JP2019015874A - Image forming apparatus, image forming method, and program - Google Patents

Abstract

To enable a user to control glossiness of an image without causing an increase in size and cost of an image forming apparatus.SOLUTION: An image forming apparatus comprises: an image forming unit 10 that forms toner images on a sheet P; a fixing device 20 that performs fixing processing of applying heat and pressure to the toner image formed on the sheet P by the image forming unit 10 to fix the toner image; an image forming path R1 that conveys the sheet P to the image forming unit 10 and fixing device 20; a circulation path R3 that branches from the image forming path R1 downstream in a sheet conveyance direction of the fixing device 20 and merges into the image forming path R1 to circulate the sheet such that an image is formed on the same face of the sheet P upstream in the sheet conveyance direction of the image forming unit 10; and a control unit 11 that executes glossiness adjustment processing of circulating the sheet P to which the toner image is fixed by the fixing device 20 on the circulation path R3 and applying heat and pressure with the fixing device 20 without forming an image with the image forming unit 10 to adjust glossiness.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus, an image forming method, and a program.

Conventionally, an image forming unit that transfers a toner image formed on a photosensitive drum onto a sheet via an intermediate transfer belt, and a fixing unit that heats and pressurizes the sheet onto which the toner image is transferred to fix the toner image on the sheet. There is known an image forming apparatus including the above.
In recent years, in such an image forming apparatus, there is a demand for controlling the gloss of an image in order to further improve the image quality. On the other hand, for example, in Patent Document 1, in a tandem fixing type image forming apparatus in which a plurality of fixing units are arranged in the sheet conveyance direction and sheets are sequentially passed through the plurality of fixing units, the first fixing unit includes: A technique has been proposed in which the fixing property is secured and the image is glossed by the second fixing unit.

JP 2017-32842 A

  However, in Patent Document 1, since a plurality of fixing units are arranged, there is a problem in that the image forming apparatus is increased in size and cost.

  The present invention has been made in view of the above problems, and provides an image forming apparatus, an image forming method, and a program capable of controlling the gloss of an image without increasing the size and cost of the image forming apparatus. The purpose is to provide.

In order to solve the above-mentioned problem, the invention described in claim 1
An image forming unit for forming a toner image on paper;
A fixing unit that performs a fixing process of fixing the toner image formed on the paper by the image forming unit by heating and pressing; and
An image forming path for conveying paper to the image forming unit and the fixing unit;
Branch from the image forming path downstream of the fixing unit in the sheet conveying direction, and join the image forming path so that the image forming surface of the sheet becomes the same surface upstream of the image forming unit in the sheet conveying direction. A circulation path for circulating
Gloss adjustment processing is performed in which the sheet on which the toner image is fixed by the fixing unit is circulated through the circulation path, and the gloss is adjusted by heating and pressing by the fixing unit without image formation by the image forming unit. A control unit;
It is characterized by providing.

According to a second aspect of the present invention, in the image forming apparatus of the first aspect,
The control unit is characterized in that processing conditions including a heating temperature and a pressure force are varied in the fixing process and the gloss adjustment process.

According to a third aspect of the present invention, in the image forming apparatus according to the second aspect,
The controller is characterized in that the heating temperature of the gloss adjustment process is higher than the heating temperature of the fixing process.

According to a fourth aspect of the present invention, in the image forming apparatus according to any one of the first to third aspects,
The control unit sets processing conditions including a heating temperature and pressure in the fixing process and the gloss adjustment process according to the type and basis weight of the paper.

According to a fifth aspect of the present invention, in the image forming apparatus according to any one of the first to fourth aspects,
A gloss measuring unit for measuring the gloss of the paper on which the toner image is fixed by the fixing unit;
The control unit corrects processing conditions including a heating temperature and pressure in the gloss adjustment processing based on a measurement result of the gloss measurement unit.

According to a sixth aspect of the present invention, in the image forming apparatus according to any one of the first to fifth aspects,
The control unit executes the gloss adjustment processing when a gloss adjustment mode for adjusting gloss is selected.

