JP2010066400A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve a problem that it is difficult to obtain a high gloss image because adhesiveness of fixing member and a toner image is low when the toner image is formed on pre-printing paper. <P>SOLUTION: The image forming apparatus has a smoothness adjusting means for lowering smoothness of a color toner image which has been previously fixed on recording material. The image forming apparatus forms a transparent toner image so as to superimpose on the color toner image after lowering the smoothness of the color toner image which has been previously fixed on the recording material. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus capable of forming a transparent toner image on a recording material on which a colored toner image has been heated and fixed in advance so as to overlap the colored toner image.

  In recent years, electrophotographic image forming apparatuses are also required to form highly glossy images such as silver salt photographs.

In Patent Document 1, a yellow, magenta, cyan, and black colored toner image formed on an intermediate transfer member and a transparent toner image are collectively transferred to a recording material, and then a fixing member is heated and fixed at a fixing nip portion. A high gloss image is formed.
JP-A-8-220821

  However, in order to increase the gloss of the color toner image heat-fixed on the recording material by another image forming apparatus, an unfixed transparent toner image is formed on the heat-fixed color toner image to be heat-fixed. However, the desired high gloss image could not be obtained.

  The cause is considered as follows. That is, in the step of heat-fixing the toner image on the recording material, the fixing member for heating the toner image and the unfixed toner on the recording material are brought into close contact with each other at the fixing nip portion, thereby smoothing the toner image and producing a high gloss image. obtain. At this time, the air existing between the unfixed toners hinders the fixing member from coming into close contact with the toner, but the air escapes from the fixing nip portion through the gap between the unevenness of the recording material surface and the toner. The fixing member can be in close contact with the toner.

  However, when the toner image is fixed in advance, the surface of the recording material is covered with the fixed toner image and is smooth, and this air remains in the fixing nip portion. For this reason, the fixing member and the unfixed toner cannot be brought into close contact with each other, and the surface of the toner image is not smoothed. As a result, high glossiness cannot be achieved.

  In the present invention, a transparent toner image forming means for forming an unfixed transparent toner image on a recording material on which a colored toner image is fixed in advance so as to overlap the colored toner image, and a recording material formed on the recording material. An image forming apparatus having a fixing means for fixing an unfixed transparent toner image to a recording material by heating at the nip portion has a smoothness adjusting means for reducing the smoothness of the colored toner image fixed in advance on the recording material. Then, after the color toner image fixed in advance on the recording material is lowered, a transparent toner image is formed so as to overlap the color toner image.

  According to the present invention, when an unfixed transparent toner image is formed on a recording material on which a colored toner image has been heated and fixed in advance so as to overlap the colored toner image, the degree of adhesion between the fixing member and the toner image is increased. It becomes possible to make it high, and a highly glossy image can be obtained.

  Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.

[Overall configuration of image forming apparatus]
FIG. 1 is a schematic view showing the entire image forming apparatus to which the present invention is applicable. The image forming apparatus 1000 is a color complex machine having a copying function using an intermediate transfer member and a printer function.

  An image reading unit 300 and an operation unit 400 are disposed on the upper surface of the apparatus main body 100. The image reading unit 300 optically scans a document placed on a platen glass and reads a document image by color separation photoelectric. The image information of the document read by the image reading unit 300 is subjected to image processing, and the exposure units 11 for each color are controlled in accordance with the image processed data. The operation unit 400 performs image formation mode setting and instruction input from the user, apparatus status notification to the user, and the like. On the basis of information signals of settings and instructions from the user, the control device 500 configured by a central processing unit (CPU) or the like integrates an image forming system including various process devices related to image formation, a fixing device, and the like. Control.

  Further, in the apparatus main body 100, five image forming portions Pa, Pb, Pc, Pd, and Pe for forming toner images are provided side by side in a substantially horizontal direction, and exposure apparatuses 11a, 11b, 11c, and 11d are disposed on the upper side thereof. 11e. An intermediate transfer belt 30 is disposed below the image forming portions Pa, Pb, Pc, Pd, and Pe.

  A feeding cassette 80 in which the recording material S is accommodated is disposed below the intermediate transfer belt 30 mechanism. A manual feed tray 2 is disposed on the side surface of the apparatus main body 100, and a paper feed deck 600 for accommodating a large amount of recording paper S is disposed below the manual feed tray 2. A fixing device 50 that heats and fixes a toner image formed on the recording material S is disposed downstream of the intermediate transfer belt 30 in the recording material conveyance direction. Further, before the secondary transfer portion T2 where the toner image on the intermediate transfer belt 30 is secondarily transferred to the recording material S, the surface of the toner image that is preliminarily heated and fixed on the recording material S is roughened to improve the smoothness. A smoothness adjusting roller 61 is provided as a pressure contact member to be lowered. Hereinafter, the recording material S on which the toner image is fixed in advance is particularly referred to as preprinted paper.

(Configuration of image forming unit)
As shown in FIG. 1, in the apparatus main body 100, five image forming portions Pa, Pb, Pc, Pd, and Pe are arranged in parallel. Here, the image forming portions Pa, Pb, Pc, and Pd that use yellow Y, magenta M, cyan C, and black Bk toner that are color toners, and the image forming portion Pe that uses transparent T toner that is a transparent toner are arranged in parallel. The provided structure is illustrated.

  The first to fifth image forming portions Pa, Pb, Pc, Pd, and Pe have the same configuration except for the color of the toner used. That is, each of the image forming units has photosensitive drums 1a, 1b, 1c, 1d, and 1e as image carriers.

  In addition, primary chargers 22a, 22b, 22c, and 22d, and exposure devices 11a, 11b, 11c, and 11d are provided around the photosensitive drums 1a, 1b, 1c, 1d, and 1e. Further, developing units 23a, 23b, 23c, 23d, and 23e, drum cleaners 12a, 12b, 12c, 12d, and 12e are provided.

  The developing units 23a, 23b, 23c, 23d, and 23e of each image forming unit are filled with yellow Y, magenta M, cyan C, and black Bk color toners and transparent T transparent toner, respectively.

