JP5142027B2 - Image fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to an image fixing device and an image forming apparatus.

  2. Description of the Related Art An image forming apparatus that forms a toner image on an image forming medium and fixes the toner image is known. The toner image is fixed by solidifying the toner by applying heat and pressure. As a technique for performing this fixing, for example, a technique described in Patent Document 1 is known.

Japanese Patent No. 3155862 (Claims)

  As the image forming medium used in the image forming apparatus, in addition to plain paper, a relatively thick or multiple layered material such as an envelope may be employed. Since plain paper and envelopes have different thicknesses, it is not preferable to use the same fixing conditions. For example, if the toner image is fixed under the condition of plain paper, the envelope may be wrinkled when the toner image is fixed to the envelope. Conversely, if an appropriate fixing condition for the envelope is selected, the image forming speed required for plain paper cannot be obtained. SUMMARY An advantage of some aspects of the invention is that it provides a technique capable of changing fixing conditions according to the type of image forming medium.

  According to the first aspect of the present invention, a pressurizing unit including a plurality of pressurizing units having different hardnesses, a first support member that supports the pressurizing unit, and the first support member are rotatable. A second support member that supports the second support member in a state, a base member that supports the second support member in a rotatable state, a counter means that faces the pressurizing means and is disposed on the base member, and is rotatable. An image fixing device including a cam member that is arranged in such a manner that the cam member is coupled to the first support member and pushes the second support member in a direction in which the pressurizing unit moves away from the facing unit. It is.

  According to a second aspect of the present invention, in the first aspect of the present invention, the cam member includes a first side, a second side that is farther from the rotation center of the cam member than the first side, and the first side. In the state where the first support member is coupled to the third support side on the third side of the rotation center, and the first side faces the second support member. The toner image is fixed to the image forming medium, and the toner image is fixed to the second image forming medium in a state where the second side is in contact with the second support member. .

According to a third aspect of the present invention, in the second aspect of the present invention, the pressurizing unit includes a first member and a second member that is softer than the first member, and the first side is In the state facing the second support member, the first member and the second member apply pressure to the first image forming medium between the opposing means and the second side is the second support. in a state of being in contact with the member, the first member is not applying pressure to the second image forming medium, the second member, the pressure to the second image forming medium between the countermeasure It is characterized by adding.

  According to a fourth aspect of the present invention, in the invention according to the second or third aspect, the fixing process of the toner image to the first image forming medium is performed by the third side contacting the second supporting member. The distance between the facing unit and the pressurizing unit is longer than that in the state in which the toner image is fixed on the second image forming medium.

  The invention according to claim 5 is the invention according to any one of claims 2 to 4, wherein the cam member has an elliptical shape, the first side is located on the minor axis, and the length of the cam member is long. The second side and the third side are located on the axis, and the second side and the third side are at a position sandwiching the rotation center of the cam member.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, further comprising pressure generating means for applying a pressure to push the second support member toward the cam member. To do.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the first support member and the cam member are coupled by a coil spring.

  The invention according to claim 8 is the invention according to any one of claims 1 to 6, wherein the coupling between the first support member and the cam member is movable to the first support member and rotates. It is characterized in that it is carried out by a coupling member supported in a free state and supported in a rotatable state by a cam member.

  According to a ninth aspect of the present invention, there is provided an image forming apparatus comprising: a toner image forming unit that forms a toner image; and the image fixing device according to any one of the first to eighth aspects. .

  According to the first aspect of the present invention, when the cam member rotates, the first support member coupled to the cam member rotates with respect to the second support member and is simultaneously pushed by the cam member. Two support members rotate relative to the base member. By these two rotations, the direction of the pressing unit with respect to the opposing unit changes, and the pressing state of the pressing unit with respect to the image forming medium conveyed between the pressing unit and the opposing unit changes. As a result, an image fixing apparatus in which the fixing conditions are changed according to the type of the image forming medium is provided.

