JP2010128203A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus that sets the pressing force of a pressure roller on a fixing roller, which is suitable for the type of a recording sheet even when various recording sheets are used, thereby effectively preventing conveyance failure and fixing failure, such as displacement caused by wrinkle. <P>SOLUTION: The image forming apparatus D includes: a fixing device 12 configured so that a pressure contact state and a pressure contact release state may be switched by an automatic pressure contact releasing means 150; a control means 200; and an operating means 118. The automatic pressure contact releasing means 150 can change the pressing force of the pressure roller 130 on the fixing roller 120 in the pressure contact release state. Using the operating means 118, the control means 200 can change and input, in many stages, set information for the pressing force applied by the automatic pressure contact release means 150. In addition, the control means 200 controls the pressing force of the pressure roller 130 on the fixing roller 120 by the automatic pressure contact release means 150 on the basis of the input set information for the pressing force. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, and a printer.

  In an image forming apparatus, for example, when an electrophotographic method is adopted, an electrostatic latent image is formed on the surface of an image carrier such as a photosensitive drum, and the electrostatic latent image on the surface of the image carrier is developed with a developer. Thus, a toner image is formed on the surface of the image carrier, the toner image is transferred from the image carrier to a recording sheet such as paper, and the recording sheet is heated and pressurized to fix the toner image on the recording sheet. ing.

  The fixing of the toner image on the recording sheet is usually performed by a fixing device. As a fixing method used in the fixing device, a fixing method using a fixing roller and a pressure roller is widely used.

  In this fixing method, generally, a heat source heater is provided inside, and a fixing roller whose outer periphery is covered with rubber or resin having good releasability is pressed against a pressure roller, and formed between these rollers. Fixing is performed by passing a recording sheet on which a toner image is formed in the fixing nip region to heat and melt the toner and fusing the toner on the recording sheet. In such a fixing device, the fixing action can be surely performed by bringing the fixing roller and the pressure roller into pressure contact with each other.

  In such a fixing device, not only a fixing operation is performed on standard plain paper but also a fixing operation may be performed on a recording sheet such as an envelope or a cardboard. In this case, depending on the type of recording sheet (characteristics such as thickness and surface properties), the pressure applied to the pressure roller and the fixing roller may affect the state of the recording sheet when passing through the fixing nip region. . For example, when a fixing operation is performed on a recording sheet such as an envelope or thick paper, there is a risk of causing a conveyance failure such as a wrinkle or a fixing failure. Specifically, if the pressure applied between the pressure roller and the fixing roller is too large for the recording sheet passing between the fixing roller and the pressure roller, it causes a conveyance failure such as wrinkles. If the pressure applied to the fixing roller is too small, fixing failure is caused.

  From the viewpoint of avoiding such inconveniences, for example, Patent Document 1 below includes a mechanism for adjusting the pressure necessary for pressurization or the nip width between rollers with a bolt, and the two positions of pressurization and release are camped. In an image forming apparatus equipped with a fixing mechanism that can be selected by shape, several pressure heights are provided in the axial direction from the cam shaft center of the pressure cam, and the pressure cam is slid in the axial direction when released. There has been proposed an image forming apparatus configured to change the contact position and switch the pressure or the nip width between rollers in several stages.

  With the configuration described in Patent Document 1, it is possible to avoid the occurrence of poor conveyance and fixing failure of recording sheets such as envelopes and cardboard by switching the pressure required for pressurization or the nip width between rollers to several stages. Although it is possible to manually adjust the pressure or the nip width between the rollers for each type of recording sheet, the adjustment work becomes complicated, and the workability of the image forming work deteriorates accordingly.

In this regard, the following Patent Document 2 describes a pair of rotating bodies that are pressed against each other, a pressure changing means that can change the contact pressure of the pair of rotating bodies in a plurality of stages, and a rotation that rotates the pair of rotating bodies. A rotation means for detecting a rotation amount of the pair of rotating bodies, and a rotation driving means for rotating the pair of rotating bodies for a predetermined short period of time not reaching a steady speed, and for rotational driving during the predetermined short period of time; A pressurizing state determining unit that detects the amount of rotation of the pair of rotating bodies by the rotation amount detecting unit and determines the state of the mutual pressure of the pair of rotating bodies based on the detected amount of rotation; By automatically switching the pressing force between the pressure roller and the fixing roller in the plain paper printing mode and the pressing force between the pressure roller and the fixing roller in the envelope printing mode by the discrimination means, Etc. Pressurizing device has been proposed to prevent transmission failure.
JP 2004-77939 A JP 2004-198897 A

  However, in the configuration described in Patent Document 2, the pressure between the pressure roller and the fixing roller in the plain paper printing mode and the pressure between the pressure roller and the fixing roller in the envelope printing mode are automatically controlled. However, the pressing force between the fixing roller and the pressure roller suitable for various types of recording sheets (thickness, surface property, etc.) existing in the market is not set.

  Therefore, the present invention can set the pressure applied to the pressure roller and the fixing roller suitable for the type of the recording sheet even when various recording sheets are used. An object of the present invention is to provide an image forming apparatus capable of effectively preventing the occurrence of defects.

  In order to solve the above-described problems, the present invention is configured to press the pressure roller and the fixing roller by pressure contact means, and to release the pressure contact state and the pressure contact state between the pressure roller and the fixing roller by the pressure contact means. A fixing device configured to switch the pressure release state by the automatic pressure release unit, a control unit that performs operation control of the automatic pressure release unit, and an operation unit that can input setting information to the control unit, The automatic pressure release means can change the pressure applied to the pressure roller and the fixing roller in the pressure release state, and the control means can be changed by the automatic pressure release means by the operation means. The setting information of the pressure applied to the pressure roller and the fixing roller can be changed and input in multiple stages, and the pressure input by the operation means To provide an image forming apparatus and controls such pressure the pressure roller by the automatic pressure release means based on the setting information of the said fixing roller.

  The “pressure contact released state” in the present invention refers to a state in which the pressure applied to the pressure roller and the fixing roller is lower than the pressure applied in the pressure contact state by the pressure contact means. This is a concept including a state in which no pressure is applied between the fixing roller and a pressure is applied between the fixing roller and the pressure roller by the thickness of the recording sheet passing between the two rollers. .

  According to the image forming apparatus of the present invention, the control unit is configured to change the pressure applied to the pressure roller and the fixing roller in the pressure released state by the operation unit. The setting information of the pressure applied to the pressure roller and the fixing roller can be changed and input in multiple stages. Thereby, even when various recording sheets are used, it is possible to set the pressure applied to the pressure roller and the fixing roller suitable for the type of the recording sheet. Further, the control means controls the pressure applied to the pressure roller and the fixing roller by the automatic pressure release means based on the pressure setting information input by the operation means. As a result, it is possible to effectively prevent the occurrence of conveyance failure and fixing failure such as wrinkles.

