Patent Publication Number: US-7898559-B2

Title: Image forming apparatus

Description:
BACKGROUND 
     1. Technical Field 
     This invention generally relates to image forming apparatuses such as digital copying machines with electrophotographic systems, laser printers, and the like. 
     2. Related Art 
     In image forming apparatuses that employ electrophotographic systems, in general, a light emitted from an optical scanning device composed of: a light source such as a semiconductor laser; and various optical parts is exposed to a photosensitive drum serving as an image holding body uniformly charged to form a latent image. Then, the latent image is developed with toner. Such developed toner image is transferred to a recording medium. 
     In the above-described image forming apparatus, when the toner or dusts are adhered to various optical parts included in the optical scanning device, high image quality cannot be maintained. For this reason, there is known a configuration in which the optical parts included in the optical scanning device are accommodated in a hermetically sealed chassis and the photosensitive drum is exposed to a light through a seal glass (light transmitting portion) arranged at the chassis. There is known another configuration in which the seal glass is provided at a chassis of an optical scanning unit is provided with a cleaning mechanism that removes the toner or ducts adhered to the surface of the seal glass. In the above-described cleaning mechanism, the surface of the seal glass is cleaned by sliding a pad provided at an end of a cleaning rod, when the cleaning rod is inserted or pulled out. 
     SUMMARY 
     According to an aspect of the present invention, an image forming apparatus comprises an optical scanning unit having a light transmitting portion, a cleaning mechanism including: a cleaning rod with a pad at an end portion thereof to be capable of cleaning a surface of the light transmitting portion by sliding on the light transmitting portion; and a retaining mechanism that retains the cleaning rod slidably in a longitudinal direction of the light transmitting portion, and that retains the pad positioned above the optical scanning unit and spaced apart from the optical scanning unit in a state where the cleaning rod is at an insertion completed position. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  shows an example of a schematic configuration of the image forming apparatus according to an aspect of the present invention; 
         FIG. 2  is an external perspective view of an optical scanning unit according to an aspect of the present invention; 
         FIG. 3  is an external perspective view of a cleaning mechanism according to an aspect of the present invention; 
         FIG. 4  is a plan view of the cleaning mechanism according to an aspect of the present invention; 
         FIG. 5  is a cross-sectional view taken along the line A-A in  FIG. 4 ; 
         FIG. 6  is an external perspective view of guide rails according to an aspect of the present invention; 
         FIG. 7  is an external perspective view of the guide rails as viewed from the bottom surface thereof; 
         FIG. 8  is a side view of a guide rail; 
         FIG. 9  is a plan view of the guide rails; 
         FIG. 10A  is a perspective view of a spring member according to an aspect of the present invention; 
         FIG. 10B  is a plan view of the spring member according to an aspect of the present invention; 
         FIG. 11A  is an external perspective view of a guiding member according to an aspect of the present invention; 
         FIG. 11B  is a cross-sectional view of the guiding member according to an aspect of the present invention; 
         FIG. 12A  and  FIG. 12B  are external perspective views as viewed from different directions according to an aspect of the present invention; 
         FIG. 13A  and  FIG. 13B  are enlarged perspective views of a front end portion of the cleaning rod as viewed from different directions according to an aspect of the present invention; 
         FIG. 14A  and  FIG. 14B  are enlarged perspective views of the rear end portion of the cleaning rod as viewed from different directions according to an aspect of the present invention; 
         FIG. 15  is an external perspective view of a pad according to an aspect of the present invention; 
         FIG. 16A  and  FIG. 16B  are cross-sectional views showing an operation of the cleaning mechanism at the time of inserting the cleaning rod; 
         FIG. 17A  and  FIG. 17B  are cross-sectional views showing the operation of the cleaning mechanism subsequent to  FIG. 16B ; 
         FIG. 18A  and  FIG. 18B  are cross-sectional views showing the operation of the cleaning mechanism subsequent to  FIG. 17B ; 
         FIG. 19A  and  FIG. 19B  are cross-sectional views showing the operation of the cleaning mechanism at the time of pulling the cleaning rod; and 
         FIG. 20A  and  FIG. 20B  are cross-sectional views showing the operation of the cleaning mechanism subsequent to  FIG. 19B . 
