JP2013213894A - Image forming apparatus and image forming system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adhesion of a plurality of sheets on which a transparent toner layer is formed.SOLUTION: An image forming apparatus includes: a transparent toner supply unit that supplies transparent toner; a transfer unit that transfers the transparent toner supplied from the transparent toner supply unit to a sheet; a fixing unit that fixes the transparent toner on the sheet conveyed from the transfer unit; a separation sheet supply unit that supplies a separation sheet for a sheet-like member, and a control unit. The control unit controls to alternately eject the sheets conveyed from the fixing unit and the separation sheets supplied from the separation sheet supply unit.

Description

  The present invention relates to an image forming apparatus for forming a transparent toner layer on an image formed by, for example, an electrophotographic method, using a colorless and transparent toner (referred to as a transparent toner or a clear toner) used for imparting gloss. And an image forming system.

  Print images such as photographic images and posters have recently been produced in inkjet and electrophotographic image forming apparatuses in addition to conventional silver halide photographic and gravure printing methods.

  In the electrophotographic system, for example, toner images are formed (developed) on a plurality of photosensitive drums, and the formed toner images are primarily transferred onto an intermediate transfer member and superimposed, and the toner images formed on the intermediate transfer member are formed. Secondary transfer onto transfer material (paper). Then, the toner image that has been secondarily transferred is fixed on the sheet using a fixing device. Such a procedure enables full-color image formation.

  In general, glossy images are often required for posters, photographic images, and the like. However, for example, when a photographic image is formed using toner, uneven gloss may occur on the image. As a technique for eliminating gloss unevenness on an image, a technique for forming an image using a toner having a configuration in which a colorant component is removed from a normal colored toner, also called a clear toner or a transparent toner, has been developed.

  For example, a technique has been disclosed in which a glossy image forming apparatus is used to provide a glossy image by forming a transparent toner layer on an image formed by an image forming apparatus (see, for example, Patent Document 1). ).

  With reference to FIG. 9, an outline of a gloss applying system using a conventional image forming apparatus and a gloss applying apparatus will be described.

  The image forming apparatus 201 is an example of a general image forming apparatus that forms an image on a sheet by an electrophotographic method. The image forming apparatus 201 includes, for example, four image forming units 5Y, 5M, 5C, and 5K in order to form toner images of four colors of yellow (Y), magenta (M), cyan (C), and black (Bk). (Image forming unit 5). Further, a transparent toner supply unit 5S for supplying transparent toner made of, for example, a transparent resin used for glossing is provided. Further, the image forming apparatus 201 includes an intermediate transfer belt 6, a secondary transfer unit 7, and a fixing unit 8.

  On the other hand, the gloss applying device 220 includes, for example, a pair of a heating roller 22 and a pressure roller 23 (heating and pressing device), a belt member 24, cooling fans 25 and 26, and a plurality of conveying rollers. The gloss applying device 220 re-melts the transparent toner layer on the paper on which the transparent toner has been transferred and assumed, and cools it on a smooth surface to give the paper gloss. The hypothetical wear refers to a state where the transparent toner is fixed on the paper before the gloss is given (before the glossy finishing process is performed).

The flow of gloss application using the conventional gloss application system having the above-described configuration will be described.
First, a user stacks and arranges sheets P0 on which images are formed on the manual feed portion 4 of the image forming apparatus 201. When the gloss imparting process (transparent toner layer assumption process) is started, the sheets P0 stacked on the manual feed section 4 are sequentially sent to the transfer position. Then, the transparent toner image is developed using the transparent toner supplied from the transparent toner supply unit 5S, and then transferred to the surface of the paper P0 by the intermediate transfer belt 6 and the secondary transfer unit 7, and transparent to the surface of the paper P0. A toner layer is formed. The paper P0 on which the transparent toner layer is formed is sent to the fixing unit 8, and after the transparent toner layer is assumed by the fixing unit 8, the paper P1 on which the transparent toner layer is assumed is discharged to the discharge unit 9. The At this stage, the surface of the paper P1 on which the transparent toner layer is assumed is in a so-called matte state with no gloss.

  Thereafter, the user stacks and arranges the paper P <b> 1 on the manual feed portion 21 of the gloss applying device 220. When the gloss applying process (gloss finishing process) is started, the sheets P1 stacked on the manual feed portion 21 are sequentially sent to the heating and pressing position. Then, the transparent toner layer that is supposedly attached to the surface of the paper P1 is heated and pressed by the pair of heating roller 22 and pressure roller 23 and is remelted. Next, the sheet P1 is conveyed in a state where the melted transparent toner layer is in contact with the surface of the belt member 24 having high smoothness, and the melted transparent toner layer of the sheet P1 is cooled by the cooling fans 25 and 26. Thereafter, the paper P2 to which the transparent toner layer is fixed is discharged to the discharge unit 29. Through such processing, the smoothness of the transparent toner layer is increased, so that the surface of the paper P2 is glossy.

JP 2010-186122 A

  Although the gloss application system applies gloss to the paper through the above-described processes, the paper P1 discharged from the image forming apparatus 201 and having the transparent toner layer formed thereon may be easily stuck. If the sheets P1 stick to each other, for example, it is difficult to spread and convey the sheets P1 one by one in the glossing device 220 or the post-processing apparatus in the next process. The reason for this is as follows.