  In the image forming apparatus according to the present invention, as a specific aspect of the setting information of the multi-stage pressing force between the pressure roller and the fixing roller, the multi-stage of the pressure roller with respect to the fixing roller in the pressure-release state The relative distance can be illustrated.

  In this case, the automatic pressure release means includes a cam mechanism for moving the pressure roller in the pressure contact direction and the pressure release direction with respect to the fixing roller, and the multi-stage relative distance is determined in the pressure release state. The aspect currently memorize | stored beforehand as a multistage operation time of the said cam mechanism can be illustrated.

  As a more specific aspect, the multi-step relative distance is stored in advance as an elapsed time obtained by adding the equal time for every equal time obtained by equally dividing the operation time of the cam mechanism in the pressure released state into multiple steps. Can be mentioned.

  In this specific matter, since the cam mechanism is used, the pressure contact state of the pressure roller with respect to the fixing roller can be easily realized, and the multi-step relative distance is equalized at every equal time. Since the elapsed time obtained by adding the minutes is stored in advance, the multi-step relative distance can be easily controlled with a simple control configuration.

  In the image forming apparatus according to the present invention, the setting information of the multi-stage pressing force between the pressure roller and the fixing roller corresponds to a predetermined multi-stage pressing force of the pressure roller with respect to the fixing roller. Are preferably stored in advance.

  In this specific matter, the multi-stage relative distance is stored in advance corresponding to the predetermined multi-stage pressurizing force of the pressure roller with respect to the fixing roller. It is possible to reliably correspond to a predetermined type of recording sheet.

  In the image forming apparatus according to the present invention, it is preferable that setting information for multi-stage pressurization between the pressure roller and the fixing roller can be arbitrarily stored.

  In this specific matter, since the multi-stage relative distance can be arbitrarily stored, the multi-stage relative distance can be surely associated with all types of recording sheets existing in the market.

  In the image forming apparatus according to the present invention, the setting information of the multi-stage pressing force between the pressure roller and the fixing roller is set corresponding to a plurality of types of recording sheets having different characteristics such as thickness and surface property. It is preferable.

  In this specific matter, the setting information of the multi-stage pressing force between the pressure roller and the fixing roller is set according to characteristics such as thickness and surface property of a plurality of types of recording sheets. Thus, it is possible to prevent the occurrence of conveyance failure and fixing failure.

  In such a configuration, the operation means is provided with a display means, and the control means displays a plurality of types of recording sheets in a selectable manner on the display means, and is displayed on the display means by the operation means. It is preferable that any one of a plurality of types of recording sheets can be selectively input.

  In this specific matter, the setting information of the pressing force between the pressure roller and the fixing roller corresponding to the recording sheet can be easily set by a simple input operation.

  As described above, according to the image forming apparatus of the present invention, it is possible to set the pressure applied to the pressure roller and the fixing roller suitable for the type of recording sheet even when various recording sheets are used. As a result, it is possible to effectively prevent the occurrence of conveyance failure and fixing failure such as wrinkles.

  Hereinafter, an embodiment according to the present invention will be described with reference to the drawings. In addition, the following embodiment is an example which actualized this invention, Comprising: The thing of the character which limits the technical scope of this invention is not.

[Entire configuration of image forming apparatus]
FIG. 1 is a schematic side view showing an image forming apparatus according to an embodiment of the present invention. An image forming apparatus D shown in FIG. 1 includes a document reading device B that reads an image of a document, and an image of the document read by the document reading device B or an image received from the outside in color or single color. And an apparatus main body A for recording and forming.

  In the document reader B, when the document is set on the document set tray 41, the pickup roller 44 is pressed against the surface of the document and rotated, the document is pulled out from the tray 41, and passes between the suction roller 45 and the separation pad 46. After being separated one by one, it is transported to the transport path 47.

  In the conveyance path 47, the leading edge of the document contacts the registration roller 49 and is aligned parallel to the registration roller 49, and then the document is conveyed by the registration roller 49 and passes between the reading guide 51 and the reading glass 52. At this time, the light of the light source of the first scanning unit 53 is irradiated on the surface of the document through the reading glass 52, and the reflected light is incident on the first scanning unit 53 through the reading glass 52. The image is reflected by the mirrors of the second scanning units 53 and 54 and guided to the imaging lens 55, and an image on the surface of the document is formed on a CCD (Charge Coupled Device) 56 by the imaging lens 55. The CCD 56 reads an image on the document surface and outputs image data indicating the image on the document surface. Further, the document is conveyed by the conveyance roller 57 and is discharged to the paper discharge tray 59 via the paper discharge roller 58.

  In addition, it is possible to read a document placed on the platen glass 61. The registration roller 49, the reading guide 51, the paper discharge tray 59, and the like and the members above them form an integrated cover body, and the document is scanned on one side (back side) in the main scanning direction of the document reading device B. It is pivotally supported so as to be openable and closable about an axis along the conveying direction. When the upper cover body is opened, the document table glass 61 is opened, and a document can be placed on the document table glass 61. When the document is placed and the cover body is closed, the first and second scanning units 53 and 54 are moved in the sub-scanning direction, and the first scanning unit 53 exposes the document surface on the document table glass 61. Reflected light from the document surface is guided to the imaging lens 55 by the first and second scanning units 53 and 54, and an image on the document surface is formed on the CCD 56 by the imaging lens 55. At this time, the first and second scanning units 53 and 54 are moved while maintaining a predetermined speed relationship with each other, and reflection of the document surface → first and second scanning units 53 and 54 → imaging lens 55 → CCD 56 is performed. The positional relationship between the first and second scanning units 53 and 54 is always maintained so that the length of the optical path of the light does not change, and thereby the focus of the image on the original surface on the CCD 56 is always accurately maintained.

  The entire image of the original read in this way is sent and received as image data to the apparatus main body A of the image forming apparatus D, and the apparatus main body A records the image on a recording sheet.

  On the other hand, the apparatus main body A of the image forming apparatus D includes an exposure apparatus 1, a developing apparatus 2 (2a, 2b, 2c, 2d), a photosensitive drum 3 (3a, 3b, 3c, 3d) acting as an image carrier, and charging. Intermediate transfer belt device 8 including a container 5 (5a, 5b, 5c, 5d), a cleaner device 4 (4a, 4b, 4c, 4d), and an intermediate transfer roller 6 (6a, 6b, 6c, 6d) acting as a transfer portion. A fixing device 12, a sheet conveying device 18, a paper feed tray 10 that functions as a paper feed unit, and a paper discharge tray 15 that functions as a paper discharge unit.

