JP2017021173A - Heating fixation device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress temperature rise of a non-sheet passage part due to longitudinal temperature distribution control of a halogen lamp being heating means of a fixation member.SOLUTION: A fixation device comprises: an endless fixation belt which travels in a prescribed direction, melts a toner image by heating it, and has flexibility; a fixation member which is fixedly arranged on the inner peripheral surface side of a fixation film and is brought into pressure contact with a pressure rotor via the fixation belt to form a nip part to which a recording medium is conveyed; a heater which is fixedly arranged so as to face the inner peripheral surface of the fixation film at a position excluding the nip part and heats the fixation belt; a reflection member which faces the heater and reflects the light emitted from the heater toward the inner peripheral surface of the fixation film; and an angle variation member which changes the angles of both end regions of the reflection member. The angle variation member changes the angles of the prescribed longitudinal both end regions of the reflection member in accordance with longitudinal end temperature rise information of the fixation film.SELECTED DRAWING: Figure 3

Description

  The present invention relates to an electrophotographic heating and fixing apparatus capable of forming an image on a recording material such as a multifunction peripheral, a copying machine, a printer, and a fax machine, and an image forming apparatus.

  Conventionally, in an image forming apparatus such as a copying machine or a printer, a fixing member is slidably contacted with an inner peripheral surface of an endless belt member, and the fixing member is pressed against a rotating body via the belt member. A fixing device that forms a nip portion with a rotating body, conveys a recording medium to the nip portion, and fixes a toner image on the recording medium is widely used (see Patent Documents 1 to 3).

  Patent Documents 1 and 2 disclose an on-demand fixing device with a short warm-up time. An on-demand fixing device includes a fixing film (endless film) as a belt member, a pressure roller as a rotating body, a heater as a fixed member, and the like. The heater is installed inside the fixing film, presses the pressure roller through the fixing film to form a nip portion, and heats the fixing film at the position of the nip portion. The toner image on the recording medium conveyed toward the nip portion is fixed on the recording medium by receiving heat and pressure at the nip portion.

  Patent Document 3 discloses a fixing device using a fixing belt (endless belt) in which a heating unit (halogen lamp) is provided as a fixing member and using a pressure roller. Specifically, a pressure pad (pressure pad) as a fixing member is fixed so as to be in sliding contact with the inner peripheral surface of the fixing belt while being urged toward the nip portion by a spring. As a result, the pressure pad is pressed against the pressure roller via the pressure belt to form a nip portion. The toner image on the recording medium conveyed toward the nip portion is fixed on the recording medium by receiving heat and pressure at the nip portion.

  Here, Patent Document 3 discloses a technique in which a heat amount adjusting member is disposed between a halogen heater and a fixing belt, and the amount of radiant heat supplied from the heater to the fixing belt is changed depending on the size of the recording medium. This is because when a recording medium (small size paper) having a paper passing width smaller than the maximum paper passing width that can be introduced and used in the fixing device is continuously fed and heat fixing is performed, Heat consumed by the recording material in the pressure roller is compensated by the temperature control system and maintained at a predetermined temperature, whereas heat is consumed by heating the recording material in the non-sheet passing portion. This is used in order to suppress the non-sheet-passing portion temperature rise problem in which the temperature of the non-sheet-passing portion is not stored and the temperature of the non-sheet-passing portion is higher than that of the sheet-passing portion that is maintained at a predetermined temperature.

JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP 2010-032973 A

  In the technique described in Patent Document 3, the temperature rise of the non-sheet passing portion by the longitudinal temperature distribution control of the halogen lamp which is a heating means of the fixing member is a problem.

The heat fixing device according to the present invention is:
The toner image travels in a predetermined direction to melt by heating, and is fixed to an endless fixing belt having flexibility and an inner peripheral surface side of the fixing film, and is pressed through the fixing belt. A fixing member that forms a nip portion where the recording medium is conveyed by being pressed against the rotating body, and a fixing member that is fixed to face the inner peripheral surface of the fixing film at a position excluding the nip portion, and heats the fixing belt. A reflective member that reflects the light emitted from the heater facing the heater toward the inner peripheral surface of the fixing film;
In the fixing device having an angle variable member that changes the angle of the both end regions of the reflection member, the angle variable member corresponds to the predetermined longitudinal end region of the reflection member according to the temperature increase information of the longitudinal end portion of the fixing film. It is characterized by changing the angle.
The reflecting member is composed of three regions, an end region and a central region, and the angle of the connecting portion is variable.
The movement of the variable angle member is driven by a DC motor.

