JP2007219430A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve image quality. <P>SOLUTION: The fixing device has: a fixing member which heats a developer on a recording medium; a press-contacting member 40 which forms a press-contact part with the fixing member; a separation member which separates the recording medium from the fixing member; and a cover member which forms a ventilation part between the fixing member and separation member. The separation member has an air hole 51a formed to make the ventilation part communicate with a conveyance path Rt for the recording medium. The cover member has an air intake port for taking air in. A communicating part 56a is formed which makes the air intake port and ventilation part communicate with each other. The air taken in through the air intake port is sent to the ventilation part through the communicating part 56a and sent to the conveyance path Rt through the air hole 51a, so that the separation member is heated with the air warmed by the fixing member. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

  2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile machine, a multifunction machine, for example, a printer has a fixing device as a fixing device, and the fixing device is heated and rotated with an upper roller, and A lower roller that is brought into pressure contact with the upper roller is provided, and the toner image on the paper is fixed to the paper by passing through a pressure contact portion between the upper roller and the lower roller.

  By the way, the paper on which the toner image is fixed is easily wound around the upper roller due to the adhesive action of the toner, which causes a paper jam.

Therefore, a separating member is arranged to separate and guide the sheet from the upper roller (see, for example, Patent Document 1).
JP 2005-37567 A

  However, in the conventional fixing device, when the paper passes through the pressure contact portion, water contained in the paper evaporates and water vapor is released to the paper conveyance path. At this time, immediately after the printer power is turned on, the surface temperature of the separation member, that is, the surface temperature is the same as the outside air temperature, so that the released water vapor is cooled by the separation member and is applied to the surface of the separation member. Condensation may occur. When condensation occurs, the paper gets wet and the image quality deteriorates.

  It is an object of the present invention to provide a fixing device and an image forming apparatus that can solve the problems of the conventional fixing device and improve the image quality.

  Therefore, in the fixing device of the present invention, a fixing member that is heated by a heating source and heats the developer on the recording medium, and a pressure contact member that is disposed in pressure contact with the fixing member and forms a pressure contact portion together with the fixing member. A separation member disposed opposite to the fixing member on the downstream side of the pressure contact portion in the conveyance direction of the recording medium, and separating the recording medium from the fixing member; and covering the fixing member and the separation member. And a cover member forming a ventilation portion between the separation member and the separation member.

  A vent hole is formed in the separation member to connect the vent portion and the recording medium conveyance path.

  Further, the covering member includes an air intake port for taking in air upstream from the pressure contact portion in the recording medium conveyance direction.

  And the communication part which connects this air intake port and a ventilation part is formed.

  According to the present invention, in the fixing device, a fixing member that is heated by a heating source and heats the developer on the recording medium, and a pressure contact member that is disposed in pressure contact with the fixing member and forms a pressure contact portion together with the fixing member. A separation member disposed opposite to the fixing member on the downstream side of the pressure contact portion in the conveyance direction of the recording medium, and separating the recording medium from the fixing member; and covering the fixing member and the separation member. And a cover member forming a ventilation portion between the separation member and the separation member.

  A vent hole is formed in the separation member to connect the vent portion and the recording medium conveyance path.

  Further, the covering member includes an air intake port for taking in air upstream from the pressure contact portion in the recording medium conveyance direction.

  And the communication part which connects this air intake port and a ventilation part is formed.

  In this case, a ventilation hole is formed by communicating the ventilation portion and the recording medium conveyance path, and air taken in from the air intake port is sent to the ventilation portion via the communication portion, and is conveyed via the ventilation hole. Since it is sent to the road, the separation member can be heated by the air heated by the fixing member. Therefore, no condensation occurs and the recording medium does not get wet, so that the image quality can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this case, a printer as an image forming apparatus will be described.

  FIG. 2 is a schematic view of the printer according to the first embodiment of the present invention.