  Further, an intermediate transfer belt 30 as an intermediate transfer member is rotatably installed so as to be in contact with the photosensitive drums 1a, 1b, 1c, 1d, and 1e. The intermediate transfer belt 30 is stretched around a driven roller 25, a secondary transfer counter roller 29, and a driving roller 26 driven by a driving motor. Then, primary transfer rollers 24a, 24b, 24c, 24d, and 24d are provided at positions opposed to the photosensitive drums 1a, 1b, 1c, 1d, and 1e, respectively, with the intermediate transfer belt 30 interposed therebetween. The driven roller 25 also serves as a tension roller and has a function of applying a predetermined tension to the intermediate transfer belt 30. The secondary transfer counter roller 73 is disposed opposite to a secondary transfer roller 9 described later with the intermediate transfer belt 30 interposed therebetween. The secondary transfer counter roller 9 is in contact with the intermediate transfer belt 30 to form a secondary transfer portion T2 for secondary transfer of the toner image on the intermediate transfer belt 30 to the recording material S. The secondary transfer counter roller 29 is configured to be applied with a secondary transfer bias from a high voltage power source during secondary transfer.

  Here, a transparent toner image forming unit is configured by the image forming unit Pe including the transparent toner, the intermediate transfer belt 30, the secondary transfer transfer roller 9, and the secondary transfer counter roller 29.

  Further, below the intermediate transfer belt 30, a paper feed cassette 80 that stores and stores recording materials is installed. A manual feed tray 2 is provided on the side surface of the apparatus main body 100. The recording material S fed from any one of the paper feed cassette 80, the manual feed tray 2, and the paper feed deck 600 by a pickup roller (not shown) is transported toward the smoothness adjusting roller pair 60 through a plurality of transport roller pairs 9. .

  In addition, an operation unit 400 is provided as an information acquisition unit for inputting whether or not the recording material S stored in the paper feed cassette 80, the manual feed tray 2, and the paper feed deck 600 is preprinted paper.

(Configuration of fixing device)
Here, the configuration of the fixing device 50 provided in the apparatus main body 100 will be described in detail with reference to FIG. In the fixing device 50, the fixing roller 51 and the pressure roller 52 are rotatably supported by bearings. The fixing roller 51 has a concentric three-layer structure, and has a core portion, an elastic layer, and a release layer from the inside. The core portion is composed of an aluminum hollow pipe having a diameter of 44 mm and a thickness of 5 mm. The elastic layer is made of silicon rubber having a JIS-A hardness of 50 degrees and a thickness of 2.5 mm. The release layer is made of PFA having a thickness of 50 μm. A halogen lamp H1 as a heat source (roller heater) is disposed inside the hollow pipe of the core portion.

  Similarly to the fixing roller 51, the pressure roller 52 has a three-layer structure including a core portion, an elastic layer, and a release layer from the inside. However, silicon rubber with a thickness of 3 mm is used for the elastic layer. This is to widen the width of the fixing nip portion by the elastic layer. Inside the hollow pipe of the core portion of the pressure roller 52, a halogen lamp H2 is disposed as a heat source (roller heater).

  The fixing roller 51 and the pressure roller 52 are pressed against each other with a predetermined pressing force to form a fixing nip portion N as a heating and pressure portion having a predetermined width in the recording material conveyance direction. The pressure applied by the pressure roller 52 was 588 N (60 kgf) in total pressure. At this time, the width of the fixing nip N in the conveyance direction of the recording material S was 7 mm.

  The fixing roller 51 and the pressure roller 52 are rotationally driven while being pressed against each other in the direction of the arrow by the drive motor M1. The heater H1 and the heater H2 are supplied with electric power from the power source E1 and the power source E2, respectively, and generate heat. The fixing roller 51 and the pressure roller 52 are heated from the inside by the heat generated by these heaters. An 800 W heater was used for the fixing roller 51 and a 500 W heater was used for the pressure roller 52. Then, the surface temperatures of the fixing roller 51 and the pressure roller 52 are monitored by a temperature sensor TH1 and a temperature sensor TH2 such as a thermistor that are in contact with each other. Based on the electrical information regarding the detected temperature, it is input to the controller 500.

  Based on the input information, the controller 500 controls the heaters H1, E2 from the power supply circuits E1, E2 so that the surface temperatures of the fixing roller 51 and the pressure roller 52 are maintained at a predetermined control temperature (fixing temperature). The power supplied to H2 is controlled. That is, the temperature of the fixing roller 51 and the pressure roller 52 are controlled to a predetermined temperature, and the temperature of the fixing nip portion is controlled to a predetermined fixing temperature. In this embodiment, the fixing temperature of the fixing roller 51 is set to 180 ° C., the fixing temperature of the pressure roller 52 is set to 150 ° C., and the temperature is adjusted by the control unit 500 so as to maintain this. Here, with reference to FIG. 7, a circuit for performing the control of the present embodiment will be described. The CPU of the control unit 500 performs control according to a control program stored in the ROM.

  The controller 500 is connected to temperature sensors TH1 and TH2 and power sources E1 and E2, and controls the temperature of the fixing roller 51 and the pressure roller 51.

  Further, the operation unit 400 and the motor M3 are connected to the control unit 500, and the operation of the smoothness adjusting roller pair 60 is controlled. The smoothness adjusting roller pair 60 will be described in detail later. Further, the control unit 500 as a control unit is also connected to the image forming units Pa, Pb, Pc, Pd, and Pe, and also controls image formation.

  The web-type cleaning device 53 and the surface of the fixing roller 51 are wiped and cleaned. The web type cleaning device 54 wipes and cleans the surface of the pressure roller 52. The webs of the cleaning devices 53 and 54 are heat resistant cleaning members.

  The fixing roller 51 and the pressure roller 52 are rotationally driven, and the rollers 51 and 52 are heated from the inside by the heaters H1 and H2, respectively, so that the surface temperature becomes a predetermined control temperature. .

  In this state, the recording material S on which the unfixed toner image is formed by the conveyance belt is introduced from the intermediate transfer belt mechanism side into the fixing nip portion N of the fixing device 50. In the process of entering the fixing nip portion N and being nipped and conveyed, the fixing roller 51 and the pressure roller 52 are heated and pressed by the nip pressure. As a result, the toner image in which the toners of five colors of yellow, magenta, cyan, black, and transparent are overlapped is melted and mixed and fixed on the surface of the recording material S as a full color image. The recording material P that has come out of the fixing nip N is separated from the fixing roller 51 or the pressure roller 52 by a separation claw (not shown) and sent out from the fixing device 50.