(1) Since the colored toner is removed from the transparent toner, there is almost no metal component (for example, carbon or zinc) used as the colored component. For this reason, in the image forming apparatus, electric charges are likely to remain in the transparent toner layer formed on the paper during transfer, and static electricity is generated. Then, the sheets on which the transparent toner layer is supposedly attached are easily stuck to each other by the action of static electricity.
(2) Usually, a transparent resin is used as the material of the transparent toner, but due to its insulating property, electric charges tend to stay in the transparent toner layer formed on the paper. As a result, static electricity is generated, and the papers on which the transparent toner layer is assumed are easily stuck to each other.
(3) Further, examples of the gloss application include posters and photo books (general name for personal photo collection production services), but cardboard is often used compared to normal printing. In the case of thick paper, it is difficult for charges to pass through the paper, and the volume in which charges are stored increases depending on the thickness, which contributes to the charge remaining on the paper.

  From the above situation, it is desired to prevent sticking between sheets on which a transparent toner layer is formed.

  An image forming apparatus according to an aspect of the present invention includes a transparent toner supply unit that supplies transparent toner, a transfer unit that transfers the transparent toner supplied from the transparent toner supply unit to a sheet, and a sheet that is conveyed from the transfer unit. A fixing unit that presupposes transparent toner, a separation sheet supply unit that supplies a separation sheet made of a sheet-like member, a sheet conveyed from the fixing unit, and a separation sheet supplied from the separation sheet supply unit are alternately discharged. A control unit that performs control as much as possible.

  According to the image forming apparatus of one aspect of the present invention, the separation sheet is inserted between the sheets on the conveyance path so that the sheet on which the transparent toner layer is assumed and the separation sheet are alternated, and thereby the sheet is discharged to the discharge unit. Sheets and separation sheets are stacked alternately.

  According to the present invention, since the separation sheet is interposed between the discharged sheets, it is possible to prevent the sheets having the transparent toner layer from sticking to each other.

It is explanatory drawing which shows the outline | summary of the glossiness provision system using the image forming apparatus and glossiness provision apparatus based on the 1st Embodiment of this invention. 2 is a block diagram illustrating a control system of the image forming apparatus. FIG. 3 is a flowchart illustrating an operation example of the image forming apparatus illustrated in FIG. 2. It is explanatory drawing which shows the example in case a transparent toner layer is a frame-shaped pattern. FIG. 10 is an explanatory diagram illustrating an example in a case where the transparent toner layer has a pattern extending linearly in the sheet passing direction. An example in which the transparent toner layer is a pattern having a partially collected shape (area) is shown. It is explanatory drawing which shows an example of a separation sheet. It is a schematic block diagram which shows an example of the image forming system comprised from the image forming apparatus and glossiness provision apparatus based on the 2nd Embodiment of this invention. It is explanatory drawing which shows the outline | summary of the glossiness provision system using the conventional image forming apparatus and glossiness grant apparatus.

Hereinafter, an example of an embodiment for carrying out the present invention (hereinafter also referred to as an embodiment) will be described with reference to the accompanying drawings. The description will be given in the following order. In addition, in each figure, the same code | symbol is attached | subjected to the common component and the overlapping description is abbreviate | omitted.
1. First Embodiment (Example in which a separation sheet is inserted between sheets and discharged)
2. Second Embodiment (Example in which a separation sheet is inserted between sheets and discharged through a glossy finishing process)
3. Other (various variations)

<1. First Embodiment>
An image forming apparatus according to a first exemplary embodiment of the present invention will be described. The image forming apparatus according to the first exemplary embodiment includes a separation sheet storage unit in addition to a normal sheet storage unit, and appropriately supplies the separation sheets stored in the separation sheet storage unit under predetermined conditions.

[Outline of Glossing System Using Image Forming Apparatus and Glossing Apparatus]
FIG. 1 is an explanatory diagram showing an outline of a gloss applying system using an image forming apparatus and a gloss applying apparatus according to a first embodiment of the present invention. In FIG. 1, a part considered to be mainly necessary for the description of the present invention is extracted from the configuration of the image forming apparatus.

  As shown in FIG. 1, an image forming apparatus 1 forms an image on a sheet by an electrophotographic method. For example, a sheet storage unit 2A, an image forming unit 5, an intermediate transfer belt 6, and a secondary transfer unit. 7 and a fixing unit 8. The image forming unit 5 includes four image forming units 5Y, 5M, 5C, and 5K in order to form toner images of four colors, for example, yellow (Y), magenta (M), cyan (C), and black (Bk). It has.

  Further, above the image forming unit 5, a transparent toner supply unit 5 </ b> S that supplies transparent toner made of, for example, a transparent resin used for glossing is provided. The transparent toner generally has a property of being insulative or weak in electrical conductivity since a colorant component (metal component) is removed from the colored toner. Further, the lower part of the image forming apparatus 1 includes a separation sheet storage unit 2B for storing separation sheets and a separation sheet supply unit 3B in addition to the normal sheet storage unit 2A. Here, the description of the paper feed unit for feeding the paper stored in the paper storage unit 2A is omitted.

