JP6911525B2 - Image forming apparatus and control method of image forming apparatus - Google Patents

Description

The present disclosure relates to an electrophotographic image forming apparatus.

In general, an image forming apparatus (printer, copier, facsimile, etc.) using electrophotographic process technology produces an electrostatic latent image by irradiating (exposing) a laser beam based on image data on a charged photoconductor. Form. Then, by supplying toner from the developing device to the photoconductor on which the electrostatic latent image is formed, the electrostatic latent image is visualized and the toner image is formed. Further, after the toner image is directly or indirectly transferred to the paper, the toner image is formed on the paper by heating and pressurizing with the fixing nip to fix the toner image.

The fixing device for fixing the toner image in this way is formed by a fixing surface side member such as a fixing roller or a fixing belt and a back surface side supporting member such as a pressure roller or a pressure belt which is pressed against the fixing surface side member. There is a heat-fixing type fixing device that heats and pressurizes while passing the paper on which the toner image is transferred through the fixing nip.

However, when paper having an embossed surface (hereinafter, also referred to as embossed paper), which is in high demand for printing guides, invitations, catalogs, pamphlets, etc., is passed through, the rubber layer of the fixing roller becomes uneven on the surface due to the embossing. May not follow. In that case, the surface of the fixing roller cannot be directly contacted and heated with the surface of the concave groove portion of the embossed paper, and the fixability of the toner transferred to the groove portion is lowered. As a result, image defects due to a decrease in the density of the groove, and a large amount of toner that cannot be fixed are offset to the fixing roller, which cannot be removed by the cleaning web, contaminating the next recording material, or contaminating the fixing device itself. Problems such as

In this respect, Patent Document 1 proposes a method of improving the followability of the rubber layer by increasing the thickness of the elastic layer of the fixing roller.

However, if the elastic layer of the fixing roller is made thicker in order to improve the followability of the concave groove portion, the thermal responsiveness from the internal halogen heater is deteriorated accordingly. Therefore, the fixability of plain paper in a low temperature environment during continuous paper passing deteriorates.

In addition, in order to keep the surface temperature of the fixing roller constant, it is necessary to set the temperature of the internal halogen heater higher by the thickening of the elastic layer, which reduces energy efficiency and reduces the adhesive surface between the core metal and the elastic layer. There is a problem that the temperature rises rapidly and the elastic layer is easily peeled off from the core metal.

In this regard, in Patent Document 2, as preheating, unprinted paper is passed through the fixing device. Then, a method has been proposed in which the printing device is passed through the fixing device again after printing.

Japanese Unexamined Patent Publication No. 2015-148760 Japanese Unexamined Patent Publication No. 2006-309061

However, even in this method, since the heating member does not come into contact with the concave groove portion of the embossed paper, a sufficient heat transfer effect cannot be obtained, and an offset may still occur in the concave groove portion.

The present disclosure is for solving the above-mentioned problems, and an object thereof is an image forming apparatus capable of improving fixability while suppressing a decrease in energy efficiency when fixing a toner image on embossed paper. And to provide a method of controlling an image forming apparatus.

An image forming apparatus according to a certain aspect includes a fixing member for fixing the toner carried on the paper to be passed, and a pressurizing member for forming a nip between the fixing members. The fixing member does not have an elastic layer or an elastic layer having a thickness of 180 μm or less, and the surface hardness of the fixing member is larger than the surface hardness of the pressure member. The image forming apparatus passes the paper having the embossed surface on which the toner is carried to the nip, and then reverses the front and back of the embossed surface to re-pass the paper to the nip. It is further provided with a control unit for transporting paper in the re-passage route.

Preferably, the pressure member has an elastic layer having a thickness of 4.2 mm or more.
Preferably, the surface hardness of the pressure member is set to 54 ° or less as measured by an Asker C hardness tester when a load of 9.6 N is applied.

Preferably, the contact force that abuts the fixing member and the pressurizing member is set to 200 N or more.
Preferably, the contact force that abuts the fixing member and the pressurizing member is set to 475 N or less.

Preferably, the peak pressure due to the contact between the fixing member and the pressurizing member is set to 50 kPa or more.

Preferably, the peak pressure due to the contact between the fixing member and the pressurizing member is set to 110 kPa or less.

Preferably, the control unit sets the time to pass through the nip formed by the fixing member and the pressurizing member to 40 msec or more.

Preferably, the control unit sets the time to pass through the nip formed by the fixing member and the pressurizing member to 90 msec or less.

Preferably, when re-passing the paper through the nip, the control unit conveys the paper at a speed slower than the speed at which the paper is first passed through the nip.

Preferably, the control unit conveys the paper to the nip when the temperature of the pressurizing member becomes equal to or higher than a predetermined temperature.

Preferably, the control unit conveys the paper to the nip after the fixing member has idled for a predetermined period of time.

A method of controlling an image forming apparatus according to a certain aspect includes image forming including a fixing member for fixing the toner carried on the paper to be passed and a pressure member for forming a nip between the fixing members. In the control method of the device, the fixing member does not have an elastic layer or an elastic layer having a thickness of 180 μm or less, and the surface hardness of the fixing member is larger than the surface hardness of the pressure member. The control method includes a step of passing paper having an embossed surface on which toner is supported on the nip, and a step of reversing the front and back of the embossed surface and re-passing the paper on the nip.

The above and other objectives, features, aspects and advantages of the present invention will become apparent from the following detailed description of the present invention as understood in connection with the accompanying drawings.