The invention according to claim 7
An image forming unit that forms a toner image on a sheet, a fixing unit that performs fixing processing for fixing the toner image formed on the sheet by heating and pressurizing by the image forming unit, and the image forming unit and the fixing unit Branching from the image forming path transported in the paper and the image forming path downstream in the paper transport direction from the fixing unit, and the image forming surface of the paper is the same surface upstream in the paper transport direction from the image forming unit An image forming method in an image forming apparatus, comprising: a circulation path that joins an image forming path to circulate paper; and a control unit,
The control unit circulates the paper on which the toner image is fixed by the fixing unit through the circulation path, and adjusts the gloss by heating and pressing the fixing unit without forming an image by the image forming unit. The method includes a step of executing adjustment processing.

Further, the invention according to claim 8 is
An image forming unit that forms a toner image on a sheet, a fixing unit that performs fixing processing for fixing the toner image formed on the sheet by heating and pressurizing by the image forming unit, and the image forming unit and the fixing unit Branching from the image forming path transported in the paper and the image forming path downstream in the paper transport direction from the fixing unit, and the image forming surface of the paper is the same surface upstream in the paper transport direction from the image forming unit A circulation path for joining the image formation path and circulating the paper, and a computer of the image forming apparatus,
Gloss adjustment processing is performed in which the sheet on which the toner image is fixed by the fixing unit is circulated through the circulation path, and the gloss is adjusted by heating and pressing by the fixing unit without image formation by the image forming unit. This is a program for functioning as a control unit.

  According to the present invention, it is possible to control the gloss of an image without increasing the size and cost of the image forming apparatus.

1 is a configuration diagram schematically illustrating an image forming apparatus according to an exemplary embodiment. FIG. 2 is a block diagram schematically showing a configuration of a control system of the image forming apparatus in FIG. 1. It is a figure which shows an example of a setting table. 6 is a flowchart illustrating image forming processing executed in the present embodiment.

  Hereinafter, the present embodiment will be described in detail with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples.

[Configuration of Image Forming Apparatus 100]
First, the configuration of the image forming apparatus 100 in the present embodiment will be described.
FIG. 1 is a configuration diagram schematically illustrating an image forming apparatus 100 according to the present embodiment. The image forming apparatus 100 is an electrophotographic image forming apparatus 100 such as a copying machine, and forms a full-color image by arranging a plurality of photoconductors facing one intermediate transfer belt in the vertical direction. This is a so-called tandem color image forming apparatus.

  The image forming apparatus 100 mainly includes a document reading device SC, an image forming unit 10, a fixing device 20 as a fixing unit, an image reading unit 30 as a gloss measuring unit, a sheet conveying unit 40, and a control unit 11. It is housed in one housing.

  The document reader SC scans and exposes an image of the document with the optical system of the scanning exposure device, reads the reflected light with a line image sensor, and obtains an image signal. This image signal is subjected to processing such as A / D conversion, shading correction, and compression, and then input to the control unit 11 as image data. Note that the image data input to the control unit 11 is not limited to the data read by the document reading device SC. For example, the image data is received from a personal computer connected to the image forming device 100 or another image forming device by the communication unit 13. It may be what you did.

  The image forming unit 10 includes four sets of image forming units 10Y, 10M, 10C, and 10K, an intermediate transfer belt 6, a secondary transfer roller 8, and the like. The image forming units 10Y, 10M, 10C, and 10K are an image forming unit 10Y that forms a yellow (Y) image, an image forming unit 10M that forms a magenta (M) image, and an image that forms a cyan (C) image. The forming unit 10C includes an image forming unit 10K that forms a black (K) image.

  The image forming unit 10Y includes a photosensitive drum 1Y and a charging unit 2Y, an optical writing unit 3Y, a developing device 4Y, and a drum cleaner 5Y arranged around the photosensitive drum 1Y. Similarly, the image forming units 10M, 10C, and 10K include the photosensitive drums 1M, 1C, and 1K and charging units 2M, 2C, and 2K, optical writing units 3M, 3C, and 3K, and developing devices 4M, arranged around the photosensitive drums 1M, 1C, and 1K. 4C, 4K and drum cleaners 5M, 5C, 5K.

