Patent Publication Number: US-10761477-B2

Title: Image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This patent application is based on and claims priority pursuant to 35 U.S.C. § 119(a) to Japanese Patent Application No. 2018-205915, filed on Oct. 31, 2018, in the Japan Patent Office, the entire disclosure of which is incorporated by reference herein. 
     BACKGROUND 
     Technical Field 
     Embodiments of the present disclosure relate to an image forming apparatus. 
     Discussion of the Background Art 
     An image forming apparatus is known in which a fixing unit is attachable to and detachable from an apparatus body of the image forming apparatus. Such a configuration can simplify removal of a jam sheet and facilitate maintenance, inspection, and replacement of parts by improving attaching and detaching workability. 
     SUMMARY 
     According to an embodiment of this disclosure, an image forming apparatus includes an apparatus body including a body side connector and a removable unit to be removably inserted in the apparatus body in an insertion direction. The removable unit includes a unit side connector configured to engage with the body side connector in conjunction with insertion of the removable unit into and from the apparatus body in the insertion direction and disengage from the body side connector in conjunction with removal of the removable unit from the apparatus body in a removal direction. The apparatus further includes a first holder and a second holder. The first holder is configured to hold the body side connector and restrict the body side connector from moving in the insertion direction and the removal direction relative to the first holder. The second holder is configured to hold the first holder and restrict the first holder from moving in a direction different from the insertion direction and the removal direction. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The aforementioned and other aspects, features, and advantages of the present disclosure would be better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a diagram illustrating a configuration of an image forming apparatus according to an embodiment of the present disclosure; 
         FIG. 2  is a schematic cross-sectional view of a fixing unit provided so as to be insertable into and removable from the image forming apparatus of  FIG. 1 ; 
         FIG. 3  is a plan view of the fixing unit of  FIG. 1  with an upper part of an exterior removed; 
         FIG. 4  is a perspective view of a front surface side of the fixing unit of  FIG. 1  as seen obliquely from above; 
         FIG. 5  is a side view of the fixing unit of  FIG. 1  as seen from the left; 
         FIG. 6  is a schematic cross-sectional view of an apparatus body in a state in which the fixing unit of  FIG. 1  is attached to the apparatus body; 
         FIGS. 7A and 7B  are views for explaining a fitting configuration of drawer connectors according to a comparative example; 
         FIG. 8  is a perspective view of a main part illustrating a holding configuration of an apparatus body side drawer connector according to the example; 
         FIG. 9A  is a cross-sectional view of the main part taken along line S 9 -S 9  of  FIG. 9B  and illustrates the holding configuration of the apparatus body side drawer connector according to the example; 
         FIG. 9B  is a front view of the main part illustrating an attaching and holding relationship relative to a connector holding bracket of the apparatus body side drawer connector of  FIG. 8 ; 
         FIG. 10A  is a cross-sectional view of the main part, taken along line S 10 -S 10  of  FIG. 10B , and illustrates the holding configuration of the apparatus body side drawer connector according to the example; 
         FIG. 10B  is a front view of the main part illustrating an attaching and holding relationship relative to an apparatus body frame member of the apparatus body side drawer connector via the connector holding bracket of  FIG. 8 ; and 
         FIG. 11  is a cross-sectional view of a main part illustrating a holding configuration of an apparatus body side drawer connector according to a variation. 
     
    
    
     The accompanying drawings are intended to depict embodiments of the present disclosure and should not be interpreted to limit the scope thereof. The accompanying drawings are not to be considered as drawn to scale unless explicitly noted. 
     DETAILED DESCRIPTION 
     In describing embodiments illustrated in the drawings, specific terminology is employed for the sake of clarity. However, the disclosure of this patent specification is not intended to be limited to the specific terminology so selected and it is to be understood that each specific element includes all technical equivalents that operate in a similar manner and achieve similar results. 
     Although the embodiments are described with technical limitations with reference to the attached drawings, such description is not intended to limit the scope of the disclosure and all of the components or elements described in the embodiments of this disclosure are not necessarily indispensable. 
     Referring now to the drawings, embodiments of the present disclosure are described below. In the drawings for explaining the following embodiments, the same reference codes are allocated to elements (members or components) having the same function or shape and redundant descriptions thereof are omitted below. 
       FIG. 1  is a schematic view of an image forming apparatus according to an embodiment of the present disclosure. Referring to  FIG. 1 , a configuration and operation of the image forming apparatus according to the present embodiment are described below. 
     An image forming apparatus illustrated in  FIG. 1  is a monochrome image forming apparatus. A process unit  1  serving as an image forming unit is removably installed in an apparatus body  100 . The process unit  1  includes a photoconductor  2  serving as an image bearer to bear images, a charging roller  3  serving as a charger to charge the surface of the photoconductor  2 , a developing device  4  to develop a latent image on the photoconductor  2  into a visible image, and a cleaning device including a cleaning blade  5  to clean the surface of the photoconductor  2 . The process unit  1  further includes a light-emitting diode (LED) head array  6  disposed opposite the photoconductor  2 . The LED head array  6  serves as an exposure device that exposes the outer surface of the photoconductor  2 . 
