JP2020071357A - Fixing device and image forming apparatus equipped with the same - Google Patents

Abstract

To provide a fixing device and an image forming apparatus, which prevent occurrence of fixing failure while keeping optimum temperature balance at an end part of a fixing film due to temperature rise of a non-paper passing part.SOLUTION: Based on a heating member, a fixing member, a pressuring member, temperature detecting means at the center part and an end part, and the end part temperature, a fixing device includes: a first fan for cooling one end part area; a second fan for cooling the other end part area different from the first fan; a first shutter for changing the cooling width by the first fan; and a second shutter for changing the cooling width by the second fan. Based on the temperature detected by the temperature detection means at the end part, the opening widths of the first shutter and the second shutter are respectively controlled.SELECTED DRAWING: Figure 9

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus, such as a copying machine or a printer, equipped with a fixing device that fixes an unfixed image on a recording material.

  The fixing device generally includes a fixing device for fixing the unfixed image carried on the recording medium to the recording medium, a hypothetical fixing device for temporarily fixing the unfixed image on the recording medium, and a recording medium carrying the fixed image. It has been put to practical use as a surface modification device for modifying the surface property.

  For the sake of convenience, an image heating device (fixing device) that heats and fixes a toner image provided on an image forming apparatus such as a copying machine or a printer on a recording medium will be described as an example.

  In recent years, as a fixing device mounted on an image forming apparatus, a fixing device using a tubular film has been used. This fixing device has a tubular film, a heater that heats the film, and a roller that forms a fixing nip portion together with the film, while conveying a recording material carrying an unfixed toner image in the fixing nip portion. The image is fixed on the recording material by heating. There are advantages that the warm-up time is short and the standby power consumption is small.

  On the other hand, in this fixing device, in the case where a recording material having a small width (hereinafter referred to as a small-sized recording material) is continuously fixed, the temperature of a portion where the recording material does not pass (non-sheet passing portion) rises excessively. Phenomenon = It is known that the phenomenon of temperature rise in the non-sheet passing portion is likely to occur.

  Therefore, in Patent Documents 1 and 2, there is provided a cooling fan for blowing air to the non-sheet passing portion of the fixing unit to cool it, and the blowing area of the cooling fan is set to the width of the recording material by moving the shutter. An image forming apparatus that can be adjusted accordingly is disclosed. The cooling fan is controlled in accordance with the temperature detected by a temperature detection member provided in a blowable region of the non-sheet passing portion of the film or the heater.

JP, 2013-134421, A JP, 2018-36490, A

  In the image forming apparatus, the temperature balance at the end of the fixing film may be lost (one end: high temperature, opposite end: low temperature). Specifically, even if the paper type set by the operation unit or printer driver is the same, the temperature of the non-sheet-passing part rises due to the variation in the longitudinal position when setting the recording material for each paper feed cassette. Change will occur. In addition, the temperature of the non-sheet passing portion rises due to variations in the longitudinal temperature of the fixing film.

  However, in the fixing device described in the prior art document 1, the blower area of the cooling fan is adjusted by moving the shutter, but since the moving amount of the shutter is the same, the blower areas are the same. Will be changed to. As a result, the temperature of the non-sheet passing area is originally adjusted so that the temperature of the fixing film at one end is noticeably higher than that at the opposite end, and the air volume of the cooling fan is adjusted and blown, so the temperature of the fixing film at the opposite end decreases. Then, there arises a problem that fixing failure occurs.

  An object of the present invention is to provide a fixing device and an image forming apparatus that prevent the occurrence of a fixing failure while optimally maintaining the temperature balance of the end portion of the fixing film due to the temperature rise in the non-sheet passing portion.

  The present invention is a fixing device having the following configuration.

The fixing device of the present invention includes a heating member that heats a recording material carrying an unfixed image by supplying electric power from a power source, a fixing member that contacts the unfixed image of the recording material, and a heating member through the fixing member. A pressure member that presses against the member to form a nip region and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means are provided at the center and both ends, respectively. Based on the temperature detected by the temperature detecting means, the control means for controlling the power supply from the power source to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the temperature detecting means at the end portion A first fan that cools one end region based on the temperature, a second fan that cools the other end region different from the first fan, and a first fan that changes the cooling width by the first fan. 1 shutter, 2nd A second shutter for changing the cooling width by the fan,
The opening width of each of the first shutter and the second shutter is controlled based on the temperature detected by the temperature detecting means at the end.

