Image forming apparatus

Abstract

To provide a fixing device that uses an air blast mechanism as measures against an increase in the temperature of a non-paper feeding part occurring when a small-sized sheet is fed, and prevents the occurrence of downtime.SOLUTION: A fixing device comprises: a heating unit that applies heat to a recording material; a pressure rotating body that is in contact with the heating unit to form a nip part, the pressure rotating body sandwiching and conveying the recording material with the heating unit to fix a toner image to the recording material; first air blast means that sends air to one end of the heating unit in a width direction orthogonal to a conveyance direction of the recording material; second air blast means that sends air to the other end of the heating unit in the width direction; and a control section that controls the first air blast means and the second air blast means independent of each other.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to an image forming apparatus for forming an image on a recording material. [Background technology]

[0002] 2. Description of the Related Art An electrophotographic image forming apparatus includes a fixing device that applies heat and pressure to a recording material on which an unfixed toner image has been formed, thereby fixing the toner image to the recording material.

[0003] In recent years, in order to improve energy saving performance and shorten standby time, a fixing device using a fixing film with low heat capacity has been proposed. Fixing film type fixing devices use a heating unit having a fixing film and a pressure roller that contacts the fixing film. A recording material is conveyed to a nip portion formed between the fixing film and the pressure roller. Then, heat and pressure are applied to the recording material, so that a toner image is fixed to the recording material.

[0004] When the process of fixing the recording material is performed continuously, a temperature rise in the non-paper passing area may occur. The temperature rise in the non-paper passing area occurs when a recording material (small size paper, narrow width paper) having a width smaller than the maximum paper passing width of the image forming device (maximum size paper) is continuously passed in the width direction perpendicular to the conveying direction of the recording material. When the maximum size paper is passed and fixed, the surface of the fixing film and the pressure roller has a substantially uniform temperature distribution over the entire length of the fixing area. However, when small size paper is passed and fixed continuously, the temperature of the surface of the non-paper passing area of ​​the fixing film and the pressure roller rises excessively. This is because when small size paper is passed, a non-paper passing area where the recording material does not pass exists within the maximum paper passing width. In the non-paper passing area, heat is not taken away by the recording material, but is accumulated.

[0005] If a temperature rise occurs in the non-paper passing area, it can damage surrounding components, and if larger sized paper, including the maximum size paper, is passed in the next job, excessive heat can be applied. To prevent this, if a temperature rise occurs in the non-paper passing area, image formation is temporarily suspended, and downtime occurs until the temperature of the non-paper passing area drops. However, downtime is undesirable because it reduces the productivity of the image forming device.

[0006] Patent Document 1 discloses a blowing mechanism for blowing air to a non-paper passing area of ​​a fixing film to cool it. The blowing mechanism has a fan, and the fan is controlled according to a temperature detected by a temperature detection member provided in an area where air can be blown among the non-paper passing areas of the fixing film or the heating means (heater). [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2013-134421 A Summary of the Invention [Problem to be solved by the invention]

[0008] When small-sized paper is passed through, the temperature of the non-paper passing portions of the fixing film rises at both ends. The fixing device described in Patent Document 1 controls the air blowing mechanisms at both ends using the temperature detected by the thermistors at the ends of the heating units. The air blowing mechanisms at both ends are controlled in the same way.

[0009] Depending on the recording material being passed through, it may be conveyed biased toward one end or the other end in the width direction. This causes a difference in temperature between the non-paper passing portion on one end side and the non-paper passing portion on the other end side. Here, in a configuration in which the air blowing mechanisms provided at both ends of the heating unit are controlled in the same way, there is a risk that either the non-paper passing portion on one end side or the non-paper passing portion on the other end side may be cooled excessively or insufficiently. In cases in which either the non-paper passing portion on one end side or the non-paper passing portion on the other end side is cooled excessively or insufficiently, downtime occurs because the temperature of the heating unit needs to be adjusted to an appropriate temperature.

[0010] SUMMARY OF THE DISCLOSURE An object of the fixing device according to the present invention is to prevent downtime in a fixing device that uses a blower mechanism as a countermeasure against temperature rise in non-paper passing areas that occurs when small size paper is passed through the fixing device. [Means for solving the problem]

[0011] In consideration of the above problems, the fixing device of the present invention is characterized in that it includes a heating unit that applies heat to a recording material, a pressure rotating body that contacts the heating unit and forms a nip portion, the pressure rotating body fixes a toner image to the recording material by nipping and transporting the recording material together with the heating unit, a first air blowing means that blows air to one end of the heating unit in a width direction perpendicular to the transport direction of the recording material, a second air blowing means that blows air to the other end of the heating unit in the width direction, a first temperature detection means that detects a temperature of the one end of the heating unit, a second temperature detection means that detects a temperature of the other end of the heating unit, a control unit that controls the first air blowing means and the second air blowing means based on temperature detection by the first temperature detection means and the second temperature detection means, and is capable of assuming a state in which the first air blowing means and the second air blowing means are blowing air, a state in which the first air blowing means blows air and the second air blowing means is not blowing air, and a state in which the first air blowing means does not blow air and the second air blowing means is blowing air. Effect of the Invention

[0012] According to the fixing device of the present invention, in a configuration in which an air blowing mechanism is used as a countermeasure against a rise in temperature in non-paper passing areas that occurs when small size paper is passed through, it is possible to suppress the occurrence of downtime. [Brief description of the drawings]