     The process unit  1  includes a toner cartridge  7  that is removably mounted in the apparatus body  100 . The toner cartridge  7  serves as a powder container that contains powder toner for forming an image. The toner cartridge  7  includes an unused toner container  8  and a waste toner container  9 . The unused toner container  8  contains unused toner. The waste toner container  9  contains used toner as waste toner. 
     The image forming apparatus further includes a transfer device  10 , a sheet feeder  11 , a fixing device  12 , a sheet ejection device  13 , and a registration roller pair  17 . The transfer device  10  transfers an image onto a sheet P as a recording medium. The sheet feeder  11  feeds or supplies the sheet P. The fixing device  12  fixes the image transferred onto the sheet P by the transfer device  10 . The sheet ejection device  13  ejects the sheet P outside the apparatus. The registration roller pair  17  is a timing roller pair. 
     The fixing device  12  is an example of a removable unit that can be attached to (or inserted into) and removed from the image forming apparatus. 
     The transfer device  10  includes a transfer roller  14  serving as a transfer member. The transfer roller  14  is disposed so as to contact the photoconductor  2  in a state where the process unit  1  is installed inside the image forming apparatus. Additionally, the transfer roller  14  is electrically connected to a power source and receives a predetermined amount of voltage that is either direct-current (DC) voltage, alternating current (AC) voltage, or including both. 
     The sheet feeder  11  includes a sheet feeding tray  15  to contain sheets P and a sheet feeding roller  16  to transport the sheets P. The sheets P may be plain paper, thick paper, thin paper, postcards, envelopes, coated paper, art paper, tracing paper, or the like. In the present embodiment, the sheets P are described as recording media. Alternatively, the recording media may be overhead projector (OHP) transparency (e.g., sheets or films), or the like. 
     The fixing device  12  includes a pair of rotators, that is, a fixing roller  18  (a fixing rotator) to fix an image on the sheet and a pressure roller  19  (an opposing rotator) disposed opposite the fixing roller  18 . The fixing device  12  further includes a heater to heat the fixing roller  18 . The pressure roller  19  is pressed against the fixing roller  18  to form a fixing nip N between the fixing roller  18  and the pressure roller  19  contacting the fixing roller  18 . 
     The sheet ejection device  13  includes a sheet ejection roller pair  20  that ejects the sheets P outside the apparatus. Specifically, the sheet ejection roller pair  20  ejects the sheets P one at a time onto an output tray  21  disposed atop the apparatus body. Thus, the plurality of sheets P lies stacked on the output tray  21 . 
     A conveyance passage R 1  is defined by some internal components of the image forming apparatus. Specifically, the sheet P is conveyed along the conveyance passage R 1  from the sheet feeding tray  15  to the sheet ejection roller pair  20  via the registration roller pair  17 , the transfer nip formed between the transfer roller  14  and the photoconductor  2 , and the fixing device  12 . A duplex conveyance passage R 2  is also defined by some internal components of the image forming apparatus. For duplex printing, the sheet past the fixing device  12  is conveyed along the duplex conveyance passage R 2  again to the transfer nip. 
     A description is now given of the image forming operation of the image forming apparatus the present embodiment, with continued reference to  FIG. 1 . 
     When image formation is started, the photoconductor  2  is rotated, and the charging roller  3  uniformly charges the surface of the photoconductor  2  in a predetermined polarity. The LED head array  6  exposes the outer circumferential surface of the photoconductor  2  thus charged, according to image data sent from a scanner or an external device such as a computer, thereby forming an electrostatic latent image on the outer circumferential surface of the photoconductor  2 . The developing device  4  supplies toner to the electrostatic latent image thus formed on the photoconductors  2 , rendering the electrostatic latent image visible as a toner image. 
     As the image forming operation starts, the sheet feeding roller  16  starts rotating to feed a sheet P from the sheet feeding tray  15  toward the registration roller pair  17 . Then, the registration roller pair  17  stops the sheet P temporarily. Thereafter, activation of the registration roller pair  17  is timed to convey the sheet P to the transfer nip such that the toner image formed on the outer circumferential surface of the photoconductor  2  meets the sheet P at the transfer nip. 
     When the sheet P reaches the transfer nip, a predetermined transfer voltage is applied to the transfer roller  14 , thereby generating a transfer electric field to transfer the toner image from the outer circumferential surface of the photoconductor  2  onto the sheet P. The cleaning blade  5  removes residual toner from the outer circumferential surface of the photoconductor  2 . The residual toner is toner that has failed to be transferred onto the sheet P and therefore remains on the outer circumferential surface of the photoconductor  2 . The waste toner container  9  of the toner cartridge  7  collects the residual toner. 
     After the toner image is transferred onto the sheet P, the sheet P bearing the toner image is conveyed to the fixing device  12 . The fixing device  12  fixes the toner image onto the sheet P under heat and pressure while the sheet P is conveyed through the fixing nip between the fixing roller  18  and the pressure roller  19 . The sheet ejection roller pair  20  ejects the sheet P from the apparatus onto the output tray  21 . 