(Smoothness adjustment roller)
Here, with reference to FIG. 2, the structure of the smoothness adjusting roller pair 60 as the smoothness adjusting means, which is a feature of the present invention, will be described in detail. The smoothness adjusting roller pair 60 includes a protruding roller 61 and a rubber roller 62. FIG. 3 shows a schematic view of the protrusion of the protrusion roller 61. The rubber roller 62 uses silicon rubber as an elastic body excellent in surface smoothness, and has a length of 360 mm and a diameter of 25 mm. The protrusion roller 61 is a SUS metal roller having a length of 360 mm and a diameter of 20 mm, and a plurality of conical convex portions having a height h = 30 μm and a diameter R = 100 μm are continuously formed at a pitch of 500 μm on the surface layer. positioned. In this example, the projections were formed by a so-called blast roller manufacturing method in which abrasive grains were sprayed onto the surface with a constant pressure to give a large number of irregularities and the surface roughness Rz could be about 10 to 20 μm. In addition, although the convex part in a present Example used the cone-shaped thing as shown to Fig.3 (a), for example, as shown to a figure (b) and (c), a cross section has a long shape or a trapezoid shape. It doesn't matter if it's part. Further, in this embodiment, the material of the convex portion of the surface layer portion is alumina-based abrasive grains, but it has a sufficiently high hardness with respect to the toner layer, has excellent cutting properties, and lowers the smoothness of the toner image surface. If possible, the present invention is not limited to this. If the above conditions are satisfied, a wrapping film or sandpaper can be wound around a metal core to form a convex portion on the surface layer of the roller.

  As shown in FIG. 2A, the protrusion roller 61 and the rubber roller 62 are rotatably supported by bearings, respectively, and receive a driving force from the motor M2 in the recording material conveyance direction indicated by arrows Y1 and Y2 in the drawing. Rotate. Further, the protrusion roller 61 and the rubber roller 62 can be brought into contact with and separated from the recording material S in order to adjust the smoothness of the recording material S. At this time, the contact / separation operation is performed by rotating the contact / separation cam 63 as the contact / separation mechanism by the contact / separation motor M3. As shown in FIG. 2B, when the contact / separation cam 63 rotates clockwise and pushes down the shaft 611 of the protruding roller 61, the protruding roller 61 comes into contact with the recording material S to be conveyed and is on the surface layer portion thereof. By allowing the protrusions to enter the surface of the recording material S, the smoothness can be lowered. As shown in FIG. 2C, when the contact / separation cam 63 rotates clockwise to push up the shaft 611, the protruding roller 61 is separated from the recording material S and the rubber roller 62 to be conveyed. By having the contact / separation mechanism in this way, when an image is formed on the recording material S that is not preprinted paper, the smoothness adjusting roller pair 60 is turned off and separated so as not to make unnecessary holes. can do. That is, the operation state of the parallelism adjusting roller pair 60 is changed depending on whether or not the recording material S is preprinted paper.

  Further, the protruding roller 61 and the rubber roller 62 can be pressed against each other with a predetermined pressure. In this embodiment, the protruding roller 61 is spring-pressed at both ends with a total pressure of 20 kgf against the rubber roller 62. By operating the smoothness adjusting roller pair 60, as shown in FIG. 2, the protruding portion of the protruding roller 61 enters the toner image of the preprinted paper, and the smoothness can be lowered.

The smoothness of the preprinted paper used in this embodiment is about 276 seconds when measured with a Beck smoothness meter manufactured by Kumagai Riki Kogyo Co., Ltd. (according to a smoothness test method using JIS P 8119 paper and paperboard Beck tester). Met. When the above-described smoothness adjusting roller pair 60 was rotated and this preprinted paper was nipped and conveyed by the protrusion roller 61 and the rubber roller 62, the smoothness of the preprinted paper was 195 seconds. In this embodiment, the image forming apparatus 100 is used to form a preprint paper by forming a blue image of cyan 100% magenta 100% on a plain paper 80 gsm paper at a loading amount of 0.5 mg / cm ² . . The toner thickness at this time was about 12 μm.

  That is, the smoothness of the toner image on the preprinted paper is lowered by performing the punching process on the toner image fixed on the preprinted paper using the smoothness adjusting roller pair 60. In this way, by lowering the smoothness of the toner image on the preprinted paper, the transparent toner formed on the preprinted paper on the preprinted paper in the subsequent step is favorably fixed.

  The smoothness of the preprinted paper has a great influence on multiple fixing in which a toner image is further formed on the surface of the preprinted paper on which the toner image is fixed and heat fixing is performed. FIG. 4 shows a state in which the pre-printed paper SA on which the colored toner L is fixed and the fixing roller 51 are close to each other when performing multiple fixing. FIG. 4 shows a state after the transparent toner T is transferred to the preprinted paper SA. When the transparent toner T is fixed in contact with the fixing roller 51, if the colored toner L is already fixed and the smoothness is high as in preprinted paper, the air existing between the unfixed transparent toner T is fixed. It becomes difficult to escape from the nip portion N.

  As a result, the transparent toner T cannot adhere to the surface of the fixing roller 51, resulting in low gloss. Therefore, as in the present embodiment, the toner image of the preprinted paper is roughened by the protrusion roller 61 and the smoothness is lowered, so that the air escapes from the fixing nip portion N so that the fixing roller 51 and the transparent toner T are in close contact with each other. I am letting.

  In this embodiment, when the smoothness adjustment is performed by the smoothness adjustment roller pair 60 to reduce the smoothness of the toner image on the preprint paper, the transparent toner is fixed, and the glossiness of the transparent toner image after heat fixing is measured. The 60 ° gloss was 20.1. As a result, it was confirmed that the degree of gloss was significantly increased as compared with the 60 ° glossiness of 4.0 when smoothness adjustment was not performed. In addition, glossiness was measured using the Nippon Denshoku Industries Co., Ltd. handy type gloss meter (based on JISZ8741 specular glossiness-measuring method).

  In the present embodiment, from the viewpoint that the image should not be whitish, the glossiness is required to be at least 10 or more, and this target is achieved by reducing the smoothness of the toner image of the preprint paper. Could be achieved.

However, if the hole is penetrated to the back side of the paper, the image quality on the back side is deteriorated. Therefore, a hole having a depth that does not penetrate the paper even though the toner penetrates is desired. Therefore, the height h of the convex portion needs to satisfy t ≦ h <d + t, where t is the toner layer thickness and d is the thickness of the recording material. Considering the case where a color image in which two solid toner images are superimposed is output, the thickness of the toner layer is about 10 μm. Considering the minimum basis weight of paper on which an image can be formed with an electrophotographic image forming apparatus, the paper has a thickness of about 64 g / m ² and a paper thickness of about 70 μm. Therefore, it is desirable that the height h of the convex portion is 10 μm or more and less than 70 μm.
Table 1 below shows the change in the smoothness of the preprinted paper when the diameter of the convex portion of the protrusion roller 61 is changed, the 60 ° glossiness of the fixed transparent toner portion, and image formation by the image forming apparatus 100. The result of having evaluated the image obtained by performing is shown.