As the fixing device of the present invention, a heating member that heats a recording material carrying an unfixed image by supplying power from a power source, a fixing member that contacts the unfixed image of the recording material, and a heating member through the fixing member. A pressure member that presses against the member to form a nip region and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means are provided at the center and both ends, respectively. Based on the temperature detected by the temperature detecting means, the control means for controlling the power supply from the power source to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the temperature detecting means at the end portion A first fan that cools one end region based on the temperature, a second fan that cools the other end region different from the first fan, and a first fan that changes the cooling width by the first fan. 1 shutter, A second shutter for changing the cooling width by 2 fans,
The opening widths of the first shutter and the second shutter are respectively controlled according to the position of the recording material in the cassette with respect to the fixing device.

The fixing device of the present invention includes a heating member that heats a recording material carrying an unfixed image by supplying electric power from a power source, a fixing member that contacts the unfixed image of the recording material, and a heating member through the fixing member. A pressure member that presses against the member to form a nip region and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means are provided at the center and both ends, respectively. Based on the temperature detected by the temperature detecting means, the control means for controlling the power supply from the power source to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the temperature detecting means at the end portion A first fan that cools one end region based on the temperature, a second fan that cools the other end region different from the first fan, and a first fan that changes the cooling width by the first fan. 1 shutter, 2nd A second shutter for changing the cooling width by the fan,
The opening widths of the first shutter and the second shutter are respectively controlled according to a plurality of Th temperature information abutting on the fixing member at the time of confirming the temperature rise when assembling the fixing device. ..

  According to the fixing device of the present invention, even if the temperature balance of the end portion of the fixing film is lost due to the temperature rise in the non-sheet passing portion, the temperature balance of the end portion of the fixing film can be controlled by independently driving the shutter of the cooling fan. Can be maintained optimally, and the occurrence of defective fixing can be eliminated.

Schematic cross-sectional view of an image forming apparatus equipped with a fixing device according to an embodiment Schematic cross-sectional view of the fixing device according to the embodiment Schematic front view of the fixing device according to the embodiment Schematic diagram of the layer structure of the film according to the example Schematic cross-sectional view of a heater according to an embodiment and a block diagram of a control system The figure which shows the shutter independent drive which concerns on an Example. Drive configuration diagram of a shutter according to an embodiment Conventional film temperature transition diagram according to Example Flowchart diagram according to the first embodiment The figure after the shutter independent drive according to the embodiment The film temperature transition diagram of the present embodiment according to the embodiment Conventional film temperature transition diagram according to Example 2 Flowchart diagram according to the second embodiment

  Embodiments of the present invention will be described with reference to the accompanying drawings. In the following embodiments, a laser beam printer using an electrophotographic process will be described as an example.

  Hereinafter, the present invention will be described by way of examples with reference to the drawings.

[Example 1]
(1) Image Forming Section FIG. 1 is a schematic diagram showing a schematic configuration of a laser beam printer as an image forming apparatus according to the present embodiment, which is equipped with a fixing device.

  First, the outline of the image forming unit will be described. This printer can perform an image forming operation according to image information from an external host device 200 communicatively connected to a control circuit unit (control unit) 100 to form a full-color image on a recording material and output it. .. The control circuit unit 100 in this embodiment is a central processing unit (CPU).

  The external host device 200 is a computer, an image reader, or the like. The control circuit unit 100 exchanges signals with the external host device 200. Also, it exchanges signals with various image forming devices and controls image forming sequence.

  Reference numeral 8 denotes an endless and flexible intermediate transfer belt (hereinafter abbreviated as a belt), which is stretched between a secondary transfer counter roller 9 and a tension roller 10, and the roller 9 is driven. Is driven to rotate counterclockwise by the arrow at a predetermined speed. A secondary transfer roller 11 is pressed against the secondary transfer counter roller 9 via the belt 8. The contact portion between the belt 8 and the secondary transfer roller 11 is the secondary transfer portion.

