JP5822114B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that fixes a toner image formed on a recording medium, and an image forming apparatus such as a copying machine, a facsimile, and a printer including the fixing device.

  Conventionally, in an image forming apparatus, a fixing device that fixes a toner image on a recording paper by applying heat and pressure to a recording medium such as a recording paper carrying an unfixed toner image has been widely used. As one of them, recording is performed by press-contacting a rotatable endless belt member that can rotate, a roller member that can be rotationally driven to press contact with the outer peripheral surface of the belt member, and a roller member that is rotationally driven via the belt member. A configuration including a nip forming member that forms a nip through which paper is conveyed and a heating unit that heats a belt member from the inside is known. Further, a heating element such as a halogen heater is widely used as the heating means.

  Further, the image forming apparatus is required to cope with various recording papers, and it is desired that papers having various thicknesses and sizes can be used. In particular, there is an increasing demand for handling small-size paper having a paper width of about 100 mm, such as postcards and envelopes. However, in a fixing device having only a halogen heater corresponding to the maximum sheet passing width, the temperature rise in the non-sheet passing portion becomes large when small-size sheets are continuously fed, so that productivity must be reduced. It was a situation that had to be done.

  In order to solve the problem of temperature rise in the non-sheet passing portion, a plurality of heaters having different heat generation areas are provided, and the plurality of heaters are turned on / off so as to obtain a desired heating width corresponding to the width of the recording sheet to be passed. An apparatus for switching is known (for example, Patent Document 1). In addition, using an induction heating method, a heating member made of a magnetic shunt alloy whose Curie temperature is generally set to the fixing temperature is provided inside the belt member, and heat is generated in the heating member from the magnetic field generated by the magnetic flux generation unit, An apparatus for transmitting generated heat to a belt member is known (for example, Patent Document 2).

  However, an apparatus including a plurality of heaters having different heat generation areas requires the same number of heaters as the width of the recording paper to be passed, which increases the cost. In addition, in the apparatus using the induction heating method, the cost is significantly higher than the heating means using a heater.

  The present invention has been made in view of the above problems, and an object thereof is to provide a low-cost fixing device and an image forming apparatus that can suppress a temperature rise in a non-sheet passing portion.

In order to achieve the above object, the invention of claim 1 comprises a rotatable endless belt member having flexibility, a roller member that can be rotationally driven in pressure contact with the outer peripheral surface of the belt member, and the belt member. In the fixing device, comprising: a nip forming unit that forms a nip that is pressed against the roller member that is rotationally driven through the recording medium; and one or more heating elements that heat the belt member from the inside. At least two or more heating elements of the body, the predetermined region of the heat generating region in the width direction of the belt member have a center and the circumferentially directed the heating element, said two or more heating elements are directional is configured so that different from each other a predetermined region in the width direction with, and, is characterized in that the rotation control in accordance with the recording medium being the transport.

  In the present invention, a heat generating element having a directivity in the circumferential direction is used in a predetermined area of the heat generating area related to the width direction, and the heat generating element is rotationally controlled according to the recording medium to be conveyed, thereby controlling the width direction with respect to the belt member. Adjust the radiation intensity distribution. Specifically, the heat generating area of the heat generating element has a predetermined area corresponding to a non-sheet passing portion of a small size recording medium having directivity in the circumferential direction. When transporting small size paper, this heating element is rotated so that the peripheral surface capable of releasing heat does not face the belt member in a predetermined area corresponding to the non-sheet passing portion. As a result, when small-size paper passes, the heat released from the heating element is not radiated to the non-sheet passing portion of the belt member, and an excessive temperature rise in the non-sheet passing portion can be suppressed. Since the structure of the present invention can use an inexpensive heating element such as a halogen heater, the structure can be reduced in cost as compared with the apparatus using the induction heating method. In the configuration of the present invention, the heating width corresponding to the width of at least two types of recording media can be obtained with one heating element having the directivity. For this reason, compared to a device that uses the same number of heating elements as the width type of the recording medium to pass the sheet and suppresses the temperature rise of the non-sheet passing portion, the number of heating elements to the same type of recording medium can be reduced. Correspondence is possible. Therefore, the cost of the apparatus can be reduced.