  The surfaces of the photosensitive drums 1Y to 1K are uniformly charged by the charging units 2Y to 2K, and latent images are formed on the photosensitive drums 1Y to 1K by scanning exposure by the optical writing units 3Y to 3K. Is done. Further, the developing devices 4Y to 4K develop latent images on the photosensitive drums 1Y to 1K by developing with toner. Thereby, a toner image of a predetermined color corresponding to any one of yellow, magenta, cyan, and black is formed on the photosensitive drums 1Y to 1K. The toner images formed on the photosensitive drums 1Y to 1K are sequentially transferred to predetermined positions on the rotating intermediate transfer belt 6 by primary transfer rollers 7Y, 7M, 7C, and 7K.

  The toner images of the respective colors transferred onto the intermediate transfer belt 6 are transferred by the secondary transfer roller 8 to the paper P that is conveyed at a predetermined timing by a paper conveying unit 40 described later. The secondary transfer roller 8 is a pressure contact member that forms a nip portion (hereinafter referred to as “transfer nip portion”) by being disposed in pressure contact with the intermediate transfer belt 6.

  The fixing device 20 is a device that performs a fixing process on the paper P on which the toner image is transferred, that is, the paper P sent out from the transfer nip portion. For example, a pair of fixing members (for example, a pair of rollers) and the fixing It is comprised with the heater which heats one or both of the members. The fixing device 20 fixes the toner image on the paper P through the action of the pressure applied by the pair of fixing members and the heat of the fixing member in the conveyance process of the paper P.

The image reading unit 30 includes, for example, a linear image sensor (for example, a CCD line sensor), an optical system, a light source, and the like. The image reading unit 30 reads the sheet P on which the toner image is transferred, and controls the obtained read image. 11 is output.
In this embodiment, the image reading unit 30 can measure the gloss of the toner image on the paper P, but is not particularly limited as long as at least the area of the paper P and the area of the toner image can be recognized. In the present embodiment, the image reading unit 30 is disposed downstream of the fixing device 20 and on the near side where the conveyance path is switched by the switching gate G, but downstream of the secondary transfer roller 8. The arrangement position is not particularly limited as long as it is a position where both sides (one side may be provided) of the paper P can be read.

The paper transport unit 40 transports the paper P along the transport path of the paper P.
The paper transport unit 40 includes an image forming path R1 for transporting the paper P to the image forming unit 10 and the fixing device 20, a switching gate G, a paper discharge path R2 for discharging the paper P after image formation to the outside, and a paper after image formation. A circulation path R3 for circulating P and an ADU inversion path R4 for forming images on both sides of the paper P are provided.

Each transport path is provided with a plurality of transport means for transporting the paper P. Each of the conveying means is composed of a pair of pressure-contacted rollers, and conveys the paper P when at least one of the rollers is rotationally driven through a driving mechanism mainly composed of an electric motor.
In addition, the pair of rollers constituting the individual conveying means is configured so that the state between the rollers can be switched between a pressure contact state and a separated state.
In addition to the configuration of the pair of rollers, the conveyance unit can widely employ a configuration including a pair of rotating members such as a combination of belts or a combination of a belt and a roller.

The image forming path R1 is a path for transporting the paper P from the paper feed tray to the switching gate G.
The paper P is accommodated in a paper feed tray 41 located in the lower part of the image forming apparatus 100, and the paper P accommodated in the paper feed tray 41 is taken in by the paper feed unit 42 and enters the image forming path R1. Sent out.
Alternatively, the paper P is stored in a paper feed tray included in a paper feed device (not shown) connected to the image forming apparatus 100, and the paper P held by the paper feed device forms an image from the paper feed device. It is supplied to the apparatus 100 and sent out to the image forming path R1.
The paper P may be placed on a manual feed tray provided in the image forming apparatus 100 and sent out to the image forming path R1.