  Reference numerals 1Y, 1M, 1C, and 1Bk are four image forming units, that is, first to fourth image forming units, and are arranged in a line below the belt 8 along the belt moving direction at predetermined intervals. Each image forming unit is a laser exposure type electrophotographic process mechanism, and a drum type electrophotographic photosensitive member (hereinafter abbreviated as a drum) as an image bearing member that is rotationally driven in the clockwise direction of an arrow at a predetermined speed. ) 2. Around the drum 2, a primary charger 3, a developing device 4, a transfer roller 5 as a transfer unit, and a drum cleaner device 6 are arranged. Each transfer roller 5 is arranged inside the belt 8 and is brought into pressure contact with the corresponding drum 2 via the belt 8 on the lower going side. A contact portion between each drum 2 and the belt 8 is a primary transfer portion. Reference numeral 7 denotes a laser exposure device for the drum 2 of each image forming unit, which is composed of a laser emitting means for emitting light corresponding to a time series electric digital pixel signal of given image information, a polygon mirror, a reflection mirror and the like.

  The control circuit unit 100 operates each image forming unit based on the color separated image signal input from the external host device 200. As a result, in the first to fourth image forming units 1Y, 1M, 1C, and 1Bk, yellow, magenta, cyan, and black color toner images (undetermined) are set at predetermined control timing with respect to the surface of the rotating drum 2. The formed toner image) is formed. The description of the electrophotographic image forming principle and process for forming a toner image on the drum 2 is omitted. The above-mentioned toner image formed on the surface of the drum 2 of each image forming unit is rotationally driven at the primary transfer portion in the forward direction with respect to the rotational direction of each drum 2 and at a speed corresponding to the rotational speed of each drum 2. The images are sequentially transferred onto the outer surface of the belt 8 that is being transferred. As a result, an unfixed full-color toner image is compositely formed on the surface of the belt 8 by superimposing the above four toner images.

  On the other hand, at a predetermined paper feed timing, the paper feed of the paper feed cassette of the selected stage among the upper and lower multi-stage cassette paper feed units 13A, 13B, and 13C in which the recording materials P of various sizes of various sizes are stacked and stored. The roller 14 is driven. As a result, one sheet of the recording material P stacked and stored in the sheet feed cassette at that stage is separated and fed, and is conveyed to the registration rollers 16 through the vertical conveyance path 15. When manual paper feed is selected, the paper feed roller 18 is driven. As a result, one sheet of recording material stacked and set on the manual feed tray (multi-purpose tray) 17 is separated and fed, and is conveyed to the registration rollers 16 through the vertical conveyance path 15.

  The registration roller 16 moves the recording material P so that the leading end of the recording material P reaches the secondary transfer portion at the timing when the leading end of the full-color toner image on the rotating belt 8 reaches the secondary transfer portion. Timing transfer. As a result, the full-color toner images on the belt 8 are secondarily transferred to the surface of the recording material P collectively at the secondary transfer portion. An image forming unit is a component necessary for secondarily transferring the toner image onto the recording material. The recording material that has passed through the secondary transfer portion is separated from the surface of the belt 8, guided by the vertical guide 19, and introduced into the fixing device (fixing device) 20. The fixing device 20 melts the toner images of the plurality of colors and fixes them on the recording material. The recording material exiting the fixing device 20 passes through a transport path 21 and is discharged onto a paper discharge tray 23 by a paper discharge roller 22. The surface of the belt 8 after the recording material is separated at the secondary transfer portion is cleaned by the belt cleaning device 12 after removal of residual adhering materials such as secondary transfer residual toner, and is repeatedly used for image formation. In the monochrome print mode, only the fourth image forming unit Bk that forms a black toner image is controlled. When the double-sided print mode is selected, the recording material on which the first side is printed is sent out onto the paper output tray 23 by the paper output roller 22 and before the rear end passes through the paper output roller 22. The rotation of the paper discharge roller 22 is converted into reverse rotation. As a result, the recording material is switched back and introduced into the re-conveyance path 24. Then, the sheet is turned upside down and conveyed again to the registration roller 16. After that, as in the case of printing the first side, the sheet is conveyed to the secondary transfer unit and the fixing device 20 and discharged onto the sheet discharge tray 23.

