JP6606746B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

  The present invention relates to a fixing device that fixes toner on a sheet by thermal fixing, and an image forming apparatus including the fixing device.

  The fixing device includes, for example, a first rotating body for heating and a second rotating body for pressurization. For example, a halogen heater is incorporated in the first rotating body as a heat source. The second rotating body is an elastic roller, and generally includes an elastic layer that covers the peripheral surface of the steel pipe. Such a second rotating body is pressed against the first rotating body and elastically deforms, whereby a nip is formed at a contact portion between both rotating bodies.

  The elastic layer is typically made of silicon rubber. Silicone rubber is heated by a heat source during heat fixing, and thus generates low-molecular siloxane that is ultrafine particles (UFP). Also, UFP may occur from the toner on the sheet. In order to collect such UFP, various methods have been conventionally proposed (see, for example, Patent Document 1).

JP 2010-134133 A

  In addition to the method described in Patent Document 1, during heat fixing, image formation in which air in the fixing device is sucked with a fan from above and UFP is separated from the sucked air and collected using a filter. There is also a device. However, according to this configuration, since air is sucked from above in the fixing device, UFP can be collected efficiently, but the thermal fixing temperature (that is, the temperature of the first rotating body) is lowered.

  The image forming apparatus may include a thermistor that detects the temperature of the first rotating body in a non-contact manner. If the fan sucks air during heat fixing, the ambient temperature of the thermistor decreases, so the detected temperature of the thermistor may not accurately represent the actual heat fixing temperature. Therefore, it is necessary to arrange the thermistor in a place not affected by air suction. Otherwise, it has been necessary to suck the air rising above the fixing device from the side (that is, the axial direction of each rotating body) with a fan and collect it with a filter. According to this method, since the air in the fixing device is not sucked, a reduction in fixing temperature can be suppressed. However, there is a difficulty in securing a space for arranging ducts and UFP collection efficiency.

  SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a fixing device capable of suppressing a decrease in thermal fixing temperature and an image forming apparatus using the same.

One aspect of the present invention is a fixing device, which includes a plurality of rotating bodies that fix toner on a sheet by heat fixing, covers each of the rotating bodies, and has a first opening above and below each of the rotating bodies. An exterior body having a second opening, wherein the exterior body retains ultrafine particles in the space facing the plurality of rotating bodies during the thermal fixing, and the first opening after completion of the thermal fixing. top of the first blowing means for performing suction of the peripheral region of said first opening from above, a first collecting means for collecting separated ultrafine particles from the intake of the first blowing means, of the thermal fixing A second air blowing means for sucking in the peripheral area of the second opening from below the second opening and retaining ultrafine particles in the exterior body, and during the heat fixing The second air blowing means sucks air stronger than the first air blowing means, but the heat After the wearing completion of the first blowing means performs suction stronger than the second blowing means.

  Another aspect of the present invention is directed to an image forming apparatus including the fixing device.

  According to each of the above aspects, the intake by the first air blowing means is performed from above the first opening, but is performed after the end of thermal fixing. As a result, it is not always necessary for the first air blowing means to perform intake during the heat fixing. Therefore, it is possible to provide a fixing device capable of suppressing a decrease in the thermal fixing temperature and an image forming apparatus including the fixing device.

1 is a diagram illustrating a configuration of an image forming apparatus. FIG. 2 is a diagram illustrating a detailed configuration of the fixing device in FIG. 1. It is a figure which shows adjustment of the area of the 1st opening part of FIG. FIG. 2 is a main flowchart showing the operation of the fixing device of FIG. 1. It is a flowchart which shows the detailed operation | movement in S03 of FIG. It is a schematic diagram which shows the air flow in the middle of heat fixing. It is a flowchart which shows the detailed operation | movement of S05 of FIG. It is a figure which shows the effect of the image forming apparatus of FIG. FIG. 3 is a diagram illustrating another configuration example of the fixing device in FIG. 1. It is a figure which shows the 1st opening part shown in FIG.

<Embodiment>
Hereinafter, an image forming apparatus according to an embodiment and a fixing device included in the image forming apparatus will be described in detail with reference to the drawings.