  An image forming unit 10 and a fixing device 20 are provided on the image forming path R1. Further, in the image forming path R1, an intermediate conveyance roller 43, a loop roller 44, and a registration roller 45 are provided as conveyance means from the upstream side to the downstream side in the paper conveyance direction.

The sheet P is sequentially transported by the intermediate transport roller 43 and the loop roller 44 and travels through the image forming path R1. When the leading edge of the paper P approaches the registration roller 45, the paper P conveyed by the loop roller 44 or the like is abutted against the registration roller 45 in a rotation stopped state, and the loop roller 44 continues to rotate for a predetermined time. As a result, a loop is formed on the paper P. By this loop forming action, the bending of the leading edge of the paper P is corrected (skew correction).
Next, when the registration roller 45 starts to rotate at a predetermined timing so as to synchronize with the toner image carried by the intermediate transfer belt 6, the intermediate transport roller 43 and the loop roller 44 are switched from the pressure contact state to the separated state, The paper P is transported to the transfer nip portion of the image forming unit 10 only by the registration rollers 45, and then transported to the fixing device 20 by the secondary transfer roller 8. The sheet P on which the fixing process has been performed in the fixing device 20 is conveyed to the switching gate G.

The switching gate G is provided on the downstream side of the fixing device 20 in the sheet conveyance direction, and switches a path for conveying the sheet P conveyed from the image forming path R1. Specifically, the switching gate G guides the sheet P downward when the sheet P that has passed through the fixing device 20 is conveyed to the circulation path R3 or the ADU reversal path R4. The switching gate G moves the paper P straight when the paper P is transported to the paper discharge path R2.
Note that the switching gate G is normally in a state in which the paper P moves straight (sent to the paper discharge path R2). When the paper P is transported downward (sent to the paper discharge path R2 or the circulation path R3), it is driven by a drive unit (not shown) to transport the paper P downward and return to the original state.

  The paper discharge path R2 is a conveyance path for discharging the paper P that has been subjected to the fixing process by the fixing device 20 to a paper discharge tray 46 attached to the outer side surface of the housing.

The circulation path R3 is a transport path for returning the paper P, on which the fixing process has been performed by the fixing device 20, to the image forming path R1 again without changing the image forming surface (that is, without changing the front and back sides). It is.
The circulation path R3 branches from the downstream side of the sheet conveyance direction (position of the switching gate G) with respect to the image forming section 10 of the image forming path R1, and is arranged to reach a confluence 51 provided in the middle of the image forming path R1. ing.
In the circulation path R3, a reverse roller 47 and an intermediate transport roller 48 are provided as transport means from the upstream side to the downstream side in the transport direction of the paper P. The intermediate transport rollers 48 are arranged so as to be at a shorter interval than the length in the paper transport direction of the smallest paper P that passes therethrough.
The paper P supplied to the circulation path R3 is transported by the intermediate transport roller 48 and reaches the junction 51. The paper P that has reached the confluence 51 is sent out again to the image forming path R1.

The ADU reversal path R4 is a conveyance path for reversing the paper P, which has been subjected to the fixing process by the fixing device 20, to the image forming path R1 by reversing the front and back, and in the middle of the circulation path R3 (the paper of the reversing roller 47) Branching from an upstream position in the transport direction, and is arranged so as to reach a confluence 52 provided in the middle of the image forming path R1.
For example, when an image is formed on the back surface of the paper P, the paper P supplied to the circulation path R3 is reversed when the reverse roller 47 reverses at the timing when the reverse roller 47 sandwiches the rear end of the paper P. Then, it is conveyed from its rear end to the ADU reversing path R4 and reaches the confluence 52 of the image forming path R1. The paper P that has reached the junction 52 is sent out again to the image forming path R1.

