JP4845374B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus and an image forming method, such as a printer, a copier, a facsimile machine, and a multi-function machine using an electrophotographic system, an electrostatic recording system, and the like.

  In recent years, color printers and color copiers that use digital electrophotography have become widespread due to an increasing number of uses for forming color images. In recent years, the image quality of the color image has been improved, and in recent years, it has been increasingly used for image output of a digital still camera in which the market is conspicuous. Therefore, as an image forming apparatus such as a printer or a copying machine using an electrophotographic method, an image having a normal image quality can be output, and a high image quality comparable to that of a silver salt photograph can be obtained. A device capable of outputting an image having a glossy image quality is required.

  Therefore, conventionally, for example, an image forming method capable of obtaining a color image having excellent gloss has been proposed (Patent Document 1). The image forming method is a method in which a color toner attached on a transparent resin layer made of a thermoplastic resin on the surface of a transfer body (recording sheet) is heated and transparent by a belt-like conveyance body that moves under a member containing a heat source. In this method, the resin layer is melted and then cooled and fixed, and the transfer body is further separated from the belt-shaped transport body to form a color image.

  There has also been proposed an image forming apparatus that can select between formation of a glossy image and formation of a non-glossy image (Patent Document 2). The image forming apparatus includes a first fixing device and a second fixing device arranged in series along a recording sheet conveyance path, and one of the fixing devices is a roller fixing device and the other is a belt fixing device. In addition, in the non-gloss mode, only the roller fixing device is operated, and in the gloss mode, at least the belt fixing device is operated.

  More recently, double-sided image formation has been performed on an image forming apparatus as described above, which forms a high-gloss image on one side and an image having a normal image quality (non-gloss, low gloss, etc.) on the other side. It has been required to have a function that can be used. For example, a digital still camera photographic image or the like is formed on one side of a postcard, and an address or other image is formed on the other side. As an image forming apparatus in which such double-sided image formation can be favorably selected separately from single-sided and double-sided image formation with normal image quality, a proposal of an image forming apparatus described in Patent Document 3 is known.

  The image forming apparatus includes an image forming apparatus that forms a toner image on a recording sheet, and a reverse conveyance path that branches between two fixing devices arranged in series in the subsequent conveyance path. The recording sheet on which the first image is output on the first surface by the image device and the first fixing device is conveyed on the reverse conveyance path, and the second surface is conveyed on the second surface by the image forming device and the first fixing device. After the second image is formed, the image is conveyed to the second fixing device and subjected to a second fixing process.

  In the image forming apparatus, a second image forming apparatus that forms an image that does not require fixing processing is disposed on one side of the recording sheet following the second fixing apparatus, and the recording sheet is formed on the first image forming apparatus. The image is conveyed to the image fixing device and the first fixing device, and the first image is output on the first surface of the recording sheet. Then, the image is conveyed to the second fixing device and subjected to the second fixing process. A device that is conveyed to the image forming apparatus and operates to form a second image on the second surface of the recording sheet is also presented.

  Further, there has been proposed an example in which the second image forming device is installed at a position facing the fixing belt in the second fixing device and a double-sided image forming operation is executed.

Conventionally, an image forming apparatus capable of high-speed double-sided copying and printing has been proposed (Patent Document 4). In this image forming apparatus, the first image forming unit and the second image forming unit are arranged so as to have a vertical positional relationship, and the first image is formed on one surface of the first image forming unit. The recording sheet is turned upside down along the U-turn portion and led to the second image forming portion, and the second image is formed on the other surface of the recording sheet. Further, one or both of the first and second image forming units is an image forming unit using electrophotography or an image forming unit using inkjet printing.
JP-A-5-216322 JP-A-5-158364 JP 2004-151259 A JP-A-11-174744

  In the color image forming method described in Patent Document 1, the configuration of the double-sided image formation is not clarified. If double-sided image formation is performed by the color image forming method, the surface of the transparent resin layer in the transfer body passes in a state of being in contact with a pressure roll arranged in pressure contact with the belt-like conveyance body. In addition, since the surface of the pressure roll is low in releasability, the transfer body is wound around the pressure roll due to the adhesiveness of the thermoplastic resin of the transparent resin layer heated and melted by the belt-shaped conveyance body. Trouble may occur.