<< First column: Definition >>
In some drawings, an x-axis, a y-axis, and a z-axis are shown. The x axis indicates the horizontal direction of the image forming apparatus 1 and the fixing device 5. The y axis indicates the front-rear direction of the image forming apparatus 1 and the fixing device 5. The z axis indicates the vertical direction of the image forming apparatus 1 and the fixing device 5.

<< Second column: Configuration and operation of image forming apparatus >>
First, refer to FIG. The image forming apparatus 1 is, for example, a copying machine, a printer, a facsimile machine, or a multifunction machine having these functions, and prints a full color image on a sheet S (for example, paper or OHP film) by, for example, a tandem method. To do. Such an image forming apparatus 1 generally includes a supply unit 2, a timing roller pair 3, an image forming unit 4, a fixing device 5, a discharge tray 6, and a control circuit 7.

  The supply unit 2 sends out the sheets S one by one to a conveyance path (hereinafter, referred to as a conveyance path α) indicated by a dashed arrow α. The sheet S is transported on the transport path α and abuts against the timing roller pair 3 that is stopped. Thereafter, the timing roller pair 3 starts to rotate at a predetermined timing, and sends the sheet S to a secondary transfer region 43 described later.

  In the image forming unit 4, a toner image of a corresponding color is formed on the peripheral surface of the photosensitive drum 41 for Y (yellow), M (magenta), C (cyan), and K (black) by a known electrophotographic method. It is formed. Each toner image is sequentially transferred to the same area of the intermediate transfer belt 42 that rotates in the direction of arrow β (primary transfer), whereby a full-color composite toner image is formed on the intermediate transfer belt 42. The synthesized toner image is conveyed toward the secondary transfer region 43 while being carried on the intermediate transfer belt 42.

  In the secondary transfer region 43, the composite toner image on the intermediate transfer belt 42 is transferred to the sheet S introduced from the timing roller pair 3 (secondary transfer), and then the composite toner image is conveyed as an unfixed sheet S. It is sent out downstream of the path α (that is, toward the fixing device 5).

  The fixing device 5 includes a first rotating body 51 and a second rotating body 52. The rotating bodies 51 and 52 are in contact with each other to form a nip 53 and are rotated by a driving force from a motor (not shown). In the present embodiment, it is assumed that the driving force is supplied to the rotating body 52 and the rotating body 51 rotates following the rotation of the rotating body 52.

  An unfixed sheet S is introduced into the nip 53. The unfixed sheet S passing through the nip 53 is pressed by both the rotating bodies 51 and 52 and heated by a heat source 54 built in the rotating body 51 (hereinafter referred to as a fixing process). As a result, the synthetic toner image on the unfixed sheet S is fixed. The fixed sheet S is sent out from the nip 53 to the downstream side of the transport path α and is finally discharged to the discharge tray 6.

  The control circuit 7 includes a CPU, a ROM, and a RAM, and controls each part of the image forming apparatus 1.

<< Third column: Detailed configuration of fixing device >>
In addition to the rotating bodies 51 and 52 and the heat source 54, the fixing device 5 includes a temperature detecting means 55, an exterior body 56, a first air blowing means 57, a first collecting means 58, as illustrated in FIG. Second air blowing means 59 and second collecting means 510 are provided.

The rotating body 51 is, for example, a roller having an outer diameter of about 30 mm (more specifically, a roller in which an aluminum tube having a thickness of about 0.6 mm is covered with a coating layer having a thickness of about 20 μm).
The rotating body 52 is, for example, a roller having an outer diameter of about 30 mm and a hardness of about 45 ° (more specifically, an iron cored bar having an outer diameter of about 16 mm and a silicon sponge having a thickness of about 7.0 mm). And a roller coated with a PFA tube having a thickness of about 30 μm.

