JP6056568B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device used in an image forming apparatus such as a copying machine, a printer, and a facsimile, and an image forming apparatus including the same.

  In recent years, market demands for energy saving and speeding up of image forming apparatuses such as copying machines, printers, and facsimiles have increased. In an image forming apparatus, an image is formed by an image forming process such as electrophotographic recording, electrostatic recording, or magnetic recording, and an unfixed toner image is recorded on a recording material sheet, printing paper, photosensitive paper, electrostatic It is formed on a recording material such as recording paper. As a fixing device for fixing an unfixed toner image, a contact heating method fixing device such as a heat roller method, a film heating method, or an electromagnetic induction heating method is widely used.

  As an example of such a fixing device, a belt-type fixing device is known (see, for example, Patent Document 1).

  However, in such a belt-type fixing device, it is desired to further shorten the time required for warm-up and first printing. The warm-up time refers to the time required from a normal temperature state to a predetermined printable temperature (reload temperature) such as when the power is turned on. The first print time is a time period from when a print request is received to when a print operation is performed through print preparation and paper discharge is completed.

  In order to shorten the warm-up time and the first print time, a surf fixing type (film fixing type) fixing device using a ceramic heater has been proposed (see, for example, Patent Document 2). This surf-fixing type fixing device can be reduced in heat capacity and size as compared with a belt-fixing type fixing device.

  However, this fixing device locally heats only the fixing nip portion. For this reason, the other portions are not heated, and there is a problem that the belt is in the coldest state in the vicinity of the carry-in entrance of the sheet or the like in the fixing nip portion, so that fixing failure is likely to occur. In particular, in a high-speed machine, there is a problem that fixing failure is more likely to occur because the belt rotates fast and the heat radiation of the belt outside the fixing nip increases.

  Further, as the speed of the image forming apparatus increases, the number of sheets to be passed per unit time increases and the required heat amount increases. For this reason, so-called temperature drop in which the amount of heat is insufficient at the beginning of continuous printing is also a problem.

  In order to solve the above-described problems, there has been proposed a fixing device that can heat the entire belt in a configuration using an endless belt (see, for example, Patent Document 3).

  As shown in FIG. 9, the fixing device described in Patent Document 3 is provided with an endless belt 100, a pipe-shaped metal heat conductor 200 disposed inside the endless belt 100, and a metal heat conductor. The heat source 300 and the pressure roller 400 that forms the nip portion N in contact with the metal heat conductor 200 via the endless belt 100 are provided. The endless belt 100 is driven and rotated by the rotation of the pressure roller 400. At this time, the metal thermal conductor 200 guides the movement of the endless belt 100. Further, the endless belt 100 is heated through the metal heat conductor 200 by the heat source 300 in the metal heat conductor. With such a configuration, the entire endless belt constituting the fixing device can be warmed. For this reason, the first print time from the heating standby time can be shortened, and the shortage of heat at the time of high-speed rotation can be solved.

  However, such a fixing device is required to further save energy and improve the first print time.

  In order to further save energy and improve the first print time, a configuration in which an endless belt is directly heated without using a metal heat conductor has been proposed (for example, see Patent Document 4).

  In the fixing device described in Patent Document 4, the pipe-shaped metal heat conductor is removed from the inside of the endless belt, and a plate-shaped nip forming member is provided instead. A pressure roller that forms a nip portion by contacting the nip forming member via an endless belt is provided. In the case of this configuration, the endless belt can be directly heated by the heat source other than the portion where the nip forming member is disposed. Therefore, heat transfer efficiency is greatly improved and power consumption is reduced. Thereby, the first print time from the heating standby time can be further shortened. In addition, the cost can be reduced without using a metal heat conductor.

  However, in this type of fixing device that directly heats the endless belt, the heat of the endless belt cannot escape to the metal conductor or the like. Therefore, under certain conditions, the temperature of a part of the endless belt rises extremely. For example, various sizes of paper are used in the image forming apparatus. When the heating source is longer than the paper width, the endless belt outside the paper width is not absorbed by the paper when the paper is passed. In particular, when small-size paper is continuously passed, the endless belt outside the paper width is heated for a certain period of time as shown in FIG. And an endless belt will become high temperature by being heated excessively, and causes the possibility of receiving damage or breaking.

  In order to solve such a problem, a fixing device that includes a thermostat and adjusts heating when an endless belt is excessively heated has been proposed (for example, Patent Document 5).

