Image forming apparatus and image forming method

Abstract

Maintain high image quality while properly preheating the pressurized rotating body. [Solution] The system includes a first heating rotating body 61 that heats the toner image forming surface of a continuous recording medium R, a pressurizing rotating body 63 that pressurizes the recording medium toward the first heating rotating body, a second heating rotating body 62 that heats the pressurizing rotating body, and a pressurizing / separating means 64 that switches between a pressurized state and a separated state between the first heating rotating body and the pressurizing rotating body. The pressurizing / separating means brings the pressurizing rotating body and the second heating rotating body into contact when the first heating rotating body and the pressurizing rotating body are separated, and separates the pressurizing rotating body and the second heating rotating body when the first heating rotating body and the pressurizing rotating body are in a pressurized state.

Description

Technical Field

[0001] The present disclosure relates to an image forming apparatus and an image forming method.

Background Art

[0002] An electrophotographic image forming apparatus includes a fixing device that melts and pressure-bonds toner to fix it onto a recording medium. The fixing device includes a heating rotating body and a pressure rotating body for heating and pressing the recording medium. Since a rubber layer or the like is formed on the surface of the pressure rotating body, heat is less likely to be transmitted when the pressure rotating body is heated from the outside, and it takes time for the temperature to rise to a level that enables fixing.

[0003] FIG. 10 is a diagram in which the vertical axis represents the surface temperatures of the heating rotating body and the pressure rotating body that have started heating, and the horizontal axis represents elapsed time. Reference sign L1 indicates the change in surface temperature of the heating rotating body, and reference sign L2 indicates the change in surface temperature of the pressure rotating body. Note that FIG. 10 shows measurement results for a fixing device capable of switching between a pressure-bonded state and a separated state of the heating rotating body and the pressure rotating body. In FIG. 10, reference sign Tp is the target heating temperature for performing fixing, and reference sign ta indicates the timing at which pressure bonding of the heating rotating body and the pressure rotating body is started. As shown in FIG. 10, the heating rotating body starts heating in a rotationally driven state and quickly reaches the target temperature. When the heating rotating body is pressure-bonded to the rotationally driven pressure rotating body, the temperature temporarily drops sharply due to the temperature difference, and then quickly rises back to the original temperature. In contrast, when the pressure rotating body is pressure-bonded to the heating rotating body, the temperature rises slowly at a low speed.

[0004] As described above, since the pressurized rotating body heats up slowly, a method of preheating is employed in which the heating rotating body and the pressurized rotating body are pressed together while rotating, even when not forming an image. However, when the recording medium is roll paper, it is transported downstream by the rotating heating rotating body and the pressurized rotating body, resulting in wasted resources. On the other hand, if the bodies are pressed together while both are stopped rotating, there is a risk that the roll paper will be overheated and suffer thermal damage. Moreover, this also creates the problem that the entire outer circumference of the pressurized rotating body cannot be preheated.

[0005] Therefore, to address the above problem, the application of an external heating roller that preheats the pressurized rotating body separately from the heated rotating body is being considered (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2007-025540 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, the external heating roller had a problem in that scratches occurred on the surface of the pressurized rotating body due to sliding caused by a small speed difference between the roller and the pressurized rotating body. Furthermore, if scratches occur on the surface of the pressurized rotating body, it can cause unevenness in the recording medium, leading to inconsistent fixing and potentially degrading the image quality of the formed image. In particular, when the recording medium was film, it was susceptible to the effects of scratches on the surface of the pressurized rotating body, resulting in a significant decrease in image quality.

[0008] This disclosure aims to maintain high image quality while properly preheating the pressurized rotating body. [Means for solving the problem]

[0009] This disclosure relates to an image forming apparatus, A first heating rotating body that heats the toner image forming surface of a continuous recording medium, A pressurizing rotating body that pressurizes the recording medium toward the first heating rotating body, A second heating rotating body for heating the aforementioned pressurized rotating body, The system includes a pressurizing and separating means for switching between a pressurized state and a separated state between the first heating rotating body and the pressurizing rotating body, The aforementioned pressurizing and separating means is When the first heating rotating body and the pressurizing rotating body are separated, the pressurizing rotating body and the second heating rotating body are brought into contact. When the first heating rotating body and the pressurized rotating body are under pressure, the pressurized rotating body and the second heating rotating body are separated.

