WO2021141815A1

WO2021141815A1 - Photo-finishing apparatus

Info

Publication number: WO2021141815A1
Application number: PCT/US2020/067504
Authority: WO
Inventors: Heungsup Park; Juntae Kim; Haeseog JO; Choongkyu PARK; YoungHoon HAN; Seungjun Lee
Original assignee: Hewlett-Packard Development Company, L.P.
Priority date: 2020-01-07
Filing date: 2020-12-30
Publication date: 2021-07-15
Also published as: KR20210088895A

Abstract

The image forming apparatus includes an image forming part to form a color toner image on a print medium and to form a clear toner image on the print medium; and a photo finishing part to receive the print medium from the image forming part at a downstream side of the image forming part and to form an oil coating layer on an image plane of the print medium.

Description

PHOTO-FINISHING APPARATUS

BACKGROUND

[0001] An electrophotographic image forming apparatus forms an electrostatic latent image by scanning light onto a photoconductor charged at a uniform electric potential and supplying a toner to the electrostatic latent image to form a toner image on the photoconductor. The toner image is transferred onto a recording medium such as a print medium directly or via an intermediate transfer belt. The toner image transferred onto the print medium is attached to the print medium by electrostatic force. A fuser applies heat and pressure to the toner image to fix the toner image as a permanent image on the print medium.

[0002] When high gloss paper is used as the print medium, a print image such as a photograph may be printed. When inexpensive plain paper is used as the print medium, a photograph would be difficult to print as the print image since inexpensive plain paper has low glossiness.

BRIEF DESCRIPTION OF THE DRAWINGS

[0003] FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus.

[0004] FIG. 2 is a cross-sectional view of an example of a substrate.

[0005] FIG. 3 is a schematic configuration diagram of an example of an image forming apparatus capable of selective photo finishing processing.

[0006] FIG. 4 is a schematic configuration diagram of an example of an image forming apparatus in which functions of a fuser and a photo finishing unit are l integrated.

[0007] FIG. 5 is a schematic configuration diagram of an example of an image forming apparatus having a structure of forming a clear toner image on a print medium on which a color image is formed and capable of photo finishing processing.

[0008] FIG. 6 is a schematic configuration diagram of an example of an image forming apparatus capable of selective photo finishing processing.

[0009] FIG. 7 is a schematic configuration diagram of an example of an image forming apparatus including a detachable prost-processing unit and capable of photo finishing processing.

DETAILED DESCRIPTION

[0010] FIG. 1 is a schematic configuration diagram of an example of an image forming apparatus. FIG. 2 is a cross-sectional view of an example of a substrate 90. Referring to FIGS. 1 and 2, the image forming apparatus includes, inside of a main body 1000, an image forming part (or image former) 1 for forming a toner image on a recording medium such as print medium P, a fuser 3 for fixing the toner image onto the print medium P, and a photo finishing part (or photo finisher) 2 located at a downstream side of the fuser 3 and forming an oil coating layer CL on an image plane of the print medium P. An example of a recording medium is print medium P. The term print medium is used throughout, but the recording medium is not limited to print medium and may be other types of recording medium as well.

[0011 ] The image forming part 1 includes a color image forming part 1 a to form a color toner image on the print medium P, and a clear image forming part 1b to form a clear toner image on the print medium P. The post-processing apparatus 1001 includes a substrate 90 having the oil coating layer CL formed on one surface thereof, and a finishing part 2 to form a coating nip CN through which the substrate 90 and the print medium P pass while overlapping each other and thermally transferring the oil coating layer CL on the image plane of the print medium P. [0012] The color image forming part 1a of the present example forms the color toner image on the print medium P by using an electrophotographic method. As an example, the color image forming part 1a may include an exposure device 10, a developing device 20, and a transfer device an example of which is disclosed herein below.

[0013] For color printing, the developing device 20 may include, for example, four developing devices 20C, 20M, 20Y, and 20K to develop an image of cyan C, magenta M, yellow Y, and black K colors. The four developing devices 20C, 20M, 20Y, and 20K may include developers, for example, toners of cyan C, magenta M, yellow Y, and black K colors, respectively. The toners of cyan C, magenta M, yellow Y, and black K colors may be included in four toner supply containers 70C, 70M, 70Y, and 70K, respectively, and may be supplied to the four developing devices 20C, 20M, 20Y, and 20Kfrom the four toner supply containers 70C, 70M, 70Y, and 70K, respectively. The image forming apparatus may further include a developing device to include developing toners of various colors such as light magenta, white, etc. in addition to the above-described colors. A toner supply container 70 may be replaced when the toner included therein is consumed. The developing device 20 may be detachably attached to the image forming apparatus.