The image forming apparatus and the control method thereof of the present invention can improve the fixing property while suppressing a decrease in energy efficiency when fixing the toner image on the embossed paper.

It is a figure which shows schematic the whole structure of the image forming apparatus 1 based on embodiment. It is a figure explaining the main part of the control system of the image forming apparatus 1 based on an embodiment. It is a figure which outlines the structure of the fixing part 60 based on an embodiment. It is a flow figure explaining the process of forming a toner image based on an embodiment. It is a figure explaining the fixing process of the paper S having an embossed surface based on an embodiment. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 1. FIG. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 2. FIG. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 3. FIG. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 4. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 5. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 6. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 7. It is a figure explaining the evaluation result of the fixing process of the embossed paper based on Example 8.

Hereinafter, each embodiment will be described with reference to the drawings. In the following description, the same parts and components are designated by the same reference numerals. Their names and functions are the same. Therefore, the detailed description of these will not be repeated. In addition, each embodiment and each modification described below may be selectively combined as appropriate.

In the following embodiments, the image forming apparatus includes, for example, an MFP, a printer, a copier, a facsimile, or the like.

FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus 1 based on an embodiment.
FIG. 2 is a diagram illustrating a main part of a control system of the image forming apparatus 1 based on the embodiment.

The image forming apparatus 1 shown in FIGS. 1 and 2 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. That is, the image forming apparatus 1 transfers (primary transfer) the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photoconductor drum 413 to the intermediate transfer belt 421. ), And after superimposing the toner images of four colors on the intermediate transfer belt 421, the image is formed by transferring (secondary transfer) to the paper S.

Further, in the image forming apparatus 1, the photoconductor drums 413 corresponding to the four colors of YMCK are arranged in series in the traveling direction of the intermediate transfer belt 421, and the toner images of each color are sequentially transferred to the intermediate transfer belt 421 in one procedure. The tandem method is adopted.

As shown in FIG. 2, the image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper conveying unit 50, a fixing unit 60, a communication unit 70, and a control unit 100. Be prepared.

The control unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, and the like. The CPU 101 reads a program according to the processing content from the ROM 102, develops it in the RAM 103, and centrally controls the operation of each block of the image forming apparatus 1 in cooperation with the expanded program.

The ROM 102 and the RAM 103 are composed of, for example, a non-volatile semiconductor memory (so-called flash memory) or a hard disk drive.

The control unit 100 transmits and receives various data to and from an external device (for example, a personal computer) connected to a communication network such as a LAN (Local Area Network) or WAN (Wide Area Network) via the communication unit 70. conduct. The control unit 100 receives, for example, image data transmitted from an external device, and causes the paper S to form an image based on the image data (input image data). The communication unit 70 is composed of a communication control card such as a LAN card.

The image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder), a document image scanning device 12 (scanner), and the like.

The automatic document feeding device 11 conveys the document D placed on the document tray by the conveying mechanism and sends it out to the document image scanning device 12. The automatic document feeding device 11 can continuously read a large number of images (including both sides) of the documents D placed on the document tray at once.

The document image scanning device 12 optically scans the document conveyed on the contact glass from the automatic document feeding device 11 or the document placed on the contact glass, and the reflected light from the document is a CCD (Charge Coupled Device). ) An image is formed on the light receiving surface of the sensor 12a, and the original image is read. The image scanning unit 10 generates input image data based on the scanning result by the document image scanning device 12. The image processing unit 30 performs predetermined image processing on the input image data.

The operation display unit 20 is composed of, for example, a liquid crystal display (LCD) with a touch panel, and functions as a display unit 21 and an operation unit 22. The display unit 21 displays various operation screens, an image status display, an operation status of each function, and the like according to a display control signal input from the control unit 100. The operation unit 22 includes various operation keys such as a numeric keypad and a start key, receives various input operations by the user, and outputs an operation signal to the control unit 100.

The image processing unit 30 includes a circuit or the like that performs digital image processing according to initial settings or user settings on the input image data. For example, the image processing unit 30 performs gradation correction based on the gradation correction data (gradation correction table) under the control of the control unit 100. Further, the image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

The image forming unit 40 is an image forming unit 41Y, 41M, 41C, 41K, and an intermediate transfer unit 42 for forming an image with each colored toner of Y component, M component, C component, and K component based on the input image data. Etc. are provided.

The image forming units 41Y, 41M, 41C, and 41K for the Y component, the M component, the C component, and the K component have the same configuration. For convenience of illustration and description, common components are indicated by the same reference numerals, and when distinguishing them, they are indicated by adding Y, M, C, or K to the reference numerals. In FIG. 1, reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals are omitted for the other components of the image forming units 41M, 41C, and 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor drum 413, a charging device 414, a drum cleaning device 415, and the like.

The photoconductor drum 413 has, for example, an undercoat layer (UCL: Under Coat Layer) and a charge generation layer (CGL: Charge) on the peripheral surface of a conductive cylinder (aluminum element tube) made of aluminum having a drum diameter of 80 [mm]. It is a negatively charged organic photo-conductor (OPC) in which a generation layer (Generation Layer) and a charge transport layer (CTL) are sequentially laminated. The charge generation layer is made of an organic semiconductor in which a charge generation material (for example, a phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate), and a pair of positive charges and negative charges are generated by exposure by an exposure apparatus 411. The charge transport layer is composed of a hole transport material (electron donating nitrogen-containing compound) dispersed in a resin binder (for example, polycarbonate resin), and transports positive charges generated in the charge generation layer to the surface of the charge transport layer. do.

