Patent Publication Number: US-2017371278-A1

Title: Fixing device and image forming apparatus

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC §119 from Japanese Patent Application No. 2016-125075 filed Jun. 24, 2016. 
     BACKGROUND 
     Technical Field 
     The present invention relates to a fixing device and an image forming apparatus. 
     Related Art 
     In recent years, a laser fixing system has been suggested for image forming apparatuses. 
     SUMMARY 
     According to an aspect of the present invention, there is provided a fixing device including: an optical system that includes a lens serving as a light guiding path and concentrates laser light for image fixing at an interface between the lens and a recording material; a holding part that holds the lens of the optical system; an operating part that rotates together with the holding part; and a suppressing unit that suppresses propagation of energy of the laser light from the holding part to the operating part. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An exemplary embodiment of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a diagram showing an image forming apparatus, to which the exemplary embodiment is applied, when viewed from a front side; 
         FIG. 2  is a diagram illustrating an outline configuration of a fixing device; 
         FIG. 3  is a diagram illustrating an outline configuration of a fixing device, and shows a first configuration example; 
         FIGS. 4A and 4B  are diagrams illustrating configuration examples of periphery of an edge of a transparent rod:  FIG. 4A  shows a second configuration example; and  FIG. 4B  shows a third configuration example; and 
         FIGS. 5A to 5C  are diagrams illustrating configuration examples of periphery of the edge of the transparent rod:  FIG. 5A  shows a fourth configuration example;  FIG. 5B  shows a fifth configuration example; and  FIG. 5C  shows a sixth configuration example. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, an exemplary embodiment according to the present invention will be described in detail with reference to attached drawings. 
       FIG. 1  is a diagram showing an image forming apparatus  100 , to which the exemplary embodiment is applied, when viewed from a front side. 
     The image forming apparatus  100  shown in the figure has a configuration of a so-called tandem type and includes plural image forming units  10  ( 10 Y,  10 M,  10 C and  10 K) for forming toner images of respective color components by the electrophotographic system. Moreover, the image forming apparatus  100  according to the exemplary embodiment is provided with a controller that is configured to include a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory) and others, to thereby control operations of each device and each part constituting the image forming apparatus  100 . 
     The image forming units  10  are an example of an image forming unit. 
     Moreover, the image forming apparatus  100  includes an intermediate transfer belt  20  to which the toner images of the respective color components formed in the respective image forming units  10  are sequentially transferred (primary transfer) and which holds the toner images of the respective color components, and a secondary transfer device  30  that collectively transfers (secondary transfer) the toner images of the respective color components on the intermediate transfer belt  20  onto a recording material P formed in a rectangular shape. The recording material P is a medium on which fixing is performed, such as paper, film, or the like. 
     The intermediate transfer belt  20  and the secondary transfer device  30  are an example of a transfer unit. 
     Moreover, the image forming apparatus  100  is provided with a sheet feeder  40  that feeds the recording material P. Moreover, between the sheet feeder  40  and the secondary transfer device  30 , plural transport rolls  41  for transporting the recording material P positioned on a sheet transport route are provided. 
     Moreover, in the exemplary embodiment, a fixing device  50  that fixes the image having been secondarily transferred onto the recording material P by the secondary transfer device  30  onto the recording material P is provided. Further, between the secondary transfer device  30  and the fixing device  50 , a transport device  42  that transports the recording material P having passed through the secondary transfer device  30  to the fixing device  50  is provided. 
     The fixing device  50  is an example of a fixing unit. 
     Here, each of the image forming units  10  functioning as part of the image forming part includes a photoconductive drum  11  that is rotatably attached. Moreover, around the photoconductive drum  11 , there are provided a charging device  12  that charges the photoconductive drum  11 , an exposure device  13  that exposes the photoconductive drum  11  to write an electrostatic latent image, and a developing device  14  that visualizes the electrostatic latent image on the photoconductive drum  11  with toner. Further, there are provided a primary transfer device  15  that transfers the toner images of the respective color components formed on the photoconductive drum  11  onto the intermediate transfer belt  20 , and a drum cleaner  16  that removes residual toner on the photoconductive drum  11 . 
     The intermediate transfer belt  20  is provided to be disposed on plural roll members  21 ,  22 ,  23 ,  24 ,  25  and  26  to be rotated. Of these roll members  21  to  26 , the roll member  21  is configured to drive the intermediate transfer belt  20 . Moreover, the roll member  25  is provided to face the secondary transfer roll  31  with the intermediate transfer belt  20  being interposed therebetween; accordingly, the secondary transfer device  30  is configured with these secondary transfer roll  31  and roll member  25 . 
     Note that, at a position facing the roll member  21  with the intermediate transfer belt  20  being interposed therebetween, a belt cleaner  27  that removes residual toner on the intermediate transfer belt  20  is provided. 