[0014] Hereinafter, the color image forming part 1a including the four developing devices 20C, 20M, 20Y, and 20K will be described. Unless otherwise specified, elements including C, M, Y, and K denote components for developing the image of cyan C, magenta M, yellow Y, and black K colors, respectively. [0015] The developing device 20 may include a photosensitive drum 21. The photosensitive drum 21 may be a member independent of the developing device 20. The photosensitive drum 21 , which is an example of a photoconductor to form an electrostatic latent image on a surface thereof, may include a conductive metal pipe and a photosensitive layer formed on a circumference thereof. A charging roller 22 is an example of a charger that charges the photosensitive drum 21 to have a uniform surface electric potential. A charging bias voltage is applied to the charging roller 22. Instead of the charging roller 22, a charging brush, a corona charger, or the like may be employed. The developing device 20 may further include a cleaning roller (not shown) to remove foreign substances from a surface of the charging roller 22. A cleaning blade 25 is an example of a cleaning member to remove toner and foreign substances remaining on the surface of the photosensitive drum 21 after a transfer process described later. A different type of cleaning member such as a brush to be rotated may be employed instead of the cleaning blade 25.

[0016] The developing device 20 supplies toner to the electrostatic latent image formed on the photosensitive drum 21 to develop the electrostatic latent image into a visible toner image. Developing methods may include a one-component developing method using toner, and a two-component developing method using toner and carrier. The developing device 20 of the present example employs the one-component developing method. A developing roller 23 supplies the toner to the photosensitive drum 21. A developing bias voltage to supply the toner to the photosensitive drum 21 may be applied to the developing roller 23. In the present example, a contact developing method in which the developing roller 23 and the photosensitive drum 21 contact each other to form a developing nip is used. A supply roller 24 supplies the toner in the developing device 20 to a surface of the developing roller 23. To this end, a supply bias voltage may be applied to the supply roller 24. The developing device 20 may further include a regulating member (not shown) to regulate an amount of toner which is attached to the surface of the developing roller 23 and supplied to the developing nip where the photosensitive drum 21 and the developing roller 23 are in contact with each other. The regulating member may be, for example, a doctor blade that elastically contacts the surface of the developing roller 23.

[0017] The exposure device 10 irradiates light modulated in correspondence with image information onto the photosensitive drum 21 to form the electrostatic latent image on the photosensitive drum 21. As the exposure device 10, a laser scanning unit (LSU) that uses a laser diode as a light source, and a light emitting diode (LED) exposure device that uses an LED as a light source, etc. may be employed.

[0018] The transfer device may include an intermediate transfer belt 30, intermediate transfer rollers 41 , 42, 43 and 44, and a transfer roller 50. The toner image developed on the photosensitive drum 21 of each of the developing devices 20C, 20M, 20Y, and 20K is temporarily transferred to the intermediate transfer belt 30. The intermediate transfer belt 30 is supported by the support rollers 31 and 32 to circulate and travel. The four intermediate transfer rollers 41 , 42, 43 and 44 are disposed at positions opposing the photosensitive drum 21 of each of the developing devices 20C, 20M, 20Y, and 20K with the intermediate transfer belt 30 therebetween. An intermediate transfer bias voltage for intermediate transferring the toner image developed on the photosensitive drum 21 is applied to the four intermediate transfer rollers 41 , 42, 43 and 44. Instead of the intermediate transfer rollers 41 , 42, 43 and 44, a corona transfer unit or a pin scorotron transfer unit may be employed. The transfer roller 50 is positioned to oppose the intermediate transfer belt 30. A transfer bias voltage for transferring the toner image intermediate-transferred to the intermediate transfer belt 30 onto the print medium P is applied to the transfer roller 50.

[0019] When a print command is received from, for example, a host which is not shown or the like, a control unit which is not shown charges the surface of the photosensitive drum 21 to a uniform electric potential using the charging roller 22. The exposure device 10 scans the photosensitive drum 21 of each of the developing devices 20C, 20M, 20Y, and 20K with four light beams modulated corresponding to the image information of each color to form the electrostatic latent image on the photosensitive drum 21. The developing roller 23 of each of the developing devices 20C, 20M, 20Y and 20K supplies the toners of C, M, Y and K colors respectively to the corresponding photosensitive drums 21 to develop the electrostatic latent image into a visible color toner image. The visible color toner images are overlapped and transferred onto the intermediate transfer belt 30. The print medium P loaded on a feed tray 80 is transported to the transfer nip formed by the transfer roller 50 and the intermediate transfer belt 30. The color toner images, which are intermediately transferred onto the intermediate transfer belt 30, are transferred to the print medium P by the transfer bias voltage applied to the transfer roller 50.

