JP5073586B2 - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that is able to output a satisfactory image by preventing fixing failure of a toner image on a second printing side of paper due to high temperature offset of a toner image in double-sided printing of the image forming apparatus with an option device attached thereto, and that is able to suppress thermal damage to a composing part in the apparatus. <P>SOLUTION: The image forming apparatus 100 includes a fixing unit 7 for fixing an unfixed toner image, transferred to paper, at a predetermined temperature, is capable of double-sided printing, and is configured so that the option device 40 is attached to the body of the apparatus. The image forming apparatus includes a determining means 304 for determining whether the option device 40 has been attached or not; and a control means 305 for altering the fixing temperature of the fixing unit 7 for double-sided printing based on the result of the determination made by the determining means 304. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus configured to be capable of duplex printing and to be equipped with an optional device on the apparatus main body.

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a copying machine, a printer, and a facsimile is used as a fixing device used for fixing an unfixed toner image transferred onto a sheet. In general, a toner image is melted and fixed by passing through a nip portion between them. In recent years, an image forming apparatus configured as described above is known as a system configured by adding an optional apparatus such as a post-processing apparatus.

  When an optional device is added to the image forming apparatus and configured as a system, the power consumption of the entire system increases. This affects the power supply to the fixing device that consumes a large amount of power in the image forming apparatus, and there is a problem that stable fixing processing by the fixing device may not be ensured.

  Therefore, in order to solve the above problem, as a conventional technique, for example, in an image forming apparatus in which an optional device can be mounted, a fixing device that fixes an unfixed toner image transferred to a sheet, and power supplied to the fixing device And a control circuit that determines whether or not the optional device is installed. The control circuit determines whether or not the optional device is installed, and based on the determination result, the power supplied to the fixing device and the fixing when the copy is stopped A device that sets the temperature of the apparatus has been proposed (see Patent Document 1).

As another technique, in an image forming apparatus that includes an apparatus main body provided with a fixing device and an optional apparatus, and supplies power to the apparatus main body and the optional apparatus from a common power supply unit, a temperature sensor that measures the temperature of the apparatus main body Proposed to diagnose the power shortage level of the image forming device based on the combination of the temperature sensor that measures the temperature of the optional device and the temperature measurement result of the temperature sensor when the power is turned on or when the print start instruction is received (See Patent Document 2).
JP 2005-17737 A JP 2007-52318 A

  However, in a conventional image forming apparatus equipped with an optional device, when duplex printing is performed with the optional device mounted on the paper discharge side of the apparatus main body, printing on the first printing surface (front surface) of the paper is completed. When the reverse conveyance process is performed to reverse the paper and return it to the apparatus main body again, the paper discharged from the apparatus main body is once introduced into the optional device. As compared with the case of performing the above, the temperature in the apparatus main body increases. As a result, the sheet becomes equal to or higher than the set temperature, causing a problem that a high-temperature offset occurs and the toner image on the second printing surface becomes poorly fixed. In addition, there is a problem in that the component parts inside the apparatus main body are damaged by heat, thereby shortening the service life of the component parts.

  The present invention has been made in view of the above-described conventional problems, and the toner image on the second printing surface of the paper due to the high-temperature offset of the toner image at the time of duplex printing of the image forming apparatus equipped with the optional device. An object of the present invention is to provide an image forming apparatus capable of preventing occurrence of fixing failure and enabling good image output and suppressing damage caused by heat of components in the apparatus.

  The configuration of the image forming apparatus according to the present invention for solving the above problems is as follows.

The present invention provides an image forming apparatus that includes a fixing device that fixes an unfixed toner image transferred to a recording medium at a predetermined temperature, is capable of duplex printing, and is configured such that an optional device can be attached to the apparatus body. A determination unit that determines whether or not the optional device is mounted, and when the determination unit determines that the optional device is mounted, both sides are more than the case where it is determined that the optional device is not mounted. Control means for lowering the fixing temperature of the fixing device with respect to the second printing surface during printing, and the optional device is mounted on the device main body and discharged from the device main body in the reverse conveyance process during double-sided printing. The recording medium is arranged at a position where the recording medium is introduced .

According to the present invention, when the control unit determines that the optional device is installed by the control unit, the fixing temperature of the fixing device with respect to the second printing surface during duplex printing is set to the first temperature during single-sided printing. It is preferable that the temperature is lower than the fixing temperature of the fixing device for one printing surface.
In the present invention, the first printing surface is a printing surface on which printing is first performed during duplex printing of a recording medium, and the second printing surface is a printing surface on the back of the first printing surface on which printing is performed later.

