Image forming device

Abstract

To efficiently cool a heating device even after the occurrence of abnormality.SOLUTION: In a situation in which opening of a cover is not detected by an opening and closing detection unit after heat generation of a heat source is stopped due to abnormality, an air blowing device blows air to a heating device. When the absence of a recording medium at a nip part is detected by a recording medium detection unit, two rotating bodies rotate. When a temperature detected by a temperature detection unit becomes equal to or less than a preset threshold T before the opening of the cover is detected by the opening and closing detection unit, an image forming apparatus reduces the amount of air blown from the air blowing device.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus. [Background technology]

[0002] 2. Description of the Related Art As an example of a heating device installed in an image forming apparatus such as a copier or a printer, a fixing device is known that heats paper while sandwiching the paper between a pair of rotating bodies such as an endless belt or rollers, thereby fixing an image on the paper.

[0003] In the fixing device, since the heat of the non-paper passing area where the paper does not pass tends not to be taken away by the paper, when multiple sheets of paper are passed continuously, the heat of the rotating body in the non-paper passing area gradually accumulates, and the temperature rise becomes significant. In order to address this problem, in conventional image forming devices, in order to suppress the temperature rise of the fixing device, a blower such as a fan is used to blow air to the non-paper passing area of ​​the rotating body (for example, see Patent Document 1: JP 2012-118487 A). Summary of the Invention [Problem to be solved by the invention]

[0004] However, in conventional image forming devices, when the image forming device stops operating, the air blowing operation of the air blowing device also stops, so that after the image forming device stops operating, air cannot be blown to the fixing device, and the fixing device may not be sufficiently cooled. [Means for solving the problem]

[0005] In order to solve the above problem, the present invention provides an image forming apparatus comprising two rotating bodies that come into contact with each other to form a nip portion through which a recording medium passes, a heating device having a heat source that heats at least one of the two rotating bodies, a blower that blows air to the heating device, a temperature detection unit that detects the temperature of at least one of the two rotating bodies, a recording medium detection unit that detects whether the recording medium is present in the nip portion, a cover that is openable and closable on the main body of the image forming apparatus, and an opening / closing detection unit that detects the opening and closing of the cover, wherein after heat generation by the heating source stops due to an abnormality, in a state in which the opening of the cover is not detected by the opening / closing detection unit, the blower blows air to the heating device, and when the recording medium detection unit detects that the recording medium is not present in the nip portion, the two rotating bodies rotate, and before the opening of the cover is detected by the opening / closing detection unit, the air volume of the blower is reduced. Effect of the Invention

[0006] According to the present invention, the heating device can be effectively cooled even after an abnormality occurs. [Brief description of the drawings]

[0007] [Figure 1] 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention; [Diagram 2] FIG. 2 is a diagram showing a paper passing area in the fixing device. [Diagram 3] FIG. 2 is a plan view showing the configuration of the blower device. [Figure 4] FIG. 2 is a side view showing the configuration of the blower device. [Diagram 5] FIG. 2 is a block diagram showing a control system. [Figure 6] 2A and 2B are diagrams illustrating a cover provided in the image forming apparatus and an open / close detector that detects whether the cover is open or closed. [Figure 7] FIG. 3 is a timing chart showing the operations of the blower fan and the rotating body according to the first embodiment of the present invention. [Figure 8]FIG. 3 is a flowchart illustrating a control method for a blower fan and a rotating body according to the first embodiment of the present invention. [Figure 9] FIG. 11 is a timing chart showing the operations of the blower fan and the rotating body according to the second embodiment of the present invention. [Figure 10] FIG. 11 is a flowchart illustrating a control method for a blower fan and a rotating body according to a second embodiment of the present invention. [Figure 11] FIG. 11 is a timing chart showing the operations of the blower fan and the rotating body according to the third embodiment of the present invention. [Figure 12] FIG. 13 is a diagram showing an example in which a blower fan and a temperature sensor are disposed on the fixing member side. [Figure 13] FIG. 13 is a diagram showing an example in which a blower fan and a temperature sensor are disposed on both the fixing member side and the pressure member side. [Figure 14] 11A and 11B are diagrams illustrating examples of other fixing devices to which the present invention can be applied. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The present invention will be described below with reference to the accompanying drawings. In each drawing for explaining the present invention, components such as members and components having the same function or shape are given the same reference numerals as far as they can be distinguished, and the description thereof will be omitted after the first description.