  In addition, in the image forming apparatus described in Patent Document 2, the configuration of the single-sided image forming operation for forming a high-gloss image or a non-glossy image on one side of the recording sheet is obvious, but the configuration of double-sided image formation is also used. Is not disclosed. If double-sided image formation is to be performed with the image forming apparatus, two fixing devices in which recording sheets are always arranged in series or one of them is used not only during double-sided image formation but also during single-sided image formation with normal image quality. The recording sheet conveyance path configuration tends to be complicated because it must pass through a path including a conveyance path that bypasses the fixing device.

  Recently, as proposed in Patent Document 3, there has been proposed an image forming apparatus capable of forming a double-sided image with a high gloss image quality comparable to a silver salt photograph. However, in these proposals, it is necessary to add mechanism units to the conventional image forming apparatus one after another, which increases the cost, increases the installation size, and lengthens the recording sheet conveyance path. The initial productivity (F-COT: first copy time) may be inferior. Copy shops that actually require printing on the back side of high-gloss silver-salt photos have limited installation locations and equipment installation costs, and can be installed compactly, resulting in high-gloss images of silver-salt photographic tone and simultaneous back-side printing. There is an increasing demand for an image forming apparatus having a popular price.

  However, in the case of the image forming apparatus described in Patent Document 4, the recording sheet must pass through the same conveyance path as that for double-sided image formation even when forming a single-sided image with normal image quality, and the image output time becomes long. , Tend to be wasteful. That is, also in this proposal, the image forming apparatus is increased in size and cost. Further, when the U-turn portion is constituted by the suction roller as in the embodiment, the recording sheet is curled (described in paragraph 0021), so that the second image is formed on the curved recording sheet. There is a risk that a correct image cannot be formed.

  The present invention has been made to solve the above-described problems, and the main object of the present invention is to form a high-gloss image on at least one side of the recording sheet and non-glossy or low-side on the other side. To provide a compact image forming apparatus capable of satisfactorily performing double-sided image formation for forming a glossy image at low cost.

The present invention includes an image forming means for forming an image on a recording material, a fixing rotator for thermally fixing an image on a recording material at a nip portion, and first heating means for heating the fixing rotator, onto the recording material a belt member for a nip portion for heating the image conveying the recording material and forming said fixing rotary body, a second heating means for heating the belt member, the nip portion in the rotational direction of said belt member cooling and separation roller for separating the recording material on the belt member from the belt member on the downstream side, the area of the belt member of the separation roller upstream from the downstream side of the nip portion in the rotational direction of said belt member a cooling means for the, in an image forming apparatus capable of forming images on both sides of the recording material, the unfixed toner image formed on the recording material by said image forming means in contact with the fixing rotator Low gloss to said fixing rotary body and the and the belt member is arranged, the other surface to form a highly glossy image on one surface of the recording material to the recording material transported to the fixing on the recording material by When forming an image, the image formed on one side of the recording material is fixed by the fixing rotator, and then the front and back sides of the recording material are reversed and the image formed on the other side forms a low-gloss image. Therefore, the image is fixed on the recording material by the fixing rotating body heated by the first heating means at the nip portion, and the image formed on one surface is heated at the nip portion to form a high gloss image. When the low-gloss image is formed on both sides of the recording material by the belt member heated by the means, the image formed on one side of the recording material is fixed by the fixing rotator. After that, it is formed on the other side by reversing the front and back of the recording material. The image is fixed on the recording material by the fixing rotating body heated by the first heating unit at the nip portion, and the image formed on one surface is in a state where the energization to the second heating unit is stopped. It contacts with the said belt member .

  According to the present invention, it is possible to satisfactorily form a high gloss image on one side of the recording material and a low gloss image on the other side.

  Furthermore, according to the present invention, the apparatus configuration for forming a high gloss image on one side of the recording material and a low gloss image on the other side can be reduced in size.

  FIG. 1 shows an example of an image forming apparatus provided with a fixing device that can be applied.

  The apparatus main body 200 shown in this figure is a multicolor image forming apparatus (color copying machine) having a fixing device 1. Even if the image forming apparatus is a monochrome image, the gist of the image forming apparatus does not change.