The photoconductor drum 413 rotates at a constant peripheral speed by controlling the drive current supplied to the drive motor (not shown) that rotates the photoconductor drum 413 by the control unit 100.

The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative electrode property. The exposure apparatus 411 is composed of, for example, a semiconductor laser, and irradiates the photoconductor drum 413 with a laser beam corresponding to an image of each color component. Positive charges are generated in the charge generation layer of the photoconductor drum 413 and transported to the surface of the charge transport layer, so that the surface charge (negative charge) of the photoconductor drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photoconductor drum 413 due to a potential difference from the surroundings.

The developing device 412 is, for example, a developing device of a two-component developing method, and visualizes an electrostatic latent image by adhering toner (oilless toner containing wax in toner particles) of each color component to the surface of the photoconductor drum 413. To form a toner image.

The drum cleaning device 415 has a drum cleaning blade or the like that is in sliding contact with the surface of the photoconductor drum 413, and removes the transfer residual toner remaining on the surface of the photoconductor drum 413 after the primary transfer.

The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer roller 424, a belt cleaning device 426, and the like.

The intermediate transfer belt 421 is composed of an endless belt, and is stretched in a loop on a plurality of support rollers 423. At least one of the plurality of support rollers 423 is composed of a driving roller, and the other is composed of a driven roller. For example, it is preferable that the roller 423A arranged on the downstream side in the belt traveling direction with respect to the primary transfer roller 422 for the K component is the drive roller. This makes it easier to keep the running speed of the belt in the primary transfer unit constant. As the drive roller 423A rotates, the intermediate transfer belt 421 travels at a constant speed in the direction of arrow A.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 421 so as to face the photoconductor drum 413 of each color component. By pressing the primary transfer roller 422 against the photoconductor drum 413 with the intermediate transfer belt 421 sandwiched between them, a primary transfer nip for transferring the toner image from the photoconductor drum 413 to the intermediate transfer belt 421 is formed.

The secondary transfer rollers 424A and 424B are arranged on the outer peripheral surface side of the intermediate transfer belt 421 so as to face the drive rollers 423A and 423B arranged on the downstream side in the belt traveling direction. The secondary transfer rollers 424A and 424B are pressed against the drive rollers 423A and 424B across the intermediate transfer belt 421 to form a secondary transfer nip for transferring the toner image from the intermediate transfer belt 421 to the paper S. NS.

When the intermediate transfer belt 421 passes through the primary transfer nip, the toner image on the photoconductor drum 413 is sequentially superimposed on the intermediate transfer belt 421 and the primary transfer is performed. Specifically, a primary transfer bias is applied to the primary transfer roller 422, and a charge opposite to that of the toner is applied to the back surface side (the side that abuts the primary transfer roller 422) of the intermediate transfer belt 421 to obtain a toner image. It is electrostatically transferred to the intermediate transfer belt 421.

After that, when the paper S passes through the secondary transfer nip, the toner image on the intermediate transfer belt 421 is secondarily transferred to the paper S. Specifically, a secondary transfer bias is applied to the secondary transfer rollers 424A and 424B, and a charge having a polarity opposite to that of the toner is applied to the back surface side of the paper S (the side that comes into contact with the secondary transfer roller 424). The toner image is electrostatically transferred to the paper S. The paper S on which the toner image is transferred is conveyed toward the fixing portion 60.

The belt cleaning unit 426 has a belt cleaning blade or the like that is in sliding contact with the surface of the intermediate transfer belt 421, and removes the transfer residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer.

The fixing portion 60 is arranged on the back surface (opposite surface of the fixing surface) side of the fixing member 60A having the fixing surface side member arranged on the fixing surface (the surface on which the toner image is formed) side of the paper S. A pressure member 60B having a back surface side support member to be formed, a heating source 60C, and the like are provided. By pressing the back surface side support member against the fixing surface side member, a fixing nip that narrowly holds and conveys the paper S is formed.

The fixing unit 60 fixes the toner image on the paper S by secondarily transferring the toner image and heating and pressurizing the conveyed paper S with the fixing nip. The fixing unit 60 is arranged as a unit in the fixing device F. Further, the fuser F may be provided with an air separation unit that separates the paper S from the fixing surface side member or the back surface side support member by blowing air. The details of the fixing portion 60 will be described later.

The paper transport unit 50 is controlled according to the instructions of the control unit 100.
The paper transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, a refeed unit 57, a transport path unit 53, and the like. Paper S (standard paper, special paper) identified based on the basis weight, size, etc. is stored in the three paper feed tray units 51a to 51c constituting the paper feed unit 51 for each preset type. .. The transport path portion 53 has a plurality of transport roller pairs such as a resist roller pair 53a.

The paper S housed in the paper feed tray units 51a to 51c is sent out one by one from the uppermost portion, and is conveyed to the image forming unit 40 by the transfer path unit 53. At this time, the resist roller portion in which the resist roller pair 53a is arranged corrects the inclination of the fed paper S and adjusts the transfer timing. Then, in the image forming unit 40, the toner image of the intermediate transfer belt 421 is collectively secondarily transferred to one surface of the paper S, and the fixing step is performed in the fixing unit 60. The image-formed paper S is discharged to the outside of the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

When the image is also formed on the back surface of the paper S, the paper S whose front surface has been image-fixed is conveyed to the re-feeding unit 57 below by the paper guide member 56.

