JP2018165736A - Image forming apparatus and control program for image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of appropriately suppressing waving of an envelope and a control program of the image forming apparatus.SOLUTION: An image forming apparatus 1 has a fixing device 30 for fixing toner onto an envelope prepared by pasting a recording medium. The image forming apparatus 1 detects a pasting position of the envelope before the toner is fixed onto the envelope by the fixing device 30, and switches a fixing condition as a condition when the toner is fixed onto the envelope by the fixing device 30 in accordance with the detected pasting position.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus and a control program for the image forming apparatus. More specifically, the present invention relates to an image forming apparatus including a fixing device that fixes toner on an envelope produced by gluing a recording medium, and a control program for the image forming apparatus.

  The electrophotographic image forming apparatus includes a scanner function, a facsimile function, a copying function, a function as a printer, a data communication function, and a server function, an MFP (Multi Function Peripheral), a facsimile apparatus, a copying machine, a printer, and the like. is there.

  An image forming apparatus generally forms an image on a sheet by the following method. The image forming apparatus forms an electrostatic latent image on an image carrier and develops the electrostatic latent image using a developing device to form a toner image. Next, the image forming apparatus transfers the toner image to a sheet and fixes the toner image on the sheet by a fixing device. Further, in the image forming apparatus, a toner image is formed on a photosensitive member, the toner image is transferred to an intermediate transfer belt using a primary transfer roller, and the toner image on the intermediate transfer belt is used using a secondary transfer roller. In some cases, the image is secondarily transferred to the paper. The image forming apparatus performs printing on various types of recording media including envelopes.

  Note that conventional techniques relating to envelope printing are disclosed, for example, in Patent Documents 1 and 2 below. In Patent Document 1 below, when an envelope with flap glue is set by the envelope setting section with flap glue, the heating temperature of the fixing roller is between the glass transition point and the melting point of the adhesive applied to the envelope with flap glue. An image forming apparatus provided with a control device that controls the temperature to be equal to or lower than the predetermined temperature is disclosed.

  In Patent Document 2 below, a fixing unit that heats and melts unfixed toner while fixing an envelope as a recording material carrying an unfixed toner image to the envelope and fixes the fixing nip load of the fixing unit is changed. Fixing nip load changing section, registration sensor that detects the length of the envelope in the conveyance direction, and envelope length detected by the registration sensor during the nip conveyance process of the envelope by the fixing section An image forming apparatus including a control circuit for relaxing a fixing nip load and a fixing linear velocity is disclosed.

JP 2006-258962 A JP 2012-013914 A

  In recent years, in order to be able to install the image forming apparatus in various places such as a desk side, the image forming apparatus has been made compact, and the path from the fixing device (fixing roller) to the paper discharge unit has become shorter. Yes. For this reason, immediately after the recording medium passes through the fixing device, the recording medium bends by hitting a paper discharge guide provided on the downstream side of the fixing device, thereby making the distance between the recording medium and the fixing device irregular and causing uneven heating on the recording medium. It became easy to occur.

  When the recording medium is an envelope, there has been a phenomenon in which undulation (wrinkle) occurs in parallel with the extending direction of the short side of the envelope (hereinafter, this phenomenon may be referred to as undulation). The cause of the undulation is that the glued portion of the envelope is locally melted by the heating unevenness and then hardens. The ease of waving was greatly different depending on the type of envelope.

  Note that due to the characteristic of the envelope that a plurality of sheets of paper are overlapped, it is necessary to raise the fixing temperature to some extent in order to reliably fix the toner to the envelope. For this reason, if the temperature of the fixing roller is uniformly controlled to a low temperature equal to or lower than the melting point of the adhesive as in the technique of Patent Document 1, the possibility of causing a toner fixing defect increases.

  SUMMARY An advantage of some aspects of the invention is that it provides an image forming apparatus and an image forming apparatus control program that can appropriately suppress the undulation of an envelope.

  An image forming apparatus according to one aspect of the present invention includes a fixing device that fixes toner on an envelope manufactured by gluing a recording medium, and gluing the envelope before fixing the toner on the envelope by the fixing device. Detection means for detecting the position, and control means for switching a fixing condition, which is a condition for fixing the toner on the envelope by the fixing device, according to the gluing position.

  Preferably, in the image forming apparatus, the fixing device includes two rotating bodies, and the toner is fixed on the envelope by passing the envelope through the nip portion of the two rotating bodies, and the envelope immediately after passing through the nip portion is removed. The guide unit further includes a guide unit, and the control unit switches, as a fixing condition, at least one of an amount of heat given to the envelope by the fixing device and a rush angle, and the rush angle is an envelope when the envelope rushes into the guide unit The angle formed by the traveling direction of the guide and the guide direction of the guide portion.

  Preferably, in the image forming apparatus, the control unit includes a speed control unit that switches a heat amount given to the envelope by the fixing device by switching a sheet passing speed that is a speed at which the envelope passes through the nip portion.

  Preferably, in the image forming apparatus, the speed control unit is configured to set a sheet passing speed of the envelope having a glue position at at least one end in a direction perpendicular to a sheet passing direction that is a direction in which the envelope passes through the nip portion. The paper feeding speed is set to be higher than that of an envelope that does not have a gluing position at the end in the direction perpendicular to the paper feeding direction.

  Preferably, in the image forming apparatus, the speed control unit is configured to determine a sheet passing speed of an envelope having a glue position at both ends in a direction perpendicular to a sheet passing direction that is a direction in which the envelope passes through the nip portion. However, it is faster than the sheet passing speed of the envelope having the glued position only at one end in the direction perpendicular to the sheet.

  Preferably, the image forming apparatus further includes a process unit that performs processing on the envelope before fixing the toner on the envelope by the fixing device, and the speed control unit is configured to switch the process unit when the sheet passing speed is switched. The process conditions that are the conditions of the processing to be performed are further switched.

  Preferably, in the image forming apparatus, the control unit includes a temperature control unit that switches a heat amount given to the envelope by the fixing unit by switching a fixing temperature that is a temperature of the fixing unit when fixing the envelope.

  Preferably, in the above image forming apparatus, the speed at which the envelope that performs printing with relatively high image quality passes through the nip portion is slower than the speed at which the envelope that performs printing with relatively low image quality passes through the nip portion. The means is an envelope for printing with relatively high image quality, and fixing the envelope having a gluing position at at least one end in a direction perpendicular to the paper passing direction, which is a direction in which the envelope passes through the nip portion. The temperature is set to be lower than the fixing temperature of an envelope that performs printing with relatively high image quality and does not have a gluing position at an end portion in a direction perpendicular to the paper passing direction.

  Preferably, in the image forming apparatus, the temperature control unit passes the fixing temperature of the envelope having a gluing position at at least one end in a direction perpendicular to the sheet passing direction, which is a direction in which the envelope passes through the nip portion. The fixing temperature is set lower than the fixing temperature of the envelope having no gluing position at the end in the direction perpendicular to the paper direction.

  Preferably, in the image forming apparatus, the temperature control unit sets the fixing temperature of the envelope having glued positions at both ends in a direction perpendicular to the sheet passing direction, which is a direction in which the envelope passes through the nip portion, in the sheet passing direction. On the other hand, the temperature is set lower than the fixing temperature of an envelope having a gluing position only at one end in a direction perpendicular to the direction.

  Preferably, in the image forming apparatus, the control unit includes a posture control unit that switches the entry angle by switching the posture of the guide unit.

  Preferably, in the image forming apparatus, the posture control unit reduces an increase in a plunging angle of an envelope having a gluing position at both ends in a direction perpendicular to a paper passing direction that is a direction in which the envelope passes through the nip portion. Thus, the posture of the guide unit is switched.

  Preferably, in the image forming apparatus, the control unit includes a nip portion control unit that switches the entry angle by switching the position of the nip portion.

  Preferably, in the image forming apparatus, the nip portion control unit is capable of mitigating an increase in a plunging angle of an envelope having a gluing position at both ends in a direction perpendicular to a sheet passing direction that is a direction in which the envelope passes through the nip portion. The position of the nip portion is switched as shown.