[0013] [Figure 1] FIG. 13 is a diagram (longitudinal temperature distribution diagram) showing a problem when this embodiment is not implemented. [Diagram 2] FIG. 13 is a diagram (longitudinal temperature distribution diagram) showing a problem when this embodiment is not implemented. [Diagram 3] FIG. 2 is a diagram for explaining a mechanism by which surface wear is promoted. [Figure 4] 1 is a cross-sectional view of a printer which is an image forming apparatus according to an embodiment of the present invention. [Diagram 5] FIG. 2 is a schematic cross-sectional view of a fixing device according to the present embodiment. [Figure 6] FIG. 2 is a schematic front view of the fixing device according to the present embodiment. [Figure 7] FIG. 2 is a schematic cross-sectional view of a fixing film in the present embodiment. [Figure 8] 2 is a schematic cross-sectional view of a fixing device and a cooling mechanism according to the embodiment. [Figure 9] FIG. 2 is a diagram illustrating a drive configuration of a shutter in the present embodiment. [Figure 10] FIG. 4 is a diagram illustrating shutter driving in the first embodiment. [Figure 11] FIG. 4 is a diagram illustrating shutter driving in the first embodiment. [Figure 12] FIG. 2 is a control block diagram in the first embodiment. [Figure 13] FIG. 2 is a flow chart according to the first embodiment. [Figure 14] FIG. 2 is a flow chart according to the first embodiment. [Figure 15] FIG. 4 is a diagram showing the relationship between fan strength and a temperature detection means in the first embodiment. [Figure 16] 11 is a graph showing a temperature transition before and after carrying out this embodiment. [Figure 17] 11 is a graph showing temperature transitions after carrying out this embodiment. [Figure 18] FIG. 11 is a flow chart according to the second embodiment. [Figure 19] FIG. 2 is a perspective view of a blower mechanism in the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] <Example 1> <Image forming device> 4 is a cross-sectional view of the image forming apparatus 1 of this embodiment. The image forming apparatus 1 is an image forming apparatus in which a toner image formed on a photosensitive drum 11 is transferred to a recording material P in an image forming section 10, and then the image is fixed to the recording material P by a fixing device 40.

[0015] As shown in Fig. 4, the image forming apparatus 1 includes an image forming unit (image forming station) 10 that forms toner images of the colors Y (yellow), M (magenta), C (cyan), and Bk (black). The image forming unit 10 includes four photosensitive drums 11 (11Y, 11M, 11C, and 11Bk) corresponding to the colors Y, M, C, and Bk, respectively, from the left side of Fig. 4, and are driven to rotate in the direction of the arrow in the photosensitive drum 11 by a drive source.

[0016] Around each photosensitive drum 11, there are arranged a charger 12, an exposure device 13, a developing device 14, a primary transfer blade 17, and a cleaner 15. Below, a procedure for forming a Bk toner image will be described, but the procedure for forming toner images of other colors (Y, M, C) is similar.

[0017] First, a procedure for forming a toner image on a recording material P will be described. The surface of the photosensitive drum 11 is uniformly charged by the charger 12, and then exposed by the exposure device 13 according to image information, forming an electrostatic latent image on the photosensitive drum 11. Then, the developing device 14 develops toner onto the electrostatic latent image, forming a toner image on the photosensitive drum 11. At this time, similar processes are performed for the other colors (Y, M, C, etc.).

[0018] The toner image on each photosensitive drum 11 is primarily transferred to the intermediate transfer belt 31 by the primary transfer blade 17, and the toner remaining on the photosensitive drum 11 is removed by the cleaner 15. In this way, the photosensitive drum 11 becomes ready for the next image formation.

[0019] Meanwhile, the recording material P placed on the feeding cassette 20 or the multi-feed tray 25 is fed one by one by the feeding mechanism and sent to the registration roller pair 23. The registration roller pair 23 temporarily stops the recording material P, and corrects the skew if the recording material P is skewed with respect to the conveying direction. Next, the registration roller pair 23 synchronizes with the toner image on the intermediate transfer belt 31 and sends the recording material P between the intermediate transfer belt 31 and the secondary transfer roller 35. The secondary transfer roller 35 transfers the toner image on the intermediate transfer belt 31 to the recording material P.

[0020] The recording material P onto which the toner image has been transferred is conveyed to a fixing device 40, where the toner image is fixed onto the recording material P by heat and pressure treatment.

[0021] <Fixing device> Next, the fixing device 40 will be described. Fig. 5 shows a cross-sectional view of the fixing device 40, and Fig. 6 shows a front view of the fixing device 40. The heating unit 60, which heats the image on the recording material P, is configured to heat a flexible, thin fixing film 603 by a heater 600 that contacts the inner surface. As shown in Fig. 5, a nip portion N is formed in the fixing film 603 by pressing the heater 600 and the pressure roller 70, and the recording material P fed to the nip portion N is sandwiched and conveyed. At this time, the heat generated by the heater 600 is applied to the recording material P via the fixing film 603, and the toner image T on the recording material P is melted and fixed to the recording material P.

[0022] The heating unit 60 is a unit for applying heat and pressure to an image on the recording material P, and is provided parallel to the pressure roller.

[0023] The fixing film 603 is pressed toward the pressure roller 70 so that the nip portion N has a predetermined width. The heater 600 includes a substrate 610 and a resistance heating element 620 on the substrate 610, and is fixed to a recess in the lower surface of the heater holder 601. In this embodiment, the heating element 620 is provided on the back side of the substrate 610 (the side that does not come into contact with the fixing film 603), but the present invention is not limited to this and the heating element 620 may be provided on the front side (the side that comes into contact with the fixing film 603).