     In duplex printing, the sheet P bearing the toner image fixed onto a front side thereof in the fixing device  12  is directed to the duplex conveyance passage R 2 , instead of being ejected from the apparatus. The duplex conveyance passage R 2  joins the conveyance passage R 1  upstream from the registration roller pair  17 . The sheet P is conveyed along the duplex conveyance passage R 2  and the conveyance passage R 1  in this order, and the registration roller pair  17  sends out the sheet P to the transfer nip again. At the transfer nip, another toner image is transferred onto a back side of the sheet P and fixed by the fixing device  12 . Thereafter, the sheet P is ejected from the apparatus. 
       FIG. 2  is a schematic cross-sectional view of the fixing device  12 . 
     As illustrated in  FIG. 2 , the fixing device  12  includes a frame member  23  made of resin forming an exterior in which the fixing roller  18  and the pressure roller  19  are accommodated. On a front surface of the frame member  23 , an inlet  23   a  for allowing the paper to enter the fixing device  12  is formed, and on a back surface of the frame member  23 , an outlet  23   b  for ejecting the paper from the fixing device  12  is formed. The “front surface” of the fixing device  12  herein means a front surface of the image forming apparatus in a state in which the fixing device  12  is attached to the image forming apparatus, that is, a surface on a side on which an operator stands when issuing a print instruction by an operating unit (operation panel and the like) provided on the image forming apparatus. In the fixing roller  18 , a halogen heater  22  as a heating element is provided. The pressure roller  19  is pressurized against the fixing roller  18  by a pressurizing member to be described later. The pressure roller  19  and the fixing roller  18  press against each other, and the contact portion therebetween is the fixing nip N. 
     In  FIG. 2 , a unit side drawer connector  70  as a unit side connector is provided in the fixing device  12 . The unit side drawer connector  70  stores a terminal coupled to a feeder  61  or the like illustrated in  FIG. 3  to be described later. A pressed recess  24  receives a pressing force F exerted by a boss on a cover  101  (illustrated in  FIG. 6 ) that opens and is closed relative to the apparatus body  100 . Specifically, the pressed recess  24  receives the pressing force F when the cover  101  is closed such that a fixing gear  18 G (illustrated in  FIG. 3 ) of the fixing device  12  inserted in the apparatus body  100  meshes with a driving gear of the apparatus body  100 . 
       FIG. 3  is a plan view of the fixing device  12  with an upper part of the exterior thereof removed. 
     As illustrated in  FIG. 3 , on one end of the fixing roller  18 , the fixing gear  18 G for connecting to the driving gear provided on the apparatus body  100  is provided. Therefore, in a state in which the fixing device  12  is attached to the apparatus body  100  and the fixing gear  18 G is coupled to the driving gear, when a driving force is transmitted from a driving source on the apparatus body  100  side to the fixing roller  18 , the fixing roller  18  rotary drives clockwise as indicated by an arrow in  FIG. 2 . The pressure roller  19  is configured to be driven to rotate counterclockwise as indicated by an arrow in  FIG. 2  with respect to the fixing roller  18  which rotary drives. Thus, as the fixing roller  18  rotates driving the pressure roller  19 , the sheet is conveyed while being nipped between the rollers  18  and  19 . Contrary to this embodiment, the pressure roller  19  may be the driving roller, and the fixing roller  18  may be the driven roller. 
     In  FIG. 3 , an insulating base member  60  made of ceramics or the like is attached to an end of each halogen heater  22  described above, and the feeder  61  is coupled to the end of each halogen heater  22  for supplying power from a power source on the apparatus body  100  side to each halogen heater  22 . 
     Operation of the fixing device  12  is briefly described with reference to  FIG. 2 . 
     In a state in which the fixing roller  18  is heated to predetermined temperature by radiant heat emitted from the halogen heater  22  and the fixing roller  18  and the pressure roller  19  rotate, when the paper enters the fixing nip N in a direction indicated by an arrow C 1  in  FIG. 2 , the paper is conveyed while being nipped between the fixing roller  18  and the pressure roller  19 . At that time, an unfixed image on the paper is heated by the heat of the fixing roller  18  and pressurized by the fixing roller  18  and the pressure roller  19 , so that the image is fixed on the paper. The paper on which the image is fixed is ejected from the fixing nip N in a direction of an arrow C 2  in  FIG. 2 . 
     A detailed configuration of the fixing device  12  is hereinafter described. 
       FIG. 4  is a perspective view of a front surface side of the fixing device  12  as seen obliquely from above. 
     As illustrated in  FIG. 4 , the frame member  23  is provided with a first handle  41  and a second handle  42  gripped by the operator when the fixing device  12  is attached to and detached from the apparatus body  100 . The first handle  41  is provided on each of right and left ends of the back surface of the frame member  23 , and the second handle  42  is provided at the center in a horizontal direction of an upper surface of the frame member  23 . 
     A pair of first handles  41  is formed to be symmetrical to each other. Specifically, each first handle  41  includes a grip  41   a  extending in a vertical direction and a pair of arms  41   b  extending forward (toward the front surface) from upper and lower ends of the grip  41   a , and the grip  41   a  is secured to the back surface of the frame member  23  via the pair of arms  41   b . Between each grip  41   a  and the back surface of the frame member  23 , a space S 1  in which the operator may insert his/her hand or finger is formed. 