  Preferably, in the image forming apparatus, the fixing device further includes an excitation coil that generates a magnetic field by a flowing current and a demagnetization coil that cancels the magnetic field, and one of two rotating bodies is generated by an eddy current generated by a change in the magnetic field. The rotating body is heated, and the control means attaches the degaussing coil to the gluing position when the envelope has a gluing position at at least one end in a direction perpendicular to the paper passing direction, which is the direction in which the envelope passes through the nip. The demagnetization control means for canceling out the magnetic field at the position of one of the rotating bodies corresponding to the gluing position.

  Preferably, the image forming apparatus further includes a selection unit that accepts selection of whether or not to change the fixing condition according to the gluing position, and the control unit is configured to perform a sheet passing direction that is a direction in which the envelope passes through the nip portion. In the case where the envelope has a gluing position at at least one end in the vertical direction, when the selection unit accepts the selection not to switch the fusing condition according to the gluing position, the fixing condition according to the gluing position is changed. Do not switch.

  Preferably, in the image forming apparatus, the control unit does not switch the fixing condition according to the gluing position when the expected remaining life of the fixing device is longer than a predetermined value.

  Preferably, in the image forming apparatus, the detection unit includes a first detection unit that detects a gluing position of the envelope based on the set envelope type.

  Preferably, the image forming apparatus includes a second detection unit that detects a pasting position of the envelope based on the thickness of the envelope.

  Preferably, the image forming apparatus further includes an image reading unit that reads an image of the envelope, and the detection unit includes a third detection unit that detects a gluing position of the envelope based on the image read by the image reading unit. .

  An image forming apparatus control program according to another aspect of the present invention is a control program for an image forming apparatus including a fixing device that fixes toner onto an envelope produced by gluing a recording medium. Before fixing the toner on the envelope, a detection step for detecting the gluing position of the envelope, and a control step for switching a fixing condition that is a condition for fixing the toner on the envelope by the fixing device according to the gluing position. And let the computer run.

  According to the present invention, it is possible to provide an image forming apparatus and an image forming apparatus control program that can appropriately suppress the undulation of the envelope.

1 is a cross-sectional view schematically showing a configuration of a color tandem type image forming apparatus 1 according to a first embodiment of the present invention. FIG. 2 is a block diagram illustrating a control configuration of the image forming apparatus 1 according to the first embodiment of the present invention. It is sectional drawing which shows the structure of the heating roller 31 in the 1st Embodiment of this invention. FIG. 4 is a cross-sectional view illustrating a configuration of a fixing device 30 when viewed in a cross section taken along line IV-IV in FIG. 3. FIG. 2 is a diagram schematically showing a part of an electric circuit of a fixing device 30 in the first embodiment of the present invention. It is a figure explaining the cause which corrugation generate | occur | produces in envelope EL. It is a figure which shows the relationship between the kind of envelope, and the ease of generation | occurrence | production of a wave. 3 is a flowchart showing an operation of the image forming apparatus 1 in the first embodiment of the present invention. It is the 1st part of the flowchart which shows operation | movement of the image forming apparatus 1 in the 2nd Embodiment of this invention. It is a 2nd part of the flowchart which shows operation | movement of the image forming apparatus 1 in the 2nd Embodiment of this invention. 12 is a flowchart illustrating an operation of the image forming apparatus 1 according to the third embodiment of the present invention. FIG. 5 is a diagram showing a relationship between a discharge angle and a rush angle and a force received from the discharge guide 17. FIG. 10 is a cross-sectional view schematically showing switching of the posture of a paper discharge guide 17 in a fourth embodiment of the present invention. 14 is a flowchart illustrating an operation of the image forming apparatus 1 according to the fourth embodiment of the present invention. It is sectional drawing which shows typically the switching of the position of the nip part NP in the 5th Embodiment of this invention. 10 is a flowchart illustrating an operation of the image forming apparatus 1 according to a fifth embodiment of the present invention. It is a 1st part of the flowchart which shows operation | movement of the image forming apparatus 1 in the 6th Embodiment of this invention. It is a 2nd part of the flowchart which shows operation | movement of the image forming apparatus 1 in the 6th Embodiment of this invention. It is sectional drawing which shows the structure of the fixing device 30 in the 7th Embodiment of this invention. It is a figure which shows the structure of the fixing device 30 at the time of seeing from the direction shown by the arrow V in FIG. 18 is a flowchart showing an operation of the image forming apparatus 1 in the seventh embodiment of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  In the following embodiment, a case where the image forming apparatus is an MFP will be described. In addition to the MFP, the image forming apparatus may be a facsimile machine, a copier, a printer, or the like.

  [First Embodiment]

  First, the configuration of the image forming apparatus in the present embodiment will be described.

  FIG. 1 is a cross-sectional view schematically showing the configuration of a color tandem type image forming apparatus 1 according to the first embodiment of the present invention. Note that an arrow AR1 in FIG. 1 indicates the envelope conveyance direction (conveyance direction in the conveyance path TR1) when printing is performed by the image forming apparatus 1.

  Referring to FIG. 1, image forming apparatus 1 according to the present embodiment is an MFP, and mainly includes a sheet conveying unit 10, an image forming unit 20, and a fixing device 30. The image forming apparatus 1 may further include a finisher (finishing processing unit).

  The paper transport unit 10 includes a paper feed roller (first-stage paper feed roller) 11, a timing roller 12, a paper discharge roller 13a, a reverse roller 13b, ADU (Auto Duplex Unit) transport rollers 14 and 15, and a refeed. A paper roller 16, a paper discharge guide 17 (an example of a guide unit), a timing sensor 41, a paper discharge sensor 42, ADU transport sensors 43 and 44, and an electrostatic sensor 45 are included.

  The paper feed roller 11 feeds the recording medium from a paper feed cassette (not shown) to the transport path TR1.

  The timing roller 12 conveys the recording medium along the conveyance path TR1 by starting or stopping at a timing synchronized with the image.

  The paper discharge roller 13a is provided at a position on the most downstream side of the transport path TR1, and discharges the recording medium to the outside of the main body of the image forming apparatus 1.

  The reversing roller 13b is provided in the reversing path TR2 that exists on the upper side of the transport path TR1, and reverses the recording medium to be printed on both sides by switchback and transports it to the transport path TR3.

  The ADU transport rollers 14 and 15 transport the recording medium that performs double-sided printing along the transport path TR3.

  The refeed roller 16 is provided at a refeeding position on the most downstream side of the transport path TR3, and feeds the recording medium from the refeed position to the transport path TR1.

  The paper discharge guide (switching guide) 17 guides the recording medium that has passed through the fixing device 30 to the paper discharge rollers 13a or 13b by switching the conveyance path for conveying the recording medium between the conveyance path TR1 and the reverse path TR2. To do.

  The timing sensor 41 detects the recording medium at a position upstream of the timing roller 12 in the transport path TR1. The image forming apparatus 1 detects the length of the recording medium along the transport direction by counting the time from when the timing sensor 41 is turned on to when it is turned off.

  The paper discharge sensor 42 detects the recording medium at a position on the upstream side of the transport path TR1 with respect to the paper discharge roller 13a.

  ADU transport sensors 43 and 44 detect the recording medium on transport path TR3.

  The electrostatic sensor 45 has a detection position on the upstream side of the transport path TR1 from the fixing device 30 (for example, in the vicinity of the paper feed roller 11 or in the vicinity of the timing roller 12). The electrostatic sensor 45 detects the local thickness of the recording medium passing through the detection position, and detects the gluing position of the envelope when the envelope is the recording medium.

  The image forming unit 20 includes image forming units 21Y, 21M, 21C, and 21K, and primary transfer rollers 22a, 22b, 22c, and 22d (hereinafter, these may be collectively referred to as a primary transfer roller 22). The intermediate transfer belt 23 and the secondary transfer roller 24 are included.