[0009] FIG. 1 is a schematic diagram of an image forming apparatus according to an embodiment of the present invention. In this specification, the term "image forming apparatus" includes a printer, a copier, a facsimile, a printing machine, or a multifunction machine that combines two or more of these. In addition, the term "image formation" used in the following description means not only forming an image having meaning such as a character or a figure, but also forming an image having no meaning such as a pattern. First, the overall configuration and operation of the image forming apparatus according to this embodiment will be described with reference to FIG. 1.

[0010] As shown in FIG. 1, the image forming apparatus 1 according to this embodiment includes an image forming unit 2 that forms an image on a sheet-like recording medium such as paper, a fixing unit 3 that fixes the image on the recording medium, a recording medium supply unit 4 that supplies the recording medium to the image forming unit 2, and a recording medium discharge unit 5 that discharges the recording medium outside the apparatus.

[0011] The image forming unit 2 is provided with a photoconductor 6 as an image carrier that carries an image on its surface, a charging member 7 that charges the surface of the photoconductor 6, an exposure member 8 that forms an electrostatic latent image on the surface of the photoconductor 6, a developer supply member 9 that supplies toner as a developer to the surface of the photoconductor 6 to form a toner image, a cleaning member 10 that cleans the surface of the photoconductor 6, and a transfer member 11 that transfers the image to a recording medium.

[0012] The fixing section 3 is provided with a fixing device 20 that fixes the transferred image onto the recording medium. The fixing device 20 includes a fixing member 21 that is heated by a heat source such as a halogen heater, and a pressure member 22 that is pressed relatively against the fixing member 21. The fixing member 21 and the pressure member 22 are rotating bodies such as rollers or endless belts, and are in contact with each other to form a nip portion.

[0013] The recording medium supply unit 4 is provided with a paper feed cassette 12 that stores paper P as a recording medium, and a paper feed roller 13 that feeds paper P from the paper feed cassette 12. In the following description, the "recording medium" will be described as "paper", but the "recording medium" is not limited to paper (paper). The "recording medium" includes not only paper (paper), but also overhead projector sheets or fabrics, metal sheets, plastic films, or prepreg sheets in which carbon fibers are pre-impregnated with resin. In addition to plain paper, "paper" also includes cardboard, postcards, envelopes, thin paper, coated paper (coated paper, art paper, etc.), tracing paper, and the like.

[0014] The recording medium discharge section 5 is provided with a pair of discharge rollers 14 for discharging the paper P outside the image forming apparatus, and a paper discharge tray 15 on which the paper P discharged by the paper discharge rollers 14 is placed.

[0015] Next, the printing operation of the image forming apparatus 1 according to this embodiment will be described with reference to FIG.

[0016] When the printing operation is started, the photoconductor 6 starts to rotate in the image forming unit 2, and the surface of the photoconductor 6 is charged to a uniform high potential by the charging member 7. Next, the exposure member 8 exposes the surface of the photoconductor 6 based on the image information of the document read by the document reading device or the print information instructed to be printed from the terminal. This reduces the potential of the exposed portion, and an electrostatic latent image is formed on the surface of the photoconductor 6. Then, toner is supplied from the developer supply member 9 to this electrostatic latent image, and a toner image is formed on the photoconductor 6.

[0017] The toner image formed on the photoreceptor 6 reaches a transfer nip where the photoreceptor 6 and the transfer member 11 come into contact with each other as the photoreceptor 6 rotates, and is transferred to the paper P at the transfer nip. This paper P is supplied from the recording medium supply unit 4. In the recording medium supply unit 4, the paper P stored in the paper feed cassette 12 is sent out one by one as the paper feed roller 13 rotates. The sent out paper P comes into contact with the timing roller pair 16 before reaching the transfer nip, and the conveyance is temporarily stopped. Thereafter, the paper P is conveyed to the transfer nip by the timing roller pair 16 in synchronization with the toner image on the photoreceptor 6. Then, at the transfer nip, the toner image on the photoreceptor 6 is transferred to the paper P. After the toner image is transferred, the toner remaining on the photoreceptor 6 is removed by the cleaning member 10.

