Printing apparatus

Abstract

To provide a printing device capable of fixing an image on a sheet by strengthening fixing power. [Solution] When using the image forming unit 4 to print on one side of a sheet S, if the printer 1 is in normal mode, the CPU 101 forms an image on the first side of the sheet S, passes the sheet with the image formed on the first side through the fixing unit 6, and discharges the sheet S that has passed through the fixing unit 6; if the printer 1 is in fixing improvement mode (1), the CPU 101 forms an image on the first side of the sheet S, passes the sheet with the image formed on the first side through the fixing unit 6, and passes the sheet S that has passed through the fixing unit 6 again without forming an image on the second side of the sheet S, and then discharges it.

Description

[Technical Field]

[0001] The present application relates to a printing device capable of printing on sheets. [Background technology]

[0002] Patent Document 1 describes an image forming apparatus in which a toner image formed on a sheet is fixed by a fixing device. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2024-52146 Summary of the Invention [Problem to be solved by the invention]

[0004] To provide a printing device capable of fixing an image to a sheet with enhanced fixing power, for example, a printing device capable of printing a printed matter with such strong fixing power that the toner image on the printed matter with the fixed toner image is not easily blurred even when the printed matter's printed surface is rubbed with an eraser, for example. [Means for solving the problem]

[0005] In order to achieve the above object, the printing device described in the embodiment is a printing device comprising: a print engine capable of printing on a sheet by forming an image on the sheet using an electrophotographic method; a fuser located downstream of the print engine in the sheet transport path and fixing the image formed on the sheet by the print engine to the sheet; and a controller, wherein the printing device is capable of switching between a normal mode and an enhanced fixing mode, and the controller is capable of controlling the controller to, when using the print engine to print one-sided on a sheet, when the printing device is in the normal mode, form an image on the first side of the sheet, pass the sheet with the image formed on the first side into the fuser, and discharge the sheet that has passed through the fuser, and when the printing device is in the enhanced fixing mode, form an image on the first side of the sheet, pass the sheet with the image formed on the first side into the fuser, and pass the sheet that has passed through the fuser again without forming an image on the second side of the sheet before discharging it. Furthermore, a printing apparatus described in an embodiment is a printing apparatus including a print engine capable of printing on a sheet by forming an image on the sheet using an electrophotographic method, a fuser located downstream of the print engine in a sheet transport path and fuses the image formed on the sheet by the print engine to the sheet, and a controller, wherein the controller is capable of switching the printing apparatus to a normal mode, a first enhanced fusing mode, and a second enhanced fusing mode in accordance with a received instruction, and when performing single-sided printing on a sheet using the print engine, an image is formed on the first side of the sheet, and when the printing apparatus is in the normal mode When the printing device is in the first fixing strengthening mode, the image formed on the first side of the sheet is fixed by a first fixing method using a fixing device, and then the sheet is discharged outside the printing device; when the printing device is in the first fixing strengthening mode, the image formed on the first side of the sheet is fixed by a second fixing method using a fixing device, which is a fixing method with stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device; when the printing device is in the second fixing strengthening mode, the image formed on the first side of the sheet is fixed by a third fixing method using a fixing device, which is a fixing method with stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device. [Effects of the Invention]

[0006] According to the printing device described in the embodiment, when the printing device is in the enhanced fixing mode, it is possible to control the printing device to form an image on the first side of a sheet, pass the sheet with the image formed on the first side through a fixing device, and then pass the sheet that has passed through the fixing device through another fixing device before being discharged without forming an image on the second side of the sheet, thereby strengthening the fixing force and fixing the image to the sheet. Furthermore, according to the printing device described in the embodiment, when the printing device is in the first fixing enhancement mode, the image formed on the first side of the sheet is fixed by a second fixing method using a fixing device, which is a fixing method that provides stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device; and when the printing device is in the second fixing enhancement mode, the image formed on the first side of the sheet is fixed by a third fixing method using a fixing device, which is a fixing method that provides stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device.This makes it possible to fix the image to the sheet with stronger fixing power. [Brief explanation of the drawings]

[0007] [Figure 1] 1 is a cross-sectional view showing a schematic configuration of a monochrome laser printer according to an embodiment. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the monochrome laser printer of FIG. 1. [Figure 3] FIG. 10 is a diagram illustrating an example of a setting screen. [Figure 4] 10A to 10C are diagrams illustrating examples of modes that can be set in print result improvement settings and the operations of each mode. [Figure 5] 10 is a flowchart showing a procedure for print job processing. [Figure 6] 10 is a flowchart showing the procedure of a normal mode printing process. [Figure 7] 10 is a flowchart showing the procedure of an SX printing process. [Figure 8]10 is a flowchart showing the procedures of an image forming process and a sheet discharging process. [Figure 9] 10 is a flowchart showing the procedure of a DX printing process. [Figure 10] 10 is a flowchart showing a procedure for a sheet reversing process. [Figure 11] 10 is a flowchart showing the steps of a fixing improvement mode (2) printing process and a curl improvement mode printing process. [Figure 12] 10 is a flowchart showing the procedure of a fixing improvement mode (1) printing process. [Figure 13] 10 is a flowchart showing the procedure of the fixing improvement mode (1) SX printing process. [Figure 14] 10 is a flowchart showing the procedure of an image non-forming process. [Figure 15] 10 is a flowchart showing the procedure of a fixing improvement mode (1) DX printing process. [Figure 16] 10 is a flowchart showing the procedure for the fixing improvement mode (1) DX printing process (fixing improvement for the second side and face-up output). [Figure 17] 10 is a flowchart showing the procedure for the fixing improvement mode (1) SX printing process (face-down output). [Figure 18] 10 is a flowchart showing the procedure for the fixing improvement mode (1) DX printing process (fixing improvement for the second side and face-down output). [Figure 19] 10 is a flowchart showing the procedure for the DX printing process in the fixing improvement mode (1) (fixing improvement for the second side, changing the print order, and outputting face-up). DETAILED DESCRIPTION OF THE INVENTION

[0008] Hereinafter, embodiments of the present application will be described in detail with reference to the drawings.

[0009] FIG. 1 is a cross-sectional view showing the schematic configuration of a monochrome laser printer 1 according to one embodiment. The monochrome laser printer 1 is an example of a printing device. Hereinafter, the monochrome laser printer 1 will be abbreviated as printer 1. The printer 1 includes a main body casing 2, a conveying unit 3, an image forming unit 4, a fixing unit 6, and a user IF 102. "IF" is an abbreviation for Interface. The image forming unit 4 is an example of a print engine. Hereinafter, for convenience of explanation, the up-down direction and the front-rear direction of the printer 1 are defined as indicated by the arrows in FIG. 1. Furthermore, the left-right direction is defined as the direction from the front of the printer 1 to the left hand side of a user facing the printer 1, and the right hand side is defined as the right hand side.

[0010] The main body housing 2 has a front cover 21, a supply tray 31, a discharge tray 22, a conveying path 201, and a re-conveying path 202. The front cover 21 is attached to the front of the main body housing 2 in an openable and closable manner. The supply tray 31 is attached to the bottom of the main body housing 2 in an detachable manner. A sheet S is placed on the supply tray 31. The sheet S is a standard size sheet such as A4 size. The sheet S is, for example, a paper medium such as plain paper or cardboard, but is not limited to these, and may also be an OHP film. The discharge tray 22 is provided on the top of the main body housing 2, and a sheet S on which an image has been formed is placed on the discharge tray 22.