[0010] Furthermore, this disclosure relates to an image forming method, An image forming apparatus comprising a first heating rotating body for heating the toner image forming surface of a continuous recording medium, a pressurizing rotating body for pressurizing the recording medium toward the first heating rotating body, and a second heating rotating body for heating the pressurizing rotating body, wherein the first heating rotating body and the pressurizing rotating body can be switched between a pressurized state and a separated state, When the first heating rotating body and the pressurizing rotating body are separated, the pressurizing rotating body and the second heating rotating body are brought into contact. When the first heating rotating body and the pressurized rotating body are under pressure, the pressurized rotating body and the second heating rotating body are separated. [Effects of the Invention]

[0011] According to this disclosure, it is possible to maintain high image quality while properly preheating the pressurized rotating body. [Brief explanation of the drawing]

[0012] [Figure 1] This figure shows an example of the overall configuration of the image forming apparatus in the first embodiment. [Figure 2] This diagram shows the main components of the control system in the main unit of Figure 1. [Figure 3]It is a schematic diagram illustrating the configuration of the fixing unit in a standby state where no image formation is performed, viewed from the same direction as in FIG. 1. [Figure 4] It is a schematic diagram illustrating the configuration of the fixing unit in a state where fixing is performed during image formation, viewed from the same direction as in FIG. 1. [Figure 5] It is a flowchart showing operation control of the fixing unit. [Figure 6] It is a schematic diagram illustrating the configuration of the fixing unit according to the second embodiment in a standby state where no image formation is performed, viewed from the same direction as in FIG. 1. [Figure 7] It is a schematic diagram illustrating the configuration of the fixing unit according to the second embodiment in a state where fixing is performed during image formation, viewed from the same direction as in FIG. 1. [Figure 8] It is a schematic diagram illustrating the configuration of the fixing unit according to the third embodiment in a standby state where no image formation is performed, viewed from the same direction as in FIG. 1. [Figure 9] It is a schematic diagram illustrating the configuration of the fixing unit according to the third embodiment in a state where fixing is performed during image formation, viewed from the same direction as in FIG. 1. [Figure 10] It is a graph showing temporal changes in measured temperatures of a heating rotating body and a pressure rotating body in a conventional fixing device that can switch between a pressure-contact state and a separated state of the heating rotating body and the pressure rotating body. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0013] Hereinafter, the present embodiment will be described in detail with reference to the drawings. However, the scope of the disclosure is not limited to the illustrated examples.

[0014] [First Embodiment] FIG. 1 is a diagram showing an example of the overall configuration of an image forming apparatus 100 according to the first embodiment. FIG. 2 is a diagram showing the main part of a control system of the image forming apparatus 100 according to the first embodiment. The image forming apparatus 100 is an apparatus capable of forming an image on roll-shaped continuous paper (roll paper R), which is a continuous recording medium. The continuous recording medium refers to a recording medium that is sufficiently longer and continuous than the full length of the conveyance path, rather than a short recording medium such as sheet paper or cut paper. For convenience, we will refer to it as "roll paper," but this does not mean that it is limited to paper. Roll paper R as a continuous recording medium can be any thin sheet-like material, and includes film materials such as resin.

[0015] The image forming apparatus 100 is configured such that a paper feeding unit 1, a transport adjustment unit 2, a main unit 3, a transport adjustment unit 4, and a winding unit 5 are arranged from upstream along the transport direction of the roll paper R. The main unit 3 is configured for forming an image on the roll paper R. The paper feeding unit 1, transport adjustment unit 2, transport adjustment unit 4, and winding unit 5 are configured for supplying, transporting, and collecting the roll paper R from the main unit 3.

[0016] The paper feeding unit 1 is a device that feeds roll paper R to the main unit 3. The paper feeding unit 1 transports the roll paper R, which is wound around the support shaft X, to the main unit 3 at a constant speed via transport roller pairs such as a feed roller pair and a paper feeding roller pair. The paper feeding operation of the paper feeding unit 1 is controlled by the control unit 10 provided in the main unit 3.

[0017] The transport adjustment unit 2 transports the roll paper R, which is fed from the paper feeding unit 1 to the main unit 3 at a constant speed, with some slack. The transport adjustment unit 2 also has a function to supply the roll paper R to the main unit 3 in a way that does not create excessive tension.

[0018] The main unit 3 performs image formation using an intermediate transfer method that utilizes electrophotographic process technology. The configuration of the main unit 3 will be explained with reference to Figures 1 and 2. The main unit 3 includes a control unit 10, an image reading unit 20, an operation display unit 30, an image forming unit 40, a paper transport unit 50, a fixing unit 60, a storage unit 70, a communication unit 80, and the like.

[0019] The control unit 10 includes a CPU, ROM, RAM, etc. CPU stands for Central Processing Unit. ROM stands for Read Only Memory. RAM stands for Random Access Memory. The CPU reads a program from ROM according to the processing content and loads it into RAM. Then, the CPU works in cooperation with the loaded program to centrally control each component of the main unit 3, such as the paper feed unit 1, transport adjustment unit 2, transport adjustment unit 4, and winding unit 5. For example, the control unit 10 synchronously controls the paper feeding unit 1, the transport adjustment unit 2, the transport adjustment unit 4, and the winding unit 5 to control the transport operation of the roll paper R. Furthermore, the control unit 10 controls the main unit 3 based on image data acquired by the image reading unit 20 or the communication unit 80 from an external source to form an image on the roll paper R.

[0020] Furthermore, the control unit 10 realizes the functional configurations shown in Figure 2 by having the CPU execute the control program 71 in the memory unit 70. The control unit 10 functions, for example, as a heating control unit 11 and a drive control unit 12. These functional configurations will be described later.