  In the figure, reference numeral 11 denotes a paper feed cassette as a medium storage unit for storing paper P as a recording medium, and 12 is driven by a drive unit (not shown) to transfer the paper P stored in the paper feed cassette 11 to the transport path Rt. Supply, that is, a paper feed roller (hopping roller) as a medium supply member for feeding paper, pr1 and pr2 are pinch rollers as first transport rollers, and rr1 and rr2 are resists as second transport rollers. The paper P fed by the paper feed roller 12 passes between the pinch roller pr1 and the registration roller rr1, and further passes between the pinch roller pr2 and the registration roller rr2, The skew is corrected and sent to the image forming units 13Y, 13M, 13C, and 13Bk for each color of yellow, magenta, cyan, and black.The skew correction is performed by transporting the sheet with the registration roller rr2 stopped and abutting the front end against the registration roller rr2.

  Each of the image forming units 13Y, 13M, 13C, and 13Bk includes a photosensitive drum 20 as an image carrier that is rotated through a gear by driving a driving unit (not shown). Further, an endless transport belt 24 as a transport member is disposed along each image forming unit 13Y, 13M, 13C, 13Bk and in contact with each photosensitive drum 20, and the transport belt 24 is driven. It is stretched between the roller 101 and the driven roller 102 and is driven by rotating the driving roller 101. The paper P is transported by the transport belt 24 and passes between the image forming units 13Y, 13M, 13C, and 13Bk and the transfer rollers 22Y, 22M, 22C, and 22Bk as transfer members. The transfer belt 24, the transfer rollers 22Y, 22M, 22C, and 22Bk, the drive roller 101, and the driven roller 102 constitute a transfer unit. The transfer rollers 22Y, 22M, 22C and 22Bk are formed of a semiconductive rubber material or the like.

  Further, LED heads 21Y, 21M, 21C, and 21Bk as exposure apparatuses are disposed adjacent to the image forming units 13Y, 13M, 13C, and 13Bk.

  Each of the image forming units 13Y, 13M, 13C, and 13Bk includes an image forming unit main body 23, and a toner cartridge 19 as a developer accommodating portion that is detachably disposed with respect to the image forming unit main body 23. The image forming unit main body 23 includes the photosensitive drum 20, a charging roller 25 as a charging device, a developing roller 26 as a developing device, a cleaning blade 28 as a cleaning device, and the like. The toner cartridge 19 stores toner of each color as a developer.

  Therefore, after the surface of each photoconductor drum 20 is uniformly and uniformly charged by the charging roller 25, the surface is exposed to each LED head 21Y, 21M, 21C, 21Bk, and the surface of each photoconductor drum 20 is obtained. An electrostatic latent image is formed. Subsequently, the developing roller 26 develops each electrostatic latent image to form a toner image as a developer image of each color, and the transfer rollers 22Y, 22M, 22C, and 22Bk sequentially superimpose the toner images on the paper P. Transfer to form a color toner image. The toner remaining on the photosensitive drum 20 after the transfer is performed is removed by the cleaning blade 28.

  Subsequently, the paper P is sent to a fixing device 15 as a fixing device, and a color toner image is heated by a fixing roller 31 as a first roller and a fixing member, and pressed. A pressure is applied by the member 40 and the toner is fixed on the paper P to form a color image. The paper P discharged from the fixing device 15 is transported by the transport roller pair 16 and then discharged to the stacker 18 by the discharge roller pair 17. The stacker 18 also serves as an upper cover of the printer. Further, the transport roller pair 16 and the discharge roller pair 17 are rotated by driving a driving unit (not shown).

  Each of the image forming units 13Y, 13M, 13C, and 13Bk is detachably disposed with respect to the apparatus body 10 of the printer. For this purpose, an image forming unit upper surface cover 34 is disposed on the upper part of the apparatus body 10. The The LED heads 21Y, 21M, 21C, and 21Bk are held by the image forming unit upper surface cover 34.

  36 denotes an image in the conveyance direction of the paper P so that the influence of excess heat generated by the fixing device 15 does not reach the image forming units 13Y, 13M, 13C, and 13Bk. It is a fan as a blower device disposed downstream of the forming unit 13Bk and above the upstream of the fixing device 15.

  1 is a cross-sectional view of a fixing device according to the first embodiment of the present invention, FIG. 3 is a perspective view of the fixing device according to the first embodiment of the present invention, and FIG. 4 is a first embodiment of the present invention. FIG. 5 is a perspective view of the separator according to the first embodiment of the present invention, FIG. 6 is a perspective view of the main part of the separator according to the first embodiment of the present invention, and FIG. FIG. 8 is a cross-sectional view of another fixing device according to the first embodiment of the present invention.