     
    
    
     DETAILED DESCRIPTION 
     A description will now be given, with reference to the accompanying drawings, of exemplary embodiments of the present invention. 
       FIG. 1  through  FIG. 15  show an image forming apparatus according to aspects of the present invention.  FIG. 1  shows an example of a schematic configuration of the image forming apparatus according to an aspect of the present invention.  FIG. 2  is an external perspective view of an optical scanning unit according to an aspect of the present invention.  FIG. 3  is an external perspective view of a cleaning mechanism according to an aspect of the present invention.  FIG. 4  is a plan view of the cleaning mechanism according to an aspect of the present invention.  FIG. 5  is a cross-sectional view taken along the line A-A in  FIG. 4 .  FIG. 6  is an external perspective view of guide rails according to an aspect of the present invention.  FIG. 7  is an external perspective view of the guide rails as viewed from the bottom surface thereof.  FIG. 8  is a side view of a guide rail.  FIG. 9  is a plan view of the guide rails.  FIG. 10A  is a perspective view of a spring member according to an aspect of the present invention.  FIG. 10B  is a plan view of the spring member according to an aspect of the present invention.  FIG. 11A  is an external perspective view of a guiding member according to an aspect of the present invention.  FIG. 11B  is a cross-sectional view of the guiding member according to an aspect of the present invention.  FIG. 12A  and  FIG. 12B  are external perspective views as viewed from different directions according to an aspect of the present invention.  FIG. 13A  and  FIG. 13B  are enlarged perspective views of a front end portion of the cleaning rod as viewed from different directions according to an aspect of the present invention.  FIG. 14A  and  FIG. 14B  are enlarged perspective views of the rear end portion of the cleaning rod as viewed from different directions according to an aspect of the present invention.  FIG. 15  is an external perspective view of a pad according to an aspect of the present invention. 
     Referring to  FIG. 1 , the image forming apparatus employed in the present invention includes: a cleaning mechanism  10 ; an optical scanning unit  120 ; a loading portion  150  onto which the optical scanning unit  120  detachably loaded; a photosensitive drum  200  serving as an image holding body; a development unit  210 ; a cleaner unit  220 ; a transferring unit  230 ; a charging unit  240 ; intermediate transferring belt  250 ; and the like. The optical scanning unit  120  scans and exposes a beam BM between the charging unit  240  and the development unit  210  on the photosensitive drum  200 . The above-described components are installed in a frame, not shown, which defines an external outline of the image forming apparatus. 
     A description will now be given of a fundamental movement of the image forming apparatus. The photosensitive drum  200  is uniformly charged by the charging unit  240 . The charged surface of the photosensitive drum  200  is scanned by the beam BM from the optical scanning unit  120 , and a latent image is formed. Next, the latent image formed on the photosensitive drum  200  is developed with toner by the development unit  210 , and the toner image developed on the photosensitive drum  200  is transferred to the intermediate transferring belt  250  by the transferring unit  230 . Then, the untransferred remaining toner, which is not transferred to the intermediate transferring belt  250  and remains on the photosensitive drum  200 , is removed from the photosensitive drum  200  by the cleaner unit  220 . The toner image transferred to the intermediate transferring belt  250  is transferred to a recording medium such as a paper by a mechanism, not shown. 
     Referring now to  FIG. 2 , the chassis of the optical scanning unit  120  is composed of: a housing member  121  that includes various parts therein; and a cover  122  that covers an upper portion of the housing member  121 . The chassis of the optical scanning unit  120  defines an external outline. The cover  122  is provided with a seal glass  123  serving as a light transmitting portion that transmits a light. The seal glass  123  has the surface formed substantially identical to the surface of the cover  122 . The housing member  121  and the cover  122  may be formed by use of a material such as resin, metal, or the like. 
     The optical scanning unit  120  is loaded onto the loading portion  150  in a loading direction F shown in  FIG. 2 , and is fixed at a base surface, not shown, of the loading portion  150 . 