  Separation sheets are used for the purpose of preventing sheets with a transparent toner layer from adhering to each other after discharge, so that sheets with a transparent toner layer post-discharge and separation sheets are alternately stacked. Inserted and discharged alternately with paper. As the separation sheet, a sheet-like member is used, and it is desirable that the separation sheet be a conductive sheet from the viewpoint of preventing electric charges from staying in the transparent toner layer. Details of the insertion of the separation sheet between the sheets will be described later. In the present specification, the force that causes the sheets to stick to each other may be referred to as an adsorption force.

In addition, an environmental sensor 33 is installed in an arbitrary place of the image forming apparatus 1, for example, in the vicinity of the secondary transfer unit 7.
The environment sensor 33 includes, as an example, functions of a thermometer that measures temperature and a hygrometer that measures humidity, performs measurement according to a predetermined timing or instruction, and outputs information on the measured temperature and humidity. The environmental sensor 33 is preferably installed, for example, in the vicinity of the secondary transfer unit 7 or in the vicinity of the conveyance path between the secondary transfer unit 7 and the discharge unit 29.

  Although the configuration of the image forming apparatus 1 according to the present embodiment is a well-known configuration except for the separation sheet storage unit 2B and the separation sheet supply unit 3B for the separation sheet, the configuration has been briefly described. For example, refer to Japanese Patent Application Laid-Open No. 2010-186122.

  On the other hand, the gloss applying device 20 includes, for example, a pair of a heating roller 22 and a pressure roller 23 (heating and pressing device), a belt member 24, cooling fans 25 and 26, and a plurality of conveying rollers. The gloss imparting device 20 includes a separation sheet detection unit 27 and a separation sheet removal unit 28.

  The separation sheet detection unit 27 is disposed in the vicinity of the conveyance path and detects the separation sheet conveyed on the conveyance path. As the separation sheet detection unit 27, an optical sensor, an ultrasonic sensor, or the like is used. Alternatively, an image sensor (camera) may be used for the separation sheet detection unit 24, and an image processing technique may be applied to an image captured by the image sensor to detect the separation sheet.

  The separation sheet removing unit 28 removes the separation sheet being conveyed on the conveyance path from the conveyance path. As an example of the removal method, an insertion portion (not shown) of the separation sheet removal unit 28 is inserted into a hole provided in the separation sheet, which will be described later, and the separation sheet is pulled from the conveyance path so that the separation sheet is hooked by the insertion portion. Remove.

  The configuration of the gloss imparting device 20 according to the present embodiment has been described briefly because it is a well-known configuration except for the separation sheet detection unit 27 and the separation sheet removal unit 28, but in more detail, for example, See Japanese Patent Application Laid-Open No. 2010-186122.

[Flow of glossing in the glossing system]
First, a user stacks and arranges sheets P0 on which images are formed on the manual feed portion 4 of the image forming apparatus 1. When the gloss imparting process (transparent toner layer assumption process) is started, the sheets P0 stacked on the manual feed portion 4 are sequentially sent to the transfer position via the transport path 11.

  On the other hand, a photosensitive member (not shown) included in the transparent toner supply unit 5S is charged and erased and exposed in accordance with the original image to form an electrostatic latent image on the photosensitive member. A transparent toner is attached to the electrostatic latent image on the photoconductor using a developing unit to form a transparent toner image.

  Then, the transparent toner attached to the photosensitive member is transferred (primary transfer) to the intermediate transfer belt 6, and the transparent toner attached to the intermediate transfer belt 6 is applied to the paper P 0 on which an image is formed by the secondary transfer unit 7. Transfer (secondary transfer).

  The paper P0 having the transparent toner layer formed on the surface is sent to the fixing unit 8, and after the transparent toner layer is assumed by the fixing unit 8, the paper P1 on which the transparent toner layer is assumed is applied to the discharge unit 9. Discharged. At this stage, the surface of the paper P1 on which the transparent toner layer is presumed is in a so-called matte state with no gloss.

  In synchronism with the formation of the transparent toner layer on the sheet P0 and the process of assumed attachment, the separation sheet S stored in the separation sheet storage unit 2B is supplied by the separation sheet supply unit 3B. In FIG. 1, the conveyance path 12 that conveys the separation sheet S and the conveyance path 11 that conveys the paper merge before the conveyance unit 32 (upstream side). Therefore, the supplied separation sheet S merges from the conveyance path 12 to the conveyance path 11 and is conveyed to the conveyance unit 32. At this time, when the separation sheet S is inserted between the sheets P0 on the transport path 11 so that the sheet P0 and the separation sheet S are alternated, and when the sheet P1 and the separation sheet S are discharged to the discharge unit 9, The sheets P1 and the separation sheets S are alternately stacked.