The re-feeding unit 57 has a re-feeding reversing roller 71.
The re-feeding reversing roller 71 sandwiches the rear end of the paper S and then reverse-feeds the paper S to reverse the paper S and feeds the paper S to the re-feeding transfer path 72. It is sent out from the re-feeding transfer path 72 to the transfer path section 53 again. Then, it is transported to the image forming unit 40 by the transport path unit 53. Then, the toner image is secondarily transferred to the back surface of the paper S in the image forming unit 40, and the fixing step is performed in the fixing unit 60. The paper S having images formed on both sides is abolished outside the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

Further, in the case of the paper S having the embossed surface in the present embodiment, the paper S having been image-fixed on the embossed surface is conveyed to the re-feeding unit 57 below by the paper guide member 56. ..

The re-feeding reversing roller 71 sandwiches the rear end of the paper S and then reverse-feeds the paper S to reverse the paper S and feeds the paper S to the re-feeding transfer path 72. It is sent out from the re-feeding transfer path 72 to the transfer path section 53 again. Then, it is transported to the image forming unit 40 by the transport path unit 53. The paper S is conveyed to the fixing unit 60 as it is without transferring the toner image in the image forming unit 40. Then, a fixing step is performed on the fixing unit 60, and the paper discharging unit 52 provided with the paper discharging roller 52a abolishes the paper outside the machine. Therefore, in the case of the paper S having the embossed surface, the paper is passed through the fixing portion 60 twice.

A paper having an embossed surface will be described.
As a method of embossing, for example, there is a method of embossing by passing a base paper between the nips of a metal roll having an engraved pattern such as satin finish, cloth, or mesh and an elastic roll. In addition, a felt having a woven pattern peculiar to the felt used in the drying process of the paper machine is used, and various uneven patterns are given, such as a wet base paper that has progressed from the wire part to the dry part and the felt pattern is given. There is also a way to do it. A glue material is usually used to clarify the unevenness. Although it is not specified as the glue material, it is preferable to use a synthetic glue rather than a starch paste, particularly one that is water-soluble and becomes insoluble when individualized. Specifically, polyolefin resins such as polyethylene and polypropylene, polyester resins, polyether resins, polyamide synthetic resins, polystyrenes, poly (meth) acrylic acid esters, polyacrylonitol, polyvinyl acetate, vinyl alcohols and other vinyls. Examples thereof include resins, cellulose-based resins, simple substances of many other resins, solutions of copolymers, emulsions, aqueous resin solutions such as dispersions, and aqueous resin emulsions.

[Structure of fixing unit 60]
FIG. 3 is a diagram schematically explaining the configuration of the fixing portion 60 based on the embodiment.

With reference to FIG. 3, the fixing unit 60 and the control unit 100 function as a fixing device. The fixing unit 60 and the control unit 100 may be configured as a unit and attached to the image forming apparatus 1, or each may be separately incorporated into the image forming apparatus 1 to function as a fixing device. ..

The fixing member 60A has an endless fixing belt 61, a heating roller 62, and a pressure roller 63, which are members on the fixing surface side (belt heating method). The fixing belt 61 is stretched on the heating roller 62 and the pressure roller 63 with a predetermined belt tension.

The fixing belt 61 has, for example, an outer diameter of 50 [mm] and has a thickness of 150 [μm] on the outer peripheral surface of a base material layer (first base material layer) made of PI (polyimide) having a thickness of 80 [μm]. The elastic layer (first elastic layer) is coated with heat-resistant silicone rubber, and the outer peripheral surface of the elastic layer is 20 [μm] as a surface release layer (first surface release layer), which is a heat-resistant resin PFA. It is made by coating or coating a tube of (perfluoroalkoxy). The fixing belt 61 forms a fixing nip NP together with the pressure roller 65.

The fixing belt 61 comes into contact with the paper S on which the toner image is formed, and heats and fixes the toner image on the paper S at a fixing temperature (for example, 160 to 200 [° C.]). Here, the fixing temperature is a temperature at which the amount of heat required to melt the toner on the paper S can be supplied, and differs depending on the paper type of the paper S on which the image is formed.

The heating roller 62 heats the fixing belt 61. The heating roller 62 has a built-in heating source 60C (halogen heater (900W)) for heating the fixing belt 61. As an example, the heating roller 62 has an inner diameter of 25 [mm] and an outer diameter of 26 [mm]. For example, the outer peripheral surface of a cylindrical core metal formed of aluminum or the like is coated with a resin layer coated with PTFE. Has been done. The heating roller 62 has a black coating on the inner surface in order to enhance heat absorption from the halogen heater.

The temperature of the heating source 60C is controlled by the control unit 100. The heating roller 62 is heated by the heating source 60C, and as a result, the fixing belt 61 is heated.

The pressure roller 63 is formed by coating a solid core metal formed of a metal such as iron having an outer diameter of 20 [mm] with a heat-resistant silicone rubber having a thickness of 5 [mm] as an elastic layer. be.

The pressurizing member 60B has, for example, a pressurizing roller 65 which is a back surface side support member (roller pressurizing method).

In the pressure roller 65, for example, a solid core metal formed of a metal such as iron having an outer diameter of 20 [mm] is coated with a heat-resistant silicon rubber having a thickness of 5 [mm] as an elastic layer, and further. It is coated with a resin layer coated with PTFE, which is a low-friction, heat-resistant resin having a thickness of 50 [μm].

The pressure roller 63 is pressed against the pressure roller 65, which is driven and rotated by a main drive source (not shown) in the fixing portion 60, via the fixing belt 61.

The control unit 100 controls the main drive source (drive motor) to rotate the pressurizing roller 65 in the counterclockwise direction. Drive control of the drive motor (for example, rotation on / off, peripheral speed, etc.) is performed by the control unit 100.