Note that the image forming path R1, the circulation path R3, and the ADU reversing path R4 described above may be integrally configured so that they can be pulled out from the housing of the image forming apparatus 100.
At this time, the pair of rollers constituting the intermediate transport roller 48 may be divided so that only the upper roller is pulled out, or the upper and lower rollers may be pulled out together. In particular, if the upper and lower rollers are both pulled out, jam processing is facilitated, and the paper P can be prevented from being cut carelessly by the jam processing.

FIG. 2 is a block diagram schematically showing the configuration of the control system of the image forming apparatus 100 according to the present embodiment.
As shown in FIG. 2, the control unit 11 is connected to the storage unit 12, the communication unit 13, the operation unit 14, the document reading device SC, the image forming unit 10, the fixing device 20, the image reading unit 30, and the paper transport unit 40. ing.

The control unit 11 includes a CPU (Central Processing Unit), a RAM (Random Access Memory), and the like. The CPU of the control unit 11 reads the system program and various processing programs stored in the storage unit 12 and expands them in the RAM, and centrally controls the operations of the respective units of the image forming apparatus 100 according to the expanded programs.
For example, when a job execution command is input from the operation unit 14, the control unit 11 executes a job and controls to form an image on the paper P based on image data input from the document reading device SC or the communication unit 13. I do.
In the present exemplary embodiment, the control unit 11 circulates the paper P on which the toner image is fixed by the fixing device 20 through the circulation path R3, and the fixing device 20 does not perform image formation by the image forming unit 10. It is possible to execute a gloss adjustment process for adjusting the gloss by heating and pressing.

  The storage unit 12 is configured by a nonvolatile semiconductor memory, an HDD (Hard Disk Drive), or the like, and stores various programs executed by the control unit 11 as well as parameters and data necessary for each unit.

For example, the setting unit 121 is stored in the storage unit 12.
The setting table 121 is a table that stores setting values for setting processing conditions for fixing processing and gloss adjustment processing performed on the paper P by the fixing device 20 when the gloss adjustment processing is executed.

FIG. 3 is a diagram illustrating an example of the setting table 121.
In the example of FIG. 3, processing temperatures (processing conditions) in the fixing process and the gloss adjustment process are set according to the paper type and basis weight of the paper P.
That is, the setting table 121 includes items of “plain paper”, “rough paper”, and “coated paper” as paper types, and “60-80”, “81-120”, “121-210”, “ 211-350 "basis weight item. For each combination of the paper type and basis weight of the paper P, the processing temperature in the fixing process and the gloss adjustment process is set.

Note that the processing temperature (processing conditions) set here is merely an example, and it is possible to set the heating temperature of the gloss adjustment processing to be lower than the heating temperature of the fixing processing, or to set both to be the same. Of course it is possible.
Each setting value can be changed by, for example, a user operation via the operation unit 14.

  Here, the processing temperature (processing condition) is set according to the paper type and the basis weight of the paper P, but the processing temperature (processing condition) is set only according to either the paper type or the basis weight. The processing temperature (processing conditions) may be set using elements other than the paper type and the basis weight. Examples of elements other than the paper type and basis weight include coverage information for one side of the paper P, partial coverage information on the paper P, and the like.

  Returning to FIG. 2, the communication unit 13 includes various interfaces such as a NIC (Network Interface Card), a MODEM (Modulator-DEModulator), and a USB (Universal Serial Bus), and connects to an external device.

  The operation unit 14 outputs various information set by the user to the control unit 11. As the operation unit 14, for example, a touch panel capable of performing an input operation according to information displayed on the display can be used. Through the operation unit 14, the user sets image forming conditions, that is, the type of paper P (for example, basis weight, size, paper quality, etc.), paper feed tray to be used, image density, magnification, image forming mode, and the like. be able to. Further, the user can input job execution commands and operation instructions in various modes through the operation unit 14. The control unit 11 can display various messages to the user via the operation unit 14 by controlling the operation unit 14.

[Operation of Image Forming Apparatus 100]
Next, the operation of the image forming apparatus 100 in the present embodiment will be described.
FIG. 3 is a flowchart showing an image forming process executed by the image forming apparatus 100. The processing shown in this flowchart is executed in cooperation with the program stored in the control unit 11 and the storage unit 12 in accordance with a job execution command from the user.