  In the present invention, it is preferable that the fixing temperature is changed according to the thickness of the recording medium by the control means.

  In the present invention, it is preferable that the optional apparatus performs the reverse conveyance processing of the recording medium in the apparatus.

  In the present invention, it is preferable that the optional device is a post-processing device that performs post-processing on a recording medium.

According to the present invention, an image forming apparatus that includes a fixing device that fixes an unfixed toner image transferred to a recording medium at a predetermined temperature, is capable of duplex printing, and can be equipped with an optional device in the apparatus main body. The determination means for determining whether or not the option device is mounted, and when the determination device determines that the option device is mounted than when the option device is determined not to be mounted Control means for lowering the fixing temperature of the fixing device with respect to the second printing surface during double-sided printing, and with the optional device mounted on the device main body, in the reverse conveyance processing during double-sided printing, from the device main body by discharged recording medium is placed in a position to be introduced, when performing duplex printing while wearing the option device, the constant by the control means By changing the fixing temperature of the device, the temperature control of the optimum fixing temperature for the recording medium is performed, the high-temperature offset of the toner image is prevented, and the fixing failure of the toner image is prevented. Damage to the component due to heat can be suppressed.

  According to the invention, the fixing temperature of the fixing device with respect to the second printing surface (back surface) at the time of duplex printing is determined by the control unit when the determination unit determines that the optional device is mounted. By lowering the fixing temperature of the fixing device for the first printing surface (front surface) during single-sided printing, the fixing temperature for the back surface (second printing surface) during double-sided printing can be lowered according to the optional mounting state. Therefore, the fixing temperature for the recording medium can be optimized and the occurrence of fixing failure of the toner image can be prevented.

  According to the invention, the fixing temperature is changed according to the thickness of the recording medium by the control means, so that the fixing temperature for the recording medium can be optimized.

  Also, according to the present invention, the effect of heat on the apparatus main body due to the paper after the first printing can be reduced by performing the reverse conveyance process of the recording medium in the apparatus by the optional apparatus.

  According to the present invention, the optional device is a post-processing device that performs post-processing on the recording medium, so that the fixing temperature for the recording medium can be optimized even when the post-processing device is mounted on the main body of the apparatus. As a result, it is possible to prevent occurrence of poor fixing of the toner image.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention, and FIG. 2 is an explanatory diagram showing an electrical configuration of a control unit that controls a fixing unit of the image forming apparatus.

  As shown in FIGS. 1 and 2, the present embodiment includes a fixing unit (fixing device) 7 that fixes an unfixed toner image transferred onto a sheet (recording medium) at a predetermined temperature, and can perform duplex printing. In the image forming apparatus 100 that is configured so that an optional device can be mounted on the apparatus main body, the configuration of the control unit 30 that controls the operation of the image forming apparatus 100 includes a determination unit 304 that determines whether the optional device 40 is mounted. And a control unit 305 for changing the fixing temperature of the fixing unit 7 at the time of double-sided printing based on the determination result by the determining unit 304. When double-sided printing is performed with the optional device 40 mounted, the fixing is performed by the control unit 305. The fixing temperature of the unit 7 is changed.

First, the overall configuration of the image forming apparatus 100 according to the present embodiment will be described.
As shown in FIG. 1, the image forming apparatus 100 forms multicolor and single color images on a predetermined sheet (for example, recording sheet) in accordance with image data transmitted from the outside. 110 and an automatic document processing apparatus 120.

  The apparatus main body 110 includes an exposure unit 1, a developing device 2, a photosensitive drum 3, a cleaner unit 4, a charger 5, a transfer unit 6, a fixing unit 7, a paper feed cassette 81, a paper discharge tray 91, and the like. ing.

  On the upper side of the image reading unit 90 provided on the upper part of the apparatus main body 110, there is provided a document placing table 92 made of transparent glass on which a document is placed. Above the document placing table 92, an automatic document processing device 120 is provided. Is attached.

The automatic document processing device 120 automatically conveys the document on the document placing table 92.
Further, the automatic document processing device 120 is configured to be rotatable in the direction of arrow M, and the document can be placed manually by opening the document table 92.