     The second handle  42  is provided so as to be rotatable (that is, pivotable) within a range of a predetermined angle with respect to the frame member  23 . Specifically, the second handle  42  has a grip  42   a  extending horizontally and a pair of arms  42   b  extending in a direction orthogonal to or intersecting with the grip  42   a , and a tip end of each arm  42   b  is pivotably attached to the frame member  23  via a support shaft  43 . Since the second handle  42  pivots about the support shaft  43 , the second handle  42  is switched between a fallen state illustrated in  FIG. 4  and an upright state. In the state illustrated in  FIG. 4 , the second handle  42  is accommodated in a concave accommodating portion provided on an upper portion of the frame member  23 . In contrast, in the upright state of the second handle  42 , the second handle  42  projects outward (upward) from an accommodated state illustrated in  FIG. 4  and is brought into a usage state in which this is usable as the handle. That is, in the usage state, a space in which the operator may insert his/her hand or finger to grip the grip  42   a  is formed between the grip  42   a  of the second handle  42  and the upper surface of the frame member  23  is formed. 
     In the accommodating portion, two concave portions  45  and  46  are provided to make it easy to hook the finger on the second handle  42  when the second handle  42  is switched from the accommodated state to the usage state. One is a first concave portion  45  formed by recessing the center of a rear end edge of the accommodating portion  44  forward, and the other is a second concave portion  46  formed by recessing the center of an upper surface of the accommodating portion  44  downward. 
     As illustrated in  FIG. 4 , the frame member  23  is further provided with a plurality of positioning portions for positioning the fixing device  12  with respect to the apparatus body  100 . The plurality of positioning portions includes first positioning projections  47  provided on right and left ends on the front surface of the frame member  23 , a pair of second positioning projections  48  provided on a front surface side of a left side surface and a right side surface of the frame member  23 , and a pair of third positioning projections  49  provided on a back surface side of the left side surface and the right side surface of the frame member  23 . 
     When the fixing device  12  is attached to the apparatus body  100  to occupy an attachment position, a positioning abutment surface  47   a  (refer to  FIG. 2  and the like) on a base of the first positioning projection  47  abuts a positioning abutment surface  105   a  (refer to  FIG. 6 ) as an apparatus body side positioning portion of an apparatus body frame member  105  adhered to the apparatus body  100  side, so that the fixing device  12  is positioned in an insertion and removal direction (hereinafter, also simply “insertion direction” or “Z direction”). 
     On each of the left side surface and the right side surface of the frame member  23 , a guide projection  50  as a convex guide guided along an apparatus body side guide to be described later when the fixing device  12  is attached to or detached from (inserted into/removed from) the apparatus body  100  is provided. Each guide projection  50  is formed into a rectangular shape (substantially rectangular or substantially square) and upper and lower flat surfaces of which serve as an upper sliding surface  50   a  and a lower sliding surface  50   b  which slide on the apparatus body side guide. In this embodiment, when the fixing device  12  is attached/detached (inserted/removed), portions other than the guide projection  50  in the fixing device  12  are prevented from sliding with respect to the apparatus body  100  (exhibiting a guide function), so that a sliding resistance is reduced and operability is improved. 
       FIG. 5  is a side view of the fixing device  12  as seen from the left. 
     As illustrated in  FIG. 5 , the fixing device  12  is provided with a lock  53  which secures the fixing device  12  so as not to be detached in a state of being attached to the apparatus body  100 . The lock  53  is provided on a part of the rotary member  51  rotatably (pivotably) provided on the first handle  41 . The rotary member  51  is formed into a substantially shape, and the lock  53  is provided on a tip end of a portion extending forward (toward the front surface) from a pivoting center (fulcrum  52 ) thereof. A portion extending upward from the pivoting center (fulcrum  52 ) of the rotary member  51  is an operating unit  54  for allowing the operator to perform rotating operation on the rotary member  51 . 
     The lock  53  is always biased downward by a compression coil spring  55  as a biasing member arranged between an upper surface thereof and a lower surface of the frame member  23 . Therefore, in a state in which the operator does not perform the rotating operation on the rotary member  51 , a lower portion of the rotary member  51  abuts a bottom  410  of the lower arm  41   b , and a tip end (lower end) of the lock  53  is held in a state significantly projecting downward from the bottom  410  of the lower arm  41   b  (state indicated by solid line in  FIG. 5 ). In this state, the lock  53  is put into a lockable state engageable with an engaging portion to be described later provided on the apparatus body  100  side. 
     In contrast, in a case where the operator rotates the rotary member  51  counterclockwise in  FIG. 5  against a biasing force of the compression coil spring  55 , the tip end of the lock  53  retracts upward to put into an unlockable state (state indicated by dashed-two dotted line in  FIG. 5 ) in which this does not engage with the engaging portion on the apparatus body  100  side. In this manner, when the operator operates the operating unit  54  to rotate the rotary member  51 , it is possible to switch the lock  53  between the lockable state and the unlockable state. The rotary member  51  is similarly provided on the first handle  41  on the right side. 