  In this evaluation, preprinted paper was used on which a blue image having a cyan and magenta data amount of 100% was fixed. In addition, a transparent toner image having a transparent toner data amount of 100% was formed on the transparent toner portion. The relationship between the data amount and the applied toner amount will be described later.

  From FIG. 10, when the diameter of the convex portion is less than 50 μm, the hole is too small to allow bubbles to escape, so the smoothness cannot be lowered sufficiently and the gloss cannot be increased. On the other hand, when the diameter of the convex portion exceeds 200 μm, the hole is too large for the bubble and the smoothness is increased, but the gloss is not increased, the hole on the image surface is noticeable and the image quality is lowered. When the diameter of the convex portion was 50 μm or more and 200 μm or less, the smoothness decreased and a good image could be obtained. Therefore, the diameter of the convex portion of the protrusion roller 61 is desirably 50 μm or more and 200 μm.

  When improving the surface quality by making holes in preprinted paper, if the holes are located at a pitch more than 10 times the diameter of the holes, the air bubbles between the holes cannot be released. , Less glossy. Also, if the holes are positioned at a pitch that is twice or less the diameter of the holes, the image will be full of holes and the image quality will be reduced. Therefore, if the diameter of the convex portion is d, it is considered that a good image can be obtained when the pitch (interval) Sm of the convex portion is 2R ≦ Sm ≦ 10R.

  Table 2 below shows the change in the smoothness of the preprinted paper when the pitch of the convex portions of the protrusion roller 61 is changed, the 60 ° glossiness of the fixed transparent toner portion, and image formation by the image forming apparatus 100. The result of having evaluated the image obtained by performing is shown. In this evaluation, preprinted paper was used on which a blue image having a cyan and magenta data amount of 100% was fixed. In addition, a transparent toner image having a transparent toner data amount of 100% was formed on the transparent toner portion.

  At this time, the height of the convex portion is 100 μm. From Table 2, when the pitch (interval) is less than 200 μm, the number of holes increases with respect to the bubbles, so that the smoothness is increased but the gloss is not easily produced, and the holes on the image surface are conspicuous and the image quality is lowered. On the other hand, if the pitch exceeds 1.0 mm, the number of holes is insufficient with respect to the bubbles and it becomes difficult to obtain gloss. When the pitch was 200 μm or more and 1.0 mm or less, the smoothness decreased and a good image could be obtained. Therefore, when the height of the convex portion is 100 μm, the pitch of the convex portion of the protrusion roller 61 is preferably 200 μm or more and 1.0 mm or less.

  In order to allow protrusions to enter the fixed color toner layer, it is necessary to apply a certain pressure or more. When springs are installed at both ends of the smoothness adjusting roller and pressure is applied, when the total pressure of the spring is less than 1 kgf, the protrusions do not sufficiently enter and a hole that penetrates the toner layer does not open. On the other hand, when the total pressure of the spring exceeds 80 kgf, the conveyance of the recording material is deteriorated, and the recording material is wrinkled or broken. Therefore, when a spring is installed at both ends of the smoothness adjusting roller to apply a spring pressure, the total pressure P is preferably 1 kgf ≦ P ≦ 80 kgf.

When the range of the total pressure P is expressed by the pressure Ps, the width of the fixing nip portion N in the recording material conveyance direction is 7 mm and the length in the longitudinal direction is 360 mm.
0.4 × 10 ³ Kgf / m ² ≦ Ps ≦ 3.2 × 0 ⁴ Kgf / m ² Therefore, the preferable range of the pressure Ps is 0.4 × 10 ³ Kgf / m ² or more and 3.2 × 0 ⁴ Kgf / m ² or less.

(toner)
Next, the toner will be described. Here, a toner using a polyester resin is used as the toner. The toner can be produced by a pulverization method, but here, as a method for producing the toner, a method for producing the toner directly in a medium such as a suspension polymerization method, an interfacial polymerization method or a dispersion polymerization method (polymerization method). ) Is preferred. The toner components and the production method are not limited to these.

  The color toner contains 5% by weight of a low melting point wax.

  The transparent toner is a manufacturing method that is almost the same as the manufacturing method of the color toner and that does not include the step of adding the pigment component in the manufacturing process of the color toner. The main binder used was the same, and the amount of wax added and the formulation of the external additive were also the same.

  Although the resin characteristics of the toner slightly change depending on whether the pigment component is added or not, according to the color toner and the transparent toner as described above, the difference in the glass transition temperature Tg is 10 ° C. or less.

  Next, the toner amount will be described.

  As the image data input to the image forming unit, 600 dpi data 0 to 255 separated into C, M, Y, and K colors of the original image is input.

  This data per pixel is called an image data amount. The maximum amount of image data for each color is expressed as 100%. The amount of toner to be imaged is calculated according to the 0 to 100% image data amount.

The toner amount is the amount of toner per pixel on which an image is formed on a recording material. The toner amount is also represented by 0 to 100%, similarly to the image data amount. The weight of toner when an image is formed on 1 cm ² is referred to as an applied amount. When the toner amount is 100% for a single color, the maximum applied amount of the color is obtained and the maximum density is obtained. In the case of transparent toner, glossiness is an index, not density.

  The maximum density and glossiness are determined by image design, toner characteristics, fixing conditions of the fixing device (fixing device), the type of recording material, and the like.

In this embodiment, the maximum loading amount of the color toner and the transparent toner is 0.5 mg / cm ² . As for the glossiness at this time, when an image was formed with a transparent toner on an A2 gloss-coated paper having a basis weight of 150 g / m ² , a gloss of 40% was measured in a 60-degree gloss measurement with an applied amount of 0.5 mg / cm ^2. Got. The measuring method of gloss used the Nippon Denshoku Industries Co., Ltd. handy type gloss meter (PG-1M) (based on JISZ8741 specular glossiness-measuring method). Further, the toner height after fixing at a loading amount of 0.5 mg / cm ² is about 6 μm, and the toner height for two colors after fixing at the maximum loading amount for two colors is about 12 μm. It was.