First, the control unit 11 acquires job information transmitted from an external device via the communication unit 13 (step S1).
The job information includes various types of information related to image forming processing, such as image data of an image to be formed, mode information, and the like.
As mode information, for example, a normal mode, a duplex mode, and a gloss adjustment mode are set. The normal mode is a mode in which image formation is performed on one side of the paper P with default settings. The duplex mode is a mode in which image formation is performed on both sides of the paper P. The gloss adjustment mode is a mode for adjusting the gloss of the image formed on the paper P.

  Next, the control unit 11 determines whether or not the normal mode has been set (step S2). If the normal mode has been set (step S3: YES), the image forming unit 10 forms a toner image on the paper P. Then, a fixing process for fixing the toner image on the paper P is performed by the fixing device 20 (step S4), and this process is terminated.

On the other hand, when the normal mode is not set (step S2: NO), the control unit 11 determines whether or not the duplex mode is set (step S5).
If the duplex mode is set (step S5: YES), the control unit 11 forms a toner image on the paper P by the image forming unit 10 (step S6), and the fixing device 20 forms the toner image on the paper P. A fixing process for fixing the toner image is performed (step S7), and it is determined whether or not image formation on both sides has been completed (step S8). If image formation on both sides has been completed (step S8: YES) This process is terminated.

  On the other hand, when the double-sided image formation has not been completed (step S8: NO), the control unit 11 switches the switching gate G to convey the paper P to the circulation path R3 (step S9), and the reversing roller 47 is moved. By reversing, the paper P is conveyed to the ADU reversing path R4 (step S10), and after the paper P is returned to the image forming path R1 by the ADU reversing path R4 (step S11), the process proceeds to step S6. The subsequent processing is repeated.

If the duplex mode is not set (in the case of the gloss adjustment mode) (step S5: NO), the control unit 11 forms a toner image on the paper P by the image forming unit 10 (step S12) and stores it. The processing conditions are acquired with reference to the setting table 121 of the unit 12 (step S13).
At this time, the control unit 11 may correct the heating temperature (processing condition) set in the setting table 121 based on the measurement result of the image reading unit 30.

Next, the control unit 11 performs a fixing process for fixing the toner image on the paper P by the fixing device 20 under the acquired processing conditions (step S14).
Next, the control unit 11 determines whether or not all the gloss adjustment processes that have been set have been completed (step S15). If the gloss adjustment process has been completed (step S15: YES), the process ends.

  On the other hand, if the set gloss adjustment processing has not been completed (step S15: NO), the control unit 11 switches the switching gate G and conveys the paper P to the circulation path R3 (step S16). Then, after the sheet P is returned to the image forming path R1 by the circulation path R3 (step S17), the process proceeds to the above step S12, and the subsequent processing is repeated.

As described above, according to the present embodiment, the image forming unit 10 that forms a toner image on the paper P, and the fixing process that fixes the toner image formed on the paper P by the image forming unit 10 by heating and pressing. The image forming path R1 for conveying the sheet P to the image forming unit 10 and the fixing apparatus 20, and the image forming path R1 downstream from the fixing apparatus 20 in the sheet conveying direction. In addition, a circulation path R3 that joins the image formation path R1 and circulates the sheet P so that the image forming surface of the sheet P becomes the same surface upstream in the sheet conveyance direction, and the sheet P on which the toner image is fixed by the fixing device 20 And a control unit 11 that performs a gloss adjustment process for adjusting the gloss by heating and pressurizing by the fixing device 20 without performing image formation by the image forming unit 10 without being circulated through the circulation path R3. That.
For this reason, for example, the gloss adjustment is possible without separately providing a configuration for adjusting the gloss such as the second fixing device 20. Therefore, the gloss of the image can be controlled without increasing the size or cost of the image forming apparatus 100.