  In the figure, 13Bk is an image forming unit, 15 is a fixing device, 20 is a photosensitive drum, 20Bk is an LED head, 22Bk is a transfer roller, 28 is a cleaning blade, 24 is a conveying belt, 101 is a driving roller, 103 is a belt frame, 31 is a fixing roller, and 32 is a pressure roller. The fixing roller 31 includes a halogen lamp 31a as a heating source therein, and is heated by the halogen lamp 31a to heat and melt the toner on the paper P. . The belt frame 103 holds the conveying belt 24, the transfer rollers 22Y, 22M, 22C, and 22Bk, the driving roller 101, and the driven roller 102.

  Cs is a casing of the fixing device 15, and the casing Cs covers an upper front cover 57 as a first covering member that covers the fixing roller 31 and a pressure contact member 40 that presses the sheet P against the fixing roller 31. 2 and a rear cover 53 as a third cover member that covers the separator 51 as a separation member. The fixing roller 31, the pressure contact member 40, and the like are accommodated in the housing Cs. The casing Cs has air as a fixing portion inlet for introducing the paper P conveyed from the image forming unit 13Bk into the pressure contact portion between the fixing roller 31 and the pressure contact member 40. An opening 56 serving as an air intake for taking in, and an opening 91 serving as an outlet for fixing the paper P to be discharged from the press contact portion and as an air exhaust for discharging air are formed. The pressure contact member 40 includes a pressure roller 32, a fixing belt 41 surrounding the pressure roller 32, and an outer peripheral surface having an arcuate shape, and a first belt guide member for guiding a front side portion of the fixing belt 41. A belt front guide 42 as a second belt guide member disposed adjacent to the belt front guide 42 and having an arcuate outer peripheral surface for guiding the rear portion of the fixing belt 41. A rear guide 43, a pressure pad 44 disposed inside the fixing belt 41, a pad holder 45 for holding the pressure pad 44, and a pressure spring 46 as an urging member are provided. The fixing belt 41 is stretched between a belt front guide 42, a belt rear guide 43 and a pressure roller 32.

  The pressure pad 44 is regulated by a pad holder 45 attached to the belt front guide 42 so as to move in a direction perpendicular to the transport direction of the paper P, and is pressed by a pressure spring 46 disposed on the pad holder 45. The paper P is urged in a direction perpendicular to the conveyance direction of the paper P, that is, upward.

  Further, on the downstream side of the fixing roller 31 and the pressure contact member 40 in the casing Cs, the separator 51 is above the transport path Rt, and the lower guide 54 as a medium guide member is below the transport path Rt. It is extended along the conveyance direction of P. The separator 51 is integrated with the holder 50 and attached to the housing Cs, and is disposed with one end close to the surface of the fixing roller 31 and the other end facing the opening 91. The lower guide 54 is disposed with one end being close to the surface of the fixing belt 41 and the other end facing the opening 91.

  By the way, when each color toner image is superimposed on the paper P to form a color toner image, and the color toner image is fixed by the fixing device 15, the paper P is curled, and the fixing roller is caused by the adhesive action of the toner. It becomes easy to wind around 31 and jam easily occurs. Therefore, as described above, since the separator 51 is disposed in the vicinity of the fixing roller 31, the paper P is separated from the fixing roller 31 by the separator 51 and guided toward the conveying roller pair 16.

  The separator 51 is formed with a plurality of vent holes 51a that allow the upper space Sp and the transport path Rt to communicate with each other over the length direction.

  The holder 50 includes an upper pressing portion 50c and a lower receiving portion 50d, and the separator 51 is sandwiched between the upper pressing portion 50c and the lower receiving portion 50d. At both ends of the holder 50, brackets 50a and 50b and a fixing member 50e raised from the lower receiving portion 50d are formed, holes 50f are formed in the brackets 50a and 50b, and holes 50g are formed in the fixing member 50e. . The shaft 52 is inserted into the holes 50f and 50g, and is laid between the brackets 50a and 50b and the fixing member 50e. The shaft 52 is attached in parallel to the fixing roller 31 and is fixed by fixing portions (not shown) disposed at both ends of the casing Cs of the fixing device 15. As a result, the separator 51 and the fixing roller 31 are arranged in parallel to each other.