[0011] The conveying path 201 is a path for conveying the sheet S placed on the supply tray 31 toward the discharge tray 22 via the image forming unit 4. The re-conveying path 202 is a path for conveying the sheet S, on one side of which an image has been formed, in the direction opposite to the conveying direction, and conveying it again toward the image forming unit 4. The re-conveying path 202 branches off from the conveying path 201 at a branching position D1, and merges with the conveying path 201 at a merging position J near the pre-registration sensor SE1.

[0012] The conveying section 3 includes a pickup roller 33, a separation roller 34, a registration roller 35, a conveying roller 36, a discharge roller 85, re-conveying rollers 38 and 39, and a main motor 108 (see FIG. 2).

[0013] The pickup roller 33 picks up the sheets S in the supply tray 31 that have been pushed upward by the sheet pressure plate 32, and transports them toward the transport path 201. The separation roller 34 separates the sheets S picked up by the pickup roller 33 one by one.

[0014] The registration rollers 35 are disposed upstream of the image forming unit 4 on the conveying path 201. The registration rollers 35 align the direction of the leading edge of the sheet S, and then convey the sheet S toward the image forming unit 4. The conveying rollers 36 convey the sheet S, which has passed through the fixing unit 6, to the discharge rollers 85.

[0015] The discharge rollers 85 are disposed downstream of the junction C in the conveying path 201. The discharge rollers 85 are a pair of rollers consisting of a drive roller and a driven roller. The discharge rollers 85 rotate in the forward direction to discharge the sheet S onto the discharge tray 22. The forward rotation is a rotation that conveys the sheet S in the conveying direction, and corresponds to a counterclockwise rotation around the left-right direction of the main body housing 2 as an axis. The discharge rollers 85 also convey the sheet S to the re-conveying path 202 by reversing, which is a rotation opposite to the forward rotation. The reversing is a rotation that conveys the sheet S in the opposite direction to the conveying direction, and corresponds to a clockwise rotation around the left-right direction of the main body housing 2 as an axis.

[0016] Re-conveying rollers 38 and 39 are arranged on the re-conveying path 202. The re-conveying rollers 38 and 39 convey the sheet S conveyed to the re-conveying path 202 toward the image forming unit 4. The re-conveying rollers 38 and 39 re-convey the sheet S, on one side of which an image has been formed, toward the image forming unit 4 via the re-conveying path 202, thereby making it possible to form images on both sides of the sheet S.

[0017] The image forming unit 4 forms an image on a sheet S by electrophotography and is housed within the main body housing 2. The image forming unit 4 has a drum cartridge 5 and a laser unit 7. The drum cartridge 5 has a photosensitive drum 51, a toner storage unit 57, a supply roller 56, a developing roller 55, a charging roller 52, a transfer roller 53, and a pinch roller 54. The drum cartridge 5 can be removed from the main body housing 2 by opening the front cover 21. The pinch roller 54 of the drum cartridge 5 faces the registration roller 35. The pinch roller 54 rotates following the rotation of the registration roller 35 and transports the sheet S together with the registration roller 35.

[0018] The photosensitive drum 51 rotates clockwise by a driving force transmitted from a main motor 108 (see FIG. 2), thereby transporting the sheet S in the transport direction. In the photosensitive drum 51, the forward rotation, which is the rotation that transports the sheet S in the transport direction, is clockwise. Toner is stored in a toner storage section 57. A supply roller 56 supplies the toner in the toner storage section 57 to the developing roller 55. The charging roller 52 uniformly charges the surface of the photosensitive drum 51. Note that a scorotron type charger may be used instead of the charging roller 52.

[0019] A transfer roller 53 is disposed at a position facing the photosensitive drum 51. The transfer roller 53 forms a transfer nip TN between itself and the photosensitive drum 51 on the transport path 201. Note that a transfer belt may be used instead of the transfer roller 53.

[0020] The main body housing 2 has a laser unit 7 at its upper portion. The laser unit 7 has a polygon mirror 131 (see FIG. 2), a laser emission unit 132 (see FIG. 2), a lens, a reflecting mirror, etc. (not shown). The laser unit 7 exposes the surface of the photosensitive drum 51 by scanning the surface of the photosensitive drum 51 at high speed with a laser beam (see the two-dot chain line in FIG. 1) based on image data emitted from the laser emission unit 132.

[0021] An electrostatic latent image based on image data is formed on the surface of the photosensitive drum 51 by exposing it to light with the laser unit 7. The developing roller 55 supplies toner to the electrostatic latent image formed on the surface of the photosensitive drum 51, thereby forming a toner image on the surface of the photosensitive drum 51.

[0022] A transfer voltage is applied to the transfer roller 53 by a voltage application unit (not shown). The transfer roller 53 transports the sheet S between itself and the photosensitive drum 51, thereby transferring the toner image formed on the surface of the photosensitive drum 51 onto the sheet S passing through the transfer nip TN. In this way, an image is formed on the sheet S.

[0023] A fixing unit 6 is disposed downstream of the image forming unit 4 on the conveying path 201. The fixing unit 6 has a heating roller 61, a pressure roller 62, a heater 63, and a temperature sensor 64 (see FIG. 2). The heating roller 61 heats the sheet S. The pressure roller 62 forms a nip N between itself and the heating roller 61 and applies pressure to the sheet S. The pressure roller 62 rotates counterclockwise by the driving force of the main motor 108. The forward rotation of the pressure roller 62, which is the rotation that conveys the sheet S in the conveying direction, is the counterclockwise direction.

[0024] Heater 63 is, for example, a halogen heater, and heats heating roller 61. Temperature sensor 64 is provided near heating roller 61 and detects the temperature of heating roller 61. Temperature sensor 64 outputs a signal corresponding to the detected temperature to CPU 101.

[0025] The fixing device 6 heats the sheet S with the heating roller 61 and rotates the pressure roller 62, thereby conveying the sheet S while applying pressure with the heating roller 61 and the pressure roller 62, thereby fixing the image formed on the sheet S by the image forming unit 4 to the sheet S.

[0026] Although the fixing unit 6 has been described as including the heating roller 61, the pressure roller 62, and the heater 63, the invention is not limited to this. For example, the fixing unit 6 may have a heater, a nip plate that receives radiant heat from the heater, a heating belt that rotates around the nip plate, and a pressure roller.

[0027] The fixing unit 6 may also have a substrate on which a heat generating pattern is formed, a belt that rotates around the substrate, and a pressure roller, so that the substrate and the belt are in contact with each other.The fixing unit 6 may also have a heating roller, a heater, and a pressure belt.

[0028] Next, the electrical configuration of the printer 1 will be described with reference to Fig. 2. As shown in Fig. 2, the printer 1 further includes an ASIC 100, a memory 103, and a communication IF 104.

[0029] The ASIC 100 is electrically connected to a user IF 102, a memory 103, a communication IF 104, an electromagnetic clutch 107, a main motor 108, a pre-registration sensor SE1, a post-registration sensor SE2, a discharge sensor SE3, a drum cartridge 5, a fixing unit 6, and a laser unit 7.

[0030] The ASIC 100 is equipped with a CPU 101. The CPU 101 is an example of a controller and performs overall control of each unit of the printer 1. The CPU 101 executes various processes in accordance with a control program 103A read from the memory 103 and based on user operations. Note that the printer 1 may include not only a single piece of hardware as the CPU 101, but also multiple pieces of hardware corresponding to each function. The memory 103 stores various programs and various data, including the control program 103A and setting information 103B. The control program 103A is a program that causes the printer 1 to perform various operations. Details of each program and data will be described later with reference to FIGS. 4 to 21. The memory 103 is also used as a work area when various processes are executed. A buffer provided in the CPU 101 is also an example of a memory. The setting information 103B includes information stored in a volatile memory such as a RAM and information stored in a non-volatile memory such as an NVRAM.