  According to the present invention, there is an excellent effect that it is possible to provide a low-cost fixing device and an image forming apparatus that can suppress a temperature rise in a non-sheet passing portion.

1 is a schematic configuration diagram of a fixing device according to an embodiment. FIG. 3 is a configuration diagram inside a fixing belt of the present embodiment. It is explanatory drawing of the halogen heater of this embodiment, (a) is the figure which looked at the halogen heater from the side facing a fixing belt, (b) is an axial sectional view of a predetermined area. The cross-sectional enlarged view of a halogen heater. Explanatory drawing of rotation of a halogen heater and ON / OFF control in Example 1. FIG. Explanatory drawing of rotation and ON / OFF control of the halogen heater in Example 2. FIG. The perspective view of the halogen heater and pressurization stay of a modification. 1 is a schematic configuration diagram of an image forming apparatus according to an embodiment. 1 is a schematic configuration diagram of a conventional fixing device.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a fixing device 4 of the present embodiment. The fixing device 4 includes a pressure roller 41 that is a pressure member that is rotationally driven, and a fixing belt 42 that is a fixing member. In the fixing belt 42, a nip forming unit, which will be described later, and a first halogen heater 43a and a second halogen heater 43b as heating elements are provided. In this fixing device 4, a pressure belt 41 that is driven to rotate is driven by a fixing belt 42 pressed by a nip forming unit, and the recording paper is held by the nip formed between the fixing belt 42 and the pressure roller 41. Transport. Then, heat is applied to the toner on the recording paper from the surface of the fixing belt 42 heated by the first halogen heater 43a and the second halogen heater 43b, and the toner on the recording paper is fixed by the action of heat and pressure.

  The pressure roller 41 is obtained by providing an elastic layer made of silicone rubber on the surface of a hollow metal roller. Furthermore, a release layer (PFA or PTFE layer) having a layer thickness of 5 to 50 μm is provided on the surface in order to obtain release properties. The pressure roller 41 is rotated by a driving force transmitted through a gear from a driving source such as a motor (not shown) provided in the image forming apparatus. The pressure roller 41 is pressed against the fixing belt 42 by a spring or the like. The pressure roller 41 and the fixing belt 42 are pressed against each other, and the elastic layer is crushed and deformed to form a predetermined nip width. To do. The pressure roller 41 may be a solid roller, but a hollow roller may have a smaller heat capacity. The elastic layer may be solid rubber or sponge rubber. The use of sponge rubber is more desirable because heat insulation is enhanced and heat of the fixing belt 42 is hardly taken away.

  The fixing belt 42 is an endless belt member having flexibility. As the belt substrate, a metal belt such as nickel or SUS having a layer thickness of 30 to 50 μm, or an endless belt (or film) using a resin material such as polyimide is used. The surface layer of the fixing belt 42 has a release layer made of PFA or PTFE, and has a release property so that toner does not adhere. An elastic layer such as silicone rubber may be provided between the belt substrate and the release layer. When there is no elastic layer, the heat capacity is reduced and the fixability is improved, but when the unfixed image is crushed and fixed, subtle irregularities on the belt surface are transferred to the image, and a crusty skin-like mark is printed on the solid portion of the image. This causes a defect that remains. In order to improve this, it is preferable to provide an elastic layer of 100 μm or more such as silicone rubber. Due to the deformation of the elastic layer, subtle unevenness is absorbed and the skin image is improved.

  The fixing belt 42 is driven by a nip portion from a pressure roller 41 that is rotationally driven by a drive source (not shown), and rotates with the pressure roller 41. Outside the nip portion, it is guided by a holding member (not shown) that holds the fixing belt 42 from both ends, and the cross-sectional shape stably maintains a circular shape and rotates.

  The nip forming unit includes a nip forming member 44 that contacts the pressure roller 41 via the fixing belt 42, and a pressure stay 45 that supports the nip forming member 44.