       FIGS. 2 and 3  are diagrams illustrating outline configurations of the fixing device  50 .  FIG. 2  is a diagram as viewed from an edge side of a transparent rod  51 , and  FIG. 3  is a diagram as viewed from a circumferential surface side of the transparent rod  51 . Moreover,  FIG. 3  shows a first configuration example as an example of a suppressing unit. 
     As shown in  FIG. 2 , in the exemplary embodiment, the fixing device  50  includes a rotatable transparent rod  51  that is configured in a columnar shape with a transparent material capable of transmitting a beam Bm and a facing roll  52  that is provided to face the transparent rod  51  to form a contact area, the facing roll  52  cooperating with the transparent rod  51 , to thereby transport the recording material P. Moreover, the fixing device  50  includes a light concentrator (linear light concentrator)  53  that causes laser light or the beam Bm, which is to be concentrated into a linear region extending over an entire width of a region (narrow light concentration width) of the recording material P onto which an image is transferred, to enter the transparent rod  51 . The transparent rod  51  is an example of a lens. 
     The fixing device  50  is a laser fixing device that directly heats toner on the recording material P by the beam Bm from the light concentrator  53  concentrated in the linear region, to thereby perform melting-fixing. Note that, by narrowing the width of the linear region, light concentration efficiency is improved, and a fixing portion is rapidly cooled. 
     “Transparent” in the transparent rod  51  means high transmittance in a wavelength region of the beam Bm, which just has to transmit the beam Bm, and the higher the transmittance is, the better from a standpoint of light use efficiency or the like. For example, the transmittance may be 90% or more, and desirably, 95% or more. 
     Moreover, the facing roll  52  is configured with, for example, aluminum, stainless steel, a nickel-plated copper plate or others, and is disposed such that a predetermined pressurizing force is applied between the transparent rod  51  and the facing roll  52 . 
     As shown in  FIG. 3 , the light concentrator  53  of the fixing device  50  is configured to include a laser stack  61  that emits beams Bm and an optical system  62  that concentrates the beams Bm from the laser stack  61 . The optical system  62  concentrates the beams Bm to an interface between the transparent rod  51  and the recording material P. To additionally describe, the transparent rod  51  serves as a light guiding path when light concentration is performed by the optical system  62 . 
     Note that the laser stack  61  is used in the exemplary embodiment; however, instead of the laser stack  61 , it is possible to use a vertical cavity surface emitting laser unit, which is an areal light emitting array. 
     Both edges  51   a  of the transparent rod  51  are integrally held by respective holding parts  71 . Moreover, bearings  72  that are positioned away from the edges  51   a  of the transparent rod  51  rotatably hold operating parts  73 . Such operating parts  73  are formed to be connected to the holding parts  71 . A driving force from a not-shown driving source is inputted to the operating part  73  of any one side of the respective edges  51   a  of the transparent rod  51 , and the holding parts  71  and the operating parts  73  are subjected to rotation operation by such a driving force. 
     In this manner, due to rotation operation of the holding parts  71  together with the operating parts  73 , the transparent rod  51  held by the holding parts  71  is rotated in one direction. 
     Note that, as the bearing  72 , it can be considered to use a ball bearing, as well as to use a plastic bearing. 
     As shown in  FIG. 3 , between the edge  51   a  of the transparent rod  51  and the holding part  71 , a heat absorbing part  74  that absorbs heat of light rays from the edge  51   a  of the transparent rod  51  is provided. In other words, the heat absorbing part  74  absorbs heat of the light rays (refer to arrows in the figure) having reached the edge  51   a  of the transparent rod  51  after entering the transparent rod  51  and repeating reflection of part or all thereof inside the transparent rod  51 . 
     Moreover, at the holding part  71 , there is provided a fin  75  that releases the heat absorbed by the holding part  74  to the outside. The fin  75  is configured to include multiple thin plate parts  75   a  and  75   b  extending from the holding part  71  toward the radial direction. 
     In the exemplary embodiment, since transfer of the heat of the light rays at the end portion of the transparent rod  51  from the holding part  71  to the bearing  72  via the operating part  73  is suppressed by the above-described heat absorbing part  74  and the fin  75 , generation of bad effects to fixing performance by heat is prevented. 
     In the first configuration example, the heat absorbing part  74  has a function of absorbing heat of the light rays (heat absorption function), and the fin  75  has a function of suppressing temperature rising due to heat of the light rays (cooling function). The heat absorbing part  74  and the fin  75  are an example of a suppressing unit that suppresses propagation of energy of light rays to the operating part  73 . The fin  75  is an example of an ejection part. 
     Here, various kinds of configuration examples other than the first configuration example in the exemplary embodiment will be described. In other words, other suppressing units formed by configurations other than the heat absorbing part  74  and the fin  75  will be described. 