  The apparatus main body 200 includes a document placing table 206, a light source 207, a lens system 208, a paper feeding unit 209, an image forming unit 202, and the like. The paper feeding unit 209 includes cassettes 210 and 211 and a manual feed cassette 212 that accommodate a transfer material and is detachable from the apparatus main body 200, and the transfer material is supplied from the cassettes 210 and 211 and the manual feed cassette 212. In the image forming unit 202, a black developing device 203 configured independently, a cylindrical photosensitive drum 213, a primary charger 214, and a rotary developing device 201 incorporating a plurality of developing devices 215 integrated with a toner cartridge, Post charger 216 for adjusting the image quality after development. Endless annular transfer belt 217 for transferring a multicolor image onto a transfer material after four-color toner images are transferred onto the transfer material, and cleaning residual toner on the photosensitive drum. A drum cleaner 218 that performs transfer, a secondary transfer roller 219 that transfers a toner image from a transfer belt to a transfer material, a belt cleaner 220 that cleans residual toner on the transfer belt, and the like are provided. On the upstream side of the image forming portion, the posture position accuracy of the transfer material is improved, and a registration roller 221 that feeds the transfer material in a timely manner in accordance with the toner image on the transfer belt, and the transfer material S on which the toner image is transferred on the downstream side. The transfer conveying device 222 that conveys, and the most characteristic fixing device 1 that fixes an unfixed image on the transfer material S, the discharge roller 205 that discharges the transfer material S on which the image is fixed, to the outside of the image forming device, etc. Is arranged.

  The operation of this image forming apparatus will be described.

  When a paper feed signal is output from a control device (not shown) provided on the apparatus main body 200, the transfer material S is supplied from the cassettes 210 and 211 or the manual feed cassette 212. On the other hand, the light reflected from the light source 207-1 and applied to the document D placed on the document table 206 is once read by the CCD unit 207-2 and then converted into an electrical signal from the laser scanner unit 208. The photosensitive drum 213 is irradiated with the laser beam. The photosensitive drum 213 is charged in advance by a primary charger 214, and an electrostatic latent image is formed by light irradiation, and then a plurality of developing units disposed in the black developing unit 203 and the rotary developing unit 201. By 215, the toner image of the selected color is formed.

  The potential of the toner image formed on the photosensitive drum is adjusted by the post charger 216, and is eventually transferred onto the transfer belt 217 at the transfer position. When the transferred toner image is in the color mode, the transfer belt is further rotated once so that the next toner image is formed and transferred. During this time, the rotary developing device 201 rotates the next designated color developing device in the direction of the arrow a so as to face the photosensitive drum 213 and prepares to develop the next electrostatic latent image. Thus, in the full-color mode, electrostatic latent image formation, development, and transfer are repeated until a predetermined number of toner images have been transferred.

  By the way, the transfer material S fed from the paper feeding unit 209 is corrected in skew by the registration roller 221 and further sent to the image forming unit 202 at a proper timing. The toner image is transferred by the secondary transfer roller 219, and the separated transfer material S is transported to the fixing device 1 by the transport device 222, and the unfixed transfer image is transferred to the transfer material S by the heat and pressure of the fixing device 1. Is permanently fixed. The transfer material S on which the image is fixed is discharged from the apparatus main body 200 by a discharge roller 205.

  In this way, the transfer material S fed from the paper feeding unit 209 forms an image and is discharged.

  The image forming apparatus 200 has a double-sided image forming function. This double-sided image forming operation will be described mainly based on the conveyance state of the transfer material S. The transfer material S after the fixing of the first surface by the fixing device 1 is branched downward by a reverse flapper mechanism indicated by 111 in the figure, and is conveyed to a reverse conveyance path 101 disposed downstream of the reverse branch point. . Next, the transfer material S that is switched back by the reverse conveyance path 101 is branched by the double-sided flapper mechanism 102 in a state where the front and back sides are reversed, and is drawn into the double-sided conveyance path 102 and retransmitted to the image forming unit. Has been. Incidentally, if the paper is discharged by the discharge roller 205 while being reversed from the reverse conveyance path 101, it functions as a reverse paper discharge mode.

  Thus, the transfer material S re-conveyed in the reverse conveyance path 101 and the double-sided conveyance path 102 is eventually retransmitted to the registration roller 221. Thus, a toner image is formed on the second surface of the transfer material S. Other image forming processes and the transfer process of the transfer material S are not different from the above-described single-sided image forming mode, and are not described here.