As an example, the measured values of the fixing belt 61 and the pressure roller 65 with an Asker C hardness tester having a load of 9.6 N are measured as 70 ° and 50 °.

The pressure roller 65 and the fixing belt 61 are pressed against each other by the pressure roller 63 with a predetermined contact load (for example, 300 [N]). The peak pressure of contact between the pressurizing roller 65 and the fixing belt 61 is 80 kPa. In this way, a fixing nip NP that narrowly holds and conveys the paper S is formed between the fixing belt 61 and the pressure roller 65. The nip time of the paper S in the fixing nip NP is set to 70 msec.

The pressure roller 65 may include a heating source (not shown) such as a halogen heater. The pressure roller 65 is heated by the heat generated by this heating source. The control unit 100 can also control the electric power supplied to the heating source and control the pressurizing roller 65 to a predetermined temperature (for example, 80 to 160 [° C.]).

The silicon rubber layer of the fixing belt 61 is thinner than the rubber layer of the pressure roller 65 in order to shorten the start-up time from the standby state and enhance the heat responsiveness from the halogen heater. That is, the hardness of the fixing belt 61 is larger than the hardness of the pressure roller 65. In other words, the pressure roller 65 has a configuration in which the amount of deformation at the fixing nip is larger than that of the fixing belt 61.

The fixing belt 61 may have a simple structure in which only a release layer (a layer containing a fluororesin) is provided on the core metal without providing a rubber layer on the core metal.

Further, in this example, the case where the nip is formed by the fixing belt 61 and the pressure roller 65 as the nip forming member will be described, but the present invention is not particularly limited to this, and a pad configuration made of a support sheet metal and a resin may be used. .. It is also possible to adopt a belt direct heating method without a heating roller, an IH (Induction Heating) belt heating method, or a nip direct heating method using a planar heating element.

FIG. 4 is a flow chart illustrating a process of forming a toner image based on the embodiment.
With reference to FIG. 4, the image forming apparatus 1 determines whether or not the single-sided printing instruction has been received (step S0). Specifically, the control unit 100 determines whether or not the print job of the single-sided print setting has been accepted via the operation unit 22.

When the image forming apparatus 1 determines in step S0 that it has received the single-sided printing instruction (YES in step S0), it determines whether or not the printing paper is embossed paper (step S2). The control unit 100 determines whether or not the print paper is set as the embossed paper as the print job via the operation unit 22. It is assumed that "plain paper", "embossed paper", etc. can be selected in the print paper setting of the print job.

In step S2, when the image forming apparatus 1 determines that the printing paper is embossed paper (YES in step S2), the image forming apparatus 1 transfers the toner to the paper (step S4). The control unit 100 instructs the image forming unit 40 to transfer the toner image to the intermediate transfer belt 421. Then, the toner image is secondarily transferred to the paper S via the secondary transfer rollers 424A and 424B.

Next, the image forming apparatus 1 executes the fixing process (fixing member side) (step S6). Specifically, the second-transferred paper S is conveyed to the fixing nip NP between the fixing belt 61 and the pressure roller 65. At that time, the fixing member side and the embossed surface on which the toner image is transferred come into contact with each other.

Next, the image forming apparatus 1 executes the re-passing process (step S8). Specifically, the re-feeding reversing roller 71 sandwiches the rear end of the paper S and then reverse-feeds the paper S to reverse the paper S and feeds the paper S to the re-feeding transfer path 72. It is sent out from the re-feeding transfer path 72 to the transfer path section 53 again. Then, it is transported to the image forming unit 40 by the transport path unit 53. The paper S is conveyed to the fixing unit 60 as it is without transferring the toner image in the image forming unit 40.

Next, the image forming apparatus 1 executes the fixing process (pressurizing member side) (step S10). Specifically, the second-transferred paper S is conveyed to the fixing nip NP between the fixing belt 61 and the pressure roller 65. At that time, the pressure member side and the embossed surface on which the toner image is transferred come into contact with each other.

Next, the image forming apparatus 1 executes the paper ejection process (step S12). The paper S is abolished outside the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

Next, the image forming apparatus 1 ends the process (end).
On the other hand, in step S2, when the image forming apparatus 1 determines that the printing paper is embossed paper (NO in step S2), the image forming apparatus 1 transfers the toner to the paper (step S14).

The control unit 100 instructs the image forming unit 40 to transfer the toner image to the intermediate transfer belt 421. Then, the toner image is secondarily transferred to the paper S via the secondary transfer rollers 424A and 424B.

Next, the image forming apparatus 1 executes the fixing process (fixing member side) (step S16). Specifically, the second-transferred paper S is conveyed to the fixing nip NP between the fixing belt 61 and the pressure roller 65. At that time, the fixing member side and the paper S on which the toner image is transferred come into contact with each other.

Next, the image forming apparatus 1 executes the paper ejection process (step S12). The paper S is abolished outside the machine by the paper ejection unit 52 provided with the paper ejection roller 52a.

Next, the image forming apparatus 1 ends the process (end).
FIG. 5 is a diagram illustrating a fixing process of the paper S having an embossed surface based on the embodiment.

FIG. 5A schematically shows a contact state between the embossed paper having the embossed surface on which the toner is transferred and the fixing member 60A. As shown in the figure, heat is supplied to the toner transferred to the convex smooth surface of the embossed paper by direct heat conduction and heat transfer from the fixing member 60A. Direct heat conduction from the fixing member 60A has good conduction efficiency. On the other hand, heat is supplied to the toner in the concave groove portion of the embossed paper by radiant heat and heat transfer mediated by air from the fixing member 60A. Radiant heat mediated by air has poor conduction efficiency, so that sufficient thermal power cannot be applied to the toner.