The rotating body 52 is elastically deformed by being pressed by the rotating body 51 with a predetermined load, and a nip 53 that forms a passage region of the sheet S is formed at a contact portion between the rotating bodies 51 and 52. An example of detailed specifications of the nip 53 is as follows.
・ Nip load: about 120N
-Nip width (the length in the conveying direction of the sheet S): about 4.0 mm
・ Nip length (length in the front-rear direction): about 320 mm

The heat source 54 is built in the rotating body 51 and includes, for example, a side heater 54a and a center heater 54b. These are all halogen heaters, and examples of the detailed specifications thereof are as follows.
・ Power consumption of side heater 54a: about 520W
-Light emission length of side heater 54a: 90 mm to 145 mm from both ends
-Power consumption of the center heater 54b: about 780W
-Light emission length of the center heater 54b: about 90 mm forward and backward from the center in the front-rear direction

  The side heater 54 a mainly heats portions of about 90 mm to 145 mm from the front end and the rear end of the sheet S passing region (that is, the front side and the rear side of the nip 53). On the other hand, the center heater 54b mainly heats a portion of about 90 mm from the center of the passage region of the sheet S to the front and rear (that is, the central portion of the nip 53).

The temperature detection means 55 detects the temperature of the rotating body 51. In the present embodiment, for example, the temperature detection unit 55 includes a side thermistor 55a and a center thermistor 55b. The side thermistor 55a detects the temperature of a portion of about 125 mm forward or backward (that is, the front end side or the rear end side of the rotating body 51) in a non-contact manner with respect to the center in the front-rear direction of the rotating body 51. The center thermistor 55b detects the temperature of a portion of about 30 mm forward or backward from the center of the rotator 51 in the front-rear direction without contact. The control circuit 7 controls the temperature of the rotating body 51 (that is, the thermal fixing temperature) to, for example, 180 ° C. based on the temperature information detected by the temperature detecting means 55.

  The exterior body 56 is a box that houses the rotating bodies 51 and 52 and the temperature detection means 55. A first opening 56a and a second opening 56b serving as a discharge port and a carry-in port for the sheet S are formed on the upper surface and the bottom surface of the outer package 56 (that is, above and below the nip 53). The sheet S is guided from the opening 56b to the nip 53, and after passing through the nip 53, is discharged from the opening 56a. Further, the openings 56a and 56b are also used for air suction by the air blowing means 57 and 59 described later.

  In the exterior body 56, several guide members that define the transport path α are provided. In particular, the guide member 56c is configured to define a section from the nip 53 to the opening 56a in the transport path α, and to change the opening area of the opening 56a under the control of the control circuit 7. Specifically, the guide member 56c is configured to be rotatable in the zx plane as a center provided in the vicinity of the lower end thereof and parallel to the front-rear direction.

  In addition, an accommodation unit 56 d is provided in the internal space of the exterior body 56. The accommodating means 56d has, for example, substantially the same length in the front-rear direction as the rotating body 51, and is disposed along the rotating body 51 immediately beside it. Further, an opening 56e is formed in the accommodating means 56d at a position P1 facing the rotating body 51. From this opening 56e, UFP generated during the thermal fixing is taken into the internal space of the accommodating means 56d.

  Both the air blowing means 57 and 59 are fans, for example, and perform intake under the control of the control circuit 7. The blower means 57 is provided on the downstream side of the exterior body 56 in the transport path α so as to face the peripheral region P2 of the opening 56a from above, and the air in the peripheral region P2 is set by the control circuit 7. Inhale with the amount of inspiration. On the other hand, the air blowing means 59 is provided in the peripheral area P3 of the opening 56b immediately upstream of the outer package 56 in the transport path α, and the air in the peripheral area P3 is set by the second intake air amount set by the control circuit 7. Aspirate.

  The collecting means 58 and 510 are, for example, air filters, and are attached to the exhaust ports of the air blowing means 57 and 59 to separate and collect UFP from the exhaust air of the air blowing means 57 and 59.

《Column 4: About the main part of the fixing device》
The image forming apparatus 1 essentially retains air (including UFP) in the exterior body 56 (more specifically, in the housing unit 56d) during the heat fixing, and after the heat fixing is finished. Then, the air staying in the exterior body 56 is sucked by the blowing means 57, and UFP is separated from the discharged air of the blowing means 57 by the collecting means 58 and collected. Therefore, it is desirable to prevent the stagnant air in the exterior body 56 from escaping outside the exterior body 56 as much as possible during heat fixing.