  Each of the image forming units 21Y, 21M, 21C, and 21K is disposed at a predetermined interval along the extending direction of the intermediate transfer belt 23 in the lower portion of the intermediate transfer belt 23. Each of the image forming units 21Y, 21M, 21C, and 21K forms a YMCK toner image on the photoreceptor.

  Each of the primary transfer rollers 22a, 22b, 22c, and 22d is opposed to the respective photoreceptors of the image forming units 21Y, 21M, 21C, and 21K with the intermediate transfer belt 23 interposed therebetween. Each of the primary transfer rollers 22a, 22b, 22c, and 22d transfers the respective photoreceptors of the image forming units 21Y, 21M, 21C, and 21K to the intermediate transfer belt 23. On the intermediate transfer belt 23, YMCK toner images are sequentially superimposed to form a color image.

  The intermediate transfer belt 23 is an endless belt and is suspended by a plurality of rollers 25 so as not to be loosened. The roller 25 rotates counterclockwise in FIG. 1 to rotate the intermediate transfer belt 23, and the toner image formed on the intermediate transfer belt 23 is conveyed to the position of the secondary transfer roller 24.

  The secondary transfer roller 24 is provided at a position between the timing roller 12 and the fixing device 30 on the transport path TR1. The secondary transfer roller 24 transfers the toner image formed on the intermediate transfer belt 23 to a recording medium.

  The fixing device 30 includes a heating roller 31 and a pressure roller 32 (an example of two rotating bodies). The fixing device 30 rotates the heating roller 31 and the pressure roller 32, and passes the recording medium carrying the toner image through the nip portion between the heating roller 31 and the pressure roller 32, thereby causing the toner image on the recording medium. To fix.

  FIG. 2 is a block diagram showing a control configuration of the image forming apparatus 1 according to the first embodiment of the present invention.

  Referring to FIG. 2, the image forming apparatus 1 includes an engine unit 100 and a system controller unit 200. The engine unit 100 is a part that performs image formation. The engine unit 100 includes a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, a nonvolatile memory 104, a drive motor 105, a finishing motor 106, a scanner unit. 107 (an example of an image reading unit).

  Based on a control program stored in the ROM 102, the CPU 101 controls operations related to image formation in a unified manner while measuring timing. The CPU 101 smoothly executes operations such as execution of a print job. The CPU 101 also controls the recording medium conveyance speed, the temperature of the fixing device 30, the posture of the paper discharge guide 17 (switching of the switching unit), the nip angle of the fixing device 30, and the like.

  The ROM 102 stores a control program related to image formation and paper feed in a printing operation performed by the engine unit 100.

  A RAM 103 is a volatile memory and is a work area when the CPU 101 executes a control program.

  The non-volatile memory 104 serves as a data storage area when the CPU 101 executes the control program.

  The drive motor 105 drives various rollers.

  The finishing motor 106 drives the finisher when the image forming apparatus 1 includes the finisher.

  The scanner unit 107 reads an image of a document.

  The system controller unit 200 controls the entire image forming apparatus 1. The system controller unit 200 includes a CPU 201 and an operation panel 202. The CPU 201 instructs the CPU 101 in the engine unit 100 to execute printing or notifies the type of recording medium to be printed input through the operation panel 202.

  The operation panel 202 accepts various operations and displays various information. When the operation panel 202 receives an input of the type of a recording medium that is an object of image formation, the operation panel 202 notifies the CPU 201 of the input.

  FIG. 3 is a cross-sectional view showing the configuration of the heating roller 31 in the first embodiment of the present invention. FIG. 4 is a cross-sectional view showing a configuration of the fixing device 30 when viewed in a cross-section along the line IV-IV in FIG. 3. Although the main thermistor 36 is shown in FIG. 4 for convenience of explanation, the main thermistor 36 is not actually visible.

  Referring to FIG. 3, the fixing device 30 includes a heating roller 31, a pressure roller (fixing belt) 32, a heater 33, a middle thermistor 34, a protect thermistor 35, a main thermistor 36, and a heating thermostat 37. , Pad 39. The heating roller 31 has a sheet passing range RG.

  The heating roller 31 and the pressure roller 32 have a cylindrical shape and rotate around their respective rotation axes.

  The heater 33 is provided inside the heating roller 31 and heats the heating roller 31.

  Each of the middle thermistor 34, the protect thermistor 35, and the main thermistor 36 has different detection positions along the rotation axis of the heating roller 31 on the outer periphery of the heating roller 31. Each of the middle thermistor 34, the protect thermistor 35, and the main thermistor 36 outputs information indicating the temperature of the heating roller 31 at each detection position to the CPU 201.

  The heating thermostat 37 is provided on the outer periphery of the heating roller 31. The heating thermostat 37 interrupts the current flowing through the heater 33 when the temperature of the heating roller 31 exceeds a predetermined temperature, and prevents an abnormal temperature rise of the heating roller 31.

  The pad 39 is provided inside the pressure roller 32. The pad 39 presses the pressure roller 32 against the heating roller 31. Thereby, the heating roller 31 and the pressure roller 32 form the nip part NP.

  FIG. 5 is a diagram schematically showing a part of the electric circuit of the fixing device 30 according to the first embodiment of the present invention.

  Referring to FIG. 5, the thermistor TT corresponds to each of the middle thermistor 34, the protect thermistor 35, and the main thermistor 36. The thermistor TT and the electric resistance (voltage dividing resistor) R are connected in series between the voltage source (input voltage) IV of the image forming apparatus 1 and the ground potential GND. One end of the heater 33 is connected between the thermistor TT and the electric resistance R. The thermistor TT changes in resistance value with the temperature of the detection position. As a result, the potential of the terminal P between the electric resistance R and the thermistor TT changes. The CPU 101 detects the temperature at the detection position of the thermistor TT based on the potential of the terminal P.

  FIG. 6 is a diagram for explaining the cause of undulations in the envelope EL.

  Referring to FIG. 6, a paper discharge guide 17 is provided on the downstream side of transport path TR1 from nip portion NP in the vicinity of nip portion NP. The paper discharge guide 17 guides the recording medium immediately after passing through the nip NP.

  Hereinafter, a case where the recording medium to be printed by the image forming apparatus 1 is an envelope will be described unless otherwise specified. In general, an envelope is manufactured by bending a recording medium into a cylindrical shape and gluing a necessary portion.

  The tip of the envelope EL that has passed through the nip NP between the heating roller 31 and the pressure roller 32 abuts on the paper discharge guide 17 and is guided in the direction along the transport path TR1 (upper left in FIG. 6). When the envelope EL hits the paper discharge guide 17, the envelope EL is bent by receiving a force in the direction indicated by the arrow AR <b> 2 from the paper discharge guide 17. As a result, the distance between a part of the envelope EL and the heating roller 31 approaches, a part of the envelope EL is abnormally heated, and the glue (adhesive) present in the part is temporarily melted and then hardened. As a result, waviness (wrinkle) occurs at the location where the glue in the envelope EL is melted.

  FIG. 7 is a diagram showing the relationship between the type of envelope and the ease of occurrence of undulations.

  Referring to FIG. 7, there are various types of envelopes, and there are those that are glued at various positions.

  Envelope EL1 of FIG. 7A has paste positions WP1, WP2, and WP3 and an opening OP. The pasting positions WP1 and WP2 exist at both ends in the direction perpendicular to the transport direction (the direction indicated by the arrow AR1), and extend in parallel to the transport direction. The gluing position WP1 exists at the upper end in FIG. 7, and the gluing position WP2 exists at the lower end in FIG. The gluing position WP3 exists at an end portion on the downstream side in the transport direction, and extends in a direction perpendicular to the transport direction. The opening OP is an opening for putting things into the envelope.

  Envelope EL2 in FIG. 7B has gluing positions WP1 and WP3 and an opening OP.

  Envelope EL3 of FIG.7 (c) is an envelope with which the center part was glued, and has glueing position WP3 and WP4 and the opening part OP. The gluing position WP4 exists in the center of the direction perpendicular to the transport direction, and extends in parallel to the transport direction.