  FIG. 2 is a diagram showing a main cross section of the fixing device 1 having the most characteristic features. The fixing device 1 basically has a heating roller 6 and a belt body 5 arranged in pressure contact with each other. The heating roller 6 is formed by coating an elastic layer (for example, a silicone rubber layer having a JIS-A rubber hardness of about 40 °) and a release layer (for example, a fluororesin tube such as PFA) on a metal cylindrical roll having high thermal conductivity. And the halogen heater 6-1 which heats a heating roll is arrange | positioned inside the roll, and it is comprised so that it can act also as a pressure roller simultaneously with the function as a heating roller. In this embodiment, the temperature adjustment temperature of the superheat roller 6 is set to 200 ° C., and good fixability is ensured even when a four-color toner image is fixed. Note that the temperature control temperature of the fixing device is not limited to this, and it is needless to say that the number of developing devices (type of toner) is not limited to this.

  The belt body 5 is formed by forming a release layer (for example, a PFA tube having a thickness of 30 μm) on a belt base material made of a polyimide film having a thickness of about 75 μm, and is driven to rotate in the direction of arrow b in the figure. The In a normal fixing operation, it acts as a pressure belt and is pressed against the heating roller 6, and a good fixing property is secured by pressing the transfer material S against the heating roller 6. .

  First, the operation of the fixing device 1 according to the embodiment for fixing normal low-gloss and non-gloss images will be described. When the transfer material S on which the unfixed toner image created by the image forming unit is placed is sent to the fixing device 1, the transfer material S passes through the nip between the heating roller 6 and the belt body 5. The toner is heated and pressurized, and the unfixed toner is dissolved and fixed as a permanent toner image by the amount of heat and pressure.

  Incidentally, the fixing device 1 also has an effective fixing means for obtaining a high-quality image having an image quality such as high gloss at the same time. This is the most characteristic part. The most characteristic configuration of the belt 5 will be described in more detail with reference to FIG. As shown in the figure, the pressure belt 5 includes a heating roller 2 that is different from the pressure roller 6 described above, a peeling roller 3, a steering roller 4, and a belt body wound around the rollers 2-4. 5 and the above-described heating roller 6 that acts as a pressure roller for pressing the belt body 5 against the heating roller 2 to form a nip, and a cooling device 7 for cooling a portion of the belt body 5 on the downstream side of the nip. ing.

  The heating roller 2 is formed by coating a release layer (for example, a fluororesin tube of PFA or the like) on a metal cylindrical roll having high thermal conductivity, and disposing a halogen heater 2-1 inside the roll. The peeling roller 3 is for peeling the transfer material S from the belt body 5 by its own rigidity. The outer dimension of the roller 3 is determined by the adhesion force between the belt body 5 and the transfer material S and the winding angle of the belt body 5 around the peeling roller 3. The steering roller 4 is for adjusting the traveling direction of the belt body 5 in order to prevent the end of the belt from being damaged due to the offset running that occurs when the belt body 5 rotates. Specifically, one shaft of the roller 4 is fixed in position, and the other shaft is displaced so as to be inclined with respect to the axis of the heating roller 2 by a displacement mechanism (not shown).

  The belt body 5 is formed by coating a thermosetting polyimide endless film (75 μm or more) with a surface layer (30 μm or more) such as silicone rubber having a smooth surface. The cooling device 7 is for cooling the transfer material S that is actually in close contact with the belt body 5. The cooling device 7 is disposed in the inner peripheral surface region of the belt body 5 between the heating roller 2 and the peeling roller 3, and contacts the inner peripheral surface to absorb the heat of the belt body 5, for example, It consists of a heat sink and the like. The cooling target temperature of the cooling device 7 varies depending on the toner used, the type of the image receiving layer of the recording sheet, and the like, but is generally a temperature at which the temperature of the transfer material S on the belt 5 is 60 to 80 ° C. is there.