  After that, the user places the paper P1 with the separation sheet S inserted between the papers in the manual feed portion 21 of the gloss applying device 20. When the gloss applying process (gloss finishing process) is started, the paper P1 and the separation sheet S that are alternately stacked on the manual feed portion 21 are sequentially sent to the heating and pressing position. Then, the transparent toner layer assumed on the surface of the paper P1 is heated and pressed by the pair of heating roller 22 and pressure roller 23, and is remelted. Next, the sheet P1 is conveyed in a state where the melted transparent toner layer is in contact with the surface of the belt member 24 having high smoothness, and the melted transparent toner layer of the sheet P1 is cooled by the cooling fans 25 and 26. Thereafter, the paper P2 to which the transparent toner layer is fixed is discharged to the discharge unit 29. Through such processing, the smoothness of the transparent toner layer is increased, so that the surface of the paper P2 is glossy.

  On the other hand, the separation sheet S conveyed into the gloss applying device 20 is detected by the separation sheet detection unit 27. When the separation sheet S is detected by the separation sheet detection unit 27, the CPU 101 operates the separation sheet removal unit 28 to remove the separation sheet S from the conveyance path.

  In FIG. 1, an example in which the conveyance path 12 that conveys the separation sheet S and the conveyance path 11 that conveys the sheet merge before the conveyance unit 32 is described, but the present invention is not limited to this example. The separation sheet S is inserted between the sheets P0 on the conveyance path so that the sheets P0 and the separation sheets S are alternated at an arbitrary position in the image forming apparatus, and finally separated from the sheet P1 discharged to the discharge unit 9. The sheets S may be stacked alternately. Alternatively, the sheet P1 and the separation sheet S may be simply discharged to the discharge unit 9 alternately from separate transport paths without inserting the separation sheet S between the sheets P0 on the transport path in the image forming apparatus.

[Hardware configuration example of image forming apparatus]
Next, the hardware configuration of each part of the image forming apparatus 1 of this example will be described with reference to FIG.

FIG. 2 is a block diagram illustrating a control system of the image forming apparatus according to the present embodiment.
As shown in FIG. 2, the image forming apparatus 1 includes, for example, a CPU (Central Processing Unit) 101 and a ROM (Read Only Memory) 102 for storing programs executed by the CPU 101, data, and the like. The data stored in the ROM 102 includes, for example, a predetermined condition (threshold value) assumed to cause a certain level or more of an attractive force between sheets supplied with transparent toner, a primary transfer output and a secondary during image formation. There are transfer output values. Note that, as the ROM 102, for example, a programmable ROM that is normally electrically erasable is used.

  The image forming apparatus 1 also includes a RAM (Random Access Memory) 103 used as a work area of the CPU 101, a hard disk drive (HDD) 104 as a mass storage device, and an operation display unit 105.

  The CPU 101 is an example of a condition determination unit and a control unit, and controls the entire apparatus in addition to determining whether separation sheet supply is necessary and controlling separation sheet supply. The CPU 101 is connected to a ROM 102, a RAM 103, an HDD 104, and an operation display unit 105 via a system bus 107, respectively. The CPU 101 also connects the system bus 107 to the image reading unit 31, the image processing unit 106, the image forming unit 5, the transparent toner supply unit 5 </ b> S, the separation sheet supply unit 3 </ b> B, the conveyance unit 32, the secondary transfer unit 7, and the environment sensor 33. Connected through.

  The HDD 104 is a large-capacity storage device that stores image data of an original image obtained by reading by the image reading unit 31 and stores output image data and the like.

  The operation display unit 105 is a touch panel including a display such as a liquid crystal display (LCD) or an organic ELD (Electro Luminescence Display) and a touch sensor (an example of an operation unit). The operation display unit 105 displays an instruction menu for the user, information about the acquired image data, and the like. Further, the operation display unit 105 includes a plurality of keys, and receives input of various instructions, data such as characters and numbers by a user's key operation, and outputs an input signal.

  The image reading unit 31 optically reads a document image and converts it into an electrical signal. Image data generated by the image reading unit 31 and image data transmitted from a PC (Personal Computer) 120 showing an example of an external device connected to the image forming apparatus 1 are sent to the image processing unit 106 for image processing. Is done. The image processing unit 106 performs processes such as analog processing, A / D conversion, shading correction, and image compression on the received image data.

  The image forming unit 5 receives the image data processed by the image processing unit 106 and forms an image on a sheet.

  The separation sheet supply unit 3B supplies the separation sheet stored in the separation sheet storage unit 2B to the conveyance path 12 based on a command from the CPU 101.

  The secondary transfer unit 7 performs secondary transfer based on the bias value (secondary transfer output) at the time of secondary transfer stored in the ROM 102 or a value instructed by the CPU 101.

  In this example, an example in which a personal computer is applied as an external device has been described. However, the present invention is not limited to this, and various other devices such as a facsimile device can be applied as the external device.

[Operation example of image forming apparatus]
Next, an operation example of the image forming apparatus 1 will be described.
The supply of the separation sheet and the alternate discharge with the printed matter on which the transparent toner layer is assumed are assumed to cause the CPU 101 (condition determination unit) to exert a certain level of adsorption force between the sheets on which the transparent toner is assumed. It is executed when it is determined that the predetermined condition is satisfied.