  The image data handled in the apparatus main body A of the image forming apparatus D is data corresponding to a color image using each color of black (K), cyan (C), magenta (M), yellow (Y), or a single color (for example, This corresponds to a monochrome image using (black). Accordingly, the developing device 2 (2a, 2b, 2c, 2d), the photosensitive drum 3 (3a, 3b, 3c, 3d), the charger 5 (5a, 5b, 5c, 5d), and the cleaner device 4 (4a, 4b, 4c, 4d) and four intermediate transfer rollers 6 (6a, 6b, 6c, 6d) are provided so as to form four types of images corresponding to the respective colors. Is associated with black, b with cyan, c with magenta, and d with yellow to form four image stations. Hereinafter, the description will be made with the suffixes a to d omitted.

  The photoconductor drum 3 is disposed at substantially the center in the vertical direction of the apparatus main body A.

  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 contact type roller type or brush type charger, a charger type charger is used. .

  Here, the exposure apparatus 1 is a laser scanning unit (LSU) provided with a laser diode and a reflection mirror, and exposes the surface of the charged photosensitive drum 3 according to image data, and according to the image data on the surface. An electrostatic latent image is formed.

  The developing device 2 develops the electrostatic latent image formed on the photosensitive drum 3 with (K, C, M, Y) toner. The cleaner device 4 removes and collects toner remaining on the surface of the photosensitive drum 3 after development and image transfer.

  In addition to the intermediate transfer roller 6, the intermediate transfer belt device 8 disposed above the photosensitive drum 3 includes an intermediate transfer belt 7, an intermediate transfer belt drive roller 21, a driven roller 22, a tension roller 23, and an intermediate transfer belt. A cleaning device 9 is provided.

  Roller members such as the intermediate transfer belt drive roller 21, the intermediate transfer roller 6, the driven roller 22, and the tension roller 23 stretch and support the intermediate transfer belt 7, and the intermediate transfer belt 7 is supported in a predetermined sheet conveyance direction (in the drawing). Move around in the direction of arrow C).

  The intermediate transfer roller 6 is rotatably supported inside the intermediate transfer belt 7 and is pressed against the photosensitive drum 3 via the intermediate transfer belt 7.

  The intermediate transfer belt 7 is provided so as to be in contact with each photoconductive drum 3, and a color toner image (each color is transferred by sequentially superimposing and transferring the toner image on the surface of each photoconductive drum 3 onto the intermediate transfer belt 7. Toner image). Here, the transfer belt 7 is formed in an endless belt shape using a film having a thickness of about 100 μm to 150 μm.

  The transfer of the toner image from the photosensitive drum 3 to the intermediate transfer belt 7 is performed by an intermediate transfer roller 6 that is in pressure contact with the inner side (back surface) of the intermediate transfer belt 7. A high voltage transfer bias (for example, a high voltage having a polarity (+) opposite to the toner charging polarity (−)) is applied to the intermediate transfer roller 6 in order to transfer the toner image. Here, the intermediate transfer roller 6 is a roller based on 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 recording paper.

  The apparatus main body A of the image forming apparatus D further includes a secondary transfer apparatus 11 including a transfer roller 11a that functions as a transfer unit. The transfer roller 11 a is in contact with the outside of the intermediate transfer belt 7.

  As described above, the toner images on the surfaces of the respective photosensitive drums 3 are stacked on the intermediate transfer belt 7 and become a color toner image indicated by the image data. The toner images of the respective colors stacked in this way are conveyed by the intermediate transfer belt 7 and transferred onto the recording paper by the secondary transfer device 11.

  The intermediate transfer belt 7 and the transfer roller 11a of the secondary transfer device 11 are pressed against each other to form a transfer nip region. The transfer roller 11a of the secondary transfer device 11 has a voltage (for example, a polarity (+) opposite to the toner charging polarity (-)) for transferring the toner image of each color on the intermediate transfer belt 7 onto a recording sheet. Is applied). Further, in order to constantly obtain the transfer nip area, either the transfer roller 11a of the secondary transfer device 11 or the intermediate transfer belt drive roller 21 is made of a hard material (metal or the like), and the other is made of a soft material such as an elastic roller. Material (elastic rubber roller, foaming resin roller, etc.) is used.

  In addition, the toner image on the intermediate transfer belt 7 may not be completely transferred onto the recording paper by the secondary transfer device 11, and the toner may remain on the intermediate transfer belt 7. Causes color mixing. Therefore, the residual toner is removed and collected by the intermediate transfer belt cleaning device 9. The intermediate transfer belt cleaning device 9 includes, for example, a cleaning blade that contacts the intermediate transfer belt 7 as a cleaning member, and residual toner can be removed and collected by the cleaning blade. The driven roller 22 supports the intermediate transfer belt 7 from the inside (back side), and the cleaning blade is in contact with the intermediate transfer belt 7 so as to press the driven roller 22 from the outside.

  The image forming unit 20 is composed of various image forming elements such as the exposure device 1, the developing device 2, the photosensitive drum 3, the cleaner device 4, the charger 5, and the transfer units 8 and 11.

  The paper feed tray 10 is a tray for storing recording paper, and is provided below the image forming unit 20 of the apparatus main body A. A paper discharge tray 15 provided on the upper side of the image forming unit 20 is a tray for placing printed recording paper face down.

  Further, the apparatus main body A is provided with a sheet conveying device 18 for sending the recording paper in the paper feed tray 10 to the paper discharge tray 15 via the secondary transfer device 11 and the fixing device 12. The sheet conveying device 18 has an S-shaped sheet conveying path S, and along the sheet conveying path S, a pickup roller 16, a roller roller 14a, a separation roller 14b, each conveying roller 13, a pre-registration roller 19, a resist Conveying members such as a roller 14, a fixing device 12 and a paper discharge roller 17 are arranged.

  The pickup roller 16 is a call-in roller that is provided at the downstream end of the sheet feeding tray 10 in the sheet conveying direction and supplies recording sheets from the sheet feeding tray 10 to the sheet conveying path S one by one. The separating roller 14a passes the recording paper between the separating roller 14b and conveys it to the sheet conveying path S while separating it one by one. Each conveyance roller 13 and the pre-registration roller 19 are small rollers for promoting and assisting the conveyance of the recording paper. Each conveying roller 13 is provided at a plurality of locations along the sheet conveying path S.

  In the stopped state, the registration roller 14 abuts the leading end of the recording sheet that has been conveyed, aligns the leading end of the recording sheet, and is intermediate in the transfer nip region between the intermediate transfer belt 7 and the secondary transfer device 11. In synchronization with the toner image formed on the intermediate transfer belt 7 so that the toner image on the transfer belt 7 is transferred to the recording paper, the recording paper is conveyed in a timely manner. For example, the registration roller 14 is arranged so that the toner image on the intermediate transfer belt 7 in the transfer nip area between the intermediate transfer belt 7 and the secondary transfer device 11 matches the position where the image on the recording paper is to be formed. Transport.