[0018] The paper P onto which the toner image has been transferred is transported to the fixing device 20 and enters between the fixing member 21 and the pressure member 22 (the nip portion). Then, the paper P is transported while being sandwiched between the fixing member 21 and the pressure member 22, so that the toner image on the paper P is heated and pressurized, and is fixed to the paper P. Thereafter, the paper P is discharged onto the paper discharge tray 15 by the paper discharge rollers 14, and a series of printing operations is completed.

[0019] FIG. 2 is a diagram showing a paper passage area in the fixing device according to the present embodiment.

[0020] 2, the fixing device 20 according to this embodiment is configured to allow at least two types of paper P1, P2 of widths W1, W2 to pass through. In this example, the case where two types of paper P1, P2 of different widths are passed through is shown, but the types of paper that can be passed through may be three or more. In addition, the width of the paper here refers to the width of the paper in a direction perpendicular or intersecting the conveying direction Y in which the paper is conveyed, and in the same direction as the longitudinal direction or rotation axis direction of the fixing member 21 and the pressure member 22.

[0021] 2, in the fixing device 20 according to this embodiment, the heat source 23 is disposed across the entire width of the maximum paper passing area (maximum recording medium passing area) A through which the paper P1 of the maximum width W1 passes, so that the fixing process can be performed well regardless of the size of the paper. The heat source 23 in this embodiment is a halogen heater disposed inside the fixing member 21, but may be another radiant heater such as a carbon heater or a ceramic heater. An IH (electromagnetic induction heating) type heat source may also be used as the heat source. The heat source may be disposed inside the pressure member 22 as well as inside the fixing member 21.

[0022] In this manner, in this embodiment, since the heating source 23 is disposed over the entire width of the maximum paper passing area A, various types of paper can be uniformly heated overall, and good fixing processing can be performed. However, when a paper P2 having a minimum width smaller than the maximum width of the paper P1 is passed through, the temperature of the fixing member 21 and the pressure member 22 is likely to rise in the non-paper passing area B (the area outside the paper passing area C in the width direction) where the paper P2 does not pass through. That is, in the non-paper passing area B, heat associated with paper passing is not easily consumed and tends to accumulate, so when multiple sheets of paper having a width smaller than the maximum width are passed continuously, the temperature rise in the non-paper passing area B becomes significant. As a result, there is a risk that the temperature of the fixing member 21 or the pressure member 22 will exceed the heat resistance temperature. Therefore, in this embodiment, in order to suppress the temperature rise of the fixing member 21 and the pressure member 22 in the non-paper passing area B, an air blower (cooling device) as described below is provided.

[0023] 3 and 4 show the configuration of the air blower (cooling device) according to this embodiment.

[0024] As shown in FIG. 3, in this embodiment, the air blowing devices 30 are disposed on both ends of the pressure member 22 in the longitudinal direction. Specifically, each air blowing device 30 includes an air blowing fan 31 as an airflow generating member that generates an airflow, and a duct 32 as a flow path forming member that guides the airflow from the air blowing fan 31 toward the outer circumferential surface of the pressure member 22. The air blowing port 32a of each duct 32 is disposed so as to face or be close to the outer circumferential surface of the pressure member 22 in the non-paper passing region B. The non-paper passing region B shown in FIG. 3 is a non-paper passing region when a paper sheet P2 having a width W2 smaller than the maximum width shown in FIG. 2 is passed through, and is an example of a non-paper passing region. Therefore, when there are multiple non-paper passing regions with different widths depending on the type of paper being passed through, the size and position of the air blowing port 32a of the duct 32 may be appropriately set according to the position and width of the selected non-paper passing region.

[0025] In this embodiment, the air outlet 32a of each duct 32 is disposed to face or be close to the outer peripheral surface of the pressurizing member 22 in the non-paper passing region B. When an airflow is generated by the rotation of each blower fan 31, the airflow is blown from the air outlet 32a of each duct 32 to the outer peripheral surface of the pressurizing member 22 in the non-paper passing region B. This cools the non-paper passing region B of the pressurizing member 22. In addition, by cooling the non-paper passing region B of the pressurizing member 22, the non-paper passing region B of the fixing member 21 that contacts the pressurizing member 22 is also indirectly cooled. As a result, the temperature rise in the non-paper passing region B of each of the fixing member 21 and the pressurizing member 22 is suppressed. In particular, as in the example shown in FIG. 3, when the air outlet 32a of each duct 32 is formed to expand toward the downstream side in the air blowing direction, the airflow can be blown over a wide range, so that effective cooling is possible. 4, in this embodiment, each air blower 30 is disposed so as to blow air downstream of the nip portion N in the paper transport direction Y, but each air blower 30 may be disposed so as to blow air upstream of the nip portion N in the paper transport direction Y. Also, instead of the air blower fan, a suction fan may be used as the airflow generating member.