  According to the fixing device described in Patent Document 5, when the endless belt is heated and the endless belt rises above a predetermined temperature, the thermostat detects this and stops the operation of the heat source. Therefore, an excessive temperature rise of the endless belt can be prevented.

However, the fixing device described in Patent Document 5 decreases in productivity as the heat source stops operating.

  It is also conceivable to equip a plurality of heaters according to each paper width. However, it is not preferable to provide a large number of heaters in terms of apparatus size and cost.

  On the other hand, a fixing device that prevents the end temperature of the endless belt from rising by providing a shielding plate is not yet known at the time of the present application, but is proposed in, for example, Patent Application 2012-202616 or Patent Application 2012-202302.

  According to the fixing device described above, the end plate temperature rise of the endless belt can be prevented by arranging the shielding plate for shielding the heat from the heater between the heater and the endless belt. Specifically, an area unnecessary for heating can be shielded by providing a shielding plate having a notch adapted to each paper width. Therefore, it is possible to prevent an excessive increase in the end temperature of the endless belt in response to various sizes of paper without reducing productivity.

  However, the shielding plate provided in the fixing device is always heated from the heater except when the paper having the maximum paper passing width is passed. Therefore, the temperature of the shielding plate is likely to be higher than that of other members. Specifically, when the heater does not always light so that several sheets are printed, the temperature of the shielding plate does not become extremely high. On the other hand, when the heater is always turned on as in continuous paper passing, the temperature of the shielding plate continues to rise and becomes very high. Therefore, the temperature of the shielding plate tends to be high.

  In particular, when the shielding plate is held only by the rotating member that is a heat insulating member, the temperature of the shielding plate continues to rise. And it is possible that a shielding board expand | swells and deform | transforms and contacts an endless belt or a stay member. Further, when the rotating member is formed of resin or the like, when the shielding plate becomes high temperature, there is a possibility that thermal deformation may occur exceeding the heat resistance temperature of the rotating member.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device having a simple configuration that can save energy and improve a first print time, and can suppress an increase in end temperature without reducing productivity.

In order to solve the above-described problem, a fixing device according to a first aspect of the present invention includes:
A fixing rotator,
A heat source for heating the fixing rotator;
A non-rotating nip forming member that contacts the fixing rotator inside the fixing rotator;
A pressure member that forms a nip with the nip forming member via the fixing rotator, and
A fixing device including a support member that receives pressure applied to the nip forming member,
A shielding member movable between the inner surface of the fixing rotator and the heat source;
The shielding member is always in contact with the support member.

  According to the present invention, it is possible to provide a fixing device having a simple configuration capable of saving energy and improving the first print time and suppressing an increase in end temperature without reducing productivity.

1 is a configuration diagram schematically illustrating an image forming apparatus according to a first embodiment of the present invention. FIG. 2 is a cross-sectional view schematically showing a fixing device of the image forming apparatus shown in FIG. 1. It is explanatory drawing explaining the halogen heater used for the image forming apparatus shown in FIG. FIG. 2 is an explanatory diagram illustrating heating of a fixing belt provided in the image forming apparatus illustrated in FIG. 1. FIG. 3 is an explanatory diagram illustrating a shielding member provided in the image forming apparatus illustrated in FIG. 1. FIG. 5 is a cross-sectional view schematically illustrating a fixing device of an image forming apparatus according to a second embodiment of the present invention. FIG. 5 is a cross-sectional view schematically illustrating a fixing device of an image forming apparatus according to a third embodiment of the present invention. FIG. 6 is a cross-sectional view schematically illustrating a fixing device of an image forming apparatus according to a fourth embodiment of the present invention. FIG. 10 is a cross-sectional view schematically showing a conventional fixing device. It is explanatory drawing explaining the edge part temperature rise of a fixing rotary body.

  Next, a first embodiment according to the present invention will be described below with reference to the drawings. In each drawing for explaining the present embodiment, constituent elements such as members or components having the same function or shape are given the same reference numerals as much as possible, and once explained, the explanation will be given. Is omitted.