  The fixing device 12 receives the recording sheet on which the toner image has been transferred, and transports the recording sheet sandwiched between the fixing roller 120 and the pressure roller 130. The fixing device 12 will be described in detail later.

  The recording paper after the fixing of the toner images of the respective colors is discharged onto the paper discharge tray 15 by the paper discharge roller 17.

  It is also possible to form a monochrome image using only one of the four image forming stations and transfer the monochrome image to the intermediate transfer belt 7 of the intermediate transfer belt device 8. Similarly to the color image, this monochrome image is also transferred from the intermediate transfer belt 7 to the recording paper and fixed on the recording paper.

  In addition, in the case of forming not only the front (front) surface of the recording sheet but also both sides, the recording sheet is fixed on the surface of the recording sheet by the fixing device 12 and then the recording sheet is discharged on the sheet conveying path S by the sheet discharge roller 17. In the middle of the conveyance, the paper discharge roller 17 is stopped and then reversely rotated, the recording paper is passed through the reversing path Sr, the recording paper is turned upside down, and the recording paper is again guided to the registration rollers 14. Similarly to the front surface of the recording paper, an image is recorded and fixed on the back surface of the recording paper, and the recording paper is discharged to the paper discharge tray 15.

[Description of Features of the Present Invention]
The image forming apparatus D according to the embodiment of the present invention includes a fixing device 12, a control unit (an example of a control unit) 200, and an operation unit (an example of an operation unit) 118. Note that the control unit 200 and the operation unit 118 are shown in FIGS. 4 and 7B described later, respectively, and are not shown in FIG.

[Description of entire fixing device]
FIG. 2 is a side view illustrating a schematic configuration of the fixing device 12. As shown in FIG. 2, the fixing device 12 includes a fixing roller 120, a pressure roller 130, a pressure contact device (an example of a pressure contact unit) 140 for pressing the pressure roller 130 against the fixing roller 120, and a pressure contact device 140. An automatic pressure release device (an example of an automatic pressure release unit) 150 that automatically switches between a pressure contact state in which the pressure roller 130 is pressed against the fixing roller 120 and a pressure release state in which the pressure contact state is released.

  The fixing device 12 is a recording sheet on which an unfixed toner image that is a visible image is formed in a fixing nip region N that is a contact region between both rollers formed by pressing the pressure roller 130 against the fixing roller 120. P is passed and unfixed toner on the recording paper P is heated and melted and fixed on the recording paper P. The recording paper P is conveyed along the sheet conveyance path S from the bottom to the top in FIG. The fixing device 12 further includes a fixing device chassis 110 and a pressure roller holder 102 that swings around a pivot shaft along the roller axis direction with respect to the fixing device chassis 110. The fixing device chassis 110 is provided in front of the fixing roller 120 and the pressure roller 130, and is indicated by a virtual line in FIG.

[Fixing roller]
The fixing roller 120 is provided on the fixing device chassis 110 so as to be rotatable about its axis, and is driven to rotate by a driving source (not shown). Specifically, the fixing roller 120 has a roller shaft 124 attached to the fixing device chassis 110 so as to be rotatable about its axis, and driving from a driving motor (not shown) is transmitted via a driving transmission means. The recording paper P is rotated in the direction in which the recording paper P is conveyed (in the direction of arrow X1 in the figure).

  The fixing roller 120 includes a metal core 121, an elastic body layer 122 formed on the outer peripheral surface of the metal core 121, and a surface layer 123 formed on the outer peripheral surface of the elastic body layer 122. As the metal forming the core metal 121, a metal having high thermal conductivity can be used, and examples thereof include aluminum and iron. Examples of the shape of the cored bar 121 include a cylindrical shape and a columnar shape. From the viewpoint of reducing the amount of heat released from the cored bar 121, it is preferable to use a cylindrical shape.

  The material constituting the elastic layer 122 is not particularly limited as long as it has rubber elasticity, but it is preferable to use a material having excellent heat resistance. Specific examples of such materials include silicone rubber, fluorine rubber, fluorosilicone rubber, and the like. Among these, it is preferable to use silicone rubber that is particularly excellent in rubber elasticity.

  The material constituting the surface layer 123 is not particularly limited as long as it is excellent in heat resistance and durability and has a low adhesion to the toner. Examples of such materials include fluorine resin materials such as PFA (copolymer of tetrafluoroethylene and perfluoroalkyl vinyl ether) and PTFE (polytetrafluoroethylene), and fluorine rubber. In the present embodiment, the surface layer 123 is a PFA layer having a thickness of about 40 μm.

[Pressure roller]
The pressure roller 130 is provided on the pressure roller holder 102 so as to be rotatable about an axis. Specifically, the pressure roller 130 has a roller shaft 134 attached in the vicinity of the central portion of the pressure roller holder 102 so as to be rotatable about its axis. The pressure roller 130 is in contact with the rotationally driven fixing roller 120 and is rotated by this contact.

  The pressure roller 130 presses (presses) the toner in a molten state against the recording paper P when the fixing roller 120 heats and fixes the toner image onto the recording paper P, whereby the toner image is applied to the recording paper P. Promote the establishment of

  The pressure roller 130 includes a core bar 131, an elastic layer 132 formed on the outer peripheral surface of the core bar 131, and a surface layer 133 formed on the outer peripheral surface of the elastic layer 132. . As materials for forming the cored bar 131, the elastic body layer 132, and the surface layer 133, the same metals or materials as those for forming the cored bar 121, the elastic body layer 122, and the surface layer 123 of the fixing roller 120 can be used, respectively. . Further, the shape of the core bar 131 can be the same as that of the fixing roller 120.

[About heaters, etc.]
A heating heater can be provided at least inside the fixing roller 120 of the fixing roller 120 and the pressure roller 130. In the present embodiment, heating heaters (here, halogen heater lamps) 127 and 137 are provided inside both the fixing roller 120 and the pressure roller 130.

  Further, temperature detection units (for example, temperature sensors such as a thermistor) 125 and 135 (not shown in FIG. 2, refer to FIG. 4) are arranged on the outer peripheral surfaces of the fixing roller 120 and the pressure roller 130. The control unit 200 shown in FIG. 4 energizes the heating heaters 127 and 137 so that the surface temperatures of the fixing roller 120 and the pressure roller 130 are kept constant based on the measured values of the temperature detection units 125 and 135. Is controlled.