[0026] Incidentally, when an abnormality such as a paper jam or a breakdown occurs while an image forming apparatus is in operation, the operation of the image forming apparatus is generally stopped temporarily, and various operations such as an image forming operation in an image forming section, a paper conveying operation in a recording medium supply section or the like, a fixing operation in a fixing section, and a paper ejection operation in a recording medium ejection section are stopped temporarily even if they are in the middle of being performed.

[0027] Usually, a user or an operator such as a serviceman will then perform recovery work. In that case, the operator inserts his or her hand into the image forming apparatus to remove jammed paper or replace parts, but the fixing apparatus and its surroundings may be hot immediately after the image forming apparatus stops operating and the fixing member and pressure member of the fixing apparatus stop rotating. Therefore, it is preferable to cool the fixing apparatus before the operator starts the recovery work. However, in conventional image forming apparatuses, when the image forming apparatus stops operating, the cooling device also stops operating, making it impossible to effectively cool the fixing apparatus.

[0028] Therefore, in the image forming apparatus according to the present invention, the following control system is adopted so that the fixing device can be effectively cooled even after the image forming apparatus has stopped operating due to an abnormality.

[0029] FIG. 5 is a block diagram showing a control system for the blower device and the fixing device according to the present embodiment.

[0030] 5, the image forming apparatus according to this embodiment includes a control unit 40 that controls the drive source 33 that rotates the blower fan 31 and the drive source 26 that rotates the fixing member 21 and the pressure member 22. The control unit 40 is a microcomputer having, for example, a RAM (Random Access Memory) and a ROM (Read Only Memory), and in addition to controlling the drive source 33 of the blower fan 31 and the drive source 26 of the fixing member 21 and the pressure member 22, it also controls various operations such as an image forming operation in the image forming unit, a paper feeding operation in the recording medium supply unit, a fixing operation in the fixing unit, and a paper discharge operation in the recording medium discharge unit.

[0031] The control unit 40 controls the start and stop of the blowing operation (rotation) of the blower fan 31, and also adjusts the air volume (rotation speed) by controlling the rotation speed. Here, the "air volume" refers to the amount of air moved by the blower fan 31 per unit time, and the air volume Q (m 3 / h) is the function of the passing wind speed V (m / s) and the passing area A (m 2 ) The air volume can be measured using a hot wire anemometer or a vane anemometer. The control unit 40 controls the rotation speed of the fixing member 21 and the pressure member 22 in addition to starting and stopping the rotation of the fixing member 21 and the pressure member 22.

[0032] As shown in FIG. 5, the control unit 40 controls the driving sources 33 and 26 based on the temperature detected by the temperature detection unit 70 , the detection signal from the recording medium detection unit 60 , and the detection signal from the open / close detection unit 50 .

[0033] The temperature detection unit 70 has temperature sensors 24, 25 arranged in the paper passing area C and the non-paper passing area B shown in Fig. 3, respectively. One temperature sensor 24 is arranged at least on the outside in the width direction of the minimum paper passing area (minimum recording medium passing area) and on the inside in the width direction of the maximum paper passing area (maximum recording medium passing area), and the other temperature sensor 25 is arranged at least on the inside in the width direction of the minimum paper passing area. Here, the "inside in the width direction" of the paper passing area means a space that exists in a direction perpendicular to the width direction (arrow X direction in Fig. 3) of the paper passing area. In contrast, the "outside in the width direction" of the paper passing area means a space outside the space that exists in a direction perpendicular to the width direction of the paper passing area.

[0034] Moreover, each of the temperature sensors 24, 25 is disposed facing but not in contact with the outer circumferential surface of the pressing member 22 (see FIG. 4). In this case, each of the temperature sensors 24, 25 detects the ambient temperature in the vicinity of the pressing member 22. Note that each of the temperature sensors 24, 25 may be a contact-type temperature sensor that contacts the outer circumferential surface of the pressing member 22 and detects the surface temperature of the pressing member 22.