  FIG. 1 is a schematic sectional view showing an example of a color printer as an image forming apparatus 10 provided with a fixing device of the present invention. The image forming apparatus 10 shown here includes a fixing device 50 to be described later and an electrophotographic image forming unit, and the image forming unit includes a plurality of (four in the illustrated example) image forming means 1a, 1b, 1c and 1d are provided. Although the first to fourth image forming units 1a, 1b, 1c and 1d have the same configuration, only the corresponding toner colors are different. Therefore, for example, a black toner image, a magenta toner image, a cyan toner image, and a yellow toner image are formed in these image forming units. Since these image forming units have the same configuration except for the difference in developer (toner) color, in the following description, the subscripts a, b, c, and d in the reference numerals are omitted as appropriate. To do.

  The image forming unit 1 is provided with a drum-shaped photoconductor 2 that is an electrostatic latent image carrier. A charging member 3, a developing device 4, and a cleaning unit 5 are provided around the photoconductor 2. Yes. The photoreceptor 2 can be driven to rotate clockwise, and a charging member 3 is pressed against the surface of the photoreceptor 2. The charging member 3 is driven to rotate as the photosensitive member 2 rotates. In addition, a predetermined bias voltage is applied to the charging member 3 from a high voltage power source (not shown) so that the surface of the photoconductor 2 to be rotationally driven can be uniformly charged. The charging member 3 shown here employs a roller-shaped member that contacts the photosensitive member 2, but a non-contact type utilizing corona discharge or the like can also be employed.

  Further, in the image forming apparatus 10 shown in FIG. 1, an exposure device 6 is provided obliquely downward in parallel with the four image forming means. The exposure apparatus 6 has appropriate components such as a light source, a polygon mirror, an f-θ lens, and a reflection mirror. Then, each photoreceptor 2 charged by the charging member 3 is exposed based on image information formed according to the image data of each color toner. And it is provided in order to create an electrostatic latent image on each photoconductor 2. The electrostatic latent image formed on the photosensitive member 2 using the exposure device 6 is developed and visualized by applying toner of each color when passing through the developing device 4 by the rotation of the photosensitive member 2. The In addition, toner bottles 20a, 20b, 20c, and 20d filled with black, magenta, cyan, and yellow toners are disposed above the image forming apparatus 10. A predetermined replenishment amount of toner is replenished from the toner bottles 20a, 20b, 20c and 20d to the color developing devices 4a, 4b, 4c and 4d via a conveyance path (not shown).

  Further, an endless belt-shaped intermediate transfer belt 7 configured as an intermediate transfer member is disposed opposite to the photoreceptor 2 of each image forming unit, and each photoreceptor 2 is applied to the surface of the intermediate transfer belt 7. It touches. The intermediate transfer belt 7 shown in FIG. 1 is configured by being wound around a plurality of support rollers (for example, support rollers 15a and 15b). In the illustrated example, the support roller 15a is coupled to a drive motor as a drive source (not illustrated). By driving this drive motor, the intermediate transfer belt 7 is rotated counterclockwise in the drawing, and the support roller 15b that can be driven and rotated is rotated. Further, on the back surface of the intermediate transfer belt 7, a primary transfer roller 8 is disposed so as to face the photoconductor 2 with the belt interposed therebetween. A primary transfer bias is applied to the primary transfer roller 8 from a high voltage power source (not shown), and the toner image visualized by the developing device 4 is primarily transferred to the intermediate transfer belt 7. The primary transfer residual toner that is left on the photosensitive member 2 without being primarily transferred is removed by the cleaning unit 5 in preparation for the next image forming operation by the photosensitive member 2, and the toner on the photosensitive member 2 is completely removed. Removed.

  Further, in the illustrated image forming apparatus 10, a secondary transfer roller 18 as a secondary transfer device is provided downstream of the primary transfer roller 8 in the driving direction of the intermediate transfer belt 7. The secondary transfer roller 18 faces the support roller 15b with the intermediate transfer belt 7 interposed therebetween. The secondary transfer roller 18 and the support roller 15b form a secondary transfer nip portion via the intermediate transfer belt 7. Further, the image forming apparatus 10 includes a registration roller pair (positioning roller pair) 35 and the like in addition to a paper feeding cassette 30 and a feeding roller 31 as a recording medium stacking unit. A fixing device 50 and a paper discharge roller pair 36 are provided on the downstream side in the conveyance direction of the recording medium when viewed from the secondary transfer roller 18.