  The nip forming member 44 slides directly with the inner peripheral surface of the fixing belt 42 or indirectly through a sliding sheet (not shown). Furthermore, sliding torque is reduced by applying a lubricant such as fluorine grease or silicone oil to the sliding sheet (not shown). As a result, the fixing belt 42 is stably brought to the pressure roller 41. In FIG. 1, the nip portion of the nip forming member 44 has a flat shape, but may have a concave shape or other shapes. In the case of the concave shape, the discharge direction of the leading edge of the sheet is from the pressure roller 41, the separability is improved, and jamming is suppressed.

  The pressure stay 45 has a sufficient bending strength to support the nip forming member 44 pressed by the pressure roller 41. As the material, a metal material such as stainless steel or iron, or a metal oxide such as ceramics is used.

  The first halogen heater 43a and the second halogen heater 43b as heating elements are arranged so that the three surfaces including the nip portion side are surrounded by the pressure stay 45 and the other surface faces the fixing belt 42. The first halogen heater 43a and the second halogen heater 43b are controlled in output (ON / OFF) by a power supply unit (not shown) of the apparatus main body, and heat the opposing fixing belt 42 by radiant heat. The heated fixing belt 42 moves to the nip portion by rotation and applies heat to the toner on the recording paper.

  Further, as shown in FIG. 1, a reflecting plate 46 may be provided on the inner peripheral surface of the pressure stay 45. The reflector 46 is used by polishing the surface of a metal material into a mirror surface. The reflection plate 46 reflects the radiant heat emitted from the first halogen heater 43a and the second halogen heater 43b, thereby reducing the amount of heat flowing into the pressure stay 45 and improving the heating efficiency for the fixing belt 42.

  Next, the first halogen heater 43a and the second halogen heater 43b will be described in detail. FIG. 2 is a configuration diagram of the inside of the fixing belt of the present embodiment. 3A and 3B are explanatory views of the halogen heater. FIG. 3A is a view of the halogen heater as viewed from the side facing the fixing belt 42, and FIG. 3B is an axial sectional view of a predetermined region. FIG. 4 is an enlarged cross-sectional view of the halogen heater.

  As shown in FIG. 3A, the first halogen heater 43a has a heat generating region in the central portion a in the width direction. A reflective film 47a is applied to the outer peripheral surface of a predetermined region at both ends in the width direction of the heat generating region in a range of 180 ° with respect to the circumferential direction. In addition, the second halogen heater 43b is a peripheral portion b excluding the heat generation region of the first halogen heater 43a. A reflective film 47b is applied to the outer peripheral surface of a predetermined region at both ends in the width direction of the heat generating region in a range of 180 ° with respect to the circumferential direction. FIG. 3B is an axial sectional view of each of the first halogen heater 43a and the second halogen heater 43b in a predetermined region. As described above, the first halogen heater 43a and the second halogen heater 43b cover the heating width with respect to the maximum sheet passing width, and the reflective film is in a predetermined region different in the width direction within a range of 180 ° with respect to the circumferential direction. 47a and b are applied. In the 180 ° range where the reflective films 47a and b are applied, the heat released from the halogen heater is reflected by the reflective films 47a and b, thereby reducing the radiant heat to the facing surface. That is, the first halogen heater 43a and the second halogen heater 43b have directivities in which heat is radiated only in a range of 180 ° in the circumferential direction in mutually different predetermined regions in the width direction.

  In the present embodiment, as shown in the enlarged view of FIG. 4, each halogen heater 43 is coated with the reflective film 47 in a range of 180 ° with respect to the circumferential direction, but is not limited thereto. The angle at which the reflective film 47 is applied may be changed. If the directivity (radiation range) is further narrowed, the angle is increased. If the directivity (radiation range) is increased, the angle is decreased. As a material of the reflective film 47, it is preferable to use a metal such as gold or aluminum and to make the surface a mirror surface.

  The first halogen heater 43a and the second halogen heater 43b are rotatably provided, respectively, and the outer peripheral surface on which the reflection films 47a and 47b are formed can be stopped at an arbitrary position in the circumferential direction.