[0031] Note that examples of memory 103 are not limited to ROM, RAM, NVRAM, HDD, etc. built into printer 1, but may also be storage media readable and writable by CPU 101. For example, external memory such as a USB memory or HDD connected to printer 1 via communication IF 104, or a memory or HDD provided in a device connected to printer 1 via communication IF 104, are also examples of memory 103. Note that computer-readable storage media are non-transitory media. In addition to the above examples, non-transitory media also include storage media such as CD-ROMs and DVD-ROMs. Non-transitory media are also tangible media. On the other hand, electrical signals carrying programs downloaded from a server on the Internet are computer-readable signal media, which is a type of computer-readable medium, but are not included in non-transitory computer-readable storage media.

[0032] The user IF 102 is disposed, for example, on the top surface of the main body housing 2. The user IF 102 is an interface that exists between the user who operates the printer 1 and the CPU 101, and has, for example, a touch panel or operation keys that are physical keys. The user IF 102 accepts user operations and outputs the accepted information to the CPU 101.

[0033] The communication IF 104 is connected to a network (not shown) such as a LAN, and enables connection to an external device such as a PC 200 incorporating a driver for the printer 1. The CPU 101 can receive a print job via the communication IF 104. The print job includes various information required to form an image on the sheet S, such as image data for image formation and driver settings (described later).

[0034] The main motor 108 transmits a driving force to the conveying unit 3, the pressure roller 62, and the drum cartridge 5. When the CPU 101 drives the main motor 108 to rotate in the forward direction, a first driving force is transmitted to the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35. Then, the pressure roller 62, the photosensitive drum 51, the developing roller 55, the pickup roller 33, and the registration roller 35 rotate in a direction to convey the sheet S in the conveyance direction.

[0035] Specifically, the pressure roller 62 rotates counterclockwise. The photosensitive drum 51 rotates clockwise. The developing roller 55 rotates counterclockwise. The pickup roller 33 rotates counterclockwise. The registration roller 35 rotates counterclockwise.

[0036] On the other hand, even if the CPU 101 drives the main motor 108 in the reverse direction, the second driving force is not transmitted to the pressure roller 62, the drum cartridge 5, the pickup roller 33, and the registration roller 35.

[0037] Furthermore, the CPU 101 drives the main motor 108 in the forward direction to transmit a first driving force to the discharge roller 85, causing the discharge roller 85 to rotate counterclockwise. On the other hand, the CPU 101 drives the main motor 108 in the reverse direction to transmit a second driving force to the discharge roller 85, causing the discharge roller 85 to rotate clockwise.

[0038] Furthermore, the CPU 101 drives the main motor 108 in the forward direction to transmit a first driving force to the re-conveying rollers 38 and 39, causing them to rotate clockwise. On the other hand, the CPU 101 drives the main motor 108 in the reverse direction to transmit a second driving force to the re-conveying rollers 38 and 39, causing them to rotate clockwise.

[0039] The electromagnetic clutch 107 is controlled by the CPU 101. By turning on the electromagnetic clutch 107, the CPU 101 brings about a state in which the driving force of the main motor 108 is transmitted to the pickup roller 33, and by turning off the electromagnetic clutch 107, the CPU 101 brings about a state in which the driving force of the main motor 108 is not transmitted to the pickup roller 33.

[0040] The pre-registration sensor SE1 is disposed upstream of the registration rollers 35 on the conveying path 201, and is a sensor that detects the passage of the sheet S. The pre-registration sensor SE1 may be a sensor having an actuator that oscillates when the sheet S comes into contact with it, or an optical sensor. The pre-registration sensor SE1 outputs an ON signal when the sheet S is passing, and outputs an OFF signal when the sheet S is not passing. The detection signal from the pre-registration sensor SE1 is output to the CPU 101.

[0041] The post-registration sensor SE2 is disposed upstream of the fixing unit 6 on the conveying path 201, specifically between the registration roller 35 and the transfer roller 53, and is a sensor that detects the passage of the sheet S. The post-registration sensor SE2 has the same configuration as the pre-registration sensor SE1. A detection signal from the post-registration sensor SE2 is output to the CPU 101.

[0042] The discharge sensor SE3 is disposed between the fixing unit 6 and the conveying roller 36 on the conveying path 201, and detects the passage of the sheet S. The discharge sensor SE3 has the same configuration as the pre-registration sensor SE1. A detection signal from the discharge sensor SE3 is output to the CPU 101.

[0043] Next, a print result improvement function, one of the special functions provided in the printer 1, will be described with reference to FIG. 3. FIG. 3(a) shows an example of a setting screen 210 for a driver installed in the PC 200. The driver is software used to create a print job (described later) and send the print job to the printer 1. The driver may create and send the print job in conjunction with an operating system installed in the PC 200. The setting screen 210 displays a function selection area 211 in which one of multiple functions included in other special functions can be selected. The example in FIG. 3(a) shows the state in which the "Improve Print Result" function has been selected from the various functions displayed in the function selection area 211. The "Improve Print Result" function allows the user to select one of the following options: "Apply Device Settings," "Off," "Reduce Paper Curl," "Improve Toner Fixation (2)," and "Improve Toner Fixation (1)." Selection is made by turning on / off a radio button 212 displayed adjacent to each option using a user interface such as a mouse (not shown). In the example of FIG. 3(a), "Apply device settings" is selected. Then, when OK button 213 is operated, setting information indicating the options selected on driver setting screen 210 is stored in memory (not shown) of PC 200. Based on the setting information stored in memory, PC 200 generates a print job including information indicating the options selected on driver setting screen 210 (for convenience, referred to as driver settings), and transmits the print job to printer 1. On the other hand, when cancel button 214 is operated, PC 200 ends display of setting screen 210 without storing the setting information in memory.

[0044] The print result improvement function can also be configured from the user IF 102 of the printer 1. FIG. 3B shows an example of a setting screen 102A for the print result improvement function displayed on the user IF 102. The setting screen 102A allows users to select four options from the options available on the setting screen 210 of FIG. 3A, excluding "Apply Device Settings." Labels 102A1 indicating each option are displayed on the setting screen 102A, and any option can be selected by, for example, touching any of the labels 102A1. In the example of FIG. 3B, "Off" is selected. The CPU 101 stores information indicating which option of the print result improvement function was selected via the setting screen 102A in the memory 103 as setting information 103B.

[0045] Hereinafter, when any of "Off," "Reduce Paper Curl," "Improve Toner Fixation (2)," and "Improve Toner Fixation (1)" is selected, the printer 1 is in the "Normal Mode," "Curl Reduction Mode," "Fixing Improved Mode (2)," and "Fixing Improved Mode (1)," respectively. Note that "Fixing Improved Mode (1)" is a mode that fixes an image to the sheet S with even stronger fixing power than "Fixing Improved Mode (2)."

[0046] 4 shows improvement settings (modes) that can be set in the print result improvement function, and examples of operation of the printer 1 for each improvement setting. The contents shown in FIG. 4 are used in the print job processing of FIG.

[0047] Next, the operation of the printer 1 will be described with reference to a flowchart. Note that the following processing refers to processing by the CPU 101 in accordance with instructions written in a program. That is, in the following description, processes such as "determination," "extraction," "selection," "calculation," "decision," "identification," "acquisition," "reception," and "control" refer to processing by the CPU 101. Processing by the CPU 101 also includes hardware control using the OS API. In this specification, the operation of each program will be described without mentioning the OS. That is, in the following description, a statement to the effect that "program B controls hardware C" may also mean that "program B controls hardware C using the OS API." Also, processing by the CPU 101 in accordance with instructions written in a program may be described in abbreviated terms, such as "performed by the CPU 101."