FIG. 3 is a flowchart illustrating an operation example of the image forming apparatus 1.
First, when the gloss imparting process (transparent toner layer assumption process) is started, the CPU 101 determines whether or not the content of the print setting is a print setting for forming the transparent toner layer on both sides of the paper (step S1). . If the print setting is duplex printing, the process proceeds to step S6.

  When sheets with a transparent toner layer formed on only one side are stacked, residual charge exists only on one of the opposing sides of the two sheets. However, when sheets having a transparent toner layer formed on both sides of the sheet are stacked, residual charges exist on both opposing surfaces of the two sheets. Therefore, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other.

  If it is determined in step S1 that the printing is not duplex printing, the CPU 101 determines whether or not the image formation rate by the transparent toner layer that is supposedly attached to the sheet is equal to or greater than a predetermined threshold (step S2). When the image forming rate is equal to or higher than the predetermined rate, that is, when the image forming rate is high, the process proceeds to step S6.

  Here, the image formation rate is a ratio between the area of the paper and the area of the transparent toner layer formed by the transparent toner fixed on the paper. The higher the image formation rate of the transparent toner layer that is supposedly attached to the paper, the more transparent toner layers exist on the paper surface, and the number of staying charges tends to increase. Therefore, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other.

  If it is determined in step S2 that the image formation rate is not equal to or greater than the threshold, the CPU 101 determines whether the transparent toner layer has a predetermined image formation pattern (step S3). If the transparent toner layer matches the predetermined image forming pattern, the process proceeds to step S6.

  When the transparent toner layer has a predetermined image forming pattern, the area of the transparent toner layer becomes large depending on the image forming pattern, so that the accumulated charge tends to increase. Therefore, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other. Further, depending on the form of the image forming pattern, the frictional force generated between one of the stacked sheets (transparent toner layer) and the other sheet (transparent toner layer) becomes large, so that it is difficult to spread the stacked sheets.

  If it is determined in step S3 that the transparent toner layer is not a predetermined image formation pattern, the CPU 101 determines whether the target paper on which the transparent toner layer is to be formed is equal to or greater than a predetermined basis weight (step S4). If the paper is not less than the predetermined basis weight, that is, if it is a thick paper, the process proceeds to step S6.

  When the paper has a predetermined basis weight or more (thick paper), it is difficult for electric charges to pass through the paper, and the volume in which electric charges can be stored is increased depending on the thickness. Therefore, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other. Further, since the weight of the sheet itself increases, for example, when the sheets are stacked, the frictional force acting between the stacked sheets is increased, and the stacked sheets are hardly scattered.

  If it is determined in step S4 that the sheet is not equal to or more than the predetermined basis weight, the CPU 101 determines whether the humidity inside the image forming apparatus is equal to or lower than a threshold, that is, low humidity (step S5). If the humidity is equal to or lower than the threshold value, that is, the humidity is low, the process proceeds to step S6.

  When the humidity is low, as is well known, static electricity tends to stay in an object (for example, a transparent toner layer). Increasing the humidity increases the amount of adsorbed moisture on the surface of the material, thereby improving the electrical conductivity of the surface of the material and increasing the rate of charge leakage, but the opposite is true when the humidity is low. Therefore, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other.

  When it is determined in step S5 that the humidity is not equal to or lower than the threshold, the CPU 101 ends the process of this flowchart without supplying the separation sheet.

  On the other hand, the print setting is double-sided printing (YES in step S1), the image forming rate is equal to or higher than a predetermined ratio (YES in step S2), and the transparent toner layer is a predetermined image forming pattern (YES in step S3). When the sheet is equal to or more than the predetermined basis weight (YES in step S4) and the humidity is equal to or lower than the threshold value (YES in step S5), the CPU 101 causes the operation display unit 105 to display the separation sheet. A menu screen is displayed that allows the user to select whether or not to apply the separation sheet insertion mode for supplying. When the user operates the operation display unit 105 to select the separation sheet insertion mode, the CPU 101 receives an input signal output from the operation display unit 105 and determines that the separation sheet insertion mode has been selected (step). S6).

  When the separation sheet insertion mode is selected, the CPU 101 controls the separation sheet supply unit 3B to supply the separation sheet S stored in the separation sheet storage unit 2B (step S7).

  Then, the CPU 101 controls so that the supplied separation sheet S is transported through the transport path 12 and inserted between the sheets P0 transported through the transport path 11 at the junction with the transport path 11. As a result, the sheets P0 and the separation sheets S are alternately arranged on the conveyance path and are alternately conveyed, and are alternately stacked when discharged to the discharge unit 9.

  If the user does not select the separation sheet insertion mode in step S6, the CPU 101 does not switch to the separation sheet insertion mode and does not supply the separation sheet S. Alternatively, when YES is selected in any of steps S1 to S5, the CPU 101 may supply the separation sheet S without confirming the selection of the separation sheet insertion mode.

[Pattern of transparent toner layer]
Here, an example in which the transparent toner layer corresponds to a predetermined image forming pattern, which is one of the conditions for supplying the separation sheet (step S5 in FIG. 3), will be described.