  Envelopes EL1, EL2, and EL3 are Japanese envelopes, whereas envelope EL4 in FIG. 7 (d) is a Western envelope. Envelope EL4 has gluing positions WP5 and WP6 and an opening OP. The pasting position WP5 extends from the upstream position in the transport direction at the upper end portion in FIG. 7 to the downstream position in the transport direction at the lower end portion in FIG. The gluing position WP6 extends from the upstream position in the transport direction at the lower end portion in FIG. 7 to the downstream position in the transport direction at the upper end portion in FIG.

  Hereinafter, as in the envelope of FIG. 7A, an envelope having the pasting positions WP1 and WP2 at both ends in the direction perpendicular to the conveying direction may be referred to as an end glued envelope. Further, as in the envelope of FIG. 7B, an envelope having a gluing position WP2 (or WP1) at one end in a direction perpendicular to the conveying direction and having no gluing position at the other end. May be referred to as a one-end glued envelope. Further, as in the envelopes of FIGS. 7C and 7D, an envelope having no gluing position at the end in the direction perpendicular to the conveying direction may be referred to as an envelope without gluing at the end. is there.

  A line LN1 indicates a position on the envelope EL that is close to the heating roller 31 by the force received from the paper discharge guide 17 when the leading edge of the envelope EL hits the paper discharge guide 17. Since the portion indicated by the line LN1 is abnormally heated, the glue melts and undulation occurs.

  In the envelope EL1, which is an envelope with glue at both ends, the glue melts at positions PO1 and PO2 that are both ends in the direction perpendicular to the transport direction, and undulation occurs. The waviness generated at each of the positions PO1 and PO2 extends toward the center of the envelope EL and is connected as a single line as indicated by an arrow AR3. As a result, the most prominent undulation occurs in the four envelopes.

  In the envelope EL2 which is an envelope with one end glued, the glue melts at the position PO3 which is the lower end in the direction perpendicular to the transport direction, and the undulation occurs. The wave generated at the position PO3 extends toward the center of the envelope EL as indicated by the arrow AR3, but is not connected to other waves. As a result, the second most significant undulation occurs in the four envelopes.

  In the envelope EL3, which is an envelope without gluing at the end, the glue melts at the position PO4, which is the central portion in the direction perpendicular to the conveying direction, and undulation occurs. However, the undulation generated at the position PO4 is corrected and eliminated by the upper and lower ends (ends where no undulation is generated) in the direction perpendicular to the conveyance direction. As a result, corrugation hardly occurs among the four envelopes.

  In the envelope EL4, which is an envelope without end glue, the glue melts at two positions PO5, which are the central portions in the direction perpendicular to the transport direction, to generate undulations. However, the undulation generated at each of the two positions PO5 is corrected and eliminated by the upper and lower ends (ends where no undulation is generated) in the direction perpendicular to the conveyance direction. As a result, corrugation hardly occurs among the four envelopes.

  As described above, the ease of occurrence of undulations differs depending on the glue position in the envelope. For this reason, the image forming apparatus 1 detects the gluing position of the envelope before fixing the toner on the envelope by the fixing device 30, and the fixing device 30 applies the toner to the envelope according to the detected gluing position. Changes the fixing condition, which is a condition for fixing. Fixing conditions include the amount of heat given to the envelope by the fixing device 30 and a rush angle described later.

  There are the following four methods as typical methods for detecting the pasting position of envelopes. These methods may be combined with each other.

  As a first method, the image forming apparatus 1 may detect the glue position of the envelope based on the type of envelope to be printed set through the operation panel 202. For example, when the set envelope type is “Long No. 3”, the image forming apparatus 1 is configured such that most of the “Long No. 3” envelopes distributed in the market are gluing envelopes at both ends. Based on this fact, it may be determined that the gluing positions of the envelopes are gluing positions WP1, WP2, and WP3 (the envelope to be printed is a gluing envelope on both ends).

  As a second method, the image forming apparatus 1 may detect the gluing position of the envelope based on the thickness of the envelope detected by the electrostatic sensor 45. The gluing position in the envelope is thicker than the other portions because the two recording media are stacked. Therefore, if the thickness distribution in the envelope is measured by the electrostatic sensor 45, a portion where the thickness is locally increased can be detected as a gluing position.

  As a third method, the image forming apparatus 1 may use the scanner unit 107 to read an image of an envelope to be printed before printing, and detect the glue position of the envelope based on the read image. The glue position on the envelope is a stack of two recording media, which is thicker than the thickness of the other parts, so that the image read using the scanner unit 107 has a locally large thickness. The image at the location is darker than the images at other locations. Therefore, based on the image read by the scanner unit 107, a portion where the thickness is locally increased can be detected as a gluing position.

  In particular, the image forming apparatus 1 has a mode for detecting the size of the recording medium by reading the image of the recording medium by the scanner unit 107 when the user does not know the size of the recording medium to be printed. Have When the third method is used, the gluing position may be detected using this mode. Specifically, before the envelope is placed in a paper feed cassette or a manual feed cassette and printing is started, the image of the envelope is read by the scanner unit 107, and the glue position is detected from the transmittance information of the read image. Also good.

  As a fourth method, the image forming apparatus 1 may directly accept the setting of the glue position of the envelope through the operation panel 202.

  In the present embodiment, the image forming apparatus 1 switches the amount of heat applied to the envelope by the fixing device 30 by switching the sheet passing speed, which is the speed at which the envelope passes through the nip portion NP. Specifically, when the type of the recording medium set through the operation panel 202 is “Long No. 3” envelope, the image forming apparatus 1 determines that the recording medium is an envelope with glue on both ends. The image forming apparatus 1 determines the sheet passing speed when the type of the recording medium set through the operation panel 202 is “Long No. 3”, and the type of the recording medium set through the operation panel 202 is “Long”. It is faster than the paper feeding speed for envelopes other than “No. 3”.

  Further, in the present embodiment, the image forming apparatus 1 further switches process conditions, which are processing conditions performed by the process unit, when the sheet passing speed is switched as described above. The process part is a part (primary transfer roller, secondary transfer roller, or the like) that performs processing related to image formation on the envelope. The process conditions are conditions for processing performed by the process unit on the envelope (transfer voltage applied to the primary transfer roller 22, transfer voltage applied to the secondary transfer roller 24, and the like). The process conditions are appropriately set according to the sheet passing speed.

  FIG. 8 is a flowchart showing the operation of the image forming apparatus 1 according to the first embodiment of the present invention.

  Referring to FIG. 8, when receiving an instruction to execute printing (S101), CPU 101 determines whether or not the set recording medium (medium) is an envelope (S103).

  If it is determined in step S103 that the set recording medium type is not an envelope (NO in S103), the CPU 101 determines whether the set recording medium type is plain paper (S105).

  If it is determined in step S105 that the set recording medium type is not plain paper (NO in S105), the CPU 101 determines that the set recording medium type is thick paper. The CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s) (S107). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is cardboard (S109). Subsequently, the CPU 101 executes printing (S111) and ends the process.

  If it is determined in step S105 that the set recording medium type is plain paper (YES in S105), the CPU 101 sets the sheet passing speed of the recording medium to a high speed (for example, 230 mm / s) (S113). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is high, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a high sheet passing speed. Yes, and set to an output value when the recording medium is plain paper (S115). Subsequently, the CPU 101 executes printing (S111) and ends the process.

  If it is determined in step S103 that the set type of the recording medium is an envelope (YES in S103), the CPU 101 determines whether the set type of the recording medium is a long No. 3 envelope. (S117).

  If it is determined in step S117 that the set type of the recording medium is not the long No. 3 envelope (NO in S117), the CPU 101 determines that the recording medium is not a gluing envelope on both ends. The CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s) (S119). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S121). Subsequently, the CPU 101 executes printing (S111) and ends the process.

  If it is determined in step S117 that the set type of the recording medium is the long No. 3 envelope (YES in S117), the CPU 101 determines that the recording medium is a double-sided glue envelope. The CPU 101 sets the sheet passing speed of the recording medium to a high speed (for example, 230 mm / s) (S123). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is high, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a high sheet passing speed. Yes, and set to an output value when the recording medium is an envelope (S125). Subsequently, the CPU 101 executes printing (S111) and ends the process.

