Patent Publication Number: US-2022236677-A1

Title: Fixing device and image forming apparatus

Description:
INCORPORATION BY REFERENCE 
     This application claims priority on the basis of Japanese Application No. 2021-011176, filed Jan. 27, 2021, and incorporates the contents of said application. 
     BACKGROUND 
     The present disclosure relates to a fixing device and an image forming apparatus. 
     In general, an image forming apparatus includes a fixing device for fixing a toner image to a recording medium. The fixing device includes a heating roller and a pressure roller. The heating roller has a rotating member, a heating member, and a support member. The heating member is arranged in the rotating member, a metal terminal connected to the end of the heating member is fixed to a nut by a screw, and the nut is inserted into a guide groove formed in the support member. Since the nut can move in the longitudinal direction of the rotating member, the influence of thermal expansion of each part is reduced. 
     In the conventional image forming apparatus, when the nut receives a rotational force in the guide groove, the movement of the nut is inhibited. As a result, there was a possibility of damaging the heating member due to thermal expansion. 
     SUMMARY 
     A fixing device according to the present disclosure includes a heating roller and a pressure roller. The heating roller heats the recording medium on which the toner image is formed. The pressure roller pressurizes the recording medium with the heating roller. The heating roller has a rotating member, a heating member, and a support member. The rotating member has a hollow part and rotates around a rotary shaft along the longitudinal direction. The heating member generates heat in a state of being inserted into the hollow part. The support member supports the rotating member and the heating member. The heating member has a heater, a first terminal, and a second terminal. The heater generates heat by energization. The first terminal is connected to one end of the heater. The second terminal is connected to the other end of the heater. The first terminal protrudes from one end of the rotating member in the longitudinal direction and is hooked on a hook provided on the support member so as to be movable along the longitudinal direction. The second terminal protrudes from the other end of the rotating member in the longitudinal direction and is fixed to the support member so as not to be movable along the longitudinal direction. 
     The image forming apparatus of the present disclosure includes the fixing device and the image forming section. The image forming section forms the toner image on the recording medium. The fixing device fixes the toner image on the recording medium. 
     The purpose, features, and advantages of the present disclosure are further illustrated by the detailed description below. The detailed description refers to the accompanying drawings, which show preferred embodiments of the present disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE INVENTION 
         FIG. 1  is a schematic diagram showing an example of the structure of an image forming apparatus according to an embodiment. 
         FIG. 2  is an exploded perspective view showing the entire structure of a heating roller constituting a part of the fixing device. 
         FIG. 3  is a perspective view showing the overall configuration of the heating roller. 
         FIG. 4  is an exploded perspective view showing an end configuration of the heating roller on the first terminal side. 
         FIG. 5  is a perspective view showing the end configuration of the heating roller on the first terminal side. 
         FIG. 6  is an exploded perspective view showing the configuration of the second terminal side end of the heating roller. 
         FIG. 7  is a perspective view showing the configuration of the second terminal side end of the heating roller. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure will be described with reference to the drawings. In the drawings, the same or corresponding portions are denoted by the same reference numerals and the description is not repeated. 
     An image forming apparatus  100  according to an embodiment will be described with reference to  FIG. 1 .  FIG. 1  is a schematic diagram showing an example of the configuration of the image forming apparatus  100 . The image forming apparatus  100  is, for example, a printer. 
     As shown in  FIG. 1 , the image forming apparatus  100  includes a paper feed cassette  11 , a paper feed roller  12 , a conveyance path  13 , a plurality of conveyance rollers  13   a,  a transfer roller  14 , a discharge roller  16 , a discharging section  17 , an image forming section  20 , and a fixing device  30 . Each of the plurality of conveyance rollers  13   a  is provided in the conveyance path  13 . 
     The paper feed cassette  11  can store a plurality of recording media P (for example, printing paper). The paper feed roller  12  feeds the recording medium P in the paper feed cassette  11  one by one to the conveyance path  13 . The conveyance roller  13   a  conveys the recording medium P fed to the conveyance path  13  toward the image forming section  20 . 
     An image forming section  20  forms a toner image on a recording medium P. The image forming section  20  includes a photosensitive drum  21 , a toner container  22 , a developing device  23 , a charging device  24 , an exposure device  25 , and a cleaning device  26 . 