[0048] Note that "acquire" is used as a concept that does not require a request. In other words, the process of CPU 101 receiving data without a request is also included in the concept of "CPU acquires data." Furthermore, "data" in this specification is represented by a bit string that can be read by a computer. Data that has the same substantial meaning but different formats is treated as the same data. The same applies to "information" in this specification. Furthermore, "request" and "instruct" are concepts that indicate outputting information indicating a request or an instruction to the other party. Furthermore, information indicating a request or an instruction is also simply referred to as a "request" or "instruction."

[0049] Furthermore, the process by CPU 101 to determine whether information A indicates event B may be conceptually described as "determining whether event B is present from information A." The process by CPU 101 to determine whether information A indicates event B or event C may be conceptually described as "determining whether event B or event C is present from information A."

[0050] 5 shows the procedure for print job processing executed by printer 1, particularly CPU 101. Print job processing is initiated, for example, when CPU 101 acquires a print job. The print job may be acquired by receiving a print job output by PC 200 via communication IF 104, or by reading a print job already stored in memory 103. Hereinafter, in the explanation of each process, steps will be represented as "S."

[0051] In FIG. 5, CPU 101 determines whether the driver setting included in the print job is "Apply Device Settings" (S10). For convenience, "XX" is described to indicate that "XX" has been selected. The process of determining the driver setting, including S10, may be the following process. For example, printer 1 may acquire driver settings before acquiring a print job and store them in memory 103, for example. In this configuration, CPU 101 may determine which option has been selected based on driver information previously stored in memory. PC 200 may also be configured to send a print job to printer 1 using software other than the driver, for example, an application, that includes setting information indicating the selected option. In this configuration, CPU 101 may determine which option has been selected based on setting information included in the print job.

[0052] If it is determined in S10 that the driver setting is "Apply main body setting" (S10: YES), CPU 101 determines whether the main body setting is "Off," "Fixing improvement mode (2)," "Curl improvement mode," or "Fixing improvement mode (1)" (S20). Note that if the print job does not include driver settings, CPU 101 may determine S10: YES. If the main body setting is "off" (S20: off), CPU 101 executes normal mode printing processing (S21), if the main body setting is "fixing improvement mode (2)" (S20: fixing improvement mode (2)), CPU 101 executes fixing improvement mode (2) printing processing (S22), if the main body setting is "curl improvement mode" (S20: curl improvement mode), CPU 101 executes curl improvement mode printing processing (S23), and if the main body setting is "fixing improvement mode (1)" (S20: fixing improvement mode (1)), CPU 101 executes fixing improvement mode (1) printing processing (S24). After executing each printing processing (S21 to S24), CPU 101 ends the print job processing.

[0053] On the other hand, if the driver setting is not "Apply main body setting" in the determination of S10 (S10: NO), CPU 101 determines whether the driver setting is "Off," "Fixing improvement mode (2)," "Curl improvement mode," or "Fixing improvement mode (1)" (S30). If the driver setting is "Off" (S30: Off), CPU 101 executes normal mode printing processing (S31). If the driver setting is "Fixing improvement mode (2)" (S30: Fixing improvement mode (2)), CPU 101 executes fixing improvement mode (2) printing processing (S32). If the driver setting is "Curl improvement mode" (S30: Curl improvement mode), CPU 101 executes curl improvement mode printing processing (S33). If the driver setting is "Fixing improvement mode (1)" (S30: Fixing improvement mode (1)), CPU 101 executes fixing improvement mode (1) printing processing (S34). After executing each printing process (S31 to S34), CPU 101 ends the print job process.

[0054] FIG. 6 shows the detailed procedure of the normal mode printing process in S21. In FIG. 6, CPU 101 determines whether to SX print the print job (S40). Here, SX is an abbreviation for Simplex, and SX printing means single-sided printing. Whether to SX print the print job may be determined based on instruction information included in the print job, or based on an operation received from the user via user IF 102. If the print job is to be SX printed (S40: YES), CPU 101 executes SX printing processing (S41) and then terminates the normal mode printing process. On the other hand, if the print job is not to be SX printed (S40: NO), that is, if the print job is to be DX printed, CPU 101 executes DX printing processing (S42) and then terminates the normal mode printing process. Here, DX is an abbreviation for Duplex, and DX printing means double-sided printing.

[0055] FIG. 7 shows the procedure for the SX printing process in S41. In FIG. 7, CPU 101 sets the target temperature (target value of the fixing temperature) of fuser 6 to the normal temperature (S50). In parallel with the process shown in the flowchart, CPU 101 performs a process to control the temperature of fuser 6 to the target temperature. For example, CPU 101 controls the on / off of heater 63 of fuser 6 and the on / off of an air-cooling fan (not shown). Here, the normal temperature varies depending on the environment in which printer 1 is located, including the temperature around printer 1 (ambient temperature). However, as shown in *1 in FIG. 4, if the environment in which printer 1 is located is the same, the normal temperature is higher than the curl improvement mode temperature (described later) and lower than the fixing improvement mode (2) temperature (described later).

[0056] Next, the CPU 101 drives the main motor 108 in the forward direction (S51). Here, the rotation speed of the main motor 108 is determined based on the size and type of the sheet S to be printed, as shown in *2 in FIG. 4, and other special settings. For example, if the size of the sheet S is A4, the rotation speed of the main motor 108 is set to full speed, and if the size of the sheet S is A5 portrait, the rotation speed is set to half speed. Furthermore, if the sheet type of the sheet S is plain paper, the rotation speed of the main motor 108 is set to full speed, and if the sheet type of the sheet S is cardboard, the rotation speed is set to half speed. Furthermore, if a silent mode is set as a special setting, the rotation speed of the main motor 108 is set to half speed. Note that the rotation speed of the main motor 108 is not limited to full speed and half speed, but may be a speed between full speed and half speed, or may be a speed less than half speed. Alternatively, the rotation speed is not limited to two speeds, but may be set to one of three or more speeds.

[0057] Next, CPU 101 executes image formation processing (S52). Fig. 8(a) shows the detailed procedure of the image formation processing. In Fig. 8(a), CPU 101 executes a pickup command (S60). As a result, CPU 101 turns on electromagnetic clutch 107.

[0058] Next, CPU 101 waits until the post-registration sensor SE2 (see FIG. 1) switches from off to on (S61: NO). As described above, post-registration sensor SE2 is disposed between registration roller 35 and transfer roller 53 on conveyance path 201, and outputs an on signal when sheet S is passing through, and outputs an off signal when sheet S is not passing through. Therefore, in S61, CPU 101 waits until post-registration sensor SE2 detects the leading edge of sheet S. Then, when post-registration sensor SE2 detects the leading edge of sheet S (S61: YES), CPU 101 starts image formation on sheet S, i.e., transfer and fixation of a toner image (S62).

[0059] Next, CPU 101 waits until the discharge sensor SE3 (see FIG. 1) switches from on to off (S63: NO). As described above, discharge sensor SE3 is disposed between the fixing unit 6 and the conveying rollers 36 on the conveying path 201, and outputs an on signal when sheet S is passing, and outputs an off signal when sheet S is not passing. Therefore, in S63, CPU 101 waits until discharge sensor SE3 detects the trailing edge of sheet S. Then, when discharge sensor SE3 detects the trailing edge of sheet S (S63: YES), the image forming process ends.