  According to the present embodiment, by increasing the sheet passing speed, the amount of heat applied from the fixing device 30 to the “long size 3” envelope can be reduced, and the corrugation of the glued envelope can be suppressed. . On the other hand, by slowing the sheet passing speed, the amount of heat given from the fixing device 30 to the envelope that is not “Long 3” is increased, and there is a possibility of causing poor toner fixing during printing of the envelope that is not glued at both ends. Can be reduced. As a result, the ripples of the envelope can be appropriately suppressed.

  [Second Embodiment]

  In the present embodiment, the image forming apparatus 1 switches the amount of heat applied to the envelope by the fixing device 30 by switching the sheet passing speed, which is the speed at which the envelope passes through the nip portion NP. Specifically, the image forming apparatus 1 has a paper passing speed when the type of the recording medium is a double-end glued envelope, and is faster than a paper feeding speed when the type of the recording medium is a single-end glued envelope. To do. In addition, the image forming apparatus 1 uses a paper feeding speed when the recording medium type is an envelope with glue at both ends or an envelope with glue at one end, and when the recording medium type is an envelope without glue at the edge. Make it faster than the paper feed speed.

  9 and 10 are flowcharts showing the operation of the image forming apparatus 1 in the second embodiment of the present invention.

  Referring to FIG. 9, each process of steps S201 to S215 in this flowchart is substantially the same as each of steps S101 to S115 of the flowchart shown in FIG. 8, and therefore description thereof will not be repeated.

  If it is determined in step S203 that the type of the set recording medium (medium) is an envelope (YES in S203), the CPU 101 detects the gluing position using the second to fourth methods described above, and the like. It is determined whether or not the recording medium is an envelope with glue on both ends (S217).

  If it is determined in step S217 that the recording medium is an envelope with glue at both ends (YES in S217), the CPU 101 sets the sheet passing speed of the recording medium to a high speed (for example, 230 mm / s) (S219). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is high, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a high sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S221). Subsequently, the CPU 101 executes printing (S211) and ends the process.

  If it is determined in step S217 that the recording medium is not a double-end glued envelope (NO in S217), the CPU 101 proceeds to the process of step S223 in FIG.

  Referring to FIG. 10, in step S223, the CPU 101 detects the gluing position using the second to fourth methods described above, and determines whether or not the recording medium is a single-end gluing envelope ( S223).

  If it is determined in step S223 that the recording medium is a single-end glued envelope (YES in S223), the CPU 101 sets the sheet passing speed of the recording medium to a medium speed (for example, 173 mm / s) (S225). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is medium, and sets the transfer voltage to be applied to the secondary transfer roller 24 to the medium passing speed. The output value is set when the recording speed is an envelope and the recording medium is an envelope (S227). Subsequently, the CPU 101 executes printing (S211 in FIG. 9) and ends the process.

  If it is determined in step S223 that the recording medium is not a single-end glued envelope (NO in S223), the CPU 101 determines that the recording medium is an envelope without a glued edge. The CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s) (S229). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S231). Subsequently, the CPU 101 executes printing (S211 in FIG. 9) and ends the process.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, by increasing the sheet passing speed, the amount of heat given from the fixing device 30 to the envelope with glue at both ends is made smaller than the amount of heat given from the fuser 30 to the envelope with glue at one end. In addition, it is possible to suppress the corrugation of the glued envelope at both ends. Also, by increasing the sheet passing speed, the amount of heat given from the fixing device 30 to the envelope with one end glued is less than the amount of heat given from the fixing device 30 to the envelope without edge glued, and the one end glued Envelope undulation can be suppressed. Further, by reducing the sheet passing speed, the amount of heat applied from the fixing device 30 to the envelope without edge glue is increased, and the possibility of causing poor toner fixing during printing of the envelope without edge glue is reduced. be able to. As a result, the ripples of the envelope can be appropriately suppressed.

  [Third Embodiment]

  In the present embodiment, the image forming apparatus 1 switches the amount of heat applied to the envelope by the fixing device 30 by switching the fixing temperature, which is the temperature of the fixing device 30 when fixing the envelope. Specifically, the image forming apparatus 1 sets the fixing temperature when the type of the recording medium is a double-end glued envelope to be lower than the fixing temperature when the type of the recording medium is a single-end glued envelope. Further, the image forming apparatus 1 fixes the fixing temperature when the recording medium type is an envelope with glue on both ends or the envelope with a glue on one end, and fixing when the type of recording medium is an envelope without glue on the edge. Lower than temperature.

  FIG. 11 is a flowchart showing the operation of the image forming apparatus 1 according to the third embodiment of the present invention.

  Referring to FIG. 11, upon receiving an instruction to execute printing in which the recording medium is an envelope (S301), CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s) (S303). Next, the CPU 101 conveys the recording medium to the position of the timing roller (S305), and detects the gluing position of the recording medium using the electrostatic sensor 45 (using the second method) (S307). Subsequently, the CPU 101 determines whether or not the recording medium is a double-sided glued envelope (S309).

  If it is determined in step S309 that the recording medium is a double-sided glue envelope (YES in S309), the CPU 101 sets the fixing temperature to a low temperature (for example, 160 degrees) (S311). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S313). Subsequently, the CPU 101 executes printing (S315) and ends the process.

  If it is determined in step S309 that the recording medium is not a double-end glued envelope (NO in S309), the CPU 101 determines whether the recording medium is a single-end glued envelope (S317).

  If it is determined in step S317 that the recording medium is a single-end glued envelope (YES in S317), the CPU 101 sets the fixing temperature to an intermediate temperature (for example, 180 degrees) (S319), and proceeds to the process in step S313.

  If it is determined in step S317 that the recording medium is not a one-end glued envelope (NO in S317), the CPU 101 determines that the recording medium is an envelope without edge glued. The CPU 101 sets the fixing temperature to a high temperature (for example, 195 degrees) (S321), and proceeds to the process of step S313.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, by setting the fixing temperature to a low temperature, the amount of heat given from the fixing device 30 to the double-end glued envelope is less than the amount of heat given from the fixing device 30 to the single-end glued envelope. In addition, it is possible to suppress the corrugation of the envelope with the glue at both ends. Further, by setting the fixing temperature to an intermediate temperature, the amount of heat given from the fixing device 30 to the envelope with one end glued is less than the amount of heat given from the fuser 30 to the envelope without edge glued, and the one end glued Can suppress the undulation of the envelope. Further, by increasing the fixing temperature, the amount of heat given from the fixing device 30 to the envelope without end glue is increased, and the possibility of causing poor toner fixing during printing of the envelope without edge glue is reduced. be able to. As a result, the ripples of the envelope can be appropriately suppressed.

  [Fourth Embodiment]

  FIG. 12 is a diagram illustrating the relationship between the discharge angle and the entry angle and the force received from the discharge guide 17.

  Referring to FIG. 12, an angle formed by the recording medium M discharged from the nip portion NP and the horizontal direction and increasing as the recording medium M tilts toward the pressure roller 32 is defined as a discharge angle θ1. Further, the angle formed by the traveling direction of the recording medium M when the recording medium M enters the paper discharge guide 17 and the guide direction of the paper discharge guide 17 is defined as a rush angle θ2.

  When the recording medium M is an envelope in which undulation is likely to occur, the discharge angle θ1 increases and the entry angle θ2 tends to increase compared to the case in which the recording medium M is an envelope in which undulation does not occur easily. As a result, the force that the recording medium M receives from the paper discharge guide 17 (the force indicated by the arrow AR2) is increased, the recording medium M is bent, and heating unevenness is likely to occur in the recording medium M.

  From this fact, if the entry angle θ2 is reduced, the force received by the recording medium M from the paper discharge guide 17 is reduced, heating unevenness is less likely to occur, and even when the recording medium M is an envelope in which undulation is likely to occur. It can be seen that the occurrence of undulation can be suppressed.