(2) Fixing Unit In the following description, the longitudinal direction of the fixing device or members constituting the fixing device is a direction that is parallel to the direction orthogonal to the recording material conveyance direction in the recording material conveyance path surface. Regarding the fixing device, the front is the surface on the recording material introduction side, and the left and right are the left or right when the device is viewed from the front. The width of the recording material is the dimension of the recording material in the direction orthogonal to the recording material conveying direction on the surface of the recording material.

  FIG. 2 is a schematic diagram of the fixing device (fixing unit) 20A and the blowing unit 20B according to the present embodiment. FIG. 3 is a schematic front view of the fixing unit 20A. The blower unit 20B will be described later.

  Reference numeral 31 denotes a film assembly, which includes a tubular film 33 as a heating rotator, a gutter-shaped cross-section guide member 34 having heat resistance and rigidity, and a heater 35. The heater 35 is supported on the outer surface of the guide member 34 by a recess provided along the longitudinal direction of the guide member 34. The film 33 is loosely fitted onto the guide member 34 to which the heater 35 is attached. The film assembly 31 further includes a stay 36 as a reinforcing member having a U-shaped cross section, and end holders 37 fitted to the outwardly projecting arm portions 36a at the left and right ends of the stay 36, respectively. The end holder 37 has a flange portion 37 a that comes into contact with the end surface of the film 33 in the longitudinal direction.

  Reference numeral 32 denotes a pressure roller as a pressure member, which has a cored bar 32a and an elastic layer 32b such as silicone rubber formed outside the cored bar 32a. The pressure roller 32 may be configured to have a fluororesin layer 32c such as PTFE (polytetrafluoroethylene) or PFA (perfluoroalkoxyalkane) outside the elastic layer 32b in order to improve the surface property. .. The pressure roller 32 is rotatably supported at both ends of the cored bar 32a between the left and right side plates of a device frame (not shown) via bearing members.

  The film assembly 31 is arranged so that the heater 35 side faces the pressure roller 32, and the pressure spring is provided between the left and right end holders 37 and the left and right fixed spring receiving members 39 of the device frame (not shown). 40 is contracted. As a result, the stay 36, the guide member 34, and the heater 35 are urged against the pressure roller 32. The biasing force is set to a predetermined value and the heater 35 is pressed against the pressure roller 32 with the film 33 sandwiched between the film 33 and the pressure roller 32, and a fixing nip having a predetermined width in the recording material conveyance direction is provided. The part N is formed.

  The film 33 has a three-layer composite structure including a base layer 33a, an elastic layer 33b, and a release layer 33c in order from the inner surface side to the outer surface side, as shown in FIG. As the base layer 33a, a heat resistant film having a film thickness of 100 μm or less, preferably 50 μm or less and 20 μm or more can be used in order to reduce the heat capacity and improve the quick start property. For example, films of Ni, SUS, polyimide, polyimide amide, PEEK, PES, PPS, PTFE, PFA, FEP, etc. can be used. In this example, a tubular Ni film having a diameter of 30 mm was used. The elastic layer 33b has a rubber hardness of 10 degrees (JIS-A), a thermal conductivity of 4.18605 × 10 −1 W / m · ° C. (1 × 10 −3 [cal / cm.sec.deg]), and a thickness of 300 μm. Silicone rubber was used. As the release layer 33c, a PFA tube layer having a thickness of 20 μm was used. The PFA coat layer may be selectively used depending on the case.

  The heater 35 is a plate-shaped member having a low heat capacity, which is long in the direction orthogonal to the conveyance direction of the recording material P. FIG. 5 is a schematic sectional view and control system diagram of the heater 35. The heater 35 has a substrate 35a, a heating resistance layer 35b formed on the substrate 35a, and a protective layer 35c. The substrate 35a is made of ceramic such as aluminum nitride. The heating resistance layer 35b is made of an electric resistance material such as Ag / Pd (silver / palladium) having a thickness of about 10 μm and a width of 1 to 5 mm on the surface of the heater substrate 35a opposite to the surface in contact with the film 33 by screen printing or the like. Is formed. The protective layer 35c is formed of glass, fluororesin, or the like so as to cover the heating resistance layer 35b. In this embodiment, a sliding member (lubricating member) 35d is provided on the surface of the heater substrate 35a that contacts the film 33.