[0024] A semi-solid lubricant (hereinafter, grease) made of a solid component (compound) and a base oil component (oil) is applied to the surface of the substrate 610 in order to reduce the friction load between the fixing film 603 and the heater 600. The grease ensures the sliding properties between the heater 600 and the fixing film 603, and between the heater holder 601 and the fixing film 603. Examples of the grease compound include solid lubricants such as graphite and molybdenum disulfide, metal oxides such as zinc oxide and silica, and fluororesins such as polytetrafluoroethylene (PTFE). Examples of the grease oil include heat-resistant polymeric resin oils such as silicone oil and fluorosilicone oil. In this embodiment, grease using PTFE powder fine particles (particle size 3 μm) as the compound and fluorosilicone oil as the oil is used.

[0025] The fixing film 603 is a cylindrical film for applying heat and pressure to the toner image on the recording material at the nip portion N. FIG. 7 shows the layer structure of the fixing film 603. In this embodiment, an elastic layer 603b and a release layer 603c are provided on a substrate 603a, and an inner surface sliding layer 603d is provided on the inner surface of the substrate 603a. Specifically, a cylindrical member made of a nickel alloy with an outer diameter of 30 mm, a length of 340 mm, and a thickness of 30 μm is used as the substrate 603a. Furthermore, a silicone rubber layer with a thickness of 400 μm is formed as the elastic layer 603b on the substrate 603a, and a fluorine resin tube with a thickness of about 20 μm is further coated on the elastic layer 603b as the release layer 603c. Furthermore, a polyimide layer (PI layer) with a thickness of about 10 μm is used as the inner surface sliding layer 603d.

[0026] The heater holder 601 (hereinafter, holder 601) is a member that holds the heater 600 in a state pressed against the fixing film 603. The holder 601 also has a function of regulating the rotational trajectory of the fixing film 603. The heater holder 601 is made of a highly heat-resistant resin or the like, and in this embodiment, Zenite 7755 (product name) by DuPont is used.

[0027] The support stay 602 is a member that supports the heater 600 via the heater holder 601. The support stay 602 is desirably made of a material that is not easily bent even when a large load is applied, and in this embodiment, stainless steel (SUS304) is used.

[0028] As shown in FIG. 6, the support stay 602 is supported by flanges 411a and 411b at both ends in the longitudinal direction. The flanges 411a and 411b are collectively called flanges 411. The flanges 411 regulate the longitudinal movement and circumferential shape of the fixing film 603. Heat-resistant resin or the like is used for the flange 411, and polyphenylene sulfide (PPS) is used in this embodiment. A pressure spring 415 is provided in a compressed state between the flange 411 and the pressure arm 414. With the above configuration, the elastic force of the pressure spring 415 is transmitted to the heater 600 via the flange 411 and the support stay 602. Then, the fixing film 603 is pressed against the pressure roller 70 with a predetermined pressing force, and a nip portion N of a predetermined width is formed. In this embodiment, the pressure force is about 156.8 N at one end, and the total pressure force is about 313.6 N (32 kgf).

[0029] The connector 500 is a power supply member that is electrically connected to the heater 600 in order to apply a voltage to the heater 600, and is detachably attached to one end of the heater 600 in the longitudinal direction.

[0030] As shown in FIG. 5, the pressure roller 70 as a pressure rotating body is a member that forms a nip portion N by being pressed by the heating unit 60. The pressure roller 70 has a multi-layer structure in which an elastic layer 72 is provided on a metal core 71, and a release layer 73 is further provided on the elastic layer 72. The core 71 can be made of stainless steel (SUS), sulfur and sulfur composite free-cutting steel material (SUM), or aluminum. The elastic layer 72 can be made of silicone rubber, sponge rubber, or elastic foam rubber. The release layer 73 can be made of fluororesin materials such as tetrafluoroethylene-perfluoroalkylvinylether copolymer (PFA). The pressure roller 70 of this embodiment is made of a stainless steel core 71, a silicone rubber elastic layer 72, and a PFA tube release layer 73, and has an outer diameter of about 25 mm and a longitudinal length of the elastic layer of 330 mm.

[0031] As shown in Fig. 6, the core 71 of the pressure roller 70 is rotatably supported via the side plate 41 and bearings 42a and 42b, and a gear G is provided at one end of the core 71 to transmit the driving force of a motor M1 to the core 71. As shown in Fig. 5, the pressure roller 70 driven by the motor M1 is driven to rotate in the direction of the arrow, and transmits the driving force to the fixing film 603 at the nip portion N to rotate it. In this embodiment, the motor M1 is controlled by the control circuit portion 90 so that the surface speed of the pressure roller 70 is 200 mm / sec.