FIG. 4 shows an example in which the transparent toner layer has a frame-like pattern.
In this example, a frame-shaped transparent toner layer 41 is formed on the surface of the paper P1. First, in the case of a frame shape, since a frame line is formed in the vicinity of the four sides of the paper, it is difficult to spread the stacked paper. It has been empirically found that when a transparent toner layer is formed on the edge of the paper, it is difficult to scratch the paper. In addition, when the transparent toner layer has a frame shape, the area of the transparent toner layer is increased to some extent, so that the same effect as when the transparent toner layer has a high image formation rate is produced. For the above reasons, it is desirable to supply a separation sheet when the transparent toner layer is formed in a frame shape on the paper.

FIG. 5 shows an example in which the transparent toner layer has a pattern extending linearly in the sheet passing direction.
In this example, three transparent toner layers 42a, 42b, and 42c extending linearly in the sheet passing direction are formed on the surface of the paper P1. The transparent toner layer 42a is positioned near the left end of the sheet P1, the transparent toner layer 42b is positioned near the center of the sheet, and the transparent toner layer 42c is positioned near the right end of the sheet P1. If the transparent toner layer is formed in a linear shape, the frictional force in the direction along the line tends to increase. Therefore, when the other sheet is rolled from the stacked one sheet, if the direction in which the other sheet is shifted is a direction along the line, the frictional force is large and hardly spread. For the above reasons, it is desirable to supply a separation sheet when the transparent toner layer is formed on the sheet so as to extend linearly in the sheet passing direction.

  Note that the frame-like pattern shown in FIG. 4 is included in one of the pattern examples corresponding to this example because a part thereof extends linearly in the sheet passing direction.

FIG. 6 shows an example where the transparent toner layer is a pattern having a partially collected shape (area).
In this example, four transparent toner layers 43a, 43b, 43c, and 43d having a certain size are formed on the surface of the paper P1. Transparent toner layers 43a and 43b are formed at positions oblique to each other above the sheet P1, and transparent toner layers 43c and 43d are formed below the transparent toner layers 43a and 43b. When one transparent toner layer has a certain size (area), static electricity generated in one transparent toner layer increases, and when there are a plurality of transparent toner layers having a certain size, they occur on the entire sheet. Static electricity increases. For this reason, the adsorption force due to static electricity between the sheets increases, and the sheets tend to stick to each other. For the above reasons, it is desirable to supply a separation sheet when the transparent toner layer is formed in a partially integrated shape (area) on the paper.

  In the example of FIG. 6, the transparent toner layers 43a and 43c and the transparent toner layers 43b and 43d are positioned along the sheet passing direction, respectively. Even when the transparent toner layers are scattered in this way, they exist along the paper passing direction, and thus are included in one of the pattern examples corresponding to the example of FIG.

[Example of separation sheet]
As described with reference to FIG. 1, the separation sheet inserted between sheets may be removed in the glossing step or other steps. Assuming such a case, an example of a preferable form of the separation sheet will be described.

FIG. 7 is an explanatory diagram illustrating an example of a separation sheet.
In the example of FIG. 7, two holes 44-1 and 44-2 are provided in a part of the separation sheet S. The holes 44-1 and 44-2 are used when the separation sheet S is removed from the alternately stacked sheets P1. As shown in FIG. 7 in which the paper P1 is ejected and stacked on the separation sheet S, the holes 44-1 and 44-2 are formed in a region of the separation sheet S that does not overlap the paper P1 when viewed from above. Has been.

  In the gloss applying device 20 of FIG. 1, the separation sheet removing unit 28 uses the holes 44-1 and 44-2 provided in the separation sheet S before giving gloss to the paper P1 on which the transparent toner is assumed. Thus, the separation sheet S is removed from between the sheets P1.

  In this example, the separation sheet S is formed so as to protrude from the upstream side and the downstream side in the sheet passing direction with respect to the paper P1, but it is sufficient that at least a part thereof protrudes. As described above, the separation sheet S can be hooked and removed by making a hole in the protruding portion and inserting the insertion portion of the separation sheet removing portion 28 into the hole. Alternatively, for example, a picking part (not shown) may be provided in the separation sheet removing unit, and the separation sheet S may be removed by picking the protruding part with the picking part.

  According to the first embodiment described above, when the separation sheet is inserted between the sheets on the conveyance path so that the sheet on which the transparent toner layer is assumed and the separation sheet are alternated, and thereby discharged to the discharge unit. Sheets and separation sheets are alternately stacked. That is, a separation sheet is interposed between the discharged sheets. Therefore, the adsorbing force that acts due to the residual charge (static electricity) of the transparent toner layer is suppressed between the sheets on which the transparent toner layer is formed, and the sheets can be prevented from sticking to each other.

<2. Second Embodiment>
The second embodiment is an example in which an image forming system is configured by combining the image forming apparatus according to the first embodiment and a gloss imparting apparatus. That is, in this embodiment, the separation sheet is inserted between the sheets in the image forming apparatus and supplied to the glossing apparatus, and after the glossing process (gloss finishing process) is performed by the glossing apparatus, the sheet and the separation sheet are discharged. To do.

