Patent Publication Number: US-11042103-B2

Title: Image forming apparatus having optical print head

Description:
BACKGROUND 
     Field 
     The present disclosure relates to an image forming apparatus having an optical print head that is detachably mountable, by being inserted/extracted to/from an apparatus main body. 
     Description of the Related Art 
     There are image forming apparatuses, such as printers, photocopiers, and so forth, that have an optical print head having multiple light emitting elements for exposing a photosensitive drum. Some optical print heads use light-emitting diodes (LEDs), organic light-emitting diodes (OLEDs), or the like, as examples of light emitting elements. There are known arrangements where multiple such light emitting elements are arrayed in one row, or in two staggered rows, for example, along the rotational axis direction of the photosensitive drum. The optical print head also has multiple lenses for condensing light emitted from the multiple light emitting elements on the photosensitive drum. The multiple lenses are placed between the multiple light emitting elements and the photosensitive drum, so as to face the surface of the photosensitive drum along the direction of array of the light emitting elements. 
     Now, the multiple light emitting elements provided to the optical print head emit light in response to drive signals from a control unit provided in the image forming apparatus. Drive signals from the control unit are sent to the optical print head via a cable. Japanese Patent Laid-Open No. 2015-205497 describes using a flexible flat cable (FFC) to supply electric power from the control unit to an exposing unit that has light emitting elements such as LEDs or the like. Japanese Patent Laid-Open No. 2015-205497 also discloses a method of attaching a support bar (support part) having an exposing unit to an image forming apparatus, and a method of detaching the support bar from the image forming apparatus. 
     The exposing unit in Japanese Patent Laid-Open No. 2015-205497 is supported by the support bar formed of sheet metal, for example. When the support bar (support part) is in a state of being attached to the apparatus main body, the support bar (support part) is supported by a support plate. The support plate is fixed to the main body of the apparatus. A control board that controls driving of the exposing unit is also provided to the main body of the apparatus. The control board and the exposing unit are electrically connected by cable. Part of the cable is affixed to the support plate, thereby restricting movement in the direction in which the support bar (support part) moves. 
     In Japanese Patent Laid-Open No. 2015-205497, in a state where the support bar (support part) is accommodated in the main body of the apparatus, the cable has a curved portion of flexing in a U-shape from the rear side of the main body of the apparatus toward the front side (or from the front side toward the rear side) between the support bar (support part) and the support plate. When replacing the exposing unit for maintenance, a worker draws the support bar (support part), located at a mounting position, out to the front side by an amount corresponding to the amount of flexing in the flexing region of the cable, via an opening formed in a front-side plate. The worker then removes the cable from a connector provided to the exposing unit on the rear side of the front-side plate. Thereafter, the worker draws out the support bar (support part) toward the front side, and performs maintenance of the exposing unit, such as replacing the exposing unit with a new one, or the like. 
     The photosensitive drum also is periodically replaced, since it is a consumable item. The worker performs maintenance of the image forming apparatus by replacing a drum unit that includes the photosensitive drum. The drum unit is extracted from and inserted into a side face of the main body of the image forming apparatus, by sliding movement as to the main body of the apparatus. The clearance between the lenses and surface of the photosensitive drum is extremely small at an exposing position (position facing the surface of the drum in close proximity), which is the position of the optical print head when exposing the photosensitive drum. Accordingly, the optical print head and photosensitive drum or the like may come into contact and damage the surface of the photosensitive drum and lenses, unless the optical print head is retracted from the exposing position when replacing the drum unit. Thus, this may be addressed by the image forming apparatus having a mechanism where the optical print head is reciprocally moved between the exposing position and a retracted position of being retracted away from the photosensitive drum, from the exposing position. 
     Japanese Patent Laid-Open No. 2013-134370 discloses a movement mechanism that moves the optical print head between the exposing position and retracted position. A sliding member moves by sliding as to the main body of the apparatus, in conjunction with opening/closing actions of a front cover of the main body of the apparatus in Japanese Patent Laid-Open No. 2013-134370. The optical print head moves between the exposing position and retracted position in conjunction with the sliding movement of the sliding member. That is to say, the optical print head moves between the exposing position and retracted position in accordance with a worker opening and closing the front cover. 
     In a case where the exposing unit in Japanese Patent Laid-Open No. 2015-205497 is configured to move between the exposing position and retracted position as in Japanese Patent Laid-Open No. 2013-134370, a region of the cable between the portion connected to the connector and the portion bent toward the front side below the support bar (support part) also moves in conjunction with this movement. When the exposing unit is in a state of being situated at the retracted position, the amount of this region that is exposed downwards in the vertical direction from an opening formed in the support bar (support part) is greater as compared to a case of the exposing unit being situated at the exposing position. Accordingly, there is increased possibility of this region coming into contact with the edge of the opening formed in the front-side plate, when the worker moves the support bar (support part) by sliding and the connector in a state with the cable connected thereto passes the opening formed in the front-side plate. 
     SUMMARY 
     According to an aspect of the present disclosure, an image forming apparatus includes a photosensitive drum configured to rotate as to an apparatus main body, a print head having a connector, and a light emitting element configured to emit light to expose the photosensitive drum to the emitted light, a movement mechanism configured to move the print head between an exposing position where the light emitting element emits the light and exposes the photosensitive drum, and a retracted position where the print head is retracted to a position farther away from the photosensitive drum than the exposing position, a support part configured to support the movement mechanism, wherein the support part is movable in a rotational axis direction of the photosensitive drum via an opening formed in a front-side plate provided to the front side of the apparatus main body, and wherein the support portion is movable between a mounted position where the print head is mounted to the apparatus main body, and a drawn-out position where the print head has been drawn out from the apparatus main body with the connector situated further to the front side from the opening, a cable configured to be connected to the connector and supply drive signals for driving the light emitting element to the print head, wherein the cable extends toward an opposite side of the connector from a side where the photosensitive drum is disposed, and is bent toward one direction or another direction of the support part in the rotational axis direction at an opposite side of the support part from a side where the photosensitive drum is disposed, and an abutting portion configured to be provided to the support part, and to abut the bent portion of the cable in a direction from the retracted position toward the exposing position to cause the cable to flex at a portion between a connected portion to the connector and the bent portion, in a case where the print head is situated at the retracted position. 
     Further features of the present disclosure will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1A and 1B  are diagrams for describing the configuration of an image forming apparatus. 
         FIGS. 2A and 2B  are diagrams illustrating around drum units and around developing units that the image forming apparatus has. 
         FIG. 3  is a diagram for describing the configuration of an optical print head. 
         FIGS. 4A ,  4 B 1 - 4 B 2 ,  4 C 1 - 4 C 2  are diagrams for describing a board and lens array. 
         FIGS. 5A and 5B  are diagrams for describing a moving mechanism and a first support member. 
         FIGS. 6A and 6B  are diagrams for describing a link mechanism that the moving mechanism has. 
         FIGS. 7A and 7B  are diagrams for describing the configuration of a moving mechanism according to a modification. 
         FIGS. 8A and 8B  are diagrams for describing operations of the moving mechanism according to the modification. 
       FIGS.  9 A 1 - 9 A 2 ,  9 B are diagrams for describing a moving mechanism according to another modification. 
         FIGS. 10A and 10B  are diagrams for describing a moving mechanism using a cam mechanism. 
         FIG. 11  is a diagram for describing an opening formed in the first support member. 
         FIG. 12  is a diagram for describing the first support member and a second support member. 
         FIG. 13  is a diagram for describing the first support member situated at a mounted position. 
         FIG. 14  is a diagram for describing the first support member being moved from the mounted position toward an extracting position. 
         FIG. 15  is a diagram for describing the first support member situated at the extracting position. 
         FIGS. 16A and 16B  are for diagrams describing a cable guide member provided to the first support member. 
         FIGS. 17A and 17B  are diagrams for describing states of the cable in conjunction with movement of the optical print head. 
         FIGS. 18A through 18C  are diagrams for describing the cable. 
         FIG. 19  is a diagram for describing a cable guide member according to a second embodiment. 
         FIGS. 20A and 20B  are diagrams for describing a cable guide member according to a modification. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments for carrying out the present disclosure are described below with reference to the attached drawings. It should be noted, however, that components given in this description are only exemplary, and that the present disclosure is not restricted to just the embodiments given in this description. 
     First Embodiment 
     Image Forming Apparatus 
     First, a schematic configuration of an image forming apparatus  1  will be described.  FIG. 1A  is a schematic cross-sectional view of the image forming apparatus  1 . Although the image forming apparatus  1  illustrated in  FIG. 1A  is a color printer (single function printer (SFP)) that does not have a reader, an embodiment may be a copying machine that has a reader. Also, an embodiment is not restricted to a color image forming apparatus having multiple photosensitive drums  103  as illustrated in  FIG. 1A , and may be a color image forming apparatus having one photosensitive drum  103  or an image forming apparatus that forms monochromatic images. 
     The image forming apparatus  1  illustrated in  FIG. 1A  has four image forming units  102 Y,  102 M,  102 C, and  102 K (hereinafter also collectively referred to as “image forming unit  102 ”) that form toner images of the yellow, magenta, cyan, and black colors. The image forming units  102 Y,  102 M,  102 C, and  102 K respectively have a photosensitive drum  103 Y,  103 M,  103 C, and  103 K (hereinafter also collectively referred to as “photosensitive drum  103 ”). The image forming units  102 Y,  102 M,  102 C, and  102 K also respectively have a charger  104 Y,  104 M,  104 C, and  104 K (hereinafter also collectively referred to as “charger  104 ”) for charging the respective photosensitive drums  103 Y,  103 M,  103 C, and  103 K. The image forming units  102 Y,  102 M,  102 C, and  102 K further respectively have a light-emitting diode (LED) exposing unit  500 Y,  500 M,  500 C, and  500 K (hereinafter also collectively referred to as “exposing unit  500 ”) serving as an exposure light source that emits light to expose the photosensitive drums  103 Y,  103 M,  103 C, and  103 K. Moreover, the image forming units  102 Y,  102 M,  102 C, and  102 K respectively have a developing unit  106 Y,  106 M,  106 C, and  106 K (hereinafter also collectively referred to as “developing unit  106 ”) that develops electrostatic latent images on the photosensitive drum  103  by toner, thereby developing toner images of the respective colors on the photosensitive drums  103 . Note that the Y, M, C, and K appended to the reference numerals indicate the color of the toner. 