In the present embodiment, as shown in FIG. 5B, the embossed paper S is passed through the fixing device for the second time. Specifically, the front and back sides are reversed and the embossed surface is set to be in contact with the pressure member 60B.

In this example, the pressure member 60B is set to have a larger elastic force than the fixing member 60A.

With this configuration, the surface of the pressure roller 65 follows the concave groove portion of the unevenness, and heat can be sufficiently transferred in close proximity.

In this configuration, by thinning the elastic layer on the side of the fixing member 60A, it is possible to improve the fixing property of the embossed paper without deteriorating the thermal responsiveness from the halogen heater.

In this example, the configuration in which the embossed surface and the fixing member 60A and the pressing member 60B are in contact with each other once has been described, but further, the fixing member 60A or the pressing member 60A or the pressing member is pressed a plurality of times by passing the paper through the fixing device. It is also possible to have a configuration in which the member 60B is in contact with the member 60B.

(Example 1)
FIG. 6 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the first embodiment.

FIG. 6 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the thickness [μm] of the elastic layer of the fixing member 60A. As an example, a case where the thickness of the elastic layer of the fixing member 60A is changed from 100 μm to 250 μm is shown.

In this example, a visual evaluation using a plastic eraser will be described.
A load of 1 kg is applied to reciprocate the toner image three times. After 3 reciprocations, it is visually evaluated whether or not image scraping occurs due to the reciprocation of the plastic eraser.

As shown in this example, it was confirmed that the image was scraped when the paper was passed once, but the image was not scraped when the paper was passed twice.

Further, by passing the paper twice, it is possible to secure sufficient fixing performance even if the thickness of the elastic layer (rubber) of the fixing member 60A is thin.

When the elastic layer (rubber) of the fixing member 60A becomes thick, the heat capacity of the fixing member 60A increases, the electric power consumed by the fixing device increases, and the warm-up time becomes long.

In this example, when the elastic layer thickness of the fixing member 60A is 190 μm or more, the warm-up time becomes long.

Therefore, it is desirable that the thickness of the elastic layer (rubber) of the fixing member 60A be as thin as possible from the viewpoint of energy saving.

In Example 1, it was confirmed that energy saving performance can be ensured and the fixability of the embossed paper can be ensured by setting the thickness of the elastic layer (rubber) of the fixing member 60A to 180 μm or less.

(Example 2)
FIG. 7 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the second embodiment.

FIG. 7 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the thickness (μm) of the elastic layer of the pressure member 60B. As an example, a case where the thickness of the elastic layer of the pressure member 60B is changed from 3 mm to 5 mm is shown.

If the thickness of the elastic layer of the pressurizing member 60B is thin, the concave groove portion of the embossed paper and the pressurizing member do not come into sufficient contact during the second paper passing.

When the thickness of the elastic layer of the pressure member 60B is 4.0 mm or less as in the second embodiment, the concave groove portion of the embossed paper and the pressure member 60B do not sufficiently contact each other, resulting in image scraping. The case is shown.

On the other hand, when the thickness of the elastic layer of the pressure member 60B is 4.2 mm or more, the concave groove portion of the embossed paper and the pressure member 60B are sufficiently in contact with each other to directly transfer heat and give a sufficient amount of heat to the toner. The case is shown.

Therefore, it was confirmed that the fixability of the embossed paper can be ensured by setting the elastic layer thickness of the pressure member 60B to 4.2 mm or more.

(Example 3)
FIG. 8 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the third embodiment.

FIG. 8 shows a case where the surface hardness of the pressure member 60B is changed to evaluate the fixability of the toner image of the embossed paper. As an example, a case where the surface hardness of the pressure member 60B is changed from 4 ° to 70 ° is shown. Here, the hardness when a load of 9.6 N is applied using an Asker C hardness tester is shown.

If the surface hardness of the pressurizing member 60B is high, the concave groove portion of the embossed paper and the pressurizing member do not come into sufficient contact with each other during the second paper passing.

As in the third embodiment, when the surface hardness of the pressure member 60B is 60 ° or more, the concave groove portion of the embossed paper and the pressure member 60B may not sufficiently contact each other, resulting in image scraping. It is shown.

When the surface hardness of the pressure member 60B is 54 ° or less, the concave groove portion of the embossed paper and the pressure member 60B are in sufficient contact with each other to directly transfer heat and give a sufficient amount of heat to the toner. ing.

Therefore, it was confirmed that the fixability of the embossed paper can be ensured by setting the hardness of the pressure member 60B to 54 ° or less.

(Example 4)
FIG. 9 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the fourth embodiment.

FIG. 9 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the contact force (N) between the fixing member 60A and the pressing member 60B. As an example, a case where the contact force between the fixing member 60A and the pressure member 60B is changed from 150N to 500N is shown.

If the contact force between the fixing member 60A and the pressure member 60B is reduced, the adhesion to the paper deteriorates, so that the fixing performance of the embossed paper cannot be ensured.

If the contact force between the fixing member 60A and the pressure member 60B is 150 N or less even when the paper is passed twice, the fixing performance cannot be ensured because the concave groove portion of the embossed paper and the pressure member 60B do not sufficiently contact each other.

