Abstract:
An image forming apparatus includes an image forming portion, a casing, an image reading portion, a first controller substrate provided on one of side surfaces of the casing, a second controller substrate provided on the side surface, wherein a component mounting surface of the second controller substrate is in a non-overlapping position with a component mounting surface of the first controller substrate, an electric wire configured to connect the first controller portion and the image reading portion, and a shielding member fixed to the casing so as to be provided between the electric wire and the second controller substrate and configured to shield electromagnetic radiation from the second controller substrate toward the electric wire.

Description:
FIELD OF THE INVENTION AND RELATED ART 
       [0001]    The present invention relates to an image forming apparatus such as a printer, a copying machine, a facsimile machine or a multi-function machine. 
         [0002]    Conventionally, in the image forming apparatus, a constitution in which in addition to a main controller substrate for controlling an image forming operation, an auxiliary controller substrate (additional substrate) for imparting a facsimile (FAX) function is capable of being additionally mounted has been known. For example, Japanese Laid-Open Patent Application (JP-A) 2004-85944 discloses a constitution in which a FAX function expansion board is directed connected with an on-board connector of a controlling board for controlling a mechanical operation of the image forming apparatus. 
         [0003]    Further, conventionally, an image forming apparatus in which an image reading portion is provided at an upper portion of a casing and in which a scanner function and a printer function are realized in combination has been known. In such a constitution, image information acquired at the image forming portion is transmitted to a main controller substrate provided on a side surface of the casing in many cases. 
         [0004]    As regards the image forming apparatus including the image reading portion, as in the image forming apparatus disclosed in JP-A 2004-85944, it would be considered that an additional substrate is made additionally mountable. In this case, it would be considered that the image forming apparatus is downsized by spacing the additional controller substrate from the main controller substrate thereby to cause a cover member for covering these controller substrates to approach the casing side surface. However, in such a constitution, an electric wire connecting the image reading portion and the main controller substrate passes through the neighborhood of the additional substrate in some cases, so that there was a liability that a signal transmitted via the electric wire is deteriorated by electromagnetic noise generating from the additional substrate. 
       SUMMARY OF THE INVENTION 
       [0005]    A principal object of the present invention is to provide an image forming apparatus capable of reducing an influence of electromagnetic noise on an electric wire connecting an image reading portion and a controller substrate in a constitution in which a plurality of controller substrates are provided on a side surface of a casing. 
         [0006]    According to an aspect of the present invention, there is provided an image forming apparatus comprising: an image forming portion configured to form an image; a casing configured to accommodate the image forming portion; an image reading portion provided above the casing and configured to read image information from an original; a first controller substrate provided on one of side surfaces of the casing and configured to control the image forming portion on the basis of the image information from the image reading portion; a second controller substrate provided on the side surface, wherein a component mounting surface of the second controller substrate is in a non-overlapping position with a component mounting surface of the first controller substrate; an electric wire configured to connect the first controller portion and the image reading portion and provided along the component mounting surface of the second controller substrate; and a shielding member fixed to the casing so as to be provided between the electric wire and the second controller substrate and configured to shield electromagnetic radiation from the second controller substrate toward the electric wire. 
         [0007]    Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a perspective view of an image forming apparatus according to the present invention. 
           [0009]      FIG. 2  is a schematic view showing a structure of the image forming apparatus. 
           [0010]      FIG. 3  is a rear view, of an upper portion of an apparatus main assembly, showing controller substrates and a wiring path. 
           [0011]      FIG. 4  is a rear view of the upper portion of the apparatus main assembly on which a holding member is mounted. 
           [0012]      FIG. 5  is a block diagram showing a control constitution of the image forming apparatus. 
           [0013]      FIG. 6  is a rear view of the upper portion of the apparatus main assembly on which a FAX substrate is mounted. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0014]    An image forming apparatus according to the present invention will be described with reference to the drawings. An image forming apparatus  1  shown in  FIG. 1  is a full-color laser printer. In the following description, as regards a side (right from side of  FIG. 1 ) where an operating portion  30  is provided on an apparatus main assembly  10 , a side surface in the side is a “front surface” and a side surface in a side opposite from the (front surface) side is a “rear surface”. Further, a right-hand side surface of the apparatus main assembly  10  as seen from the front surface side is a “right side surface” and a side surface in a side opposite from the (right side surface) side is a “left side surface”. 