  Next, a high gloss image fixing operation by the fixing device 1 will be described. First, in the embodiment, the following method is adopted as one method for obtaining a high gloss image. When the operator who requests the output requests the output of the high gloss image, the transfer material S for outputting the high gloss image (preferably) is used. As this high-gloss image output transfer material, a gloss output transfer material S2 in which a transparent image receiving layer 52 made of a thermoplastic resin is provided on one surface of a sheet-like substrate 51 as shown in FIG. 3 is used. Such a gloss output transfer material S2 has a uniform gloss on the entire surface on which the image receiving layer 52 is formed (FIGS. 3A and 3B). In the special output mode, even if coated paper or the like is used as the transfer material S, an image with a certain degree of gloss can be output.

  On the other hand, as the transfer material S for the general output mode, if non-glossy image output is to be performed, a sheet of plain paper or the like having a specified size such as A4 plate or B5 plate is used which has almost no gloss. If low-gloss image output is to be performed, a coated sheet or other sheet itself having a smooth surface and slightly glossy is used.

  When the transfer material S after fixing the low-gloss and non-gloss images is sent again to the fixing device 1, the transfer material S is formed by the belt body 5 and the heating roller 6 acting as a pressure roller this time. The sheet is heated and pressurized by passing through the nip therebetween, and is transported while being in close contact with the belt body 5 even after passing through the nip. Subsequently, the transfer material S in close contact with the belt body 5 is cooled to a predetermined temperature (60 to 80 ° C.) by the cooling device 7, and then peeled off from the belt body 5 at a portion where the peeling roller 3 is located. Accordingly, the toner image fixed twice by the fixing device 1 is fixed again on the transfer material S in a state where the smooth surface of the belt body 5 is transferred and glossiness is imparted. The transfer material S after fixing is discharged onto a discharge tray by a discharge roller pair 205.

  FIG. 4 shows a block diagram of a control system for controlling the fixing device 1 in FIG. FIG. 5 is a flowchart showing a double-sided image creation pattern of the image forming apparatus 200 in the embodiment. In accordance with these drawings, the double-sided image creation mode, which is a characteristic point, will be described.

  The controller controls the operation of the entire system of the image forming apparatus, and sends necessary control signals to the image forming unit 202, the paper feeding unit 209, the fixing device 1, the image reading unit 207, the optical system 208, and the like. It is supposed to be sent out. This controller comprises a microcomputer composed of a CPU, ROM, RAM, etc., and the contents of selection instruction information input from a control program, operation unit, and other OA devices stored in a memory such as ROM. The control operation is executed according to the above. A control program related to each operation described later is also stored in a memory such as a ROM.

  The operation unit is provided with keys for inputting instructions for setting, selecting, determining, and executing various conditions for using the image forming apparatus. The display unit is configured to display input information and the like. The display unit may be a general liquid crystal display screen or a lamp. Usually, a touch panel type liquid crystal display screen capable of instructing and inputting information in addition to displaying information is used. The instruction information input through the operation unit is transmitted to the controller. In addition, a predetermined display is performed on the display unit according to the control operation of the controller, the output status from other OA devices, and the like.

  In the image forming apparatus according to the embodiment, as shown in FIG. 4, image output (copying) with general image quality (low-gloss, non-gloss image quality) is performed by giving predetermined instructions from the operation unit and other OA devices. , Printing) and a special output mode (gloss imparting mode) in which image output with high glossiness is performed on one side of the transfer material can be selected. Further, in either the general output mode or the special output mode, either single-sided output or double-sided output can be selected. The selection instruction at this time is performed directly by displaying a predetermined input screen or the like from an operation unit including a touch panel type liquid crystal display screen, or in combination with a selection input operation from another OA device.

  In the image forming apparatus, the transfer material S corresponding to each of the output modes described above is set to be used from the viewpoint of surely outputting an image having a desired image quality.

  Hereinafter, main operations (operations after the image forming process) of the image forming apparatus when the above-described output modes are selected will be described.