FIG. 8 is a schematic configuration diagram illustrating an example of an image forming system including an image forming apparatus and a gloss imparting apparatus according to the second embodiment of the present invention.
The image forming system 50 of the present example includes the image forming apparatus 1 and a gloss applying device 20A. The gloss imparting device 20A has the same configuration as the gloss imparting device 20 except that the gloss imparting device 20 (FIG. 1) does not include the manual feed unit 21, the separation sheet detection unit 27, and the separation sheet removal unit 28. It is.

Hereinafter, the flow of glossing in the image forming system 50 will be described.
The gloss imparting process (transparent toner layer assumption process) by the image forming apparatus 1 is the same as in the first embodiment. A user stacks and arranges sheets P0 on which images are formed on the manual feed portion 4 of the image forming apparatus 1. When the gloss imparting process (transparent toner layer assumption process) is started, the sheets P0 stacked on the manual feed portion 4 are sequentially sent to the transfer position via the transport path 11. The image forming apparatus 1 performs the development of the transparent toner image, the transfer to the paper P0, and the assumed attachment, and discharges the paper P1 on which the transparent toner layer is assumed, to the gloss imparting device 20A. At this time, when satisfying a predetermined condition that is assumed that an adsorption force of a certain level or more acts between the sheets P1, the image forming apparatus 1 inserts the separation sheet S between the sheets P1 conveyed on the conveyance path 11, The paper P1 and the separation sheet S are discharged alternately.

  When the sheet P1 and the separation sheet S are alternately supplied from the image forming apparatus 1, the gloss imparting apparatus 20A starts a gloss imparting process (gloss finishing process). The gloss imparting device 20A remelts the transparent toner layer that is assumed on the surface of the paper P1, cools the belt member 24 while increasing its smoothness, and fixes the transparent toner layer to the paper P1. Then, the paper P2 to which the transparent toner layer is fixed is discharged to the discharge unit 29.

  In this way, the paper P1 and the separation sheet S are alternately supplied from the image forming apparatus 1 to the gloss applying device 20A, and the paper P2 and the separation sheet S are alternately discharged as they are through the gloss finishing processing of the gloss applying device 20A. . Then, when discharged to the discharge unit 29, the paper P2 and the separation sheet S are alternately stacked.

  According to the second embodiment described above, the gloss forming apparatus connected to the image forming apparatus is supplied with sheets and separation sheets alternately from the image forming apparatus. And the separation sheets are alternately discharged and stacked. Accordingly, the adsorption force acting on the residual charge (static electricity) of the transparent toner layer is suppressed between the sheets on which the transparent toner layer is formed, and the sheets can be prevented from sticking to each other. Therefore, in a subsequent process of the gloss imparting apparatus, for example, a post-process such as a cutting process or a punching process, it becomes easy to spread the paper on which the transparent toner layer is formed, and the post-process can be performed accurately.

<3. Other>
In the second embodiment described above, the separation sheet S is not removed by the gloss applying device 20A, and the sheet P2 and the separation sheet S are alternately discharged through the gloss finishing process. However, the present invention is not limited to this example. For example, the gloss applying device 20A includes a separation sheet detection unit 27 and a separation sheet removal unit 28 (see FIG. 1), and is separated immediately after the paper P1 and the separation sheet S are supplied from the image forming device 1 (before the glossy finishing process). The sheet S may be removed and only the paper P2 that has been subjected to the glossy finishing process may be discharged. Alternatively, the separation sheet S may be removed between the gloss finishing device 20 </ b> A and after the gloss finish processing until discharging.

  Further, in the gloss applying device 20 according to the first embodiment described above, the separation sheet removal unit 28 picks up holes provided in a partial area of the separation sheet S or a partial area thereof, thereby separating the sheet S. Although the example which removes was demonstrated, it is not restricted to this example. For example, when the separation sheet S is detected by the separation sheet detection unit 27, the separation sheet S may be removed by adopting a configuration in which the separation sheet S is guided to a conveyance path different from the conveyance path of the paper P1. The same applies to the gloss applying device 20A according to the second embodiment.

  Further, in the first and second embodiments described above, an example is described in which the paper P0 on which the transparent toner layer is assumed is laminated and disposed on the manual feed portion 4 of the image forming apparatus 1 and the glossing process is executed. However, it is not limited to this example. For example, after an image is formed on the paper stored in the paper storage unit 2A by the image forming unit 5, the transparent toner is supplied and assumed on the paper (corresponding to the paper P0) on which the image is formed, and the transparent toner layer May be discharged alternately (corresponding to the sheet P1) and the separation sheet S.

  Further, depending on the configuration of the separation sheet removing unit 28 of the gloss applying device 20, the separation sheet detecting unit 27 can be omitted. For example, the insertion portion of the separation sheet removing unit 28 is in contact with the paper P1 and the separation sheet S that are alternately conveyed. When the leading end of the insertion portion is inserted into the holes 44-1 and 44-2 provided in the separation sheet S being conveyed, the separation sheet removing portion 28 hooks the separation sheet S by detecting it. Configure to perform the removal action. Alternatively, the separation sheet removing unit 28 performs the separation sheet removing operation on the transported paper P1 and the separation sheet S each time, and for example, only when there is a protruding area such as the separation sheet S shown in FIG. The separation sheet S may be removed.