[0035] The recording medium detection unit 60 has a fixing entrance sensor 61 and a fixing exit sensor 62 shown in FIG. 4. The fixing entrance sensor 61 detects the paper P in the vicinity of the upstream side of the nip N in the paper transport direction Y, and the fixing exit sensor 62 detects the paper P in the vicinity of the downstream side of the nip N in the paper transport direction Y. The control unit 40 determines whether the paper P is present in the nip N based on a detection signal from at least one of these sensors 61 and 62. That is, the control unit 40 can determine whether the paper P has passed through the nip N (whether the paper P is present in the nip N) from the timing at which the paper P is detected by at least one of the fixing entrance sensor 61 and the fixing exit sensor 62, and the length and transport speed of the paper P. The fixing entrance sensor 61 and the fixing exit sensor 62 may be contact sensors that detect by contacting the paper, or non-contact sensors that detect without contacting the paper.

[0036] The open / close detection unit 50 is a sensor that detects the open / close of the cover 18 provided in the image forming apparatus main body 100 shown in FIG. 6. The open / close detection unit 50 is, for example, a transmission type photosensor that transmits light and outputs a signal when the light blocking member is retracted when the cover 18 is opened, or a microswitch that detects the operation of an actuator equipped with a spring and a hinge lever. The open / close detection unit 50 is not limited to a unit that directly detects the open state of the cover 18, but may be a unit that indirectly detects the open state of the cover 18 by detecting the closed state of the cover 18. That is, the open / close detection unit 50 only needs to be able to detect at least one of the open state and the closed state of the cover 18.

[0037] FIG. 7 is a timing chart showing the operation of the blower fan and the operation of each rotating body (fixing member and pressure member) included in the fixing device.

[0038] 7, (a) shows the temperature in the non-paper passing area of ​​the fixing device, (b) shows the temperature in the paper passing area of ​​the fixing device, (c) shows the operating state (output amount) of the blower fan, (d) shows the rotational operation of the fixing member and the pressure member when no paper is present in the nip area, and (e) shows the rotational operation of the fixing member and the pressure member when paper is present in the nip area. The temperature of the fixing device detected in the paper passing area and non-paper passing area may be the temperature of pressure member 22 or the temperature of fixing member 21.

[0039] 7, timing (1) on the horizontal axis indicates the timing when the image forming apparatus stops operating due to an abnormality while performing normal image forming operation, and the power supply to the heating source of the fixing device and the rotation of each rotating body (fixing member, pressure member) are stopped. Timing (2) indicates the timing when the opening / closing detection unit 50 detects the opening of the cover 18 of the image forming apparatus body when an operator opens the cover 18 for recovery work.

[0040] Hereinafter, a method for controlling the blower device 30 and the fixing device 20 according to the present embodiment will be described with reference to the timing chart shown in FIG. 7 and the flow chart shown in FIG.

[0041] In the image forming apparatus according to the present embodiment, if an abnormality such as a paper jam or a malfunction occurs during operation, the operation of the image forming apparatus is temporarily stopped and various operations of the image forming apparatus are stopped, similar to a general image forming apparatus. Specifically, the various operations stopped due to the abnormality include the image forming operation in the image forming unit, the paper feeding operation in the recording medium supply unit, the fixing operation in the fixing unit, and the paper ejection operation in the recording medium ejection unit. Furthermore, the fixing operation stopped due to the abnormality includes the supply of power to the heating source (heat generation from the heating source) as well as the rotation of the fixing member and the heating member.

[0042] In a conventional image forming apparatus, when the operation of the image forming apparatus stops due to an abnormality, various operations including the operation (rotation) of the blower fan are stopped. In contrast, in the image forming apparatus according to the present embodiment, unlike the conventional apparatus, even if various operations of the image forming apparatus stop due to an abnormality (STEP 1 in FIG. 8), the controller 40 controls the blower fan 31 to continue the blowing operation (rotation) (STEP 2 in FIG. 8).