  According to the second aspect of the present invention, by selecting the rotational position of the cam so that one of the three sides provided on the cam member faces the second support member, two types of image forming media can be obtained. There is provided an image fixing apparatus capable of selecting a fixing condition suitable for any of them.

  According to the invention described in claim 3, a relatively hard member and a relatively soft member are prepared as the pressurizing member, and when both are used for pressurization, only a relatively soft member is provided. There is provided an image fixing device in which the case where pressure is applied by using the cam member is determined by selecting the side of the cam member.

  According to the fourth aspect of the present invention, there is provided an image fixing apparatus in which the opposing means is separated from the pressurizing means than during the fixing process, and the jammed image forming medium can be removed.

  According to the fifth aspect of the present invention, there is provided an image fixing device in which each side of the present invention is configured according to any one of the second to fourth aspects by utilizing the elliptical shape of the cam member. .

  According to the sixth aspect of the present invention, the pressure applied from the pressure generating means to the second support member is changed by the rotation of the cam member, thereby changing the pressure applied from the pressure device toward the opposing means.

  According to the seventh aspect of the present invention, there is provided an image fixing device in which the movement of the cam member is transmitted to the first support member using the elasticity of the coil spring, and the pressure state of the pressure member is adjusted. The

  According to the eighth aspect of the present invention, there is provided an image fixing device in which the movement of the cam member is transmitted to the first support member using the coupling member, and the pressure state of the pressure member is adjusted. .

  According to the ninth aspect of the present invention, there is provided an image forming apparatus including the image fixing apparatus having the configuration according to any one of the first to eighth aspects.

(1) First Embodiment (Outline of Image Fixing Device)
First, an example of a configuration in which the cam and the first support member are coupled by a coil spring will be described. FIG. 1 is a conceptual diagram showing an example of an image fixing apparatus using the present invention. FIG. 1 shows an image fixing device 100. The image fixing device 100 includes a pressure device 123 that is an example of a pressure unit. The pressure device 123 includes two pressure units. One of the pressurizing units is a pad member 123a, and the other is a head member 123b. The pad member 123a is made of silicone rubber, and the head member 123b is made of a resin material harder than silicone rubber. That is, the pad member 123a is made of a softer material than the head member 123b.

  The pressurizing device 123 is fixed to the cylindrical member 101, and the cylindrical member 101 is fixed to the first support member 103. That is, the pressure device 123 is supported by the first support member 103. The cylindrical surface of the cylindrical member 101 is covered with a closed belt 102. The belt 102 is made of a fluororesin film and slides and rotates with respect to the cylindrical member 101. The pad member 123 a and / or the head member 123 b apply pressure to an image forming medium (not shown) sandwiched between the heating roll 111 and the belt 102 via the belt 102.

  The first support member 103 is supported by the second support member 104 in a rotatable state. Reference numeral 105 denotes a rotation shaft of the first support member 103, and the first support member 103 rotates relative to the second support member 104 about the rotation shaft 105. The second support member 104 is rotatably supported by a base member 106 fixed to a skeleton structure that is a base of the image fixing device 100. Reference numeral 107 denotes a rotation shaft of the second support member 104, and the second support member 104 rotates relative to the base member 106 around the rotation shaft 107.

  Reference numeral 111 denotes a heating roll which is an example of a countermeasure unit facing the pressure device 123. The heating roll 111 incorporates a heater inside and is rotated with respect to the base member 106 by a motor (not shown). The image forming medium onto which the toner image has been transferred is sandwiched between the heating roll 111 and the belt 102 and is conveyed upward from the lower side of the drawing by the rotation of the heating roll 111 while receiving pressure from the pressure device 123. . At this time, the toner constituting the toner image is fixed on the image forming medium by heat and pressure, and the image is formed.