When the contact force between the fixing member 60A and the pressurizing member 60B is 200 N or more as in the third embodiment, the concave groove portion of the embossed paper and the pressurizing member 60B are sufficiently in contact with each other, and the concave portion of the embossed paper is formed. The fixing performance of the groove part can be secured.

On the other hand, if the contact force between the fixing member 60A and the pressurizing member 60B is large, the load between the members becomes large, and the durability performance such as the destruction of the member (roller) may be deteriorated.

When the contact force between the fixing member 60A and the pressurizing member 60B is 500N as in the fourth embodiment, the durability performance may decrease.

Therefore, when the contact force between the fixing member 60A and the pressing member 60B is 475N or less, the recessed groove portion of the embossed paper and the pressing member are sufficiently in contact with each other to ensure the fixing property while ensuring the durability performance. I confirmed that I could do it.

(Example 5)
FIG. 10 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the fifth embodiment.

FIG. 10 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the peak pressure (N) due to the contact between the fixing member 60A and the pressing member 60B. As an example, a case where the peak pressure due to the contact between the fixing member 60A and the pressurizing member 60B is changed from 40 kPa to 150 kPa is shown.

If the peak pressure due to the contact between the fixing member 60A and the pressure member 60B is reduced, the adhesion to the paper deteriorates, so that the fixing performance of the embossed paper cannot be ensured.

Even if the paper is passed twice, if the peak pressure due to the contact between the fixing member 60A and the pressing member 60B is 40 kPa, the concave groove portion of the embossed paper and the pressing member 60B do not sufficiently contact each other, so that the fixing performance cannot be ensured.

When the peak pressure due to the contact between the fixing member 60A and the pressurizing member 60B is 50 kPa or more as in the fifth embodiment, the concave groove portion of the embossed paper and the pressurizing member 60B are sufficiently in contact with each other, and the embossed paper It is possible to secure the fixing performance of the concave groove portion of the paper.

On the other hand, if the peak pressure due to the contact between the fixing member 60A and the pressing member 60B is large, the surface layer wear of the fixing member 60A may occur at the edge of the paper or the like, and image noise may occur.

When the peak pressure due to the contact between the fixing member 60A and the pressing member 60B is 130 kPa or more as in the fifth embodiment, the surface layer wear of the fixing member 60A may occur.

Therefore, when the peak pressure due to the contact between the fixing member 60A and the pressure member 60B is 110 kPa or less, the concave groove portion of the embossed paper and the pressure member are sufficiently contacted and fixed while suppressing surface wear. It was confirmed that sex could be secured.

(Example 6)
FIG. 11 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the sixth embodiment.

FIG. 11 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B. As an example, a case where the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is changed from 20 msec to 130 msec is shown.

If the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is short, the adhesion to the paper is weakened, so that the fixing performance of the embossed paper cannot be ensured.

When the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is 20 msec even when the paper is passed twice, the pressing member 60B sufficiently heats the concave groove portion of the embossed paper. Since it cannot be done, the fixing performance cannot be ensured.

As in the sixth embodiment, when the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is 40 msec or more, the pressing member is applied to the concave groove portion of the embossed paper. It was confirmed that 60B can perform sufficient heating and can secure the fixing performance.

On the other hand, if the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is long, the amount of heat taken by the pressing member 60B increases, so that the consumption required for the fixing member 60A is large. The power consumption increases and the energy saving performance deteriorates.

When the nip time passing through the fixing nip NP formed between the fixing member 60A and the pressing member 60B is 90 msec or less as in the sixth embodiment, the fixing performance of the embossed paper is ensured while suppressing the power consumption. I confirmed that I could do it.

Therefore, it is desirable that the control unit 100 controls the paper transport unit 50 to set the time for the embossed paper to pass through the fixing nip NP to 40 msec or more and 90 msec or less.

(Example 7)
FIG. 12 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the seventh embodiment.

FIG. 12 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the speed of the second paper passing. As an example, the case where the speed is changed from 100 msec to 450 msec is shown.

When the speed of the second paper passing (mm / sec) is slower than the speed of the first paper passing, sufficient adhesion to the paper can be ensured, so that the fixing performance of the embossed paper is high. On the other hand, if the speed of the second paper passing is slow, it takes time to eject the paper and the processing time becomes slow.

When the speed of the second paper passing is 450 mm / sec, the adhesion with the paper is weakened, so that the fixing performance cannot be ensured.

It was confirmed that when the speed of the second paper passing was 300 mm / sec or less as in Example 7, the processing time could be increased and the fixing performance of the embossed paper could be ensured.

Therefore, it is desirable that the control unit 100 controls the paper transport unit 50 to make the speed of passing the embossed paper to the fixing nip NP slower than the speed of passing the embossed paper for the first time.

(Example 8)
FIG. 13 is a diagram for explaining the evaluation result of the fixing process of the embossed paper based on the eighth embodiment.

FIG. 13 shows a case where the fixability of the toner image of the embossed paper is evaluated by changing the temperature (° C.) of the pressurizing member 60B at the time of the second paper passing. As an example, a case where the temperature of the pressurizing member 60B is changed from 50 ° C. to 160 ° C. is shown.

When the temperature of the pressurizing member 60B at the time of the second paper passing is 50 ° C. or lower, the pressurizing member cannot sufficiently heat the concave groove portion of the embossed paper, so that the fixing performance cannot be ensured.

When the temperature of the pressurizing member 60B at the time of the second paper passing is 80 ° C. or higher, the pressurizing member 60B can sufficiently heat the concave groove portion of the embossed paper, so that the embossed paper can be sufficiently heated. It was confirmed that the fixing performance could be stored.