     The image forming apparatus  1  illustrated in  FIG. 1A  is an image forming apparatus that employs what is called “bottom-side exposure”, where the photosensitive drum  103  is exposed from below. Although description will be made below assuming an image forming apparatus employing bottom-side exposure, an embodiment may be made where the image forming apparatus employs “top-side exposure”, where the photosensitive drum  103  is exposed from above, as in an image forming apparatus  2  illustrated in  FIG. 1B . Portions in  FIG. 1B  that indicate the same configurations as those in  FIG. 1A  are denoted by the same reference symbols. 
     The image forming apparatus  1  is provided with an intermediate transfer belt  107  onto which toner images formed on the photosensitive drums  103  are transferred, and primary transfer roller  108  (Y, M, C, K) that sequentially transfer the toner images formed on the photosensitive drums  103  onto the intermediate transfer belt  107 . The image forming apparatus  1  further is provided with a secondary transfer roller  109  that transfers the toner image on the intermediate transfer belt  107  onto a recording sheet P conveyed from a sheet feed unit  101 , and a fixing unit  100  that fixes the secondary-transferred image onto the recording sheet P. 
     Image Forming Process 
     The exposing unit  500 Y exposes the surface of the photosensitive drum  103 Y that has been charged by the charger  104 Y. Accordingly, an electrostatic latent image is formed on the photosensitive drum  103 Y. Next, the developing unit  106 Y develops the electrostatic latent image formed on the photosensitive drum  103 Y by yellow toner. The yellow toner image developed on the surface of the photosensitive drum  103 Y is transferred onto the intermediate transfer belt  107  by the primary transfer roller  108 Y. Magenta, cyan, and black toner images are also transferred onto the intermediate transfer belt  107  by the same image forming process. 
     The toner images of each color transferred onto the intermediate transfer belt  107  are conveyed to a secondary transfer position T 2  by the intermediate transfer belt  107 . Transfer bias for transferring the toner images onto a recording sheet P is applied to the secondary transfer roller  109  disposed at the secondary transfer position T 2 . The toner images conveyed to the secondary transfer position T 2  are transferred onto a recording sheet P conveyed from the sheet feed unit  101  by the transfer bias of the secondary transfer roller  109 . The recording sheet P onto which the toner images have been transferred is conveyed to the fixing unit  100 . The fixing unit  100  fixes the toner images onto the recording sheet P by heat and pressure. The recording sheet P subjected to fixing processing by the fixing unit  100  is discharged to a sheet discharge unit  111 . 
     Drum Unit and Developing Unit 
     Drum units  518 Y,  518 M,  518 C, and  518 K (hereinafter collectively referred to as “drum unit  518 ”) that have the photosensitive drum  103  are attached to the image forming apparatus  1 . The drum unit  518  is a cartridge replaced by a worker such as the user, maintenance staff, or the like. The drum unit  518  rotatably supports the photosensitive drum  103 . Specifically, the photosensitive drum  103  is rotatably supported by a frame of the drum unit  518 . Note that the drum unit  518  may be a configuration that does not include the charger  104  or cleaning device. 
     Further attached to the image forming apparatus  1  according to the present embodiment are developing units  641 Y,  641 M,  641 C, and  641 K (hereinafter collectively referred to as “developing unit  641 ”), which are separate from the drum units  518 . The developing units  641  according to the present embodiment are cartridges where the developing units  106  illustrated in  FIG. 1A  and toner containers have been integrated. Each developing unit  106  is provided with a developing sleeve (omitted from illustration) that bears toner. Each developing unit  641  is provided with multiple gears for rotating a screw that agitates the toner and a carrier. When these gears deteriorate due to age or the like, a worker removes the developing unit  641  from the apparatus main body of the image forming apparatus  1  and replaces it. Note that an embodiment of the drum unit  518  and developing unit  641  may be a process cartridge where the drum unit  518  and developing unit  641  are integrated. 
       FIG. 2A  is a perspective view illustrating the schematic configuration around the drum units  518  and around the developing units  641  that the image forming apparatus  1  has.  FIG. 2B  is a diagram illustrating a drum unit  518  being inserted into the image forming apparatus  1  from the outer side of the apparatus main body. 
     The image forming apparatus  1  has a front-side plate  642  formed from sheet metal, and a rear-side plate  643  similarly formed from sheet metal, as illustrated in  FIG. 2A . The front-side plate  642  is a side wall provided to the front side of the image forming apparatus  1 . The front-side plate  642  makes up part of the casing of the apparatus main body at the front side of the main body of the image forming apparatus  1 . The rear-side plate  643  is a side wall provided to the rear side of the image forming apparatus  1 . The rear-side plate  643  makes up part of the casing of the apparatus main body at the rear side of the main body of the image forming apparatus  1 . The front-side plate  642  and rear-side plate  643  are disposed facing each other as illustrated in  FIG. 2A , with sheet metal, serving as beams that are omitted from illustration, crossing therebetween. The front-side plate  642 , rear-side plate  643 , and unshown beams each make up part of a frame of the image forming apparatus  1 . 
     Now, the front side or the front side regarding the image forming apparatus  1  according to the present embodiment or the components thereof is the side where the drum unit  518  is placed into or drawn out (insertion/extraction) of the apparatus main body. This also is the side where the user stands by the image forming apparatus  1  when performing operations thereof. The rear side or rear side is the opposite side from this. 
     Openings are formed in the front-side plate  642 , through which the drum units  518  and developing units  641  can be inserted into and extracted from the front side of the image forming apparatus  1 . The drum units  518  and developing units  641  are mounted through openings to predetermined positions in the main body of the image forming apparatus  1  (mounting positions). The image forming apparatus  1  also has covers  558 Y,  558 M,  558 C, and  558 K (hereinafter collectively referred to as “cover  558 ”) that cover the front side of both the drum units  518  and developing units  641  mounted to the mounting positions. The covers  558  have one end thereof fixed integrally to the main body of the image forming apparatus  1  by a hinge, and are configured to execute pivoting as to the main body of the image forming apparatus  1  on the hinge. Replacement work is completed by a worker opening a cover  558  and extracting a drum unit  518  or developing unit  641  within the main body, inserting a new drum unit  518  or developing unit  641 , and closing the cover  558 . 
     In the following description, the front-side plate  642  side of the apparatus main body is defined as the front side (front side), and the rear-side plate  643  side as the rear side (rear side), as illustrated in  FIGS. 2A and 2B  here. Also, the side where the photosensitive drum  103 Y that forms electrostatic latent images relating to yellow toner images is disposed is defined as the right side, with the photosensitive drum  103 K that forms electrostatic latent images relating to black toner images as a reference. The side where the photosensitive drum  103 K that forms electrostatic latent images relating to black toner images is disposed is defined as the left side, with the photosensitive drum  103 Y that forms electrostatic latent images relating to yellow toner images as a reference. Further, a direction that is perpendicular to the front-and-rear directions and left-and-right directions defined here, and is upward in the vertical direction is defined as the upward direction, and a direction that is perpendicular to the front-and-rear directions and left-and-right directions defined here, and is downward in the vertical direction is defined as the downward direction. The defined front direction, rear direction, right direction, left direction, upward direction, and downward direction, as illustrated in  FIGS. 2A and 2B . Further, the rotational axis direction of the photosensitive drum  103  as used herein is a direction that generally matches the front-and-rear directions illustrated in  FIGS. 2A and 2B . 
     Exposing Unit 
     Next, the exposing unit  500  including the optical print head  105  (an example of a print head) will be described. An example of an exposing method employed in electrophotographic image forming apparatuses is laser-beam scanning exposure, where an irradiation beam of semiconductor laser is scanned using a rotating polygonal mirror or the like, and the photosensitive drum is exposed via an f-theta lens or the like. The “optical print head  105 ” described in the present embodiment is an arrangement used in the LED exposure method where the photosensitive drum  103  is exposed using light emitting elements such as LEDs or the like arrayed in the rotational axis direction of the photosensitive drum  103 , and is not used in the aforementioned laser-beam scanning exposure. 
     The exposing unit  500  described in the present embodiment is disposed below the rotational axis of the photosensitive drum  103  in the vertical direction, and LEDs  503  that the optical print head  105  has expose the photosensitive drum  103  from beneath. Note however, a configuration may be made where the exposing unit  500  is disposed above the rotational axis of the photosensitive drum  103  in the vertical direction, and exposes the photosensitive drum  103  from above (see  FIG. 1B ).  FIG. 3  is a schematic perspective view of the exposing unit  500  that the image forming apparatus  1  according to the present embodiment has. 
     The exposing unit  500  in  FIG. 3  has the optical print head  105  and a movement mechanism  640 . The optical print head  105  is provided with a lens array  506 , a circuit board  502  (omitted from illustration in  FIG. 3 ), a holding member  505 , a first abutting pin  514 , and a second abutting pin  515 . 
     A gap is formed between the lens array  506  and the photosensitive drum  103  by the first abutting pin  514  and the second abutting pin  515  coming into contact with the drum unit  518 , and the position of the optical print head  105  as to the photosensitive drum  103 , when forming images, is determined. The movement mechanism  640  has a first link mechanism  861 , a second link mechanism  862 , and a sliding portion  525  (an example of a moving member). The first link mechanism  861  has a link member  651  and link member  653 . The second link mechanism  862  has a link member  652  and link member  654 . The sliding portion  525  moves by sliding in the front-and-rear directions, in conjunction with opening/closing operations of the cover  558  that is omitted from illustration in  FIG. 3 . The first link mechanism  861  and second link mechanism  862  are driven synchronously with the sliding movement of the sliding portion  525 , and the optical print head  105  moves up and down. Detailed operations of the movement mechanism  640  will be described later. The portions of the frame of the drum unit  518  where the first abutting pin  514  and second abutting pin  515  abut are provided with fitting holes where the tips of the first abutting pin  514  and second abutting pin  515  fit in by around 5 mm, for example. Thus, the optical print head  105  is accurately positioned as to the photosensitive drum  103 . 
     The holding member  505  will be described next in the description of the structure of the optical print head  105 . The holding member  505  is a holder that holds the later-described circuit board  502  and lens array  506 . Resin is employed as the material for the holding member  505  in the present embodiment, from the perspective of reducing weight and reducing costs of the optical print head  105  itself, but may be metal instead. 