  According to the heat fixing device of the present invention, it is possible to control the longitudinal region of the radiation from the halogen heater that is transmitted to the fixing belt with a simple configuration.

Schematic diagram of the image forming apparatus in the first embodiment Schematic diagram of the fixing device in the first embodiment Sectional view of the fixing device in the first embodiment Operation flow diagram of the first embodiment Conceptual diagram of variable angle θ in the first embodiment Longitudinal surface temperature distribution diagram of fixing belt in the first embodiment

  Next, specific examples (examples) of the embodiments of the present invention will be described with reference to the drawings, but the present invention is not limited to the following examples.

  FIG. 1 is a cross-sectional view of a color electrophotographic printer which is an example of an image forming apparatus according to the present embodiment, and is a cross-sectional view along a sheet conveyance direction. In this embodiment, the color electrophotographic printer is simply referred to as “printer”.

  The printer shown in FIG. 1 includes an image forming unit 10 for each color of Y (yellow), M (magenta), C (cyan), and Bk (black). The photosensitive drum 11 is charged in advance by a charger 12. Thereafter, a latent image is formed on the photosensitive drum 11 by the laser scanner 13. The latent image becomes a toner image by the developing device 14. The toner image on the photosensitive drum 11 is sequentially transferred by the primary transfer blade 17 to, for example, an intermediate transfer belt 31 that is an image carrier. After the transfer, the toner remaining on the photosensitive drum 11 is removed by the cleaner 15. As a result, the surface of the photosensitive drum 11 becomes clean and prepares for the next image formation.

  On the other hand, the sheets P are sent one by one from the paper feed cassette 20 or the multi paper feed tray 25 and sent to the registration roller pair 23. The registration roller pair 23 receives the sheet P once, and straightens it when the sheet is skewed. The registration roller pair 23 feeds the sheet between the intermediate transfer belt 31 and the secondary transfer roller 35 in synchronization with the toner image on the intermediate transfer belt 31. The color toner image on the intermediate transfer belt is transferred onto the sheet P by, for example, a secondary transfer roller 35 which is a transfer body. Thereafter, the toner image on the sheet is fixed to the sheet by the sheet being heated and pressed by the fixing device 40.

  Next, the fixing device used in this embodiment will be described. FIG. 2 uses a belt heating type heating device (tensionless type) as shown in the schematic configuration diagram of the fixing device 40.

Reference numeral 43 denotes a halogen heater or carbon heater (hereinafter referred to as a heater) as a heating body, and both ends thereof are fixed to the side plate of the fixing device 40. Then, the radiant heat of the heater 43 whose output is controlled by the power supply unit of the apparatus main body is reflected by the reflecting plate 42 to reach the fixing belt 41 and the fixing belt 41 is heated.
Reference numeral 41 denotes a cylindrical (endless) heat-resistant fixing belt as a heating member for transmitting heat, and is loosely fitted on a support member including the heater 43 described above. The fixing belt 41 in this embodiment is a fixing belt having a four-layer composite structure of a surface layer, an elastic layer, a base layer, and an inner surface coating layer.

  As the release layer, a fluororesin material having a thickness of 100 μm or less, preferably 20 to 70 μm can be used. For example, examples of the fluororesin layer include PTFE, FEP, PFA, and the like. In this example, a PFA tube having a thickness of 30 μm was used.

  The elastic layer can be made of a rubber material having a thickness of 1000 μm or less, preferably 500 μm or less in order to reduce the heat capacity and improve the quick start. For example, silicone rubber, fluorine rubber and the like can be mentioned. Silicone rubber having a rubber hardness of 10 degrees (JIS-A), a thermal conductivity of 1.3 W / m · K, and a thickness of 300 μm was used.

  Similarly to the elastic layer, the base metal layer can be made of a heat-resistant material having a thickness of 100 μm or less, preferably 50 μm or less and 20 μm or more in order to improve the quick start property. For example, a metal film such as SUS or nickel can be used.

  In this example, a cylindrical nickel metal film having a thickness of 30 μm and a diameter of 25 mm was used.