  When there is an output request from the operation unit or another OA device, the controller first determines the output mode. For example, when the transfer material S1 is fed from the paper feed cassette 210 containing the transfer material S1 such as plain paper or coated paper through the paper feed conveyance path, the controller determines that the image to be formed is low gloss or non-gloss. Judgment is made (step 1). Then, the toner image created by the image forming unit 202 is transferred and conveyed to form an unfixed toner image (non-glossy or low-gloss image) on one side (first side) of the transfer material S1. (Step 2). During this time, the controller instructs rotation of the fixing motor and voltage application of the halogen heater 6-1 of the heating roller 6 (steps 3 and 4). In this way, the unfixed toner image of the transfer material S1 conveyed by the transfer conveyance device 222 and sent to the fixing device 1 is fixed as a permanent toner image (step 5). Subsequently, the controller determines whether or not the transfer material S1 after the first surface fixing is in the duplex mode (step 6). When the image of the transfer material S1 is formed in the double-sided mode, it is reversely conveyed to the reverse conveyance path 101 by the reverse flapper mechanism 111 (step 7), and then conveyed to the double-sided path 102 by the double-side flapper mechanism 112 (step8). ).

  The transfer material S1 re-conveyed in the reverse conveyance path 101 and the double-sided conveyance path 102 is eventually retransmitted to the registration roller 221 and a toner image is formed on the second surface of the transfer material S (step 9). The transfer material S1 onto which the unfixed toner image (non-glossy or low-gloss image) is transferred on the second surface is sent again to the fixing device 1 by the transfer conveyance device 222. Thus, the unfixed toner image on the second surface of the transfer material S1 is melted by the heat amount and pressure of the fixing device 1 and fixed as a permanent toner image (step 10). Next, the sheet is discharged by the discharge roller 205 (in a state where the image surface is the upper surface) (Step 11). Finally, the controller gives an instruction to stop various motors / heaters (step 12), and the control sequence ends. Thereby, a non-glossy or low-gloss image is formed on both surfaces of the transfer material S1. In the case of this double-sided output, since the fixing process at the time of image formation on each side only heats and fixes only on one surface (heating roller 6) side of the fixing device 1, as in the case of passing through a plurality of fixing devices. Therefore, it is possible to form a relatively fast double-sided image without any time loss and to realize a low-power and compact image forming apparatus.

  On the other hand, returning to (Step 6), if the single-sided output mode is instructed in the normal output mode consisting of low gloss and non-gloss images, the controller discharges the transfer material S1 as it is by the discharge roller 205 (Step 13). Finally, the controller gives an instruction to stop various motors / heaters (step 12), and the control sequence ends. In the description using the flowchart, the recording surface of the transfer material S to be discharged is described only in the upper surface (face up) mode. However, when the recording surface is discharged from the lower surface, it is temporarily reversed as described above. What is necessary is just to discharge with the discharge roller 205, after conveying to the conveyance path 101. However, from the gist, the direction of the recording surface of the transferred transfer material S is not particularly limited, and it does not matter either.

  Next, returning to (step 1), the case where the controller selects the special output mode will be described. For example, when the transfer material S2 is fed through the paper feed conveyance path from the paper feed cassette 211 in which the gloss output transfer material S2 is accommodated, the controller determines that the special output mode (gloss imparting mode) has been selected. Here, in order to transfer the toner image to the image receiving layer surface side, it is necessary to feed the transfer material S2 so that the image receiving layer 52 is positioned on the transfer surface side. It is necessary to accommodate in a state where the surface with 52 is the lower surface.

  Even when the transfer material S2 determined to have high gloss has been conveyed to the transfer conveyance device 222, the toner image created by the image forming unit 202 is transferred and conveyed, so that one side (first surface) of the transfer material S2 is transferred. An unfixed toner image (image for high gloss output) is formed on the first surface (step 15). During this time, the controller instructs rotation of the fixing motor and voltage application of the halogen heater 6-2 of the heating roller 6 (steps 16 and 17). Thus, the unfixed toner image of the transfer material S2 conveyed by the transfer conveying device 222 and sent to the fixing device 1 is fixed as a permanent toner image (step 18). Subsequently, the controller determines whether or not the transfer material S1 after the first surface fixing is in the double-sided mode (step 19). When the transfer material S2 is instructed to form an image in the double-side mode, it is reversely conveyed to the reverse conveyance path 101 by the reverse flapper mechanism 111 (step 20), and then conveyed to the double-sided path 102 by the double-side flapper mechanism 112 (step 20). step 21).