     The exposing unit  500  is disposed below the rotational axis of the photosensitive drum  103  in the vertical direction, and the LEDs  503  that the optical print head  105  has expose the photosensitive drum  103  from beneath. Note that a configuration may be made where the exposing unit  500  is disposed above the rotational axis of the photosensitive drum  103  in the vertical direction, and the LEDs  503  that the optical print head  105  has expose the photosensitive drum  103  from above. 
     Next, the circuit board  502  held by the holding member  505  will be described.  FIG. 4A  is a schematic perspective view of the circuit board  502 . FIG.  4 B 1  illustrates the array of the multiple LEDs  503  provided on the circuit board  502 . FIG.  4 B 2  is an enlarged view of FIG.  4 B 1 . 
     LED chips  639  are mounted on the circuit board  502 . The LED chips  639  are mounted on one face of the circuit board  502 , while a connector  504  is provided to the other face, as illustrated in  FIG. 4A . The circuit board  502  is provided with wiring to supply signals to the LED chips  639 . One end of a flexible flat cable (FFC) that is omitted from illustration is connected to the connector  504 . A circuit board is provided to the main body of the image forming apparatus  1 . The circuit board has a control unit and connector. The other end of the FFC is connected to this connector. Control signals are input to the circuit board  502  from the control unit of the main body of the image forming apparatus  1  via the FFC and connector  504 . The LED chips  639  are driven by the control signals input to the circuit board  502 . 
     The LED chips  639  mounted on the circuit board  502  will be described in further detail. Multiple ( 29 ) LED chips  639 - 1  through  639 - 29  are arrayed on one face of the circuit board  502 , as illustrated in FIGS.  4 B 1  and  4 B 2 . Each of the LED chips  639 - 1  through  639 - 29  has multiple LEDs that are examples of light-emitting elements arrayed in a single row in the longitudinal direction thereof. Each of the LED chips  639 - 1  through  639 - 29  has 516 LEDs. The center-to-center distance k 2  between LEDs adjacent in the longitudinal direction in the LED chips  639  corresponds to the resolution of the image forming apparatus  1 . The resolution of the image forming apparatus  1  according to the present embodiment is 1200 dpi, so the LEDs are arrayed in a single row so that the center-to-center distance k 2  between adjacent LEDs in the longitudinal direction of the LED chips  639 - 1  through  639 - 29  is 21.16 μm. Accordingly, the range of exposure of the optical print head  105  according to the present embodiment is approximately 316 mm. The photosensitive layer of the photosensitive drum  103  is formed to be 316 mm or wider. The length of the long side of an A4-size recording sheet and the length of the short side of an A3-size recording sheet are 297 mm, so the optical print head  105  according to the present embodiment has an exposing range that executes forming images on A4-size recording sheets and A3-size recording sheets. 
     The LED chips  639 - 1  through  639 - 29  are alternately arrayed to form two rows in the rotational axis direction of the photosensitive drum  103 . That is to say, odd-numbered LED chips  639 - 1 ,  639 - 3 , and so on through  639 - 29 , are arrayed on one line in the longitudinal direction of the circuit board  502  from the left, and even-numbered LED chips  639 - 2 ,  639 - 4 , and so on through  639 - 28 , are arrayed on one line in the longitudinal direction of the circuit board  502 , as illustrated in FIG.  4 B 1 . Arraying the LED chips  639  in this way allows the center-to-center distance k 1  between the LEDs disposed on one end of one LED chip  639  and the other end of another LED chip  639  among different adjacent LED chips  639  to be equal to the center-to-center distance k 2  of adjacent LEDs on the same LED chip  639 , in the longitudinal direction of the LED chips  639 , as illustrated in FIG.  4 B 2 . An example where the exposing light source is configured using LEDs is described in the present embodiment. However, OLEDs may be used instead as the exposing light source. 
     Next, the lens array  506  will be described. FIG.  4 C 1  is a schematic diagram viewing the lens array  506  from the photosensitive drum  103  side. FIG.  4 C 2  is a schematic perspective view of the lens array  506 . These multiple lenses are arrayed in two rows following the direction of array of the multiple LEDs  503 , as illustrated in FIG.  4 C 1 . The lenses are disposed in a staggered manner such that each lens in one row comes into contact with two lenses in the other row that are adjacent in the direction of array of the lenses. The lenses are cylindrical glass rod lenses. Note that the material of the lenses is not restricted to glass, and that plastic may be used. The shape of the lenses is not restricted to a cylindrical shape either, and may be polygonal posts such as hexagonal posts or the like, for example. 
     A dotted line Z in FIG.  4 C 2  indicates the optical axis of a lens. The optical print head  105  is moved by the above-described movement mechanism  640  in a direction generally following the optical axis of the lens indicated by the dotted line Z. The term optical axis of a lens here means a line that connects the center of the light emitting face of the lens and the focal point of this lens. The discharged light emitted from an LED enters a lens included in the lens array  506 . The lens functions to condense the discharged light entering the lens onto the surface of the photosensitive drum  103 . The attachment position of the lens array  506  as to a lens attaching portion, omitted from illustration, is adjusted when assembling the optical print head  105 , such that the distance between the light-emitting face of the LED and incoming light face of the lens, and the distance between the light-emitting face of the lens and the surface of the photosensitive drum  103 , are generally equal. 
     Movement Mechanism 
     The movement mechanism  640  that moves the optical print head  105  between the exposing position and the retracted position will be described. The movement mechanism  640  reciprocally moves the optical print head  105  between the exposing position and the retracted position, which will be described below. The movement mechanism  640  has the first link mechanism  861 , the second link mechanism  862 , the sliding portion  525 , and a first support portion  526 , as illustrated in  FIG. 3 . The first link mechanism  861  includes the link member  651  and link member  653 , and the second link mechanism  862  includes the link member  652  and link member  654 . The link member  651  and link member  653 , and the link member  652  and link member  654 , each make up a λ-type link mechanism, as illustrated in  FIG. 3 . 
       FIG. 5A  is a schematic perspective view of the front side of the movement mechanism  640 , as viewed from the left side.  FIG. 5B  is a schematic perspective view of the front side of the movement mechanism  640 , as viewed from the right side. 
     The first link mechanism  861  will be described with reference to  FIGS. 5A through 6B .  FIG. 6A  is a diagram where a cross-sectional view of the first link mechanism  861  taken along the rotational axis of the photosensitive drum  103  is viewed from the right side. The first link mechanism  861  has the link member  651  and link member  653 . The link member  651  and link member  653  making up the first link mechanism  861  are each single link members, but may be configured by combining multiple link members. The length of the link member  653  in the longitudinal direction is shorter than the length of the link member  651  in the longitudinal direction, as illustrated in  FIGS. 6A and 6B . 
     The link member  651  has a bearing  610 , a protrusion  655 , and a connecting shaft portion  538 . The bearing  610  is provided to one end side in the longitudinal direction of the link member  651 . The protrusion  655  is a cylindrical protrusion erected in the pivoting axis direction of the link member  651  provided at the other end side in the longitudinal direction of the link member  651 , for causing deformation of a spring provided to the holding member  505  side of the optical print head  105 . The connecting shaft portion  538  is provided between the bearing  610  and protrusion  655  in the longitudinal direction of the link member  651 . Although the protrusion  655  serves as a first moving portion, the first moving portion is not restricted to the protrusion  655 , and may be a structure where one end side in the longitudinal direction of the link member  651  is bent in the pivoting axis direction. 
     A circular hollowed space that extends in the left-and-right direction in  FIG. 6A  is formed in the bearing  610 , as a hole. A fitting shaft portion  534  is provided to the sliding portion  525 . The fitting shaft portion  534  is a cylindrical protrusion erected from the sliding portion  525  to the left direction in  FIG. 6A . The fitting shaft portion  534  forms a first connecting portion by being pivotably fit to the hole of the bearing  610 . That is to say, the link member  651  is configured to pivot as to the sliding portion  525 , with the first connecting portion as the center of pivoting. Note that the fitting shaft portion  534  may be formed on the link member  651  side, and the bearing  610  formed on the sliding portion  525 . 
     The link member  653  has a connecting shaft portion  530 . The connecting shaft portion  530  is provided to one end side in the longitudinal direction of the link member  653 . The connecting shaft portion  530  is a cylindrical protrusion erected from the link member  653  to the left side in  FIG. 6A . The connecting shaft portion  530  is rotatably inserted into a hole formed in the first support portion  526 , and thus forms a third connecting portion. Now, the connecting shaft portion  530  may be formed to the first support portion  526  rather than the link member  653 . That is to say, the connecting shaft portion  530  formed on the first support portion  526  may be inserted to a hole formed in the link member  653 . 
     A circular hole that extends in the left-and-right direction in  FIG. 6A  is formed at the other end side in the longitudinal direction of the link member  653 . The connecting shaft portion  538  of the link member  651  is pivotably inserted into this hole, whereby the connecting shaft portion  538  and the hole of the link member  653  make up of a fourth connecting portion. That is to say, the link member  653  is configured to pivot as to the first support portion  526  with the third connecting portion as a center of pivoting, and is configured to pivot as to the link member  651  with the fourth connecting portion as a center of pivoting. Now, the connecting shaft portion  538  may be formed on the link member  653  rather than the link member  651 . That is to say, the connecting shaft portion  538  formed on the link member  653  may be inserted into a hole formed in the link member  651 . 
     Note that the configuration of the second link mechanism  862  is the same as the configuration of the first link mechanism  861  described above. The link member  652  and link member  654  that the second link mechanism  862  has correspond to the link member  651  and link member  653 , respectively. The one end side in the longitudinal direction of the link member  652  and the connecting portion of the sliding portion  525  make up a second connecting portion, corresponding to the first connecting portion. Note that one of the link member  653  and link member  654  may be omitted from the embodiment regarding the movement mechanism  640 . 
     According to the above configuration, when the sliding portion  525  moves by sliding from the front side toward the rear side with regard to the first support portion  526 , the bearing  610  to which the fitting shaft portion  534  has been fit moves by sliding from the front side toward the rear side as to the first support portion  526 , along with the sliding portion  525 . Accordingly, when viewing the first link mechanism  861  from the right side as illustrated in  FIG. 6A , the link member  651  pivots in the clockwise direction with the fitting shaft portion  534  as the center of pivoting, and the link member  653  pivots in the counter-clockwise direction with the connecting shaft portion  530  as the center of pivoting. Accordingly, the protrusion  655  moves in a direction from the exposing position toward the retracted position. 