  The heater 35 is supported by exposing the heater substrate surface side provided with the sliding member 35d in a groove formed along the longitudinal direction at a substantially central portion of the outer surface of the guide member 34. In the fixing nip portion N, the surface of the sliding member 35d of the heater 35 and the inner surface of the film 33 make contact and slide. Then, the rotating film heating film 33 is heated by the heater 35.

  By supplying electric power to the heat generation resistance layer 35b of the heater 35, the heat generation resistance layer 35b generates heat and the heater 35 rises in temperature over the entire effective heat generation width A in the heater longitudinal direction. The thermistor TH1 provided on the heater 35 detects the temperature of the heater 35. Further, the output (signal value related to temperature) of the thermistor TH4 provided on the inner surface of the film 33 is input to the control circuit unit 100 via the A / D converter. Based on the input temperature information, the control circuit unit 100 supplies the power supplied from the power supply (power supply unit, heater drive circuit unit) 101 to the heating resistance layer 35b so that the temperature of the thermistor TH4 is maintained at the target temperature. Is controlled.

  The pressure roller 32 is rotated in the direction of the arrow (counterclockwise) shown in FIG. 2 by the motor (driving source) M1. The rotational force acts on the film 33 by the frictional force in the fixing nip portion N between the pressure roller 32 and the outer surface of the film 33 due to the rotational driving of the pressure roller 32. As a result, the film 33 rotates around the guide member 34 in the counterclockwise direction indicated by the arrow while the inner surface of the film 33 slides in close contact with the heater 35 in the fixing nip portion N. The film 33 rotates at a peripheral speed substantially corresponding to the peripheral speed of rotation of the pressure roller 32. The left and right flange portions 37a serve to receive the film end portions on the side of the shift when the rotating film 33 shifts to the left or right along the length of the guide member 34 and regulate the shift. In order to improve the slidability between the heater 35 and the film 33 in the fixing nip portion N, a sliding member 35d is provided on the heater surface, and a lubricant such as heat resistant grease is interposed between the sliding member 35d and the inner surface of the film 33. Let Then, based on the print start signal, the rotation of the pressure roller 32 is started, and the power supply to the heater 35 is started. When the rotational peripheral speed of the film 33 becomes steady and the temperature of the heater 35 reaches a predetermined temperature, the recording material P carrying the toner image t in the fixing nip portion N has the toner image carrying surface side with the film 33 side. be introduced. The recording material P is in close contact with the heater 35 via the film 33 in the fixing nip portion N and moves in the fixing nip portion N together with the film 33. In the process, the toner image t is heated and fixed on the surface of the recording material P by the heat of the film 33. The recording material P that has passed through the fixing nip portion N is separated from the surface of the film 33 and discharged.

  The recording material P is conveyed in such a manner that the center of the recording material in the width direction is aligned with the conveyance reference of the apparatus. The conveyance reference of the apparatus of this embodiment is the center of the apparatus in the width direction of the recording material, and is configured to perform so-called center reference conveyance. Therefore, when a recording material having a width narrower than the maximum recording material usable in the apparatus (hereinafter referred to as a small-sized recording material) is conveyed, non-sheet passing areas are formed at both ends of the small-sized recording material. In this embodiment, since the longitudinal center of the fixing film 33 also coincides with the transport reference position of the apparatus, the recording material is transported so that the widthwise center of the recording material is aligned with the longitudinal center of the fixing film 33. Become. S is a conveyance reference line (virtual line) of the recording material.

(3) Temperature Detection Section The position of the thermistor as a temperature detection member for detecting the temperature of the heater 35 or the film 33 will be described with reference to FIG. The thermistor TH1 is provided so as to detect the temperature of the area of the heater 35 through which all the recording materials used in the image forming apparatus pass. The electric power supplied to the heater 35 is controlled according to the temperature detected by the thermistor TH4. In the present embodiment, the thermistor TH1 is provided at the center of the heater 35 in the longitudinal direction. The thermistors TH2 and TH3 are provided between the center and the end position of the heater 35 in the longitudinal direction. TH4 is arranged at the center of the inner surface of the film 33, and TH5 and TH6 are respectively arranged at the end of the inner surface of the film 33. The film 33 is provided so as to detect the temperatures of the central portion of the film and the non-sheet passing area of the recording material. The detection information (signal value regarding temperature) of the thermistors TH1, TH2, TH3, TH4, TH5, and TH6 is input to the control circuit unit 100 via the A / D converter.