  A cam 108 is fixed to the base member 106 so as to be rotatable on a rotation shaft 109. The cam 108 may not be directly fixed to the base member 106 so as to be freely rotatable, but may be rotatably fixed to another member fixed to the base member 106. The cam 108 has an elliptical shape centered on the position of the rotation shaft 109. In the present embodiment, an elliptical cam 108 is used for explanation, but any shape may be selected as long as it has a plurality of surfaces with different distances from the cam rotation shaft to the outer peripheral surface of the cam. . In FIG. 1, the right side of the cam 108 is the first side, the upper side is the second side, and the lower side is the third side. The cam 108 has a structure that can be rotated by a rotation mechanism (not shown). As the rotation mechanism, means selected from a handle, a lever, a motor, an electromagnetic solenoid, and the like are appropriately employed. One end of a coil spring 112 is fixed to a portion 110 near one end of the long axis direction of the cam 108. The other end of the coil spring 112 is fixed at a position away from the rotation shaft 105 of the first support member 103. That is, the first support member 103 and the cam 108 are coupled by the coil spring 112.

  A contact portion 113 is provided at the other end portion of the second support member 104 away from the rotation shaft 107, and one end of the coil spring 114 is in contact with the opposite portion that does not face the cam 108. The other end of the coil spring 114 is fixed to a coil spring support member 115 fixed to the skeleton structure of the apparatus to which the base member 106 is fixed. The coil spring 114 is an example of a pressure generating unit, and generates a pressure that pushes the second support member 104 in the direction of the cam 108. Reference numeral 116 denotes a stopper provided on the second support member that prevents the first support member 103 from rotating counterclockwise from the position shown in FIG.

  Next, the function of the pressurizing device 123 will be described. FIG. 7 is a conceptual diagram showing a state of pressure applied to the image forming medium by the pressurizing device 123. In FIG. 7, the description of the belt 102 and the image forming medium shown in FIG. 1 is omitted. When pressure is applied by the pad member 123a and the head member 123b, as shown in FIG. 7B, the pressure exerted by the head member 123b is greater than the pressure exerted by the pad member 123a. When pressure is applied only with the pad member 123a, the pressure applied to the heating roll 111 is smaller than the pressure when pressure is applied with the pad member 123a and the head member 123b, as shown in FIG.

  The pressurized state shown in FIG. 7A is suitable for an image forming medium in which wrinkles easily occur when a large pressure is applied to a narrow region such as an envelope. In this case, the pressure peak is low, and the pressure per unit area is reduced because the pad member 123a is deformed to disperse the pressure over a wide area. For this reason, the generation of wrinkles at the time of fixing processing in an image forming medium such as an envelope which is likely to generate wrinkles is prevented. Note that the pressurized state in FIG. 7A is not suitable when the image forming medium is conveyed at high speed because the pressure is weakened.

  The pressurized state shown in FIG. 7B is suitable when plain paper (paper used in normal printing) is used as an image forming medium. In this case, the image forming medium is conveyed from left to right in the drawing. At this time, a predetermined portion of the image forming medium first receives pressure from the pad member 123a and then receives pressure from the head member 123b. Since the pad member 123a is relatively soft and the head member 123b is relatively hard, the pressure distribution in the transport direction has a peak on the right side and a gentle mountain shape on the left side, as shown.

  Hereinafter, the operation resulting from such pressure distribution will be described. That is, when attention is paid to a predetermined portion of an unfixed toner image, the portion is first subjected to pressure by the pad member 123a and then more strongly applied by the head member 123b. At this time, a relatively long time of pressure from the soft pad member 123a secures a toner solidifying time and promotes toner fixing. After that, a pressure having a large peak value is received from the head member 123b for a relatively short time, so that the fixing of the toner is surely finished and the fixing of the unfixed toner is promoted. For this reason, the toner is surely fixed even if the conveyance speed of the image forming medium is high. In addition, since the fixing property of the toner can be improved and the unfixed components can be reduced, the heating roll 111 and the conveyance system can be wound around, and the separation from the members is not separated (the member is not separated from the member due to the influence of the toner fixing component. (Sticking phenomenon) is suppressed.