  In the present embodiment, the image forming apparatus 1 switches the entry angle by switching the posture of the paper discharge guide 17. Specifically, the image forming apparatus 1 switches the posture of the paper discharge guide 17 so that the increase in the rush angle when the recording medium is a double-sided glued envelope is alleviated.

  FIG. 13 is a cross-sectional view schematically showing the switching of the posture of the paper discharge guide 17 in the fourth embodiment of the present invention.

  Referring to FIG. 13, here there are two paper discharge guides 17. Each of the paper discharge guides 17 can be swung around the end portion, and the posture can be switched between the position PT1 and the position PT2 as indicated by an arrow AR4. The position PT1 is a default position of the paper discharge guide 17. When the paper discharge guide 17 is at the position PT1, the paper discharge guide 17 guides the recording medium to the transport path TR1. When the paper discharge guide 17 is at the position PT2, the paper discharge guide 17 guides the recording medium to the reverse path TR2.

  The image forming apparatus 1 positions the paper discharge guide 17 at the position PT1 when the recording medium is not an envelope with glue at both ends. In this case, the recording medium is transported along the transport path TR1 and discharged to the outside of the main body of the image forming apparatus 1 by the paper discharge roller 13a.

  On the other hand, the image forming apparatus 1 switches the paper discharge guide 17 to the position PT2 when the recording medium is an envelope with glue at both ends. When the discharge angle is the same, the position PT2 is a position where the entry angle is smaller than the position PT1. When the recording medium is a double-sided glued envelope, the discharge angle is expected to increase. Therefore, by increasing the discharge guide 17 to the position PT2, the increase in the entry angle is mitigated. In this case, the both end glued envelopes are conveyed along the reversing path TR2 and discharged to the outside of the main body of the image forming apparatus 1 by the reversing rollers 13b.

  The image forming apparatus 1 switches the posture of the paper discharge guide 17 so that the entry angle when the recording medium is not a glued envelope at both ends and the entry angle when the recording medium is a glued envelope at both ends are equal. It is preferable.

  FIG. 14 is a flowchart showing the operation of the image forming apparatus 1 according to the fourth embodiment of the present invention.

  Referring to FIG. 14, when CPU 101 receives an instruction to execute printing in which the recording medium is an envelope (S401), CPU 101 sets the sheet passing speed of the recording medium to a low speed (eg, 115 mm / s) (S403). Next, the CPU 101 conveys the recording medium to the position of the timing roller (S405), and detects the gluing position of the recording medium using the electrostatic sensor 45 (using the second method) (S407). Subsequently, the CPU 101 determines whether or not the recording medium is a double-sided glued envelope (S409).

  If it is determined in step S409 that the recording medium is a double-sided glue envelope (YES in S409), the CPU 101 switches the position of the paper discharge guide 17 to the position PT2 (S411), and proceeds to the process of step S413.

  If it is determined in step S409 that the recording medium is not a double-end glued envelope (NO in S409), the CPU 101 keeps the position of the paper discharge guide 17 at the default position PT1, and proceeds to the process of step S413.

  In step S413, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to be the sheet passing speed. The output value is set when the recording speed is low speed and the recording medium is an envelope (S413). Subsequently, the CPU 101 executes printing (S415) and ends the process.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, an increase in the entry angle can be suppressed even when the discharge angle of the envelope with the glue at both ends is large, and undulation can be suppressed.

  [Fifth Embodiment]

  In the present embodiment, the image forming apparatus 1 switches the entry angle by switching the position of the nip portion NP. Specifically, the image forming apparatus 1 switches the posture of the nip portion NP so that the increase in the rush angle when the recording medium is a double-end glued envelope is alleviated.

  FIG. 15 is a cross-sectional view schematically showing switching of the position of the nip portion NP in the fifth embodiment of the present invention.

  Referring to FIG. 15, pressure roller 32 is movable between position PT11 and position PT12 as indicated by arrow AR5. The position PT11 is a default position of the pressure roller 32. As shown in FIG. 15A, when the pressure roller 32 is at the position PT11, the nip portion NP is positioned on the upstream side of the transport path TR1, and the fixing device 30 is a recording medium in the direction indicated by the arrow AR6. Is discharged. On the other hand, as shown in FIG. 15B, when the pressure roller 32 is at the position PT12, the nip portion NP is switched to a position downstream of the transport path TR1 from the position in FIG. 15A. The fixing device 30 discharges the recording medium in the direction indicated by the arrow AR7.

  The image forming apparatus 1 positions the pressure roller 32 at the position PT11 when the recording medium is not an envelope with glue at both ends.

  On the other hand, the image forming apparatus 1 moves the pressure roller 32 to the position PT12 when the recording medium is an envelope with glue at both ends. When the pressure roller 32 is located at the position PT12, the discharge angle is smaller than when the pressure roller 32 is located at the position PT11. Therefore, when the recording medium is a double-sided glued envelope, the increase in the discharge angle and the entry angle is mitigated by setting the pressure roller 32 to the position PT12.

  The image forming apparatus 1 preferably switches the nip portion NP so that the discharge angle when the recording medium is not a double-end glued envelope and the discharge angle when the recording medium is a double-end glued envelope are equal. .

  The specific means for switching the nip part NP is preferably constituted by a motor, a pinion, an arc-shaped rack or the like. An arc-shaped rack is attached to the end of the rotating shaft of the pressure roller 32, and the pinion connected to the motor rotates, whereby the pressure roller 32 moves in an arc shape and the nip portion NP can be moved. The switching of the nip portion NP may be performed when the recording medium is being passed through the nip portion NP, or may be performed in advance before the recording medium enters the nip portion NP.

  FIG. 16 is a flowchart showing the operation of the image forming apparatus 1 according to the fifth embodiment of the present invention.

  Referring to FIG. 16, the processes in steps S501 to S507 in this flowchart are substantially the same as those in steps S401 to S407 in the flowchart shown in FIG. 14, and therefore description thereof will not be repeated.

  Subsequent to the processing in step S507, the CPU 101 determines whether or not the recording medium is a double-sided glued envelope (S509).

  If it is determined in step S509 that the recording medium is a double-sided glue envelope (YES in S509), the CPU 101 moves the nip NP to the downstream side of the transport path TR1 by moving the pressure roller 32 to the position PT12. (S511), the process proceeds to step S513.

  If it is determined in step S509 that the recording medium is not a double-end glued envelope (NO in S509), the CPU 101 does not move the nip portion NP by leaving the position of the pressure roller 32 at the default position PT11. The process proceeds to step S513.

  In step S513, the CPU 101 sets the transfer voltage applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage applied to the secondary transfer roller 24 to the sheet passing speed. The output value is set when the recording speed is low speed and the recording medium is an envelope (S513). Subsequently, the CPU 101 executes printing (S515) and ends the process.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, it is possible to suppress an increase in the discharge angle and the entry angle of the envelope with the glue at both ends, and it is possible to suppress undulations.

  [Sixth Embodiment]

  As a premise of the present embodiment, the image forming apparatus 1 makes the paper passing speed of an envelope that performs printing with relatively high image quality slower than the paper passing speed of an envelope that performs printing with relatively low image quality. This is because when printing is performed with a relatively high image quality, the printing process takes more time than when printing is performed with a relatively low image quality.

  When the image forming apparatus 1 has the above-described configuration, when the envelope is printed with a relatively high image quality, it is not possible to increase the sheet passing speed as in the first embodiment.

  Therefore, in the present embodiment, the image forming apparatus 1 is an envelope that performs printing with a relatively high image quality, and performs printing with a relatively high image quality at the fixing temperature of the both-end glued or one-end glued envelope. The envelope is made lower than the fixing temperature of the envelope without end gluing.

  FIGS. 17 and 18 are flowcharts showing the operation of the image forming apparatus 1 in the sixth embodiment of the invention.

  Referring to FIG. 17, the processes in steps S601 to S615 in this flowchart are substantially the same as those in steps S101 to S115 in the flowchart shown in FIG. 8, and therefore description thereof will not be repeated.

  If it is determined in step S603 that the set type of the recording medium (medium) is an envelope (YES in S603), the CPU 101 determines whether or not the set type of the recording medium is a long type 3 envelope. Is discriminated (S617).