  The inventor of the present invention has made several contrivances in order to retain air in the exterior body 56. During heat fixing, the air in the outer package 56 is warmed and rises and tries to escape to the outside from the opening 56a. The present inventor first tried to make the area of the opening 56a smaller than the opening 56b during the heat fixing. Here, since the front-rear direction length of the openings 56a and 56b cannot be changed, in this embodiment, the width w of the opening 56a (see the upper part of FIG. 3) is as small as about 2.5 mm to 3.5 mm, for example. Is done.

  Further, the inventor of the present invention has caused convection in the direction opposite to the upward flow of the warmed air to occur inside the exterior body 56 during the heat fixing. In the present embodiment, the air blowing means 59 sucks the air in the peripheral region P <b> 3 below the exterior body 56, thereby generating convection to the extent that air stays inside the exterior body 56. Hereinafter, this convection will be described in more detail.

  In examining the implementation of the image forming apparatus 1, the inventor measured what kind of convection should be generated in the exterior body 56 in order to retain air inside the exterior body 56. Specifically, the following air blowing means 57 and 59 were prepared. That is, when the blowing means 57 and 59 are operated independently, the wind speed measured at the position P1 is set to v1 and v2 (see the upper part of FIG. 3). In this study, when only the air blowing means 57 is operated at the maximum output, the wind speed v1max is obtained approximately 0.36 m / s (ie, +0.36 m / s) at the position P1, and only the air blowing means 59 is independent. The air blowing means 57 and 59 were prepared so that the wind speed v2max was about 0.24 m / s (that is, -0.24 m / s) downward at the position P1 when operated. As for the wind speeds v 1 and v 2, PWM signals having various duty ratios are supplied to the blowing means 57 and 59 under the control of the control circuit 7. The wind speeds v1 and v2 can be changed by adjusting the duty ratio of each input PWM signal. In this embodiment, the duty ratio can be set to any of 0/3, 1/3, 2/3, and 3/3. Under such conditions, the present inventor sets the duty ratio of the blowing means 57 and 59 to 1/3 and 3/3 during the thermal fixing, and the combined wind speed v at the position P1 is −0.1 m. It was set in the range of / s to -0.2 m / s, and thereby, it was confirmed that convection was generated in the outer package 56 and air was retained.

  Further, as shown in FIGS. 2 and 3, the internal space of the exterior body 56 (more specifically, the internal space of the accommodating means 56 d) is configured by a curved surface, and air is likely to stay inside the exterior body 56. did.

<Column 5: Operation of the fixing device>
Next, the operation of the fixing device 5 will be described mainly with reference to FIG.
First, when WU (warm-up) is started in the image forming apparatus 1, the control circuit 7 sets the temperature of the rotating body 51 to 180 ° C., which is an example of a target temperature, based on the temperature information from the temperature detection unit 55. (S01). Thereafter, the image forming apparatus 1 enters a standby mode and waits for the arrival of a print job (S02). In the WU and standby mode, the control circuit 7 supplies PWM signals with a duty ratio of 0/3 to the air blowing means 57 and 59 and does not operate them.

  When the print job arrives, the control circuit 7 prepares for a printing operation (S03). Hereinafter, the process of S03 will be described in detail with reference to FIG. In S03, the heat fixing temperature and the conveyance speed of the sheet S (the rotation speed of the rotating body 52, etc.) are set according to the conditions of the print job (S11, S12). Also, PWM signals having a duty ratio of 1/3 and 3/3 are supplied to the air blowing means 57 and 59. That is, the second intake amount is increased (S13). Furthermore, the area of the opening 56a (see the upper part of FIG. 3) is relatively reduced (S14).

  Reference is again made to FIG. Subsequent to S03, the printing operation as described in the second column is performed (S04). During the printing operation, the fixing device 5 performs thermal fixing. During heat fixing, ascending air current is generated in the exterior body 56 as shown in FIG. 6 due to heat generated by the rotating body 51 (see arrow γ). Moreover, since the air in the exterior body 56 and the rotating body 52 are also heated, UFP is generated from the rotating body 52. UFP is also generated from the toner image formed on the sheet S to be heat-fixed. Such a UFP rides in an ascending air current and travels toward the opening 56a on the upper surface of the exterior body 56. During the heat fixing, the area of the opening 56a is relatively small. Including) is difficult to escape to the outside of the exterior body 56. Therefore, much air flows in the left-right direction along the upper inner wall of the exterior body 56 (see arrow δ).