(Plain paper printing mode)
According to the structure shown in FIG. 1, the function of the pressurizing device 123 is selected by rotating the cam 108. First, a plain paper mode suitable for a case where plain paper (usually used printing paper) is used as a print medium as a print medium will be described. In this case, by rotating the cam 108, as shown in FIG. 1, the major axis of the cam 108 coincides with the Y-axis direction, the fixed portion 110 of the coil spring 112 is on the lower side, and the minor axis of the cam 108 It is assumed that the side on the side faces the contact portion 113. In this state, the coil spring 112 is extended from the no-load state, and the coil spring 114 is compressed from the no-load state.

  In this state, due to the elasticity of the coil spring 112, the first support member 103 is pulled obliquely upward to the left in the drawing. For this reason, the first support member 103 generates a force to rotate clockwise with respect to the second support member 104 about the rotation shaft 105. On the other hand, the contact portion 113 of the second support member 104 is pushed in the direction of the cam 108 by the repulsive force of the coil spring 114, so that the second support member 104 rotates counterclockwise about the rotation shaft 107. try to.

  The pressurizing device 123 is pushed in the direction of the heating roll 111 by the two rotations having different directions. In this state, when the heating roll 111 generates a force that rotates counterclockwise and the printing paper is conveyed from the lower side of the figure, the printing paper is sandwiched between the belt 102 and the heating roll 111, and the heating roll The printing paper moves upward according to the rotation of 111. At this time, the belt 102 rotates clockwise due to friction.

  When the printing paper is sandwiched between the belt 102 and the heating roll 111, the printing paper is heated from the heating roll 111. At this time, the back side of the belt 111 is pushed by the pressure device 123 by the mechanism described above, and pressure is applied to the printing paper. The toner image is fixed by heat and pressure.

  In the state shown in FIG. 1, the above-described generation of force due to the clockwise rotation about the rotation shaft 105 of the first support member 103 and the reaction with the rotation shaft 107 of the second support member 104 as the axis. Due to the generation of force due to the clockwise rotation, pressure is applied to the printing paper from both the pad member 123a and the head member 123b of the pressure device 123. That is, pressure is applied in the state shown in FIG. Thus, fixing suitable for plain paper is performed by the rotational position of the cam 108.

(Envelope printing mode)
Next, an envelope printing mode in which fixing suitable for the case of using an envelope as an image forming medium will be described. In this case, in the state shown in FIG. 1, the cam 108 is rotated 90 ° clockwise to obtain the state shown in FIG. FIG. 2 shows a state in which the cam 108 is rotated 90 ° clockwise from FIG.

  In this case, the contact portion 113 is pushed rightward in the drawing by one of the sides of the cam 108 in the long axis direction. Therefore, the second support member 104 rotates clockwise about the rotation shaft 107 from the state shown in FIG. By this rotation, the pressure device 123 moves in a direction away from the heating roll 111, and the head member 123 b moves away from the heating roll 111 and moves so that the pad member 123 a faces the heating roll 111. As a result, the head member and the pad member move away from the heating roll.

  In addition, the side of the portion 110 side where the coil spring 112 is fixed in the longitudinal direction of the cam 108 is further away from the first support member 103 than in the case of FIG. 1, and the coil spring 112 extends. For this reason, the first support member 103 rotates clockwise about the rotation shaft 105. By this rotation, the pad member 123a moves so as to face obliquely upward to the left, and the head member 123b moves away from the heating roll 111. As a result, the pad member approaches the heating roll, and the pressurizing region is formed only by the pad member 123a.

  In this way, the state shown in FIG. 2 is obtained. In this state, pressurization in the direction of the heating roll 111 is not performed by the head member 123b but only by the pad member 123a. Further, when the side of the long axis direction of the cam 108 contacts the contact portion 113, the second support member 104 can no longer rotate counterclockwise, and the pressurizing device is further pressed by the coil spring 114 from the state of FIG. 123 is not pushed in the direction of the heating roll 111. For this reason, the source of pressure applied from the heating device 123 to the heating roll 111 is only the coil spring 112, and the pressure applied by the heating device 123 in the direction of the heating roll 111 is smaller than that in the plain paper mode of FIG. . In this way, the pressure distribution shown in FIG. 7A is obtained.