  If it is determined in step S617 that the type of the set recording medium is not the long No. 3 envelope (NO in S617), the CPU 101 determines that the recording medium is not a glued envelope on both ends. The CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s), and sets the fixing temperature to a high temperature (for example, 195 degrees) (S619). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S621). Subsequently, the CPU 101 executes printing (S611) and ends the process.

  If it is determined in step S617 that the set type of the recording medium is a long-size 3 envelope (YES in S617), the CPU 101 determines that the recording medium is a double-sided glued envelope, and FIG. The process proceeds to step S623.

  Referring to FIG. 18, in step S623, CPU 101 determines whether or not the set printing condition is high image quality (eg, 1200 dpi) (S623).

  If it is determined in step S623 that the set printing condition is not high image quality (NO in S623), the CPU 101 sets the sheet passing speed of the recording medium to a high speed (for example, 230 mm / s) and sets the fixing temperature to a high temperature (for example, 230 mm / s). For example, it is set to 195 degrees (S625). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is high, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a high sheet passing speed. Yes, and set to an output value when the recording medium is an envelope (S627). Subsequently, the CPU 101 executes printing (S611 in FIG. 17) and ends the process.

  If it is determined in step S623 that the set printing condition is high image quality (YES in S623), the CPU 101 sets the sheet passing speed of the recording medium to a low speed (for example, 115 mm / s) and sets the fixing temperature to a low temperature. (For example, 165 degrees) is set (S629). Next, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to have a low sheet passing speed. Yes, and set to the output value when the recording medium is an envelope (S631). Subsequently, the CPU 101 executes printing (S611 in FIG. 17) and ends the process.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, it is possible to suppress undulation even when printing an envelope with high image quality.

  [Seventh Embodiment]

  In the present embodiment, when the recording medium is a double-end glued or one-end glued envelope, the image forming apparatus 1 moves the position of the heating roller 31 corresponding to the glued position by bringing the degaussing coil closer to the glued position. Counteract the magnetic field.

  FIG. 19 is a cross-sectional view showing the configuration of the fixing device 30 according to the seventh embodiment of the present invention. FIG. 20 is a diagram illustrating the configuration of the fixing device 30 when viewed from the direction indicated by the arrow V in FIG.

  Referring to FIGS. 19 and 20, fixing device 30 in the present embodiment is an IH fixing device that heats heating roller 31 using the principle of IH (Induction Heating). The fixing device 30 includes, instead of the heater, an exciting coil 38a that generates a magnetic field by a flowing current and a demagnetizing coil 38b that cancels the magnetic field generated from the exciting coil 38a. An eddy current is generated in the heating roller 31 due to a change in the magnetic field from the exciting coil 38a, and the heating roller 31 is heated by this eddy current.

  The demagnetizing coil 38b is movable between the position PT21 and the position PT22 as indicated by an arrow AR8 under the control of the CPU 101. The position PT21 is a default position of the degaussing coil 38b, and is a position outside the both ends of the envelope EL in the horizontal direction in FIG. 18 (direction perpendicular to the paper passing direction indicated by the arrow AR1). The position PT22 is a position inside the both ends of the envelope EL in the horizontal direction in FIG.

  The image forming apparatus 1 supplies a current to the exciting coil 38a and heats the heating roller 31 with a magnetic field generated from the exciting coil 38a. The image forming apparatus 1 positions the degaussing coil 38b at the position PT21 when the recording medium is an envelope without end glue. When the demagnetizing coil 38b exists at a position outside the both ends of the envelope EL in the horizontal direction in FIG. 18, the magnetic field at the position of the heating roller 31 in the region through which the envelope EL passes is not affected by the demagnetizing coil 38b. Accordingly, the heating roller 31 in the region through which the envelope EL passes is heated uniformly.

  On the other hand, the image forming apparatus 1 moves the degaussing coil 38b to the position PT22 when the recording medium is a double-end glued envelope or a single-end glue envelope. When the recording medium is a single-end glued envelope, only the demagnetizing coil 38b on the side where the glued position exists may be moved. When the demagnetizing coil 38b exists at a position inside the both ends of the envelope EL in the lateral direction in FIG. 18, the magnetic field of the heating roller 32 in the region through which the gluing position passes is canceled by the demagnetizing coil 38b. As a result, the temperature of the heating roller 31 in the region through which the gluing position passes is lower than the temperature of the heating roller 31 in the region through which the portion other than the gluing position in the envelope EL passes.

  FIG. 21 is a flowchart showing the operation of the image forming apparatus 1 according to the seventh embodiment of the present invention.

  Referring to FIG. 21, the processes in steps S701 to S707 in this flowchart are substantially the same as those in steps S401 to S407 in the flowchart shown in FIG. 14, and therefore description thereof will not be repeated.

  Subsequent to the processing in step S707, the CPU 101 determines whether the recording medium is a double-sided glue or a single-end glued envelope (S709).

  If it is determined in step S709 that the recording medium is a double-sided or one-end glued envelope (YES in S709), the CPU 101 moves the degaussing coil 38b to a position PT22 that is directly above the glued position (S711). The process proceeds to step S713.

  If it is determined in step S709 that the recording medium is neither a double-end glued envelope nor a single-end glued envelope (NO in S709), the CPU 101 keeps the position of the demagnetizing coil 38b at the default position PT21, and in step S713. Proceed to processing.

  In step S713, the CPU 101 sets the transfer voltage to be applied to the primary transfer roller 22 to an output value when the sheet passing speed is low, and sets the transfer voltage to be applied to the secondary transfer roller 24 to be the sheet passing speed. The output value is set when the recording speed is low speed and the recording medium is an envelope (S713). Subsequently, the CPU 101 executes printing (S715) and ends the process.

  Note that the configuration of the image forming apparatus 1 in the present embodiment and operations other than those described above are the same as the configuration and operation of the image forming apparatus in the first embodiment, and therefore the same members are denoted by the same reference numerals. The description will not be repeated.

  According to the present embodiment, since the magnetic field at the gluing position in the envelope disappears and the heating roller 31 is not heated, heating of the gluing position in the envelope can be locally suppressed, and undulation can be suppressed. .

  [Others]

  In order to minimize toner fixing failure caused by reducing the amount of heat applied to the envelope, the image forming apparatus 1 switches the fixing conditions according to the gluing position through the operation panel 202 (first to seventh embodiments). The selection of necessity / unnecessity of the fixing condition described in (1) may be accepted. The image forming apparatus 1 switches the fixing condition according to the gluing position when receiving the selection not to switch the fixing condition according to the gluing position in the case of printing the double-sided gluing envelope or the one-end gluing envelope. When the selection for switching the fixing condition according to the gluing position is accepted without performing the above, the fixing condition may be switched according to the gluing position.

  In general, the pressure roller 32 tends to deteriorate and soften as the total number of printed sheets (number of uses) increases, and the discharge angle tends to increase. For this reason, the image forming apparatus 1 has a case where the expected remaining life of the fixing device 30 is longer than a predetermined value (for example, the total number of printed sheets of the pressure roller 32 is less than a threshold (for example, 7000 sheets)). ), The switching of the fixing conditions according to the gluing position (the switching of the fixing conditions described in the first to seventh embodiments) is not performed, and the expected remaining life of the fixing device 30 is greater than a predetermined value. When it is short (for example, when the total number of printed sheets of the pressure roller 32 exceeds the threshold value), the fixing condition is switched according to the gluing position (the fixing condition switching described in the first to seventh embodiments). May be performed.

  The above-described embodiments can be combined as appropriate.

  The processing in the above-described embodiment may be performed by software or by using a hardware circuit. It is also possible to provide a program for executing the processing in the above-described embodiment, and record the program on a recording medium such as a CD-ROM, a flexible disk, a hard disk, a ROM, a RAM, or a memory card and provide it to the user. You may decide to do it. The program is executed by a computer such as a CPU. The program may be downloaded to the apparatus via a communication line such as the Internet.