  Next, an image forming operation will be described. Also in this image forming operation, the configuration in which a toner image is formed on each photoconductor 2 and the toner image is transferred to the intermediate transfer belt 7 is substantially the same except that the color of the toner image is different. , A, b, c, and d are omitted as necessary.

  First, the above-described photoconductor 2 is rotated in a clockwise direction by a drive source (not shown), and at this time, light from a static eliminator (not shown) is irradiated on the surface of the photoconductor to initialize the surface potential. The surface of the photoreceptor 2 having the surface potential initialized is uniformly charged to a predetermined polarity by the charging member 3 this time. The charged photoconductor surface is irradiated with laser light from the exposure device 6, whereby an electrostatic latent image is formed on the photoconductor surface. At this time, the image information exposed on each photoreceptor 2 is single-color image information obtained by separating a desired full-color image into yellow, cyan, magenta, and black toner color information. The electrostatic latent image formed on the photosensitive member in this way is visualized as a visualized toner image by being supplied with each color toner (developer) from the developing device 4 when passing through the developing device 4. .

  The intermediate transfer belt 7 is driven to run counterclockwise in the drawing. The primary transfer roller 8 is applied with a primary transfer voltage having a polarity opposite to the toner charging polarity of the toner image formed on the photoreceptor. As a result, a transfer electric field is formed between the photosensitive member 2 and the intermediate transfer belt 7. Then, the toner image on the photoreceptor 2 is electrostatically primary-transferred onto the intermediate transfer belt 7 that is rotationally driven in synchronization with the photoreceptor 2. In this manner, the color toner images that are primarily transferred are superimposed on the intermediate transfer belt 7 sequentially at the same timing from the upstream side in the transport direction of the intermediate transfer belt 7 to form a desired full-color image.

  On the other hand, the recording medium on which an image is to be formed is separated one by one from the recording medium bundle loaded in the paper feeding cassette 30 to the registration roller pair 35 by the action of an appropriate conveying member such as the feeding roller 31. To be fed. At that time, the leading edge of the conveyed recording medium comes into contact with the nip portion of the registration roller pair 35 that has not yet started to rotate and forms a so-called loop, thereby registering the recording medium. . Thereafter, rotation of the registration roller pair 35 is started at the timing of the full-color toner image carried on the intermediate transfer belt 7. Then, the recording medium is sent out toward the secondary transfer nip portion constituted by the support roller 15b and the secondary transfer roller 18 facing the support roller 15b via the intermediate transfer belt 7. In this embodiment, a transfer voltage having a polarity opposite to the toner charging polarity of the toner image on the surface of the intermediate transfer belt is applied to the secondary transfer roller 18. As a result, the full color toner image formed on the surface of the intermediate transfer belt 7 is collectively transferred onto the recording medium. The recording medium to which the toner image is transferred is further conveyed to the fixing device 50. Then, when passing through the fixing device 50, heat and pressure are applied, and the toner image is fixed on the recording medium as a permanent image. The recording medium after image formation with the image fixed is discharged to a recording medium discharge section such as a discharge tray via a pair of discharge rollers 36, thereby completing the image forming operation. The residual toner remaining on the intermediate transfer belt 7 without being transferred at the secondary transfer nip portion where the secondary transfer roller 18 is disposed is removed and collected by the intermediate transfer belt cleaning means 19.

  Next, the configuration and operation of the fixing device 50 will be described below with reference to FIG. For convenience of explanation, for example, the following four types of paper used in the image forming apparatus of the present embodiment will be described.

  The paper size A is the maximum size (A3 Nobi or the like) used in the image forming apparatus of the present embodiment. The paper size B is a size 1 (A3 vertical, A4 horizontal, etc.) that is often used in the market. The paper size C is size 2 (A4 portrait, etc.) that is often used in the market. The paper size D is a small size paper (such as a postcard). The paper size is an example and is not limited to the description.

  The fixing device includes a pressure roller as the pressure rotator 70 and a fixing belt as the fixing rotator 60. The fixing belt 60 is directly heated from the inner peripheral side by radiant heat from a halogen heater as the heating source 61. Is done. Further, a nip forming member 65 that forms a nip portion N with a pressure roller 70 opposed via the fixing belt 60 is provided. The nip forming member 65 slides directly with the inner peripheral surface of the fixing belt.