Image data handled in the image forming apparatus 100 corresponds to a color image using each color of black (K), cyan (C), magenta (M), and yellow (Y).
Accordingly, four developing devices 2, photosensitive drums 3, chargers 5, and cleaner units 4 are provided to form four types of latent images corresponding to the respective colors. Black, cyan, magenta, and yellow are respectively provided. These are set to form four image stations.

  The exposure unit 1 exposes the charged photosensitive drum 3 in accordance with image data input from the outside or image data obtained by reading from a document, thereby generating an electrostatic latent image corresponding to the image data on the photosensitive body. This is an image writing device formed on the surface of the drum 3, and is configured as an LSU (laser scanning unit) provided with a laser emitting portion, a reflection mirror, and the like. The exposure unit 1 is also provided with a polygon mirror that scans the laser beam and optical elements such as a lens and a mirror for guiding the laser beam reflected by the polygon mirror to the photosensitive drum 3.

  Further, as the exposure unit 1, in addition to the above-described configuration, for example, a method using an EL or LED writing head in which light emitting elements are arranged in an array can be employed.

  The exposure unit 1 thus configured forms an electrostatic latent image on the surface of the photosensitive drum 3 by exposing the charged photosensitive drum 3 according to the input image data. It has the function to do.

  The developing device 2 visualizes the electrostatic latent images formed on the respective photosensitive drums 3 with toners of four colors (Y, M, C, K).

  The photosensitive drum 3 has a cylindrical shape, is disposed above the exposure unit 1, the surface thereof is cleaned by the cleaner unit 4, and the cleaned surface is uniformly charged by the charger 5.

  The cleaner unit 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  The charger 5 is a charging means for uniformly charging the surface of the photosensitive drum 3 to a predetermined potential. In addition to a charger type as shown in FIG. 1, a contact type roller type or brush type charger is used. It may be used.

  The transfer unit 6 disposed above the photosensitive drum 3 includes an intermediate transfer belt 61, an intermediate transfer belt driving roller 62, an intermediate transfer belt driven roller 63, an intermediate transfer roller 64, and an intermediate transfer belt cleaning unit 65. Yes. Four intermediate transfer rollers 64 are provided corresponding to each color of Y, M, C, and K.

  The intermediate transfer belt driving roller 62, the intermediate transfer belt driven roller 63, and the intermediate transfer roller 64 are configured to stretch and drive the intermediate transfer belt 61.

  The intermediate transfer belt 61 is formed in an endless shape using a film having a thickness of about 100 μm to 150 μm, and is provided so as to contact each photosensitive drum 3. A function of forming a color toner image (multicolor toner image) on the intermediate transfer belt 61 by sequentially superimposing and transferring the toner images of the respective colors formed on the photosensitive drum 3 onto the intermediate transfer belt 61. have.

  Transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 61 is performed by an intermediate transfer roller 64 that is in contact with the back side of the intermediate transfer belt 61.

  Each intermediate transfer roller 64 applies a transfer bias for transferring the toner image on the photosensitive drum 3 onto the intermediate transfer belt 61 with respect to the intermediate transfer belt 61. Specifically, a high voltage transfer bias (a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 64 in order to transfer the toner image.

  The intermediate transfer roller 64 is a roller whose base is a metal (for example, stainless steel) shaft having a diameter of 8 to 10 mm and whose surface is covered with a conductive elastic material (for example, EPDM, urethane foam, or the like). With this conductive elastic material, a high voltage can be uniformly applied to the intermediate transfer belt 61. In this embodiment, the roller-shaped intermediate transfer roller 64 is used as the transfer electrode, but a brush or the like can also be used.

  As described above, the toner images visualized according to the hues on the photosensitive drums 3 are stacked on the intermediate transfer belt 61. The stacked toner images as image information are conveyed together with the intermediate transfer belt 61 and moved to a contact position (secondary transfer position, predetermined position) between the conveyed paper and the intermediate transfer belt 61, and this secondary position. The image is transferred onto the paper by the transfer roller 10 arranged on the paper.

  At this time, the intermediate transfer belt 61 and the transfer roller 10 are pressed against each other at a predetermined nip, and a secondary transfer bias is applied to the transfer roller 10 to transfer the toner image onto the sheet. The secondary transfer bias is a high voltage having a polarity (+) opposite to the charging polarity (−) of the toner.