[0032] The thermistor (TH) 630, which is a temperature detection means shown in FIG. 5, is provided on the rear side of the heater 600 and is a temperature sensor that detects the temperature of the heater 600. The thermistor 630 is connected to the control circuit section 90 via an A / D converter and transmits an output corresponding to the detected temperature to the control circuit section 90. The control circuit section 90 is a circuit equipped with a CPU that performs calculations associated with various controls and a non-volatile medium such as a ROM. This ROM stores programs, and the CPU reads and executes these programs to execute various controls. The control circuit section 90 is electrically connected to a power source so as to control the power supply. In addition, the control circuit section 90 reflects the temperature information acquired from the thermistor 630 in the power supply power supply control, thereby controlling the power supplied to the heater 600. In this embodiment, a method is used in which the amount of heat generated by the heater 600 is adjusted by performing wave number control or phase control on the power supply output, and the heater 600 is maintained at a predetermined temperature when fixing the toner on the recording material. Three thermistors 630 are arranged in the fixing device 40 of this embodiment. In the width direction perpendicular to the conveying direction of the recording material, one is provided at the center of the fixing film 603 (TH1 (third temperature detection means)), and the remaining two are provided at each end of the fixing film 603 (TH2, 3). The thermistor used to control the temperature of the heater 600 is thermistor TH1. Since the center in the width direction is an area through which the recording material always passes, it is preferable to use a thermistor that detects the temperature at the center to control the heater 600. Furthermore, thermistor (TH) 630 detects the temperature within the maximum paper passing area of ​​the recording material in the width direction perpendicular to the conveying direction of the recording material.

[0033] <Blower mechanism> The blower mechanism 800 according to this embodiment will be described with reference to FIGS. 8 and 9. The blower mechanism 800 is provided to suppress the temperature rise of the non-paper passing portion of the fixing film 603, which occurs when small-sized recording materials are continuously fixed, by cooling (blowing air). The blower mechanism 800 has a fan 44 and a duct 45 that guides the air of the fan 44. As shown in FIG. 19, there may be a plurality of fans. The duct 45 has an air outlet 46 (a first air outlet 46L and a second air outlet 46R), and the air outlet 46 is provided at a position facing the end of the fixing film 603 that becomes the non-paper passing area when the small-sized recording material is fixed. The air of the fan 44 is guided to the end of the fixing film 603 through the air outlet 46. The blower mechanism 800 has a shutter 47 as an adjustment member that adjusts the opening width of the air outlet 46 according to the width of the recording material used, and a shutter drive unit (not shown) that drives the shutter 47.

[0034] 19, the blower mechanism 800 has a fan 44 at each end, a duct 45LR (first duct 45L and second duct 45R) for guiding the wind from the fan 44, an air outlet 46, and a shutter 47 (first shutter 47L and second shutter 47R). This allows air to be blown to one end and the other end of the heating unit 60. The fan 44, the duct 45, the air outlet 46, and the shutter 47 are arranged symmetrically on the left and right sides of the longitudinal direction of the fixing film 603 (first air blowing means and second air blowing means). In this embodiment, an axial fan is used as the fan 44, but a centrifugal fan such as a sirocco fan may also be used.

[0035] Here, the drive configuration of the shutter 47 will be described. The shutter drive device 48 has a support plate 49, rack teeth 50, a pinion gear 51, and a motor M3. The two left and right shutters 47 are supported so as to be slidable in the left and right direction along the plate surface of the support plate 49 extending in the left and right direction and forming the air outlet 46. The shutters 47 are connected by the rack teeth 50 and the pinion gear 51, and the pinion gear 51 is rotated forward and backward by forward and reverse driving of the motor (pulse motor) M3. As a result, the left and right shutters 47 are linked to each other to open and close in a symmetrical relationship with respect to the corresponding air outlet 46. As shown in FIG. 9, the shutter drive device 48 is configured by the support plate 49, rack teeth 50, pinion gear 51, and motor M3.

[0036] The left and right ventilation openings 46 are provided from a position slightly closer to the center than the non-paper passing portion b that occurs when the minimum-width recording material is passed through, to the maximum paper passing width W1. The left and right shutters 47 are arranged in a direction that closes the ventilation openings 46 by a predetermined amount from the center toward the ends in the longitudinal direction of the support plate 49.

[0037] When the width information of the recording material P is the maximum size recording material, the control circuit unit 90 controls the shutter drive device 48 to move to a fully closed position where the ventilation port 46 is closed by the shutter 47 as shown in Fig. 10. When the recording material is a small size recording material with an A4 portrait feed width, the control circuit unit 90 moves the shutter 47 to a position where the ventilation port 46 is opened to a portion corresponding to the non-paper passing portion as shown in Fig. 11. The position information of the shutter 47 is detected by a flag (not shown) arranged at a predetermined position of the shutter 47, detected by a sensor (not shown) arranged on the support plate 49. Specifically, the home position is determined at the shutter position where the ventilation port 46 is fully closed as shown in Fig. 10, and the opening amount is detected from the amount of rotation of M3.

[0038] <Control Unit> The image forming apparatus 1 includes a control circuit section 90. The control circuit section 90 will be described with reference to Fig. 12. However, in addition to those shown in the figure, various devices for operating the image forming apparatus 1 are connected to the control circuit section 90, but as this is not the main point of the invention, illustration and description of these devices will be omitted here.

[0039] FIG. 12 is a block diagram showing the configuration of a control system in the image forming apparatus. A control circuit section 90 as a control means performs various controls of the image forming apparatus 1, such as an image forming operation, and has, for example, a CPU and a memory. The memory is composed of a ROM (Read Only Memory) and a RAM (Random Access Memory). The memory stores various programs for controlling the image forming apparatus 1 and various data such as the maximum size width of the recording material P on which an image can be formed. The CPU can execute various programs stored in the memory, and executes the various programs to operate the image forming apparatus 1. In this embodiment, the CPU can execute the "image formation job processing (program)" and the "cooling control processing (program)" stored in the memory. The memory can also temporarily store the results of calculations associated with the execution of the various programs.