  As described above, the first halogen heater 43a and the second halogen heater 43b having no directivity in the circumferential direction in a predetermined region in the width direction are used, and their rotation and ON / OFF are controlled so that the fixing belt 42 is moved in the width direction. Can be adjusted to have a radiant heat intensity distribution. By utilizing this, the radiant heat intensity to the non-sheet passing portion is reduced to suppress the temperature rise of the non-sheet passing portion. Hereinafter, specific description will be given based on examples.

<Example 1>
In Example 1, the light emission area of the first halogen heater 43a and the second halogen heater 43b, the area where the reflective film is applied, and the rotation and ON / OFF control are combined to form a postcard, A4 length, A4 width, 13 inches 4 The heating width corresponding to the type of paper width is realized.

  FIGS. 5A to 5D are explanatory diagrams of the first halogen heater 43a, the second halogen heater 43b, and rotation and ON / OFF control for each recording paper size. FIG. 5 shows a view of each halogen heater as viewed from the side facing the fixing belt 42 and an axial sectional view of a predetermined region, as in FIG. In addition, ON of the halogen heater is indicated by a solid line, and OFF is indicated by a dotted line.

  The first halogen heater 43a has a light emitting area of A4 vertical width, and coats the reflective film 47a in a range of 180 ° in the circumferential direction on the outer peripheral surface from both ends of the light emitting area of A4 vertical width to the postcard size width. The second halogen heater 43b has a light emitting area of 13 inches wide excluding the A4 vertical width, and applies the reflective film 47b in a range of 180 ° in the circumferential direction on the outer peripheral surface from both ends of the light emitting area to the A4 horizontal width.

  FIG. 5A shows a case where a postcard is passed, and the first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflection film 47a faces the side facing the fixing belt 42 (left side in the sectional view). The 2-halogen heater 43b is turned off. In this state, the first halogen heater 43a has a light emitting area having an A4 vertical width, but the heat at the end is reflected by the reflective film 47a, and heat is applied only to the necessary postcard size width, not the A4 vertical width. Radiated. Thereby, the non-sheet passing portion of the fixing belt 42 is not heated.

  FIG. 5B shows a case where A4 vertical paper is passed, and the first halogen heater 43a is turned on by rotating the reflective film 47a so that the reflective film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is turned off. In this state, the first halogen heater 43a radiates heat from the entire width of the A4 vertical light emitting region. As a result, the fixing belt 42 is heated to the required A4 vertical width.

  FIG. 5C shows a case where 13 inches are passed. The first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflective film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is turned on by rotating the second halogen heater 43b so that the reflective film 47a faces the side not facing the fixing belt 42 (right side in the cross-sectional view). In this state, both the first halogen heater 43a and the second halogen heater 43b radiate heat over the entire width of the light emitting region, and thereby radiate heat from the necessary 13 inch full width. As a result, the necessary 13 inch full width of the fixing belt 42 is heated.

  FIG. 5D shows a case where A4 paper is passed, and the first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflection film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is turned on by rotating the second halogen heater 43b so that the reflective film 47a faces the side facing the fixing belt 42 (left side in the sectional view). In this state, the first halogen heater 43a radiates heat over the entire width of the A4 vertical light emitting region. On the other hand, as for the second halogen heater 43b, the heat at the end is reflected by the reflective film 47b in the light emitting region, and the heat is radiated only to the necessary A4 lateral width together with the first halogen heater 43a. Thereby, the non-sheet passing portion of the fixing belt 42 is not heated.

  In this embodiment, two halogen heaters, the first halogen heater 43a and the second halogen heater 43b, are used, and the paper width is assumed to be four types of postcard, A4 length, A4 width, and 13 inches. In this configuration, a halogen heater can be used as the heating element, so that a low-cost configuration can be achieved. Moreover, there is no restriction | limiting in particular in the number of halogen heaters, and the assumed paper width, These combinations can be performed freely. For example, even if only one halogen heater is used, the radiation intensity distribution corresponding to the paper type is adjusted by controlling the facing relationship between the fixing belt 42 and the surface coated with the reflective film by rotating the halogen heater depending on the paper type. Necessary heating width can be obtained. Since this configuration can realize the heating width corresponding to each size with a small number of heating elements, compared to the configuration including all the heating elements having the heating width corresponding to each size, the cost can be reduced. Further, it has been experimentally confirmed that if the light shielding rate is about 50%, the effect of suppressing the temperature rise can be expected. Therefore, by providing reflective films having different lengths in the axial direction by 120 ° or 90 °. A single heater can correspond to three or four types of paper sizes.