     The charging device  24  uniformly charges the photosensitive drum  21  to a predetermined polarity by discharge. The exposure device  25  irradiates the charged photosensitive drum  21  with a laser beam. Thus, an electrostatic latent image is formed on the surface of the photosensitive drum  21 . 
     The developing device  23  develops an electrostatic latent image formed on the surface of the photosensitive drum  21  to form a toner image. The toner container  22  supplies toner to the developing device  23 . The developing device  23  supplies the toner replenished from the toner container  22  to the surface of the photosensitive drum  21 . As a result, a toner image is formed on the surface of the photosensitive drum  21 . 
     The transfer roller  14  transfers the toner image formed on the surface of the photosensitive drum  21  to the recording medium P. The recording medium P on which the toner image is transferred is conveyed toward the fixing device  30 . The cleaning device  26  cleans the residual toner on the surface of the photosensitive drum  21 . 
     The fixing device  30  fixes the toner image on the recording medium P. The fixing device  30  includes a heating roller  31  and a pressure roller  32 . The heating roller  31  and the pressure roller  32  are arranged to face each other to form a fixing nip. The heating roller  31  heats the recording medium P on which the toner image is formed. The pressure roller  32  pressurizes the recording medium P with the heating roller  31 . The recording medium P is pressurized while being heated at a predetermined fixing temperature by passing through the fixing nip. As a result, the toner image is fixed to the recording medium P. 
     The recording medium P on which the toner image has been fixed is conveyed from the fixing device  30  toward the discharging section  17  by the conveyance roller  13   a  and the discharge roller  16 . 
     Next, referring to  FIGS. 2 and 3 , a description will be given of a heating roller  31  constituting a part of the fixing device  30 .  FIG. 2  is an exploded perspective view showing the overall configuration of the heating roller  31 .  FIG. 3  is a perspective view showing the overall configuration of the heating roller  31 . 
     As shown in  FIGS. 2 and 3 , the heating roller  31  includes a rotating member  50 , a heating member  40 , and a support member  60 . The rotating member  50  has a hollow part and rotates around a rotary shaft along the longitudinal direction D. The heating member  40  generates heat while being inserted into the hollow portion of the rotating member  50 . The support member  60  supports the rotating member  50  and the heating member  40 . The support member  60  is made of synthetic resin, for example. 
     The heating member  40  has a heater  41 , a first terminal  42 , and a second terminal  43 . The heater  41  generates heat by energization. The heater  41  is, for example, a halogen heater. The first terminal  42  is a metal terminal connected to one end of the heater  41 . The first terminal  42  has a shape in which two rectangular plates of different sizes are connected to each other, and has a hole  42   a  penetrating in the thickness direction. The second terminal  43  is a metal terminal connected to the other end of the heater  41 . The second terminal  43  has the same shape as the first terminal  42  and has a hole  43   a  penetrating in the thickness direction. 
     The heater  41  extends along the longitudinal direction D of the rotating member  50 . As shown in  FIG. 3 , the first terminal  42  protrudes from one end of the rotating member  50  in the longitudinal direction D and is hooked on the first hook  61  and the second hook  62  provided on the support member  60  so as to be movable along the longitudinal direction D. The second terminal  43  protrudes from the other end of the rotating member  50  in the longitudinal direction D and is fixed to the support member  60  so as not to be movable along the longitudinal direction D. 
     The rotating member  50  has a body portion  51 , a first bush  52 , and a second bush  53 . The body portion  51  is a tubular body having an outer peripheral surface. The body portion  51  is made of a conductive material such as aluminum. A mold release layer is formed in the central portion of the outer peripheral surface of the body portion  51 . As shown in  FIG. 3 , the sheet passing region R, which indicates the region through which the recording medium P passes, is included in the region where the mold release layer is formed. The first bush  52  is fitted in the outer peripheral surface of the body portion  51  on the side of the first terminal  42  in the longitudinal direction D. The first bush  52  constitutes a part of the first sliding bearing. The second bush  53  is fitted in the outer peripheral surface of the body portion  51  on the side of the second terminal  43  in the longitudinal direction D. The second bush  53  constitutes a part of the second sliding bearing. The first bush  52  is non-conductive and the second bush  53  is conductive. The first bush  52  may have insulating properties. 