  Further, in order to detect the surface temperature of the separator 51 in the central portion in the longitudinal direction of the separator 51, that is, in the vicinity of the vent hole 51a, a temperature sensor 55 as a temperature detection unit is disposed. The sensor output is sent to the control unit 60.

  The control unit 60 receives the sensor output sent from the temperature sensor 55, acquires the temperature detected by the temperature sensor 55, and sends a signal to the fan control unit 61 to control the fan 36.

  As shown in FIG. 1, the fan 36 sends air toward the transport path Rt of the paper P, and the air sent from the fan 36 in the direction of the arrow is directly below the transport path Rt and along the transport path Rt. The belt belt 103 is held on the surface of the arranged belt frame 103 and is deflected against the conveying belt 24 that travels. At this time, since the image forming unit 13Bk is disposed on the upstream side in the conveyance direction of the paper P, the air is deflected toward the fixing device 15 and is fixed to the fixing device 15 through the opening 56. Enter inside.

  Incidentally, at the lower end of the upper front cover 57 facing the opening 56 and the upper end of the lower front cover 58 facing the opening 56, introduction portions 57a and 58a for introducing air into the fixing device 15 are provided. It is formed so as to protrude toward the inside of the housing Cs. A gap that communicates between the opening 56 and the upper space Sp is formed between the introduction portion 57a and the surface of the fixing roller 31 as a communication portion 56a. Almost no gap is formed between the surface of the fixing roller 31. Accordingly, the air introduced through the opening 56 is sent into the upper space Sp constituting the ventilation portion between the upper front cover 57 and the fixing roller 31 via the communication portion 56a. The opening 56 has a channel cross-sectional area larger than that of the communication portion 56a.

  In the present embodiment, the fan 36 is arranged outside the fixing device 15, but as shown in FIG. 8, the fan 36 is placed in the upper space Sp in the fixing device 15. It can be arranged as. In that case, the air sucked by the fan 36 flows in the direction of the arrow, and an air flow is generated toward the vent hole 51a.

  Next, the operation of the fixing device 15 having the above configuration will be described.

  FIG. 9 is a relationship diagram between the operation time of the fixing device and the surface temperature of the separator in the first embodiment of the present invention. In the figure, the horizontal axis represents the operating time, and the vertical axis represents the separator surface temperature.

  In the figure, L1 indicates the surface temperature of the separator 51 when the vent hole 51a is formed, and L2 indicates the surface temperature of the separator 51 when the vent hole 51a is not formed.

  By the way, when the paper P passes through the pressure contact portion in the fixing device 15, the water contained in the paper P evaporates and water vapor is released to the transport path Rt. At this time, immediately after the printer is turned on and the surface temperature of the separator 51 is the same as the outside air temperature, if the released water vapor is cooled by the separator 51, dew condensation occurs on the surface of the separator 51. May occur.

  Therefore, when the printer is turned on, the air blowing control processing means (not shown) of the control unit 60 performs the air blowing control processing, starts the operation of the fan 36, and sends air toward the opening 56. While the air having entered the fixing device 15 from the opening 56 flows through the upper space Sp, the fixing roller is heated to a temperature close to 180 ° C. by the halogen lamp 31a for warm-up as a printing preparation operation. 31 is heated.

  Since the rear end portion of the fixing device 15 is covered by the rear cover 53, the air flowing through the upper space Sp is discharged to the transport path Rt through the vent hole 51a formed in the separator 51. In the meantime, the air heats the vicinity of the separator 51 and the conveyance path Rt. The air blowing control processing unit controls the fan 36 based on the temperature detected by the temperature sensor 55, and stops the fan 36 when the surface temperature of the separator 51 reaches 60 [° C.].

  In this case, as shown in FIG. 9, since the upper limit temperature at which condensation is likely to occur, that is, the condensation occurrence limit temperature is 50 ° C., the separator before the paper P reaches the fixing device 15 is used. 51 and the transport path Rt are sufficiently heated, and condensation does not occur. Therefore, the paper P does not get wet and the image quality can be improved.