Further, according to the present embodiment, the control unit 11 varies the processing conditions including the heating temperature in the fixing process and the gloss adjustment process. For example, the control unit 11 makes the heating temperature for the gloss adjustment process higher than the heating temperature for the fixing process.
For this reason, it is possible to ensure the fixability required in the fixing process and to give the image a desired gloss in the gloss adjustment process.

Further, according to the present embodiment, the control unit 11 sets processing conditions including the heating temperature in the fixing process and the gloss adjustment process according to the type and basis weight of the paper P.
For this reason, more appropriate fixing processing and gloss adjustment processing can be executed in accordance with the type and basis weight of the paper P.

Further, according to the present embodiment, the image reading unit 30 that measures the gloss of the paper P on which the toner image is fixed by the fixing device 20 is provided, and the control unit 11 is based on the measurement result of the image reading unit 30. The processing conditions including the heating temperature in the gloss adjustment processing are corrected.
For this reason, the desired gloss can be realized more accurately.

Further, according to the present embodiment, the control unit 11 executes the gloss adjustment process when the gloss adjustment mode for adjusting the gloss is selected.
Therefore, when the gloss adjustment mode is arbitrarily selected by the user, it is possible to execute a gloss adjustment process for realizing a desired gloss.

In the above embodiment, the configuration in which the heating temperature is controlled as the processing condition in the fixing process and the gloss adjustment process has been described as an example. However, the heating pressure may be controlled as the processing condition. And it is good also as a structure which controls pressurizing force. Furthermore, the processing conditions can be configured to control the conveyance speed of the paper P.
When the pressure is controlled, it is possible to perform processing more quickly than temperature control, which is preferable from the viewpoint of productivity. Note that the user can arbitrarily set whether to switch between the heating temperature and the applied pressure.

  Further, in the above embodiment, from the viewpoint of improving accuracy, the configuration for correcting the processing condition in the gloss adjustment processing based on the measurement result of the image reading unit 30 has been described as an example. However, the image reading unit 30 is provided. Alternatively, a configuration in which correction is not performed may be employed.

  Further, in the above-described embodiment, the configuration in which the gloss adjustment process is executed when the gloss adjustment mode is selected has been described as an example. However, based on the measurement result of the image reading unit 30, a preset glossiness is set. The gloss adjustment process may be automatically executed when the value is less than.

Moreover, in the said embodiment, although the structure provided in the position which the joining point 51 and the joining point 52 left | separated was illustrated and demonstrated, it is good also as a structure which makes the joining point 51 and the joining point 52 the same position.
In this way, the standby position for the next sheet P can be set further downstream, and the productivity can be improved.

Further, the number of gloss adjustment processes to be executed for one paper P is not particularly limited, and can be set arbitrarily.
Alternatively, images may be formed on both sides of the paper P, and gloss adjustment processing may be performed on each side. In this case, since heat is applied more than on one side, it is preferable to lower the heating temperature of the gloss adjustment process as a whole.

  Further, a fan that blows air to the nip portion of the fixing device 20 may be provided, and air may be blown when the paper P passes through the fixing device 20 in the gloss adjustment processing.

The paper P applicable to the above embodiment may be a long paper that is long in the paper conveyance direction as well as a standard paper.
When the paper P is a long paper, the paper P is image-formed by, for example, a paper feeding device (not shown) connected to the image forming apparatus 100 or a manual feed tray provided in the image forming apparatus 100. It can be sent out to the route R1.

  In the above-described embodiment, an example in which a non-volatile memory, a hard disk, or the like is used as a computer-readable medium for the program according to the present invention is disclosed, but the present invention is not limited to this example. As another computer-readable medium, a portable recording medium such as a CD-ROM can be applied. A carrier wave is also applied as a medium for providing program data according to the present invention via a communication line.

  In addition, the detailed configuration and detailed operation of the image forming apparatus can be changed as appropriate without departing from the spirit of the present invention.