  The nip forming member 65 is non-rotating and is disposed in the fixing belt. The nip forming member 65 slides directly with the inner peripheral surface of the fixing belt. In addition, you may slide indirectly with the inner surface of a fixing belt via a sliding sheet (not shown). In the present embodiment, the nip portion N has a flat shape, but may have a concave shape or other shapes. When the shape of the nip forming member is a concave shape, the discharge direction from the nip portion N at the leading end of the recording paper is closer to the pressure roller. Therefore, the separation property of the recording paper P from the fixing belt 60 is improved, and the occurrence of jam can be suppressed.

  The fixing belt 60 is an endless belt using a metal belt such as nickel or SUS or a resin material such as polyimide. The surface layer of the fixing belt 60 has a release layer (not shown) such as a PFA or PTFE layer, and has a release property so that toner does not adhere. Further, an elastic layer (not shown) formed of a silicone rubber layer or the like is provided between the base material (not shown) of the fixing belt 60 and the release layer.

  Here, when the fixing belt does not have a silicone rubber layer, the heat capacity is reduced and the fixing property is improved. However, when the unfixed image is crushed and fixed, a minute unevenness on the surface of the fixing belt is transferred to the image, and there is a problem that a crusty glossy unevenness (skin skin image) remains on the solid portion of the image. . In order to prevent such a problem, a silicone rubber layer is provided with a thickness of 100 μm or more. As a result, the silicone rubber layer is deformed, minute irregularities are absorbed, and a skin image can be prevented.

  Inside the fixing belt 60, a stay is provided as a support member 66 for supporting the nip forming member 65. The support member 66 is made of a metal such as stainless steel, iron, or aluminum, and prevents the nip forming member 65 from bending due to the pressing force of the pressure roller 70. A uniform nip width can be obtained over the longitudinal direction of the fixing belt 60. The support member 66 is fixed and held on a holding member (not shown) at both ends in the longitudinal direction and positioned.

  As shown in FIG. 3, two halogen heaters 61 are used. The two halogen heaters 61 have different heat generation ranges. Then, the fixing belt 60 can be heated according to the size of the paper that is passed through the fixing device 50. Specifically, the fixing device 50 according to the present embodiment heats a position corresponding to the longitudinal end region of the fixing belt 60 and a central heater 61 a that heats the position corresponding to the longitudinal central region of the fixing belt 60. Two end heaters 61b are provided. As shown in FIG. 3A, when passing a wide sheet B such as A3 length, both the central heater 61a and the end heater 61b are turned on. On the other hand, as shown in FIG. 3B, when passing a narrow sheet C such as A4 portrait, only the central heater 61a is turned on. Therefore, the power consumption used for heating the fixing belt 60 can be suppressed. In addition, although the two halogen heaters 61 are used in this embodiment, it cannot be overemphasized that it is not limited to this aspect.

  A reflective member 67 is provided between the halogen heater 61 and the support member 66. And the thing which vapor-deposited silver on the surface of an aluminum base material is used for the reflection member 67. FIG. Therefore, the surface of the reflection member 67 has a low emissivity, and radiant heat from the halogen heater 61 toward the support member is reflected to the fixing belt 60. Therefore, the heating efficiency of the fixing belt 60 can be improved.

  Specifically, as shown in FIG. 4, the radiant heat from the halogen heater 61 is directly heated toward the fixing belt 60 (solid arrow in FIG. 4) and reflected by the reflecting member 67 to be reflected on the fixing belt 60. And indirect heating (broken arrows in FIG. 4). The fixing belt 60 can be efficiently heated by using both the direct heating and the indirect heating. Further, useless energy consumption that occurs when the support member 66 is heated from the halogen heater 61 can be suppressed. Needless to say, the material of the reflecting member is not limited to this mode. Further, instead of providing the reflecting member 67, the support member surface may be heat-insulated or mirror-finished.

  Needless to say, the heat source is not limited to two heaters as in the present embodiment, and may be one or other modes. Further, the heat source 61 is not limited to the halogen heater, but may be IH, a resistance heating element, a carbon heater, or the like.

  As shown in FIG. 2, the pressure roller 70 has a solid core metal 72 covered with an elastic rubber layer 71, and a release layer (not shown) made of a PFA or PTFE layer on the surface in order to obtain release properties. ) Is provided. The pressure roller 70 is rotated by a driving force transmitted from a driving source (not shown) such as a motor provided in the image forming apparatus via a gear (not shown). The pressure roller 70 is pressed against the fixing belt 60 by a spring (not shown) or the like. The elastic rubber layer 71 is crushed and deformed to have a predetermined nip width.