[0021] The image reading unit 20 is comprised of an automatic document feeding unit 21, referred to as an ADF, and a document image scanning device 22, among other components. ADF is an abbreviation for Auto Document Feeder. The automatic document feeding unit 21 transports documents placed in the document tray T using a transport mechanism and sends them to the document image scanning device 22. The automatic document feeding unit 21 makes it possible to continuously scan images (including both sides) of multiple documents placed in the document tray T all at once. The document image scanning device 22 optically scans the document transported from the automatic document feeding unit 21 onto the contact glass or the document placed on the contact glass. The document image scanning device 22 then forms an image of the reflected light from the document onto the light-receiving surface of the CCD sensor and reads the document image. CCD is an abbreviation for Charge Coupled Device. The image reading unit 20 generates image data based on the reading results from the document image scanning device 22.

[0022] The operation display unit 30 is composed of a display such as an LCD or OLED with a touch panel. The operation display unit 30 functions as a display unit 31 and an operation unit 32. The display unit 31 displays various operation screens, image statuses, and the operating status of each function in accordance with the display control signals input from the control unit 10. The operation unit 32 is equipped with various operation keys such as a numeric keypad and a start key, and accepts various input operations from the user and outputs operation signals to the control unit 10. Note that the display unit 31 and the operation unit 32 do not have to be integrated as described above, but may be configured as separate and independent units.

[0023] The image forming unit 40 forms an image on the roll paper R based on image data acquired from an external device via the image reading unit 20 or the communication unit 80. In the following explanation, Y represents yellow, M represents magenta, C represents cyan, and K represents black. The same applies to Y, M, C, and K associated with numerical symbols.

[0024] The image forming unit 40 forms toner images of each color, Y, M, C, and K, on ​​the photoreceptor drums 41Y, 41M, 41C, and 41K, and then transfers them to the intermediate transfer belt 421. The image forming unit 40 then performs a secondary transfer of the four superimposed toner images on the intermediate transfer belt 421 onto the roll paper R fed from the paper feeding unit 1.

[0025] The fixing unit 60 fixes the toner image onto the roll paper R by heating and pressurizing the roll paper R on the fixing nip.

[0026] The paper transport unit 50 includes a transport path unit 52 equipped with multiple pairs of transport rollers, etc. The roll paper R, transported from the transport adjustment unit 2 to the main unit 3, is transported to the image forming unit 40 while tension is applied by the transport path unit 52. In the image forming unit 40, the toner image from the intermediate transfer belt 421 is transferred collectively to one side of the roll paper R. The toner image transferred to the roll paper R is then fixed in the fixing unit 60. The image-formed roll paper R is then transported to the winding unit 5 via the transport adjustment unit 4.

[0027] The memory unit 70 is composed of, for example, a non-volatile semiconductor memory such as flash memory or a hard disk drive. The memory unit 70 stores the input document data, various setting information, image data, and the like. Furthermore, the memory unit 70 stores a control program 71 for performing predetermined operation control in the image forming apparatus 100. Operation control based on the control program 71 will be described later.

[0028] The communication unit 80 is composed of, for example, a communication control card such as a LAN card. The communication unit 80 sends and receives various types of data to and from external devices such as personal computers via a communication network such as a LAN or WAN. LAN is an abbreviation for Local Area Network. WAN is an abbreviation for Wide Area Network.

[0029] The transport adjustment unit 4 transports the roll paper R, which has been discharged from the main unit 3, with some slack in order to feed it to the winding unit 5 at a constant speed. The transport adjustment unit 4 also has the function of supplying the roll paper R to the winding unit 5 in a way that does not create excessive tension.

[0030] The winding unit 5 is a device that winds up the roll paper R that has been transported from the main unit 3. The winding unit 5 winds the roll paper R transported from the main unit 3 onto the support shaft Y at a constant speed via a pair of transport rollers, such as a feed roller and a discharge roller. The winding operation of the winding unit 5 is controlled by the control unit 10 provided in the main unit 3.

[0031] [Fixing section] Here, the characteristic configuration of the fixing unit 60 described above will be explained in more detail using Figures 3 and 4. Figure 3 is a schematic diagram of the fixing unit 60 in a standby state when no image formation is taking place, viewed from the same direction as Figure 1. Figure 4 is a schematic diagram of the fixing unit 60 in a state where fixing is taking place during image formation, viewed from the same direction as Figure 1. The fixing unit 60 includes a first heating roller 61, a second heating roller 62, a pressure roller 63, and a pressure separation means 64.

[0032] The first heating roller 61 functions as a first heating rotating body that heats the toner image forming surface of the roll paper R. The first heating roller 61 is positioned near the upper side of the pressure roller 63, straddling the transport path of the roll paper R. The first heating roller 61 is supported by a rotary drive unit (not shown) so as to be rotatable around a rotation axis along a direction perpendicular to the transport direction of the roll paper R. The rotary drive unit includes a rotational drive source such as a motor and a transmission mechanism that transmits rotational motion to the first heating roller 61. The rotational drive source of the rotary drive unit is controlled by the control unit 10.