  Further, in order to constantly obtain the predetermined nip, the transfer roller 10 that is pressed against the intermediate transfer belt 61 at the secondary transfer position or the intermediate transfer belt drive roller that is pressed against the back side of the intermediate transfer belt 61 at the secondary transfer position. Any one of 62 is made of a hard material (metal or the like), and the other is made of a soft material such as an elastic roller (elastic rubber roller or foaming resin roller or the like).

  In the transfer process described above, the toner adhering to the intermediate transfer belt 61 by coming into contact with the photosensitive drum 3 or the toner remaining on the intermediate transfer belt 61 without being transferred onto the paper by the transfer roller 10 is used in the next process. The intermediate transfer belt cleaning unit 65 is configured to remove and collect the toner image to cause a toner color mixture.

  The intermediate transfer belt cleaning unit 65 is provided on the downstream side of the transfer roller 10 and upstream of the photosensitive drum 3 in the intermediate transfer belt conveyance direction on the path along which the intermediate transfer belt 61 is conveyed.

  The intermediate transfer belt cleaning unit 65 includes a cleaning blade 65 a as a cleaning member that contacts the intermediate transfer belt 61 and cleans the surface of the intermediate transfer belt 61. The intermediate transfer belt 61 in contact with the cleaning blade 65a is supported by an intermediate transfer belt driven roller 63 from the back side.

The paper feed cassette 81 is a tray for storing sheets used for image formation, and is provided below the exposure unit 1 of the apparatus main body 110. A manual paper feed cassette 82 capable of supplying paper from the outside is provided on the outer side of the apparatus main body 110.
A plurality of sheets used for image formation can be stacked on the manual sheet feeding cassette 82. Above the apparatus main body 110, a paper discharge tray 91 for collecting printed sheets face down is provided.

  A toner cartridge 8 for replenishing toner corresponding to each developing device 2 corresponding to each color is disposed below the paper discharge tray 91.

  Further, the apparatus main body 110 has a substantially vertical sheet conveyance path S for sending the sheets of the sheet feeding cassette 81 and the manual sheet feeding cassette 82 to the sheet discharge tray 91 via the transfer roller 10 and the fixing unit 7. Is provided. In the vicinity of the sheet conveyance path S from the sheet feeding cassette 81 to the manual sheet feeding cassette 82 to the sheet discharge tray 91, pickup rollers 11a and 11b, a plurality of conveyance rollers 12a to 12d, a registration roller 13, a transfer roller 10, and a fixing roller. Unit 7 etc. are arranged.

The transport rollers 12 a to 12 d are small rollers for promoting and assisting the transport of paper, and are provided along the paper transport path S.
The pickup roller 11 a is provided near the end of the paper feed cassette 81, picks up paper one by one from the paper feed cassette 81, and supplies it to the paper transport path S.
The pickup roller 11 b is provided near the end of the manual paper feed cassette 82, picks up paper one by one from the manual paper feed cassette 82, and supplies it to the paper transport path S.

  The registration roller 13 temporarily holds the paper conveyed through the paper conveyance path S. The sheet has a function of conveying the sheet to the transfer roller 10 at the timing when the leading edge of the toner image on the photosensitive drum 3 is aligned with the leading edge of the sheet. That is, the registration roller 13 aligns the toner image on the intermediate transfer belt 61 to a predetermined position on the conveyed paper.

  The fixing unit 7 includes a pair of a heat roller 71 and a pressure roller 72 as the fixing roller 70, and the heat roller 71 and the pressure roller 72 are rotated and conveyed with a sheet interposed therebetween.

  The heat roller 71 and the pressure roller 72 are disposed to face each other, and a fixing nip portion is formed at a pressure contact portion between the heat roller 71 and the pressure roller 72.

  The temperature of the heat roller 71 is controlled by a control unit (not shown) so as to reach a predetermined fixing temperature. The controller controls the temperature of the heat roller 71 based on a detection signal from a temperature detector (non-contact type thermistor) (not shown) that detects the temperature of the heat roller 71 provided around the heat roller 71. It controls so that it may become the range of 200 degreeC.

  Further, the heat roller 71 has a function of fusing, mixing, and pressing the multicolor toner image transferred to the paper and thermally fixing the paper with the pressure roller 72 by thermally pressing the toner onto the paper. ing. As shown in FIG. 1, the heat roller 71 is provided with an external fixing belt 73 for fixing the heat roller 71 from the outside.