[0020] The image forming apparatus of the present example forms a clear toner image on the print medium P by using the clear image forming part 1b before photo finishing. The clear image forming part 1b may form the clear toner image on the entire image plane of the print medium P. The clear image forming part 1 b may form the clear toner image on at least a part of a non-image portion of the image surface of the print medium P on which the color toner image is not formed. For example, the clear image forming part 1b may form a clear toner image on an entire non-image portion of the image plane of the print medium P, or the entire non-image portion and a low image density portion of a portion (an image portion) on which the color toner image is formed. The clear image forming part 1b may form a clear toner image having a specific pattern on a specific region of the image plane of the print medium P.

[0021 ] When the clear toner image is formed on the entirety of the image plane of the print medium P, a non-exposure type electrophotographic method may be employed for the clear image forming part 1 b.

[0022] Referring to FIG. 1 , the clear image forming part 1b may include a containing unit 415 in which the clear toner CT is included, a charge receiving member 411 , a charge supplying member 412 to supply a charge of an opposite polarity to a charge polarity of the clear toner CT to the charge receiving member 411 , a developing member 413 to which a developing bias voltage to develop the clear toner CT onto the charge receiving member 411 is applied and to attach the clear toner CT included in the containing unit 415 to the charge receiving member 411 , and a transfer member 414 to which a transfer bias voltage of the opposite polarity to the charge polarity of the clear toner CT is applied, to oppose the charge receiving member 411 with the intermediate transfer belt 30 therebetween, and to transfer the clear toner CT attached to the charge containing member 411 to the intermediate transfer belt 30. The clear toner CT may be supplied from a clear toner container 440 to the containing unit 415. [0023] When the clear toner image is formed on at least a part of the non-image portion of the image plane of the print medium P, an exposure-type electrophotographic method may be employed for the clear image forming part

1 b.

[0024] A structure of the clear image forming part 1 b may refer to a structure of the color image forming part 1a that forms a toner image on the print medium P by using the electrophotographic method. For example, in FIG. 1 , the charge receiving member 411, the charge supplying member 412, the developing member 413, and the transfer member 414 may be, respectively, a photosensitive drum, a charging roller, a developing roller, and a transfer roller. In addition in the example of FIG. 1 , as shown by a dashed line, an exposure device 420 that forms an electrostatic latent image may further be employed. A charging bias voltage may be applied to a charging roller to charge a surface of a photosensitive drum to a uniform electric potential. An electrostatic latent image corresponding to a clear toner image may be formed by irradiating light onto the charged surface of the photosensitive drum by using the exposure device 420. A developing bias voltage may be applied to a developing roller opposing the photosensitive drum to supply the clear toner CT to the electrostatic latent image to form a clear toner image on the surface of the photosensitive drum. A transfer bias voltage may be applied to a transfer roller, which is opposed to the photosensitive drum and which forms a transfer nip, to transfer the clear toner image to the intermediate transfer belt 30.

[0025] The color toner image and the clear toner image are formed on the intermediate transfer belt 30 according to the above-described process. The print medium P loaded on a feed tray 80 is transported to the transfer nip in which the transfer roller 50 and the intermediate transfer belt 30 face each other along a print path 81. The color toner image and the clear toner image on the intermediate transfer belt 30 are transferred to the print medium P by the transfer bias voltage applied to the transfer roller 50.

[0026] When the color toner image and the clear toner image are transferred to the print medium P, the clear toner image may be an outermost layer or an innermost layer. To this end, in the intermediate transfer belt 30, the clear toner image is the innermost layer or the outermost layer. Therefore, the clear image forming part 1b may apply the clear toner to the intermediate transfer belt 30 on an upstream side or a downstream side of the developing device 20 based on a traveling direction of the intermediate transfer belt 30.

[0027] In the present example, the clear image forming part 1b is disposed at the downstream side of the color image forming part 1a based on the traveling direction of the intermediate transfer belt 30. For example, as shown in FIG. 1 , the clear image forming part 1b may be disposed at a downstream side relative to the developing device 20K disposed at the most downstream side based on the traveling direction of the intermediate transfer belt 30 among the four developing devices 20C, 20M, 20Y, and 20K. In this case, the clear toner on the print medium P becomes the innermost layer.

[0028] Conversely, although not shown in FIG. 1 , the clear image forming part 1 b may be disposed at an upstream side relative to the developing device 20C disposed at the most upstream side based in the traveling direction of the intermediate transfer belt 30 among the four developing devices 20C, 20M, 20Y, and 20K. In this case, the clear toner on the print medium P becomes the outermost layer.