<Example 2>
In the second embodiment, in addition to the configuration of the first embodiment, a reflective film is applied in addition to the light emitting areas of the first halogen heater 43a and the second halogen heater 43b, and radiation is emitted from the other halogen heater using this reflective film. To block the heat generated. Thereby, the required heating width is obtained by adjusting the radiation intensity distribution corresponding to the paper type more accurately.

  6A to 6D are explanatory diagrams of the first halogen heater 43a, the second halogen heater 43b, and rotation and ON / OFF control with respect to the recording paper size. FIG. 6 shows a view of each halogen heater as viewed from the side facing the fixing belt 42 and an axial sectional view of a predetermined region, as in FIG. In addition, ON of the halogen heater is indicated by a solid line, and OFF is indicated by a dotted line. In the following description, new points of the second embodiment will be mainly described, and the rest will be based on the first embodiment.

  The first halogen heater 43a is provided on the outer peripheral surface of both end portions in the width direction outside the light emitting region, in addition to the reflective film 47a in the range of 180 ° on the outer peripheral surface from the both end portions of the A4 vertical light emitting region to the postcard size width. The reflective film 48a is applied in a 180 ° range opposite to the range where the reflective film 47a is provided. The second halogen heater 43b has a reflection film 47b on the outer peripheral surface of the A4 vertical end outside the light emitting region, in addition to the reflective film 47b in the range of 180 ° on the outer peripheral surface from both ends of the light emitting region to the A4 horizontal width. The reflective film 48b is applied in the same 180 ° range as that in which the film is provided.

  FIG. 6A shows a case where a postcard is passed, and the first halogen heater 43a is turned on by rotating the reflective film 47a so that the reflective film 47a faces the side facing the fixing belt 42 (left side in the sectional view). The two-halogen heater 43b is turned off by rotating so that the reflection films 47b and 48ba face the first halogen heater 43a (upper side in the figure). In this state, as described above, the first halogen heater 43a has a light emitting area with A4 vertical width, but the heat at the end is reflected by the reflective film 47a, and not the A4 vertical width but the necessary postcard size. Heat is radiated only to the width. Furthermore, since heat other than the necessary postcard size width is also reflected by the reflective film 48b of the second halogen heater 43b, the non-sheet passing portion of the fixing belt 42 is hardly heated.

  FIG. 6B shows a case where A4 lengthwise paper is passed. The first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflective film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is turned off by rotating the second halogen heater 43b so that the reflecting films 47b and 48b face the side facing the fixing belt 42 (left side in the cross-sectional view).

  FIG. 6C shows a case of passing 13 inches. The first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflection film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is also turned on by rotating the second halogen heater 43b so that the reflection films 47b and 48b face the side not facing the fixing belt 42 (the right side in the sectional view).

  FIG. 6D shows a case where A4 paper is passed, and the first halogen heater 43a is turned on by rotating the first halogen heater 43a so that the reflective film 47a faces the side not facing the fixing belt 42 (right side in the sectional view). The second halogen heater 43b is turned on in a direction inclined by 45 ° from the side not facing the fixing belt 42 (right side in the sectional view).

  In Examples 1 and 2, a reflective film is provided in the range of 180 ° in the circumferential direction of the halogen heater so as to have directivity, but the directivity is combined with other parts arranged in the fixing belt. It can also be made to have. Hereinafter, a description will be given based on modifications.