         [0015]    The image forming apparatus  1  roughly includes the apparatus main assembly  10  and an image reading portion  20  provided on the apparatus main assembly  10 . The apparatus main assembly  10  incorporates an image forming portion  101  described later, and form an image on a recording material fed from a feeding cassette  42  and discharges the recording material onto a discharge tray  19 . Further, at an upper portion of the apparatus main assembly  10 , the operation portion  30 , including a liquid crystal panel and buttons and the like, for operating the image forming apparatus  1  by a user is disposed. 
         [0016]    As shown in  FIG. 2 , the image reading portion  20  for reading image information from an original includes a reading device body  21  provided with a platen glass and a platen cover  22  openable relative to the reading device body  21 . The original placed on the platen glass is subjected to extraction of the image information by being scanned by a scanning optical system, of a CCD type, a CIS type or the like, incorporated in the reading device body  21 . 
         [0017]    The image forming portion  101  for forming the image on the basis of the image information received from the image reading portion  20  or an external device is accommodated inside a casing  11  constituting the apparatus main assembly  10 . The image forming portion  101  has a constitution of a so-called tandem intermediary transfer type in which four image forming unit is PY, PM, PC and PK each including a photosensitive drum  2  are provided. The image forming units PY, PM, PC and PK form toner images of yellow (Y), magenta (M), cyan (C) and black (K), so that an image is formed on a recording material S via an intermediary transfer belt  7 . 
         [0018]    In each of the image forming units PY, PM, PC and PK, at a periphery of the photosensitive drum  2  which is a photosensitive member such as an organic photoconductor (OPC) member, a charger, a developing device and a cleaner (which are not shown) are provided. The photosensitive drum  2  is electrically charged at a surface thereof uniformly by the charger, and thereafter is exposed to laser light emitted from an exposure unit  3 , so that an electrostatic latent image is formed on the surface of the photosensitive drum  2 . The developing device supplies a charged toner to the photosensitive drum  2  and develops the electrostatic latent image into a toner image. The toner image formed on the photosensitive drum  2  is primary-transferred onto the intermediary transfer belt  7  by a primary transfer roller  5  opposing the photosensitive drum  2  via the intermediary transfer belt  7 . 
         [0019]    The intermediary transfer belt  7  which is an intermediary transfer member is rotationally driven in a predetermined direction along a feeding direction (upward direction in  FIG. 1 ) of the recording material S at a secondary transfer portion T 2 . On the surface of the intermediary transfer belt  7 , monochromatic toner images formed by the respective image forming units are multiple-transferred and thus a full-color toner image is formed. The toner image carried on the intermediary transfer belt  7  is secondary-transferred onto the recording material S at the secondary transfer portion T 2  formed between a secondary transfer roller  13  and an opposite roller  9 . 
         [0020]    In parallel to such an image forming process, the recording material S is supplied to the image forming portion  101  by respective elements of a feeding system  102  provided in the apparatus main assembly  10 . A feeding portion  40  provided at a lower portion of the apparatus main assembly  10  includes a feeding cassette  42  for accommodating the recording material S and a feeding unit  41  for separating and feeding the recording material S, accommodated in the feeding cassette  42 , one by one. The recording material S is a thin layer recording medium including paper such as a sheet or an envelope, or a plastic film such as a film for an overhead projector. 
         [0021]    The recording material S fed by the feeding unit  41  is subjected to correction of oblique movement by a registration roller pair  12 , and is fed toward the secondary transfer portion T 2  by the registration roller pair  12  in synchronism with transfer timing of the toner image. At the secondary transfer portion T 2 , the recording material S on which the (unfixed) toner image is formed is fed to a fixing device  14  including a roller pair and a heating source and the like, in which the recording material S is heated and pressed. As a result, the toner is melt-fixed on the recording material S, and the recording material S on which a fixed image is formed is discharged by a discharging roller pair  18  onto a discharge tray  19  provided at an upper portion of the image forming portion  101 . In the case of double-side printing, the recording material S is fed by the discharging roller pair  18  in a switch-back manner, and thereafter, the recording material S is fed to the image forming portion  101  again by a feeding roller pair  17  for the double-side printing. Then, when the image is formed on a back surface of the recording material S at the secondary transfer portion T 2  and the fixing device  14 , the recording material S is discharged onto the discharge tray  19  by the discharging roller pair  18 . 
       [Arrangement of Controller Substrates and the Like] 
       [0022]    A constitution of the image forming apparatus  1  at a rear surface which is a side surface in one of sides of the image forming apparatus  1  will be described. As shown in  FIG. 3 , at an upper portion of a rear surface of the casing  11 , a main board  47  as a first controller substrate for controlling the image forming apparatus  1  is provided. The main board  47  is connected with the image reading portion  20  via an electric wire (cable)  51 , and controls an operation of the image forming portion  101  and the feeding system  102  on the basis of image information received from the image reading portion  20  and an operating signal inputted through the operating portion  30 . 