(Image formation mode)
Here, an image forming mode that can be executed by the image forming apparatus 1000 of the present embodiment will be described with reference to FIG. The image forming apparatus 1000 according to this embodiment includes a five-color mode in which image formation is performed with Y, M, C, K, and T toners, and a four-color mode in which image formation is performed with only Y, M, C, and K colored toners A transparent mode in which an image is formed using only the transparent toner T can be executed.

  First, an image forming operation diagram in the five-color mode will be described.

  When an image formation start signal is received from the control unit 500, the first to fifth image forming units Pa, Pb, Pc, Pd, Pe are sequentially driven at a predetermined control timing. By the drive, the photosensitive drums 1a, 1b, 1c, 1d, and 1e of each image forming unit rotate counterclockwise and are charged by the primary chargers 22a, 22b, 22c, 22d, and 22e, respectively. Subsequently, in response to the image information signal, the exposure devices 11a, 11b, 11c, 11d, and 22e expose the photosensitive drums 1a, 1b, 1c, 1d, and 1e to form electrostatic images. The electrostatic images on the photosensitive drums 1a, 1b, 1c, 1d, and 1e are developed by developing units 23a, 23b, 23c, and 23d, respectively.

  Here, a yellow toner image of a full-color image is formed on the peripheral surface of the drum 1a of the first image forming unit Pa by the electrophotographic process operation as described above. A magenta toner image of a full color image is formed on the peripheral surface of the drum 1b of the second image forming unit Pb. A cyan toner image of a full color image is formed on the peripheral surface of the drum 1c of the third image forming unit Pc. A black toner image of a full color image is formed on the peripheral surface of the drum 1d of the fourth image forming unit Pd. A transparent toner image is formed on the peripheral surface of the drum 1e of the fifth image forming unit Pe. The toner images formed on the photosensitive drums 1a, 1b, 1c, 1d, and 1e are sequentially superposed on each color toner image by applying a primary transfer voltage to the primary transfer rollers 24a, 24b, 24c, 24d, and 24e. In this way, primary transfer is performed on the intermediate transfer belt 30.

  On the other hand, the recording material S is selectively separated and fed one by one from any one of the feeding cassette 80, the manual feed tray 2, and the paper feed deck 600. Then, when the recording material S is pre-printed paper, the smoothness is lowered by the smoothness adjusting roller pair 60 and then conveyed toward the registration roller 3 through a plurality of conveying roller pairs 9. On the other hand, when the recording material S is not pre-printed paper, the protrusion roller 61 is separated from the rubber roller 62 and is conveyed toward the registration roller 3 without performing a punching process. The registration roller 3 sends out the recording material S so that the timing at which the toner image on the intermediate transfer belt 30 enters the secondary transfer portion T2 matches the timing at which the recording material S enters the secondary transfer portion T2. It has a function to control timing.

  Subsequently, a secondary transfer bias is applied to the secondary transfer counter roller 29, and the toner image on the intermediate transfer belt 30 is secondarily transferred collectively to the recording material S fed to the secondary transfer portion T2. The recording material S to which the color image is transferred in this way is conveyed toward the fixing device 50. The intermediate transfer belt 30 after the secondary transfer is cleaned by the cleaning device 21.

  The recording material S on which the toner image is secondarily transferred is introduced into the fixing device 50. The recording material P introduced into the fixing device 50 enters the fixing nip portion N which is a pressure contact portion between the fixing roller 51 and the pressure roller 52 and is nipped and conveyed, whereby the recording material S is heated and pressed. Thus, the color toner images are mixed and fixed on the recording material P.

  Next, the 4-color mode will be described.

  When an image formation start signal is received from the control unit 500, the image forming units Pa, Pb, Pc, Pd are sequentially driven in accordance with a predetermined control timing. At that time, the image forming unit Pe is stopped. In each of the YMCK image forming portions Pa, Pb, Pc, and Pd, YMCK toner images are formed on the photosensitive drums 1a, 1b, 1c, and 1d, respectively, in the same manner as in the five-color mode, and the primary transfer is performed on the intermediate transfer belt 30. Is done. Then, the toner image on the intermediate transfer belt 30 is transferred to the recording material S conveyed from any one of the feed cassette 80, the manual feed tray 2 and the paper feed deck 600 to the secondary transfer portion T2 through the registration roller 3. Next is transferred. Even in the four-color mode, when the recording material S conveyed to the secondary transfer portion T2 is preprinted paper, the smoothness adjustment is lowered by the smoothness adjustment roller pair 60 and then conveyed toward the registration roller 3. The On the other hand, when the recording material S is not pre-printed paper, the protrusion roller 61 is separated from the rubber roller 62 and is conveyed toward the registration roller 3 without performing a punching process. The recording material S separated from the intermediate transfer belt 30 is conveyed to the fixing device 50, and the toner image to be heated and pressed is fixed.

  Next, the transparent mode will be described.

  When an image formation start signal is received from the control unit 500, the image forming unit Pe of the transparent toner T is driven in accordance with a predetermined control timing. At that time, the color toner image forming portions Pa, Pb, Pc, and Pd are stopped. In the image forming unit Pe, a transparent toner image is formed on the photosensitive drum 1e and is primarily transferred to the intermediate transfer belt 30 in the same manner as in the five-color mode. Then, the toner image on the intermediate transfer belt 30 is transferred to the recording material S conveyed from any one of the feed cassette 80, the manual feed tray 2 and the paper feed deck 600 to the secondary transfer portion T2 through the registration roller 3. Next is transferred. Even in the transparent mode, when the recording material S conveyed to the secondary transfer portion T2 is preprinted paper, the smoothness is lowered by the smoothness adjusting roller pair 60 and then conveyed toward the registration roller 3. On the other hand, when the recording material S is not pre-printed paper, the protrusion roller 61 is separated from the rubber roller 62 and is conveyed toward the registration roller 3 without performing a punching process. The recording material S separated from the intermediate transfer belt 30 is conveyed to the fixing device 50, and the toner image to be heated and pressed is fixed.

  Here, a method for forming images on both sides of the recording material S in the five-color mode, the four-color mode, and the transparent mode will be described.

  When a toner image is formed only on one side of the recording material S, the recording material S on which the toner image is fixed by the fixing device 50 is conveyed to the paper discharge tray 4 and the image formation is completed. On the other hand, when a toner image is formed on the opposite surface of the recording material S, the recording material S on which the toner image is fixed on the first surface by the fixing device 50 is again transferred to the secondary transfer portion by the refeed path 5. Transported to T2. When the recording material S is preprinted paper, the above-described five-color mode, four-color mode, and transparent are applied to the second surface, which is the back surface of the first surface, through the perforation processing by the smoothness adjusting roller pair 60. A toner image is formed in any of the modes.