     On the other hand, when the sliding portion  525  moves by sliding from the rear side toward the front side as to the first support portion  526 , the link member  651  and link member  653  move in the opposite directions as to the arrows in  FIG. 6A . When the sliding portion  525  moves by sliding from the rear side toward the front side with regard to the first support portion  526 , the bearing  610  to which the fitting shaft portion  534  has been fit moves by sliding from the rear side toward the front side as to the first support portion  526 , along with the sliding portion  525 . Accordingly, when viewing the first link mechanism  861  from the right side as illustrated in  FIG. 6A , the link member  651  pivots in the counter-clockwise direction with the fitting shaft portion  534  as the center of pivoting, and the link member  653  pivots in the clockwise direction with the connecting shaft portion  530  as the center of pivoting. Accordingly, the protrusion  655  moves in a direction from the retracted position toward the exposing position. 
     Now, 
     (1) the distance between the pivoting center axis of the connecting shaft portion  538  and the pivoting center axis of the bearing  610  will be referred to as L 1 , 
     (2) the distance between the pivoting center axis of the connecting shaft portion  538  and the pivoting center axis of the connecting shaft portion  530  will be referred to as L 2 , and 
     (3) the distance between the pivoting center axis of the connecting shaft portion  538  and the pivoting center axis of the protrusion  655  will be referred to as L 3 . In the movement mechanism  640 , the first link mechanism  861  forms a Scott Russel linkage where L 1 , L 2 , and L 3  are equal (see  FIG. 6B ). The protrusion  655  moves perpendicular (along dotted line A in  FIG. 6B ) to the direction of sliding movement of the fitting shaft portion  534  due to the distances L 1 , L 2 , and L 3  being equal, so the optical print head  105  can be moved generally in the optical axis direction of the lens in the above-described link mechanism. 
     Now, a configuration may be made where the front-and-rear directions of the first link mechanism  861  and second link mechanism  862  are opposite, so that when the sliding portion  525  is moved by sliding from the front side toward the rear side, the optical print head  105  moves from the retracted position toward the exposing position, and when the sliding portion  525  is moved by sliding from the rear side toward the front side, the optical print head  105  moves from the exposing position toward the retracted position. In this case, the later-described cover  558  presses the sliding portion  525  from the front side toward the rear side when moving from an opened state to a closed state, and draws the sliding portion  525  out from the rear side toward the front side when moving from a closed state to an opened state. 
     The mechanism for moving optical print head  105  is not restricted to the movement mechanism  640 . A movement mechanism  140  illustrated in  FIGS. 7A and 7B  may be used. The movement mechanism  140  will be described below with reference to  FIGS. 7A through 8B . Note that members which have substantially the same functions as the members making up the movement mechanism  640  are denoted by the same reference numerals, and redundant description may be omitted. 
     The arrangement by which the movement mechanism  140  moves the holding member  505  will be described below with reference to  FIGS. 7A through 8B .  FIG. 8A  is a cross-sectional view of the holding member  505  and the movement mechanism  140  illustrated in  FIG. 8B , taken along the rotational axis of the photosensitive drum  103 . 
     The link member  151  has a bearing  110  and a protrusion  155 , as illustrated in  FIGS. 7A and 7B . The bearing  110  is provided at the one end side of the link member  151  in the longitudinal direction. The protrusion  155  is, as illustrated in  FIGS. 8A and 8B , a cylindrical protrusion that is provided on the other end side of the link member  151  in the longitudinal direction and that is erected in the pivoting axis direction of the link member  151 . The protrusion  155  is a protrusion for deforming a spring provided on the holding member  505  side of the optical print head  105 . Note that the first moving portion is not restricted to being the protrusion  155 , and may be a structure where the one end side in the longitudinal direction of the link member  151  is bent in the pivoting axis direction of the link member  151 . 
     A circular hollowed space that extends in the left-and-right direction is formed in the bearing  110 , as a hole. A fitting shaft portion  534  is provided to the sliding portion  525 , as illustrated in  FIGS. 8A and 8B . The fitting shaft portion  534  is a cylindrical protrusion erected from the sliding portion  525  toward the left. The hole of the bearing  110  is fit with the fitting shaft portion  534  so as to be configured to pivot, thereby forming a first connecting portion. That is to say, the link member  151  is pivotable as to the sliding portion  525 , with the first connecting portion as the center of pivoting. Note that an arrangement may be made where the fitting shaft portion  534  is formed on the link member  151  side, and the bearing  110  is formed on the sliding portion  525 . 
     Note that a shaft the same as the support shaft  531  is provided at the rear side of the first support portion  526 , a slot the same as the slot  691  is formed at the rear side of the sliding portion  525 , and the structure of the rear side of the movement mechanism  140  is the same as the front side. The structure of the link member  152  also is the same as the structure of the first moving member described above, with the link member  152  corresponding to the link member  151 . The connecting portion of the one end side in the longitudinal direction of the link member  152  and the sliding portion  525  make up the second connecting portion, corresponding to the first connecting portion. 
     The abutting portion  529  that faces the holding member  505  in the direction of sliding movement of the sliding portion  525  is disposed further toward the front side as compared to the one end of the holding member  505 . Accordingly, when the sliding portion  525  moves by sliding as to the first support portion  526  from the rear side to the front side, the bearing  110  to which the fitting shaft portion  534  is fit also moves by sliding as to the first support portion  526  from the rear side to the front side, along with the sliding portion  525 . The holding member  505  to which the protrusion  155  is attached also attempts to move toward the front side in conjunction with this, but the one end of the holding member  505  is abutting the abutting portion  529 , and accordingly movement toward the front side is restricted. The link member  151  is disposed intersecting the rotational axis direction of the photosensitive drum  103  such that the one end side having the protrusion  155  is situated closer to the drum unit  518  side as compared to the other end side having the bearing  110 , and accordingly pivots in a counter-clockwise direction with the fitting shaft portion  534  as the center of pivoting, as viewed from the right side as illustrated in  FIG. 8A . Accordingly, the holding member  505  moves from the retracted position toward the exposing position with the one end of the holding member  505  abutting the abutting portion  529 . 
     On the other hand, when the sliding portion  525  moves by sliding as to the first support portion  526  from the front side to the rear side, the bearing  110  fit to the fitting shaft portion  534  moves by sliding as to the first support portion  526  from the rear side to the front side, along with the sliding portion  525 . Accordingly, the link member  151  pivots in a clockwise direction with the fitting shaft portion  534  as the center of pivoting, as viewed from the right side as illustrated in  FIG. 8A . Thus, the protrusion  155  moves in a direction from the exposing position toward the retracted position. The sliding portion  525  moves from the rear side to the front side in conjunction with a closing operation of the cover  558 , and moves from the front side to the rear side in conjunction with an opening operation of the cover  558 , which will be described in detail later. That is to say, when the cover  558  moves from an opened state to a closed state, the holding member  505  moves in a direction from the retracted position toward the exposing position, and when the cover  558  moves from the closed state to the opened state, the holding member  505  moves in a direction from the exposing position toward the retracted position. 
     Note that the link member  151  and link member  152  may be arranged such that the other end side is situated further toward the front side than the one end side, with the abutting portion  529  situated further toward the rear side than the other end of the holding member  505 . That is to say, when the sliding portion  525  moves by sliding as to the first support portion  526  from the front side to the rear side, the bearing  110  to which the fitting shaft portion  534  is fit also moves by sliding as to the first support portion  526  from the front side to the rear side, along with the sliding portion  525 . The holding member  505  to which the protrusion  155  is attached also attempts to move to the rear side in conjunction with this, but the other end of the holding member  505  is abutting the abutting portion  529 , and accordingly movement toward the rear side is restricted. Accordingly, the link member  151  and link member  152  pivot in the clockwise direction as to the sliding portion  525  when viewing the link member  151  from the right side, and the holding member  505  moves from the retracted position toward the exposing position with the other end of the holding member  505  abutting the abutting portion  529 . In this case, the cover  558  presses the sliding portion  525  from the front side toward the rear side when moving from the opened state to the closed state, and draws the sliding portion  525  out from the rear side toward the front side when moving from the closed state to the opened state. 
     The mechanism for moving the optical print head  105  is not restricted to the movement mechanism  140  and movement mechanism  640 . A movement mechanism  840  illustrated in FIGS.  9 A 1  through  9 B may be used. The movement mechanism  840  will be described below with reference to FIGS.  9 A 1  through  9 B. Note that members having substantially the same functions as members making up the movement mechanism  140  ( 840 ) are described being denoted by the same reference numerals, and redundant description may be omitted. 
     FIGS.  9 A 1  and  9 A 2  illustrate the movement mechanism  840 . The movement mechanism  840  includes a first link mechanism  858 , a second link mechanism  859 , sliding portion  825 , and the first support portion  526 , as illustrated in FIGS.  9 A 1  and  9 A 2 . The first link mechanism  858  includes a link member  843  and a link member  844 , and the second link mechanism  859  includes a link member  845  and a link member  846 . The link member  843  and link member  844 , and the link member  845  and link member  846 , each pivotably intersect each other, making up an X-shaped link mechanism as illustrated in FIGS.  9 A 1  through  9 B. A protrusion  847  of the link member  843 , a protrusion  848  of the link member  844 , a protrusion  849  of the link member  845 , and a protrusion  850  of the link member  846 , are each pivotably attached to a holding member  805  that is omitted from illustration. When a sliding portion  825  is moved by sliding in the direction of the arrow A in FIG.  9 A 1 , the link members  843  through  846  pivot with regard to the sliding portion  825 , and the protrusions  847  through  850  move downwards (FIG.  9 A 2 ). On the other hand, when the sliding portion  825  is moved by sliding in the direction of the arrow B in FIG.  9 A 2 , the link members  843  through  846  pivot with regard to the sliding portion  825 , and the protrusions  847  through  850  move upwards (FIG.  9 A 1 ). 