[0040] An image forming job is a series of operations from the start of image formation to the completion of image forming operations based on a print signal for forming an image on a recording material P. That is, it is a series of operations from the start of a preparatory operation (so-called pre-rotation) required for performing image formation, through the image forming process, to the completion of a preparatory operation (so-called post-rotation) required for completing image formation. Specifically, it refers to the period from the pre-rotation after receiving a print signal (preparatory operation before image formation) to the post-rotation (operation after image formation), and includes the image formation period and the paper interval.

[0041] The control circuit section 90 is further connected to the fixing drive motor M1, the shutter motor M4, the heater energizing circuit 92, the first temperature detection means (TH2) 630, and the second temperature detection means (TH3) 630 via an input / output interface. The first temperature detection means (TH2) 630 and the second temperature detection means (TH3) 630 detect the temperature of the heating unit 60. In this embodiment, the temperature of the back side of the heater 600 is detected, but the present invention is not limited to this and may be configured to detect the temperature of the fixing film 603. The first temperature detection means (TH2) 630 and the second temperature detection means (TH3) 630 are provided at symmetrical positions with respect to the center of the fixing film 603 in the width direction. When the first temperature detection means (TH2) 630 and the second temperature detection means (TH3) 630 are provided at symmetrical positions, it is preferable because the difference in temperature rise at both ends of the heating unit 60 can be accurately observed.

[0042] In addition, the fan motor M2 (one end) and the fan motor M3 (the other end), which are the features of this embodiment, are connected to each other. When an instruction to start an image forming job is given from an external host device or the like, the control circuit unit 90 executes the "image forming job process" stored in the memory. The control circuit unit 90 controls the image forming apparatus 1 based on the execution of the "image forming job process". Accordingly, the control circuit unit 90 drives the fixing drive motor M1 to rotate the pressure roller 70, thereby rotating the fixing film 603. Then, the control circuit unit 90 controls the temperature by the heater current circuit 92 so that the surface temperature of the fixing film 603 becomes a desired target temperature. Then, the control circuit unit 90 controls the fan motor M2 (one end) and the fan motor M3 (the other end) according to the outputs of the temperature detection means (TH2) 630 and the second temperature detection means (TH3) 630, and performs cooling by the fans. In this embodiment, cooling by the fans is performed independently at each of the one end and the other end.

[0043] Conventionally, cooling by fans was controlled in the same way at one end and the other end. Specifically, a thermistor, which is a temperature detection means for detecting the temperature at one end and the other end of the heating unit 60, is provided. When the temperature detected by the thermistor reaches a predetermined temperature, the fan provided at each end of the heating unit 60 is operated. This suppresses the temperature rise in the non-paper passing portion. However, there are cases where the recording material is conveyed out of alignment in the width direction of the fixing film 603, which is a direction perpendicular to the conveying direction of the recording material.

[0044] For example, in the image forming apparatus 1 in this embodiment in which the recording material is transported vertically from the bottom to the top from the feeding cassette 20 to the paper discharge tray, the apparatus may not have a function to correct misalignment of the recording material in the width direction. In such an apparatus, the recording material is transported to the fixing device 40 while being misaligned in the width direction. Furthermore, if the recording material is small-sized paper that is smaller in the width direction than the maximum size at which the image forming apparatus can form an image, a temperature rise occurs in the non-paper passing portion. The temperature rise in the non-paper passing portion that occurs between one end and the other end creates a temperature difference by the amount of the misalignment of the recording material in the width direction.

[0045] If the cooling fan is controlled identically at one end and the other end, the temperature difference caused by the shift of the recording material in the width direction cannot be filled, and one end or the other end may be cooled too much or insufficiently.

[0046] In this embodiment, in order to suppress this temperature difference, the cooling by the fans is controlled independently at one end and the other end.

[0047] <Cooling by fan> A specific procedure will be described with reference to the flow chart of FIG. 13. When a print signal is received, the heater 600 starts to be energized, the pressure roller 70 is rotated via the fixing drive motor M1, and the fixing film 603 is heated (S001). When the fixing film 603 or the heater 600 reaches the target temperature, paper feed is started (S002). The control circuit unit 90 judges whether the detection result of the first temperature detection means 630 (TH2) has reached the first temperature (S003: Yes). When the detection temperature of the first temperature detection means 630 (TH2) has reached the first temperature (S003: Yes), the control circuit unit 90 drives the fan motor M2 (one end portion) to start cooling the one end portion (S004). When the detection result of the first temperature detection means 630 (TH2) has not reached the first temperature (S003: No), it judges whether the job is completed (S007).

[0048] When cooling of the one end portion is performed, the control circuit unit 90 judges whether the detection result of the first temperature detection means 630 (TH2) is below the first temperature (S005). When the detection result of the first temperature detection means 630 (TH2) is below the first temperature (Yes in S005), the control circuit unit 90 stops driving the fan motor M2 (one end portion) and stops cooling of the one end portion (S006). When the detection result of the first temperature detection means 630 (TH2) is not below the first temperature (No in S005), the control circuit unit 90 continues driving the fan motor M2 (one end portion) and continues cooling of the one end portion (S004).

[0049] In S007, it is determined whether the job has been completed, and if it has been completed (Yes in S007), the operation of the image forming apparatus is stopped. If it has not been completed (No in S007), paper passing is continued (S002).