  In the first and second embodiments described above, the CPU 101 reduces the value of the secondary transfer output (for example, transfer current) of the secondary transfer unit 7 when the separation sheet S passes through the secondary transfer unit 7. Yes (including zero). By reducing the value of the secondary transfer output of the secondary transfer unit 7, the residual charge of the paper P0 onto which the transparent toner image is transferred can be suppressed, and the paper can be prevented from sticking to each other. Although the transfer current has been described as an example of the secondary transfer output, a transfer voltage may be used.

  Furthermore, in the first and second embodiments described above, the present invention has been described by taking the image forming apparatus 1 that forms a color image as an example. However, the present invention has means for assuming a transparent toner layer on a sheet. Any image forming apparatus may be used, and the present invention can also be applied to an image forming apparatus that forms a black and white image.

  In the first and second embodiments described above, the example of the image forming apparatus 1 including the intermediate transfer belt 6 (intermediate transfer body) has been described. However, the image forming apparatus performs transfer without using the intermediate transfer body. Is also applicable.

  Further, in this specification, the processing steps describing time-series processing are not limited to processing performed in time series according to the described order, but are not necessarily performed in time series, either in parallel or individually. The processing (for example, parallel processing or object processing) is also included.

  As mentioned above, this invention is not limited to each embodiment mentioned above, Of course, unless it deviates from the summary described in the claim, various other modifications and application examples can be taken. .

  DESCRIPTION OF SYMBOLS 1 ... Image forming apparatus, 2B ... Separation sheet storage part, 3B ... Separation sheet supply part, 4 ... Manual feed part, 5 ... Image formation part, 5Y, 5M, 5C, 5K ... Image formation unit, 5S ... Transparent toner supply part 8 ... Fixing device 9 ... Discharging unit 20, 20A ... Glossing device 21 ... Manual feeding unit 27 ... Separating sheet detecting unit 28 ... Separating sheet removing unit 29 ... Discharging unit 32 ... Conveying unit 33 ... environmental sensor, 101 ... CPU, 105 ... operation display, P0 ... paper (image is formed), P1 ... paper after assumption of transparent toner, P2 ... paper after transparent toner fixing, S ... Separation sheet

Claims (13)

A transparent toner supply unit for supplying transparent toner;
A transfer unit that transfers the transparent toner supplied from the transparent toner supply unit to a sheet;
A fixing unit for fixing the transparent toner to the sheet conveyed from the transfer unit;
A separation sheet supply unit for supplying a separation sheet made of a sheet-like member;
An image forming apparatus comprising: a control unit that performs control to alternately discharge the sheet conveyed from the fixing unit and the separation sheet supplied from the separation sheet supply unit. A condition determining unit that determines whether or not a predetermined condition that is assumed to cause an adsorption force of a certain level or more to act between the sheets on which the transparent toner is fixed;
The image forming apparatus according to claim 1, wherein when the condition determining unit determines that the predetermined condition is satisfied, the control unit performs control to alternately discharge the sheet and the separation sheet. The image forming apparatus according to claim 1, wherein the predetermined condition is that the transparent toner is fixed on both sides of the sheet. The image forming apparatus according to claim 2, wherein the predetermined condition is that an area of the transparent toner layer formed by the transparent toner fixed on the paper with respect to an area of the paper is equal to or greater than a predetermined ratio. The image forming apparatus according to claim 2, wherein the predetermined condition is that a transparent toner layer formed by the transparent toner supplied to the paper matches a predetermined pattern. The image forming apparatus according to claim 2, wherein the predetermined condition is that a basis weight of the sheet is equal to or greater than a threshold value. Further equipped with a hygrometer,
The image forming apparatus according to claim 2, wherein the predetermined condition is that a humidity measured by the hygrometer is equal to or less than a threshold value. The image forming apparatus according to claim 1, wherein the separation sheet has a region that does not overlap the sheet in a top view after being discharged. The image forming apparatus according to claim 8, wherein the separation sheet has a hole for removing the separation sheet from the alternately stacked sheets in a region that does not overlap with the sheet in the top view. . The image forming apparatus according to claim 1, wherein the control unit reduces a transfer output value of the transfer unit when the separation sheet passes through the transfer unit. The image forming apparatus according to claim 1, wherein the sheet-like member used as the separation sheet is a conductive sheet. An operation unit that generates an input signal according to a user operation;
The image forming apparatus according to claim 1, wherein the control unit performs control to alternately discharge the sheet and the separation sheet based on an input signal from the operation unit. An image forming apparatus that forms a transparent toner layer on a sheet, and a gloss imparting apparatus that imparts gloss to the sheet supplied from the image forming apparatus,
The image forming apparatus includes:
A transparent toner supply unit for supplying the transparent toner;
A transfer unit that transfers the transparent toner supplied from the transparent toner supply unit to the paper;
A fixing unit for fixing the transparent toner to the sheet conveyed from the transfer unit;
A separation sheet supply unit for supplying a separation sheet made of a sheet-like member;
An image forming system comprising: a control unit that performs control to alternately discharge the sheet conveyed from the fixing unit and the separation sheet supplied from the separation sheet supply unit to the gloss applying device.