  A path for discharging the recording material S to the discharge tray 4 after fixing and a path for feeding the recording material S to the secondary transfer portion T2 again will be described.

  A selector 10 serving as a conveyance path switching unit for the recording material S is installed downstream of the fixing device 50 in the recording material conveyance direction. The selector 10 can switch the conveyance direction of the recording material S between a position (a) for discharging the recording material S out of the apparatus main body 100 and a position (b) for refeeding to the secondary transfer portion T2.

  When the toner image is formed on only one side of the recording material S, the recording material S on which the toner image is fixed by the fixing device 50 is transported in the direction of arrow A in the figure by the selector 10 switched to (a). 8 and discharged to the discharge tray 4 outside the apparatus main body 100.

  When toner images are formed on both sides of the recording material S, the recording material S on which the toner image has been fixed on the first surface by the fixing device 50 travels in the direction of arrow B by the selector 10 switched to (b). It is changed and conveyed to the conveyance path 7. Then, the reverse path (switchback path) 6 positioned downstream of the transport path 7 in the recording material transport direction is transported in the direction of arrow C and reversed upside down, and then sent to the refeed path 5. The reversed recording material S is conveyed to the smoothness adjusting roller pair 60 through the refeed path 5. When the recording material S is preprinted paper, the toner image on the second surface is subjected to a hole punching process by the smoothness adjusting roller pair 60 and then conveyed to the registration roller 3. The registration roller 3 is fed again to the secondary transfer portion T2 with the second surface facing upward. Then, the YMCKT color toner image on the intermediate transfer belt 30 is transferred to the second surface of the recording material S. The recording material P to which the toner is transferred on the second side is conveyed to the fixing device 50, and the toner image is fixed on the second side. The recording material that has come out of the fixing device 50 is guided to the conveyance path 8 by the selector switched to (a) 10 and is discharged to the discharge tray 4 outside the apparatus.

  By the way, in the above-described five-color mode, unfixed YMCKT toner is fixed together. In this embodiment, first, a YMCK toner image is formed and fixed in the four-color mode, and then a transparent toner image is formed on the surface on which the YMCK toner image is formed in the transparent mode. Multiple fixing for fixing can be performed.

  When multiple fixing is performed, the color toner image can be heated twice, so that the glossiness of the area of the color toner image on which the transparent toner image is not superimposed can be made higher than in the 5-color mode.

  Here, the multiple fixing method will be described in detail. In order to prevent excessive repetitive heating, multiple fixing can be performed only on the recording material S that is not preprinted paper.

  When an image formation start signal is received from the control unit 500, the image forming units Pa, Pb, Pc, and Pd are sequentially driven in accordance with a predetermined control timing. At that time, the image forming unit Pe is stopped. In each of the YMCK image forming portions Pa, Pb, Pc, and Pd, YMCK toner images are formed on the photosensitive drums 1a, 1b, 1c, and 1d, respectively, and are primarily transferred to the intermediate transfer belt 30. Then, the toner image on the intermediate transfer belt 30 is transferred to the recording material S conveyed from any one of the feed cassette 80, the manual feed tray 2 and the paper feed deck 600 to the secondary transfer portion T2 through the registration roller 3. Next is transferred. After the secondary transfer, the toner image on the recording material S is fixed by the fixing device 50.

  The recording material S on which the YMCK colored toner image is fixed by the fixing device 50 is advanced in the direction of arrow B by the selector 10 switched to (b) and is guided to the conveyance path 7.

  The recording material S is not conveyed to the reversing path 6 and is guided to the refeed path 5 without being reversed. The recording material S is further conveyed to the smoothness adjusting roller 60, and the surface on which the colored toner image is fixed is punched.

  On the other hand, when the secondary transfer of the colored toner image is completed, the image forming unit Pe is driven to form a transparent toner image on the photosensitive drum 1e. At this time, the image forming portions Pa, Pb, Pc, and Pd are stopped. The transparent toner image on the photosensitive drum 1 e is primarily transferred to the intermediate transfer belt 30.

  The perforated recording material S is supplied to the secondary transfer portion T2 by the registration roller 3, and the transparent toner image is secondarily transferred onto the perforated surface. When the secondary transfer of the transparent toner image is completed, the recording material S is conveyed to the fixing device 50, and is discharged to the discharge tray 8 through the conveyance path 8 after fixing.

(Formation of image information signal of colored toner image and transparent toner image)
When the image forming apparatus 100 is used as a printer, it forms an image according to electrical image information input from an external host device (not shown) such as a PC (personal computer). Image information transmitted from the PC is converted into an image information signal by the image forming apparatus 1000. The exposure devices 11a, 11b, 11c, 11d, and 11e expose the photosensitive drums 1a, 1b, 1c, 1d, and 1e based on the image information signals to form electrostatic images.

  When image formation is performed in the four-color mode, the YMCK four-color image formed by the user is converted into four-color image information of YMCK by an external PC and then transmitted to the image forming apparatus 1000. The transmitted image information is converted by the image forming apparatus 100 into image information signals for exposure of the exposure apparatuses 11a, 11b, 11c, 11d, and 11e.

  Similarly, when image formation is performed in the five-color mode, the YMCK and transparent five-color image formed by the user are converted into YMCK and transparent five-version image information on an external PC, and then the image forming apparatus 1000. Here, the formation of YMCK and a transparent five-color image and the conversion of the image into five-version image information can be performed by Photoshop (registered trademark) manufactured by Adobe Systems Incorporated. The 5-plate image information is converted by the image forming apparatus 1000 into image information signals for exposure by the exposure apparatuses 11a, 11b, 11c, 11d, and 11e.

  When image formation is performed in the transparent mode, an image formed by the user as a color image such as black is converted to transparent image information by an external PC and then transmitted to the image forming apparatus 1000. The transmitted image information is converted by the image forming apparatus 1000 into an image information signal for exposure by the exposure apparatus 11e.

  Next, a method for forming an image formation information signal when the image forming apparatus 1000 is used as a copier will be described.

  A color original placed on the original table glass of the image reading unit 300 in FIG. 1 is scanned by a scanner that moves along the lower surface of the original table glass. The original scanning light is imaged on a CCD, which is a photoelectric conversion element (solid-state imaging element), and is color-separated and read with three primary colors of RGB (red, green, and blue). The read RGB signals are input to the control unit 500 and converted into image information signals for exposure by the exposure apparatuses 11a, 11b, 11c, 11d, and 11e.