<Modification>
In the modified example, the pressure stay 45 is provided with one or a plurality of slits so as to expect a light shielding effect equivalent to that of the reflection film of the halogen heater. By providing unevenness in the shape of the pressure stay 45 in the longitudinal direction, it is possible to locally block the radiant heat from the halogen heater.
FIG. 7 is a perspective view of a halogen heater and a pressure stay according to a modification. The portion 49 cut in the slit shape allows heat to be applied to the surface of the fixing belt 42 by allowing the radiant heat from the halogen heater 43 to pass through. However, the pressure stay 45 absorbs heat in the portion not cut by the slit. Thus, the inflow of heat to the surface of the fixing belt 42 can be prevented. Since the parameters relating to the light shielding effect are the slit width and the slit height, by adjusting these parameters, it is possible to suppress the excessive temperature increase on the surface of the fixing belt 42 and maintain the productivity of an arbitrary paper size. Further, when combined with the light shielding by the reflection film of the halogen heater 43 described above, a further light shielding effect can be expected.

  As a comparative example, FIG. 9 shows a schematic view of an example of a fixing device using a conventional belt member. The fixing device 5 of FIG. 9 is provided with a pressure roller 51 as a pressure member and a fixing belt 52 as a fixing member. The fixing belt 52 is stretched around a heating roller 55 and a nip forming roller 54 as a nip forming unit and rotates. A halogen heater 53 is provided inside the heating roller 55. In the fixing device 5, the recording paper is nipped and conveyed by a nip formed by the fixing belt 52 and the pressure roller 51. Then, heat is applied to the toner on the recording paper from the surface of the fixing belt 52 heated by the halogen heater 53 via the heating roller 55, and the toner on the recording paper is fixed by the action of heat and pressure. In the fixing device 5, there is a problem that the temperature of the non-sheet passing portion of the fixing belt 52 excessively rises during continuous passage of small size paper.

  Next, an example of an image forming apparatus that employs the fixing device 4 will be described. FIG. 7 is a schematic configuration diagram of an image forming apparatus according to an embodiment of the present invention. As shown in FIG. 7, this image forming apparatus is an intermediate that is an image carrier on which a color toner image composed of a plurality of colors of yellow (Y), cyan (C), magenta (M), and black (K) is formed. The intermediate transfer belt 1 serving as a transfer member and toner bottles 2Y, 2C, 2M, and 2K that replenish each color toner for color toner images are accommodated in the image forming apparatus main body. The intermediate transfer belt 1 is rotatably stretched by a tension roller 1a, an intermediate transfer belt drive roller 1b, and the like, and the intermediate transfer belt 1 is also illustrated by rotating the intermediate transfer belt drive roller 1b counterclockwise in the drawing. Rotates counterclockwise.

  Further, the image forming apparatus conveys the recording paper S loaded and stored in the paper feed tray 8 at the lower part of the image forming apparatus main body to a secondary transfer position facing the intermediate transfer belt 1 at a predetermined timing. The color toner image on the transfer belt 1 is transferred to the recording paper S, the color toner image on the recording paper S is fixed, and the fixed recording paper S is discharged from above. That is, the sheet feeding roller 7 that feeds one sheet of recording paper S, the registration roller pair 6 that secures the conveyance timing for transferring the toner image, and the intermediate transfer belt 1 are in contact with each other from the lower part to the upper part of the apparatus. A secondary transfer roller 5 in which a secondary transfer nip is formed between the intermediate transfer belt 1 and opposed to the intermediate transfer belt drive roller 1b, and a predetermined pressure is secured. A fixing device 4 that heats and pressurizes the recording medium. A pair of paper discharge rollers 3 for discharging S to the outside of the apparatus is arranged, and in the process of transporting the recording paper S along the transport path formed by these rollers and rollers, in the middle by the secondary transfer nip sequentially. The toner image is transferred from the transfer belt 1, and the toner image transferred onto the recording paper S by the fixing device 4 is fixed.

  The process cartridges 101Y, 101C, 101M, and 101K are slanted to the left in the figure as image stations, which are four color image forming units that are responsible for each color for forming a color image and form a toner image of that color. The intermediate transfer belt 1 is disposed along the longitudinal direction of the intermediate transfer belt 1. Each image station including these process cartridges 101Y, 101C, 101M, and 101K has photosensitive drums 21Y, 21C, 21M, and 21K as image carriers.