  In this state, the heating roll 111 is rotated in the counterclockwise direction, and an unillustrated envelope, which is an image forming medium, is moved between the heating roll 111 and the belt 102 from below in the figure, and sandwiched between the heating roll 111 and the heating roll 111. The toner image transferred onto the envelope is fixed by being conveyed upward by the rotation of. At this time, the belt 102 rotates clockwise, and pressure from the pad member 123a is applied to the envelope (not shown) via the belt 102. In this way, the pressurization state shown in FIG. 7A is obtained, and a fixing process suitable for envelope printing is performed.

(Release mode)
As described above, the cam 108 is set to the “plain paper printing mode” by setting the cam 108 in the state of FIG. 1 and the “envelope printing mode” is set by setting the cam 108 to the state of FIG. Next, in a state where the image forming medium is sandwiched between the heating roll 111 and the belt 102 and the conveyance is poor (generally referred to as a jammed state or a paper jam state), the pressurizing device moves away from the heating roll 111. A mode (which will be referred to as a release mode) in which 123 is moved backward to facilitate removal of a jammed image forming medium will be described.

  In this case, the cam 108 is rotated 90 ° counterclockwise from the state of FIG. 1, or the cam 108 is rotated 180 ° from the state of FIG. 2 to obtain the state shown in FIG. In the state of FIG. 3, the positional relationship of the second support member 104 is the same as in the case of FIG. 2, but the fixed portion 110 of the coil spring 112 in the cam 108 is on the right side as compared with the case of FIG. 1 and FIG. Since it comes to (the side close to the first support member 103), the tensile force of the coil spring 112 is reduced. Further, since the coil spring 112 stands in the vertical direction of the drawing as compared with the case of FIGS. 1 and 2, the force pulling from the coil spring 112 to the first support member 103 in the negative direction of the X axis is shown in FIGS. It becomes smaller than the case of. For this reason, the pressure device 123 moves in the positive direction of the X axis, and a gap is formed between the pressure device 123 and the heating roll 111. Thus, the release mode is obtained. The retreat of the heating device 123 is limited by the stopper 116 provided on the second support member.

  In the release mode shown in FIG. 3, the state where pressure is applied to the heating roll 111 from the pressurizing device 123 is released, and a gap is formed between them (exactly, between the belt 102 and the heating roll 111). Therefore, a state in which the jammed image forming medium can be easily taken out is obtained.

  As described above, the link mechanism that couples the cam 108 and the first support member 103 with the coil spring 112 is employed, and the second support member 104 that rotatably supports the first support member with the cam 108. When the cam member is rotated, the first support member 103 coupled to the cam 108 rotates with respect to the second support member 104. At the same time, the second support member 104 is rotated with respect to the base member 106 by being pushed by the cam 108. By these two rotations, the direction of the pressure device 123 relative to the heating roll 111 changes. By selecting the orientation, (1) a plain paper printing mode in which the pad member 123a and the head member 123b pressurize the image forming medium, and (2) pressurization to the image forming medium by the pad member 123a is performed. Any one of the envelope printing modes in which no pressure is applied to the image forming medium by the head member 123b is selected. Further, the pressure applied to the pressurizing device 123 from the coil spring 114 via the second support member 104 is adjusted by the rotational position of the cam 108, and in the state of FIG. 1, the pressurized state of FIG. 7B is obtained. In the state of FIG. 2, the pressurized state of FIG. 7C is obtained.

(Image forming device)
Next, an example of an image forming apparatus provided with the fixing device shown in FIGS. FIG. 8 is a conceptual diagram illustrating an example of an image forming apparatus. FIG. 8 shows an image forming apparatus 800. The image forming apparatus 800 includes an image forming medium storage device 801. The image forming medium storage device 801 stores plain paper or an envelope as the image forming medium 802. A conveyance roller 803 is disposed on the downstream side of the image forming medium storage device 801 in the conveyance direction of the image forming medium.