  In addition, even when the surface temperature of the separator 51 does not reach 60 [° C.], for example, the surface temperature is lower than 50 [° C.] and condensation occurs on the separator 51, the air sent from the upper space Sp is Since the air flows from the upper side to the lower side through the vent hole 51a and is blown to the transport path Rt, the paper P is pushed down by the air and is flattened. Therefore, the paper P does not touch the separator 51 where condensation occurs, so the paper P does not get wet and the image quality can be improved.

  As described above, in the present embodiment, the air vent 51a is formed in the separator 51 of the fixing device 15 and the fan 36 is controlled to operate so that the air heated in the vicinity of the separator 51 and the transport path Rt is obtained. The feed, separator 51 and transport path Rt can be heated. Therefore, no condensation occurs, so that the paper P does not get wet and the image quality can be improved.

  By the way, when printing is performed using a thick sheet as the sheet P, it is necessary to increase the temperature of the fixing roller 31 in order to sufficiently heat the toner, whereas printing is performed using a thin sheet. When performing, it is necessary to lower the temperature of the fixing roller 31 so that the toner is not heated excessively. Therefore, for example, in order to print on a thin sheet immediately after printing on a thick sheet, it is necessary to cool the fixing roller 31 efficiently.

  Next, a second embodiment of the present invention provided with a device for cooling the fixing roller 31 will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 10 is a perspective view showing a first state of the fixing device according to the second embodiment of the present invention, FIG. 11 is a sectional view of the fixing device according to the second embodiment of the present invention, and FIG. FIG. 13 is a control block diagram of a fixing device according to the second embodiment of the present invention, and FIG. 14 is a control block diagram of the solenoid according to the second embodiment of the present invention. FIG. 15 is a sectional view showing a driving state of a solenoid according to the second embodiment of the present invention, and FIG. 16 is a second state of a fixing device according to the second embodiment of the present invention. FIG. 17 is a view showing a sub-cover in the second embodiment of the present invention. FIG. 17A is a front view of the sub cover, and FIG. 17B is a front view showing another example of the sub cover.

  In the present embodiment, an exhaust hole 71 is formed adjacent to the upper space Sp in the vicinity of the upper end of the rear cover 53, that is, upstream of the vent hole 51a in the air flow direction, and opens and closes the exhaust hole 71. For this purpose, a sub-cover 72 as an opening / closing member is disposed so as to be swingable. Further, in order to detect the surface temperature of the separator 51 in the vicinity of the vent hole 51a (FIG. 6), a temperature sensor 55 as a temperature detection unit is disposed, and the temperature sensor 55 outputs a sensor and outputs a temperature. The sensor output of the sensor 55 is sent to the control unit 60. The control unit 60 receives the sensor output sent from the temperature sensor 55, acquires the temperature detected by the temperature sensor 55, sends a signal to the fan control unit 61 to control the fan 36, and also controls the solenoid control unit. A signal is sent to 80 to control the solenoid 74.

  The air flow switching processing means of the control unit 60 performs air flow switching processing and closes the sub cover 72 when heating the separator 51. Accordingly, the air flows toward the separator 51. In addition, when the fixing roller 31 is cooled, the air flow switching processing means not only allows air to flow in the direction of the separator 51 but also opens the exhaust hole 71 to act as a heat radiating hole so that the air is enclosed. Released outside the body Cs. The sub cover 72 is urged by a torsion spring 73 in a direction to close the exhaust hole 71.

  For this purpose, in the upper space Sp in the housing Cs, a solenoid 74 is disposed as an air flow switching drive unit for opening and closing the sub cover 72 and as an opening and closing member. The solenoid 74 includes a coil 75, a plunger 76, a bobbin 77, and a frame 78 surrounding the coil 75 and the bobbin 77, and a bracket 72a of the sub cover 72 is engaged with a groove 76a formed in the vicinity of the tip of the plunger 76. Stopped. Therefore, normally, the solenoid 74 is placed in a non-driven state, and no current is supplied to the sub cover 72. As a result, as shown in FIG. 14, the plunger 76 is moved forward (moved rightward in the figure) by the urging force of the torsion spring 73, the sub cover 72 is rotated, and as shown in FIG. The exhaust hole 71 is closed.