  The above-described embodiment is to be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 10 Paper conveyance part 11 Paper feed roller 12 Timing roller 13a Paper discharge roller 13b Inversion roller 14,15 ADU (Auto Duplex Unit) conveyance roller 16 Re-feed roller 17 Paper discharge guide (an example of a guide part)
20 Image forming unit 21Y, 21M, 21C, 21K Image forming unit 22, 22a, 22b, 22c, 22d Primary transfer roller 23 Intermediate transfer belt 24 Secondary transfer roller 25 Rotating roller 30 Fixing device 31 Heating roller 32 Pressure roller 33 Heater 34 Middle thermistor 35 Protect thermistor 36 Main thermistor 37 Heating thermostat 38a Excitation coil 38b Degaussing coil 39 Pad 40 Fixing device 41 Timing sensor 42 Paper discharge sensor 43, 44 ADU conveyance sensor 45 Electrostatic sensor 100 Engine unit 101 CPU (Central Processing Unit) )
102 ROM (Read Only Memory)
103 RAM (Random Access Memory)
104 Non-volatile memory 105 Drive motor 106 Finishing motor 107 Scanner section (an example of image reading means)
200 System controller 202 Operation panel EL, EL1, EL2, EL3, EL4 Envelope GND Ground potential LN1 In the envelope in which the distance from the heating roller approaches due to the force received from the discharge guide when the tip of the envelope hits the discharge guide Location M Recording medium NP Fixing device nip OP Opening of envelope P Terminal PO1, PO2, PO3, PO4, PO5 Position where undulation occurs PT1, PT2, PT11, PT12, PT21, PT22 Position R Electric resistance RG Paper feeding range TR1, TR3 Transport path TR2 Reverse path TT Thermistor WP1, WP2, WP3, WP4, WP5, WP6 Gluing position θ1 Discharge angle θ2 Penetration angle

Claims (21)

A fixing device for fixing toner on an envelope produced by gluing a recording medium;
Detecting means for detecting a gluing position of the envelope before fixing the toner on the envelope by the fixing device;
An image forming apparatus comprising: a control unit that switches a fixing condition, which is a condition for fixing toner on the envelope by the fixing device, according to the gluing position. The fixing device includes two rotating bodies, and fixes the toner on the envelope by passing the envelope through a nip portion of the two rotating bodies,
A guide portion for guiding the envelope immediately after passing through the nip portion;
The control means switches, as the fixing condition, at least one of an amount of heat given to the envelope by the fixing device and a rush angle,
The image forming apparatus according to claim 1, wherein the entry angle is an angle formed by a traveling direction of the envelope and a guide direction of the guide portion when the envelope enters the guide portion.   The image forming apparatus according to claim 2, wherein the control unit includes a speed control unit that switches a heat amount given to the envelope by the fixing device by switching a sheet passing speed that is a speed at which the envelope passes through the nip portion. apparatus.   The speed control means is configured to control the sheet passing speed of the envelope having the gluing position at at least one end in a direction perpendicular to a sheet passing direction that is a direction in which the envelope passes through the nip portion. The image forming apparatus according to claim 3, wherein the sheet passing speed of the envelope not having the gluing position at an end portion in a direction perpendicular to the paper direction is set to be higher.   The speed control means sets the sheet passing speed of the envelope having the gluing position at both ends in a direction perpendicular to the sheet passing direction, which is a direction in which the envelope passes through the nip portion, in the sheet passing direction. 5. The image forming apparatus according to claim 3, wherein the sheet passing speed of the envelope having the gluing position only at one end in a direction perpendicular to the envelope is faster than the sheet passing speed. A process unit for performing processing on the envelope before fixing the toner on the envelope by the fixing device;
The image forming apparatus according to claim 3, wherein the speed control unit further switches a process condition that is a condition of processing performed by the process unit when the sheet passing speed is switched.   The control unit includes a temperature control unit that switches a heat amount that the fixing unit gives to the envelope by switching a fixing temperature that is a temperature of the fixing unit when fixing the envelope. An image forming apparatus according to claim 1. The speed at which the envelope that performs printing with relatively high image quality passes through the nip portion is slower than the speed at which the envelope that performs printing with relatively low image quality passes through the nip portion,
The temperature control means is the envelope that performs printing with relatively high image quality, and the temperature control means is provided at at least one end in a direction perpendicular to a paper passing direction that is a direction in which the envelope passes through the nip portion. The envelope that performs printing with a relatively high image quality at the fixing temperature of the envelope having a gluing position, and does not have the gluing position at an end in a direction perpendicular to the paper passing direction. The image forming apparatus according to claim 7, wherein the image forming apparatus is lower than the fixing temperature.   The temperature control means is configured to set the fixing temperature of the envelope having the gluing position at at least one end in a direction perpendicular to a paper passing direction, which is a direction in which the envelope passes through the nip portion. The image forming apparatus according to claim 7, wherein the image forming apparatus is configured to be lower than the fixing temperature of the envelope not having the gluing position at an end portion in a direction perpendicular to the direction.   The temperature control means sets the fixing temperature of the envelope having the gluing position at both ends in a direction perpendicular to the paper passing direction, which is a direction in which the envelope passes through the nip portion, with respect to the paper passing direction. The image forming apparatus according to claim 7, wherein the temperature is lower than the fixing temperature of the envelope having the gluing position only at one end in a vertical direction.   The image forming apparatus according to claim 2, wherein the control unit includes a posture control unit that switches the entry angle by switching a posture of the guide unit.   The posture control means is configured to mitigate an increase in the entry angle of the envelope having the gluing position at both ends in a direction perpendicular to a paper passing direction that is a direction in which the envelope passes through the nip portion. The image forming apparatus according to claim 3, wherein the posture of the guide unit is switched.   The image forming apparatus according to claim 2, wherein the control unit includes a nip unit control unit that switches the entry angle by switching a position of the nip unit.   The nip control means is configured to mitigate an increase in the entry angle of the envelope having the gluing position at both ends in a direction perpendicular to a paper passing direction, which is a direction in which the envelope passes through the nip. The image forming apparatus according to claim 13, wherein the position of the nip portion is switched. The fixing device further includes an exciting coil that generates a magnetic field by a flowing current, and a degaussing coil that cancels the magnetic field,
One of the two rotating bodies is heated by the eddy current generated by the change in the magnetic field,
The control means attaches the demagnetizing coil to the demagnetizing coil when the envelope has the gluing position at at least one end in a direction perpendicular to a paper passing direction, which is a direction in which the envelope passes through the nip portion. The image forming apparatus according to claim 2, further comprising a demagnetization control unit that cancels a magnetic field at the position of the one rotating body corresponding to the gluing position by approaching the position. A selection means for receiving selection of whether or not to switch the fixing conditions according to the gluing position;
The control means corresponds to the gluing position when the envelope has the gluing position at at least one end in a direction perpendicular to a paper passing direction that is a direction through which the envelope passes through the nip portion. The image forming apparatus according to claim 2, wherein when the selection unit accepts selection not to switch the fixing condition, the fixing condition is not switched according to the gluing position.   17. The control unit according to claim 1, wherein the fixing unit does not switch the fixing condition according to the gluing position when the predicted remaining life of the fixing device is longer than a predetermined value. Image forming apparatus.   The image forming apparatus according to claim 1, wherein the detection unit includes a first detection unit that detects a gluing position of the envelope based on the set type of the envelope.   The image forming apparatus according to claim 1, further comprising: a second detection unit that detects a pasting position of the envelope based on a thickness of the envelope. Further comprising image reading means for reading the image of the envelope,
The image forming apparatus according to claim 1, wherein the detection unit includes a third detection unit that detects a gluing position of the envelope based on an image read by the image reading unit. A control program for an image forming apparatus having a fixing device for fixing toner on an envelope produced by gluing a recording medium,
A detection step of detecting a gluing position of the envelope before fixing the toner on the envelope by the fixing device;
A control program for an image forming apparatus, which causes a computer to execute a control step of switching a fixing condition, which is a condition for fixing toner on the envelope by the fixing device, according to the gluing position.

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