  On the other hand, similarly to the heat roller 71, the pressure roller 72 is also configured by providing an elastic layer on the peripheral surface of a cylindrical metal core. And it contacts with the heat roller 71 with a predetermined pressure.

Next, a paper conveyance path in the image forming apparatus 100 will be described.
As shown in FIG. 1, the image forming apparatus 100 is provided with a paper feed cassette 81 that stores paper in advance and a manual paper feed cassette 82. In order to feed paper from these paper feed cassettes 81 and 82, pickup rollers 11a and 11b are arranged, respectively, so as to guide the paper one by one to the paper transport path S.

  The paper transported from each of the paper feed cassettes 81 and 82 is transported to the registration roller 13 by the transport roller 12a in the paper transport path S, and transferred at a timing when the front end of the paper and the front end of the image information on the intermediate transfer belt 61 are aligned. It is conveyed to the roller 10 and image information is written on the paper. Thereafter, the sheet passes through the fixing unit 7 so that the unfixed toner on the sheet is melted and fixed by heat, and is then discharged onto the sheet discharge tray 91 via the transport roller 12b.

The above-mentioned paper conveyance path is for a single-sided printing request for paper.
On the other hand, when double-sided printing is requested, when single-sided printing, that is, printing on the paper surface (first printing surface) is completed and the trailing edge of the paper that has passed through the fixing unit 7 is gripped by the final transport roller 12b, The paper is guided to the transport rollers 12c and 12d by the reverse rotation of the transport roller 12b. Thereafter, the paper is printed on the back surface (second printing surface) of the paper through the registration roller 13 and then discharged to the paper discharge tray 91.

  Next, the fixing temperature control by the fixing unit 7 which is characteristic of the present embodiment will be described in detail with reference to the drawings.

  As shown in FIG. 2, the control unit 30 forms an image in the image forming unit 20 including the exposure unit 1 and the developing device 2, a sheet transport process by the transport roller 12 in the transport unit 50, a post-process by the option device 40, and the like. A CPU (Central Processing Unit) 301 that controls each unit uses temporary storage means such as a RAM (Random Access Memory) 303 in accordance with a program stored in advance in a ROM (Read Only Memory) 302. Execute each process.

  Further, the control unit 30 includes a determination unit 304 that determines whether or not the optional device is mounted, and a control unit 305 that changes the fixing temperature of the fixing unit 7 during duplex printing based on the determination result by the determination unit 304. In addition to the control of the fixing temperature in the normal fixing unit 7, the fixing temperature of the fixing unit 7 at the time of duplex printing is changed based on the determination result by the determining means 304.

  As shown in FIG. 2, the fixing unit 7 controls the temperature of the heat roller 71 by the control unit 30. The heat roller 71 provided in the fixing unit 7 includes a main heater 711a and a sub heater 711b. The main heater 711 a has a heating element 712 a having a width that is substantially the same as the width of a small-size sheet used in the image forming apparatus 100. The sub-heater 711 b is provided with a heating element 712 b having a width substantially the same as the width of a large-size sheet used in the image forming apparatus 100. On the outer periphery of the heat roller 71, temperature sensors 713a and 713b are arranged in a portion where the main heater 711a is arranged and a portion where the sub heater 711b is arranged.

  The temperature sensors 713a and 713b are installed at positions facing each other within the width of the heating elements 712a and 712b of the main heater 711a and the sub heater 711b, respectively, and temperature information detected by the temperature sensors 713a and 713b is respectively input circuit 714a , 714b to be taken into the control unit 30.

  The main heater 711a and the sub heater 711b are connected to the control unit 30 via drivers 715a and 715b, respectively.

  The CPU 301 is configured to control energization of each heater via the drivers 715a and 715b based on the heat roller surface temperature detected by the temperature sensors 713a and 713b. The CPU 301 is configured to control the operation of the option device 40 in addition to the operation control of each part of the apparatus main body.