       FIG. 9B  is a diagram illustrating the front side of the movement mechanism  840  with the front side of the holding member  805 . The arrangement by which the movement mechanism  840  moves the holding member  805  will be described below with reference to  FIG. 9B . Now, the operations of the first link mechanism  858  and second link mechanism  859  are substantially the same, so the first link mechanism  858  will be described here with reference to  FIG. 9B . The first link mechanism  858  has the link member  843  and link member  844 . The link member  843  and link member  844  making up the first link mechanism  858  are each single members, but may be configured by combining multiple link members. 
     The movement mechanism  840  in  FIG. 9B  has the first link mechanism  858  and sliding portion  825 . The sliding portion  825  has a slot  863  that is an elongated opening, passing through the sliding portion  825  in the left-and-right direction and extending in the front-and-rear direction, as illustrated in  FIG. 9B . 
     The link member  843  has a protrusion  810 , the protrusion  847 , and the connecting shaft portion  538 . The protrusion  810  is provided to one end side in the longitudinal direction of the link member  843 . The protrusion  847  is a cylindrical protrusion erected to the right side in the pivoting axial direction of the link member  843 , provided to the other end side in the longitudinal direction of the link member  843 . The connecting shaft portion  538  is provided between the protrusion  810  and protrusion  847  in the longitudinal direction of the link member  843 . Although the protrusion  847  serves as a first moving portion, the first moving portion is not restricted to the protrusion  847 , and may be a structure where one end side in the longitudinal direction of the link member  843  is bent in the pivoting axis direction. 
     The protrusion  810  is pivotably loosely fit to the slot  863  of the sliding portion  825 , thereby forming the first connecting portion. That is to say, the link member  843  is pivotable as to the sliding portion  825  with the first connecting portion as the center of pivoting. The protrusion  810  also is configured to move in the front-and-rear direction within the range of the slot  863  in the front-and-rear direction (within the opening). A coil spring  860  is disposed between the rear-side edge of the slot  863  and the protrusion  810 . 
     The link member  844  has the connecting shaft portion  530  and the protrusion  848 . The connecting shaft portion  530  is provided to one end side in the longitudinal direction of the link member  844 . The connecting shaft portion  530  is a cylindrical protrusion erected from the link member  844  to the right side in  FIG. 9B . The connecting shaft portion  530  is pivotably inserted into a hole formed in the first support portion  526 , thereby forming the third connecting portion. Now, the connecting shaft portion  530  may be formed on the first support portion  526  rather than the link member  844 . That is to say, the connecting shaft portion  530  formed on the first support portion  526  may be inserted into a hole formed in the link member  844 . 
     The protrusion  848  is a cylindrical protrusion provided to the other end side in the longitudinal direction of the link member  844 , erected to the right side in the pivoting axis direction of the link member  844 . A circular hole that extends in the left-and-right direction in  FIG. 9B  is formed between the protrusion  848  of the link member  844  and the third connecting portion. The connecting shaft portion  538  of the link member  843  is pivotably inserted into this hole, whereby the connecting shaft portion  538  and the hole of the link member  844  make up the fourth connecting portion. That is to say, the link member  844  is configured to pivot as to the first support portion  526  with the third connecting portion as a center of pivoting, and is configured to pivot as to the link member  843  with the fourth connecting portion as a center of pivoting. Now, the connecting shaft portion  538  may be formed on the link member  844  rather than the link member  843 . That is to say, the connecting shaft portion  538  formed on the link member  844  may be inserted into a hole formed in the link member  843 . Note that one of the link member  843  and link member  844  may be omitted from the embodiment regarding the movement mechanism  840 . 
     The holding member  805  has the lens array  506 , a link attaching portion  851 , a link attaching portion  852 , and a pin attaching portion  855 . The link attaching portion  851  and link attaching portion  852  both are provided between pins  514  attached to the lens array  506  and holding member  805 . Although omitted from illustration, a link attaching portion  853  and link attaching portion  854  to which the link member  845  and link member  846  making up the second link mechanism  859  are attached are both provided between pins  515  attached to the other end side of the lens array  506  and holding member  805 . The link attaching portion  851  is a hole formed to the holding member  805  between the lens array  506  and pin attaching portion  855 , passing through in the left-and-right direction. The link attaching portion  852  is a slot that is formed in the holding member  805  between the lens array  506  and the link attaching portion  851 , and that passes through in the left-and-right direction and extends in the front-and-rear direction. 
     The protrusion  847  of the link member  843  is pivotably attached to the link attaching portion  851 , and the protrusion  848  of the link member  844  is pivotably attached to the link attaching portion  852 . The protrusion  848  is attached to the link attaching portion  851  so as to be configured to move in the front-and-rear direction. Accordingly, the link member  844  is configured to move by sliding in the front-and-rear direction within the range of the link attaching portion  852  in the front-and-rear direction, while pivoting with the protrusion  848  as a center of pivoting. 
     According to the above-described configuration, when the sliding portion  825  moves by sliding from the front side to the rear side as to the first support portion  526 , the protrusion  810  moves by sliding from the front side to the rear side as to the first support portion  526  along with the sliding portion  825 . Accordingly, when viewing the first link mechanism  858  from the right side as illustrated in FIG.  9 A 1 , the protrusion  848  moves from the front side to the rear side at the link attaching portion  852  with the link member  843  pivoting clockwise with the protrusion  810  as the center of pivoting and the link member  844  pivoting counter-clockwise with the connecting shaft portion  530  as the center of pivoting. Accordingly, the protrusion  847  and protrusion  848  move in the direction from the exposing position toward the retracted position. 
     On the other hand, when the sliding portion  825  moves by sliding from the rear side to the front side as to the first support portion  526 , the protrusion  810  moves by sliding from the rear side to the front side as to the first support portion  526  along with the sliding portion  825 . Accordingly, when viewing the first link mechanism  858  from the right side as illustrated in FIG.  9 A 2 , the protrusion  848  moves from the rear side to the front side at the link attaching portion  852  with the link member  843  pivoting counter-clockwise with the protrusion  810  as the center of pivoting and the link member  844  pivoting clockwise with the connecting shaft portion  530  as the center of pivoting. Accordingly, the protrusion  847  and protrusion  848  move from the retracted position toward the exposing position. When the sliding portion  825  further moves by sliding to the front side in a state where the abutting pin  514  is in contact with an abutting face  550 , as illustrated in  FIG. 9B , the coil spring  860  is compressed between the rear side edge of the slot  863  and the protrusion  810 . The protrusion  810  is biased to the front side by the restoration force of the compressed coil spring  860 . Accordingly, biasing force heading upwards is applied to the holding member  805 . 
     Now, a configuration may be made where the front-and-rear directions of the first link mechanism  858  and second link mechanism  859  are opposite, so that when the sliding portion  825  is moved by sliding from the front side toward the rear side, the optical print head  105  moves from the retracted position toward the exposing position, and when the sliding portion  825  is moved by sliding from the rear side toward the front side, the optical print head  105  moves from the exposing position toward the retracted position. In this case, the later-described cover  558  presses the sliding portion  825  from the front side toward the rear side when moving from an opened state to a closed state, and draws the sliding portion  825  out from the rear side toward the front side when moving from a closed state to an opened state. 
     The mechanism for moving the optical print head  105  is not restricted to the movement mechanism  140 , movement mechanism  640 , and movement mechanism  840 . A movement mechanism  940  illustrated in  FIGS. 10A and 10B  may be used. The movement mechanism  940  will be described below with reference to  FIGS. 10A and 10B . Note that members having substantially the same functions as members making up the movement mechanism  140  (including  640  and  840 ) are described being denoted by the same reference numerals, and redundant description may be omitted. 
     As illustrated in  FIGS. 10A and 10B , a first cam portion  112  and a second cam portion  113  are provided to the front side and rear side of the sliding portion  525 . A movement support portion  114  and a movement support portion  115  are provided to the front side and rear side at the lower side of the holding member  905 . The first cam portion  112  and second cam portion  113  have a face inclined downwards from the rear side toward the front side as to the holding member  905  side. 
       FIG. 10A  is a schematic diagram illustrating the optical print head  105  situated at the exposing position and the movement mechanism  940 , as viewed from the right side. When the sliding portion  525  moves by sliding from the front side to the rear side as to the first support portion  526  in a case where the optical print head  105  is at the exposing position, the first cam portion  112  and second cam portion  113  provided to the sliding portion  525  move by sliding from the front side to the rear side as to the first support portion  526 , along with the sliding portion  525 . Accordingly, the lower ends of the movement support portion  114  and movement support portion  115  provided to the holding member  905  abut the first cam portion  112  and second cam portion  113 , and the movement support portion  114  and movement support portion  115  move along the first cam portion  112  and second cam portion  113  in a direction from the exposing position toward the retracted position. 
       FIG. 10B  is a schematic diagram illustrating the optical print head  105  situated at the retracted position and the movement mechanism  940 , as viewed from the right side. When the sliding portion  525  moves by sliding from the rear side to the front side as to the first support portion  526  in a case where the optical print head  105  is at the retracted position, the first cam portion  112  and second cam portion  113  provided to the sliding portion  525  move by sliding from the rear side to the front side as to the first support portion  526 , along with the sliding portion  525 . Accordingly, the lower ends of the movement support portion  114  and movement support portion  115  provided to the holding member  905  are pressed upwards and move along the first cam portion  112  and second cam portion  113  in a direction from the retracted position toward the exposing position. 
     Now a structure may be made where the direction of inclination of the inclined faces that the first cam portion  112  and second cam portion  113  respectively have is a downwards inclination from the front side toward the rear side, with sliding movement of the sliding portion  525  from the front side to the rear side moving the optical print head  105  from the retracted position toward the exposing position, and sliding movement of the sliding portion  525  from the rear side to the front side moving the optical print head  105  from the exposing position toward the retracted position. In this case, the later-described cover  558  presses the sliding portion  525  from the front side toward the rear side when moving from an opened state to a closed state, and draws the sliding portion  525  out from the rear side toward the front side when moving from a closed state to an opened state. 