[0043] Furthermore, in the image forming apparatus according to this embodiment, after the image forming apparatus stops operating due to an abnormality, the recording medium detection unit 60 (fixing entrance sensor 61 and fixing exit sensor 62) detects whether or not a sheet is present in the nip portion (STEP 3 in FIG. 8). As a result, if the recording medium detection unit 60 detects that no sheet is present in the nip portion, the control unit 40 controls the fixing member 21 and the pressure member 22 to start rotating (STEP 4 in FIG. 8). In this case, the blowing of air by the blower fan 31 continues while the fixing member 21 and the pressure member 22 rotate.

[0044] On the other hand, when the recording medium detection unit 60 detects the presence of paper in the nip portion, the fixing member 21 and the pressure member 22 do not start to rotate. Therefore, in this case, the fixing member 21 and the pressure member 22 are not rotated, and only cooling is performed by blowing air from the blower fan 31.

[0045] Thereafter, when the temperature of the pressure member 22 in the non-paper passing area detected by the temperature detection unit 70 falls below a preset threshold value T (see FIG. 7), the control unit 40 slows down the rotation speed of the blower fan 31 to gradually reduce the air volume (STEPs 5 to 7 in FIG. 8).

[0046] Thereafter, the blowing operation of the blower fan 31 and the rotation operation of the fixing member 21 and the pressure member 22 when there is no paper in the nip portion continue until the opening / closing detection unit 50 detects that the cover 18 is open (STEP 8 in FIG. 8). On the other hand, when the opening / closing detection unit 50 detects that the cover 18 is open, the blowing operation (rotation) of the blower fan 31 and the rotation operation of the fixing member 21 and the pressure member 22 are stopped by the control unit 40 (STEP 9 in FIG. 8), and the control of the blower device and the fixing device after the occurrence of the abnormality is terminated.

[0047] As described above, in the embodiment of the present invention, even after the image forming apparatus stops driving due to an abnormality (after the heat source 23 of the fixing device 20 stops generating heat due to an abnormality), the blower fan 31 continues blowing (rotating), so that airflow is blown to the non-paper passing area B of the pressure member 22. As a result, the fixing member 21 and the pressure member 22 can be effectively cooled even after the image forming apparatus stops driving (after the heat source 23 of the fixing device stops generating heat), and the safety of the operator when performing the recovery work thereafter is improved. Furthermore, when no paper is present in the nip portion, the fixing member 21 and the pressure member 22 can be more effectively cooled by rotating the fixing member 21 and the pressure member 22 in addition to blowing air by the blower fan 31. On the other hand, when paper is present in the nip portion, the fixing member 21 and the pressure member 22 are not rotated, so that paper jams caused by paper being transported from the fixing device when the transport operation of the image forming apparatus is stopped are prevented.

[0048] The rotation speed of the fixing member 21 and the pressure member 22 after the abnormal stop (after the heating source 23 stops generating heat due to an abnormality) is preferably set slower than the rotation speed of the fixing member 21 and the pressure member 22 when the paper passes through the nip part under normal circumstances. In addition, if multiple rotation speeds of the fixing member 21 and the pressure member 22 under normal circumstances are set, the rotation speed after the abnormal stop is preferably set slower than the slowest rotation speed among them. During normal printing operation, the fixing member 21 and the pressure member 22 rotate at a relatively high speed, so if the fixing member 21 and the pressure member 22 are rotated at a similar high speed even after the abnormal stop, the rotation distance will be unnecessary and the life of the fixing device will be shortened. For this reason, by slowing down the rotation speed of the fixing member 21 and the pressure member 22 after the abnormal stop, unnecessary rotation can be suppressed and the life of the fixing device can be prevented from being shortened.

[0049] Furthermore, in this embodiment, when the temperature detected by the temperature detection unit 70 falls below a preset threshold T, the air volume is reduced, thereby improving energy conservation. In other words, when the detected temperature falls below the preset threshold T, the risk of the worker coming into contact with a high-temperature part is reduced, and there is no need to blow air at a high volume, so that the power required to drive (rotate) the blower fan 31 can be reduced by reducing the air volume. Thus, the configuration according to this embodiment not only improves safety, but also improves energy conservation.

[0050] 7, when the detected temperature becomes equal to or lower than the threshold value T, the air volume of the blower fan 31 is controlled to be continuously reduced at a constant rate, but the reduction in the air volume may be continuous, stepwise, or intermittent. The reduction in the air volume does not necessarily have to be at a constant rate, and the air volume may be reduced variably based on the detected temperature, etc. Such control of the air volume is possible not only by changing the rotation speed of the blower fan 31, but also by changing the opening area of ​​the duct 32 by a shutter, etc.