[0050] FIG. 15 shows the details of the cooling operation of S004. The airflow rate of the fan motor M2 (one end) is controlled according to the detection result (detected temperature) of the first temperature detection means 630 (TH2). The airflow rate is the amount of air blown per unit time, and in this embodiment, since a fan is used as the blowing means, it refers to the airflow rate by the fan. The airflow rate is determined by the rotation speed of the fan, so it may be the rotation speed. When the detection result of the first temperature detection means 630 (TH2) reaches the first temperature, cooling of the one end starts, but the strength of the cooling fan at that time is set to 30% (the maximum output value of the cooling fan is set to 100%). As the detection result of the first temperature detection means 630 (TH2) increases, the strength of the cooling fan is increased from 30%. When the detection result of the first temperature detection means 630 (TH2) reaches the first temperature + 10°C, the output value of the cooling fan is set to the maximum value of 100%.

[0051] A more detailed explanation will be given with reference to Fig. 15. With a predetermined value in Fig. 15 as the first temperature, when the first temperature detection means 630 (TH2) detects the first temperature, the first blowing means (fan) 44, which is the blowing means on one end side described in Fig. 19, starts blowing air. At this time, the maximum blowing volume of the fan 44 is 30%, assuming that it is 100%. Furthermore, when the first temperature detection means 630 (TH2) detects a third temperature (between the predetermined value and the predetermined value + 10°C in Fig. 15) which is higher than the first temperature, the blowing volume of the first blowing means 44 increases.

[0052] When the first temperature detection means 630 (TH2) detects a fourth temperature that is higher than the first temperature and lower than the third temperature, the amount of air sent by the first blowing means 44 is smaller than when the third temperature is detected. In this manner, the amount of air sent by the first blowing means 44 is based on the temperature detected by the first temperature detection means (TH2).

[0053] When the temperature detected by the first temperature detection means (TH2) is a second temperature that is smaller than the predetermined value (first temperature) in Fig. 15, the first blowing means does not blow air. When the temperature is lower than the first temperature, it is determined that the temperature of the fixing film 603 is not excessively high. Therefore, cooling by the blowing means is not necessary.

[0054] When the temperature detected by the first temperature detection means (TH2) is equal to or higher than the predetermined value +10° C. in FIG. 15, the amount of air sent by the first air sending means 44 becomes maximum.

[0055] Similarly, the strength of the fan motor M3 (the other end portion) is controlled according to the detection result (detected temperature) of the second temperature detection means 630 (TH3).

[0056] The flowchart in FIG. 14 is a flowchart related to the operation of the fan motor M3 (the other end portion).

[0057] A specific procedure will be described with reference to the flow chart of FIG. 14. When a print signal is received, the heater 600 starts to be energized, the pressure roller 70 is rotated via the fixing drive motor M1, and the fixing film 603 is heated (S001). When the fixing film 603 or the heater 600 reaches the target temperature, paper feed is started (S002). The control circuit unit 90 judges whether the detection result of the second temperature detection means 630 (TH3) has reached the first temperature (S003: Yes). When the detection temperature of the second temperature detection means 630 (TH3) has reached the first temperature (S003: Yes), the control circuit unit 90 drives the fan motor M3 (other end) to start cooling the other end (S004). When the detection result of the second temperature detection means 630 (TH3) has not reached the first temperature (S003: No), it judges whether the job is completed (S007).

[0058] When cooling of the other end portion is performed, the control circuit unit 90 judges whether the detection result of the second temperature detection means 630 (TH3) is below the first temperature (S005). When the detection result of the second temperature detection means 630 (TH3) is below the first temperature (Yes in S005), the control circuit unit 90 stops driving the fan motor M3 (one end portion) and stops cooling of the other end portion (S006). When the detection result of the second temperature detection means 630 (TH3) is not below the first temperature (No in S005), the control circuit unit 90 continues driving the fan motor M3 (other end portion) and continues cooling of the other end portion (S004).

[0059] In S007, it is determined whether the job has been completed, and if it has been completed (Yes in S007), the operation of the image forming apparatus is stopped. If it has not been completed (No in S007), paper passing is continued (S002).

[0060] 13 and 14, the first blower 44L is controlled based on the detection result of the first temperature detector TH2, regardless of the detection result of the second temperature detector TH3. Similarly, the second blower 44R is controlled based on the detection result of the second temperature detector TH3, regardless of the detection result of the first temperature detector TH2.

[0061] There is a state in which the first blower means 44L blows air and the second blower means 44R does not blow air. This is when the temperature detected by the first temperature detection means 630 (TH2) is equal to or higher than the first temperature, and the temperature detected by the second temperature detection means 630 (TH3) is equal to the second temperature (lower than the first temperature). There is also a state in which the first blower means 44L does not blow air and the second blower means 44R blows air. This is when the temperature detected by the first temperature detection means 630 (TH2) is equal to the second temperature (lower than the first temperature), and the temperature detected by the second temperature detection means 630 (TH3) is equal to the first temperature. There is also a state in which the first blower means 44L and the second blower means 44R blow air. This is when the temperatures detected by the first temperature detection means 630 (TH2) and the second temperature detection means 630 (TH3) are equal to or higher than the first temperature. When the temperatures detected by the first temperature detecting means 630 (TH2) and the second temperature detecting means 630 (TH3) are the second temperature, air is not blown.

[0062] As shown in FIG. 19, the blower mechanism 800 has a fan 44 at each of both ends of the heating unit 60. Furthermore, there are two fans on one end side and two on the other end side. The two fans 44 on the one end side are controlled in the same way, and the two fans 44 on the other end side are controlled in the same way. In this embodiment, a shutter 47 is provided, and the shutter is moved according to the size of the recording material in the width direction to determine the opening width of the air outlet 46. Since the cooling range can be determined by the shutter, the multiple fans 44 on one side may be controlled in the same way. In addition, it is preferable to control the multiple fans 44 on one side in the same way, because the number of thermistors can be reduced and there is no need to set up a complicated control.