  Since the inner surface coating layer is in contact with the pressure pad, a heat-resistant resin layer, ceramics, metal, or the like can be used. For example, polyimide, polyimide amide, PEEK, polytetrafluoroethylene resin (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer resin (FEP), tetrafluoroethylene / perfluoroalkyl vinyl ether copolymer resin ( Engineering plastics such as PFA) and diamond-like carbon (DLC).

  Reference numeral 44 denotes a heat-resistant elastic pressure roller as a pressure member, which is composed of a cored bar and an elastic layer made of a heat-resistant rubber such as silicone rubber or fluorine rubber, or a foam of silicone rubber, and rotates both ends of the cored bar. The bearing is supported freely. The fixing belt 41 and the heater 43 are arranged on the upper side of the pressure roller 44 in parallel with the pressure roller 44 with respect to the heater 43 side, and are pressed by a pressing member (not shown). Then, a fixing nip T having a predetermined width as a heating portion is formed by pressing the lower surface of the heater 43 and the upper surface of the pressure roller 44 against the elasticity of the roller elastic layer.

  The pressure roller 44 is rotationally driven by a driving means (not shown) in the counterclockwise direction indicated by an arrow at a predetermined rotational peripheral speed. A rotational force acts on the cylindrical fixing belt 41 by the pressure friction force at the fixing nip portion T between the pressure roller 44 and the fixing belt 41 by the rotation driving of the pressure roller 44, and the fixing belt 41 is pressed against the pressure pad. 46 is in a state of being driven to rotate in the clockwise direction of the arrow while sliding in close contact with the downward surface of 46. The support member is also a rotation guide member for the cylindrical fixing belt 41.

  45a and 45b are contact-type thermometers (thermistors) that measure the temperature of the fixing belt 41 heated by the heater 43 and pass the detection result to a temperature control means (not shown). 45a is arranged at the center of the fixing belt 41 and detects the temperature of the sheet passing area of the recording material P. Further, 45b is arranged at the end of the fixing belt 41 and detects the temperature of the non-sheet passing area of the recording material P.

  Reference numeral 46 denotes a pressure pad, which is a member that forms a nip portion in pressure contact with the pressure roller.

  When the pressure roller 44 is driven to rotate, the cylindrical fixing belt 41 is driven and rotated, and the heater 43 is energized to raise the temperature of the fixing belt 41 and rise to a predetermined temperature. , The recording material P carrying the unfixed toner image T is introduced between the fixing belt 41 and the pressure roller 44 in the fixing nip T, and the toner image carrying side surface of the recording material P is fixed in the fixing nip N. The fixing nip portion T is nipped and conveyed together with the fixing belt 41 in close contact with the outer surface of the belt 41. In this nipping and conveying process, the recording material P is heated by the heat of the fixing belt 41 heated by the heater 43, and the unfixed toner image T on the recording material P is heated and pressurized on the recording material P to be melted and fixed. . The recording material P that has passed through the fixing nip T is separated from the surface of the fixing belt 41 and is discharged and conveyed.

[Reflection member]
First, details of the reflecting member 42 in the configuration of the present embodiment will be described. As shown in FIG. 3, the reflecting plate 42 has a three-part configuration of a central part 42a and both end parts 42b with respect to the longitudinal direction. It is provided at both ends of the fixing member (outside the longitudinal area of the fixing belt). The variable angle mechanism 47 uses a DC motor as a drive source, and both end portions 42b of the reflecting plate move at a predetermined angle θ with respect to the longitudinal direction by the displacement of the variable angle mechanism 47. This prevents radiation from the heater facing the opposite end portions 42 b of the reflector from being transmitted to the end portions of the fixing belt 41.

  At the same time, by collecting the radiation in the longitudinal central region (sheet passing region), the heat generation efficiency of the sheet passing region can be increased.

  A specific example of this embodiment will be described with reference to FIG. As operating conditions, the pressure condition was 30 kgf in total pressure, the rotation speed of the fixing belt and the pressure roller was 250 mm / s, and the input power to the heater was 800 W.