[0051] Next, an embodiment of the present invention that is different from the above-mentioned embodiment (first embodiment) will be described. In the following description, the differences from the above-mentioned embodiment will be mainly described, and the other parts will be omitted as they are basically the same in configuration.

[0052] 9 and 10 are a timing chart and a flow chart showing a control method according to the second embodiment of the present invention.

[0053] As shown in FIG. 9, in the second embodiment of the present invention, two thresholds T1 and T2 are set in advance as thresholds of the detected temperature. One of the thresholds, T1, is the same as the threshold set in the above embodiment, and is a first threshold (first reference temperature) that is a reference for the timing to reduce the air volume of the blower fan 31. The other threshold, T2, is a threshold set to a temperature lower than the first threshold, and is a second threshold (second reference temperature) that is a reference for the timing to stop the blowing operation (rotation) of the blower fan 31 and the rotation of the fixing member 21 and the pressure member 22. For example, the second threshold T2 is set to a temperature that ensures safety even if an operator touches the fixing member 21 or the pressure member 22.

[0054] In this embodiment, the control (STEP 1 to STEP 7 in FIG. 10) until the air volume of blower fan 31 is adjusted (air volume reduced) after the image forming apparatus stops driving due to an abnormality is basically the same as the control in the first embodiment. That is, after the image forming apparatus stops driving due to an abnormality (after the heat source of the fixing device stops generating heat), the blowing by blower fan 31 continues, and further, if no paper is present in the nip portion, fixing member 21 and pressure member 22 are rotated. Thereafter, if the temperature detected by temperature detection unit 70 becomes equal to or lower than first threshold value T1, the air volume of blower fan 31 is reduced.

[0055] Thereafter, when the temperature detected by the temperature detection unit 70 becomes equal to or lower than the second threshold value T2, the blowing operation (rotation) of the blower fan 31 is stopped (STEPs 8 to 10 in FIG. 10). Also, when the fixing member 21 and the pressure member 22 are rotating, their rotation operations are also stopped. This ends a series of controls after the occurrence of an abnormality in the second embodiment. Note that in this embodiment, when the open / close detection unit 50 detects that the cover 18 is open before the temperature detected by the temperature detection unit 70 becomes equal to or lower than the second threshold value T2, the blowing operation (rotation) of the blower fan 31 and the rotation operations of the fixing member 21 and the pressure member 22 are stopped at that timing.

[0056] In this way, in the second embodiment of the present invention, when the temperature detected by the temperature detection unit 70 becomes equal to or lower than the first threshold value T1, the air volume is reduced, and further, when the detected temperature becomes equal to or lower than the second threshold value T2, the airflow is stopped, thereby further improving energy saving. That is, even before the cover 18 is opened, when the temperature of the fixing member 21 or the pressure member 22 drops to a level (second threshold value T2) at which airflow is not required, the airflow is stopped, thereby reducing the power required to drive (rotate) the air blower fan 31. In addition, by stopping the rotation of the fixing member 21 and the pressure member 22, the power consumption supplied to them can also be reduced.

[0057] In this embodiment, as in the first embodiment described above, the detected temperature compared with the first threshold value T1 and the second threshold value T2 is the temperature in the non-paper passing area of ​​the pressure member 22, but the detected temperature compared with the threshold value may be the temperature in the paper passing area of ​​the pressure member 22, or the temperature in the paper passing area or non-paper passing area of ​​the fixing member 21.

[0058] In the first and second embodiments, the blowing fan 31 continues to blow air from before the image forming apparatus is stopped due to an abnormality until after the image forming apparatus is stopped (see Figs. 7 and 9), but the blowing fan 31 may start to blow air when or after the image forming apparatus is stopped as in a third embodiment of the present invention shown in Fig. 11. Also, as in the example shown in Fig. 11, the rotation of the fixing member 21 and the pressure member 22 when no paper is present in the nip portion may continue without being stopped once an abnormality occurs.

[0059] 12, each air blower 30 and each temperature sensor 24, 25 may be disposed on the fixing member 21 side, not on the pressure member 22 side. In this case, after the image forming apparatus stops driving due to an abnormality, each air blower 30 blows air to the outer circumferential surface of the fixing member 21.