[0060] Returning to FIG. 7, CPU 101 executes sheet discharge processing (S53). FIG. 8(b) shows detailed procedures for the sheet discharge processing. In FIG. 8(b), CPU 101 waits until a predetermined time has elapsed (S68: NO). The predetermined time is the time assumed by the developer of printer 1 as the time that elapses from when discharge sensor SE3 detects the trailing edge of sheet S until sheet S is discharged to discharge tray 22. Specifically, this time is the time obtained by adding a predetermined margin to the time obtained by dividing the conveyance distance from the installation position of discharge sensor SE3 on conveyance path 201 to the downstream end by the conveyance speed of sheet S.

[0061] 7, CPU 101 determines whether the job being executed includes printing of a next sheet (S54). If the determination indicates that there is a next sheet to be printed (S54: YES), CPU 101 returns the process to S52 and repeats the processes from S52 onward. On the other hand, if there is no next sheet to be printed (S54: NO), CPU 101 stops main motor 108 (S55) and then ends the SX printing process.

[0062] Fig. 9 shows the detailed procedure of the DX printing process of S42 above. In Fig. 9, similarly to S50 and S51 above (see Fig. 7), the CPU 101 sets the target temperature (target value of the fixing temperature) of the fixing unit 6 to the normal temperature (S70), and drives the main motor 108 in the forward direction (S71).

[0063] Next, the CPU 101 executes image forming processing on the first side of the sheet S (S72). Details of the image forming processing have been explained based on FIG. 8(a), so they will not be explained again.

[0064] Next, CPU 101 executes sheet inversion processing. FIG. 10 shows the detailed procedure of the sheet inversion processing. In FIG. 10, CPU 101 waits until sheet S reaches the inversion position (S80: NO). The inversion position is, for example, switchback position D2 (see FIG. 1) on conveying path 201, downstream in the conveying direction from branch position D1 (see FIG. 1). Then, in S80, CPU 101 determines whether the trailing edge of sheet S has reached switchback position D2. Specifically, while executing image forming processing (first side) in S72, CPU 101 determines whether a predetermined time has elapsed, starting from the time when "YES" is determined in S63. Here, the predetermined time is the time obtained by dividing the conveying distance from the installation position of discharge sensor SE3 on conveying path 201 to switchback position D2 by the conveying speed of sheet S.

[0065] Then, when the sheet S reaches the reversing position (S80: YES), the CPU 101 drives the main motor 108 in the reverse direction (S81). As a result, the sheet S is conveyed in the reverse direction along the conveying path 201, passes through the branching position D1 and the re-conveying path 202, and is conveyed again from the merging position J to the conveying path 201. The CPU 101 waits until the post-registration sensor SE2 switches from off to on (S82: NO), as in the above S61 (see FIG. 8(a)). Then, when the post-registration sensor SE2 switches from off to on and detects the leading edge of the sheet S (S82: YES), the CPU 101 ends the sheet reversing process.

[0066] Returning to FIG. 9, CPU 101 executes image formation processing on the second side of sheet S (S74). The second side is the side opposite to the first side of the same sheet S. Then, CPU 101 executes sheet discharge processing (S75) in the same manner as in S53 (see FIG. 7) above.

[0067] Next, the CPU 101 determines whether the job being executed includes printing of a next sheet (S76), in the same manner as in S54 (see FIG. 7). If the determination indicates that the next sheet is to be printed (S76: YES), the CPU 101 returns the process to S72 and repeats the processes from S72 onward. On the other hand, if the next sheet is not to be printed (S76: NO), the CPU 101 stops the main motor 108 (S77) and then ends the DX printing process.

[0068] FIG. 11(a) shows the detailed procedure of the fixing improvement mode (2) printing process of S22 (see FIG. 5) above. In FIG. 11(a), the same steps as in FIG. 6 are assigned the same step numbers. In FIG. 11(a), if the print job is to be SX printed (S40: YES), CPU 101 executes the fixing improvement mode (2) SX printing process (S101), and if the print job is to be DX printed (S40: NO), CPU 101 executes the fixing improvement mode (2) DX printing process (S102). After executing each printing process (S101, S102), CPU 101 ends the fixing improvement mode (2) printing process.

[0069] The fixing improvement mode (2) SX printing process can be achieved by changing the process in S50 of the SX printing process in Figure 7, from "Set the target temperature of the fixing unit 6 (target fixing temperature) to the normal temperature" to "Set the target temperature of the fixing unit 6 (target fixing temperature) to the fixing improvement mode (2) temperature." On the other hand, the fixing improvement mode (2) DX printing process can be achieved by changing the process in S70 of the DX printing process in Figure 9, from "Set the target temperature of the fixing unit 6 (target fixing temperature) to the normal temperature" to "Set the target temperature of the fixing unit 6 (target fixing temperature) to the fixing improvement mode (2) temperature." Here, as described above based on *1 in Figure 4, the fixing improvement mode (2) temperature is a temperature higher than the normal temperature if the environment in which the printer 1 is placed is the same.

[0070] In this way, in the fixing improvement mode (2) printing process, the image on the sheet S is fixed to the sheet S at a fixing temperature higher than the fixing temperature in the normal mode printing process, so the fixing strength of the image on the sheet S can be made higher than the fixing strength in the normal mode printing process.

[0071] FIG. 11(b) shows detailed steps of the curl reduction mode printing process of S23 (see FIG. 5) above. In FIG. 11(b), the same steps as in FIG. 6 are assigned the same step numbers. In FIG. 11(b), if the print job is to be SX printed (S40: YES), CPU 101 executes curl reduction mode SX printing process (S111), and if the print job is to be DX printed (S40: NO), CPU 101 executes curl reduction mode DX printing process (S112). After executing each printing process (S111, S112), CPU 101 ends the curl reduction mode printing process.

[0072] The curl reduction mode SX printing process can be achieved by changing the process of S50 in the SX printing process in Figure 7 from "Set the target temperature of the fuser unit 6 (target fixing temperature) to the normal temperature" to "Set the target temperature of the fuser unit 6 (target fixing temperature) to the curl reduction mode temperature." On the other hand, the curl reduction mode DX printing process can be achieved by changing the process of S70 in the DX printing process in Figure 9 from "Set the target temperature of the fuser unit 6 (target fixing temperature) to the normal temperature" to "Set the target temperature of the fuser unit 6 (target fixing temperature) to the curl reduction mode temperature." Here, as described above based on *1 in Figure 4, the curl reduction mode temperature is a temperature lower than the normal temperature if the environment in which the printer 1 is placed is the same.

[0073] In this way, in the curl improvement mode printing process, the image on the sheet S is fixed to the sheet S at a fixing temperature lower than the fixing temperature in the normal mode printing process, so although the fixing strength of the image on the sheet S is lower than the fixing strength in the normal mode printing process, the curl of the sheet S can be reduced more than the curl of the sheet S that occurs in the normal mode printing process.

[0074] FIG. 12 shows detailed steps of the fixing improvement mode (1) printing process in S24 (see FIG. 5) above. In FIG. 12, the same steps as in FIG. 6 are assigned the same step numbers. In FIG. 12, if the print job is to be SX printed (S40: YES), CPU 101 executes the fixing improvement mode (1) SX printing process (S121), and if the print job is to be DX printed (S40: NO), CPU 101 executes the fixing improvement mode (1) DX printing process (S122). After executing each printing process (S121, S122), CPU 101 ends the fixing improvement mode (1) printing process.