[0063] Following the flow in Figures 13 and 14, printing was carried out under the following conditions.

[0064] The main body conveying speed was 260 mm / s, the print speed was 60 sheets / min, and the paper type was CS068 (A4R size). Furthermore, the cooling fan start temperature was the temperature control temperature + 5°C, the paper passing conditions were: 5 sheets were passed continuously and then stopped for 5 seconds repeatedly, the paper register (paper misalignment): the paper was shifted 1 mm toward one end, and the number of prints was 100,000 sheets. The temperature transition from the start of the paper passing job to 80 seconds (51 sheets of A4R size) is shown in Figures 16 and 17. Before the present invention was implemented, the temperature transition was as shown in Figure 16, but it became as shown in Figure 17. Before the implementation, the temperature difference between the paper passing area and the non-paper passing area was around 20°C, while after the implementation of this embodiment, it was around 5°C. In order to quantitatively evaluate the wear of the fixing film surface layer before and after the implementation of this embodiment, the surface layer thickness was measured after 100,000 sheets were passed. Before implementing this embodiment, the amount of wear was 1 μm, but after implementing this embodiment, it was confirmed that the amount of wear was reduced to 0.81 μm. By implementing this embodiment, the temperature difference between the paper passing area and the non-paper passing area was reduced, and as a result of the reduced temperature difference, it was confirmed that the surface layer wear life was extended by 1.23 times.

[0065] In addition, by adopting this embodiment, it is possible to reduce the temperature difference between one end and the other end as can be seen from Figures 16 and 17. This makes it possible to prevent either one end or the other end from being excessively cooled or from being insufficiently cooled. As a result, it is possible to control the fixing film 603 to an appropriate temperature, suppress the occurrence of downtime, and suppress the decrease in productivity.

[0066] <Example 2> In this embodiment, whether or not to independently drive the cooling means is selected depending on the longitudinal size (width) of the paper.

[0067] The temperature detection means (TH2) 630 is provided to detect the maximum value of the temperature rise in the non-paper passing area or to predict the maximum value (detect the approximately maximum value). However, depending on the combination of the position of the temperature detection means (TH2) 630 and the longitudinal size of the paper, there are cases where the maximum value of the temperature rise in the non-paper passing area cannot be detected or predicted. For example, this may be the case when the longitudinal size of the paper is larger than the position of the temperature detection means (when the temperature detection means does not become a non-paper passing area) or when the edge of the paper is far away from the position of the temperature detection means. Also, this may be the case when the temperature detection means in the non-paper passing area is only present at one end or the other end.

[0068] Fig. 18 is a flow chart diagram in this embodiment. When a print signal is received, it is determined whether the paper size is subject to independent drive (S008). If it is subject, the process proceeds to S001 in Figs. 13 and 14, and thereafter, the operation is performed in accordance with the flow charts in Figs. 13 and 14 (see Example 1 for an explanation of the flow charts in Figs. 13 and 14). If it is not subject to independent drive, one end and the other end are driven simultaneously (S009). The drive timing may be when paper starts to pass, after a predetermined number of sheets have passed, or when a separately provided temperature detection means reaches a predetermined temperature or higher. [Explanation of symbols]

[0069] 1. Image forming device 40 Fixing device 44 Fans 45 Duct 46 Ventilation vent 47 Shutter 60 Heating Unit 600 Heater 601 Heater holder 602 Support stay 603 Fixing film 630 Thermistor

Claims

1. A heating unit that applies heat to the recording material, A pressurized rotating body that contacts the heating unit and forms a nip portion, The pressurized rotating body, together with the heating unit, clamps and transports the recording material to fix the toner image onto the recording material. A first blowing means for blowing air to one end of the heating unit in the width direction perpendicular to the transport direction of the recording material, In the width direction, a second blowing means for blowing air to the other end of the heating unit, A first temperature detection means for detecting the temperature of one end of the heating unit, A second temperature detection means for detecting the temperature of the other end of the heating unit, A control unit controls the first air blower and the second air blower based on the temperature detection by the first temperature detection means and the second temperature detection means, The first state in which the first blowing means and the second blowing means are blowing air, A second state in which the first blowing means is blowing air and the second blowing means is not blowing air, A third state occurs in which the first blower does not blow air and the second blower does, The control unit increases the amount of air blown by the first air blower in accordance with the temperature detected by the first temperature detection means becoming higher than the first temperature in the first state and the second state. A fixing device characterized in that, in the first state and the third state, the amount of air blown by the second air blower can be increased in accordance with the temperature detected by the second temperature detection means becoming higher than the first temperature.

2. If the temperature detected by the first temperature detection means is the first temperature and the temperature detected by the second temperature detection means is a second temperature lower than the first temperature, the first air blower will blow air, and the second air blower will not blow air. If the temperature detected by the first temperature detection means is the second temperature, and the temperature detected by the second temperature detection means is the first temperature, the first air blower does not blow air, and the second air blower does blow air. The fixing device according to feature 1.

3. The fixing apparatus according to claim 1, characterized in that the first temperature detection means and the second temperature detection means detect the temperature of the maximum paper-feeding area of ​​the recording material in the width direction.

4. In the width direction, the first temperature detection means and the second temperature detection means are arranged symmetrically with respect to the center of the paper feeding area of ​​the recording material. The fixing device according to feature 3.