  When a predetermined current is supplied to the coil 75 by the air flow switching processing means, an electromagnetic force is generated. Then, the solenoid 74 is driven by the generated electromagnetic force, and the plunger 76 is moved backward (moved leftward in the drawing) as shown in FIG. 15, and accordingly, the sub cover 72 is moved in the reverse direction. The exhaust hole 71 is opened as shown in FIG.

  The sub-cover 72 has a shielding portion 72a. The shielding portion 72a is formed between the exhaust holes 71 (FIG. 10) of the fixing device 15 so as to shield the exhaust holes 71. A non-shielding portion 72b is formed therebetween. The exhaust hole 71 can be closed by the shielding part 72a. On the other hand, when the exhaust hole 71 is opened, air can flow from the upper space Sp toward the exhaust hole 71 via the non-shielding part 72b. As shown in FIG. 17B, a sub cover 72 in which the non-shielding part 72b is not formed can be provided.

By the way, in the printer, printing may be performed using various types of paper P, and the control temperature of the fixing roller 31 varies depending on the type, thickness, and the like of the paper P. For example, when a standard paper having a thickness of 80 [g / m ² ] is used as the paper P, the temperature of the fixing roller 31 is set to 180 ° C., and a thin paper having a thickness of 64 [g / m ² ]. Is used, the temperature of the fixing roller 31 is set to 170 [° C.].

  Here, when printing is performed using thin paper immediately after using standard paper, the temperature of the fixing roller 31 must be lowered by about 10 [° C.]. In the first embodiment, the rear surface of the fixing device 15 is covered with the rear cover 53, and the exhaust is performed through the vent hole 51 a provided in the separator 51.

  Therefore, when the printer is turned on, the air blowing braking means operates the fan 36 and supplies air into the fixing device 15. At this time, the air flow switching processing means places the solenoid 74 in a non-driven state, rotates the sub-cover 72, and closes the exhaust hole 71. Thereafter, when the surface temperature of the separator 51 detected by the temperature sensor 55 reaches 60 [° C.], the air blowing braking processing means stops the fan 36.

  Thereafter, when the surface temperature of the separator 51 reaches 70 [° C.], even if the exhaust hole 71 is opened, the vicinity of the separator 51 and the transport path Rt does not reach a temperature at which dew condensation occurs. The means places the solenoid 74 in a driving state, rotates the sub cover 72, and opens the exhaust hole 71. Note that a fixing exhaust fan can be provided in order to exhaust the air in the upper space Sp from the exhaust hole 71 as necessary. Further, in order to detect the temperature of the fixing roller 31, a temperature sensor (not shown) is provided, and the sensor output of the temperature sensor is sent to the control unit 60. The control unit 60 can acquire the temperature detected by the temperature sensor and send a signal to the solenoid control unit 80 to control the solenoid 74 and open the exhaust hole 71. In this case, the temperature of the fixing roller 31 after the standard paper is used is 180 [° C.], and when the thin paper is used immediately thereafter, the temperature of the fixing roller 31 needs to be 170 [° C.]. At this time, after the standard paper is used, the temperature sensor controls the solenoid 74 and opens the exhaust hole 71 until the temperature of the fixing roller 31 reaches 170 [° C.], so that the fixing roller 31 is cooled quickly. can do.

  When the printer power is cut off or the power save mode is entered, the air flow switching processing means places the solenoid 74 in a non-driven state and closes the exhaust hole 71.

  As described above, in the present embodiment, when the air heated by the fixing roller 31 is sent to the transport path Rt through the vent hole 51a by closing the exhaust hole 71, the separator 51 and the transport path Rt. The vicinity can be sufficiently heated. Therefore, no condensation occurs, so that the paper P does not get wet and the image quality can be improved.

  Further, in the situation where the vicinity of the separator 51 and the transport path Rt is sufficiently warmed and no condensation occurs, the fixing roller 31 is opened by opening the exhaust hole 71 and actively exhausting the air in the housing Cs. Can be cooled and the warm-up time can be shortened. As a result, the time required for printing can be shortened.