[0075] FIG. 13 shows the detailed procedure for the fixing improvement mode (1) SX printing process. In FIG. 13, the same steps as those in FIG. 7 are assigned the same step numbers, and the description of those steps will be omitted as appropriate. In FIG. 13, the CPU 101 sets the target temperature (target value of the fixing temperature) of the fixing unit 6 to the fixing improvement mode (1) temperature (S130). Here, as shown in *1 in FIG. 4, the fixing improvement mode (1) temperature is a higher temperature than the fixing improvement mode (2) temperature if the environment in which the printer 1 is placed is the same.

[0076] Next, the CPU 101 forcibly reduces the rotation speed of the main motor 108 to half speed and drives it in the forward direction (S131), and then executes image formation processing (S52). In S51 of the SX printing processing in Fig. 7, as described above, the rotation speed of the main motor 108 is determined based on the size and type of sheet S to be printed, other special settings, etc. In contrast, in S131, the rotation speed of the main motor 108 is determined to be half speed regardless of the size and type of sheet S to be printed, other special settings, etc.

[0077] Next, the CPU 101 executes a sheet reversing process (S132). Details of the sheet reversing process have been described with reference to Fig. 10, and therefore will not be described again here. When the sheet reversing process is executed, the sheet S is conveyed in the reverse direction from the switchback position D2 on the conveying path 201, passes through the re-conveying path 202, and is conveyed again from the junction position J to the conveying path 201.

[0078] Next, CPU 101 executes non-image formation processing (S133). The non-image formation processing is processing in which no image is formed on sheet S and sheet S is passed through fuser 6 at a temperature in fixing improvement mode (1). FIG. 14 shows detailed procedures for the non-image formation processing. In FIG. 14, the same steps as those in the image formation processing in FIG. 8(a) are assigned the same step numbers. The non-image formation processing in FIG. 14 is configured by omitting the image formation-related processing, i.e., the processing in S60 and S62, from the image formation processing in FIG. 8(a). When the non-image formation processing is executed, sheet S passes through fuser 6 without an image being formed, and is transported to a position where discharge sensor SE3 detects the trailing edge of sheet S (S63: YES).

[0079] 13, the CPU 101 executes the sheet discharge process (S53). The subsequent processes of S54 and S55 will not be described.

[0080] In this way, in the fixing improvement mode (1) SX printing process, the image on the sheet S is fixed to the sheet S at a fixing temperature that is even higher than the fixing temperature in the fixing improvement mode (2) printing process, and the sheet S passes through the fixing device 6 at half speed, so the fixing strength of the image on the sheet S can be made even higher than the fixing strength in the fixing improvement mode (2) printing process. In addition to this, the sheet S with an image formed on one side passes through the fixing device 6 twice, so the fixing strength of the image on the sheet S can be made even higher.

[0081] FIG. 15 shows the detailed procedure for the fixing improvement mode (1) DX printing process. In FIG. 15, the same steps as those in FIG. 9 are assigned the same step numbers, and the description of those steps will be omitted where appropriate. The fixing improvement mode (1) DX printing process in FIG. 15 differs from the DX printing process in FIG. 9 only in the steps S140 and S141. The steps S140 and S141 are the same as the steps S130 and S131 (see FIG. 13). That is, the fixing improvement mode (1) DX printing process differs from the DX printing process in that the sheet S with images formed on both sides is passed through the fuser 6, the fixing temperature of which is set to the fixing improvement mode (1) temperature, at half the conveying speed. The steps S72 to S77 after S141 were described in detail in the DX printing process in FIG. 9, so they will not be described again here.

[0082] In this way, in the fixing improvement mode (1) DX printing process, the image on the sheet S is fixed to the sheet S at a fixing temperature that is even higher than the fixing temperature in the fixing improvement mode (2) printing process, and the sheet S passes through the fixing device 6 at half speed, so the fixing force of the image on the sheet S can be made even higher than the fixing force in the fixing improvement mode (2) printing process.

[0083] (First Modification) Next, a modified example of the fixing improvement mode (1) DX printing process will be described. In the fixing improvement mode (1) DX printing process of Fig. 15, the sheet S with an image formed on its first side passes through the fixing device 6 twice, but the sheet S with an image formed on its second side passes through the fixing device 6 only once, so the fixing strength of the image on the second side of the sheet S is lower than the fixing strength of the image on the first side of the sheet S. Therefore, in this modified example, the sheet S with an image formed on its second side passes through the fixing device 6 again, thereby increasing the fixing strength of the image on the second side.

[0084] Fig. 16 shows the detailed procedure of a modified example of the DX printing process in the fixing improvement mode (1). In Fig. 16, the same steps as in Fig. 15 are given the same step numbers, and the description of those steps will be omitted as appropriate.

[0085] 15, S72 and S74 do not mention whether even-numbered pages or odd-numbered pages are to be printed on the first and second sides of sheet S. In contrast, in the modified example of the fixing improvement mode (1) DX printing process in Fig. 16, images of even-numbered pages included in the print job are formed on the first side of sheet S (S72'), and images of odd-numbered pages included in the print job are formed on the second side of sheet S (S74').

[0086] In the modified example of the fixing improvement mode (1) DX printing process in Fig. 16, a sheet reversal process (S142) and an image non-forming process (S143) are added to the fixing improvement mode (1) DX printing process in Fig. 15. As a result, the sheet S with images formed on both the first and second sides is passed through the fixing unit 6 again at half speed.

[0087] In this way, according to this modification, the fixing force of the image on the second surface of the sheet S can also be improved.

[0088] (Second Modification) Next, a modified example of the fixing improvement mode (1) SX printing process will be described. In the fixing improvement mode (1) SX printing process of Fig. 13, the sheet S on which an image has been formed is passed through the fixing unit 6 again via the re-conveyance path 202, so that when the sheet S is discharged to the discharge tray 22, the sheet S is placed on the discharge tray 22 with the side on which the image has been formed facing up. In other words, the sheet S is output face-up. Therefore, in this modified example, the sheet S is output face-down.

[0089] FIG. 17 shows the detailed procedure of a modified example of the fixing improvement mode (1) SX printing process. In FIG. 17, the same steps as those in FIG. 13 are given the same step numbers, and the description of those steps will be omitted where appropriate. The modified example of the fixing improvement mode (1) SX printing process in FIG. 17 differs from the fixing improvement mode (1) SX printing process in FIG. 13 in that a sheet reversal process (S150) and an image non-forming process (S151) are added. In this way, by passing the sheet S on which an image has been formed through the fixing device 6 three times, the sheet S on which the image has been formed is output face-up to the output tray 22.

[0090] (Third Modification) Next, another modified example of the fixing improvement mode (1) DX printing process will be described. In the modified example of the fixing improvement mode (1) DX printing process in Fig. 16, the sheet S on which an image has been formed passes through the fixing device 6 three times, and the sheet S on which an image has been formed is discharged to the discharge tray 22 with the odd-numbered page facing up. In other words, the sheet S is output face-up. Therefore, in this modified example, the sheet S is output face-down.

[0091] FIG. 18 shows the detailed procedure of another modified example of the fixing improvement mode (1) DX printing process. In FIG. 18, the same steps as those in FIG. 16 are given the same step numbers, and the description of those steps will be omitted as appropriate. The other modified example of the fixing improvement mode (1) DX printing process in FIG. 18 differs from the modified example of the fixing improvement mode (1) SX printing process in FIG. 16 in that a sheet reversal process (S160) and an image non-forming process (S161) are added. In this way, by passing the sheet S on which an image has been formed through the fixing device 6 four times, the sheet S on which the image has been formed is output face-down to the output tray 22.