[0060] Furthermore, as in the example shown in FIG. 13, the air blowing devices 30 and the temperature sensors 24, 25 may be disposed on both the fixing member 21 side and the pressure member 22 side.

[0061] 3 and 4. For example, the fixing device may be configured as shown in FIG. 14, which includes an endless fixing belt 81 as a fixing rotator (first rotator), a pressure roller 82 as a pressure rotator (second rotator), a plate-shaped heater 83 as a heat source, a heater holder 84 as a heat source holding member that holds the heater 83, and a stay 85 as a support member that supports the heater holder 84. In this case, the pressure roller 82 is pressed against the heater 83 via the fixing belt 81, so that a nip N is formed between the fixing belt 81 and the pressure roller 82. In an image forming apparatus including such a fixing device 80, the fixing belt and the pressure roller can be effectively cooled by applying the present invention.

[0062] Furthermore, the present invention is not limited to cooling a fixing device, but can also be applied to cooling a heating device other than a fixing device. For example, the present invention can be applied to cooling a drying device (heating device) that heats paper to dry liquid such as ink discharged onto the paper in an inkjet image forming apparatus. [Explanation of symbols]

[0063] 1. Image forming device 18 Cover 20 Fixing device (heating device) 21 Fixing member (first rotating body) 22 Pressurizing member (second rotating body) 23 Heating source 30 Blower 31 Blower fan (airflow generating component) 32 Duct (flow path forming member) 40 Control section 50 Open / close detection unit 60 Recording medium detection unit 70 Temperature detection unit 100 Image forming apparatus body N Nip section P Paper (recording medium) [Prior art documents] [Patent documents]

[0064] [Patent Document 1] JP 2012-118487 A

Claims

1. a heating device having two rotating bodies that come into contact with each other to form a nip portion through which a recording medium passes, and a heat source that heats at least one of the two rotating bodies; A blower that blows air to the heating device; A temperature detection unit that detects a temperature of at least one of the two rotating bodies; a recording medium detection unit that detects whether the recording medium is present in the nip portion; a cover provided on a main body of the image forming apparatus in an openable and closable manner; An opening / closing detection unit that detects opening / closing of the cover, After the heat source stops generating heat due to an abnormality, in a state in which the open / close detection unit does not detect the opening of the cover, the air blower blows air to the heating unit, and in a state in which the recording medium detection unit detects that the recording medium is not present in the nip portion, the two rotating bodies rotate, An image forming apparatus characterized in that, if the detected temperature of the temperature detection unit falls below a predetermined threshold before the opening / closing detection unit detects the opening of the cover, the air volume of the blower device is reduced.

2. The image forming apparatus of claim 1, wherein the air blowing device and the rotation of the two rotating bodies continue until the open / close detection unit detects that the cover is open, and when the open / close detection unit detects that the cover is open, the air blowing device stops blowing, and when the two rotating bodies are rotating, the rotation of each of the rotating bodies stops.

3. When the temperature detected by the temperature detection unit becomes equal to or lower than a first threshold value set in advance before the opening / closing detection unit detects the opening of the cover, the air volume of the air blower is reduced; 2. The image forming apparatus according to claim 1, wherein if the detected temperature of the temperature detection unit falls below a second threshold set to a temperature lower than the first threshold before the opening / closing detection unit detects the opening of the cover, the blower stops blowing air, and if the two rotating bodies are rotating, the rotation of each of the rotating bodies is stopped.

4. 4. An image forming apparatus according to claim 1, wherein the rotational speed of the two rotating bodies that rotate after the heat source stops generating heat due to an abnormality is slower than the rotational speed of the two rotating bodies when a recording medium passes through the nip portion under normal circumstances.

5. The image forming apparatus according to claim 1 , wherein the air blowing device blows air to at least one of the two rotating bodies on an outer side in the width direction of a minimum recording medium passing area.

6. 6. The image forming apparatus according to claim 1, wherein the temperature detected by the temperature detection unit is the temperature of at least one of the two rotating bodies detected on an outer side in the width direction of a minimum recording medium passing area.

7. The heating device includes: A first rotating body; a second rotating body that contacts an outer circumferential surface of the first rotating body to form a nip portion through which a recording medium passes; 7. The image forming apparatus according to claim 1, wherein the image forming apparatus is a fixing device including a heat source for heating the first rotating body.

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