  Further, since the corners of the internal space of the exterior body 56 are configured with curved surfaces, the direction of airflow changes downward at the corners of the exterior body 56 (see arrow ε). Further, the downward air flow is promoted by the laminar flow of the rotating bodies 51 and 52. In this manner, downward convection with respect to the rising airflow is also generated in the internal space of the exterior body 56. Further, in the present embodiment, during the heat fixing, the air blowing means 59 sucks air stronger than the air blowing means 57 by setting the duty ratio in S03. This also causes downward convection. At this time, there is a possibility that the UFP may escape to the outside from the opening 56b, but the UFP is collected by the collecting means 510 after passing through the air blowing means 59.

  Since the specific gravity of the UFP is small, the UFP rides on the airflow and stays in the exterior body 56, and is accommodated in the accommodating means 56d in the process (see arrow ζ).

  Reference is again made to FIG. When the printing operation (thermal fixing) in S04 is completed, the control circuit 7 causes the printing operation to fall (S05). Hereinafter, the process of S05 will be described in detail with reference to FIG. In S05, the heating of the rotating body 51 and the conveyance of the sheet S are stopped (S21, S22). Also, PWM signals having a duty ratio of 3/3 and 0/3 are supplied to the air blowing means 57 and 59. That is, the first intake air amount is increased (S23). Further, the area of the opening 56a (see the lower part of FIG. 3) is relatively increased (S24).

  Reference is again made to FIG. Subsequent to S05, the image forming apparatus 1 performs post-processing (that is, collection of UFP) (S06). Specifically, as a result of S05, the laminar flow due to the rotation of the rotating bodies 51 and 52 is eliminated. Therefore, the UFP in the exterior body 56 is directed upward by the rising airflow. Furthermore, since the air blowing means 57 sucks air stronger than the air blowing means 59 by setting the duty ratio in S05, and the sheet S does not pass on the conveyance path α, the air blowing means 57 is disposed inside the exterior body 56, and Can suck the air in the accommodating means 56d through the opening 56a. The collecting means 58 takes in the exhaust air from the air blowing means 57 and separates and collects UFP.

  After the start of S06, the control circuit 7 performs the post-processing until the elapsed time from the start of the post-processing passes a predetermined time (for example, 60 seconds) (S07). Thereafter, the control circuit 7 stops supplying the PWM signals to both the air blowing means 57 and 59 to stop them (S08), determines whether or not to enter the sleep mode (S09), and determines Yes. Then, it shifts to the sleep mode. On the other hand, if it is determined No in S09, the control circuit 7 shifts to the standby mode (S02).

<Sixth column: Action and effect of fixing device>
In the fixing device 5, the UFP generated by the thermal fixing is retained in the exterior body 56 during the thermal fixing by the device described in the fourth column. Further, during the heat fixing, the first intake air amount of the air blowing means 57 is smaller than the second air intake amount of the air blowing means 59. In the present embodiment, the first intake air amount is zero during heat fixing. Therefore, since air does not escape to the outside of the exterior body 56, it is possible to suppress a decrease in the heat fixing temperature.

In order to confirm the effect of the image forming apparatus 1, the present inventor prepared the following three types of image forming apparatuses, that is, a comparative example, an evaluation machine A, and an evaluation machine B.
Comparative example: all main parts (see the fourth column) and post-processing (see the fifth column) are removed from the image forming apparatus 1 Evaluation machine A: the post-processing is removed from the image forming apparatus 1 (However, the main part of the fourth column is provided)
Evaluation machine B: the image forming apparatus 1 itself

  The present inventor causes the above-mentioned comparative example and the evaluation machines A and B to execute print jobs under the same conditions, and the time of the number of UFPs per unit volume (that is, UFP concentration) in the peripheral region P2 (see FIG. 2) Changes were measured. In the comparative example, as shown in the upper part of FIG. 8, the UFP density increases with the passage of time from the start of the printing operation to the end of printing, and decreases after the transition to the sleep mode.