     The optical scanning unit  120  includes various optical parts, not shown, such as a semiconductor laser, scanning motor, polygon mirror, scanning lens, turn-back mirror, and the like. The beam emitted from the semiconductor laser is reflected by the polygon mirror rotated by the scanning motor, transmits through the scanning lens, is reflected by the turn-back mirror, transmits through the seal glass  123  serving as a light transmitting portion provided at the cover  122 , and is emitted toward the photosensitive drum  200 . 
     Referring now to  FIG. 3  through  FIG. 5 , the cleaning mechanism  10  is opposed to the seal glass  123  (cover  122 ) of the optical scanning unit  120  and arranged along the longitudinal direction of the seal glass  123  so as to be fixed at a frame FR of the image forming apparatus. Normally, the surface of the seal glass  123  of the optical scanning unit  120  is cleaned according to a user&#39;s cleaning operation, described later, while securing the transmission of the beam BM output toward the photosensitive drum  200  from the optical scanning unit  120 , as shown in  FIG. 3 . 
     The cleaning mechanism  10  is composed of: a guide rail member  20 ; a spring member  30 ; a retaining mechanism composed of a guiding member  60  and the like; and a cleaning rod  70  retained by the retaining mechanism. 
     Referring now to  FIG. 6  through  FIG. 10 , for example, the guide rail member  20  is formed by pressing a sheet of metal, and includes: an opening portion  21  formed in the longitudinal direction of the upper surface thereof to transmit the beam BM; guide rails  23  formed in parallel with the longitudinal direction at the bottom surface side thereof, which is a side opposed to the optical scanning unit  120 ; a receiving portion  25  formed to be projected at an end portion thereof to receive the front end portion of the cleaning rod  70 ; an attaching portion  28  formed at an end side of the guide rail member  20 ; and a flange portion  29  formed at the rear end side thereof.  FIG. 6  shows a state in which a plate spring member  30  is fixed at the end portion of the guide rail member  20 . 
     The attaching portion  28  is provided with an elastically deformable engaging projection  28   a  projecting upward, so that the engaging projection  28   a  is attached to the frame FR by inserting the engaging projection  28   a  into an inserting opening, not shown, formed in the frame FR shown in  FIG. 5  to be engaged therewith. The flange portion  29  is fastened and secured to the frame FR by a bolt, not shown. 
     The guide rails  23  are spaced apart from each other and located in parallel with each other, and are provided with end portions  24  tilted and formed upward at ends portions thereof; and guide portions  26  tilted and formed downward at a partway thereof. Since the guide portions  26  are formed at the partway of the guide rails  23 , the guide rails  23  are cut away in the partway. A slide portion  72  of the cleaning rod  70 , described later, is inserted from such cut portion, and is guided by the guide portion  26  onto the guide rails  23 . 
     The receiving portion  25  is tilted toward the lower portion of the guide rail member  20 , and receives the front end portion of the cleaning rod  70 , described later. 
     Referring to  FIG. 10A  and  FIG. 10B , the spring member  30  is composed of: a plate spring portion  31  formed in a cantilever shape; positioning openings  32  and  34  to be positioned at the top surface of the guide rail member  20 ; a through-hole  33  into which a bolt for fastening is inserted; and the like. The plate spring portion  31  of the spring member  30  protrudes from the upper side to the lower side of the guide rail member  20 , as shown in  FIG. 8 , and elastically deforms in engagement with the front end portion of the cleaning rod  70 , described later. 
     Referring to  FIG. 11A  and  FIG. 11B , the guiding member  60  is formed of, for example, a material such as resin or the like so as to guide the cleaning rod  70 , when the cleaning rod  70  is inserted into or pulled out of the cleaning mechanism  10 . The guiding member  60  is fastened and secured at the frame FR by a bolt or the like, not shown. 
     The guiding member  60  is provided with an inserting opening  61  of a substantially rectangular shape so that the cleaning rod  70  can be inserted thereinto. The inserting opening  61  is provided with: a fitting groove  62  into which a reverse insertion preventing projection  73  of the cleaning rod  70 , described later, can be fitted; and an escaping portion  63  through which a pad  80 , described later, can be passed. The cleaning rod  70  cannot be inserted into the inserting opening  61 , unless the cleaning rod  70  is inserted in a direction where the reverse insertion preventing projection  73 , described later, is fitted into the fitting groove  62 . 