  As described above, the transfer material S2 re-conveyed in the reverse conveyance path 101 and the double-side conveyance path 102 is eventually retransmitted to the registration roller 221 and a toner image is formed on the second surface (step 22). The transfer material S2 onto which the unfixed toner image (non-glossy or low-gloss image) is transferred on the second surface is sent again to the fixing device 1 by the transfer conveyance device 222. During this time, the controller instructs the voltage application of the halogen heater 2-1 of the heating roller 2 that drives the belt body 5 (step 23). Thus, the unfixed toner image on the second surface of the transfer material S2 is melted by the heat amount and pressure of the fixing device 1 and fixed as a permanent toner image. At this time, the first fixed toner image on the first surface, which has been normally fixed, is pressed again while being melted on the belt body side, so that a smooth and high-gloss image is fixed (step 23).

  That is, in the high-gloss surface side output in the special output mode, as shown in FIG. 3A, the toner image is heated and melted in the first fixing and is buried in the surface of the image receiving layer 52 for a while. Although the toner image Ta slightly protrudes from the surface (toner image Ta), as shown in FIG. 3b, the toner image T1 after the first fixing is almost completely buried in the image receiving layer 52 in the second fixing and the surface is smooth. The state (toner image Tb) is obtained. As shown in FIG. 2, the image receiving layer 52 of the transfer material S <b> 2 melted by being heated and pressed by the heating rolls 2 and 6 in the fixing device 1 and the image receiving layer 51 are also melted and pressed. Since the toner image Ta after the first fixing is cooled by the cooling device 7, the entire surface of the image receiving layer 52 including the toner image Ta is solidified in a smooth surface state following the surface of the belt body 5. It is. As a result, it is possible to form a photographic image (toner image Tb) with high gloss.

  Thus, the transfer material S2 having the toner image fixed on both sides thereof by the discharge roller 205 is discharged out of the image forming apparatus 200 (Step 24). Finally, the controller instructs the stop of various motors / heaters etc. (step 25), and ends the control sequence. As a result, a high gloss image is formed on one side of the transfer material S2, and a non-gloss or low gloss image is formed on the other side. In the case of this double-sided output, since the fixing process at the time of total image formation is only to pass through the fixing device 1 only twice, there is no time loss as in the case of passing through a plurality of fixing devices, and relatively. A fast double-sided image formation is possible, and a low-power and compact image forming apparatus is realized.

  As a result, images are formed on both surfaces of the gloss output transfer material S2. In particular, in this case, a high gloss image is formed on the surface having the image receiving layer 52, but there is no image receiving layer 52. A non-glossy or low-gloss image is formed on the surface. Such double-sided output in the special output mode, for example, when creating a postcard with a photo such as a New Year's card, forms a high-gloss image including a photo on one side, while addressing the other side, The present invention can be applied to applications such as forming non-glossy or low-gloss images such as shooting information.

  Subsequently, returning to (Step 19), if the single-sided output mode is instructed in the special output mode consisting of a high gloss image, the controller does not discharge the transfer material S2 as it is by the discharge roller 205. Even when the transfer material S2 is instructed to form an image in the single-side mode, the controller reversely conveys to the reverse conveyance path 101 by the reverse flapper mechanism 111 (step 27), and then conveys to the double-sided path 102 by the double-side flapper mechanism 112. (Step 28).

  In this way, the transfer material S2 re-conveyed in the reverse conveyance path 101 and the double-sided conveyance path 102 is eventually retransmitted to the registration roller 221, but unlike the double-sided case, a toner image is formed on the second surface of the transfer material S2. I do not image. The transfer material S2 that has passed through the transfer portion as it is is sent again to the fixing device 1 by the transfer conveying device 222. During this time, the controller instructs the voltage application of the halogen heater 2-1 of the heating roller 2 that drives the belt body 5 (step 29). In this way, the first-side fixed toner image once normally fixed on the transfer material S2 is pressed again while being melted on the belt body side, so that a smooth and high-gloss image is fixed (step 30).

  In this way, the transfer material S2 on which the smooth glossy toner image is fixed on the image receiving layer 52 side by the discharge roller 205 is discharged out of the image forming apparatus 200 (Step 31). Finally, the controller gives an instruction to stop various motors / heaters (step 32), and ends the control sequence. As a result, a high gloss image is formed on one surface of the transfer material S2. In the case of this single-sided output, it is not necessary to pass through the separate fixing devices once as in the image forming apparatus shown in the conventional example, but only passes through the fixing device 1 twice. There is no increase in installation space as in passing through the apparatus and no increase in cost, and a low-power and compact image forming apparatus is realized.