  When the transparent image is drawn in black, it can be read by the document reading unit 300 after setting the mode for reading the transparent document as a black image by the operation unit 400.

  Hereinafter, a specific operation method of the operation unit 400 and the operation of the image forming apparatus 1000 associated therewith will be described in detail. FIG. 5 shows a schematic diagram of the operation screen, and FIG. 6 shows a flowchart of this embodiment.

  The user sets the paper type by setting the recording material S in any of the large-capacity feeding unit 600, the feeding cassette 80, and the manual feed tray 2. At this time, whether or not the recording material S is preprinted paper is set at the same time. As shown in FIG. 5A, a preprint button for designating whether or not preprinted paper is used is displayed on the printer driver screen displayed on the screen of the operation unit 400 or an external PC.

  When preprinted paper is used as the recording material S (S101, Yes), the smoothness of the recording material S is high because the toner image is already fixed. When a toner image to be newly formed is fixed, air is trapped in the fixing nip portion N to prevent contact between the toner and the fixing roller 51, and there is a possibility that gloss does not appear. For this reason, the toner image that has been fixed by the smoothness adjusting roller pair 60 is perforated and roughened so that air can easily escape from the fixing nip portion N, and a high gloss image can be obtained (S102). In accordance with the user's designation, the control unit 500 selects an image forming mode to be executed (S103), and a toner image is formed in any of four, five, and transparent modes (S103, S104, and S105).

  The recording material S on which the toner image is fixed is discharged to the paper discharge tray 4 (S118).

  When preprinted paper is not used as the recording material S (S101, NO), whether or not to perform multiple fixing is selected (S107).

When multiple fixing is selected (S107, YES), the protrusion roller 61 of the parallelism adjusting roller pair 60 is separated from the rubber roller 62 (S108). In this state, the four-color mode is executed (S109), and the YMCK toner image is secondarily transferred and fixed onto the recording material S on which the punching process has not been performed. The recording material S on which the YMCK toner image is fixed is conveyed toward the secondary transfer portion N via the refeed path 5 (S110). At this time, the protruding roller 61 is brought into contact with the rubber roller 62 (S111), and the surface on which the YMCK toner image is formed is punched in the previously performed four-color mode. When the secondary transfer of the YMCK toner image formed in the four-color mode is completed, the transparent mode is executed,
A transparent toner image is formed on the surface of the recording material S that has been punched (S112). The recording material S on which the transparent toner image is fixed is discharged to the paper discharge tray 4 (S118).

  Here, a setting method of the operation unit 400 when selecting multiple fixing will be described with reference to FIG.

  When the four-color mode is selected by the mode selection unit 401 in FIG. 5B, a “clear two-pass composition” button 401 for selecting whether to re-feed the recording material S and form a transparent toner image is displayed. Is displayed. When the “Clear 2-pass composition” button 401 is pressed to select formation of a transparent toner image, the transparent toner image to be formed can be selected as shown in FIG. 4C. The selectable transparent toner image can be stored in the apparatus main body 100 in advance by image data transmission from the PC or image reading by the image reading unit 300.

  By the way, when the preprinted paper is not used as the recording material S (S101, No) and the multiple fixing is not performed (S107, No), the protruding roller 61 is separated from the rubber roller 62.

  Then, according to the user's specification, the control unit 500 selects an image forming mode to be executed (S114), and a toner image is formed in any of four, five, and transparent modes (S115, S116, and S117). .

In this embodiment, when the toner image is formed and fixed on the recording material S after the perforation processing is performed by the smoothness adjusting roller pair 60 as described above, the glossiness of the transparent toner on the color toner image of the preprint paper is It was 20.1. As a result, the glossiness increased by about 15.6 as compared with the case where no drilling process was performed. As described above, in the present embodiment, the image forming apparatus 1000 is used to form blue images with cyan and magenta data amounts of 0.5 mg / cm ² on plain paper 80 gsm. Pre-printed paper. The toner thickness at this time was about 12 μm.

  As described above, with the above-described configuration, an image with high glossiness can be obtained even when a toner image is formed on preprinted paper. In the case of unused paper that is not preprinted paper, a high-quality image could be obtained without making a hole.

  In the present embodiment, a configuration having five image forming units has been illustrated, but the number of use is not limited, and may be set as necessary.

  In the present embodiment, a multifunction peripheral having a printer function and a copy function is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may have any one of a printer function, a copy function, and a facsimile function. Alternatively, in addition to the combinations described above, other image forming apparatuses that combine these functions may be used. The same effect can be obtained by applying the present invention to these image forming apparatuses.

  In this embodiment, an intermediate transfer member is used, and toner images of respective colors are sequentially transferred onto the intermediate transfer member, and the toner images carried on the intermediate transfer member are collectively transferred to a recording material. Although an apparatus was illustrated, it is not limited to this. For example, an image forming apparatus that sequentially superimposes and transfers toner images of each color onto a recording material carried on a recording material carrier may be used. The same effect can be obtained by applying the present invention to these image forming apparatuses.

  In this embodiment, the fixing device of the fixing roller pair is used. However, the present invention is not limited to this, and needless to say, the effect can be obtained by a fixing device using a fixing belt.

  In this embodiment, the transparent toner is used. However, the present invention is not limited to this, and it goes without saying that the effect can be obtained by using, for example, a gold or silver spot color toner.

  FIG. 8 schematically shows a schematic configuration of another image forming apparatus 2000 to which the present invention can be applied. FIG. 5 is a schematic diagram of the operation unit 400, FIG. 9 is a flowchart, and FIG. 10 is a block diagram of a circuit that performs control performed in the image forming apparatus 2000. Since the overall configuration of the image forming apparatus 2000 of the present embodiment is almost the same as that of the image forming apparatus 1000 shown in FIG. 1, the same parts as those of the image forming apparatus 1000 are denoted by the same reference numerals, and the description thereof is omitted. To do. Further, the same smoothness adjusting roller pair 60 as that of the first embodiment was used.

  Similar to the image forming apparatus 1000, the image forming apparatus 2000 includes a smoothness adjusting roller pair 60. The image forming apparatus 2000 according to the present embodiment and the first embodiment include the image detection mechanism 70 for detecting the presence / absence of an image on the recording material S on the recording material conveyance path on the upstream side in the recording material conveyance direction. This is a difference from the image forming apparatus 1000. The image detection mechanism 70 includes an image sensor 71 and a conveyance roller 72 disposed to face the image sensor 71.