     Referring to  FIG. 12A  through  FIG. 14B , the cleaning rod  70  may be formed of, for example, a material such as resin or the like, and is composed of: an opening portion  71  formed in a longitudinal direction thereof so as to transmit the beam BM; the slide portion  72  projected at both sides of the end portion thereof; the reverse insertion preventing projection  73  projected from the upper surface of the end portion thereof; a contact portion  74  that can be engaged with the receiving portion  25  of the guide rail member  20  formed in a plate shape at the front end portion thereof; an engaging projection  75  that projects at both sides of the rear end portion thereof; an engaging projection  76  that projects from the lower surface of the rear end portion thereof; a holding portion  77  formed at the rear end thereof; and the pad  80  secured at the lower surface of the front end portion thereof; and the like. 
     The slide portion  72  can be engaged with the guide rails  23  of the guide rail member  20 , respectively. When the cleaning rod  70  is inserted into the cleaning mechanism  10 , the engaging projection  75  is fitted into the inserting opening  61  of the guiding member  60  to prevent air or dusts outside of the image forming apparatus from entering. 
     When the cleaning rod  70  is inserted to reach the insertion completed position of the cleaning mechanism  10 , the engaging projection  76  is engaged with the guiding member  60  to prevent the cleaning rod  70  from being pulled out of the inserting opening  61 . 
     The holding portion  77  projects from the rear end portion to be capable of holding the cleaning rod  70 , when a user inserts or pulls the cleaning rod  70  into or out of the cleaning mechanism  10 . 
     The contact portion  74  is formed in a plate shape and is also tilted in alignment with the inclination of the receiving portion  25  of the guide rail member  20 . This makes it possible to move the cleaning rod  70  smoothly and thereby stabilizing the position thereof, when the contact portion  74  slides in contact with the receiving portion  25 . 
     Referring now to  FIG. 15 , the pad  80  is composed of: a base  81  made of resin and secured at the lower surface of the front end portion of the cleaning rod  70 ; an elastic member  82  made of urethane sponge or the like secured at the base  81 ; a cleaning member  83  made of nonwoven fabric or the like secured at a surface of the elastic member  82  to clean the surface of the seal glass  123  of the optical scanning unit  120 ; and the like. 
     The pad  80  is exchangeably attached by snap fitting an engaging projection  81   a  formed at the base  81  onto the front end portion of the cleaning rod  70 . 
     Next, referring to  FIG. 16A  through  FIG. 18B , a description will be given of an operation example of the cleaning mechanism  10  when the cleaning rod  70  is inserted. 
     Firstly, when the cleaning rod  70  is inserted into the inserting opening  61  of the guiding member  60  from the state where the cleaning rod  70  is outside of the cleaning mechanism  10 . As shown in  FIG. 16A , the slide portion  72  of the cleaning rod  70  moves on the guide rails  23 . 
     As the cleaning rod  70  is further inserted and the front end thereof reaches a portion where there is no guide rail  23  provided in the proximity of the guide portion  26 , as shown in  FIG. 16B , the contact portion  74  arranged at an end of the cleaning rod  70  moves onto the guide rails  23  again provided at the front side of the portion where there is no guide rail  23  provided, before the slide portion  72  drops into the portion where there is no guide rail  23  provided. This will not cause the slide portion  72  to be dropped into a discontinuous portion formed by the guide portion  26 . 
     As the cleaning rod  70  is further inserted, the slide portion  72  moves sliding on the guide rails  23 , as shown in  FIG. 17A . At this time, the pad  80  moves at a given height spaced apart from the surface of the seal glass  123  between the guide rails  23  opposing each other. 