[About pressure welding equipment]
The pressure contact device 140 includes a pressure roller holder 102 and an urging member (here, a spring) 106. The pressure roller holder 102 supports the pressure roller 130 in a rotatable manner, while pressing in the pressure contact direction (X1 direction in the figure) and the pressure release direction (X2 direction in the figure) for releasing the pressure contact. The fixing device chassis 110 is pivotally supported so as to be rotatable about a pivot shaft along the roller axis direction. Here, in the pressure roller holder 102, the fixing roller 120 side is referred to as “inside”, and the side opposite to the fixing roller 120 side is referred to as “outside”.

  Specifically, the pressure roller holder 102 is provided with a holder support shaft 103 along the roller axis direction at a position below the pressure roller 130 of the pressure roller holder 102 and obliquely below and below the roller shaft 134. The holder support shaft 103 is rotatably attached to the fixing device chassis 110. Accordingly, the pressure roller 130 can swing in the pressure contact direction X1 and the pressure release direction X2 with the holder support shaft 103 as a fulcrum.

  The pressure roller holder 102 is urged in the pressure contact direction X1 by a spring 106 so that the pressure roller 130 is pressed against the fixing roller 120.

  Specifically, a holder upper surface 104 is formed inside the pressure roller holder 102 above the pressure roller 130. Further, the back surface of the holder upper surface 104 of the pressure roller holder 102 is in pressure contact with the tip of a spring 106 whose base end is fixed by a spring support piece 107 located outside the pressure roller holder 102. The spring support piece 107 is fixed to the fixing device chassis 110. As a result, the pressure roller holder 102 is urged toward the fixing roller 120, and the pressure roller 130 can be brought into a pressure contact state with the fixing roller 120. At this time, the pressure roller 130 is pressed against the fixing roller 120 with a predetermined first pressing force by the pressure contact device 140. The standard plain paper P passing through the fixing nip region N between the fixing roller 120 and the pressure roller 130 can be reliably fixed by the pressure contact of the pressure roller 130 to the fixing roller 120 by the pressure contact device 140. It can be done.

[Automatic pressure release device]
The automatic pressure release device 150 can change the pressure applied to the fixing roller 120 by the pressure roller 130 in the pressure release state of the pressure roller 130 with respect to the fixing roller 120. In the present embodiment, the automatic pressure release device 150 includes a cam mechanism that moves the pressure roller 130 in the pressure contact direction X1 and the pressure release direction X2 with respect to the fixing roller 120. By using the cam mechanism in this way, the pressure contact release state of the pressure roller 130 with respect to the fixing roller 120 can be easily realized. Here, the automatic pressure-contact releasing device 150 is configured so that the pressure applied to the fixing roller 120 by the pressure roller 130 gradually changes in the pressure-release state of the pressure roller 130 with respect to the fixing roller 120 (ie, the pressure roller 102 The pressure roller 130) supported by the roller holder 102 is moved.

  Specifically, the automatic pressure release device 150 includes a pressure contact control lever 111 that restricts the urging force of the pressure roller 130 to the fixing roller 120 in the pressure contact state by the pressure contact device 140, and a pressure contact that rotationally drives the pressure contact control lever 111. A release driving unit (not shown in FIG. 2, refer to FIG. 4) 117 and a sensor 116 that functions as a second pressurizing state detecting unit that detects a state of the second pressurizing force of the pressure roller 130 to the fixing roller 120 described later. And.

  The pressure contact control lever 111 is supported by the fixing device chassis 110 so as to be rotatable around a pivot shaft along the roller axis direction. More specifically, the press contact control lever 111 is provided close to the pressure roller holder 102 at a position diagonally above and inside the pressure roller holder 102. The pressure control lever 111 is provided with a lever shaft 112 along the roller axis direction. The lever shaft 112 is attached to the fixing device chassis 110 so as to be rotatable about the axis. Here, the press contact control lever 111 has a shape in which a plate piece is joined under the upper half of the sector shape.

  The lever shaft 112 is operatively connected (directly or indirectly via a drive transmission mechanism) to the output side of the pressure release drive unit 117. Here, the pressure contact release drive unit 117 is a pressure contact control lever drive motor, and the pressure contact control lever 111 is rotationally driven about the lever shaft 112 by a normal rotation or reverse rotation of the drive motor. Yes. In FIG. 2, an arrow X <b> 1 indicates a normal rotation direction in the rotation of the press contact control lever 111, and an arrow X <b> 2 indicates a reverse direction in the rotation of the press contact control lever 111.

  Then, the automatic pressure release device 150 rotates the pressure control lever 111 in the forward rotation direction X1 or the reverse rotation direction X2, so that the pressure roller 130 is released from the pressure roller 130 when the pressure roller 130 is pressed against the fixing roller 120. The pressure applied to can be changed.

  Specifically, the pressure contact control lever 111 is provided with a lever projection 114 at the end of the plate piece opposite to the sector-shaped portion 115 with the lever shaft 112 in between. When the lever protrusion 114 is not in contact with the holder upper surface 104 of the pressure roller holder 102, the pressure control lever 111 is in a pressure contact state with the fixing roller 120 of the pressure roller 130, and the lever protrusion 114 is in the pressure roller holder. When the roller 102 abuts on the holder upper surface 104 and rotates about the lever shaft 112 in the forward rotation direction X1 or the reverse rotation direction X2, the pressure roller 130 can be released from the pressure contact state with respect to the fixing roller 120. In addition, in FIG. 2, the press-contact state is shown.

  Here, the “pressure contact release state” is a state in which the pressing force (maximum pressure contact force) of the pressure roller 130 to the fixing roller 120 in the pressure contact state by the pressure contact device 140 is regulated, and the fixing roller of the pressure roller 130. The pressure applied to 120 is lower than the pressure applied in the pressure contact state (maximum pressure contact force), and the fixing roller 120 is not pressurized by the pressure roller 130, so This includes a state in which pressure is applied to the fixing roller 120 and the pressure roller 130 by the thickness of the recording paper P passing through the fixing nip region N. In the “pressure contact released state”, pressure is applied to the fixing roller 120 and the pressure roller 130 regardless of the passage of the recording paper P to the fixing nip area N between the fixing roller 120 and the pressure roller 130. It may include a state that is not.

  The distance (radius) r between the outer peripheral surface (sliding contact surface with the holder upper surface 104) 114a of the lever protrusion 114 and the rotation center of the press contact control lever 111 (axial center of the lever shaft 112) is the forward rotation direction. It is formed so as to gradually increase from the X1 downstream end 114a ′ toward the upstream end 114a ″.