5. It has a third temperature detection means for detecting the temperature of the heating unit, The first temperature detection means is positioned at the end closest to the other end among the multiple temperature detection means. The fixing device according to claim 4, characterized in that the second temperature detection means is positioned at the far end among the multiple temperature detection means.

6. In the width direction, a first duct has a first air outlet corresponding to one end of the heating unit, and guides the air blown by the first air blowing means to the one end of the heating unit. The heating unit is further provided with a second duct having a second air outlet in the width direction corresponding to the other end of the heating unit, and guiding the air blown by the second air blowing means to the other end of the heating unit. The fixing device according to feature 1.

7. In the aforementioned nip section, the recording material is transported vertically from below to above. The fixing device according to feature 1.

8. A first shutter that opens and closes the first air outlet, The system includes a second shutter that opens and closes the second air outlet. The fixing device according to feature 6.

9. The first blowing means and the second blowing means each have a fan. The fixing device according to feature 1.

10. The first blowing means has a plurality of fans, The second blowing means has a plurality of fans, If the temperature detected by the first temperature detection means is the first temperature and the temperature detected by the second temperature detection means is a second temperature lower than the first temperature, the multiple fans of the first air blower will blow air, and the multiple fans of the second air blower will not blow air. If the temperature detected by the first temperature detection means is the second temperature, and the temperature detected by the second temperature detection means is the first temperature, the multiple fans of the first air blower do not blow air, and the multiple fans of the second air blower do blow air. The fixing device according to feature 9.

11. A heating unit that applies heat to the recording material, A pressurized rotating body that contacts the heating unit and forms a nip portion, The pressurized rotating body, together with the heating unit, clamps and transports the recording material to fix the toner image onto the recording material. A first blowing means for blowing air to one end of the heating unit in the width direction perpendicular to the transport direction of the recording material, In the width direction, a second blowing means for blowing air to the other end of the heating unit, A first temperature detection means for detecting the temperature of one end of the heating unit, A second temperature detection means for detecting the temperature of the other end of the heating unit, A control unit controls the first air blower and the second air blower based on the temperature detection by the first temperature detection means and the second temperature detection means, When the first and second blowing means are blowing air, if the temperature detected by the first temperature detection means is the third temperature and the temperature detected by the second temperature detection means is a fourth temperature lower than the third temperature, then the amount of air blown by the first blowing means is greater than the amount of air blown by the second blowing means. A fixing device characterized by the following features.

12. If the temperature detected by the first temperature detection means is the same as or higher than the first temperature which is lower than the fourth temperature, the first air blower will blow air. The fixing apparatus according to claim 11, characterized in that the first blower blows air when the temperature detected by the second temperature detection means is equal to or greater than the first temperature.

13. The fixing device according to claim 11, characterized in that the maximum airflow rate of the first air blowing means and the second air blowing means are the same.

14. If the temperature detected by the first temperature detection means is a second temperature lower than the first temperature, the first air blower does not blow air. The fixing apparatus according to claim 12, characterized in that if the temperature detected by the second temperature detection means is the second temperature, the second air blowing means does not blow air.

15. The fixing apparatus according to claim 11, characterized in that the first temperature detection means and the second temperature detection means detect the temperature of the maximum paper-feeding area of ​​the recording material in the width direction.

16. In the width direction, the first temperature detection means and the second temperature detection means are arranged symmetrically with respect to the center of the paper feeding area of ​​the recording material. The fixing device according to claim 15.

17. It has a third temperature detection means for detecting the temperature of the heating unit, The first temperature detection means is positioned at the end closest to the other end among the multiple temperature detection means. The fixing device according to claim 16, characterized in that the second temperature detection means is positioned at the far end among the multiple temperature detection means.

18. In the width direction, a first duct has a first air outlet corresponding to one end of the heating unit, and guides the air blown by the first air blowing means to the one end of the heating unit. The heating unit is further provided with a second duct having a second air outlet in the width direction corresponding to the other end of the heating unit, and guiding the air blown by the second air blowing means to the other end of the heating unit. The fixing device according to feature 11.

19. In the aforementioned nip section, the recording material is transported vertically from below to above. The fixing device according to feature 11.

20. A first shutter that opens and closes the first air outlet, The system includes a second shutter that opens and closes the second air outlet. The fixing device according to claim 18.

21. The first blowing means and the second blowing means each have a fan. The fixing device according to feature 11.

22. The first blowing means has a plurality of fans, The second blowing means has a plurality of fans, The fixing device according to claim 21, characterized in that the airflow rates of the fans of the first blowing means are the same, and the airflow rates of the fans of the second blowing means are the same.

23. A heating unit that applies heat to the recording material, A pressurized rotating body that contacts the heating unit and forms a nip portion, The pressurized rotating body, together with the heating unit, clamps and transports the recording material to fix the toner image onto the recording material. A first blowing means for blowing air to one end of the heating unit in the width direction perpendicular to the transport direction of the recording material, In the width direction, a second blowing means for blowing air to the other end of the heating unit, A first temperature detection means for detecting the temperature of one end of the heating unit, A second temperature detection means for detecting the temperature of the other end of the heating unit, The first air blowing means is controlled based on the temperature detected by the first temperature detection means, regardless of the temperature detected by the second temperature detection means. A fixing device characterized by having a control unit that controls the second air blowing means based on the temperature detected by the second temperature detection means, regardless of the temperature detected by the first temperature detection means.

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