       FIG. 6  is a schematic cross-sectional view of the apparatus body in a state in which the fixing unit is attached to the apparatus body. 
     As illustrated in  FIG. 6 , the cover  101  is disposed on a back side (the face on the left side in the drawing) of the apparatus body  100 . The cover  101  rotates (pivots) in the direction indicated by arrow H in  FIG. 6  to be opened and closed. The state illustrated in  FIG. 6  is a state in which the cover  101  is opened and an opening  102  is formed on the back surface of the apparatus body  100 . In this state, the fixing device  12  may be detached backward from the opening  102 . A method of attaching and detaching the fixing device  12  is described later in detail. 
     The cover  101  is integral with a sheet reversal unit  104  which forms a part of the sheet reversal passage R 2 . Therefore, as illustrated in  FIG. 6 , when the cover  101  is opened, the sheet reversal unit  104  rotates (pivots) together with the cover  101  and retracts from the vicinity of the back surface of the fixing device  12 . 
     On inner surfaces of a left side wall and a right side wall of the apparatus body  100 , a pair of guide rails  103  is provided. The guide rails  103  serve as the apparatus body side guides and guide attaching and detaching of the fixing device  12  to and from the apparatus body  100 . Each guide rail  103  includes an upper guide surface  103   a  and a lower guide surface  103   b . When the fixing device  12  is attached or detached, the upper sliding surface  50   a  and the lower sliding surface  50   b  of the guide projection  50  slide on the upper guide surface  103   a  and the lower guide surface  103   b , so that the fixing device  12  is guided. 
     As illustrated in  FIG. 6 , the apparatus body  100  is provided with a plurality of apparatus body side positioning portions for positioning the fixing device  12  with respect to the apparatus body  100 . The plurality of apparatus body side positioning portions includes a first apparatus body side positioning portion  108  which engages with the first positioning projection  47  provided on the fixing device  12  to mainly position the fixing device  12  in a horizontal direction (hereinafter, also referred to as an “X direction”), a front-back direction, or the insertion and removal direction (the above-described Z direction) in  FIG. 4 , a second apparatus body side positioning portion  109  which engages with the second positioning projection  48  provided on the fixing device  12  to mainly position the fixing device  12  in an anterior direction and a vertical direction (hereinafter also referred to as a “Y direction”), and a third apparatus body side positioning portion  110  which engages with the third positioning projection  49  provided on the fixing device  12  to mainly position the fixing device  12  in a rotational direction around the second positioning projection  48 . 
     The apparatus body  100  is also provided with an engaging portion  111  with which the lock  53  of the fixing device  12  engages. The state illustrated in  FIG. 6  is a state in which the lock  53  engages with the engaging portion  111 , and in this state, the fixing device  12  is positioned in a posterior direction, and movement in a detaching direction is restricted. An attaching/detaching, method of the fixing device  12  and an advantage thereof are substantially similar to those disclosed in paragraphs 0079 to 0093 of US-20180067431-A1 (U.S. Pat. No. 10,036,987-B2) by the present applicant. 
     As described above, in this embodiment, the fixing device  12  is configured to be insertable into/removable from the apparatus body  100 , thereby improving fixing device  12  attachability to/detachability from the apparatus body  100 . In this manner, operability of the fixing device  12  at the time of maintenance and inspection is improved. 
     The fixing device  12  is configured to be attached to the apparatus body  100  with a certain amount of play by a lever member, various positioning members, and the like. The insertion and removal direction of the fixing device  12  (Z direction), an engagement direction to an apparatus body side drawer connector (to be described later with reference to  FIGS. 7A and 7B ) provided on the apparatus body  100  side which fits to the unit side drawer connector  70  illustrated in  FIGS. 2, 5  and the like (insertion and removal direction and Z direction, too), and a direction in which the fixing device  12  is pressed (insertion and removal direction and Z direction, too) coincide with one another. As an abutment position of the fixing device  12  is determined on an abutment surface of the first apparatus body side positioning portion  108  on the apparatus body  100  side illustrated in  FIG. 6 , a position between the driving gear on the apparatus body  100  side and the fixing gear  18 G on the fixing device  12  side is determined, so that driving can be transmitted as illustrated in  FIG. 3 . 
     Referring to  FIGS. 7A and 7B , a comparative example regarding a fitting configuration of drawer connectors is described.  FIG. 7A  illustrates a configuration and operation when the drawer connectors are fitted without disadvantage in the comparative example, and  FIG. 7B  illustrates a configuration and operation when the drawer connectors cause a disadvantage such as breakage in the comparative example. 
       FIGS. 7A and 7B  schematically illustrates, as an end view, a cross-section of the unit side drawer connector  70  secured to a frame member  23  on the fixing device  12  side (indicated with parentheses in  FIGS. 7A and 7B ). In  FIGS. 7A and 7B , an apparatus body frame member  105  and the like fixed to the apparatus body  100  are simplified or schematically illustrated. In the comparative example, an apparatus body side drawer connector  80  is attached to the apparatus body frame member  105 . In  FIG. 6  described above, the unit side drawer connector  70  and the apparatus body side drawer connector  80  attached to the apparatus body frame of the embodiment are not illustrated for simplifying the illustration. From the same point of view the illustration of a terminal shape with which the unit side drawer connector  70  and the apparatus body side drawer connector  80  fit is entirely omitted in an embodiment including an example to be described later. 