[0033] The first heating roller 61, for example, has a resin layer made of a fluorine compound such as PFA or PTFE with release properties formed on the outer surface of a cylindrical core. PFA is an abbreviation for perfluoroalkoxyalkane, and PTFE is an abbreviation for polytetrafluoroethylene. The first heating roller 61 has multiple heating sources 611, such as halogen heaters, built into it at various positions in the axial direction of the first heating roller 61. Furthermore, a temperature sensor 612 for detecting the temperature of the outer circumference of the first heating roller 61 is provided near the outer circumference of the first heating roller 61. The temperature sensor 612 is not limited to a specific type, such as a thermocouple or infrared sensor, but a non-contact type is preferred. The temperature sensor 612 outputs the detected temperature to the control unit 10. The control unit 10 controls the heating of the heating source 611 so that the detected temperature reaches the target temperature.

[0034] The pressure roller 63 functions as a rotating pressure body that pressurizes the roll paper R toward the first heating roller 61. The pressure roller 63 is positioned near the lower side of the first heating roller 61, across the transport path of the roll paper R. The pressure roller 63 is supported by the pressure separation means 64 so as to be rotatable around a rotation axis parallel to the rotation axis of the first heating roller 61.

[0035] Furthermore, the pressure roller 63 is supported by a pressure-separating means 64 so as to be switchable between a pressurized state and a separated state relative to the first heating roller 61. When the pressure roller 63 is in the pressurized state relative to the first heating roller 61, it can contact the roller 63 with a constant pressure and form a nip. The roll paper R is conveyed so as to pass through this nip, and the toner image is fixed by pressurized heating. The pressure roller 63 is equipped with a rotational drive unit (not shown) that rotates the pressure roller 63 via a transmission mechanism. The rotary drive unit includes a rotational drive source such as a motor and a transmission mechanism that transmits rotational motion to the pressure roller 63. The rotational drive source of the rotary drive unit is controlled by the control unit 10. The pressure roller 63 is rotated by a rotational drive source independent of the first heating roller 61.

[0036] The pressure roller 63, for example, has an elastic layer made of silicone rubber or the like formed on the outer surface of a cylindrical core. The elastic layer allows the pressure roller 63 to apply uniform pressure to the nip portion over the entire width in the rotational axis direction. In addition, a resin layer made of a fluorine compound such as PFA or PTFE, which has mold release properties, is formed on the outer surface of the elastic layer. A temperature sensor 632 is also installed near the outer circumference of the pressure roller 63 to detect the temperature of the outer circumference of the pressure roller 63. The temperature sensor 632 is of the same type as the temperature sensor 612 mentioned above. The temperature sensor 632 also outputs the detected temperature to the control unit 10. The control unit 10 controls the heating of the heating source of the second heating roller 62 when the second heating roller 62, which will be described later, is in contact with the pressure roller 63. In this case, the control unit 10 controls the heating of the heating source of the second heating roller 62 so that the temperature detected by the temperature sensor 632 reaches the target temperature.

[0037] The pressurized separation means 64 includes a support frame 641 and a switching section 642. The support frame 641 is a frame that rotatably supports the pressure roller 63. The support frame 641 is pivotably supported within the main body 3 by a support shaft 641a parallel to the rotation axis of the pressure roller 63. The support shaft 641a is positioned on one side of the pressure roller 63 in the direction of conveying the roll paper R. As a result, when the support frame 641 pivots, the pressure roller 63 can be raised and lowered. As shown in Figure 3, the pressure roller 63 moves away from the first heating roller 61 when it descends. Also, as shown in Figure 4, the pressure roller 63 comes into contact with the first heating roller 61 when it rises.

[0038] The switching unit 642 imparts a swinging motion to the support frame 641. The switching unit 642 includes an eccentric cam 643 and a rotation drive unit (not shown) that rotates the eccentric cam 643. The eccentric cam 643 is a circular outer circumference cam, the outer circumference of which abuts against the bottom of the pivot end side of the support frame 641. The eccentric cam 643 has a pivot axis 644 parallel to the support axis 641a of the support frame 641, at a position eccentric from the center of the outer circumference. Therefore, when the eccentric cam 643 rotates, a pivoting motion can be imparted to the support frame 641. The pivot shaft 644 receives rotational motion input from the rotation drive unit. The rotation drive unit consists of a rotation drive source, such as a motor, and a transmission mechanism that transmits its output to the pivot shaft 644. The rotation drive source is controlled by the control unit 10.

[0039] The second heating roller 62 is capable of contacting the pressure roller 63 and functions as a second heating rotating body that heats the pressure roller 63. The second heating roller 62 is located on the opposite side of the pressure roller 63 from the first heating roller 61. The second heating roller 62 is supported by a support bracket 621 so as to be rotatable around an axis of rotation parallel to the axis of rotation of the pressure roller 63. The bracket 621 is fixedly supported within the main body 3. Therefore, unlike the pressure roller 63 which moves up and down, the second heating roller 62 is held in a fixed position.

[0040] Unlike the first heating roller 61, the second heating roller 62 does not have a direct drive source to rotate it. When in contact with the pressure roller 63, the second heating roller 62 rotates in a manner driven by the pressure roller 63.