Next, operation control during double-sided printing in the image forming apparatus 100 of the present embodiment will be described in detail with reference to the drawings.
FIG. 3A is an explanatory diagram illustrating a state in which the first printing of the paper is completed at the time of duplex printing when the optional device is installed in the image forming apparatus of the present embodiment, and FIG. 3B is a duplex printing of the image forming apparatus. FIG. 4C is an explanatory view showing a reverse state for the second printing of the paper at the time, FIG. 4C is an explanatory view showing a transport state for the second printing of the paper at the time of duplex printing of the image forming apparatus, FIG. FIG. 7 is an explanatory diagram showing a state where the first printing of the paper is completed at the time of duplex printing when the optional device is not attached to the image forming apparatus of the present embodiment, and FIG. FIG. 4C is an explanatory diagram illustrating a reversed state for two printing, and FIG. 8C is an explanatory diagram illustrating a conveyance state for second printing of a sheet during duplex printing of the image forming apparatus.

  When double-sided printing is performed on a sheet with the post-processing device installed as the optional device 40 in the image forming apparatus 100, as shown in FIGS. 3A and 3B, the sheet P after the first printing is reversed and conveyed. Since the operation is executed in the option device 40 (see section A1), the temperature in the option device 40 rises due to the paper P heated by the fixing unit 7, and a temperature equal to or higher than the set temperature is given to the paper P. It will be in a state to end up.

  That is, when the optional device 40 is mounted on the image forming apparatus 100 shown in FIGS. 3A to 3C, when the paper P performs the reverse conveyance operation, the images shown in FIGS. 4A to 4C are displayed. Compared to the case where the optional device 40 is not attached to the forming apparatus 100, the sheet P is in a state in which it is less likely to come into contact with the outside air (see the A1 and A2 parts). Accordingly, the heated paper P in the fixing unit 7 is difficult to be cooled, and when the number of printed sheets by double-sided printing is increased, the temperature in the option device 40 rises with time and the paper P is more difficult to be cooled (B1 portion). (See B2).

  The temperature of the paper P during the reverse conveyance is about 5 to 10 ° C. higher when the optional device 40 is installed than when the optional device 40 is installed and when the optional device 40 is not installed. In this state, as shown in FIG. 3C, when the paper P is transported into the apparatus main body and the second printing is performed, the temperature of the paper P during the second printing of the paper P, that is, the printing on the back surface. Becomes about 3-5 ° C. high.

  At this time, since the temperature inside the apparatus main body is about 5 ° C. higher, the set temperature of the fixing temperature of the paper P at the time of the second printing can be set lower by about 5 ° C. than the temperature in the normal state. Become.

Here, management of the fixing temperature of the fixing unit 7 in the image forming apparatus 100 of the present embodiment will be described.
FIG. 5 is a table showing an example of a management table for managing the target set temperature of the fixing temperature in the fixing unit in the image forming apparatus of this embodiment.

  The fixing unit 7 is configured to change the fixing temperature at the time of duplex printing by the control unit 305 based on the determination result by the determination unit 304 that determines whether or not the optional device 40 is installed.

  As shown in FIGS. 5A and 5B, the fixing temperature of the fixing unit 7 set by the control unit 305 is set as follows: whether or not the optional device 40 is installed in the image forming apparatus 100, the type of paper, and the printing conditions (single side). In accordance with printing or duplex printing, the target set temperature of the fixing temperature of the fixing unit 7 and the sheet conveyance speed are set based on a preset management table.

Here, as the definition of the type of paper, thick paper: about 200 g / m ² (basis weight) and standard paper: 64 g / m ² (basis weight). Note that the target set temperature of the fixing temperature of the fixing unit 7 may be changed according to conditions such as thin paper, postcards, and envelopes.

  Specifically, when the option device 40 is not attached to the image forming apparatus 100, the management table is a first management table 305a as a fixing temperature target of the fixing unit 7 as shown in FIG. The set temperature and paper transport speed are 180 ° C. and 200 mm / s for A4 plain paper, 185 ° C. and 200 mm / s for A3 plain paper, 200 ° C. and 100 mm / s for A4 thick paper, and 205 ° C. and 100 mm / s for A3 thick paper. It is set to be. This first management table 305a is mainly used during single-sided printing and first printing (front-side printing) during double-sided printing.

  Specifically, A3 plain paper is 185 ° C., which is 5 ° C. higher than A4 plain paper because it is easy to cool because it has a longer paper length than A4 plain paper. Since A4 thick paper is harder to transmit temperature than A4 plain paper, the target set temperature is increased to 200 ° C. and the paper conveyance speed is decreased to 100 mm / s. Since the A3 thick paper has a longer paper length than the A4 thick paper and is easy to cool, the target set temperature is set to 205 ° C., which is 5 ° C. higher than the A4 thick paper, and the paper conveyance speed is set to 100 mm / s as in the A4 thick paper.