[0029] The fuser 3 fixes the color toner image and the clear toner image on the print medium P by applying heat and pressure to the print medium P onto which the color toner image and the clear toner image are transferred. The fuser 3 may be implemented in various forms. For example, the fuser 3 may include a heating member and a pressing member. The heating member and the pressing member are elastically pressed against each other to form a fixing nip. The heating member may be implemented in the form of, for example, a heat roller, a fixing belt, or the like. The heating member is heated by a heat source. As the heat source, for example, a halogen lamp may be employed. The heating member is in contact with the image plane of the print medium P. The image plane is a surface onto which the toner image is transferred. When the print medium P, onto which the toner image is transferred, passes through the fixing nip, the toner image is fixed to the print medium P by heat and pressure.

[0030] An example of the substrate 90 and the photo finishing part 2 forming the post-processing apparatus 1001 will be described below. The photo finishing part 2 is disposed at a downstream of the image forming part 1 and forms the oil coating layer CL on the image plane of the print medium P which has passed through the image forming part 1. The image forming apparatus of the present example includes a fuser 3 positioned between the image forming part 1 and the photo finishing part 2 to fix the color toner image and the clear toner image to the print medium P. Therefore, the photo finishing part 2 is disposed at a downstream of the fuser 3 and forms the oil coating layer CL on the image plane of the print medium P which has passed through the fuser 3. The photo finishing part 2 thermally transfers the oil coating layer CL to the image plane of the print medium P from the substrate 90 in which the oil coating layer CL is supported on one surface as shown in FIG. 2.

[0031] The substrate 90 may include a material that is not deformed at the operating temperature of the photo finishing part 2. For example, as the substrate 90, a polyethylene film such as polyethylene terephthalate, a polyester film, etc. may be employed. The oil coating layer CL may be a transparent polymer oil coating layer CL. The oil coating layer CL may be supported on the substrate 90 in a solid state. The polymer oil coating layer CL is separated from the substrate 90 by heat and is transferred to the image plane of the print medium P. As the oil coating layer CL, oil which is not deformed at the operating temperature of the photo finishing part 2, for example, silicone oil, fluorine oil, hydrocarbon oil, etc., may be employed. In the present example, silicone oil is employed as the oil coating layer CL. The surface tension of the oil coating layer CL may be 15 to 50 dynes/cm. It is difficult to form polymer oil with a surface tension of less than 15 dynes/cm. When the surface tension is greater than 50 dynes/cm, it may be difficult to separate the oil coating layer CL from the substrate 90, and the toner on the print medium P may be reversely transferred to the oil coating layer CL on the substrate 90. The viscosity of the oil coating layer CL may be 0.1 to 1000 centipoises at an operating temperature range of the photo finishing part 2, for example, 80 °C to 120 °C. When the viscosity of the oil coating layer CL is lower than 0.1 centipoises, because it is difficult to solidify the oil coating layer CL, the oil coating layer CL may not be supported in a solid state on one surface of the substrate 90. When the viscosity of the oil coating layer CL is greater than 1000 centipoises, it is difficult to liquefy the oil coating layer CL at the operating temperature range of the photo finishing part 2, for example, at 80 °C to 120 °C. Therefore, it is difficult to transfer the oil coating layer CL from the substrate 90 to the print medium P.

[0032] The photo finishing part 2 may be implemented in various forms. Referring to FIG. 1, the photo finishing part 2 may include a pair of coating members which are engaged with each other to form the coating nip CN through which the substrate 90 and the print medium P pass while overlapping each other and heats the substrate 90 to thermal transfer the oil coating layer CL to the print medium P. In an example, the pair of coating members may include a heating roller 210 and a pressing roller 220.

[0033] The heating roller 210 may include a metal core such as hollow aluminum (Al) or stainless steel. To improve the releasability from the substrate 90, a release layer may be formed on the outer circumference of the metal core. To form the stable coating nip CN, a heat resistant elastic layer may be provided between the metal core and the release layer. The heating roller 210 faces a surface of the substrate 90 opposite to the oil coating layer CL and applies heat to the substrate 90. The heating roller 210 is heated by a heat source 230. As the heat source 230, a halogen lamp, a heating resistance coil, an induction heater, a ceramic heater, etc. may be employed. In the present example, a halogen lamp is employed as the heat source 230. The halogen lamp may be installed inside the metal core at a position substantially equal to a rotation axis of the heating roller 210. The image plane of the print medium P faces the oil coating layer CL.

[0034] The pressing roller 220 is pressed against the heating roller 210 to form the coating nip CN through which the print medium P and the substrate 90 pass. The pressing roller 220 may be a structure in which a heat resistant elastic layer and the release layer using a heat resistant resin coating or a heat resistant rubber coating are formed on the outer surface of the metal core. The pressing roller 220 faces a surface of the print medium P opposite to the image surface and presses the print medium P to be closely contacted to the oil coating layer CL. Although not shown in the drawings, the pressing roller 220 may also be heated, and in this case, a heat source (not shown) heating the pressing roller 220 may be further provided.