[0041] The second heating roller 62 has, for example, a resin layer made of a fluorine compound such as PFA or PTFE with release properties formed on the outer surface of a cylindrical core. The second heating roller 62 does not have an elastic layer like the pressure roller 63. The second heating roller 62 also has a heating source, such as a halogen heater (not shown), built into it at multiple positions in the axial direction of the second heating roller 62.

[0042] The first heating roller 61 and the second heating roller 62 are located on either side of the pressure roller 63. As mentioned above, the rotation axes of each roller 61 to 63 are parallel. The directions in which the first heating roller 61 and the second heating roller 62 are positioned relative to the pressure roller 63 are one perpendicular to the rotation axis and the other perpendicular to the pressure roller 63. In the examples of Figures 3 and 4, the first heating roller 61 and the second heating roller 62 are arranged so as to sandwich the pressure roller 63 in the vertical direction of the paper. With the above arrangement, the second heating roller 62 comes into contact with the pressure roller 63, which is spaced apart from the first heating roller 61, as shown in Figure 3. Furthermore, as shown in Figure 4, the second heating roller 62 is separated from the pressurized pressure roller 63 relative to the first heating roller 61. These state changes are performed by the pressurizing separation means 64 under the control of the control unit 10.

[0043] [Operation control of the fixing unit] The characteristic operation control centered on the fixing unit 60 of the above configuration will be explained based on the flowchart in Figure 5. This operation control is realized by the CPU of the control unit 10 executing the control program 71. Furthermore, this operation control realizes a suitable image forming method for the image forming apparatus 100. Here, we will explain using the example of when the above operation control is performed when the image forming apparatus 100 is started up. Note that the above operation control may be performed not only at startup but also at non-image forming times, such as between print jobs.

[0044] When the image forming apparatus 100 is started up, the control unit 10 starts heating the first heating roller 61 and the second heating roller 62 using the heating source 611, etc. (S1).

[0045] When the image forming apparatus 100 is started up, it is in a standby state where no image forming has yet taken place. In standby mode, the heating control unit 11 controls the rotation drive source of the switching unit 642 so that the pressure roller 63 is separated from the first heating roller 61. Consequently, the pressure roller 63 comes into contact with the second heating roller 62 (Figure 3). At this time, the drive control unit 12 controls the rotational drive source to rotate the pressure roller 63 at a lower speed than during image formation. The second heating roller 62 rotates in accordance with the low-speed rotation of the pressure roller 63 (S3).

[0046] While the pressure roller 63 is being preheated by the second heating roller 62, the control unit 10 monitors for the occurrence of a print job (S5). A print job occurs when the image reading unit 20 or the communication unit 80 acquires image data from an external source.

[0047] The control unit 10 maintains the preheated state of the pressure roller 63 when no print jobs are occurring. When a print job occurs, the heating control unit 11 controls the pressure roller 63 to pressurize the first heating roller 61. Specifically, the heating control unit 11 controls the rotation drive source of the switching unit 642. As a result, the pressure roller 63 moves away from the second heating roller 62 (Figure 4). At this time, the drive control unit 12 controls the rotational drive source to rotate the pressure roller 63 at the speed during image formation, that is, at a higher speed than during standby (S7). As a result, the roll paper R is conveyed while being fixed by heating and pressing at the nip portion of the pressure roller 63 and the first heating roller 61.

[0048] Next, while the roll paper R is being fixed by heating and pressurizing, the control unit 10 monitors the completion of the print job (S9). As long as the printing job is ongoing, the heat and pressure fixing process on the roll paper R continues.

[0049] On the other hand, when the print job is completed, the control unit 10 returns to processing S3. As a result, the pressure roller 63 returns to a state where it is separated from the first heating roller 61 and in contact with the second heating roller 62 (Figure 3). Then, until a new print job arises, the pressure roller 63 rotates at a low speed, and the second heating roller 62 preheats the pressure roller 63. The operation control of the fixing unit described above is performed continuously, for example, until the main power supply of the image forming apparatus 100 is turned off.

[0050] [Technical effects of the first embodiment] As described above, the image forming apparatus 100 has a pressure-relieving means 64 that switches between applying pressure to the first heating roller 61 and the pressure roller 63 and separating them. Then, the pressurizing separation means 64 separates the pressurizing roller 63 from the second heating roller 62 while under pressure with the first heating roller 61. Furthermore, the pressurizing separation means 64 causes the pressurizing roller 63 to be in contact with the second heating roller 62 while separated from the first heating roller 61. Therefore, when preheating is performed with the second heating roller 62, the pressure roller 63 separates from the first heating roller 61, and the roll paper R is not transported. Also, during fixing, the second heating roller 62 separates from the pressure roller 63, which reduces damage to the pressure roller 63 compared to when they are always in contact. Therefore, the image forming apparatus 100 can perform image formation quickly by preheating the pressure roller 63. Furthermore, the image forming apparatus 100 can reduce resource waste because the roll paper R is not transported during preheating. Furthermore, the image forming apparatus 100 reduces damage to the pressure roller 63, achieves good fixation, and maintains high image quality. In particular, even when the roll paper R is a film material, the image forming apparatus 100 can suitably form images with high image quality.