  On the other hand, when the option device 40 is installed in the image forming apparatus 100, as shown in FIG. 5B, the second management table 305b is 175 ° C. for A4 plain paper, 200 mm / s, and for A3 plain paper. It is set to 175 ° C. and 200 mm / s, 190 ° C. and 100 mm / s for A4 cardboard, and 190 ° C. and 100 mm / s for A3 cardboard. The second management table 305b is mainly used at the time of second printing (back surface printing) at the time of duplex printing.

  Specifically, A3 plain paper is 175 ° C., similarly to A4 plain paper, because it is difficult to cool compared to the case where the optional device 40 is not installed. Since A4 thick paper is harder to cool than A4 plain paper, it is 190 ° C., which is lower than the target set temperature when the optional device 40 is not mounted, and the paper conveyance speed is slowed to 100 mm / s. Since the A3 thick paper is difficult to cool compared to the case where the optional device 40 is not installed, the target set temperature is set to 190 ° C. and the paper transport speed is set to 100 mm / s similarly to the A4 thick paper.

  Based on the first management table 305a and the second management table 305b set as described above, the control unit 30 determines whether or not the optional device 40 of the image forming apparatus 100 is mounted and the type of paper used. 7 is controlled to change the target set temperature of the fixing temperature.

Next, temperature control of the fixing unit 7 in the image forming apparatus 100 of the present embodiment will be described with reference to a flowchart.
FIG. 6 is a flowchart illustrating an example of temperature control of the fixing unit of the image forming apparatus according to the present exemplary embodiment.

  As shown in FIG. 6, when the operation of the image forming apparatus 100 of the present embodiment is started and a print request is made (step S1), either one-sided printing or two-sided printing is set as a printing condition. (Step S2), it is determined whether the paper to be printed is plain paper or thick paper (Step S3). These printing conditions and paper types are usually input by an operator using the operation panel 101 (see FIG. 2) of the image forming apparatus 100.

  Then, the determination unit 304 determines whether or not the optional device 40 is mounted (step S4). If it is determined in step S4 that the optional device 40 is mounted, it is determined whether or not to perform printing on the first printing surface (front surface) side as a surface to be printed (step S5).

  If it is determined in step S5 that the printing process is for the first printing surface, the control unit 305 determines the fixing temperature target of the fixing unit 7 based on the first management table 305a based on the determination results in steps S2 to S4. The set temperature is determined (step S6), and the printing process is executed (step S8).

  If it is determined in step S5 that the printing process is not for the first printing surface, the control unit 305 determines the fixing temperature target of the fixing unit 7 based on the second management table 305b based on the determination results in steps S2 to S4. The set temperature is determined (step S7), and the printing process is executed (step S8). This print processing step is executed at the time of double-sided printing in which second printing described later is performed.

  On the other hand, if it is determined in step S4 that the optional device 40 is not installed, the control unit 305 determines the fixing temperature of the fixing unit 7 based on the first management table 305a based on the determination results in steps S2 to S3. A target set temperature is determined (step S6), and a printing process is executed (step S8).

  Next, it is determined whether or not there is a printing process for the second printing surface (back surface) (step S9). If it is determined in step S9 that there is a printing process for the second printing surface, the process returns to step S5, and the fixing is performed again by the control unit 305 using the second management table 305b based on the determination results in steps S2 to S5. A target set temperature for the fixing temperature of the second printing surface by the unit 7 is determined (step S7), and a printing process is performed (step S8).

  On the other hand, if it is determined in step 9 that it is not necessary to print the second printing surface, the printing process ends.

  As described above, according to the present embodiment, the control unit 30 that controls the operation of the image forming apparatus 100 includes the determination unit 304 that determines whether or not the option device 40 is mounted and the determination unit 304. And a control unit 305 that changes the fixing temperature of the fixing unit 7 during duplex printing based on the determination result. The control unit 305 sets the fixing temperature of the fixing unit 7 using the first management table 305a and the second management table 305b. As a result, when performing double-sided printing with the optional device 40 mounted, the fixing temperature for the second printing surface is set lower than that for the first printing surface, and optimal fixing to the paper P is performed. Since temperature control of the temperature can be performed, high temperature offset of the toner image is prevented when printing on the second printing surface, and the fixing failure of the toner image is prevented. It can be.