  First, when the sheet passing size of the output recording medium is input, as shown in Table 1, the non-sheet passing portion region L with respect to the longitudinal length of the fixing belt 41 is determined. Next, the variable angle θ of the both end portions 42b of the reflector is determined so that the heating area of the non-sheet passing area L becomes the sheet passing area of the recording medium. At this time, as shown in FIG. 5, the variable angle θ and the movement distance 1 in the longitudinal direction of the radiant heat can be expressed by a relational circle 1.

  In the DC motor used in the present embodiment, the minimum distance lmin of the longitudinal movement distance l is 0.5 mm.

  The variable angle portion of the reflecting plate is arranged according to the end of the minimum recording paper size. In this experiment, the recording paper size to be used is A4R, and the distance d from the reflecting plate 42 to the fixing belt 41 is 20 mm. Will be explained.

  As shown in Table 1, when the recording paper size to be used is A4R, the length of the non-sheet passing portion region L is 26.5 mm. At this time, as shown in FIG. 5, the variable angle θ of the reflector is selected from the relational circle 1 so that the longitudinal movement distance l of the radiant heat becomes 26.5 mm.

  Then, the displacement amount of the angle variable mechanism 47 is determined by the determined variable angle θ, and the fixing operation is started. Further, after the fixing is started, the inner surface temperature of the fixing belt 41 is detected by the contact thermometer 45b. When the inner surface temperature of the fixing belt 41 is equal to or higher than a predetermined temperature, the heater is turned off and the longitudinal movement distance l is set. Is further provided with control means for moving the sheet to the sheet passing area by 2 mm.

[Comparison with conventional technology]
For comparison, Table 2 and FIG. 6 show the results when the present embodiment is not applied and when the variable angles θ = 10 ° and 20 °. First, as shown in Table 2, by applying this example, the surface temperature of the fixing belt 41 in the non-sheet-passing area is reduced by 26 ° at the maximum as compared with the case of the conventional example (not implemented). It was. Further, by moving the radiation that should have been transmitted to the non-sheet passing area to the sheet passing area, the surface temperature of the fixing belt 41 in the sheet passing area is increased by 9 ° at the maximum.
The longitudinal temperature distribution of the above result is shown in FIG. Also in FIG. 6, by applying this example, it was possible to show an effect of suppressing the temperature rise of the non-sheet passing portion as compared with the case of the conventional example (not implemented), and at the same time, the heating efficiency of the sheet passing area was improved. The improvement effect could be shown.

10 image forming unit, 11 photosensitive drum, 12 charger, 13 laser scanner,
14 developing unit, 15 cleaner, 17 primary transfer blade, 20 paper feed cassette,
25 Multi-feed tray, 23 Registration roller pair, 31 Intermediate transfer belt,
35 Secondary transfer roller, 40 fixing device, 41 fixing belt, 42 reflector,
43 heated body, 44 pressure roller, 45a contact thermistor (longitudinal center),
45b contact thermistor (longitudinal end), 46 pressure pad, 47 variable angle mechanism,
48 drive means, 49 control means, 50 tension roller, 51 drive roller,
52 fixing belt, 53 pressure roller, 54 fixing belt pressure member,
55 Halogen heater, 90 pulling motor, 91 heating plate member, P sheet,
T Toner

Claims (3)

The toner image is heated and melted by traveling in a predetermined direction, and is fixed to the endless fixing belt (41) having flexibility and the inner peripheral surface side of the fixing belt (41). A pressing member (46) that forms a nip portion in contact with the pressure rotator (44) via the belt (41) to convey the recording medium;
A heater (42) fixed to be opposed to the inner peripheral surface of the fixing film at a position excluding the nip portion and heating the fixing belt;
A reflecting member (42) that reflects radiation emitted from the heater (42) facing the heater (43) toward the inner peripheral surface of the fixing belt (41);
A fixing device having an angle variable member (47) for changing an angle of both end regions (42b) of the reflecting member (42);
Heating characterized in that the angle variable member (47) changes the angle of a predetermined longitudinal end region (42b) of the reflecting member (42) in accordance with the temperature rise information of the longitudinal end of the fixing belt (41). Fixing device. The said reflection member (42) is comprised from three area | regions, an edge part area | region (42b) and a center area | region (42a), The angle of this connection part is variable, The said 1st aspect is characterized by the above-mentioned. Heat fixing device. The heat fixing device according to claim 1, wherein the angle variable member (47) is driven by a DC motor.