[0092] (Fourth Modification) Next, another modified example of the fixing improvement mode (1) DX printing process will be described. In the modified example of the fixing improvement mode (1) DX printing process in Fig. 16, the sheet S on which an image has been formed passes through the fixing unit 6 three times, and therefore, as described above, the sheet S on which an image has been formed is output face-up. Therefore, in this modified example, even if the sheet S is output face-up, the order of the pages of the print job in which an image is formed on the first side of the sheet S and the pages of the print job in which an image is formed on the second side of the sheet S is changed so that the even-numbered pages are output to the output tray 22 as the obverse side.

[0093] FIG. 19 shows detailed steps of yet another modified example of the fixing improvement mode (1) DX printing process. In FIG. 19, the same steps as in FIG. 16 are given the same step numbers, and descriptions of those steps will be omitted where appropriate. The yet another modified example of the fixing improvement mode (1) DX printing process in FIG. 19 differs from the modified example of the fixing improvement mode (1) SX printing process in FIG. 16 in that images of odd-numbered pages of the print job are formed on the first side (S72″) and images of even-numbered pages of the print job are formed on the second side (S74″). By changing the order of pages on which images are formed in this way, even if the sheet S on which images have been formed passes through the fixing unit 6 three times, the sheet S is output to the discharge tray 22 with the even-numbered pages on the front side and the odd-numbered pages on the back side.

[0094] (Fifth Modification) In the printer 1 of this embodiment, the print result improvement function is configured via the user interface 102. Alternatively, the print result improvement function may be configured using the connected PC 200 via the communication interface 104. Specifically, the control program 103A may include a program that functions as a web server for an EWS (Embedded Web Server) when executed by the CPU 101. When an administrator of the printer 1 launches a browser on the PC and enters a specific URL for the EWS in the browser's URL input field, the browser can access the EWS. When accessed from the browser, the CPU 101 transmits screen data, such as web page data, for displaying a browser screen for configuring the printer 1, such as a screen equivalent to the configuration screen 102A, on a display (not shown) of the PC 200. In response to receiving a configuration operation via the browser screen, the CPU 101 proceeds with a setting change process, thereby configuring the print result improvement function.

[0095] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0096] (1) In the above embodiment, an example was described in which the processes shown in Figures 5 to 19 are executed by CPU 101. However, these processes may be executed not only by CPU 101 but also by ASIC or other logic integrated circuits, or these processes may be executed by a CPU, etc., ASIC, or other logic integrated circuits working together.

[0097] (2) In the above embodiment, the printer 10 is used as an example of the printing device. The printing device may be a multifunction device equipped with a FAXIF.

[0098] (3) In the above embodiment, the PC 200 is used as an example of the external device. The external device may be a mobile terminal such as a smartphone.

[0099] (4) In the above embodiment, the number of times that the sheet S on which an image is formed is passed through the fixing device 6 is a maximum of three times in the SX printing process and a maximum of four times in the DX printing process, but the sheet S on which an image is formed may be passed through the fixing device 6 a greater number of times.

[0100] (5) In the above embodiment, the setting information indicating the options selected on the driver setting screen 210 (see FIG. 3(a)) is stored in the memory of the PC 200, but is not stored in the memory 103 of the printer 1. However, this is not limiting, and the CPU 101 may receive the setting information indicating the options selected on the driver setting screen 210 from the PC 200 and store it in the memory 103 as setting information 103B. [Explanation of symbols]

[0101] 1...printer, 3...conveying section, 4...image forming section, 6...fixing unit, 63...heater, 102...user IF, 103...memory, 103A...control program, 103B...setting information, 104...communication IF, 108...main motor, 200...PC, S...sheet, SE1...pre-register sensor, SE2...post-register sensor, SE3...eject sensor.

Claims

1. a print engine capable of printing on a sheet by forming an image on the sheet using an electrophotographic method; a fixing unit located downstream of the print engine in a conveyance path of the sheet, the fixing unit fixing an image formed on the sheet by the print engine to the sheet; A controller; A printing device comprising: the printing device is capable of switching between a normal mode and a fixing enhancement mode; The controller When performing single-sided printing on the sheet using the print engine, When the printing device is in the normal mode, an image is formed on a first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, and the sheet that has passed through the fixing device is discharged; When the printing device is in the enhanced fixing mode, it is possible to control the printing device so that an image is formed on a first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, and the sheet that has passed through the fixing device passes through the fixing device again without forming an image on a second side of the sheet, and then is discharged. A printing device characterized by:

2. The controller When the printing device is in the enhanced fixing mode, It is possible to forcibly control the conveying speed of the sheet when the sheet having an image formed on the first side is passed through the fixing device, and the conveying speed of the sheet when the sheet having an image formed on the first side is further passed through the fixing device without forming an image on the second side, to be slow.

2. The printing device according to claim 1.

3. The controller When the printing device is in the enhanced fixing mode, It is possible to control the fixing temperature of the fixing unit when the sheet with an image formed on the first side is passed through the fixing unit, and the fixing temperature of the fixing unit when the sheet with an image formed on the first side is passed through the fixing unit again without forming an image on the second side, so as to be higher than the fixing temperature of the fixing unit when the printing device is in the normal mode.

3. The printing device according to claim 2.

4. the printing device is capable of double-sided printing on the sheet using the print engine; The controller When the printing device is in the enhanced fixing mode, When performing single-sided printing on the sheet, it is possible to control the sheet so that an image is formed on a first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, the sheet that has passed through the fixing device passes through a conveying path for double-sided printing and is guided to the fixing device without forming an image on a second side of the sheet, and the sheet that has been guided to the fixing device passes through the fixing device again before being discharged.

2. The printing device according to claim 1.

5. The controller When the printing device is in the enhanced fixing mode, When performing double-sided printing on the sheet, it is possible to control the sheet so that an image is formed on the first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, the sheet that has passed through the fixing device passes through the transport path for double-sided printing, an image is formed on the second side of the sheet, and the sheet is then guided to the fixing device, and the sheet that has been guided to the fixing device passes through the fixing device again before being discharged, controlling a conveying speed of the sheet when the sheet having the image formed on the first side passes through the fixing unit, and a conveying speed of the sheet when the sheet having the image formed on both the first side and the second side passes through the fixing unit, to be forcibly slow; It is possible to control the fixing temperature of the fixing unit when the sheet with an image formed on the first side is passed through the fixing unit, and the fixing temperature of the fixing unit when the sheet with images formed on the first side and the second side is further passed through the fixing unit, so as to be higher than the fixing temperature of the fixing unit when the printing device is in the normal mode.

5. The printing device according to claim 4.

6. The controller When the printing device is in the enhanced fixing mode, When performing double-sided printing on the sheet, it is possible to control the printing apparatus so that an image is formed on the first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, the sheet that has passed through the fixing device passes through a transport path for double-sided printing, an image is formed on the second side of the sheet, the sheet with images formed on the first and second sides passes through the fixing device, the sheet that has passed through the fixing device passes further through the transport path for double-sided printing, and is guided to the fixing device without forming an image again on the first side of the sheet, and the sheet that has been guided to the fixing device passes through the fixing device and is then discharged.

5. The printing device according to claim 4.

7. the printing device is capable of double-sided printing on the sheet using the print engine; The controller When the printing device is in the enhanced fixing mode, When performing single-sided printing on the sheet, it is possible to control the printing apparatus so that an image is formed on a first side of the sheet, the sheet with the image formed on the first side passes through the fixing device, the sheet that has passed through the fixing device passes through a transport path for double-sided printing and is guided to the fixing device without forming an image on the second side of the sheet, the sheet that has been guided to the fixing device passes through the fixing device, and then passes through the transport path for double-sided printing and is guided to the fixing device without forming an image again on the first side of the sheet, and the sheet that has been guided to the fixing device passes through the fixing device before being discharged.