  On the other hand, in the evaluation machine A, as shown in the middle part of FIG. 8, the UFP concentration is substantially constant during the printing operation regardless of the passage of time. From the measurement result in the middle of FIG. 8, it can be understood that the evaluation machine A has UFP staying in the internal space of the exterior body 56. However, in the evaluator A, after the printing operation is completed, the internal space of the exterior body 56 is only an updraft, so that a large amount of UFP flows out of the exterior body 56. Therefore, as shown in the middle of FIG. 8, immediately after the end of printing, the UFP density increases rapidly and then gradually decreases.

  Further, in the evaluation machine B, as shown in the lower part of FIG. 8, the UFP concentration is substantially constant regardless of the passage of time, as in the evaluation machine A. Collected. Therefore, as shown in the lower part of FIG. 8, a large peak of UFP concentration does not occur immediately after the end of printing.

<Seventh column: Appendix>
In the above embodiment, the specifications of the fixing device 5 and the duty ratio of the PWM signal have been described with specific examples. However, not limited to the above, the specifications of the fixing device 5 and the duty ratio of the PWM signal are appropriately adjusted to appropriate values. In the above embodiment, the heat roller method is employed for the fixing device 5, but the present invention is not limited to this, and a heat belt method may be employed.

  In addition to the above, the first blower 57 serves to cool the sheet S discharged from the fixing device 5, and the second blower 59 serves to cool the image forming apparatus 1 in-machine other than the above. May be responsible.

  Moreover, in the said embodiment, the opening area of the 1st opening part 56a was demonstrated as variable. However, the present invention is not limited to this, and the opening area of the opening 56a is not necessarily variable as long as it is smaller than the opening 56b.

  When the opening area of the opening 56a is not variable, as shown in FIG. 9, a shutter member 56f that can be opened and closed under the control of the control circuit 7 may be provided on the upper part of the accommodating means 56d. . As shown in the upper part of FIG. 9, the shutter member 56f is closed during thermal fixing. As shown in the lower part of FIG. 9, the shutter member 56f is opened after the end of thermal fixing (during the post-processing), and the internal space of the housing 56d communicates with the peripheral region P2. This opening also forms part of the opening 56a. When the shutter member 56f is opened, the blower 57 sucks UFP inside the exterior body 56 through the opening 56a.

  Note that the opening 56a opened and closed by the shutter member 56f may be configured with one opening extending in the front-rear direction as shown in the upper part of FIG. 10 if there is no problem in strength. On the other hand, if there is a problem in strength, the opening 56a may be composed of a plurality of openings arranged in the front-rear direction as shown in the lower part of FIG.

<< Eighth column: Various modifications >>
As is well known, the conveyance speed of the sheet S may be changed depending on the printing conditions. Typically, when the basis weight is large, such as cardboard, the conveyance speed is relatively small as compared to the case where the basis weight is small, such as plain paper. The area of the opening 56a is large when the conveyance speed is smaller than a predetermined reference value (that is, when the basis weight of the sheet S is larger than the predetermined reference value) during thermal fixing, and is small otherwise. May be. Thereby, possibility that the sheet | seat S with a large basic weight will cause a sham in the opening part 56a can be reduced.

  Further, when printing is continuously performed on many sheets S, the amount of UFP generated increases. Therefore, the opening 56a may be made smaller as compared with a case where the number of sheets S to be heat-fixed is equal to or larger than a predetermined number. Thereby, it is possible to suppress the UFP from escaping to the outside of the exterior body 56 during the heat fixing.

  Also, the higher the heat fixing temperature, the greater the amount of UFP generated. Therefore, the opening 56a may be made smaller when the thermal fixing temperature is equal to or higher than a predetermined value as compared to when it is not. Thereby, it is possible to suppress the UFP from escaping to the outside of the exterior body 56 during the heat fixing.

  Also, the amount of UFP generated increases as the toner density on the sheet S increases, such as during full-color printing. Therefore, the opening 56a may be made smaller when the toner density is equal to or higher than a predetermined value as compared with the case where the toner density is not higher. Thereby, it is possible to suppress the UFP from escaping to the outside of the exterior body 56 during the heat fixing.