  The image forming medium drawn out from the image forming medium storage device 801 by the conveying roller 803 is conveyed along the conveying path 804, electrostatically attracted to the conveying belt 805, and further conveyed upward. The mechanism of electrostatic adsorption is not shown in the figure. The conveyor belt 805 is tensioned between the driving roller 806 and the auxiliary roller 807, and rotates in the clockwise direction in the drawing by the driving force from the driving roller 806.

  Photosensitive drums 808a to 808d are sequentially arranged from the upstream side in the conveyance direction of the image forming medium adsorbed on the conveyance belt 805. Each photosensitive drum forms a toner image of each basic color of YMCK (Yellow, Magenta, Cyan, black). The photosensitive drum 808a is irradiated with scanning light for forming an electrostatic latent image from a raster optical scanner (ROS) 809a which is a writing exposure scanning device. Toner is supplied from the toner supply roll 810a to the portion where the latent image is formed, and a toner image corresponding to the latent image is formed on the photosensitive drum 808a. Since the photosensitive drum 808a is rotating, this toner image is transferred onto the image forming medium that is attracted to the transport belt 505 and transported.

  With a similar mechanism, the photosensitive drums 808b, ROS 809b and the toner supply roll 810b are arranged toward the downstream side, and further the photosensitive drums 808c, ROS 809c and the toner supply roll 810c are arranged, and further the photosensitive drums 808d, ROS 809d and A toner supply roll 810d is disposed.

  The image forming medium on which the toner image of the basic color selected from YMCK is transferred is output from the transport belt 805 to the transport path 811 and reaches the image fixing device 100. The image fixing apparatus 100 has the structure shown in FIGS. 1 to 3 and performs the operation described with reference to FIGS.

  If the image forming medium to be used is plain paper, the plain paper printing mode shown in FIG. 1 is selected in the image fixing apparatus 100. If the image forming medium to be used is an envelope, envelope printing shown in FIG. A mode is selected. When the image forming medium is jammed by the image fixing device 100, the release mode shown in FIG. 3 is selected. These modes are switched by rotating the cam 108 (see FIG. 1) manually, electrically, hydraulically, or the like.

  Note that the conveyance speed of the image forming medium is different between the plain paper printing mode and the envelope printing mode. These parameters are appropriately adjusted in conjunction with the rotation of the cam 103.

  Fixing of the toner image transferred onto the image forming medium is performed in the image fixing apparatus 100, whereby the image formation is completed. The image forming medium on which the image is formed is discharged to the discharge surface 814 through the conveyance roller 812 and the output roller 813. Thus, an image is formed on the image forming medium. The configuration of the image forming apparatus 800 can be used for a printing apparatus that performs printing based on image data sent from a terminal such as a personal computer, a FAX apparatus, a copying apparatus, or a composite apparatus having two or more of these functions. it can. Here, an example of an apparatus that forms a color image is shown, but an image forming apparatus that forms a monochrome image may be used. The image forming apparatus may be configured to primarily transfer a toner image from a photosensitive drum to an intermediate transfer member such as a transfer belt, and further transfer the toner image to an image forming medium.

(2) Second Embodiment The connection between the cam and the first support member can be performed not by a coil spring but by a link mechanism using a connecting rod. Hereinafter, this example will be described. FIG. 4 is a conceptual diagram showing an example of an image fixing apparatus using the invention. FIG. 4 shows an image fixing device 400. In the image fixing device 400, the cam 108 and the first support member 103 are coupled by a rod-shaped link member 401.

  One end of the link member 401 is fixed to a coupling point 402 that is distant from the center of rotation of the cam 108 in the longitudinal direction, and the other end is provided on the first support member 103 at a portion 404. The groove 403 is supported in a slidable and rotatable state. In other words, the other end of the link member 401 is constrained in a state where the reference numeral 404 serves as a fulcrum, and the fulcrum 404 is rotatable with respect to the first support member 103 and is slidable in the groove 403. . The other configuration is the same as that shown in FIG.