  As described above, according to the image forming apparatus of the present embodiment, image output on both sides of the recording sheet can be performed by one image forming unit 202, and therefore, double-sided output for forming a high gloss image on one side is possible. A compact and low-cost image forming apparatus can be provided.

  Further, as shown in the conventional example, it is not necessary to add mechanism units to the image forming apparatus one after another, which increases the cost, increases the installation size, and lengthens the recording sheet conveyance path. Initial productivity (F-COT: first copy time) is no longer inferior. In detail, not only when forming a double-sided image but also when forming a single-sided image of normal image quality, the recording sheet always passes through a path including a fixing path in which the recording sheets are arranged in series or a conveyance path that bypasses one of the fixing units. Since the recording sheet conveyance path configuration can be simplified instead of such a complicated configuration, productivity can be improved, the installation area can be reduced, and the cost can be reduced.

  In fact, it can be installed compactly to obtain a high-gloss image in the form of a silver salt photograph, even at a copy shop where there is a request for printing on the back side of a high-gloss silver salt photograph. It has become possible to provide a popular image forming apparatus that can perform printing.

  In this way, a compact image forming apparatus can be provided at low cost, which can satisfactorily perform double-sided image formation that forms a high-gloss image on at least one side of a recording sheet and forms a non-glossy or low-gloss image on the other side. It was.

Main cross section of multicolor image forming device Main section of fixing device 2A and 2B are diagrams illustrating a glossy output recording sheet fixing process state, in which FIG. 3A is a schematic cross-sectional view illustrating a state after one-time fixing, and FIG. Block diagram explaining the fixing device control system Flowchart for explaining fixing device control contents Main sectional view of a conventional multicolor image forming apparatus

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Fixing device 2, 6 Heating roller 3 Peeling roller 4 Steering roller 5 Belt body 7 Cooling device 101, 102 Transport path 111, 112 Flapper mechanism

Claims (3)

Heating an image forming means for forming an image on a recording material, a fixing rotator for thermally fixing an image on a recording material at a nip portion, and first heating means for heating the fixing rotator, an image on a recording material a belt member for conveying the recording material with the nip for forming said fixing rotary body, a second heating means for heating the belt member, the downstream side of the nip portion in the rotational direction of said belt member a separation roller for separating the recording material on the belt member from the belt member, a cooling means for cooling the area of the belt member of the separation roller upstream from the downstream side of the nip portion in the rotational direction of said belt member In an image forming apparatus capable of forming images on both sides of a recording material,
The belt member and the fixing rotator to the recording material having an unfixed toner image formed on the recording material is conveyed to the fixing on the recording material by heat in contact with the fixing rotary member by said image forming means And are arranged,
When a high-gloss image is formed on one side of the recording material and a low-gloss image is formed on the other side, the image formed on one side of the recording material is fixed by the fixing rotator , The image formed on the other surface with the front and back reversed is fixed on the recording material by the fixing rotating body heated by the first heating means at the nip portion so as to form a low gloss image, and formed on one surface. The formed image is fixed on the recording material by the belt member heated by the second heating means at the nip portion to form a high gloss image,
When low-gloss images are formed on both sides of the recording material, the image formed on one side of the recording material is fixed by the fixing rotator, and then the front and back sides of the recording material are reversed and formed on the other side. The image is fixed on the recording material by the fixing rotating body heated by the first heating unit at the nip portion, and the image formed on one surface is in a state where the energization to the second heating unit is stopped. An image forming apparatus, wherein the image forming apparatus is in contact with the belt member . When forming a high-gloss image on only one side of the recording material, after fixing the image by the fixing rotator, by introducing a recording material by reversing the nip, the high glossy image in said belt member Fixed to form
2. The image forming apparatus according to claim 1, wherein when a low gloss image is formed only on one surface of the recording material, the fixing rotating body performs fixing so as to form a low gloss image.   3. The image according to claim 1, wherein when the recording material is resin-coated paper, a high-gloss image is formed on the resin-coated side and a low-gloss image is formed on the opposite side. Forming equipment.

Images