[0035] The temperature of the heating roller 210 may be equal to or higher than the liquefaction temperature of the oil coating layer CL. The temperature of the heating roller 210 may be, for example, about 80 °C to about 120 °C. The heating roller 210 may be heated to an appropriate temperature depending on the photo finishing processing speed and the length of the coating nip CN.

[0036] The photo finishing part 2 may include a supply member 240 which is disposed at the upstream side of the coating nip CN based on the traveling direction of the print medium P and supplies the substrate 90 to the coating nip CN and a recovery member 250 which is disposed at the downstream side of the coating nip CN based on the traveling direction of the print medium P and recovers the substrate 90 passing through the coating nip CN.

[0037] The supply member 240 and the recovery member 250 may be, for example, in the form of a reel that rotates. The substrate 90, on which the oil coating layer CL is supported, is provided to have one end connected to the supply member 240 and wound around the supply member 240. The other end of the substrate 90 extends from the supply member 240 and passes through the coating nip CN to be connected to the recovery member 250. The supply member 240 rotates in the direction in which the substrate 90 is unwound, and the recovery member 250 rotates in the direction in which the substrate 90 is wound. A supply guide member 261 guides the substrate 90 unwound from the supply member 240 to the coating nip CN. A recovery guide member 262 guides the substrate 90 that has passed through the coating nip CN to the recovery member 250. The supply guide member 261 and the recovery guide member 262 may be implemented in various forms including, for example, a cylindrical post, a rotating roller, a plate having a curved surface for smoothly guiding the substrate 90, etc. The supply guide member 261 and the recovery guide member 262 are respectively disposed at upstream and downstream sides of the coating nip CN such that the substrate 90 remains flat therebetween. As a result, the print medium P may stably overlap the substrate 90. A discharge roller 271 discharges the print medium P passing through the coating nip CN to outside of the photo finishing part 2.

[0038] With the above-described configuration, a photo finishing processing procedure will be described.

[0039] The print medium P, on which the color toner image and the clear toner image are formed on the image plane by the image forming part 1 , is guided to the fuser 3. The fuser 3 fixes the color toner image and the clear toner image to the print medium P by heat and pressure. The print medium P, which has passed through the fuser 3, is guided to the photo finishing part 2. The print medium P overlaps the substrate 90 that remains flat by the supply guide member 261 and the recovery guide member 262 and enters the coating nip CN. In the coating nip CN, the oil coating layer CL on the substrate 90 is melted by heat and pressure, separated from the substrate 90, transferred to the image plane of the print medium P, and coated. The substrate 90, from which the oil coating layer CL is separated, is wound around the recovery member 250. The discharge roller 271 discharges the print medium P having the image plane on which the oil coating layer CL is formed. This completes photo finishing processing.

[0040] When a high gloss paper, for example, photo paper, is used as the print medium P, there is a small difference in glossiness between a part on which a printed image is formed and a part on which the printed image is not formed, and, thus, a printed image such as a photograph may be printed. However, photo paper is more expensive than plain paper, which has low glossiness.

[0041 ] After printing an image using plain paper with low glossiness as the print medium P, the glossiness of the printed image may be improved by performing photo finishing processing on the printed image, and thus, a printed image such as a photograph may be printed. The oil coating layer CL is formed in a part of the image plane of the print medium P where the toner image is present. When a color image is formed on the print medium P, the oil coating layer CL is formed only on an image portion having the color image and is not formed on a non-image portion having no color image. Therefore, the glossiness of the image portion and the non-image portion may be different, resulting in uneven glossiness of the image plane.

[0042] The image forming apparatus of the present example forms a clear image using a clear toner on the entire non-image portion or at least a part of the non-image portion and then performs photo finishing processing on the clear image. As a result, the oil coating layer CL may be formed on the entirety of the image portion and the non-image portion, and thus, the glossiness of the image plane may be uniform. [0043] In addition, unevenness in glossiness may occur depending on the image density of the color image. For example, a surface of the print medium P is not exposed in a high image density part of the color image because a large amount of color toner is transferred to the high image density part. The surface of the print medium P may be partially exposed in a low image density part of the color image because a small amount of color toner is transferred to the low image density part. When photo finishing processing is performed on such a printed image, the glossiness of the low image density part is lower than that of the high image density part, resulting in glossiness non-uniformity of the printed image even though photo finishing processing is performed. According to the image forming apparatus of the present example, a clear image may be formed not only on the non-image portion but also on a portion of the color image where the image density is low. Accordingly, the glossiness of the image plane may be more uniform.