       FIGS. 4A and 4B  are diagrams illustrating configuration examples of periphery of the edge  51   a  of the transparent rod  51 , and show only the right end portion of the transparent rod  51  in  FIG. 3 .  FIGS. 4A and 4B  show configuration examples different from each other:  FIG. 4A  shows a second configuration example; and  FIG. 4B  shows a third configuration example. 
     In the second configuration example shown in  FIG. 4A , a chiller  76  that is a device for keeping the holding part  71  at a constant temperature is provided. Such a chiller  76  is a heat exchanger (a liquid cooler or a water cooler) that moves the heat of the light rays absorbed by the heat absorbing part  74  to the outside from the holding part  71  by a fluid. In other words, the chiller  76  is configured to include an inlet and an outlet of the fluid formed at the end portion of the operating part  73  and a flow path through which the fluid flows in one direction from the inlet to the outlet within the holding part  71  and the operating part  73 . Note that, by adopting a flow path such that an inlet is formed on the center of a cross section of the holding part  71  and an outlet is formed on a peripheral side thereof, the fluid flows smoothly by using a centrifugal force in the rotation of the holding part  71 . 
     In the second configuration example, the heat absorbing part  74  has the heat absorption function, and the chiller  76  has the cooling function. The heat absorbing part  74  and the chiller  76  are an example of the suppressing unit. The chiller  76  is an example of the ejection part. 
     Moreover, in the third configuration example shown in  FIG. 4B , a heat dissipating part  77  that dissipates heat of the holding part  71  and an air blowing part  78  that blows air toward the heat dissipating part  77  are provided. Such a heat dissipating part  77  is configured to improve heat dissipating property by forming recessed portions on an outer surface of the holding part  71  and increasing a surface area, and the heat dissipating part  77  can also be referred to as an air cooler. The heat dissipating part  77  of the holding part  71  dissipates the heat of the light rays absorbed by the heat absorbing part  74  into the air by the wind from the air blowing part  78 . Moreover, since the fixing device  50  is rotated when being operated, the heat can easily be dissipated into the air by adding an air cooling function on the surface of such a holding part  71  that is rotated and operated. In this manner, the heat of the heat absorbing part  74  is less likely to be transferred to the operating part  73  from the holding part  71 . Note that a modified example in which the air blowing part  78  is omitted can be considered. 
     In the third configuration example, the heat absorbing part  74  has the heat absorbing function, and the heat dissipating part  77  and the air blowing part  78  have the cooling function. The heat absorbing part  74  and the heat dissipating part  77  are an example of the suppressing unit, and the heat dissipating part  77  is an example of the ejection part. 
       FIGS. 5A to 5C  are diagrams illustrating configuration examples of periphery of the edge  51   a  of the transparent rod  51 , and correspond to  FIGS. 4A and 4B .  FIGS. 5A to 5C  show configuration examples different from one another:  FIG. 5A  shows a fourth configuration example;  FIG. 5B  shows a fifth configuration example; and  FIG. 5C  shows a sixth configuration example. 
     In the fourth configuration example shown in  FIG. 5A , a reflective film  81  that reflects the light rays is formed between the transparent rod  51  and the holding part  71 . Such a reflective film  81  is formed by, for example, a reflective coating. The reflective film  81  reflects the light rays reaching from the center of the transparent rod  51  to the edge  51   a  toward the center. The heat of the light rays reflected like this is removed from the inside of the transparent rod  51  by, for example, being used for fixing onto the recording material P. Note that, in the fourth configuration example, the heat absorbing part  74  (refer to  FIG. 3  or  FIGS. 4A and 4B ), which is included in the above-described first to third configuration examples, is not provided. 
     In the fourth configuration example, the reflective film  81  has a function of reflecting the light rays (reflection function). The reflective film  81  is an example of the suppressing unit, and an example of the reflection part. 
     In the fifth configuration example shown in  FIG. 5B  and the sixth configuration example shown in  FIG. 5C , reflective mirrors  51   b  and  51   c  that reflect the light rays are formed at the portion (end portion) of the transparent rod  51  corresponding to the holding part  71 , respectively. Each of the reflective mirrors  51   b  and  51   c  is configured to include vapor-deposited metal coating and dielectric multi-layer. 
     The reflective mirror  51   b  in the fifth configuration example shown in  FIG. 5B  is a retroreflector or a corner cube, and the reflective mirror  51   c  in the sixth configuration example shown in  FIG. 5C  is multiple retroreflectors. 
     In the fifth configuration example and the sixth configuration example, the reflective mirrors  51   b  and  51   c  have the reflection function. The reflective mirrors  51   b  and  51   c  are an example of the suppressing unit, and an example of the reflection part. 
     The foregoing description of the present exemplary embodiment of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The present exemplary embodiment was chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.