       FIG. 11  is a diagram for describing an opening  161  formed in the first support portion  526  (example of a support portion). The opening  161  that is a through hole passing through the first support portion  526  is formed in the first support portion  526 , as described earlier. The opening  161  is formed in the bottom face, which is the face of the first support portion  526  that is at the lower side in the vertical direction in a state where the first support portion  526  is attached to the image forming apparatus  1 . The opening  161  also is formed in the part of the first support portion  526  that faces the connector  504  of the circuit board  502 . In further detail, the opening  161  is formed in the first support portion  526  so as to overlap the connector  504  in the direction of movement of the moving optical print head  105  between the exposing position and the retracted position by the movement mechanism  640 . That is to say, in a state where the optical print head  105  is mounted to the apparatus main body of the image forming apparatus  1 , the opening  161  formed on the first support portion  526  is situated below the connector  504  in the vertical direction. The opening  161  is a rectangular hole in the present embodiment, with the long side thereof being 70 mm long, and the short side 10 mm long. A cable  555  connected to the connector  504  of the circuit board  502  that the optical print head  105  has is passed through the opening  161 . The cable  555  extends from the connector  504  in the opposite direction from the side of the optical print head  105  where the photosensitive drum is situated, and passes through the opening  161 . 
     Mounting/Detaching Configuration of Optical Print Head as to Image Forming Apparatus Main Body 
       FIG. 12  is a diagram for describing a state where the first support portion  526  has been drawn out from the main body of the image forming apparatus  1  along with the optical print head  105 , by a worker such as a user, service staff, or the like. The first support portion  526  can be drawn out from the main body of the image forming apparatus  1  by sliding movement in the rotational axis direction of the photosensitive drum  103 , as illustrated in  FIG. 12 . When the worker draws the first support portion  526  out from the main body of the image forming apparatus  1 , the worker moves the first support portion  526  in the direction of the arrow A. On the other hand, when the worker mounts the first support portion  526  to the main body of the image forming apparatus  1 , the worker moves the first support portion  526  in the direction of the arrow B. Note that the “direction of arrow A” matches the “direction of drawing out” the first support portion  526  from the main body of the image forming apparatus  1 . The first support portion  526  moves in the direction of the arrow A and the direction of the arrow B via an opening  2010  formed in the front-side plate  642 . Now, a position where the first support portion  526  has been mounted to the main body of the image forming apparatus  1  in order to perform exposure of the photosensitive drum  103  will be defined as a mounted position, and a position where the first support portion  526  moves in the direction of the arrow A from the mounted position so that the connector  504  is situated at the downstream side from the opening  2010  in the direction of the arrow A will be defined as a drawn-out position. In a case where there is a need to remove the optical print head  105  from the main body of the image forming apparatus  1  in order to replace the circuit board  502  or the like, the worker moves the first support portion  526  to the drawn-out position, and operates the connector  504  to remove the cable  555  from the connector  504 . Thereafter, the first support portion  526  is further drawn out in the direction of the arrow A, whereby the first support portion  526  and optical print head  105  can be removed from the main body of the image forming apparatus  1 . 
     Next, a second support portion  1056  (an example of a guide portion) will be described with reference to  FIG. 12 . One end side of the second support portion  1056  (the front side of the main body of the image forming apparatus  1 ) is fixed to the front-side plate  642  by screws or the like. The other end side of the second support portion  1056  (the rear side of the main body of the image forming apparatus  1 ) is fixed to the rear-side plate  643  by screws or the like. The second support portion  1056  has a function of guiding movement of the first support portion  526  inserted into the main body of the image forming apparatus  1  from outside of the main body of the image forming apparatus  1  via the opening  2010  formed on the front-side plate  642 . In other words, the second support portion  1056  has a function of guiding movement of the first support portion  526  moving from the drawn-out position toward the mounted position or from the mounted position toward the drawn-out position. The first support portion  526  is supported from beneath in the vertical direction by the second support portion  1056  while partway through being moved from the drawn-out position (or mounted position) toward the mounted position (or drawn-out position) by a worker. Now, the first support portion  526  at the mounted position is positioned and supported only by the front-side plate  642  and rear-side plate  643  in the present embodiment. Accordingly, the first support portion  526  at the mounted position is not supported by the second support portion  1056 . The reason thereof is for the first support portion  526  to be positioned as to the photosensitive drum  103  with higher accuracy. If the first support portion  526  is positioned as to the second support portion  1056  fixed to the front-side plate  642  and rear-side plate  643 , the first support portion  526  will be positioned by the front-side plate  642  and rear-side plate  643  with one extra member (the second support portion  1056  in this case) therebetween. Note that the second support portion  1056  is disposed within the main body of the image forming apparatus  1  for each of the four image forming units  102 Y,  102 M,  102 C, and  102 K. However, part of the first support portion  526  may be in contact with the second support portion  1056  when in a positioned state in the apparatus main body of the image forming apparatus  1  with the optical print head  105  in the mounted position. 
     Further, the second support portion  1056  has a guide portion  1058  and a guide portion  1059 , as illustrated in  FIG. 12 . The guide portion  1058  has a function of guiding movement of the drum unit  518  (see  FIGS. 2A and 2B ) inserted through the opening  2010  of the front-side plate  642  toward the inside of the main body of the image forming apparatus  1 . The shape of the guide portion  1058  corresponds to that of the lower portion of the drum unit  518 . Accordingly, the drum unit  518  inserted from the front side of the main body of the image forming apparatus  1  through the opening  2010  of the front-side plate  642  toward the rear side fits to the guide portion  1058  with a slight amount of play. The worker further pushes the drum unit  518  in from the front side of the main body of the image forming apparatus  1  toward the rear side, in the state where the lower portion of the drum unit  518  is fit to the guide portion  1058 . The drum unit  518  thus moves along the guide portion  1058  from the front side of the main body of the image forming apparatus  1  toward the rear side, and is mounted to the main body of the image forming apparatus  1 . 
     On the other hand, the guide portion  1059  has a function of guiding movement of the optical print head  105  inserted through the opening  2010  of the front-side plate  642  toward the inside of the main body of the image forming apparatus  1 . In a case where there is operation failure or the like of the circuit board  502 , the optical print head  105  may be exchanged or repaired in maintenance. Accordingly, the optical print head  105  may have a configuration allowing replacement thereof in the image forming apparatus  1 . 
     The shape of the guide portion  1059  corresponds to that of the lower portion of the first support portion  526 . Accordingly, the first support portion  526  inserted from the front side of the main body of the image forming apparatus  1  through the opening  2010  of the front-side plate  642  toward the rear side fits to the guide portion  1059  with a slight amount of play. The first support portion  526  is further pushed in from the front side of the main body of the image forming apparatus  1  toward the rear side by the worker, in the state where the lower portion of the first support portion  526  is fit to the guide portion  1059 . The first support portion  526  thus moves along the guide portion  1059  from the front side of the main body of the image forming apparatus  1  toward the rear side, and fits to an opening that is omitted from illustration, formed in the rear-side plate  643  at the rear side end of the first support portion  526 . That is to say, the first support portion  526  can be positioned to the main body of the image forming apparatus  1  in a sure manner, by the worker moving the optical print head  105  from the front side of the main body of the image forming apparatus  1  toward the rear side in a state of being fit to the guide portion  1059 . 
     Next, the functions of a restricting portion  1062  (an example of a holding portion) provided to the lower side of the second support portion  1056  will be described. The restricting portion  1062  has a first wall portion  1062   a  and a second wall portion  1062   b , as illustrated in  FIG. 12 . The first wall portion  1062   a  is a member that holds the cable  555 , laid from above the second support portion  1056  toward the lower side of the second support portion  1056  via a hole  1056   a , by nipping the front side and rear side of the cable  555  between the first wall portion  1062   a  and second wall portion  1062   b . Thus restricting portion  1062  is provided at the downstream side from a later-described protruding portion  662  in the direction in which the first support portion  526  is drawn out, in a state where the first support portion  526  is at the mounted position. The cable  555  is in a state attached to the second support portion  1056  by being nipped between the first wall portion  1062   a  and second wall portion  1062   b . The first wall portion  1062   a  has elasticity, and the tip (the portion that comes into contact with the cable  555 ) side thereof is constantly pressed against the second wall portion  1062   b . Accordingly, the cable  555  is nipped between the first wall portion  1062   a  and second wall portion  1062   b  in the rotational axis direction of the photosensitive drum  103 , and movement from the front side of the image forming apparatus  1  toward the rear side, and movement from the rear side of the image forming apparatus  1  toward the front side, is restricted. Note that the configuration of the restricting portion  1062  is not restricted to a configuration such as described above, and may be of a configuration where the second wall portion  1062   b  has elasticity, i.e., a configuration where the second wall portion  1062   b  is pressed against the first wall portion  1062   a , or a configuration where both are pressed against each other. Also, a configuration may be made where the second wall portion  1062   b  is omitted, for example, and the first wall portion  1062   a  is pressed against the lower side of the second support portion  1056 . In this case, the cable  555  is attached to the second support portion  1056  by being nipped between the first wall portion  1062   a  and second support portion  1056  in the vertical direction. The cable  555  in the present embodiment is nipped between the first wall portion  1062   a  and second wall portion  1062   b , but is configured to move in the nipped state. It is sufficient for the functions of the restricting portion  1062  to be such that movement of part of the cable  555  from the rear side of the image forming apparatus  1  toward the front side is restricted. Accordingly, the cable  555  may be fixed to the restricting portion  1062  by adhesive agent, double-sided adhesive tape, or the like, with slight movement (several centimeters) allowed. 
     The restricting portion  1062  does not have to be provided to the second support portion  1056 . It is sufficient for the restricting portion  1062  to be disposed further to the rear side of the image forming apparatus  1  from the front-side plate  642  and further to the front side of the image forming apparatus  1  from the rear-side plate  643 . Examples of positions where the restricting portion  1062  can be disposed include the rear side of the front-side plate  642  and the front side of the rear-side plate  643 , for example. In a case of placing a relay board connected to the other end side of the cable  555  further to the rear side of the image forming apparatus  1  from the rear-side plate  643 , the cable  555  extending from the relay board passes through a hole formed in the rear-side plate  643  and is laid at the front side from the rear-side plate  643 . Note that the relay board mentioned here has functions of relaying drive signals sent from the control unit to the circuit board  502  in order to control drive voltage for driving the LEDs  503 . The other end of the cable  555  may be directly connected to the control unit that is omitted from illustration, instead of the relay board. The cable  555  extending toward the front side from the hole formed in the rear-side plate  643  is connected to the connector  504  of the circuit board  502  via the hole  1056   a  formed in the second support portion  1056 . 