[0044] According to such a configuration, because the glossiness of the image portion and the non-image portion is generally improved, a printout with a uniform glossiness such as a photograph may be obtained using plain paper at low cost compared to using a photo paper. In addition, compared to a method of improving the glossiness through reheating and cooling processes after forming the color image and the clear image, because cooling time is not required, the photo finishing processing speed may be improved.

[0045] In addition, the clear image forming part 1 b and the photo finishing part 2 may be used to form a specific pattern on the image plane due to the difference in glossiness. For example, a clear image of a specific pattern is formed on the image plane by using a clear toner, and photo finishing processing is performed on the clear image. Then, the glossiness of the clear image may be selectively improved such that a gloss pattern may be formed on the image plane.

[0046] FIG. 3 is a schematic configuration diagram of an example of an image forming apparatus. In the example of the image forming apparatus of FIG. 3, photo finishing processing may be selectively performed. The print medium P having an image plane on which an image is printed by the image forming part 1 and the fuser 3 is guided to a discharge path 82 without photo finishing processing and is discharged to outside of a main body 1000 by the discharge roller 83 or transferred to the photo finishing part 2 for photo finishing processing such as gloss processing. Referring to FIG. 3, the image forming apparatus may further include a path selecting member 1002 located at an exit of the fuser 3 and to selectively guide the print medium P to the discharge path 82 and the photo finishing part 2. The path selecting member 1002 may be switched to a first position (a position shown by a solid line) that directly discharges the print medium P that passed through the fuser 3 from the main body 1000 through the discharge path 82 without performing gloss processing on the print medium P, and a second position (a position shown by a dashed line) that guides the print medium P that passed through the fuser 3 to the photo finishing part 2 such that the print medium P may pass through the coating nip CN by being driven by, for example, a solenoid. According to the configuration described above, selective gloss processing is possible and, thus, photo finishing processing is selectively performed.

[0047] In other words, when paper with a high glossiness is used as the print medium P, the path selecting member 1002 may be disposed at the first position to directly discharge the print medium P that passed through the image forming part 1 and the fuser 3 from the main body 1000 without performing gloss processing on the print medium P. In this case, only the color image forming part 1a may operate, and the clear image forming part 1b may not operate.

[0048] When plain paper with low glossiness is used as the print medium P, the path selecting member 1002 may be disposed at the first position or the second position as necessary to selectively guide the print medium P that passed through the image forming part 1 to the discharge path 82 and the photo finishing part 2.

[0049] For example, when photo finishing processing is not performed, the path selecting member 1002 may be disposed at the first position to directly discharge the print medium P that passed through the image forming part 1 and the fuser 3 from the main body 1000 without performing gloss processing on the print medium P. In this case, only the color image forming part 1a may operate, and the clear image forming part 1b may not operate. Both the color image forming part 1a and the clear image forming part 1b may operate, thereby improving the glossiness of the image printed on the plain paper.

[0050] For example, when photo finishing processing is performed, the path selecting member 1002 may be disposed at the second position to guide the print medium P that passed through the image forming part 1 and the fuser 3 and the color image and the clear image that are printed on the image plane to the photo finishing part 2. The guide roller 270 transports the print medium P discharged from the fuser 3 to the coating nip CN. The print medium P overlaps the substrate 90 that is supplied from the supply member 240 and remains flat by the supply guide member 261 and the recovery guide member 262 and enters the coating nip CN. In the coating nip CN, the oil coating layer CL is transferred to the image plane of the print medium P by heat and pressure. The print medium P having the image plane on which the oil coating layer CL is formed is discharged from the photo finishing part 2 by the discharge roller 271. Accordingly, the glossiness of the image printed on the plain paper may be further improved, thereby obtaining a printed image such as a photograph.

[0051] FIG. 4 is a schematic configuration diagram of an example of an image forming apparatus. In the image forming apparatus of the present example, a photo finishing part 2a also functions as the fuser 3 and the photo finishing part 2 shown in FIGS. 1 and 3. Among the components illustrated in FIG. 4, the same components as those illustrated in FIGS. 1 and 3 are denoted by the same reference numerals, and redundant descriptions thereof will be omitted.

[0052] Referring to FIG. 4, an image forming part T and the photo finishing part 2a are shown. The image forming part T of the present example forms a color toner image and a clear toner image on the print medium P by using an electrophotographic method. The structure of the image forming part T is the same as that of the image forming part 1 shown in FIGS. 1 and 3, except that the image forming part T has no fuser 3. The substrate 90 and the photo finishing part 2a form the post-processing apparatus 1001. The photo finishing part 2a forms the coating nip CN through which the substrate 90 in which the oil coating layer CL is supported on one surface and the print medium P on which the color toner image and the clear toner image are formed pass while overlapping each other and fixes the color toner image, the clear toner image, and the oil coating layer CL to the print medium P. The structure of the photo finishing part 2a is the same as that of the photo finishing part 2 shown in FIGS. 1 and 3. The heating roller 210 is heated to a temperature at which fixing is available.