  Further, the photosensitive drums 21Y, 21C, 21M, and 21K are in contact with the primary transfer rollers 11Y, 11C, 11M, and 11K through the intermediate transfer belt 1 with a predetermined pressure. Around the photosensitive drums 21Y, 21C, 21M, and 21K, dedicated charging devices 15Y, 15C, 15M, and 15K, developing devices 10Y, 10C, 10M, and 10K as developing units, and cleaning for cleaning the photosensitive members, respectively. And photosensitive member cleaning devices 14Y, 14C, 14M, and 14K as means.

  Below the process cartridges 101Y, 101C, 101M, and 101K, there is arranged a writing unit 9 that writes the electrostatic latent image by exposing the surface of each of the photosensitive drums 21Y, 21C, 21M, and 21K with laser light. .

  A belt cleaning device 12 that is a cleaning unit that collects and cleans residual toner on the intermediate transfer belt 1 is stretched through the intermediate transfer belt 1 on one end side in the longitudinal direction of the intermediate transfer belt 1. It is provided to face the gantry roller 1a.

  A plurality of toner bottles 2Y, 2C, 2M, and 2K that supply toner to the developing devices 10Y, 10C, 10M, and 10K are sequentially arranged from the left side to the right side in the drawing in the upper part of the apparatus, and are disposed on the main body of the image forming apparatus. It is provided to be detachable and replaceable. Each of the plurality of toner bottles 2Y, 2C, 2M, and 2K is filled with toners of yellow, cyan, magenta, and black, respectively. The toner bottles 2Y, 2C, 2M, and 2K are connected to each color developing device 10Y, 10C, 10M, and 10K corresponding to the toner bottles 2Y, 2C, 2M, and 2K through a conveyance path (not shown) so that toner can be supplied. The toner of each color is replenished by a predetermined replenishment amount.

  In the image forming apparatus configured as described above, when the recording paper S is fed by the paper feed roller 7 and the leading edge reaches the registration roller pair 6, the leading edge of the recording paper S is detected by a sensor (not shown). Then, the recording paper S is conveyed to the nip formed by the secondary transfer roller 5 and the intermediate transfer belt 1 by the registration roller pair 6 while taking the synchronization timing based on the detection signal, and the recording paper S is transferred from the intermediate transfer belt 1 to the recording paper S. The image formed on the intermediate transfer belt 1 is secondarily transferred.

  The photosensitive drums 21Y, 21C, 21M, and 21K are uniformly charged in advance by the charging devices 15Y, 15C, 15M, and 15K, and then laser light is exposed and scanned by the writing unit 9 based on the image data. Electrostatic latent images are created on 21Y, 21C, 21M, and 21K. The electrostatic latent images are developed by the developing devices 10Y, 10C, 10M, and 10K for the respective colors, thereby forming yellow, cyan, magenta, and black toner images on the surfaces of the photosensitive drums 21Y, 21C, 21M, and 21K. Is done. Next, a voltage is applied to the primary transfer rollers 11Y, 11C, 11M, and 11K, and the toner on the photosensitive drums 21Y, 21C, 21M, and 21K is sequentially transferred onto the intermediate transfer belt 1. At this time, the image forming operation of each color is shifted in timing from the upstream side to the downstream side in the feeding direction of the intermediate transfer belt 1 so that the toner image is transferred to the same position on the intermediate transfer belt 1. Executed. The toner image formed on the intermediate transfer belt 1 is transported to the secondary transfer position where the secondary transfer roller 5 faces and is secondarily transferred to the recording paper S. The recording sheet S on which the color toner image of each color is transferred is conveyed to the fixing device 4, where the toner image is fixed by pressure and heat, and is discharged by the discharge roller pair 3.