[0051] Furthermore, the image forming apparatus 100 has a heating control unit 11 that controls the pressurizing and separating means 64 during image forming and standby. Therefore, the image forming apparatus 100 can switch between preheating and fixing the pressure roller 63 at the appropriate time and opportunity. As a result, the image forming apparatus 100 can perform image formation quickly and maintain high image quality stably.

[0052] Furthermore, the image forming apparatus 100 has an image forming unit 40 that forms a toner image on a roll of paper R, and a fixing unit 60 quickly and effectively fixes the toner image on the roll of paper R. Therefore, the image forming apparatus 100 can reduce resource waste and perform image formation quickly with high image quality.

[0053] In addition, in the image forming apparatus 100, the second heating roller 62 rotates in accordance with the pressure roller 63. In theory, if the second heating roller 62 and the pressure roller 63 are driven to rotate in synchronous motion so that their outer peripheral speeds are perfectly matched, the occurrence of scratches can be reduced. However, both the second heating roller 62 and the pressure roller 63 expand and contract due to temperature changes, making complete synchronous rotation difficult. Therefore, by using driven rotation for the second heating roller 62 and the pressure roller 63, damage to the pressure roller 63 can be reduced compared to when the second heating roller 62 and the pressure roller 63 are individually driven to rotate. Consequently, the image forming apparatus 100 can perform image forming with higher image quality.

[0054] Furthermore, the image forming apparatus 100 has a drive control unit 12 that controls the rotation drive unit of the pressure roller 63. The drive control unit 12 sets the rotation speed of the pressure roller 63 to a lower speed than during image formation when the second heating roller 62 is in contact with the pressure roller 63. The rotation speed of the pressure roller 63 during image formation directly affects the processing time for image formation, so high-speed rotation is required. However, if the pressure roller 63 and the second heating roller 62 are preheated at high speed, the pressure roller 63 is prone to scratches, and reducing these scratches becomes difficult. Therefore, the above control by the drive control unit 12 makes it possible to reduce damage to the pressure roller 63 during preheating while performing high-speed image formation. As a result, the image forming apparatus 100 can perform image formation at high speed while producing higher image quality.

[0055] Furthermore, the outer surface of the second heating roller 62 has release properties. In particular, release properties are achieved by incorporating a fluorine compound into the outer surface of the second heating roller 62. The pressure roller 63 applies pressure to the side of the roll paper R that is not the surface on which the toner image is formed, so there is little opportunity for toner to adhere to it. Even in this case, there is a risk that dust, dirt, and other contaminants attached to the back surface of the roll paper R may adhere to the pressure roller 63. Even in such cases, the release properties of the outer surface of the second heating roller 62 reduce and suppress the adhesion of deposits from the pressure roller 63. Therefore, the occurrence of scratches on the pressure roller 63 caused by deposits on the second heating roller 62 is suppressed. As a result, the image forming apparatus 100 can perform image forming with higher image quality.

[0056] Furthermore, since the second heating roller 62 does not have an elastic layer on its outer circumference, heat is well conducted to the pressure roller 63. Therefore, the second heating roller 62 can quickly raise the temperature of the pressure roller 63 and maintain an appropriate temperature.

[0057] Furthermore, the fixing unit 60 has the following characteristic arrangement of the first heating roller 61, the pressure roller 63, and the second heating roller 62. Specifically, when the pressure roller 63 moves away from the first heating roller 61, it contacts the second heating roller 62. Also, when the first heating roller 61 is pressurized, the pressure roller 63 moves away from the second heating roller 62. This arrangement allows for proper switching between the movement and separation of the first heating roller 61 and the second heating roller 62 by moving only the pressure roller 63. Consequently, the fixing unit 60 can be implemented with a simple configuration, and their operation and control can be simplified.

[0058] [Second Embodiment] A second embodiment of the present disclosure, the fuser unit 60A, will now be described. For the fuser unit 60A, the same reference numerals are used for components identical to those of the fuser unit 60 described above, and redundant explanations are omitted. Furthermore, the fuser unit 60A, like the fuser unit 60, can be incorporated into the image forming apparatus 100 to fix the toner image on the roll paper R. Figure 6 is a schematic diagram of the fixing unit 60A in a standby state when no image formation is taking place, viewed from the same direction as in Figure 1. Figure 7 is a schematic diagram of the fixing unit 60A in a state where fixing is taking place during image formation, viewed from the same direction as in Figure 1.

[0059] The aforementioned fixing unit 60 exemplifies a first heating roller 61 as the first heating rotating body. However, the first heating rotating body is not limited to a roller. The fixing unit 60A has a configuration that includes an endless annular fixing belt 66A as the first heating rotating body.

[0060] The fixing unit 60A has a heating roller 61A and an upper pressure roller 65A positioned above the pressure roller 63, with the transport path of the roll paper R in between. The rotation axes of both the heating roller 61A and the upper pressure roller 65A are parallel to the rotation axis of the pressure roller 63. A fixing belt 66A is stretched between the heating roller 61A and the upper pressure roller 65A.