[0053] When a print command is received from, for example, a host which is not shown or the like, a controller such as a control unit which is not shown drives the color image forming part 1a and the clear image forming part 1b to form the color toner image and the clear toner image on the intermediate transfer belt 30. The print medium P loaded on a feed tray 80 is transported to the transfer nip in which the transfer roller 50 and the intermediate transfer belt 30 face each other along a print path 81. The color toner image and the clear toner image on the intermediate transfer belt 30 are transferred to the print medium P by the transfer bias voltage applied to the transfer roller 50.

[0054] The print medium P having the color toner image and the clear toner image is transported to the photo finishing part 2a. The print medium P overlaps the substrate 90 supplied from the supply member 240 and remains flat by the supply guide member 261 and the recovery guide member 262 and enters the coating nip CN. The image plane of the print medium P faces the oil coating layer CL. In the coating nip CN, the color toner image and the clear toner image are melted and fixed to the print medium P by heat and pressure and simultaneously the oil coating layer CL is separated from the substrate 90 and transferred to an image plane of the print medium P and coated. The substrate 90 from which the oil coating layer CL is separated is wound around the recovery member 250. The print medium P having the image plane on which the oil coating layer CL is formed is discharged from the photo finishing part 2a by the discharge roller 271. This simultaneously completes fixing and photo finishing processing.

[0055] According to the configuration described above, compared to the image forming apparatus shown in FIGS. 1 and 3, the fuser 3 may be omitted, and thus, an image forming apparatus capable of photo finishing at low cost may be implemented.

[0056] FIG. 5 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of the present example includes an image forming part (or image former) 100 and a photo finishing part (or photo finisher) 200. The image forming part 100 includes a color image forming part 101 forming a color image and a clear image forming part 102 forming a clear toner image. A post-processing apparatus 100T includes the substrate 90, the photo finishing part 200, and the clear image forming part 102. Feed tray 61 corresponds to feed tray 80 in FIGS. 1 and 3 [0057] The color image forming part 101 has a structure in which the color image forming part 1a forming the color toner image on the print medium P shown in FIGS. 1 and 3 and the fuser 3 fixing the color toner image to the print medium P to form the color image are merged. The clear image forming part 102 forms the clear toner image on the print medium P on which the color image is formed and has a structure similar to that of the clear image forming part 1b shown in FIGS. 1 and 3. However, the clear image forming part 102 is different than the clear image forming part 1b shown in FIGS. 1 and 3 in that the transfer member 414 faces the charge receiving member 411 with the print medium P passing through the fuser 3 therebetween.

[0058] The photo finishing part 200 is different from the photo finishing part 2 shown in FIGS. 1 and 3 in that the photo finishing part 200 heats and presses the print medium P to fix the clear toner image to the image plane of the print medium P, and simultaneously transfers and coats the oil coating layer CL from the substrate 90 to the image plane of the print medium P.

[0059] According to such a configuration, an image forming apparatus capable of photo finishing processing may be implemented while minimizing a change in the layout of an image forming apparatus of the related art that does not include the clear image forming part 102. That is, the image forming apparatus to which the post-processing apparatus 100T for photo finishing processing is applied may be implemented with little change in the layout of the main body 1000 including the color image forming part 101.

[0060] FIG. 6 is a schematic configuration diagram of an example of an image forming apparatus. The image forming apparatus of the present example is different than the image forming apparatus of an example shown in FIG. 5 in that photo finishing process may be selectively performed. Referring to FIG. 6, the path selecting member 1002 selectively guiding the print medium P to the discharge path 82 and the post-processing apparatus 100T is provided. The path selecting member 1002 may be switched to a first position (a position shown by a solid line) that directly discharges the print medium P that passed through the color image forming part 101 from the main body 1000 through the discharge path 82 without performing gloss processing on the print medium P, and a second position (a position shown by a dashed line) that guides the print medium P that passed through the color image forming part 101 to the clear image forming part 102 and the photo finishing part 200 such that the print medium P may pass through the coating nip CN, by driving means such as a solenoid. According to the configuration described above, selective gloss processing is possible.