     As illustrated in  FIG. 7A , the mechanism for engagement (inserting/removing and fitting) of the apparatus body side drawer connector  80  with the unit side drawer connector  70  includes the apparatus body side drawer connector  80 , a stepped screw  90 , and a compression coil spring  91 . The unit side drawer connector  70  and the apparatus body side drawer connector  80  are ready-made drawer connectors. The unit side drawer connector  70  is a female type (receptacle) having a concave shape, and the apparatus body side drawer connector  80  is a male type (plug) having a convex shape. 
     The unit side drawer connector  70  is positioned in three-dimensional directions of an X direction, a Y direction, and a Z direction on the frame member  23  on the fixing device  12  side, and is secured by a fastening member such as a screw. The same applies to the structure according to the embodiment described later. 
     The apparatus body side drawer connector  80  includes an attachment seat  80   a  integral therewith. A plurality of (two in  FIGS. 7A and 7B ) attaching holes  80   b  for attaching the apparatus body side drawer connector  80  is formed on the attachment seat  80   a . The stepped screw  90  includes an outer diameter portion  90   a  having a predetermined clearance with respect to an inner diameter of the attaching hole  80   b , a screw portion  90   b  in which a male screw to be fastened to a female screw on the apparatus body frame member  105  is formed, and a flange  90   c  on which a fastening shape fastened by a tool is formed having an outer diameter larger than the inner diameter of the attaching hole  80   b  of the apparatus body side drawer connector  80  integrally formed. 
     As illustrated in  FIG. 7A , the apparatus body side drawer connector  80  is configured to nip the compression coil spring  91  between the flange  90   c  of the stepped screw  90  and the attachment seat  80   a  of the apparatus body side drawer connector  80 , thereby pressing to hold the apparatus body side drawer connector  80  to make the apparatus body side drawer connector  80  freely movable in the X direction, the Y direction, and the Z direction (three-dimensional directions). In other words, the comparative holding structure of the apparatus body side drawer connector  80  is configured to cause over stroke, in particular, in the Z direction which is the insertion and removal direction. 
     Therefore, posture deviation of the unit side drawer connector  70  when inserting the fixing device  12  into the apparatus body is absorbed, and the connectors of the unit side drawer connector  70  and the apparatus body side drawer connector  80  can be fitted in the positioned state. As a result, it is possible to prevent contact failure due to rubbing or scraping of the connector terminals because of motion to slide also in the Z direction and a force to separate the drawer connectors applied to the unit side drawer connector  70  fitting to the apparatus body side drawer connector  80  by thermal contraction of the fixing device  12 , slight vibration at the time of operation, reverse operation of a driving unit and the like. That is, electrical contact can be maintained without abrasion of the drawer connectors. 
     As illustrated in  FIGS. 7A and 7B , a harness  82  for supplying power to the fixing device  12  is coupled to the apparatus body side drawer connector  80 , but since the fixing device  12  uses a primary power source, this has a larger harness diameter and stronger stiffness as the harness  82  for power supply, so that when this is arranged in a space-saving manner, a force to fall to the apparatus body side drawer connector  80  acts by a load by bending of the harness  82 . 
     Here, as illustrated in  FIG. 7B , a holding mechanism of a conventional configuration of the apparatus body side drawer connector  80  is free about inclination in the X direction, the Y direction, and the Z direction (three dimensional directions), so that a holding posture of the apparatus body side drawer connector  80  with respect to the apparatus body frame member  105  changes depending on the stiffness of the harness  82 , and the drawer connectors do not align when inserting/removing the fixing device  12  (in particular, when inserting) and there is a fear or failure that the drawer connector is damaged as denoted by a reference sign D. As illustrated in  FIG. 7B , the fall of the apparatus body side drawer connector  80  remarkably occurs in particular in the Y direction which is a short direction of the drawer connector. 
     In order to prevent the above-described failure, a biasing force (spring force) of the compression coil spring  91  attached the apparatus body side drawer connector  80  can be strengthened, but a strong spring force is required for sufficiently correct the posture of the apparatus body side drawer connector  80  and a force to strongly push back the fixing device  12  is generated when attaching the fixing device  12 , so that a distance between fixing gears  18 G described with reference to  FIG. 3  becomes larger and driving force transmission becomes poor. 
     In order to prevent the above-described failure and disadvantage, a pressing force F by the cover  101  described with reference to  FIG. 2  can be increased. However, in a case where the pressing force F by the cover  101  is increased, heat of the fixing device  12  is received in a state where a large load is applied to the cover  101  arranged in the vicinity of the fixing device  12 , and the cover  101  deforms due to deterioration with time and the fixing device  12  is displaced, resulting in poor driving force transmission. 