  In each of the above embodiments, the fixing device including the fixing roller 31 and the fixing belt 41 is described. However, the present invention is applied to, for example, a fixing device including a heating roller and a pressure roller. Can do.

  In each of the embodiments, the solenoid 74 is used as an air flow switching drive unit to open and close the sub cover 72. For example, the tension is small at a low temperature, and at a high temperature. A shape memory alloy or the like that increases the tension can be used as the air flow switching drive unit. Further, an eccentric roller can be used for performing the opening / closing operation.

  In each of the above embodiments, a printer has been described. However, the present invention can be applied to an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile machine, and a multifunction machine.

  In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

1 is a cross-sectional view of a fixing device according to a first embodiment of the present invention. 1 is a schematic diagram of a printer according to a first embodiment of the present invention. FIG. 2 is a perspective view of a fixing device according to the first embodiment of the present invention. 1 is a schematic diagram of a fixing device according to a first embodiment of the present invention. It is a perspective view of the separator in the 1st Embodiment of this invention. It is a principal part perspective view of the separator in the 1st Embodiment of this invention. FIG. 3 is a control block diagram of the fixing device in the first embodiment of the present invention. It is sectional drawing of the other fixing device in the 1st Embodiment of this invention. It is a relationship diagram between the operation time of the fixing device and the surface temperature of the separator in the first embodiment of the present invention. It is a perspective view which shows the 1st state of the fixing device in the 2nd Embodiment of this invention. It is sectional drawing of the fixing device in the 2nd Embodiment of this invention. It is a perspective view of the solenoid of the fixing device in the second embodiment of the present invention. FIG. 6 is a control block diagram of a fixing device according to a second embodiment of the present invention. It is sectional drawing which shows the non-driving state of the solenoid in the 2nd Embodiment of this invention. It is sectional drawing which shows the drive state of the solenoid in the 2nd Embodiment of this invention. It is a perspective view which shows the 2nd state of the fixing device in the 2nd Embodiment of this invention. It is a figure which shows the sub cover in the 2nd Embodiment of this invention.

Explanation of symbols

15 Fixing device 31 Fixing roller 31a Halogen lamp 40 Pressure contact member 51 Separator 51a Vent hole 53 Rear cover 56 Opening portion 56a Communication portion 57 Upper front cover 58 Lower front cover P Paper Rt Transport path

Claims (9)

(A) a fixing member that is heated by a heating source and heats the developer on the recording medium;
(B) a pressure contact member disposed in pressure contact with the fixing member and forming a pressure contact portion together with the fixing member;
(C) a separation member disposed opposite to the fixing member on the downstream side of the pressure contact portion in the recording medium conveyance direction and separating the recording medium from the fixing member;
(D) a cover member that covers the fixing member and the separation member and forms a ventilation portion between the fixing member and the separation member;
(E) A vent hole is formed in the separation member to communicate the vent portion with a recording medium conveyance path;
(F) The covering member includes an air intake port that takes in air upstream from the pressure contact portion in the conveyance direction of the recording medium,
(G) A fixing device in which a communication portion is formed to communicate the air intake port and the ventilation portion.   The fixing device according to claim 1, wherein the communication portion is formed between a fixing member and a cover member.   The fixing device according to claim 1, wherein the air intake port is larger than the communication portion.   The fixing device according to claim 1, wherein an airflow generation unit that generates an air flow toward the ventilation hole is disposed in the ventilation unit. (A) The covering member includes an exhaust hole formed on the upstream side of the vent hole in the air flow direction,
(B) The fixing device according to any one of claims 1 to 4, wherein the exhaust hole is opened and closed by an opening and closing member. (A) a drive unit for operating the opening and closing member;
The fixing device according to claim 5, further comprising: (b) an air flow switching processing unit that drives the driving unit to open and close the exhaust hole.   An image forming apparatus comprising the fixing device according to claim 1.   An image forming apparatus comprising the fixing device according to claim 1, and having a blower that sends air to the air intake port. The image forming apparatus according to claim 8, further comprising a blowing control processing unit that controls the blowing device.

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