  In such a configuration, the pressure contact control lever 111 rotates in the normal rotation direction X1 around the lever shaft 112, so that the sliding contact surface 114a of the lever projection 114 is in sliding contact with the holder upper surface 104 of the pressure roller holder 102. The pressure roller holder 102 can be pushed in the pressure release direction X2 in accordance with the amount of rotation in the forward rotation direction X1. As a result, the pressure applied to the fixing roller 120 by the pressure roller 130 can be gradually reduced in accordance with the amount of rotation of the pressure control lever 111 in the forward rotation direction X1.

  Further, when the pressure control lever 111 rotates around the lever shaft 112 in the reversing direction X2, the sliding contact surface 114a of the lever protrusion 114 is in sliding contact with the holder upper surface 104 of the pressure roller holder 102, and the reversing direction X2 thereof. The pressure roller device 102 can be allowed to rotate in the pressure contact direction X1 by the pressure contact device 140 according to the amount of rotation. As a result, the pressure applied by the pressure roller 130 to the fixing roller 120 can be gradually increased in the reverse direction X2 of the pressure control lever 111 according to the amount of rotation.

  The pressure control lever drive motor may be rotationally controlled so that the pressure control lever 11 rotates only in one direction of the forward rotation direction X1 or the reverse rotation direction X2. The shape of the pressure control lever in this case is a cam shape that allows the pressure control lever to be operated so as to be in the pressure-released state in half rotation and to be operated in the pressure-contact state in the remaining half rotation. It can be.

  The sensor 116 detects a predetermined second pressing force of the pressure roller 130 to the fixing roller 120 in the pressure release state.

  Specifically, the fan-shaped portion 115 of the press contact control lever 111 is formed as a sensor light reflecting piece. The sensor 116 is a reflection type photosensor including a light emitting element such as a light emitting diode and a light receiving element that receives the reflected light from the sensor light reflecting piece 115 of the light emitted from the light emitting element. As the sensor 116, a transmissive photo sensor, a proximity sensor, or the like can be used.

  The position of the sensor 116 is controlled by pressing after the sliding contact surface 114a of the lever projection 114 abuts on the holder upper surface 104 of the pressure roller holder 102 by the rotation of the pressing control lever 111 in the normal rotation direction X1. When the lever 111 is further rotated in the forward rotation direction X1 and the pressure roller 130 is pressed against the fixing roller 120 with the second pressure, the position shifts from the non-detection state to the detection state. More specifically, the position of the sensor 116 is determined when the pressure control lever 111 rotates in the forward rotation direction X1 and the pressure roller 130 presses against the fixing roller 120 with the second pressure (pressure). The position at which the sensor 116 receives the reflected light from the sensor light reflecting piece 115 of the light emitted from the light emitting element by the sensor 116 (when the roller 130 moves from the position at the first pressurizing force by a predetermined first pressure release distance). It is.

  FIG. 3 shows a state in which the fixing roller 120 is pressed by the pressure roller 130 with the second pressure in the fixing device 12 shown in FIG. In FIG. 3, reference numeral h <b> 1 indicates the first pressure contact releasing distance of the pressure roller 130 from the position (see the broken line α in the drawing) at the first pressure force.

[About control unit and operation unit]
FIG. 4 is a block diagram mainly showing components related to the control of the fixing function of the fixing device 12.

  As shown in FIG. 4, the control unit 200 is connected to the operation unit 118 and the automatic pressure contact release device 150. As will be described later, the control unit 200 is configured to receive predetermined setting information from the operation unit 118 and to control the operation of the automatic pressure release device 150 based on the setting information.

  The control unit 200 includes a processing device 200a such as a CPU (Central Processing Unit) and a storage unit 200b. The storage unit 200b stores various control programs and necessary functions, and includes storage means such as a ROM (Read Only Memory), a RAM (Random Access Memory), and a rewritable nonvolatile memory.

  The control unit 200 reads various control programs from the storage unit 200b by the CPU, and executes the read control program to control the fixing function and the variable operation of the pressure applied to the fixing roller 120 by the pressure roller 130. Control to make it happen.

  The control unit 200 may be configured not only to control the fixing device 12 but also to control the operation of the entire image forming apparatus of FIG. In that case, the control unit 200 is connected to the image forming unit 20 and can further perform process control related to image formation of the image forming unit 20.

  When the control unit 200 only controls the fixing device 12, it can control the fixing device 12 by communicating with a control unit that controls the operation of the entire image forming apparatus D. In the following description, it is assumed that the control unit 200 controls the operation of the entire image forming apparatus D.

  The sensor 116 of the automatic pressure release device 150 can transmit a second pressure detection signal to the control unit 200 so as to detect a state in which the fixing roller 120 is pressed by the pressure roller 130 with the second pressure. It is connected to the input system of the control unit 200.

  The pressure contact release drive unit 117 of the automatic pressure release device 150 has an input side connected to the output system of the control unit 200 and controls the rotation of the pressure control lever 111 based on an operation signal from the control unit 200. Yes.

  Here, the control unit 200 drives the press contact control lever 111 to rotate in the forward rotation direction X1 at a predetermined constant rotational speed by the press release release drive unit 117, and detects the second applied pressure state detection signal by the sensor 116. After a predetermined rotation time has elapsed (after the predetermined second pressure contact release distance of the pressure roller 130), the fixing roller 120 is pressed by the pressure roller 130 with a third pressure smaller than the second pressure. It is designed to rotate to the position.

  FIG. 5 shows a state in which the fixing roller 120 is pressed by the pressure roller 130 with a third pressing force smaller than the second pressing force in the fixing device 12 shown in FIG. In FIG. 5, symbol h <b> 2 indicates the second pressure release distance of the pressure roller 130 from the position (see the broken line β in the figure) at the second pressure force.

  As shown in FIG. 4, the operation unit 118 is provided with a display unit (an example of a display unit) 119 such as a display device. The display unit 119 is connected to the output system of the control unit 200, and can output and display a display screen for displaying an operation instruction or a message by an operator such as a user or a serviceman by an output signal from the control unit 200. It is like that. The operation unit 118 includes an operation member such as an operation key so that an operation instruction by a user can be input to the control unit 200.

  When the standard plain paper is used as the recording paper P, the control unit 200 fixes the standard fixing mode in which an unfixed toner image is fixed on the recording paper P, and when a special sheet such as an envelope or thick paper is used as the recording paper P. And a special fixing mode for fixing an unfixed toner image on the recording paper P.

  In the normal fixing mode, the control unit 200 allows the recording paper P to pass through the fixing nip area N between the fixing roller 120 and the pressure roller 130 with the first pressure, while in the special fixing mode, the recording paper P P is applied to a fixing nip region N between the fixing roller 120 and the pressure roller 130 in a multi-stage n (n is an integer of 2 or more) determined between the second pressing force and the third pressing force. It is made to pass with any pressure among the pressures.