  Although the thermistors TH1, TH2, and TH3 are provided so as to detect the temperature of the heater 35 in this embodiment, the present invention is not limited to this. The temperature of the inner surface of the film 33 may be detected. Although the thermistors TH4, TH5, and TH6 are provided so as to detect the temperature of the inner surface of the film 33, they are not limited to this. It may be provided so as to detect the temperature of the heater 35.

(4) Blower Unit The blower unit 20B according to this embodiment will be described with reference to FIGS. 2 and 7. The blower unit 20B is provided to suppress the temperature rise in the non-sheet passing portion of the film 33, which occurs when the small-sized recording material is continuously fixed, by the blower. The blower unit 20B includes a fan 41 and a duct 42 that guides the wind of the fan 41. The duct 42 has an opening portion 43, and the opening portion 43 is provided at a position facing the end portion of the film 33 which becomes a non-sheet passing area when fixing processing of a small size recording material. The wind of the fan 41 is guided to the end portion of the film 33 through the opening 43. The blower unit 20B has a shutter 44 as an adjusting member that adjusts the opening width of the opening 43 according to the width of the recording material used, and a shutter drive unit (not shown) that drives the shutter 44.

  The fan 41, the duct 42, the opening 43, and the shutter 44 are symmetrically arranged in the longitudinal direction of the film 33. Although an axial fan is used as the fan 41 in this embodiment, a centrifugal fan such as a sirocco fan may be used.

  Here, the drive configuration of the shutter 44 will be described. The shutter drive unit 45 has a support plate 46, rack teeth 47, pinion gears 48, and a motor M2. The two left and right shutters 44 are supported so as to be slidable in the left-right direction along the plate surface of the support plate 46 that has the opening 43 and extends in the left-right direction. The shutter 44 is communicated with the rack teeth 47 and the pinion gear 48, and the pinion gear 48 is normally and reversely rotated by the forward and reverse drive of the motor (pulse motor) M2. By rotating the pinion gear 48 in the forward and reverse directions, the two shutters 44 can be independently opened and closed with respect to the corresponding openings 43. The two left and right openings 43 are provided so as to open in the range of 1116 mm to 165 mm from the longitudinal center. The left and right shutters 44 are configured to be able to close (close) the opening 43 by a predetermined amount from the longitudinal center of the support plate 46 toward the outside.

  Next, the control of the blower unit 20B will be described with reference to FIG. Information W regarding the width (size) of the recording material is input to the control circuit unit 100 from a user input or an automatic detection mechanism for the width of the recording material provided in the paper feed cassette 13 or the manual feed tray 17. Then, the control circuit unit 100 drives the motor M2 and moves the shutter 44 to adjust the opening width of the opening 43 based on the information W on the width of the recording material. The control circuit unit 100 controls the shutter drive unit 45 when the recording material (SR-A3 size in this embodiment) has the maximum width that can be used in the apparatus, so that the opening 43 is formed as shown in FIG. The shutter 44 is moved to the fully closed position where it is sufficiently closed by the shutter 44. In the case of a small size recording material having a width smaller than that of the SR-A3 size, the left and right shutter opening widths are changed according to the paper size.

(5) Paper Conveyance Position Detection Method In order to detect the longitudinal conveyance position, irradiation position information of the laser scanner 7 on the photosensitive drum 2 in the longitudinal direction is used. Information on the laser irradiation adjustment value is stored in the control circuit unit 100 of the image forming apparatus. In this embodiment, the laser irradiation reference position in the longitudinal direction is stored as α, and the adjustment amount from the laser irradiation reference position α is stored as Δα in the control circuit unit 100. Δα can be adjusted up to ± 5 mm at 0.5 mm intervals. Therefore, the range of the adjustment value is ± 10.