  Also in the image fixing device 400, any one of “plain paper printing mode”, “envelope printing mode”, and “release mode” is selected depending on the rotational position of the cam 108. The rotational position of the cam 108 corresponding to each mode is the same as in the case of the first embodiment. Hereinafter, an outline of a state in which each mode is selected will be described.

(Plain paper printing mode)
FIG. 4 shows a state when the plain paper printing mode is selected. In this case, the side on the short axis of the cam 108 faces the contact portion 113, and the coupling point 402 is positioned on the side close to the first support member 103 (the lower side in the figure). In this state, the pressure member 123 receives pressure from the coil spring 114 toward the heating roll 111 and applies pressure to the heating roll 111 side. Further, the above pressure is applied from both the pad member 123a and the head member 123b. For this reason, when an image forming medium (not shown) is sandwiched between the heating roll 111 and the belt 102 from below in the drawing, pressure is applied to the image forming medium from the pad member 123a and the head member 123b. Thus, the pressure distribution shown in FIG. 7B is obtained.

(Envelope printing mode)
When the cam 108 is rotated 90 ° in the clockwise direction from the state of FIG. 4, the envelope print mode is entered. FIG. 5 is a conceptual diagram showing an example of an image fixing device using the invention, and shows an example of an envelope printing mode state.

  In this state, the side on the long axis of the cam 108 contacts the contact portion 113 and pushes the second support member 104 away from the heating roll 111. On the other hand, since the coupling point 402 located on the long axis of the cam 108 moves in a direction away from the first support member 103, the fulcrum 404 moves in the groove 403 in the left direction and slightly in the upward direction. To do. For this reason, the pressurizing device 123 rotates in a direction in which the pressurizing surface is upward from the state shown in FIG. 4, the head member 123 b moves away from the heating roll 111, and only the pad member 123 a is in a state of applying pressure to the heating roll 111. In this way, a state where pressure to the image forming medium (not shown) is not applied from the head member 123b but is applied from the pad member 123a is obtained, and image fixing suitable for printing on the envelope is performed. At this time, by adjusting the dimension of the groove 403 and the length of the link member 401, the pressure applied by the heating device 123 in the direction of the heating roll 111 is smaller than that in the plain paper mode of FIG. In this way, the pressure distribution shown in FIG. 7A is obtained.

(Release mode)
When the cam 108 is rotated 180 ° from the state of FIG. 5, the mode shifts to the release mode. FIG. 6 is a conceptual diagram showing an example of an image fixing device using the invention, and shows an example of a state of a release mode.

  In this state, the coupling point 402 is closer to the first support member 103 than in the case of FIG. 3, so that the fulcrum 404 slides rightward in the groove 403, and is further The support member 103 is pushed in the right direction in the figure. Therefore, from the state of FIG. 5, the first support member 103 rotates counterclockwise about the rotation shaft 105, and the pressurizing device 123 moves in a direction away from the heating roll 111. Thereby, as shown in FIG. 6, a clearance gap arises between the pressurization apparatus 123 and the heating roll 111, and it will be in the state of cancellation | release mode.

(3) Other Embodiments Three or more types of pressure members may be included in the pressure device 123. Further, the position of the rotation center of the cam 108 may be shifted from the center of the ellipse, and the contact state of the pressure device in each mode may be adjusted. Further, the elliptic shape of the cam 108 may not be an accurate ellipse. The cam may have a polygonal shape in which a plurality of distances from the rotation center to the side are set. As the printing mode, a pressurization state suitable for thick paper or resin-made printing paper may be selected. Further, the number of modes selected by the cam may be increased, and three or more print modes may be used.

  Further, depending on the material and thickness of the image forming medium, it may be preferable to apply pressure to the image forming medium only from the hard head member 123b. In order to cope with such a case, a mode in which the pad member 123a is retracted and the pressure from the head member 123b is applied to the printing paper may be set. A cylinder using hydraulic pressure or air pressure may be used instead of the coil spring. Further, in order to set the plain paper printing mode shown in FIG. 1, the cam 108 may be rotated so that the coil spring fixing portion 110 is positioned at a rotational position (that is, the upper side) different from that of FIG. In this case, the spring constant and tension of the coil spring 112 and other member positions and dimensions may be finely adjusted so as to realize a pressurized state suitable for printing on plain paper.