     Then, as shown in  FIG. 17B , when the slide portion  72  of the cleaning rod  70  moves onto the end portions  24  of the guide rails  23 , the front end portion of the cleaning rod  70  moves upward and comes into contact with the plate spring portion  31 , since the end portions  24  are tilted upward. Then, the plate spring portion  31  is elastically deformed. In this manner, a biasing force of the plate spring portion  31  is exerted downward at the front end portion of the cleaning rod  70 . 
     As the cleaning rod  70  is further inserted, the slide portion  72  of the cleaning rod  70  moves away from the end portions  24  of the guide rails  23 , as shown in  FIG. 18A . However, the receiving portion  25  of the guide rail member  20  receives the contact portion  74  of the cleaning rod  70 . 
     As the cleaning rod  70  is further inserted, the contact portion  74  moves upward on the receiving portion  25  that is tilted, as shown in  FIG. 18B . Then, the front end portion of the cleaning rod  70  moves upward in a direction apart from the optical scanning unit  120 , and in the end the movement thereof is regulated by the receiving portion  25 . In this state, the engaging projection  76  formed at the back end portion of the cleaning rod  70  is engaged with a portion of the guiding member  60 . This position is referred to as insertion completed position of the cleaning rod  70 . 
     The front end portion of the cleaning rod  70 , including the pad  80 , is located above the cover  122  of the optical scanning unit  120 , and is held by the receiving portion  25  with certainty in the state shown in  FIG. 18B . This makes it possible to prevent the cleaning rod  70  and the optical scanning unit  120  from interfering with each other at the time of exchanging the optical scanning unit  120  at the loading portion  150 . 
     Next, referring to  FIG. 19A  through  FIG. 20B , a description will be given of an operation example of the cleaning mechanism  10  when the cleaning rod  70  is pulled (for cleaning). 
     Firstly, referring now to  FIG. 19A , when the cleaning rod  70  is pulled to the outside of the cleaning mechanism  10  from the state shown in  FIG. 18B , the front end portion of the cleaning rod  70  recedes. The contact portion  74  of the cleaning rod  70  moves downward in a direction of approaching the cover  122  of optical scanning unit  120 , while sliding downward the tilted surface of the receiving portion  25 . Then, the pad  80  is brought into contact with the surface of the cover  122 . The slide portion  72  of the cleaning rod  70  is inserted into a gap between the guide rails  23  and the cover  122  by being guided by the end portions  24  that are tilted of the guide rails  23 . When (the upper surface) of the slide portion  72  is engaged (contact) with (the lower surfaces) of the guide rails  23 , the elastic member  82  of the pad  80  is compressed to have a given thickness and the cleaning member  83  is pushed to the cover  122  by a constant suppress strength. 
     Referring now to  FIG. 19B , when the cleaning rod  70  is further pulled to the outside of the cleaning mechanism  10  from the state shown in  FIG. 19A , the pad  80  slides on the surface of the seal glass  123  from the state shown in  FIG. 19A . This cleans the surface of the seal glass  123 . 
     The pad  80  passes through the surface of the seal glass  123 , moves onto the surface of the cover  122  again, and the cleaning process is completed. Referring now to  FIG. 20A , the slide portion  72  of the cleaning rod  70  moves onto the guide portions  26 , and is again guided onto the guide rails  23 . 
     Referring now to  FIG. 20B , as the cleaning rod  70  is further pulled to the outside of the cleaning mechanism  10 , the cleaning rod  70  is completely drawn from the cleaning mechanism  10 . 
     In the above-described embodiment, the description has been given of the case where the receiving portion  25  and the guide portions are integrally formed with the guide rail member  20 . However, the present invention is not limited to this. The receiving portion  25  and the guide portions may be formed separately from the guide rail member  20 . 
     In the above-described embodiment, the description has been given of the case where the seal glass  123  is cleaned at the time of pulling the cleaning rod. However, the present invention is not limited to this. The seal glass  123  may be cleaned at the time of inserting the cleaning rod  70 , and then the front end portion of the cleaning rod may be held at the insertion completed position, so that the pad is spaced apart from the optical scanning unit  120  and above the optical scanning unit  120 . 
     The foregoing description of the exemplary embodiments 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 exemplary embodiments were 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. 
     CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2006-027798 filed on Feb. 3, 2006.