  The laser irradiation adjustment amount Δα can be set to different values for each paper feed cassette, and can be stored in the control circuit unit 100 respectively. The laser irradiation adjusting means can be implemented in each paper feed cassette at the time of factory shipment, or can be readjusted in a user use environment.

  Next, the characteristic configuration and control of the first embodiment will be described.

In the image forming apparatus, even if the paper type set by the operation unit or the printer driver is the same, the temperature state of the non-sheet passing portion rises due to the variation in the position in the longitudinal direction when setting the recording material for each paper feed cassette. Changes will occur. When the shutter opening width of the fan was moved by the same amount on the left and right in that state, the temperature transition was high at one end and low at the opposite end (FIG. 8). (The above is the condition where Δα is +3 mm.)
As a countermeasure against this, in this embodiment, the cooling fan 41 is independently driven by using the adjustment value Δα from the laser irradiation reference position α, and the shutter position is corrected by the number of motor pulses according to Δα. (Table 1).

  The specific procedure is shown in the flowchart of FIG. First, the print signal is received, the print operation is started (step 1), and the paper information (size / paper feed cassette) is acquired (step 2). After that, the laser irradiation adjustment amount Δα is acquired (step 3, Table 1), and after the change amount of the opening width of each shutter is calculated according to the adjustment width of Δα (step 4), the process proceeds to the printing operation (step 5). During printing, when the TH5orTH6 temperature reaches the end cooling FAN operation start temperature (step 6), the cooling fan operation and each shutter opening operation are started (step 7, 49a and 49b in FIG. 10). After that, the printing operation ends (step 8). Printing was performed under the following conditions according to the above flow. Main body transport speed: 264 (mm / s), print speed: 60 sheets / minute, paper type: CS-680 (A4), Δα = + 6 (front side shutter correction amount +3 mm, back side shutter correction amount -3 mm), printing The number of prints was 500. As a result, the temperature changes as shown in FIG. 11, and the temperature difference between TH4, TH5, and TH6 becomes small. Therefore, it is possible to suppress the temperature rise of the non-sheet passing portion of TH5 and prevent the temperature of TH6 from lowering, and it is possible to obtain the effect of suppressing the fixing failure.

[Example 2]
In the image forming apparatus, there may be variations in the longitudinal temperature distribution of the film due to individual differences in the fixing heater and individual films (there is a possibility that a temperature difference occurs between the left and right thermistor temperatures). (FIG. 12)).

  Therefore, in the present invention, the operation is performed according to the procedure as shown in FIG. When assembling the fixing device in advance (step 9), the longitudinal temperature distribution of the fixing film is acquired and checked. (Step 10) The temperature difference (step 11) between the left and right thermistor temperatures in the temperature distribution information is calculated, and the shutter opening width (correction width) of the end cooling fan is adjusted according to the case where the temperature difference between the left and right thermistors is greater than or equal to a predetermined value (step 12). ) Is calculated (step 13, Table 2).

  A means for shipping the main body after storing (setting) the calculated correction amount in the control circuit section of the main body (step 14) is provided. (Step 15). By doing so, at the same time when the cooling fan starts to blow, the temperature difference between the longitudinal direction and the lateral direction of the fixing film originally held by the fixing device can be eliminated, and the temperature rise of the non-sheet passing portion can be suppressed and the fixing failure can be prevented ( (Not shown).

[Other Examples]
Although the embodiments to which the present invention can be applied have been described above, numerical values such as dimensions and conditions illustrated in each embodiment are merely examples, and the present invention is not limited to these numerical values. Numerical values can be appropriately selected as long as the invention can be applied. Further, the configuration described in the embodiments may be appropriately changed within the scope of applying the invention (for example, the control as in the present embodiment may be performed by using a fixing device of a roller fixing system or an IH fixing system). ..

  The fixing film 33 according to the first exemplary embodiment is not limited to the configuration in which the inner surface of the fixing film 33 is supported by the heater 35 and is driven by the pressure roller 32. For example, it may be a unit system that is bridged over a plurality of rollers and driven by any of the plurality of rollers. However, the configurations of Examples 1 and 2 are desirable from the viewpoint of reducing the heat capacity.