[0061] FIG. 7 is a schematic configuration diagram of an example of an image forming apparatus. Referring to FIG. 7, the main body 1000 including the color image forming part 101 and the post-processing apparatus 1001 ' including the substrate 90, the clear image forming part 102, and the photo finishing part 200 are shown. The post-processing apparatus 1001 ' is detachable from the main body 1000. The color image forming part 101 , the clear image forming part 102, and the photo finishing part 200 are the same as those described with reference to FIG. 5. The path selecting member 1002 may be switched to a first position (a position shown by a solid line) that directly discharges the print medium P that passed through the color image forming part 101 from the main body 1000 through the discharge path 82 without performing gloss processing on the print medium P, and a second position (a position shown by a dashed line) that guides the print medium P that passed through the color image forming part 101 to the post-processing apparatus 100T such that the print medium P may pass through the clear image forming part 102 and the photo finishing part 200, by driving means such as a solenoid.

[0062] When there is no post-processing apparatus 1001 ', the print medium P that passed through the color image forming part 101 is guided to the discharge path 82 by the path selection member 1002 disposed at the first position and discharged from the main body 1000 by the discharge roller 62 without performing glossiness processing.

[0063] When the post-processing apparatus 1001 ' is mounted on the main body 1000, selective photo finishing processing is possible. When photo finishing processing is performed, the print medium P that passed through the color image forming part 101 is guided to the post-processing apparatus 100T by the path selection member 1002 disposed at the second position to form a clear toner image and undergoes photo finishing processing and is discharged from the post-processing apparatus 100Γ by the discharge roller 271.

[0064] It should be understood that examples described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each example should typically be considered as available for other similar features or aspects in other examples. While one or more examples have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope as defined by the following claims.

Claims

WHAT IS CLAIMED IS:

1. An image forming apparatus comprising: an image forming part to form a color toner image on a print medium and a clear toner image on the print medium; and a photo finishing part to receive the print medium from the image forming part at a downstream side of the image forming part and to form an oil coating layer on an image plane of the print medium.

2. The image forming apparatus of claim 1 , further comprising: a substrate having the oil coating layer formed on one surface thereof; a pair of coating rollers, engaged with each other to form a coating nip through which the substrate and the print medium pass while overlapping each other, to heat the substrate to thermally transfer the oil coating layer to the print medium; a supply member, at an upstream side of the coating nip based on a traveling direction of the print medium, to supply the substrate to the coating nip; and a recovery member, at a downstream side of the coating nip based on the traveling direction of the print medium, to recover the substrate having passed through the coating nip.

3. The image forming apparatus of claim 2, wherein a surface tension of oil forming the oil coating layer is 15 to 50 dynes/cm.

4. The image forming apparatus of claim 2, wherein a viscosity of oil forming the oil coating layer is 0.1 to 1000 centipoises at 80 °C to 120 °C.

5. The image forming apparatus of claim 4, wherein the oil forming the oil coating layer is any one of silicone oil, fluorine oil, hydrocarbon oil.

6. The image forming apparatus of claim 1, wherein the image forming part further comprising a clear image forming part is to form the clear toner image on at least a part of the image plane of the print medium.

7. The image forming apparatus of claim 1 , wherein the clear toner image is formed on a non-image portion of the print medium on which the color toner image is not formed.

8. The image forming apparatus of claim 1 , wherein the image forming part comprises: an intermediate transfer belt in which the color toner image and the clear toner image are temporarily received; and a transfer roller facing the intermediate transfer belt with the print medium interposed therebetween to form a transfer nip and to transfer the color toner image and the clear toner image to the print medium passing through the transfer nip.

9. The image forming apparatus of claim 8, wherein the image forming part further comprising a color image forming part to form the color toner image and a clear image forming part to form the clear toner image, and wherein the clear image forming part is at a downstream side of the color image forming part based on a traveling direction of the intermediate transfer belt.

10. The image forming apparatus of claim 1, further comprising a fuser between the image forming part and the photo finishing part to fix the color toner image and the clear toner image to the print medium.

11. The image forming apparatus of claim 10, further comprising a path selection member at an exit of the fuser to selectively guide the print medium to the photo finishing part.

12. A post-processing apparatus comprising: a substrate having an oil coating layer formed on one surface thereof; and a photo finishing part to form a coating nip through which the substrate and a print medium pass while overlapping each other and to thermally transfer the oil coating layer to an image plane of the print medium.

13. The post-processing apparatus of claim 12, further comprising a clear image forming part to form a clear toner image on the image plane of the print medium.

14. The post-processing apparatus of claim 13, wherein the photo finishing part comprises: a supply member, at an upstream side of the coating nip based on a traveling direction of the print medium, to supply the substrate to the coating nip; a recovery member, at a downstream side of the coating nip based on the traveling direction of the print medium, to recover the substrate having passed through the coating nip; and a heating roller and a pressing roller engaged with each other to form the coating nip and to fix the color toner image, the clear toner image, and the oil coating layer to the print medium.

15. The post-processing apparatus of claim 12, wherein oil forming the oil coating layer is any one of silicone oil, fluorine oil, hydrocarbon oil.