     Referring to  FIGS. 8 to 10B , a structure to solve the above-described disadvantage in the comparative example is described.  FIG. 8  is a perspective view of a main part of a holding configuration of the apparatus body side drawer connector according to the present embodiment.  FIG. 9A  is a cross-sectional view taken along line S 9 -S 9  of  FIG. 9B , and  FIG. 9B  is a front view of a main part including a partial cross-section (stepped screw  95 ) illustrating an attaching/holding relationship with respect to a connector holding bracket of the apparatus body side drawer connector of  FIG. 8 .  FIG. 10A  is a cross-sectional view taken along line S 10 -S 10  of  FIG. 10B , and  FIG. 10B  is a front view of the main part including a partial cross-section (stepped screw  97 ) illustrating an attaching/holding relationship with respect to the apparatus body frame member of the apparatus body side drawer connector via the connector holding bracket of  FIG. 8 . 
     As illustrated in  FIG. 8 , the apparatus body side drawer connector  80  which can be inserted into and removed from the unit side drawer connector  70  illustrated in  FIGS. 7A and 7B  in the Z direction is attached to a connector holding bracket  85  by the two stepped screws  95 . The connector holding bracket  85  is attached to the apparatus body frame member  105  by two stepped screws  97 . The connector holding bracket  85  is a novel member which is not used in the comparative example described above, and is indicated by a mat (sand) pattern including a cross-section in order to facilitate discrimination in shape from the apparatus body side drawer connector  80  and the apparatus body frame member  105 . The connector holding bracket  85  is molded as a single piece with a heat-resistant resin. 
       FIGS. 8, 9A, and 9B  illustrate a projection  80   c  that prevents erroneous assembling of front and back sides of the apparatus body side drawer connector  80 . 
     In  FIGS. 8 to 10B , the apparatus body frame member  105  includes a guide boss  105   b  (a projection), and the connector holding bracket  85  includes a guide boss hole  85   c . As the guide boss  105   b  engages with and fits in the guide boss hole  85   c , the connector holding bracket  85  is guided so as to move in the Z direction with respect to the apparatus body frame member  105  as described later. The apparatus body frame member  105  has a three dimensional shape including a reinforcing rib so as to serve as an attaching member. However, as compared with the connector holding bracket  85  or the apparatus body side drawer connector  80 , the apparatus body frame member  105  is schematically illustrated, that is, the outline thereof is illustrated with a thinner line. 
     Here, the two stepped screws  95  and the connector holding bracket  85  serve as a first holder for holding the apparatus body side drawer connector  80 . The two stepped screws  97  and the apparatus body frame member  105  serve as a second holder for holding the first holder. 
     As illustrated in  FIGS. 9A and 9B , the connector holding bracket  85  is held by the two stepped screws  95 . As illustrated in  FIG. 9B , an outer diameter d 95   a  of a shaft diameter portion  95   a  of each stepped screw  95  is φ3.5 mm, and a diameter d 80   b  of the attaching hole  80   b  of the apparatus body side drawer connector  80  is φ5.0 mm; the apparatus body side drawer connector  80  can move only along the XY plane by this difference of ±0.75 mm. 
     A thickness t 80   a  of the attachment seat  80   a  of the apparatus body side drawer connector  80  is 2.0 mm, and a height h 95  from a lower surface of the flange  95   c  of the stepped screw  95  to a stepped portion of the shaft diameter portion  95   a  is 2.1 mm, so that the apparatus body side drawer connector  80  floats by a clearance of 0.1 mm, and the apparatus body side drawer connector  80  does not fall to the connector holding bracket  85 . 
     As illustrated in  FIGS. 10A and 10B , the connector holding bracket  85  is held by the apparatus body frame member  105  with the two stepped screws  97 . The connector holding bracket  85  is guided by the guide boss  105   b  on the apparatus body frame member  105  so as to be movable only in the Z direction. Attaching holes  85   a  and  85   b  which are fastened portions of the connector holding bracket  85  are held with a predetermined clearance between a shaft diameter portion  97   a  of the stepped screw  97 . 
     As in  FIG. 10B , on the connector holding bracket  85 , an attaching hole  85   a  and a long hole  85   b  for attaching the stepped screw  97  are formed. An outer diameter d 97   a  of the shaft diameter portion  97   a  of the stepped screw  97  is 0.5 mm, a diameter d 85   a  of the attaching hole  85   a  is φ3.6 mm, and a diameter d 85   b  of the long hole  85   b  is φ3.6×5.6 mm. 
     As specifically illustrated in  FIG. 10A , the connector holding bracket  85  is configured as follows. When a screw portion of the steeped screw  97  is fully fastened to the female screw on the apparatus body frame member  105 , a clearance c 85  of 1.0 mm is secured with respect to a length from a flange  97   c  of the stepped screw  97  to a stepped portion of the shaft diameter portion  97   a . By this, the connector holding bracket  85  is movable relative to the apparatus body frame member  105  in a range of 1.0 mm or smaller in the Z direction. 
     In  FIGS. 9 and 10 , a guide boss diameter d 105   b  of the guide boss  105   b  of the apparatus body frame member  105  is φ6.0 mm, and a diameter d 85   c  of the guide boss hole  85   c  of the connector holding bracket  85  through which the guide boss  105   b  is inserted is φ6.1 mm. 