[0061] The fixing belt 66A, for example, has a base made of polyimide, on which an elastic layer made of silicone rubber or the like and a surface layer made of PFA, PTFE or the like are sequentially laminated. The heating roller 61A has almost the same configuration as the first heating roller 61 described above. The upper pressure roller 65A has almost the same configuration as the pressure roller 63 mentioned above.

[0062] When in standby mode, the pressure roller 63 is separated somewhat from the upper pressure roller 65A and the lower end of the fixing belt 66A by the pressure separation means 64. In this separated state, the pressure roller 63 is in contact with the second heating roller 62 (Figure 6). Furthermore, as shown in Figure 7, during image formation, the pressure roller 63 applies pressure to the upper pressure roller 65A and the fixing belt 66A via the roll paper R by the pressure separation means 64. In this pressurized state, the pressure roller 63 is separated from the second heating roller 62 (Figure 7). Furthermore, the control of the fixing unit 60A by the control unit 10 is performed in the same manner as the control of the fixing unit 60.

[0063] The fixing unit 60A, which has a fixing belt 66A, functions in the same way as the fixing unit 60 and can provide the same technical effects to the image forming apparatus 100 as the fixing unit 60.

[0064] Furthermore, the pressurizing rotating body is not limited to the pressurizing roller 63, but can also be configured with an endless annular pressurizing belt. In this case, a pressurizing belt with the same configuration as the fixing belt 66A is stretched over the two pressurizing rollers. In this configuration, the two pressure rollers and the pressure belt may be supported by the support frame 641, allowing the entire system to move up and down. Alternatively, only one of the pressure rollers and the pressure belt may be supported by the support frame 641. In that case, one of the pressure rollers and one end of the pressure belt move up and down to switch between the aforementioned pressurized state and the aforementioned separated state.

[0065] [Third Embodiment] A third embodiment of the present disclosure, the fuser unit 60B, will now be described. For the fuser unit 60B, the same reference numerals are used for components identical to those of the fuser unit 60 described above, and redundant explanations are omitted. Furthermore, the fuser unit 60B, like the fuser unit 60, can be incorporated into the image forming apparatus 100 to fix the toner image on the roll paper R. Figure 8 is a schematic diagram of the fixing unit 60B in a standby state when no image formation is taking place, viewed from the same direction as in Figure 1. Figure 9 is a schematic diagram of the fixing unit 60B in a state where fixing is taking place during image formation, viewed from the same direction as in Figure 1.

[0066] In the fixing section 60, an example was shown in which the pressure roller 63 is positioned such that when it separates from the first heating roller 61, it contacts the second heating roller 62. As a result, in the fixing section 60, the second heating roller 62 is fixed in place and does not move. However, the second heating roller 62 may also be supported in a way that allows it to move.

[0067] For example, the pressurizing separation means of the fixing section 60B includes a first switching section that supports the pressure roller 63 and a second switching section 620B that supports the second heating roller 62. The first switching unit described above has the same configuration as the pressurizing separation means 64 described above. The second switching unit 620B then switches between a separated state and a contact state between the pressure roller 63 and the second heating roller 62.

[0068] The second switching unit 620B includes a support bracket 621B for the second heating roller 62 and a rotation drive source 622B for rotating the support bracket 621B. The support bracket 621B rotatably supports the second heating roller 62 at its rotating end. The support bracket 621B is positioned so that the second heating roller 62 makes contact with and separates from the pressure roller 63 as it rotates. Preferably, the contact and separation of the second heating roller 62 by the support bracket 621B is performed along the radial direction of the pressure roller 63.

[0069] The rotation drive source 622B supports the base end of the support bracket 621B and provides the rotational motion described above. The rotation drive source 622B consists of, for example, a motor and a transmission mechanism. The motor of the rotation drive source 622B is controlled by the control unit 10.

[0070] The control unit 10 controls the fixing unit 60B in the same way as the control unit 60. However, the operation of the second switching unit 620B is performed in conjunction with the operation of the pressurizing separation means 64. In other words, during standby, the pressurizing separation means 64 separates the pressurizing roller 63 from the first heating roller 61. After this separation operation stops, the second switching unit 620B brings the second heating roller 62 into contact with the pressurizing roller 63 (Figure 8). Furthermore, during image formation, the pressure-separating means 64 pressurizes the pressure roller 63 against the first heating roller 61. Before the start of this pressurizing operation, the second switching unit 620B separates the second heating roller 62 from the pressure roller 63 (Figure 9). These actions reduce friction between the second heating roller 62 and the pressure roller 63, thereby reducing damage to the pressure roller 63.

[0071] Thus, the fixing unit 60B, which has a first switching unit and a second switching unit 620B, functions in the same way as the fixing unit 60. Therefore, the fixing unit 60B can provide the image forming apparatus 100 with the same technical effects as the fixing unit 60. Furthermore, since the second heating roller 62 is movable in the second switching section 620B, the degree of freedom in positioning the second heating roller 62 relative to the pressure roller 63 can be increased.