What has been described above is merely an example, and the present invention has a specific effect for each of the following modes.
(Aspect A)
The endless belt member having flexibility such as the fixing belt 42 and the like, the roller member such as the pressure roller 41 that can be rotationally driven in pressure contact with the outer peripheral surface of the belt member, and the belt member are rotated. Heat generation of a nip forming means including a nip forming member 44 and a pressure stay 45 that form a nip that is pressed against the roller member to convey the recording medium, and one or more halogen heaters 43 that heat the belt member from the inside. The fixing device 4 includes a body. In the fixing device 4, at least one of the heat generating members has directivity in a circumferential direction centering on the heat generating member in a predetermined region of the heat generating region with respect to the width direction of the belt member. The rotation is controlled according to According to this, as described in the above embodiment, it is possible to provide a low-cost fixing device that can suppress the temperature rise of the non-sheet passing portion.
(Aspect B)
In (Aspect A), the heating element such as the halogen heater 43 has directivity by applying the reflective film 47 to any region in the circumferential direction of the outer peripheral surface. According to this, as described in the above embodiment, the heating element has directivity in the circumferential direction around the heating element with respect to the predetermined area of the heating element in the width direction of the belt member by simple means. Can be formed.
(Aspect C)
In (Aspect A) or (Aspect B), the first halogen heater 43a and the second halogen heater 43b are provided with a plurality of directional heating elements, and the plurality of heating elements have a directional predetermined region in the width direction. Different from each other. According to this, as described in the above embodiment, a necessary heating width can be obtained with a small number of heating elements corresponding to various sizes.
(Aspect D)
In (Aspect C), a plurality of directional heating elements such as the first halogen heater 43a and the second halogen heater 43b are provided, and the heating areas of the plurality of heating elements are different from each other in the width direction. According to this, as described in the above embodiment, a necessary heating width can be obtained with a small number of heating elements corresponding to various sizes.
(Aspect E)
In (Aspect C) or (Aspect D), a plurality of directional heating elements such as the first halogen heater 43a and the second halogen heater 43b can be independently controlled in rotation. According to this, as described in the above embodiment, a necessary heating width can be obtained with a small number of heating elements corresponding to various sizes.
(Aspect F)
In the fixing device of (Aspect A), a slit is provided in a support member such as a pressure stay 45 that supports the nip forming member 44, and heating elements such as the first halogen heater 43a and the second halogen heater 43b are surrounded by the support member. By arrange | positioning in this way, a heat generating body has directivity. According to this, as described in the modification, the heating element has directivity in the circumferential direction around the heating element with respect to the predetermined area of the heating element in the width direction of the belt member by simple means. Can be formed.
(Aspect G)
In the image forming apparatus employing the fixing devices of (Aspect A) to (Aspect F), as described in the above embodiment, it is possible to provide a low-cost image forming apparatus that can suppress a temperature rise in the non-sheet passing portion.

4 Fixing Device 41 Pressing Roller 42 Fixing Belt 43 Halogen Heater 43a First Halogen Heater 43b Second Halogen Heater 44 Nip Forming Member 45 Pressing Stay 46 Reflecting Plate 47a Reflecting Film (In Heating Area of First Halogen Heater)
47b Reflective film (in the heat generation area of the second halogen heater)
48a Reflective film (outside heat generation area of first halogen heater)
48b Reflective film (outside heat generation area of second halogen heater)

JP 2007-206507 A Japanese Patent No. 2975435

Claims (5)

An endless belt member having flexibility that can rotate, a roller member that can be rotationally driven in pressure contact with the outer peripheral surface of the belt member, and a roller that is rotationally driven via the belt member to press the recording medium. In a fixing device including a nip forming member that forms a nip to be conveyed and one or more heating elements that heat the belt member from the inside,
At least two or more heating elements of the heating element, the predetermined region of the heat generating region in the width direction of the belt member have a directivity in the circumferential direction centering the heating element, said two or more heating elements predetermined region having directivity is configured so that different from each other in the width direction, and a fixing device, characterized in that the rotation control in accordance with the recording medium being the transport. 2. The fixing device according to claim 1, wherein the heating element has directivity by applying a reflection film to an arbitrary region in the circumferential direction of the outer peripheral surface . 3. The fixing device according to claim 1, wherein the heat generating regions of the plurality of heating elements are different from each other in the width direction. 4. The fixing device according to claim 1, wherein the plurality of heating elements can be independently controlled to rotate . Image forming means for forming an unfixed image on a record medium, an image forming apparatus and a fixing unit that allowed to fix the yet-fixed image on the recording medium, as the fixing means, according to claim 1 to 4 An image forming apparatus using any one of the fixing devices.

Images