  What forms the fixing film 33 and the nip portion N is not limited to a roller member such as the pressure roller 32. For example, a pressure belt unit in which a belt is stretched over a plurality of rollers may be used.

  The image forming apparatus described using the printer 23 as an example is not limited to an image forming apparatus that forms a monochrome image, but may be an image forming apparatus that forms a color image. Further, the image forming apparatus can be implemented in various applications such as a copying machine, a FAX, and a multi-functional machine having a plurality of these functions, in addition to necessary equipment, equipment, and housing structure.

  The image forming apparatus in the above description is not limited to an apparatus that fixes an unfixed toner image on the sheet P. For example, a device that fixes the semi-fixed toner image on the sheet P or a device that heats the fixed image may be used. Therefore, the heating device 111 as the image forming apparatus may be, for example, a surface heating device that adjusts the gloss and surface property of the image.

1Y, 1M, 1C, 1K image forming unit, 8 belts, 11 secondary transfer roller,
20A fixing unit, 20B air blowing unit, 32 pressure roller, 33 film,
35 heater, 41 fan, 43 opening, 44 shutter,
100 control circuit section, N fixing nip section, P recording material,
TH1 first temperature detecting member, TH2 second temperature detecting member,
TH3 third temperature detection member, TH4 fourth temperature detection member,
TH5 fifth temperature detecting member, TH6 sixth temperature detecting member

Claims (5)

A heating member that heats a recording material that carries an unfixed image by supplying power from a power source, a fixing member that contacts the unfixed image of the recording material, and a nip region that is in pressure contact with the heating member through the fixing member. A pressure member that forms and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means provided at the central portion and both ends, respectively, and detected by the temperature detecting means at the central portion. Based on the temperature, the control means for controlling the power supply from the power supply to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the one end based on the temperature detected by the temperature detecting means at the end. A first fan for cooling the partial area, a second fan for cooling the other end area different from the first fan, a first shutter for changing the cooling width by the first fan, a second fan Cooling width by fan A second shutter for changing,
A fixing device characterized in that the opening widths of the first shutter and the second shutter are respectively controlled based on the temperature detected by the temperature detecting means at the end portion.   The opening width of each of the first shutter and the second shutter is controlled based on the temperature detected by the temperature detecting means at each end according to the detected temperature difference. Fixing device. A heating member that heats a recording material that carries an unfixed image by supplying power from a power source, a fixing member that contacts the unfixed image of the recording material, and a nip region that is in pressure contact with the heating member through the fixing member. A pressure member that forms and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means provided at the central portion and both ends, respectively, and detected by the temperature detecting means at the central portion. Based on the temperature, the control means for controlling the power supply from the power supply to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the one end based on the temperature detected by the temperature detecting means at the end. A first fan for cooling the partial area, a second fan for cooling the other end area different from the first fan, a first shutter for changing the cooling width by the first fan, a second fan Cooling width by fan A second shutter for changing,
A fixing device characterized in that the opening widths of the first shutter and the second shutter are respectively controlled according to the position of the recording material in the cassette relative to the fixing device.   The fixing device according to claim 3, wherein the image writing start position is changed according to the position of the recording material in the cassette with respect to the fixing device. A heating member that heats a recording material that carries an unfixed image by supplying power from a power source, a fixing member that contacts the unfixed image of the recording material, and a nip region that is in pressure contact with the heating member through the fixing member. A pressure member that forms and rotates, a plurality of temperature detecting means for detecting the temperature of the heating member or the fixing member, and temperature detecting means provided at the central portion and both ends, respectively, and detected by the temperature detecting means at the central portion. Based on the temperature, the control means for controlling the power supply from the power supply to the heating member so as to maintain the temperature of the heating member or the fixing member at a predetermined temperature, and the one end based on the temperature detected by the temperature detecting means at the end. A first fan for cooling the partial area, a second fan for cooling the other end area different from the first fan, a first shutter for changing the cooling width by the first fan, a second fan Cooling width by fan A second shutter for changing,
The opening widths of the first shutter and the second shutter are respectively controlled according to a plurality of Th temperature information abutting on the fixing member at the time of confirming the temperature rise when assembling the fixing device. Fixing device.