  The present invention can be used for an image fixing apparatus and an image forming apparatus using the same.

1 is a conceptual diagram illustrating an example of an image fixing device using the invention. 1 is a conceptual diagram illustrating an example of an image fixing device using the invention. 1 is a conceptual diagram illustrating an example of an image fixing device using the invention. 1 is a conceptual diagram illustrating an example of an image fixing device using the invention. 1 is a conceptual diagram illustrating an example of an image fixing device using the invention. 1 is a conceptual diagram illustrating an example of an image fixing device using the invention. FIG. 4 is a conceptual diagram illustrating a state of pressure applied to an image forming medium in an image fixing device. 1 is a conceptual diagram illustrating an example of an image forming apparatus.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100 ... Image fixing apparatus, 101 ... Cylindrical member, 102 ... Belt, 103 ... 1st support member, 104 ... 2nd support member, 105 ... Rotating shaft, 106 ... Base member, 107 ... Rotating shaft, 108 ... Cam, DESCRIPTION OF SYMBOLS 109 ... Rotating shaft, 110 ... Coil spring fixed part, 111 ... Heating roll, 112 ... Coil spring, 113 ... Contact part, 114 ... Coil spring, 115 ... Coil spring support member, 123 ... Pressurizing device, 123a ... Pad member, 123b ... Head member , 401 ... Link member, 402 ... Connection point, 493 ... Groove, 404 ... Support point.

Claims (9)

A pressurizing means having a plurality of pressurizing parts having different hardnesses;
A first support member for supporting the pressurizing means;
A second support member for supporting the first support member in a rotatable state;
A base member for supporting the second support member in a rotatable state;
Opposing means arranged opposite to the pressurizing means and disposed on the foundation member;
A cam member which is arranged in a rotatable state, is coupled to the first support member, and pushes the second support member in a direction in which the pressurizing means separates from the opposing means. Fixing device. The cam member has a first side, and a second side and a third side that are farther from the rotation center of the cam member than the first side,
The first support member is coupled to the third side of the rotation center.
In a state where the first side faces the second support member, a fixing process of a toner image on the first image forming medium is performed,
2. The image fixing device according to claim 1, wherein the toner image is fixed to the second image forming medium in a state where the second side is in contact with the second support member. The pressurizing unit has a first member and a second member that is softer than the first member,
In a state where the first side faces the second support member, the first member and the second member exert pressure on the first image forming medium between the opposing means. In addition,
In a state where the second side is in contact with the second support member, the first member does not apply pressure to the second image forming medium, and the second member is the counter means. The image fixing apparatus according to claim 2 , wherein a pressure is applied to the second image forming medium in between.
  When the third side comes into contact with the second supporting member, the toner image fixing process on the first image forming medium and the toner image fixing process on the second image forming medium are performed. The image fixing apparatus according to claim 2, wherein a distance between the facing unit and the pressing unit is larger than a state in which it is performed. The cam member has an elliptical shape,
The first side is located on the minor axis;
The second side and the third side are located on the major axis,
5. The image fixing device according to claim 2, wherein the second side and the third side are located at a position sandwiching a rotation center of the cam member.   The image fixing apparatus according to claim 1, further comprising a pressure generating unit that applies pressure to press the second support member in the direction of the cam member.   The image fixing apparatus according to claim 1, wherein the first support member and the cam member are coupled by a coil spring.   The coupling between the first support member and the cam member is a coupling that is movable and supported by the first support member in a rotatable state, and supported by the cam member in a rotatable state. The image fixing device according to claim 1, wherein the image fixing device is a member. Toner image forming means for forming a toner image;
An image forming apparatus comprising: the image fixing device according to claim 1.

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