direction, without providing the third transport path H3 may also be used. In this case, the main body of the image forming device 1 can be made more compact.

This disclosure is not limited to the above-described embodiments and modifications, but various modifications are possible within the scope of the claims, and configurations obtained by appropriately combining the technical means disclosed in the embodiments and modifications are also included in the technical scope of this disclosure.

REFERENCE SIGNS LIST 1 Image forming apparatus 4 Image forming section 36 Registration roller 38 First discharge roller 40A Second discharge roller 40B Third discharge roller 42R Transfer roller 44R Development roller 45 Fixing section 45HR Heating roller (heating rotatable body)
45PR pressure roller (pressure rotating body)
46 Photosensitive drum 100 Cutter 101 CPU (control unit)
120 Operation panel (operation reception section)
130 Communication I/F (receiving unit)
C Control unit K5 Detection sensor F Fan M0 Main motor M3 Discharge motor N Nip portion H2 Second conveying path (re-conveying path)
S seat

Claims (16)

an image forming unit that forms an image on a sheet;
a discharge roller disposed downstream of the image forming unit in the sheet conveying direction for discharging the sheet to the outside of the image forming apparatus;
a cutter disposed at a cutter position downstream of the image forming unit in the conveying direction and configured to cut a sheet;
A control unit,
The control unit is
a cutting process in which the discharge rollers are rotated to transport the sheet that has passed through the image forming unit, the discharge rollers are stopped when a cutting position of the sheet reaches the cutter position, and then the sheet is cut by the cutter;
a determination process for determining whether or not an image is to be formed at a cutting position of the sheet before the cutting process is performed;
When it is determined in the determination process that an image is to be formed at the cutting position of the sheet, a suppression process is executed to suppress adhesion of foreign matter from the sheet to the cutter during the cutting process. a receiving unit for receiving a print job,
The control unit is
The image forming apparatus according to claim 1 , wherein the judgment process judges whether or not an image is to be formed at a cutting position of the sheet based on print data to be printed on the sheet by the image forming unit, the print job received by the receiving unit being included in the print data. A detection sensor for detecting an image formed on the sheet is further provided,
The control unit is
The image forming apparatus according to claim 1 , wherein the determination process determines whether or not an image is to be formed at the cutting position of the sheet based on a detection result of the detection sensor. An operation reception unit is further provided,
The control unit is
The image forming apparatus according to claim 1 , wherein the determination process determines whether or not an image is to be formed at the cutting position of the sheet based on the cutting position of the sheet accepted by the operation acceptance unit. a fixing unit that is disposed downstream of the image forming unit in the conveying direction and includes a heating rotator, a heater that heats the heating rotator, and a pressure rotator that forms a nip portion between the heating rotator and the pressure rotator, and fixes an image on the sheet;
A main motor that transmits a driving force to at least the heating rotor or the pressure rotor,
the discharge roller is disposed downstream of the fixing unit in the transport direction,
the cutter position is downstream of the fixing unit in the transport direction,
The control unit is
controlling the heater so that a target temperature of the heating rotator becomes a printing temperature for fixing an image on a sheet;
A motor control process is executed to control the main motor so as to rotate the heating rotator or the pressure rotator to transport a sheet,
2. The image forming apparatus according to claim 1, wherein, in the cutting process, the discharge roller is rotated to transport the sheet that has passed through the nip portion, and when the cutting position of the sheet reaches the cutter position, the discharge roller is stopped, and then the sheet is cut by the cutter. The control unit is
The image forming apparatus according to claim 5 , wherein the suppression process comprises controlling the heater to set a target temperature of the heating rotator to a first temperature higher than the printing temperature in accordance with a timing when a cutting position of the sheet passes through the nip portion. The control unit is
7. The image forming apparatus according to claim 6, wherein the heater is controlled with a target temperature of the heating rotator set to the first temperature within a predetermined range after the leading edge of the sheet has passed through the nip portion and before the trailing edge of the sheet has passed through the nip portion. The control unit is
7. The image forming apparatus according to claim 6, wherein after the cutting position of the sheet has passed through the nip portion, the heater is controlled with a target temperature of the heating rotatable body as the printing temperature. the image forming unit has a photosensitive drum,
a registration roller that is disposed upstream of the photosensitive drum in the conveying direction and is a conveying roller that is closest to the photosensitive drum among a plurality of conveying rollers that convey a sheet;
a sheet sensor disposed between the photosensitive drum and the registration roller in the conveying direction and capable of detecting the passage of a sheet;
The control unit is
7. The image forming apparatus according to claim 6, wherein the heater is controlled to set a target temperature of the heating rotatable member to the first temperature based on a time point when the sheet sensor detects the sheet. a re-transport path for re-transporting the sheet that has passed through the fixing unit toward the image forming unit,
The control unit is
The image forming apparatus according to claim 5 , wherein the suppression process comprises conveying the sheet that has passed through the fixing unit to the re-conveying path. The control unit is
6. The image forming apparatus of claim 5, wherein the suppression process includes stopping rotation of the discharge roller for a predetermined period of time during the period from when the trailing end of the sheet passes through the nip portion to when the cutting position of the sheet reaches the cutter position, and then rotating the discharge roller again. The control unit is
2. The image forming device of claim 1, wherein as the suppression process, the length of the period from when the cutting position of the sheet reaches the cutter position, after the discharge rollers are stopped, to when the cutting process is executed is made longer when an image is formed at the cutting position of the sheet than when an image is not formed at the cutting position of the sheet. The control unit is
The image forming apparatus according to claim 1 , wherein, when the suppression process is executed, a sheet conveying speed is made slower than when the suppression process is not executed. Further equipped with a fan that exhausts the air to the outside,
The control unit is
The image forming apparatus according to claim 5 , wherein the suppression process comprises increasing a drive speed of the fan after the cutting position of the sheet has passed through the nip portion. The image forming apparatus according to claim 1, further comprising a discharge motor that transmits a driving force to the discharge roller. the image forming unit includes a photosensitive drum, a developing roller that supplies toner to the photosensitive drum, and a transfer unit that transfers the toner supplied onto the photosensitive drum onto a sheet;
6. The image forming apparatus according to claim 5, wherein the photosensitive drum and the developing roller are rotated by a driving force from the main motor.

Images