       FIG. 13  is a schematic perspective view illustrating a state where the first support portion  526  is at the mounted position. The restricting portion  1062  is omitted from illustration. Note that the cable  555 , electrically connected to the control unit that is omitted from illustration and the connector  504 , is passed through the hole  1056   a  formed in the second support portion  1056 . The hole  1056   a  will be described in detail later. Routing of the cable  555  will be described with reference to  FIG. 13 . The cable  555  connected to the connector  504  passes through the opening  161  that is omitted from illustration in  FIG. 13  formed in the first support portion  526 , and extends downwards in the vertical direction from the connector  504 . The cable  555  further extends from the opening  161  that is omitted from illustration in  FIG. 13  toward the rear side of the image forming apparatus  1  following the longitudinal direction of the first support portion  526  (rotational axis direction of the photosensitive drum  103 ), and is folded back at a portion shown in a region D. Accordingly, one region of the cable  555  is curved, and a curved region (region D) is formed in the cable  555 . The cable  555  that has been folded back at the region D extends following the guide portion  1059  of the second support portion  1056 , toward the restricting portion  1062  formed to the front side of the second support portion  1056 . The cable  555  is in contact with the first support portion  526  and the guide portion  1059  of the second support portion  1056  at the region D that is the curved region where the cable  555  is curved (hereinafter referred to as “curved portion D (one region of the cable)” formed in the cable  555 ). 
       FIG. 14  is a diagram for describing a state of the first support portion  526  moving from the mounted position to the drawn-out position. The restricting portion  1062  in  FIG. 12  has been omitted from illustration in  FIG. 14 , to simplify description here. The curved portion D formed in the cable  555  moves in the direction of the arrow A, along with the first support portion  526  that moves in the direction of the arrow A, as illustrated in  FIG. 14 . The movement of the cable  555  is restricted by the restricting portion  1062  that is omitted from illustration in  FIG. 14 . That is to say, the cable  555  is flexed as illustrated in region D in  FIG. 14 , and accordingly the first support portion  526  can be drawn out in the direction of the arrow A. The curved portion D formed in the cable  555  curves toward the rear side of the image forming apparatus  1  in the rotational axis direction of the photosensitive drum  103 . A worker further moves the first support portion  526  in the direction of the arrow A from the state illustrated in  FIG. 14 , so as to be moved to the drawn-out position. 
       FIG. 15  is a diagram illustrating a state where the first support portion  526  has moved to the drawn-out position. When the first support portion  526  is at the drawn-out position, the connector  504  is situated at the front side from the opening  2010  of the front-side plate  642 , as illustrated in  FIG. 15 . The worker removes the cable  555  from the connector  504  in this state, and thereafter further draws the first support portion  526  out in the direction of the arrow A, and thus can remove the first support portion  526  and optical print head  105  from the image forming apparatus  1 . When the first support portion  526  is situated at the drawn-out position, the cable  555  is in contact with the edge of the hole  1056   a  and is bent. 
       FIGS. 16A and 16B  are diagrams for describing a cable guide portion  556  provided on the edge of the opening  161  of the first support portion  526 . The cable guide portion  556  is attached by a snap-fit structure to the opening  161  formed in a bottom face portion  665  of the first support portion  526 . The cable guide portion  556  has a first wall portion  660 , a second wall portion  661 , a protruding portion  662 , and a cover  663  (an example of an abutting portion), as illustrated in  FIG. 16A .  FIG. 16B  is a diagram illustrating a state in which the cover  663  of the cable guide portion  556  is open. The cable  555  that extends from the opening  161  to the lower side of the first support portion  526  is bent back at the portion of the opening  161 , as illustrated in  FIG. 16B . The cable  555  that has been bent back extends toward one end side or the other end side of the first support portion  526  in the direction of sliding movement of the sliding portion  525  omitted from illustration in  FIGS. 16A and 16B . Note that the cable  555  in the present embodiment is routed from the opening  161  to the other end side of the first support portion  526  (the rear side of the image forming apparatus  1 ) in the direction of sliding movement of the sliding portion  525  omitted from illustration in  FIGS. 16A and 16B . The portion of the cable  555  that has been bent is supported upwards in the vertical direction by the closed cover  663 , as illustrated in  FIG. 16A . In other words, the cover  663  is in contact with the bent portion of the cable  555  in the direction of the optical print head  105  moving from the retracted position to the exposing position. 
     The cable in the present embodiment is nipped between the closed cover  663  and the first support portion  526 . The cable  555  nipped between the cover  663  and the first support portion  526  is routed toward the opposite direction of the direction of drawing out the first support portion  526  (direction toward the rear side of the image forming apparatus  1 ), along the longitudinal direction of the first support portion  526 . 
       FIGS. 17A and 17B  are cross-sectional views of the exposing unit  500  taken in a direction perpendicular to the rotational axis direction of the photosensitive drum  103 .  FIG. 17A  illustrates a state where the optical print head  105  is at the exposing position, and  FIG. 17B  illustrates a state where the optical print head  105  is at the retracted position. 
     In  FIGS. 17A and 17B , the region indicated by a dashed line X indicates a region of the cable  555  between a portion connected to the connector  504  and a portion bent in contact with the cover  663 . The cable  555  is not flexed in the portion indicated by the dashed line X when the optical print head  105  is situated at the exposing position, as illustrated in  FIG. 17A . On the other hand, the cable  555  is flexed (or bent) in the portion indicated by the dashed line X when the optical print head  105  is situated at the retracted position, as illustrated in  FIG. 17B . This is because the cable  555  extending from the connector  504  is supported by the cover  663  in a state of being in contact with the cover  663 . Although the portion of the cable  555  indicated by the dashed line X moves in the vertical direction in conjunction with the optical print head  105  moving between the exposing position and the retracted position, the cable  555  is received by the cover  663 , as illustrated in  FIG. 17B . The portion of the cable  555  encircled by the dashed line X bends between the connector  504  and the cover  663 , and accordingly does not protrude to the lower side of the cable guide portion  556  in the vertical direction. 
     Now, a configuration where the cable guide portion  556  does not have the cover  663  will be assumed. In this case, when the optical print head  105  moves from the exposing position toward the retracted position as illustrated in  FIG. 17B , the cable  555  is not supported by the cover  663 , so no flexed portion is formed on the cable  555  such as indicated by the dashed line X, and the cable  555  is exposed downwards in the vertical direction from the opening  161  of the first support portion  526 . If a worker happens to perform insertion/extraction of the first support portion  526  via the opening  2010  of the front-side plate  642  in this state, the cable  555  exposed downwards in the vertical direction from the opening  161  of the first support portion  526  may come into contact with the edge of the opening  2010  of the front-side plate  642 . Providing the cover  663  as in the configuration of the present disclosure allows contact and damage of the cable  555  at the edge of the opening  2010  of the front-side plate  642  to be reduced. 
     The first wall portion  660  and second wall portion  661  of the cable guide portion  556  each protrude in a perpendicular direction from the bottom face portion  665  of the first support portion  526 . The protruding portion  662  is formed on the second wall portion  661  extending in a direction that is perpendicular to both the protruding direction of the second wall portion  661  and the longitudinal direction of the first support portion  526  (perpendicular direction). That is to say, the positional relation of each of the first wall portion  660 , second wall portion  661 , and protruding portion  662 , is that in a perpendicular direction perpendicular to both of the vertical direction and the rotational axis direction of the photosensitive drum  103 , the first wall portion  660  is at a position on one side of the protruding portion  662 , and the second wall portion  661  is situated on the other side of the protruding portion  662 . The protruding portion  662  is fixed to the first support portion  526  upstream from the opening  161  in the direction of drawing out the first support portion  526  (direction of arrow A). The cable  555  that is exposed from the opening  161  and is nipped between the cover  663  and the bottom face portion  665  of the first support portion  526  is routed between the first wall portion  660  and the second wall portion  661 . The first wall portion  660  and second wall portion  661  both overlap the cable  555  in a direction perpendicular to the direction in which the protruding portion  662  extends. The protruding portion  662  also is provided to the second wall portion  661  so as to be below the cable  555  routed between the first wall portion  660  and second wall portion  661 . That is to say, the cable  555  is supported by the protruding portion  662  from beneath in the vertical direction. In other words, the cable  555  is routed between the protruding portion  662  and the bottom face portion  665  of the first support portion  526  in the vertical direction. Note that the protruding portion  662  may be provided to the first wall portion  660  instead of the second wall portion  661 . In this case, the protruding portion  662  is a protrusion protruding from the first wall portion  660  toward the second wall portion  661 . The protruding portion  662  may also link the first wall portion  660  and second wall portion  661 . That is to say, the protruding portion  662  may be a member that connects the first wall portion  660  and second wall portion  661  in a perpendicular direction perpendicular to both the rotational axis direction of the photosensitive drum  103  and the vertical direction. 
     According to the above configuration, the cable  555  is routed from the opening  161  toward the rear side of the image forming apparatus  1 , due to part of the cable  555  being supported by the protruding portion  662  upstream from the opening  161  in the direction of the first support portion  526  being drawn out. 
     Also, the first wall portion  660  and second wall portion  661  protrude downwards in the vertical direction by a distance h from the protruding portion  662 , as indicated by the arrow h in  FIGS. 16A and 16B . The distance h is 5 mm in the present embodiment. This configuration can prevent the cable  555  from being caught between the protruding portion  662  and the lower-side edge of the opening  2010  formed in the front-side plate  642 , when the first support portion  526  is moved from the drawn-out position toward the mounted position, which will be described in detail later. 
     Further, an inclined face  666  is formed at the front side edge portion of the first wall portion  660 , and an inclined face  667  is formed at the front side edge portion of the second wall portion  661 , as illustrated in  FIG. 16A . The inclined face  666  and inclined face  667  are inclined toward the bottom face portion  665  of the first support portion  526  in accordance with the direction opposite to the direction of the first support portion  526  being drawn out from the image forming apparatus  1 . The angle of incline of the inclined face  666  as to the bottom face portion  665  and the angle of incline of the inclined face  667  as to the bottom face portion  665  each is 10 degrees or more but 40 degrees or less in the present embodiment. When the first support portion  526  passes through the opening  2010  from the drawn-out position toward the mounted position, the inclined face  666  and inclined face  667  abut the lower-side edge in the vertical direction of the opening  2010 . Thus, movement of the first support portion  526  is guided by the inclined face  666  and inclined face  667 . Accordingly, the worker can easily pass the first support portion  526  through the opening  2010  and move the first support portion  526  from the drawn-out position toward the mounted position. 