2. The printing device according to claim 1.

8. The controller When the printing device is in the enhanced fixing mode, When performing double-sided printing on the sheet, it is possible to control the printing apparatus so that an image is formed on the first side of the sheet, the sheet with the image formed on the first side is passed through the fixing unit, the sheet that has passed through the fixing unit is passed through the transport path for double-sided printing, an image is formed on the second side of the sheet, the sheet with images formed on the first and second sides is passed through the fixing unit, the sheet that has passed through the fixing unit is further passed through the transport path for double-sided printing and is guided to the fixing unit without forming an image again on the first side of the sheet, the sheet that has been guided to the fixing unit is passed through the fixing unit and then further passed through the transport path for double-sided printing and is guided to the fixing unit without forming an image again on the second side of the sheet, and the sheet that has been guided to the fixing unit is passed through the fixing unit and then discharged.

5. The printing device according to claim 4.

9. The controller When the printing device is in the normal mode, When performing double-sided printing on the sheet, a first image is formed on the first side of the sheet, the sheet with the first image formed on the first side is passed through the fixing device, the sheet that has passed through the fixing device is passed through a conveying path for double-sided printing, a second image is formed on the second side of the sheet, and the sheet is then guided to the fixing device, and the sheet that has been guided to the fixing device is passed through the fixing device and then discharged, When the printing device is in the enhanced fixing mode, When performing double-sided printing on the sheet, it is possible to control the printing apparatus so that the second image is formed in the normal mode on the first side of the sheet, the sheet with the second image formed on the first side passes through the fixing unit, the sheet that has passed through the fixing unit passes through the transport path for double-sided printing, the first image is formed in the normal mode on the second side of the sheet, the sheet with the second image formed on the first side and the first image formed on the second side passes through the fixing unit, the sheet that has passed through the fixing unit passes further through the transport path for double-sided printing, and is guided to the fixing unit without forming an image again on the first side of the sheet, and the sheet that has been guided to the fixing unit passes through the fixing unit and is then discharged.

5. The printing device according to claim 4.

10. The controller The printing device is capable of being placed in a first enhanced fusing mode and a second enhanced fusing mode in accordance with the received instruction; When the printing device is in the first enhanced fusing mode, when performing single-sided printing on the sheet, an image is formed on a first side of the sheet, the sheet with the image formed on the first side is passed through the fixing device, and the sheet that has passed through the fixing device is passed through the fixing device again without forming an image on a second side of the sheet, and is then discharged, and at this time, a conveying speed of the sheet when the sheet with the image formed on the first side is passed through the fixing device and a conveying speed of the sheet when the sheet with the image formed on the first side is passed through the fixing device again without forming an image on its second side are forcibly reduced, and a fixing temperature of the fixing device when the sheet with the image formed on the first side is passed through the fixing device and a fixing temperature of the fixing device when the sheet with the image formed on the first side is passed through the fixing device again without forming an image on its second side are controlled to be higher than the fixing temperature of the fixing device when the printing device is in the normal mode, When the printing device is in the second enhanced fusing mode, When performing single-sided printing on the sheet, it is possible to form an image on a first side of the sheet, pass the sheet with the image formed on the first side through the fixing device, and discharge the sheet that has passed through the fixing device, and at this time, control the fixing temperature of the fixing device when the sheet with the image formed on the first side is passed through the fixing device to be higher than the fixing temperature of the fixing device when the printing device is in the normal mode.

2. The printing device according to claim 1.

11. The controller The printing device may be placed in a curl reduction mode in accordance with the received instruction, When the printing device is in the curl reduction mode, When performing single-sided printing on the sheet, it is possible to form an image on a first side of the sheet, pass the sheet with the image formed on the first side through the fixing device, and discharge the sheet that has passed through the fixing device, and at this time, control the fixing temperature of the fixing device when the sheet with the image formed on the first side is passed through the fixing device to be lower than the fixing temperature of the fixing device when the printing device is in the normal mode.

11. The printing device according to claim 10.

12. The printing device further comprises: communication interface, Equipped with The controller When performing single-sided printing on the sheet based on a print job received via the communication interface, The printing device is capable of being set to the first intensive fixing mode, the second intensive fixing mode, and the curl reduction mode in accordance with instructions from the print job.

12. The printing device according to claim 11.

13. The printing device further comprises: A user interface; Memory and Equipped with The controller In response to receiving an instruction via the user interface, information indicating the received instruction can be stored in the memory; The printing device is capable of being placed in the first intensive fixing mode, the second intensive fixing mode, and the curl reduction mode according to the information stored in the memory.

13. The printing device according to claim 12.

14. a print engine capable of printing on a sheet by forming an image on the sheet using an electrophotographic method; a fixing unit located downstream of the print engine in a conveyance path of the sheet, the fixing unit fixing an image formed on the sheet by the print engine to the sheet; A controller; A printing device comprising: The controller The printing device can be set to a normal mode, a first enhanced fusing mode, and a second enhanced fusing mode in accordance with the received instructions; forming an image on a first side of the sheet when performing single-sided printing on the sheet using the print engine; When the printing device is in the normal mode, the image formed on the first surface of the sheet is fixed by a first fixing method using the fixing device, and then the sheet is discharged outside the printing device; When the printing device is in the first enhanced fixing mode, the image formed on the first surface of the sheet is fixed by a second fixing method using the fixing device, which is a fixing method that provides stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device; When the printing device is in the second enhanced fixing mode, it is possible to control the printing device so that the image formed on the first surface of the sheet is fixed by a third fixing method using the fixing device, which is a fixing method that provides stronger fixing power than the first fixing method, and then the sheet is discharged outside the printing device. A printing device characterized by:

15. the printing device is capable of double-sided printing on the sheet using the print engine; the second fixing method includes a procedure of: guiding the sheet, on which an image is formed on the first side and which has passed through the fixing device, through a conveying path for double-sided printing to the fixing device without forming an image on the second side of the sheet; and further passing the sheet which has been guided to the fixing device through the fixing device; the first fixing method and the third fixing method do not include a procedure of: passing the sheet, which has an image formed on the first side and passed through the fixing device, through a conveying path for double-sided printing, to the fixing device without forming an image on the second side of the sheet; and further passing the sheet, which has been led to the fixing device, through the fixing device.

15. The printing device according to claim 14.

16. The controller The printing device may be placed in a curl reduction mode in accordance with the received instruction, When the printing device is in the curl reduction mode, it is possible to control the printing device to fix the image formed on the first side of the sheet by a fourth fixing method using the fixing device, which is a fixing method that uses a weaker fixing force than the first fixing method, and then discharge the sheet from the printing device.

16. The printing device according to claim 15.

17. The printing device further comprises: communication interface, Equipped with The controller When performing single-sided printing on the sheet based on a print job received via the communication interface, The printing device is capable of switching to the normal mode, the first intensive fixing mode, the second intensive fixing mode, and the curl reduction mode in accordance with instructions from the print job.

17. The printing device according to claim 16.

18. The printing device further comprises: A user interface; Memory and Equipped with The controller In response to receiving an instruction via the user interface, information indicating the received instruction can be stored in the memory; According to the information stored in the memory, the printing device can be set to the normal mode, the first intensive fixing mode, the second intensive fixing mode, and the curl reduction mode.

18. The printing device according to claim 17.

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