  The pressure roller 70 may be a hollow roller, and the pressure roller 70 may have a heat source such as a halogen heater. The elastic rubber layer 71 may be solid rubber. When there is no heater inside the pressure roller, the elastic rubber layer may use sponge rubber. By using sponge rubber for the elastic rubber layer, the heat insulating property is enhanced and the heat of the fixing belt is hardly taken away.

  The fixing belt 60 is rotated by the pressure roller 70. Specifically, when the pressure roller 70 is rotated by a driving source (not shown), the driving force is transmitted to the fixing belt 60 through the nip portion N. The fixing belt 60 travels while being guided by holding members (not shown) at both ends thereof.

  The shielding member 62 is disposed inside the fixing belt 60 as shown in FIG. Further, as shown in FIG. 5, the shielding member 62 has a notch having a stepped shape so as to shield the radiant heat from the heat source 61 corresponding to each paper width of the papers A to D. Then, the shielding member 62 moves in a non-contact manner along the inner peripheral surface of the fixing belt 60 to a position where the radiant heat from the heat source 61 can be shielded corresponding to each sheet width. Then, the fixing belt 60 is heated corresponding to each paper width through which the paper is passed.

  Specifically, for example, when the sheet A is passed, the shielding member 62 shields radiant heat that heats an unnecessary area out of radiant heat to the fixing belt 60 by a known driving unit (not shown). To the position (the shielding position corresponding to the paper A). Further, when the paper B is passed, the shielding member 62 is a position (shielding corresponding to the paper B) that shields radiant heat that heats an unnecessary area among radiant heat to the fixing belt 60 by a known driving unit. Position). Further, when the paper C is passed, the shielding member 62 is a position (shielding corresponding to the paper C) that shields radiant heat that heats an unnecessary area among radiant heat to the fixing belt 60 by a known driving unit. Position). Further, when the paper D is passed, the shielding member 62 is shielded by a known driving unit to shield the radiant heat that heats unnecessary areas of the radiant heat to the fixing belt 60 (the shield corresponding to the paper D). Position).

  Therefore, an area unnecessary for heating the fixing belt 60 can be shielded according to the paper size. As a result, even when transfer paper having a narrow paper width is continuously passed, the fixing belt 60 in the non-sheet passing area does not go into an excessively high temperature state, and the productivity is lowered to eliminate the excessively high temperature state. There is no need for control.

  Then, the paper P on which the toner image T is transferred is passed through the fixing nip N, and the toner image T is pressed and heated to be fixed on the paper P.

  Next, the shielding plate and the support member, which are characteristic configurations of the present invention, will be described. FIG. 2 is a cross-sectional view showing a cross section of the fixing device 50 in S1-S1 of FIG. The shielding member 62 is always in contact with the support member 66 at both ends thereof. Specifically, the shielding member 62 is connected to the support member 66 at all positions of the shielding position corresponding to the paper A, the shielding position corresponding to the paper B, the shielding position corresponding to the paper C, and the shielding position corresponding to the paper D. Contact. Then, the heat of the heated shielding member 62 is transmitted from the shielding member 62 to the support member 66. In addition, the site | part which the shielding member 62 contacts the support member 66 is not limited to this aspect, You may contact in one edge part, or you may contact in parts other than an edge part. Moreover, the structure of providing a convex shape in an inner peripheral direction in a shielding member, and contacting a support member may be sufficient.

  Next, the operation of the image forming apparatus according to this embodiment will be described.

  Since the shielding member 62 is always in contact with the support member 66, the heat of the shielding member 62 is released to the support member 66 and the heat is not accumulated in the shielding member 62. Therefore, the shielding member 62 becomes extremely hot, and the occurrence of thermal deformation of the shielding member itself and peripheral members can be prevented.

  Further, since the shielding member 62 is in direct contact with the support member 66, the heat of the shielding member 62 can be directly released to the support member 66. Therefore, a simple configuration can be achieved and cost reduction can be achieved.

  In addition, since the image forming apparatus includes the fixing device 50 described above, it is possible to provide an image forming apparatus having a simple configuration capable of saving energy and improving the first print time and suppressing an increase in the end temperature without reducing productivity. .