     The heating roller  31  further includes a temperature sensor  90  for detecting the surface temperature of the heating roller  31 . The temperature sensor  90  is, for example, a thermistor. The temperature sensor  90  is fixed to the support member  60  in the vicinity of the second terminal  43  outside the sheet passing region R. 
     Next, with reference to  FIGS. 4 and 5 , the end configuration of the heating roller  31  on the side of the first terminal  42  will be described in detail.  FIG. 4  is an exploded perspective view showing the end structure of the heating roller  31  on the side of the first terminal  42 .  FIG. 5  is a perspective view showing an end configuration of the heating roller  31  on the side of the first terminal  42 . 
     As shown in  FIGS. 4 and 5 , the support member  60  has a first flat plate part  63  in addition to the first hook  61  and the second hook  62 . The first hook  61  extends along a direction intersecting the longitudinal direction D from the first flat plate part  63 , and extends parallel to the first flat plate part  63  and away from the first bush  52 . The second hook  62  also extends along a direction intersecting the longitudinal direction D from the first flat plate part  63  and extends parallel to the first flat plate part  63  and away from the first bush  52 . The first terminal  42  is hooked on the first hook  61  and the second hook  62  while being placed on the first flat plate part  63 . As a result, the first terminal  42  is sandwiched between the first flat plate part  63 , the first hook  61  and the second hook  62 , and can move along the longitudinal direction D. The hole  42   a  of the first terminal  42  is not used. 
     Next, with reference to  FIGS. 6 and 7 , the end configuration of the heating roller  31  on the side of the second terminal  43  will be described in detail.  FIG. 6  is an exploded perspective view showing an end configuration of the heating roller  31  on the side of the second terminal  43 .  FIG. 7  is a perspective view showing an end configuration of the heating roller  31  on the side of the second terminal  43 . 
     As shown in  FIG. 6 , the support member  60  includes a first rib  71 , a second rib  72 , a third rib  73 , a second flat plate part  74 , and a recessed portion  75 . The second terminal  43  is placed on the second flat plate part  74 , and is fixed by a nut  81  and a screw  82  in a state where movement along the longitudinal direction D is restricted by the first rib  71 , the second rib  72  and the third rib  73 . More specifically, the nut  81  is inserted into the recessed portion  75  formed adjacent to the second flat plate part  74 , and the screw  82  is inserted into the hole  43   a  of the second terminal  43 . The second terminal  43  is fixed by tightly screwing the nut  81  and the screw  82 . 
     According to the embodiment, since the first terminal  42  can move along the longitudinal direction D, there are provided a fixing device  30  and an image forming apparatus  100  capable of substantially mitigating the influence of thermal expansion. 
     Moreover, according to the embodiment, since the first bush  52  is non-conductive or insulating, the spark failure of the heater  41  can be suppressed even if the first hook  61  and the second hook  62  are damaged. 
     According to the embodiment, the temperature sensor  90  is fixed near the second terminal  43 . Therefore, the positional accuracy of the temperature sensor  90  relative to the heater  41  in the longitudinal direction D is relatively high as compared with the case where the temperature sensor  90  is fixed in the vicinity of the first terminal  42 , and high-precision temperature control of the heating roller  31  is achieved. 
     Embodiments of the present disclosure have been described with reference to the drawings. However, the present disclosure is not limited to the embodiments described above, and may be implemented in various aspects without departing from the spirit thereof. Various embodiments can be formed by suitably combining the plurality of components disclosed in the above embodiments. For example, some components may be removed from all components shown in the embodiment. The drawings schematically show the respective components for the sake of easy understanding, and the number of the illustrated components may differ from the actual number due to the convenience of drawing preparation. Each of the components shown in the above embodiment is an example, and is not particularly limited, and various changes can be made without substantially departing from the effect of the present invention. 
     Although the image forming apparatus  100  is a printer in the embodiment, the present invention is not limited thereto. The image forming apparatus  100  may be, for example, a composite machine having a function of a copying machine, a printer, and a facsimile. 
     The present disclosure is applicable to the field of fixing devices and image forming apparatuses.