  The control unit 200 can be configured to change and input the setting information of the pressure applied to the fixing roller 120 of the pressure roller 130 by the automatic pressure contact release device 150 in the special fixing mode by the operation unit 118 in multiple stages n. Has been.

  In the present embodiment, the setting information of the multi-stage n pressure applied to the fixing roller 120 of the pressure roller 130 is stored in advance in the storage unit 200b, and the multi-stage n stored in the storage unit 200b. The pressure setting information can be selected and input by the operation unit 118.

  FIG. 6 is a diagram illustrating a memory table M1 of the storage unit 200b in which setting information of multi-stage n pressures is stored in advance. It should be noted that the setting information of the multi-stage n (here, eight stages) pressure is stored in advance in association with a plurality of setting numbers (here, setting numbers 1 to 8).

  In the present embodiment, the setting information of the multi-stage n pressure applied to the fixing roller 120 of the pressure roller 130 is the relative distance (roller shaft) of the multi-stage n of the pressure roller 130 with respect to the fixing roller 120 in the pressure release state. Distance). The relative distance of the multistage n is stored in advance in the storage unit 200b as the operation time of the multistage n of the cam mechanism in the pressure released state. Here, the setting information of the multi-stage n pressure applied to the fixing roller 120 by the pressure roller 130 is the predetermined rotation time (the pressure roller 130 after the second pressure state detection signal is detected by the sensor 116. Of the pressure contact control lever 111 in the normal rotation direction X1 (the travel distance of the pressure roller 130).

  Specifically, the relative distance of the multi-stage n is previously stored in the storage unit 200b as an elapsed time obtained by adding the equal time for every equal time obtained by equally dividing the operation time of the cam mechanism in the pressure released state into multi-stages. It is remembered. In this way, the multi-step relative distance can be easily controlled with a simple control configuration. Here, the setting number 1 is the rotation time corresponding to the second pressing force of the pressure roller 130 with respect to the fixing roller 120 (when the second pressing force state detection signal is detected (that is, 0 second)). Is a predetermined rotation time (here, g seconds) corresponding to the third pressing force of the pressure roller 130 with respect to the fixing roller 120. The other setting numbers 2 to [n-1] (here, setting numbers 2 to 7) are the predetermined rotation time (here, the pressure contact control lever 111 from the time when the sensor 116 detects the second pressure state detection signal). In this case, the elapsed time (here, a second to f second) is obtained by adding the equal time to every equal time obtained by dividing [n-1] into equal parts (here, seven equal parts). For example, if n is 8 and the predetermined rotation time g seconds is 0.7 seconds, the equal time is 0.1 seconds, and a seconds to f seconds are 0.1 seconds and 0.2 seconds, respectively. 0.3 seconds, 0.4 seconds, 0.5 seconds, and 0.6 seconds.

  Thereby, in setting number 1, the pressure roller 130 can be pressed against the fixing roller 120 with the second pressure when the sensor 116 detects the second pressure state detection signal. In the case of number n (here, setting number 8), the pressure roller with the third pressure after the predetermined rotation time (here, g seconds) has elapsed since the sensor 116 detected the second pressure state detection signal. The pressure operation to 130 fixing rollers 120 can be performed. Further, in setting numbers 2 to [n-1] (here, setting numbers 2 to 7), the elapsed time (here, a second) from the time when the sensor 116 detects the second pressure state detection signal. The pressing operation of the pressure roller 130 to the fixing roller 120 can be performed with the applied pressure later.

  The multi-step relative distance may be stored in advance in the storage unit 200b corresponding to the multi-step pressurization force determined in advance of the pressure roller 130 with respect to the fixing roller 120. By doing so, it is possible to reliably correspond the multi-stage relative distance to a predetermined type of recording paper P existing in the market. Specifically, the rotation time (movement distance of the pressure roller 130) of the pressure contact control lever 111 after detecting the second pressure application state detection signal by the sensor 116 is determined by the pressure roller 130 relative to the fixing roller 120. It can be set corresponding to a multi-stage pressurizing force determined in advance. The multi-step relative distance may be arbitrarily stored in the storage unit 200b and rewritten. By doing so, the multi-step relative distance can be surely made to correspond to all types of recording paper P existing in the market. Specifically, the rotation time (movement distance of the pressure roller 130) of the pressure contact control lever 111 after the sensor 116 detects the second applied pressure state detection signal is set as the predetermined rotation time (pressure roller). It can be arbitrarily set by an operator (for example, a service person) within 130 (second pressure contact release distance).

  In the present embodiment, the setting information of the multi-stage n pressure applied to the fixing roller 120 of the pressure roller 130 is a record of a plurality of types m (m is an integer of 2 or more) having different characteristics such as thickness and surface property. The pressure setting information corresponding to the paper P is used.

  Specifically, the setting information of the multi-stage n pressing force is stored in advance in the storage unit 200b corresponding to a plurality of types of m recording sheets (envelopes here) P. Then, the control unit 200 can select and input any one of the plural types of recording paper P by the operation unit 118, and sets the setting information of the pressurizing force corresponding to the selected and input recording paper P. It is supposed to be.

  FIG. 7 is a diagram for explaining setting of the setting information of the pressurizing force corresponding to a plurality of types of recording paper P. FIG. 7A is a diagram illustrating a memory table M2 of the storage unit 200b in which multi-stage n pressure setting information is stored in advance corresponding to a plurality of types of recording paper P. FIG. FIG. 7B is a plan view showing a setting screen when a plurality of types m of recording sheets P are selectively input to the control unit 200 in the operation unit 118. In FIG. 7A, square type 2 is illustrated as the type of large-sized envelope, and long type 3 is illustrated as the type of small-sized envelope, and illustration of other envelope types is omitted. is doing.

  In the present embodiment, the control unit 200 displays a plurality of types of m recording sheets P on the display unit 119 so as to be selectable, and among the plurality of types of m recording sheets P displayed on the display unit 119 by the operation unit 118. Either can be selected and input. More specifically, a touch panel type input device is provided on the display unit 119 as an example of a part of the operation unit 118, and the control unit 200 is touched by a touch operation on a setting screen displayed on the display unit 119. Selection input is made.

In the setting screen shown in FIG. 7 (b), for example, if those having a basis weight of 85 g / mm ² is selected as an envelope for No. 2 square (see shaded in the figure), a memory table shown in FIG. 7 (a) By referring to M2, it is possible to read the setting number 4 corresponding to a square No. 2 envelope having a basis weight of 85 g / mm ² (see the shaded area in the figure). Furthermore, by referring to the memory table M1 shown in FIG. 6, the rotation time c seconds (movement distance of the pressure roller 130) of the press contact control lever 111 corresponding to the setting number 3 can be read.