Therefore, when the temperature of the pressurizing member 60B reaches a predetermined temperature (80 ° C. as an example), the control unit 100 controls the paper transport unit 50 to pass the embossed paper to the fixing nip NP for the second time. It is desirable to do.

At this point, it is possible to raise the temperature of the pressurizing member 60B via the fixing member 60A by idling the fixing member 60A (fixing belt).

The control unit 100 can control the temperature of the pressurizing member 60B by instructing the fixing unit 60 to adjust the time for idling the fixing member 60A.

Therefore, the control unit 100 controls the paper transport unit 50 with respect to the fixing nip NP after executing the idle rotation process for a predetermined period so that the temperature of the pressurizing member 60B becomes a predetermined temperature (80 ° C. as an example). It is desirable to pass the embossed paper a second time.

(Other forms)
In the above embodiment, the case where the user selects "embossed paper" in the setting of the printing paper via the operation unit 22 to execute the process of passing the paper twice in the fixing device has been described, but the paper S has been described. The above process may be executed by automatically determining whether or not the paper is embossed. Specifically, it is also possible to provide a media sensor capable of detecting the surface roughness, basis weight, thickness, etc. of the paper S, and automatically determine whether or not the paper is embossed paper based on the sensing process of the media sensor. be.

In this example, the case where it is mainly used for an image forming apparatus has been described, but the method is not particularly limited to the image forming apparatus, and the method can be used for other purposes in general.

It should be considered that the embodiments and examples disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

1 image forming device, 10 image reading unit, 11 automatic document feeding device, 12 document image scanning device, 12a CCD sensor, 20 operation display unit, 21 display unit, 22 operation unit, 30 image processing unit, 40 image forming unit, 42 Intermediate transfer unit, 50 Paper transport section, 51 Paper feed section, 52 Paper discharge section, 52a Paper discharge roller, 53 Transport path section, 53a Resist roller pair, 56 Paper guide member, 57 Refeed section, 60 Fixing section, 60A fixing member, 60B pressurizing member, 60C heating source, 61 fixing belt, 62 heating roller, 63,65 pressurizing roller, 70 communication unit, 71 re-feeding reversing roller, 72 re-feeding transfer path, 100 control unit, 102 ROM, 103 RAM, 411 exposure device, 412 developing device, 413 photoconductor drum, 414 charging device, 415 drum cleaning device, 421 intermediate transfer belt, 422 primary transfer roller, 423 support roller.

Claims (13)

A fixing member for fixing the toner carried on the paper to be passed, and a fixing member.
A pressure member for forming a nip with the fixing member is provided.
The fixing member does not have an elastic layer having a thickness of 180 μm or less or the elastic layer.
The surface hardness of the fixing member is larger than the surface hardness of the pressure member.
After it passed the the paper carrying the toner to the nip, and re sheet path for re-passing the paper to the nip by reversing the front and back of the paper,
If the print job has a print paper setting with an embossed surface, the paper is conveyed to the nip via the re-passage path, and the print job does not have a print paper setting with an embossed surface. In the case of an image forming apparatus, the nip is further provided with a control unit that does not convey the paper through the reprint path. The image forming apparatus according to claim 1, wherein the pressure member has an elastic layer having a thickness of 4.2 mm or more. The image forming apparatus according to claim 1 or 2, wherein the surface hardness of the pressure member is set to 54 ° or less as measured by an Asker C hardness tester when a load of 9.6 N is applied. The image forming apparatus according to any one of claims 1 to 3, wherein the contact force that abuts the fixing member and the pressurizing member is set to 200 N or more. The image forming apparatus according to claim 4, wherein the contact force that abuts the fixing member and the pressurizing member is set to 475 N or less. The image forming apparatus according to any one of claims 1 to 5, wherein the peak pressure due to the contact between the fixing member and the pressurizing member is set to 50 kPa or more. The image forming apparatus according to claim 6, wherein the peak pressure due to the contact between the fixing member and the pressurizing member is set to 110 kPa or less. The image forming apparatus according to any one of claims 1 to 7, wherein the control unit sets the time for passing through the nip formed by the fixing member and the pressurizing member to 40 msec or more. The image forming apparatus according to claim 8, wherein the control unit sets the time for passing through the nip formed by the fixing member and the pressurizing member to 90 msec or less. The one according to any one of claims 1 to 9, wherein the control unit conveys the paper to the nip at a speed slower than the speed at which the paper is first passed through the nip. Image forming device. The image forming apparatus according to any one of claims 1 to 10, wherein the control unit conveys the paper to the nip when the temperature of the pressurizing member becomes equal to or higher than a predetermined temperature. The image forming apparatus according to claim 11, wherein the control unit conveys the paper to the nip after the fixing member has idlely rotated for a predetermined period of time. A method for controlling an image forming apparatus, which includes a fixing member for fixing a toner carried on a paper to be passed and a pressure member for forming a nip between the fixing members.
The fixing member does not have an elastic layer having a thickness of 180 μm or less or the elastic layer.
The surface hardness of the fixing member is larger than the surface hardness of the pressure member.
A step of passing the paper carrying the toner through the nip, and
And a step of re-passing the paper to the paper by inverting the nip the front and back of the paper,
The step of re-passing the paper is
When the print job has a setting of printing paper having an embossed surface, the front and back sides of the paper are reversed and the paper is re-passed through the nip.
A control method for an image forming apparatus , in which, when the print job does not have a setting for printing paper having an embossed surface, the front and back sides of the paper are reversed so that the paper is not re-passed through the nip.

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