  Further, when the relative humidity is high, condensation tends to occur inside the fixing device 5. Therefore, the opening 56a may be enlarged as compared with a case where the relative humidity is not less than a predetermined value. Thereby, possibility that the water | moisture content adhering to the opening part 56a will adhere to the sheet | seat S can be reduced.

  Further, as described above, the amount of UFP generated during continuous printing increases. In other words, the longer the heat fixing execution time, the greater the amount of UFP generated. Therefore, after the heat fixing is completed, the intake time of the blowing unit 57 may be changed according to the execution time of the heat fixing. That is, the control circuit 7 may control the intake time to be longer as the heat fixing execution time is longer.

  The fixing device and the image forming apparatus according to the present invention can suppress a decrease in the thermal fixing temperature, and are suitable for a copying machine, a printer, a facsimile machine, and a multifunction machine having these functions.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 5 Fixing apparatus 51 1st rotary body 52 2nd rotary body 54 Heat source 56 Exterior body 56a 1st opening part 56b 2nd opening part 57 1st ventilation means 58 1st collection means 59 2nd ventilation means 510 1st Two collection means

Claims (14)

A plurality of rotating bodies that fix the toner to the sheet by thermal fixing;
An exterior body that covers each of the rotating bodies and has a first opening and a second opening above and below each of the rotating bodies, wherein ultrafine particles are applied to the plurality of rotating bodies during the heat fixing. An exterior body that stays in the facing space;
A first air blowing means for sucking air in a peripheral area of the first opening from above the first opening after the heat fixing;
First collecting means for separating and collecting ultrafine particles from the intake air of the first air blowing means;
During the heat fixing, the second air blowing means for sucking the peripheral area of the second opening from below the second opening and retaining ultrafine particles in the exterior body, and
During the heat fixing, the second air blowing means sucks air stronger than the first air blowing means, but after the heat fixing, the first air blowing means is stronger than the second air blowing means. Fixing device that performs intake .   The fixing device according to claim 1, wherein the amount of intake air of the first air blowing unit during the heat fixing is zero. The area of the first opening, the middle of at least the thermal fixing is smaller than the second opening, the fixing device according to claim 1 or 2. The area of the first opening, later completion of the thermal fixing is larger than during the heat fixing, fixing device according to any one of claims 1-3. The area of the first opening is small when the sheet conveyance speed is relatively large during the thermal fixing, and is large when the conveyance speed is relatively small. the fixing device according to any one of the three. Area of the first opening, while the thermal fixing, small when the basis weight of the sheet is relatively small, if the basis weight is large is increased, more of claims 1 to 3 A fixing device according to claim 1. Area of the first opening, when the number of sheets that were subject to the thermal fixing becomes more than a predetermined number, is smaller than in the less than predetermined number, fixing according to any one of claims 1 to 3 apparatus. The area of the first opening, if the temperature of the thermal fixing is equal to or more than the predetermined value is smaller than when less than the predetermined value, the fixing device according to any one of claims 1-3. The area of the first opening, the toner of the sheet is small when the relatively large fixing device according to any one of claims 1-3. The area of the first opening, if the relative humidity is above a predetermined value, is greater than when less than the predetermined value, the fixing device according to any one of claims 1-3. The intake time by the first blowing means is changed in accordance with the execution time of the heat fixing, fixing device according to any one of claims 1-10. The exterior body is
The sheet outlet and carry-in port provided above and below the plurality of rotating bodies, and
A guide member movable so as to adjust an opening area of the discharge port,
The outlet and the inlet port is in the first opening and the second opening, the fixing device according to any one of claims 1 to 1 1. The exterior body is
The sheet outlet and carry-in port provided above and below the plurality of rotating bodies, and
A shutter member provided in the vicinity of the discharge port, the shutter member being closed during the thermal fixing but being opened after the thermal fixing is completed,
The discharge port forms a part of the first opening, and the shutter member is opened to form another part of the first opening.
The entrance is in the second opening, the fixing device according to any one of claims 1 to 1 1. An image forming apparatus having a fixing device according to any one of claims 1 to 1 3.

Images