  Next, a second embodiment according to the present invention will be described below with reference to the drawings. In addition, about the structure equivalent to 1st Embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. 6 is a cross-sectional view showing a cross section of the fixing device 51 in S1-S1 of FIG.

  According to the present embodiment, the shielding member 62 is always in contact with the support member 166 via the heat transfer member 80. Specifically, the shielding member 62 includes the heat transfer member 80 at all positions of the shielding position corresponding to the paper A, the shielding position corresponding to the paper B, the shielding position corresponding to the paper C, and the shielding position corresponding to the paper D. It contacts with the support member 166 via. The heat transfer member 80 is preferably made of a material having high heat transfer properties such as copper or graphite sheet. The heat transfer member 80 has a sheet shape so as not to apply a load to the operation of the shielding member 62. The heat transfer member 80 is connected to the upstream end of the shielding member 62 in the rotation direction of the fixing belt 60 so that the heat transfer member itself is not heated. Further, the heat transfer member 80 is installed at a position of the support member 166 away from the heater 61 so that the heat transfer member itself is not heated. Then, the heat of the heated shielding member 62 is transmitted from the shielding member 62 to the support member 166 through the heat transfer member 80. Needless to say, the position at which the heat transfer member 80 is connected to the shielding member 62 and the support member 166 is not limited to this mode. Further, the heat transfer member is not limited to this aspect, and may be a metal member having a good thermal conductivity in the shape of an elastic leaf spring or the like.

  Since the shielding member 62 contacts the support member 166 via the heat transfer member 80, in addition to the operation of the first embodiment, it is possible to cope with a flexible design without worrying about the layout of the shielding member 62 and the support member 166. . Further, since the heat transfer member 80 has a sheet shape, the fixing device 51 can be reduced in weight.

  Next, a third embodiment according to the present invention will be described below with reference to the drawings. In addition, about the structure equivalent to 1st Embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 7 is a cross-sectional view showing a cross section of the fixing device 52 in S2-S2 of FIG.

  According to this embodiment, the shielding member 62 and the support member 266 are both in a contact state and a non-contact state. Specifically, the shielding member 62 comes into contact with the support member 266 at the central portion in the longitudinal direction of the shielding member 62 at the shielding position corresponding to the paper D. On the other hand, when the shielding member 62 is in the shielding position corresponding to the paper A, the shielding position corresponding to the paper B, or the shielding position corresponding to the paper C, the shielding member 62 does not contact the support member 266. Therefore, the heat stored in the shielding member 62 is transmitted to the support member 266 at a position where the shielding member 62 hides the heater 61 most, that is, a position where the shielding member 62 is most heated.

  By making the shielding member 62 contactable and separable from the support member 266, the shielding member 62 can be brought into contact with the support member 266 when the shielding member 62 reaches a high temperature. Therefore, energy can be saved as compared with a fixing device in which the shielding member is always in contact with the support member.

  The position where the shielding member 62 and the support member 266 are in contact may be other than the central portion of the shielding member 62. Further, the support member may be contacted at a position other than the shielding position corresponding to the paper D. And the detection means (not shown) which detects the temperature of the shielding member 62, and the well-known control means (not shown) which act | operates so that the shielding member 62 may be made to contact a support member with the detection information from a detection means are provided. Also good.

  With such a configuration, it is possible to optimize the timing for transmitting the heat of the shielding member 62 to the support member 266. Therefore, the temperature in the fixing member can be stabilized and energy saving can be achieved. Note that the detection unit may detect the temperature of the fixing rotator 60 instead of detecting the temperature of the shielding member 62. Further, the detecting means may detect the temperature of the shielding member 62 and the fixing rotating body 60. By detecting the temperature of the shielding member 62 and the fixing rotator 60, the detection accuracy can be improved.

  Next, 4th Embodiment which concerns on this invention is described below according to drawing. In addition, about the structure equivalent to 1st Embodiment mentioned above, a corresponding code | symbol is attached | subjected and detailed description is abbreviate | omitted. FIG. 8 is a cross-sectional view showing a cross section of the fixing device 53 in S2-S2 of FIG.