     One of the attaching holes of the connector holding bracket  85  to/into which the stepped screw  97  is attached/inserted can be used as a positioning hole and the other can be used as a rotation stopper without individually providing the guide boss on the apparatus body frame member  105  side. 
     As described above, the two stepped screws  95  and the connector holding bracket  85  (first holder) together hold the apparatus body side drawer connector  80  and restrict the apparatus body side drawer connector  80  from moving in the Z direction which is the insertion and removal direction. Further, the two stepped screws  97  and the apparatus body frame member  105  (second holder) together hold the two stepped screws  95  and the connector holding bracket  85  (first holder) and restrict the two stepped screws  95  and the connector holding bracket  85  from moving in a direction different from the Z direction. 
     Furthermore, the apparatus body side drawer connector  80  is held so as to be movable in the XY plane being the plane orthogonal to the Z direction relative to the two stepped screws  95  and the connector holding bracket  85  (first holder). The two stepped screws  95  and the connector holding bracket  85  (first holder) are held so as to be movable in the Z direction relative to the two stepped screws  97  and the apparatus body frame member  105  (second holder). 
     According to the above-described example, a basic effect can be obtained that connector contactability relative to the movement of the fixing device  12  in the insertion and removal direction is secured by a compact and relatively inexpensive configuration. The apparatus body side drawer connector  80  and the unit side drawer connector  70  can be surely engaged with each other in conjunction with the insertion of the fixing device  12  into the apparatus body  100 . 
     The connector holding bracket  85  is configured not to be displaced, by rotational components in the XY plane and the Z direction, from the apparatus body frame member  105 . Accordingly, the connector holding bracket  85  can follow the apparatus body frame member  105  in the Z direction while preventing damage to the connectors engaged with each other by position adjustment on the XY plane. This configuration can be free of risk of connector abrasion and the like. 
     The apparatus body side drawer connector  80  and the unit side drawer connector  70  are ready-made drawer connectors, and the holders thereof are normally short in straight length in the fitting and insertion and removal direction. Therefore, when used as sliding holders in the fitting direction, these drawer connectors are easily inclined and galling easily occurs. Therefore, when holding the apparatus body side drawer connector  80 , by restricting the movement in a direction parallel to the fitting direction and allowing the movement in the plane orthogonal to the fitting direction, inclination preventing accuracy of the apparatus body side drawer connector  80  is further improved. 
     Referring to  FIG. 11 , a variation of the above-described embodiment is described.  FIG. 11  is a cross-sectional view of a main part illustrating a holding configuration of an apparatus body side drawer connector according to the variation. 
     The variation illustrated in  FIG. 11  is mainly different from the example illustrated in  FIGS. 8 to 10B  in adding a compression coil spring  88  as a pressing member or a biasing member between an outer peripheral surface of a pedestal  105   c  that is integral with the apparatus body frame member  105  and the connector holding bracket  85  located on an outer side thereof. Examples of the biasing member is not limited to springs, but include, for example, a sponge to exert elasticity and a solenoid to exert electromagnetic force. 
     The pedestal  105   c  is integral with the apparatus body frame member  105  and engaged with a screw portion  97   b  of the stepped screw  97  to be screwed. The compression coil spring  88  acts to press the connector holding bracket  85  against the fixing device  12  with a relatively small force when the fixing unit is inserted into an apparatus body as illustrated in  FIG. 11 . In  FIG. 11 , in order to illustrate a characteristic of the present disclosure, it is intentionally illustrated that a clearance c 85  similar to that illustrated in  FIGS. 10A and 10B  occurs. 
     According to the variation, by adding the compression coil spring  88  as the pressing member, the apparatus body side drawer connector  80  is pressed toward the fixing unit with a small force, so that even in a case where a sliding load occurs due to a change in surface state by abrasion over time and contamination of dust, the pedestal  105   c  presses in a balanced manner to be assisted, therefore operation in a Zb direction of the apparatus body side drawer connector  80  is not slow and uncertain. Therefore, connector connection/fitting property can be reliably ensured in accordance with minute vibration of the fixing unit. 
     Although a preferred embodiment of the present disclosure is described above, the present disclosure is not limited to such specific embodiment and example, and can be variously modified/changed without departing from the scope of the present disclosure recited in claims unless limited in particular in the description above. For example, the technical matters described in the above embodiment, example and the like can be appropriately combined. 
     The “removable unit” (insertion/removal unit or attaching/detaching unit) according to the present disclosure is a general term of a unit insertable into and removable from an apparatus body having the unit side connector to be fitted with an apparatus body side connector. Therefore, the insertion/removal unit according to the present disclosure is not limited to the fixing unit described in the above embodiment, but also includes a double-sided unit, an image bearer unit and the like, and can be applied thereto. 
     The effects described in the embodiments of this disclosure are listed as most preferable effects derived from this disclosure, and therefore are not intended to limit to the embodiments of this disclosure. 
     Numerous additional modifications and variations are possible in light of the above teachings. It is therefore to be understood that, within the scope of the above teachings, the present disclosure may be practiced otherwise than as specifically described herein. With some embodiments having thus been described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the scope of the present disclosure and appended claims, and all such modifications are intended to be included within the scope of the present disclosure and appended claims.