     Next, the length of the cable  555  between the hole  1056   a  and the connector  504 , and the distance between the hole  1056   a  and the opening  2010  of the front-side plate  642 , in a state where the first support portion  526  is mounted within the main body of the image forming apparatus  1  (a state of being situated at the mounted position) will be described with reference to  FIGS. 18A through 18C . 
       FIG. 18A  is a diagram for describing the cable  555  extending from the connector  504  to the hole  1056   a  formed in the second support portion  1056 . It can be seen from  FIG. 18A  that the cable  555  extending upward from the hole  1056   a  is routed toward the connector  504 . A region S 1  of the cable  555  is routed following the first support portion  526  toward the front side of the image forming apparatus  1 , and faces the lower face of the first support portion  526 . Note that the cable  555  extending toward the connector  504  is illustrated as having a configuration bent upwards at a generally right angle at the portion illustrated in a region S 2 , to simplify description. 
       FIG. 18B  illustrates a state where the bending (region S 2 ) of the cable  555  illustrated in  FIG. 18A  has been undone and straightened.  FIG. 18C  is a cross-sectional view of the front side of the second support portion  1056  and the opening  2010  of the front-side plate  642 , taken along the rotational axis direction of the photosensitive drum  103  in the vertical direction, in a state where the first support portion  526  is drawn out from the image forming apparatus  1 . A portion in  FIG. 18B  indicated by a dotted line  3100  is a portion of the cable  555  that comes into contact with the edge of the hole  1056   a  (wall portion  1060  or wall portion  1061 ). A portion in  FIG. 18B  indicated by a dotted line  3101  is a portion of the cable  555  that comes into contact with the restricting portion  1062 . The length of the portion indicated by arrow a in  FIG. 18B  indicates the length from the portion where the cable  555  extending downwards from the connector  504  is folded back toward the front side of the image forming apparatus  1 , to the portion where the cable  555  comes into contact with the edge of the hole  1056   a  (wall portion  1060 ). The length of the portion indicated by arrow a 2  in  FIG. 18B  indicates the length from the portion where the cable  555  comes into contact with the wall portion  1060  to the portion nipped by the restricting portion  1062 . The length of the arrow b in  FIG. 18B  is the length from the portion connected to the connector  504  to the portion where the cable  555 , extending downwards from the connector  504 , is folded back toward the front side of the image forming apparatus  1 . That is to say, the sum of the length of the cable  555  at the portion indicated by arrow a, which is the sum of arrow a 1  and arrow b 2 , and the length of the cable  555  at the portion indicated by arrow b, is the shortest length of the cable  555  from the restricting portion  1062  to the connector  504 . 
       FIG. 18C  illustrates a state where the cable  555  is folded back toward the front side of the image forming apparatus  1  with the wall portion  1060  of the hole  1056   a  as a fulcrum, due to the optical print head  105  having been drawn out from the image forming apparatus  1 . In this state, the cable  555  is taut and is not flexed. Now, the sum of length c, length d, and length e, which is the length of the cable  555  from the hole  1056   a  to the opening  2010 , is defined as the distance (shortest distance) between the hole  1056   a  and the opening  2010 , as illustrated in  FIG. 18C . This shortest distance can be found by pulling the connecting portion side (side connected to the connector  504 ) of the cable  555  toward the front side while in contact with the lower edge of the opening  2010 , even if the upper face of the second support portion  1056  has a stepped shape such as illustrated in the example in  FIG. 18C , for example. In other words, when the cable  555  is pulled from the rear side toward the front side, from the front side of the opening  2010  in a state where the cable  555  is nipped by the restricting portion  1062 , until there is no slack left, the distance from the restricting portion  1062  to the opening  2010  is the “shortest distance”. The length of the cable  555  from the restricting portion  1062  to the portion connected to the connector  504  is longer than the above-described “shortest distance”, as illustrated in  FIG. 12 . That is to say, the length of the cable  555  from the restricting portion  1062  to the portion connected to the connector  504  in a state where the cable  555  is connected to the connector  504 , is a length where the connector  504  is situated to the front side from the opening  2010  in a case where the optical print head  105  has been moved to the drawn-out position in a state with the cable  555  connected to the connector  504 . 
     By employing such a configuration, the worker can draw out the first support portion  526  to a drawn-out position that is a position where at least part of the connector  504  is situated at the front side of the image forming apparatus  1  from the opening  2010  of the front-side plate  642 . The worker moves the first support portion  526  to the drawn-out position and removes the cable  555  from the connector  504  that is situated to the front side from the opening  2010 . Thereafter, the worker further draws the optical print head  105  out toward the front side of the image forming apparatus  1 , and performs maintenance and the like of the optical print head  105 . 
     Second Embodiment 
       FIG. 19  is a diagram for describing a cable guide member  756  according to a second embodiment. The cable guide member  756  has a first wall portion  760 , a second wall portion  761 , and a contact face portion  763  (an example of an abutting portion), as illustrated in  FIG. 19 . The first wall portion  760  is provided on the bottom face of the first support portion  526  so as to be on one side of the opening  161 , in a perpendicular direction perpendicular to both of the rotational axis direction of the photosensitive drum  103  and the direction of movement of the optical print head  105  that is moved by the movement mechanism  640 . The second wall portion  761  is provided on the bottom face of the first support portion  526  so as to be on the other side of the opening  161 , in a perpendicular direction perpendicular to both of the rotational axis direction of the photosensitive drum  103  and the direction of movement of the optical print head  105  that is moved by the movement mechanism  640 . In other words, the first wall portion  760  is provided to the right-side rim of the opening  161 , and the second wall portion  761  is provided to the left-side rim of the opening  161 . The first wall portion  760  and the second wall portion  761  both protrude downwards in the vertical direction from the first support portion  526 . 
     The contact face portion  763  is provided between the first wall portion  760  and the second wall portion  761 , so as to link the bottom faces of the first wall portion  760  and second wall portion  761 , as illustrated in  FIG. 19 . Multiple contact face portions  763  are provided with intervals therebetween in the present embodiment, as illustrated in  FIG. 19 . Part of the cable  555  comes into contact with the contact face portion  763  when the optical print head  105  is moved from the exposing position toward the retracted position. This contact with part of the cable  555  causes the portion of the cable  555  between the connector  504  and the contact face portion  763  to bend and flex. Note that the cable  555  may be bent instead of being flexed. Accordingly, the cable  555  will not protrude downwards in the vertical direction from the cable guide member  756  even when the optical print head  105  is situated at the retracted position. 
     An arrangement may be made where the contact face portion  763  is omitted from the cable guide member  756 . Note however, that in this case, the first wall portion  760  and second wall portion  761  should be protruding downwards in the vertical direction farther than the region of the cable  555  exposed downwards in the vertical direction from the opening  161  and folded back toward the rear side of the apparatus main body when the optical print head  105  is situated at the retracted position. 
       FIGS. 20A and 20B  are diagrams for describing operations of the cable  555  in a case where the cable guide member  756  does not have the contact face portion  763  as described above.  FIG. 20A  illustrates a state where the optical print head  105  is at the exposing position, and  FIG. 20B  illustrates a state where the optical print head  105  is at the retracted position. 
     The cable  555  connected to the connector  504  extends downwards in the vertical direction from the connector  504 , as illustrated in  FIG. 20A . The cable  555  passes through the opening  161  formed in the first support portion  526 , and is folded back and extends toward the rear side of the image forming apparatus  1  (direction of arrow B in  FIG. 20A ). The cable  555  has the shape thereof fixed by adhesive agent or the like, for example, in order to maintain the folded-back state. Accordingly, even in a case where the optical print head  105  is at the retracted position as illustrated in  FIG. 20B , the cable  555  is not exposed downwards in the vertical direction from the first wall portion  760  and second wall portion  761  directly below the connector  504 . Thus, the portion of the cable  555  situated directly below the connector  504  does not come into contact with the edge of the opening  2010  formed in the front-side plate  642 , even in a case where the first support portion  526  is moved between the mounted position and the drawn-out position in a state where the optical print head  105  is at the retracted position. However, the cable  555  does not flex directly below the connector  504  when the optical print head  105  moves to the retracted position as in the first embodiment, so the size of this exposing unit is larger in the vertical direction as compared to the exposing unit in the first embodiment. 
     Although the above-described embodiments use four image forming units and optical print heads, the numbers used are not restrictive, and may be appropriately set as necessary. 
     Although a printer has been exemplified as the image forming apparatus in the above-described embodiments, the present disclosure is not restricted to this. The present disclosure may be applied to other image forming apparatuses such as photocopiers, facsimile devices, and so forth, or multi-function peripherals (MFP) where these functions are combined, thereby obtaining the same benefits. 
     Embodiment(s) of the present disclosure can also be realized by a computer of a system or apparatus that reads out and executes computer executable instructions (e.g., one or more programs) recorded on a storage medium (which may also be referred to more fully as a ‘non-transitory computer-readable storage medium’) to perform the functions of one or more of the above-described embodiment(s) and/or that includes one or more circuits (e.g., application specific integrated circuit (ASIC)) for performing the functions of one or more of the above-described embodiment(s), and by a method performed by the computer of the system or apparatus by, for example, reading out and executing the computer executable instructions from the storage medium to perform the functions of one or more of the above-described embodiment(s) and/or controlling the one or more circuits to perform the functions of one or more of the above-described embodiment(s). The computer may include one or more processors (e.g., central processing unit (CPU), micro processing unit (MPU)) and may include a network of separate computers or separate processors to read out and execute the computer executable instructions. The computer executable instructions may be provided to the computer, for example, from a network or the storage medium. The storage medium may include, for example, one or more of a hard disk, a random access memory (RAM), a read-only memory (ROM), a storage of distributed computing systems, an optical disk (such as a compact disc (CD), digital versatile disc (DVD), or Blu-ray Disc (BD)™), a flash memory device, a memory card, and the like. 
     While the present disclosure has been described with reference to exemplary embodiments, it is to be understood that the disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2018-132659, filed Jul. 12, 2018, which is hereby incorporated by reference herein in its entirety.