  According to the present embodiment, the shielding member 62 and the support member 366 are in both a contact state and a non-contact state via the heat transfer member 180. Specifically, the shielding member 62 comes into contact with the support member 366 via the heat transfer member 180 at the central portion in the longitudinal direction of the shielding member 62 at the shielding position corresponding to the paper D. On the other hand, when the shielding member 62 is at the shielding position corresponding to the paper A, the shielding position corresponding to the paper B, or the shielding position corresponding to the paper C, the shielding member 62 does not contact the support member 366 via the heat transfer member 180. Therefore, the heat stored in the shielding member 62 is transmitted to the support member 366 via the heat transfer member 180 at a position where the shielding member 62 hides the heater 61 most, that is, a position where the shielding member 62 is most heated.

  Since the shielding member 62 can be brought into and out of contact with the support member 366 via the heat transfer member 180, the shielding member 62 can be brought into contact with the support member 366 when the shielding member 62 reaches a high temperature. Therefore, energy can be saved as compared with a fixing device in which the shielding member is always in contact with the support member.

  The position where the shielding member 62 and the support member 366 are in contact with each other via the heat transfer member 180 may be other than the central portion of the shielding member 62. Further, the support member 366 may be in contact with the heat transfer member 180 at a position other than the shielding position corresponding to the paper D. Then, a known control unit (not shown) that detects the temperature of the shielding member 62 and a known control unit that operates the contact member 62 to contact the support member via the heat transfer member 180 based on detection information from the detection unit. (Not shown) may be provided.

  With such a configuration, it is possible to optimize the timing at which the heat of the shielding member 62 is transmitted to the support member 366 via the heat transfer member 180. Therefore, the temperature in the fixing member can be stabilized and energy saving can be achieved. Note that the detection unit may detect the temperature of the fixing rotator 60 instead of detecting the temperature of the shielding member 62. Further, the detecting means may detect the temperature of the shielding member 62 and the fixing rotating body 60. By detecting the temperature of the shielding member 62 and the fixing rotator 60, the detection accuracy can be improved.

  As mentioned above, although embodiment of this invention was described, this invention is not limited to this. Needless to say, the shield member and the support member can always be in contact with each other and can be in either contact or non-contact state depending on how the unit is used.

  It should be noted that the materials and dimensions of each component introduced in the above-described embodiment are merely examples, and it is needless to say that various materials and dimensions can be selected within a range where the effects of the present invention can be exhibited.

10 Color printer (an example of an image forming apparatus)
50, 51, 52, 53 Fixing device 60 Endless belt (an example of a fixing rotator)
70 Pressure roller (an example of a pressure rotator)
61 Halogen heater (example of heat source)
65 Nip forming member 62 Shield member 66,166,266,366 Stay (an example of a support member)
80,180 Heat transfer member N Fixing nip

JP 2004-286922 A Japanese Patent No. 2861280 JP 2007-334205 A JP 2011-186275 A Japanese Patent No. 2012-85742

Claims (8)

A fixing rotator,
A heat source for heating the fixing rotator;
A non-rotating nip forming member that contacts the fixing rotator inside the fixing rotator;
A pressure rotator that forms a nip with the nip forming member via the fixing rotator; and
A fixing device including a support member that receives pressure applied to the nip forming member,
A shielding member movable between the inner surface of the fixing rotator and the heat source;
The fixing device, wherein the shielding member is always in contact with the support member. A fixing rotator,
A heat source for heating the fixing rotator;
A non-rotating nip forming member that contacts the fixing rotator inside the fixing rotator;
A pressure rotator that forms a nip with the nip forming member via the fixing rotator; and
A fixing device including a support member that receives pressure applied to the nip forming member,
A shielding member movable between the inner surface of the fixing rotator and the heat source;
The fixing device, wherein the shielding member is capable of contacting and separating from the support member. Having detection means for detecting the temperature of the shielding member;
The fixing device according to claim 2, wherein the shielding member is capable of contacting and separating from the support member based on detection information of the detection unit. Detecting means for detecting the temperature of the fixing rotator,
The fixing device according to claim 2, wherein the shielding member is capable of coming into contact with and separating from the support member based on detection information of the detection unit. The shielding member has at least one notch shape,
5. The fixing device according to claim 1, wherein the shielding member shields the unnecessary portion of the fixing rotator by the notch shape so that the heat source does not heat the unnecessary portion. 6. .   The fixing device according to claim 1, wherein the shielding member is in direct contact with the support member.   The fixing device according to claim 1, wherein the shielding member is in contact with the support member via a heat transfer member.   An image forming apparatus comprising the fixing device according to claim 1.

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