[0072] [others] The embodiments of this disclosure have been described above. However, this disclosure is not limited to the embodiments described above. For example, in the embodiments, a component formed integrally from a single member may be replaced with a component divided into multiple members that are connected or fixed to each other. Also, a component formed by connecting multiple members may be replaced with a component formed integrally from a single member. Furthermore, details shown in the embodiments can be modified as appropriate without departing from the spirit of the disclosure.

[0073] For example, the paper feeding unit 1, transport adjustment unit 2, main unit 3, transport adjustment unit 4, and winding unit 5 may each have their own control unit. In that case, each control unit may communicate with each other to coordinate and control the operation of each device. Alternatively, one of the control units may centrally control the operation of each device through the other control units.

[0074] Furthermore, while the fixing section of each of the above embodiments is exemplified as having a pressurizing rotating body that pressurizes and separates from the first heating rotating body, it is not limited to this configuration. For example, the first heating rotating body may be configured to pressurize and separate from the pressurizing rotating body. However, in that case, the second heating rotating body must be configured to make contact with and separate from the pressurized rotating body, as described in the second switching unit 620B above. [Explanation of symbols]

[0075] 3. Main body 10 Control Unit 11 Heating control unit 12 Drive control unit 40 Image forming unit 60, 60A, 60B Fixing section 61 First heating roller (first heating rotating body) 61A Heating Roller 611 Heating source 612 Temperature Sensor 62. Second heating roller (second heating rotating body) 620B Second switching section 621 Bracket 63 Pressure Roller 632 Temperature Sensor 64 Pressurized separation means 641 Support frame 641a Spindle 642 Switching section 643 Eccentric Cam 644 Rotary shaft 65A Upper pressure roller 66A Fixing belt 70 Memory section 71 Control Program 80 Communications Department 100 Image forming apparatus R Roll paper (continuous recording medium)

Claims

1. A first heating rotating body that heats the toner image forming surface of a continuous recording medium, A pressurizing rotating body that pressurizes the recording medium toward the first heating rotating body, A second heating rotating body for heating the aforementioned pressurized rotating body, The system includes a pressurizing and separating means for switching between a pressurized state and a separated state between the first heating rotating body and the pressurizing rotating body, The aforementioned pressurizing and separating means is When the first heating rotating body and the pressurizing rotating body are separated, the pressurizing rotating body and the second heating rotating body are brought into contact. When the first heating rotating body and the pressurizing rotating body are under pressure, the pressurizing rotating body and the second heating rotating body are separated. Image forming apparatus.

2. During image formation, The pressurizing and separating means is controlled such that the first heating rotating body and the pressurizing rotating body are in a pressurized state, and the pressurizing rotating body and the second heating rotating body are in a separated state. While waiting, The heating control unit controls the pressurizing and separating means so that the first heating rotating body and the pressurizing rotating body are separated, and the pressurizing rotating body and the second heating rotating body are in contact. The image forming apparatus according to claim 1.

3. The recording medium has an image forming unit that forms a toner image. The image forming apparatus according to claim 1.

4. The second heating rotating body rotates in accordance with the pressurized rotating body. The image forming apparatus according to claim 1.

5. The outer surface of the second heating rotating body has release properties. The image forming apparatus according to claim 1.

6. The outer surface of the second heating rotating body contains a fluorine compound. The image forming apparatus according to claim 5.

7. The second heating rotating body does not have an elastic layer on its outer circumference. The image forming apparatus according to claim 1.

8. The drive control unit controls the rotation drive unit of the pressurizing rotating body so that when the second heating rotating body is in contact with the pressurizing rotating body, the rotation speed of the pressurizing rotating body is lower than that during image formation. The image forming apparatus according to claim 2.

9. The aforementioned pressurizing and separating means is A first switching unit that switches between a separated state and a pressurized state of the first heating rotating body and the pressurizing rotating body, The system includes a second switching unit that switches between a separated state and a contact state between the pressurized rotating body and the second heated rotating body. The image forming apparatus according to claim 1.

10. The first heating rotating body, the pressurizing rotating body, and the second heating rotating body are, When the pressurizing rotating body separates from the first heating rotating body, the pressurizing rotating body comes into contact with the second heating rotating body. The arrangement is such that when the pressurizing rotating body pressurizes the first heating rotating body, the pressurizing rotating body separates from the second heating rotating body. The image forming apparatus according to claim 1.

11. An image forming apparatus comprising a first heating rotating body for heating the toner image forming surface of a continuous recording medium, a pressurizing rotating body for pressurizing the recording medium toward the first heating rotating body, and a second heating rotating body for heating the pressurizing rotating body, wherein the first heating rotating body and the pressurizing rotating body can be switched between a pressurized state and a separated state, When the first heating rotating body and the pressurizing rotating body are separated, the pressurizing rotating body and the second heating rotating body are brought into contact. When the first heating rotating body and the pressurizing rotating body are under pressure, the pressurizing rotating body and the second heating rotating body are separated. Image forming method.

Images