100 Image forming apparatus SC Document reading apparatus 10 Image forming units 10Y, 10M, 10C, 10K Image forming units 1Y, 1M, 1C, 1K Photosensitive drums 2Y, 2M, 2C, 2K Charging units 3Y, 3M, 3C, 3K Optical writing 4Y, 4M, 4C, 4K Developing devices 5Y, 5M, 5C, 5K Drum cleaner 6 Intermediate transfer belt 7Y, 7M, 7C, 7K, 7W Primary transfer roller 8 Secondary transfer roller 20 Fixing device (fixing unit)
30 Image reading unit (gloss measuring unit)
40 Paper transport unit 41 Paper feed tray 42 Paper feed unit 43 Intermediate transport roller 44 Loop roller 45 Registration roller 46 Paper discharge tray 47 Reverse roller 48 Intermediate transport roller 51 Merge point 52 Merge point R1 Image formation route R2 Paper discharge route R3 Circulation route R4 Reverse path G Switching gate 11 Control unit 12 Storage unit 121 Setting table 13 Communication unit 14 Operation unit P Paper

Claims (8)

An image forming unit for forming a toner image on paper;
A fixing unit that performs a fixing process of fixing the toner image formed on the paper by the image forming unit by heating and pressing; and
An image forming path for conveying paper to the image forming unit and the fixing unit;
Branch from the image forming path downstream of the fixing unit in the sheet conveying direction, and join the image forming path so that the image forming surface of the sheet becomes the same surface upstream of the image forming unit in the sheet conveying direction. A circulation path for circulating
Gloss adjustment processing is performed in which the sheet on which the toner image is fixed by the fixing unit is circulated through the circulation path, and the gloss is adjusted by heating and pressing by the fixing unit without image formation by the image forming unit. A control unit;
An image forming apparatus comprising:   The image forming apparatus according to claim 1, wherein the control unit varies processing conditions including a heating temperature and a pressing force in the fixing process and the gloss adjustment process.   The image forming apparatus according to claim 2, wherein the control unit sets a heating temperature of the gloss adjustment process higher than a heating temperature of the fixing process.   4. The control unit according to claim 1, wherein the control unit sets processing conditions including a heating temperature and a pressurizing force in the fixing process and the gloss adjustment process according to a paper type and a basis weight. The image forming apparatus described in the item. A gloss measuring unit for measuring the gloss of the paper on which the toner image is fixed by the fixing unit;
The said control part correct | amends the process conditions containing the heating temperature and pressurization force in the said gloss adjustment process based on the measurement result of the said glossiness measurement part, It is any one of Claim 1 to 4 characterized by the above-mentioned. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit executes the gloss adjustment processing when a gloss adjustment mode for adjusting gloss is selected. An image forming unit that forms a toner image on a sheet, a fixing unit that performs fixing processing for fixing the toner image formed on the sheet by heating and pressurizing by the image forming unit, and the image forming unit and the fixing unit Branching from the image forming path transported in the paper and the image forming path downstream in the paper transport direction from the fixing unit, and the image forming surface of the paper is the same surface upstream in the paper transport direction from the image forming unit An image forming method in an image forming apparatus, comprising: a circulation path that joins an image forming path to circulate paper; and a control unit,
The control unit circulates the paper on which the toner image is fixed by the fixing unit through the circulation path, and adjusts the gloss by heating and pressing the fixing unit without forming an image by the image forming unit. An image forming method comprising a step of executing an adjustment process. An image forming unit that forms a toner image on a sheet, a fixing unit that performs fixing processing for fixing the toner image formed on the sheet by heating and pressurizing by the image forming unit, and the image forming unit and the fixing unit Branching from the image forming path transported in the paper and the image forming path downstream in the paper transport direction from the fixing unit, and the image forming surface of the paper is the same surface upstream in the paper transport direction from the image forming unit A circulation path for joining the image formation path and circulating the paper, and a computer of the image forming apparatus,
Gloss adjustment processing is performed in which the sheet on which the toner image is fixed by the fixing unit is circulated through the circulation path, and the gloss is adjusted by heating and pressing by the fixing unit without image formation by the image forming unit. A program for functioning as a control unit.

Images