  In addition, according to the present embodiment, the control unit 305 sets the target set temperature of the fixing temperature of the fixing unit 7 lower than the normal set temperature when the optional device 40 is mounted, so that the inside of the device main body or the optional device 40 is set. Can be prevented from being overheated, so that damage to the components in the apparatus due to heat can be suppressed.

  In the present embodiment, the fixing temperature of the fixing unit 7 is set and changed by the control unit 305 using the management table of the first management table 305a and the second management table 305b. However, the management table is an example. And it is not limited to this value.

  Further, the setting of the fixing temperature of the fixing unit 7 by the control unit 305 is not limited to the setting based on the above-described management table. For example, on the operation panel 101, the presence or absence of an optional device, the thickness of the sheet Alternatively, an input means for inputting the paper size and the like may be provided, and the fixing temperature may be selectively set according to the input conditions.

  In this embodiment, the determination unit 304 and the control unit 305 are configured as a part of the control unit 30 that controls the image forming apparatus 100 as a whole, but the control unit that sets the fixing temperature of the fixing unit 7. The determination unit 304 and the control unit 305 may be provided separately from the control unit 30.

  The preferred embodiments of the present invention have been described above. However, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope shown in the claims. Embodiments obtained by appropriately combining the disclosed technical means are also included in the technical scope of the present invention.

  For example, in the above-described embodiment, the present invention is applied to a color image forming apparatus (multifunction machine, printer, etc.), but the present invention can also be applied to a monochrome image forming apparatus.

1 is an explanatory diagram showing an overall configuration of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a block diagram illustrating an electrical configuration of a control unit that controls a fixing unit of the image forming apparatus. (A) is an explanatory view showing a state in which the first printing of the paper at the time of double-sided printing when the optional device is mounted on the image forming apparatus, and (b) is the first sheet of paper at the time of double-sided printing of the image forming apparatus. FIG. 4C is an explanatory diagram illustrating a reversed state for two printing, and FIG. 8C is an explanatory diagram illustrating a conveyance state for the second printing of the paper during duplex printing of the image forming apparatus. (A) is an explanatory view showing a state in which the first printing of the paper at the time of duplex printing when the optional device is not attached to the image forming apparatus, and (b) is the first sheet of paper at the time of duplex printing of the image forming apparatus. FIG. 4C is an explanatory diagram illustrating a reversed state for two printing, and FIG. 8C is an explanatory diagram illustrating a conveyance state for the second printing of the paper during duplex printing of the image forming apparatus. 6 is a table showing an example of a management table for managing a target set temperature of a fixing temperature in a fixing unit in the image forming apparatus. 3 is a flowchart illustrating an example of temperature control of a fixing unit of the image forming apparatus.

Explanation of symbols

7 Fixing unit (fixing device)
DESCRIPTION OF SYMBOLS 30 Control part 40 Option apparatus 70 Fixing roller 71 Heat roller 100 Image forming apparatus 101 Operation panel 110 Apparatus main body 304 Judgment means 305 Control means 305a 1st management table (control means)
305b Second management table (control means)
P paper

Claims (5)

An image forming apparatus including a fixing device that fixes an unfixed toner image transferred to a recording medium at a predetermined temperature, capable of duplex printing, and configured to be equipped with an optional device in the apparatus body.
Determining means for determining whether or not the optional device is mounted;
When it is determined by the determining means that the optional device is mounted, the fixing temperature of the fixing device with respect to the second printing surface during duplex printing is set more than when it is determined that the optional device is not mounted. And a control means for lowering ,
The image forming apparatus , wherein the optional device is mounted on the apparatus main body, and is disposed at a position where a recording medium discharged from the apparatus main body is introduced in a reverse conveyance process during duplex printing .   The control unit determines the fixing temperature of the fixing device with respect to the second printing surface during double-sided printing and the fixing device with respect to the first printing surface during single-sided printing when the determining unit determines that the optional device is mounted. The image forming apparatus according to claim 1, wherein the fixing temperature is lower than the fixing temperature of the image forming apparatus.   The image forming apparatus according to claim 1, wherein the control unit changes a fixing temperature according to a thickness of the recording medium.   The image forming apparatus according to claim 1, wherein the optional device performs a reverse conveyance process of a recording medium in the device.   The image forming apparatus according to claim 1, wherein the optional device is a post-processing device that performs post-processing on a recording medium.

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