  The image sensor 71 is a contact image sensor (hereinafter referred to as “CIS”). A conveyance roller 72 conveys the recording material S while being rotated, and the image sensor 71 scans the recording material S during the rotation. Based on the scanning result, the control unit 700 shown in FIG. 10 determines whether or not the recording material S is preprinted paper. If the recording material S is preprinted paper, the smoothing adjustment roller pair 60 performs punching processing. An image sensor 71 is connected to the control unit 700 as control means.

  Here, the flow of image formation in the present embodiment will be described with reference to FIG.

  The recording material S fed from any one of the large-capacity feeding unit 600, the feeding cassette 80, and the manual feeding tray 2 is scanned by the image sensor 71 (S201). The scanning result is sent to the control unit 700 in FIG. 10 and converted into a binary signal indicating the presence or absence of a colored region. The control unit 700 determines whether or not the recording material S fed from the binary signal is preprinted paper (S202).

  When the fed recording material S is determined to be preprinted paper (S202, Yes), and further, when multiple fixing is not selected (S203, NO), the protrusion roller 61 is brought into contact with the rubber roller 62 and punched. Processing is performed (S205).

  Then, according to the user's specification, the control unit 700 selects an image forming mode to be executed (S206), and a toner image is formed in any of four, five, and transparent modes (S207, S208, and S209). .

  The recording material S on which the toner image is fixed is discharged to the discharge tray 4 through the conveyance path 8 (S221).

  Further, when multiple fixing is selected (S203, Yes), in order to prevent the recording material S from being heated excessively, as shown in FIG. 5D, multiple fixing is selected on the operation unit 400. A warning to cancel is issued.

  On the other hand, in S202, it is determined that the fed recording material S is not preprinted paper (S202, No), and if multiple fixing is not selected (S210, No), the protrusion roller 61 is separated from the rubber roller 62. (S216) No drilling process is performed.

  Then, according to the user's specification, the control unit 700 selects an image forming mode to be executed (S217), and a toner image is formed in any one of four colors, five colors, and a transparent mode (S218, S219, S220). .

  The recording material S on which the toner image is fixed is discharged to the discharge tray 4 through the conveyance path 8 (S221).

  If multiple fixing is selected (S210, Yes), the protruding roller 61 is separated from the rubber roller 62 (S211). At this time, in the image forming portions Pa, Pb, Pc, and Pd, the four-color mode is executed, and a YMCK toner image is formed on the intermediate transfer belt 30. Then, the toner image on the intermediate transfer belt 30 is secondarily transferred to the recording material S fed to the secondary transfer portion T2 without being punched, and subsequently fixed by the fixing device 50 (S212). The recording material S on which the YMCK toner image is fixed is conveyed toward the secondary transfer portion T2 via the refeed path 5 (S213). At this time, the protruding roller 61 is brought into contact with the rubber roller 62 (S214), and the surface on which the YMCK toner image is formed is punched in the previously performed four-color mode. When the secondary transfer of the YMCK toner image formed in the four-color mode is completed, the transparent mode is executed, and the transparent toner image is secondarily transferred and fixed on the surface of the recording material S that has been punched (S215). The recording material S on which the transparent toner image is fixed is discharged to the paper discharge tray 4 (S211).

  Note that the method of selecting multiple fixing in S203 and S209 is performed in the same manner as S107 of FIG. 6 shown in the flowchart of the first embodiment.

  In this embodiment, as described above, the smoothing adjustment roller pair 60 performs the hole punching process, and the toner image is formed and fixed on the recording material S. As a result, the glossiness of the transparent toner on the color toner image of the preprint paper is It was 20.1. As a result, the glossiness increased by about 15.6 as compared with the case where no drilling process was performed.

  As described above, with the above-described configuration, a high gloss image can be obtained even when a toner image is formed on preprinted paper. Further, when it was not preprinted paper, a high-quality output product could be obtained without making a hole.

  In the first and second embodiments described above, the punching operation is performed when the recording material S is preprinted paper, and the punching operation is not performed when the recording material S is not preprinted paper. However, in Embodiments 1 and 2, when the recording material S is preprinted paper and the fixed image is a character image, the punching operation may not be performed.

Schematic of the image forming apparatus of Embodiment 1 Schematic of the smoothness adjustment roller pair of Embodiments 1 and 2 Schematic of the protruding roller 61 of the first and second embodiments FIG. 4 is a diagram for explaining a fixing process according to the first and second embodiments. Schematic of the operation unit of the first and second embodiments Flowchart of the operation of the smoothness adjusting roller pair 60 in the first embodiment. 1 is a block diagram of a circuit that executes control according to the first embodiment. Schematic diagram of an image forming apparatus according to a second embodiment Flowchart of the operation of the smoothness adjusting roller pair 60 in the second embodiment. 1 is a block diagram of a circuit that executes control according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 3 Registration roller 30 Intermediate transfer belt 23 Primary transfer roller 40 Secondary transfer roller 50 Fixing device 60 Smoothness adjustment roller pair 400 Operation part 500 Control part

Claims (3)

A transparent toner image forming means for forming an unfixed transparent toner image on a recording material on which a colored toner image is fixed in advance so as to overlap the colored toner image;
In an image forming apparatus having fixing means for fixing an unfixed transparent toner image formed on a recording material to a recording material by heating at a nip portion,
Smoothness adjusting means for reducing the smoothness of the color toner image fixed in advance on the recording material,
A control unit that causes the smoothness adjusting unit to act on the color toner image fixed in advance on the recording material, and then causes the transparent toner image forming unit to overlap the color toner image to form a transparent toner image; An image forming apparatus comprising:   2. The smoothing adjustment unit according to claim 1, wherein when there is no colored toner image fixed in advance on a recording material on which a transparent toner image is formed by the transparent toner image forming unit, the control unit does not operate the smoothness adjusting unit. Image forming apparatus. The smoothness adjusting means has a pressure contact member that presses the toner image and reduces the smoothness of the toner image,
The pressure on the toner image of the pressure contact member is 0.4 × 10 ³ Kgf / m ² or more and 3.2 × 0 ⁴ Kgf / m ² or less, and a plurality of protrusions are provided on the surface of the pressure contact member, 3. The image forming apparatus according to claim 1, wherein a height of the protrusions is 10 μm or more and less than 70 μm, and a distance between the protrusions is 200 μm or more and 1.0 mm or less.

Images