  In the special fixing mode, the control unit 200 controls the pressure applied to the fixing roller 120 of the pressure roller 130 by the automatic pressure release device 150 based on the pressure setting information input from the operation unit 118. It is configured.

For example, when the envelope having the basis weight of 85 g / mm ² is selected as the square No. 2 envelope, the control unit 200 press-contacts in the forward rotation direction X1 from the time when the sensor 116 detects the second applied pressure state detection signal. The control lever 111 is stopped after being rotated for c seconds. The pressure roller 130 is pressed against the fixing roller 120 with the applied pressure when the operation is stopped. The control unit 200 can operate similarly when another envelope is selected. In the normal fixing mode, the control unit 200 causes the sensor 116 to emit light by the pressure contact state by the pressure contact device 140 (specifically, the pressure contact control lever 111 is rotated in the reverse direction X2 by the pressure contact release drive unit 117). The light applied to the fixing roller 120 by the pressure roller 130 is changed to the first pressure applied by the pressure contact device 140 by setting the light emitted from the element to the light reflected by the sensor light reflecting piece 115. It is said.

  According to the image forming apparatus D described above, the setting information on the pressure applied to the fixing roller 120 of the pressure roller 130 by the automatic pressure release device 150 can be changed and input in multiple stages n by the operation unit 118. The pressure applied to the fixing roller 120 by the pressure roller 130 suitable for the type m of the recording paper (envelope in this case) P can be set. In the special fixing mode, the pressure applied to the fixing roller 120 of the pressure roller 130 by the automatic pressure contact release device 150 is controlled based on the pressure setting information input from the operation unit 118. It is possible to effectively prevent the occurrence of conveyance failure and fixing failure.

  Furthermore, since the setting information of the multi-stage n pressure applied to the fixing roller 120 of the pressure roller 130 is set according to the characteristics such as the thickness and surface property of a plurality of types of recording paper P, the wrinkles are surely reduced. Thus, it is possible to prevent the occurrence of conveyance failure and fixing failure.

  In addition, a plurality of types of m recording sheets P are displayed on the display unit 119 so as to be selectable, and any one of the plurality of types m of recording sheets P displayed on the display unit 119 can be selected and input by the operation unit 118. Therefore, it is possible to easily set the setting information of the pressure applied to the fixing roller 120 of the pressure roller 130 corresponding to the recording paper P by a simple input operation by an operator such as a user or a serviceman.

1 is a schematic side view showing an image forming apparatus according to an embodiment of the present invention. FIG. 2 is a side view illustrating a schematic configuration of a fixing device. FIG. 3 is a side view showing a state in which the fixing roller is pressed with a second pressing force by a pressure roller in the fixing device shown in FIG. 2. FIG. 3 is a block diagram illustrating mainly components related to control of a fixing function of a fixing device. FIG. 3 is a side view showing a state in which the fixing roller is pressed by a pressure roller with a third pressing force smaller than the second pressing force in the fixing device shown in FIG. 2. It is a figure which shows the memory table of the memory | storage part by which the setting information of the multistage pressurizing force is stored beforehand. FIG. 4A is a diagram for explaining setting of pressurizing force setting information corresponding to a plurality of types of recording papers, and FIG. 9A illustrates in advance that multistage pressurizing force setting information corresponds to a plurality of types of recording papers. FIG. 4B is a plan view showing a setting screen when a plurality of types of recording sheets are selectively input to the control unit in the operation unit.

Explanation of symbols

12 Fixing device 102 Pressure roller holder 103 Holder support shaft 104 Holder upper surface 106 Spring (an example of an urging member)
107 Spring support piece 110 Fixing device chassis 111 Pressure contact control lever 112 Lever shaft 114 Lever protrusion 116 Sensor (an example of second pressurizing state detection means)
117 Pressure contact release drive unit 118 Operation unit (an example of operation means)
119 Display unit (an example of display means)
120 fixing roller 121 core metal 122 elastic layer 123 surface layer 124 roller shaft 127 heating heater 130 pressure roller 131 core metal 132 elastic body layer 133 surface layer 134 roller shaft 137 heating heater 140 pressure contact device (an example of pressure contact means)
150 Automatic pressure release device (an example of automatic pressure release means)
200 Control unit (an example of control means)
D Image forming apparatus N Fixing nip area P Recording paper (an example of a recording sheet)
X1 Pressure direction X2 Pressure release direction

Claims (8)

The pressure roller and the fixing roller are brought into pressure contact with the pressure contact means, and the pressure contact state between the pressure roller and the fixing roller by the pressure contact means and the pressure release state for releasing the pressure contact state are switched by the automatic pressure release means. A configured fixing device; and
Control means for controlling the operation of the automatic pressure release means;
Operation means capable of inputting setting information to the control means,
The automatic pressure release means can change the pressure applied to the pressure roller and the fixing roller in the pressure release state,
The control means is capable of changing and inputting the setting information of the pressure applied to the pressure roller and the fixing roller by the automatic pressure release means in multiple stages by the operation means, and the operation means An image forming apparatus, wherein the pressure applied to the pressure roller and the fixing roller by the automatic pressure release unit is controlled based on the input pressure setting information. The image forming apparatus according to claim 1,
The image forming apparatus according to claim 1, wherein the setting information of the multi-stage pressing force between the pressure roller and the fixing roller is a multi-stage relative distance of the pressure roller to the fixing roller in the pressure release state. The image forming apparatus according to claim 2.
The automatic pressure release unit includes a cam mechanism for moving the pressure roller in the pressure contact direction and the pressure release direction with respect to the fixing roller,
The multi-stage relative distance is stored in advance as a multi-stage operation time of the cam mechanism in the pressure released state. The image forming apparatus according to claim 3.
The multi-stage relative distance is stored in advance as an elapsed time obtained by adding the equally divided time for every equally divided time obtained by equally dividing the operation time of the cam mechanism in the pressure released state into multi-stages. Image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The setting information of the multi-stage pressing force between the pressure roller and the fixing roller is stored in advance corresponding to the predetermined multi-step pressing force of the pressure roller with respect to the fixing roller. An image forming apparatus. The image forming apparatus according to any one of claims 1 to 3,
The image forming apparatus, wherein the setting information of the multi-stage pressing force between the pressure roller and the fixing roller can be arbitrarily stored. The image forming apparatus according to any one of claims 1 to 6,
The setting information of multi-stage pressing force between the pressure roller and the fixing roller is set corresponding to a plurality of types of recording sheets having different characteristics such as thickness and surface property. . The image forming apparatus according to claim 7.
The operation means is provided with a display means,
The control means displays a plurality of types of recording sheets on the display means so as to be selectable, and the operation means can select and input any of the plurality of types of recording sheets displayed on the display means. An image forming apparatus.

Images