         [0023]    At a position deviated from the main board  47  as seen from the rear surface side, a power source substrate  103  for supplying electric power to the image forming portion  101  is provided. The “position deviated from (the main board  47 )” means that the power source substrate  103  and the main board  47  are in a positional relationship in which these members do not substantially overlap with each other except for a connector portion and a screw fastening constitution to the casing  11  and the like. The power source substrate  103  generates DC and AC high voltages and applies bias voltages to the chargers and the primary transfer rollers  5  of the image forming units PY, PM, PC and PK, and the secondary transfer roller  13  and the like. 
         [0024]    In the image forming apparatus  1 , an expansion board  201  which is an additional substrate is additionally mounted, so that it is possible to impart a function other than an image forming function (printing function). The expansion board  201  is an example of a second controller substrate. As such an extended function, it is possible to cite a communicating function (for example, a facsimile function and a network function) capable of sending image information to and receiving the image information from an external device via a telecommunication line. Further, it would be also considered that not only a finisher, an option feeder or the like is connected but also a substrate on which a controll function for controlling these additional devices is packaged is additionally mounted as the secondary controller substrate. Accordingly, the image forming apparatus  1  is capable of not only being used as a printer having a scanner function and a printing function in a state in which the expansion board  201  is demounted but also extending the function so as to meet a user&#39;s demand by mounting the expansion board  201 . 
         [0025]    In addition, at the back surface of the casing  11 , for example, a hard disk device (HDD)  48  connected with the main board  47  is provided. These members such as the main board  47 , the expansion board  201 , the HDD  48  and the power source substrate  103  are covered with a rear surface cover (not shown) detachably mountable to the casing  11 . 
         [0026]    A positional relationship among the main board  47 , the expansion board  201  and the power source substrate  103  will be described. These substrates may preferably be disposed so as to be spaced from each other since each of these substrates generates heat and electromagnetic noise during an operation thereof. On the other hand, from the viewpoint of downsizing of the apparatus main assembly  10 , it is desired that these substrates including wiring for connecting these substrates are accommodated inside a contour of the casing  11  as seen from the rear surface side. Further, in general, the power source substrate  103  has a larger weight than the main board  47  and the expansion board  201 , and therefore, these is a need to take a weight balance of the apparatus main assembly  10  into consideration. 
         [0027]    Therefore, in this embodiment, these substrates are not only disposed at positions spaced from each other as seen in a flat surface, i.e., as seen from the rear surface side, but also have a constitution in which an influence of the electromagnetic noise is reduced by a holding member  50  described later. 
         [0028]    Specifically, it is suitable that the main board  47  is disposed in one side with respect to a widthwise direction (left-right direction), and the expansion board  201  and the power source substrate  103  are disposed in the other side with respect to the widthwise direction. At this time, not only the power source substrate  103  is disposed below the expansion board  201 , but also the connecting portion  51   a  for connecting the electric wire  51  with the main board  47  is disposed at a side end portion and above the power source substrate  103 . 
         [0029]    By such an arrangement, it becomes easy to design a wiring path of the electric wire  51  so as to avoid the power source substrate  103  which has large internal energy and which is liable to constitute a generating source of the electromagnetic noise. Further, the connecting portion  51   a  is positioned at the side end portion of the main board  47 , and therefore, the electric wire  51  is connectable to the main board  47  from a one end side with respect to the widthwise direction. For this reason, even in the case where an interval between the main board  47  and the image reading portion  20  with respect to a vertical (up-down) direction is narrow, compared with a constitution in which the connecting portion  51   a  is disposed at an upper end portion, a connecting operation of the electric wire  51  becomes easy. Further, the power source substrate  103  having a relatively large weight is positioned below the expansion board  201 , so that stability of the apparatus main assembly  10  is improved. 
         [0030]    In such an arrangement, the electric wire  51  extends via an overlapping position with the expansion board  201  as seen from the rear surface side. Therefore, as shown in  FIG. 4 , the holding member  50  is provided between the electric wire  51  and the expansion board  201  and is caused to hold the electric wire  51 . The holding member  50  has a size capable of covering at least a region where the electric wire  51  and the expansion board  201  overlap with each other and is formed of a material, such as an electroconductor which is metal or the like or a resin material having an electroconductor film, capable of shielding electromagnetic wave generating from the expansion board  201 . 
         [0031]    As a result, the expansion board  201  is disposed at the position deviated from the main board  47 , and in a constitution in which the electric wire  51  passes through the rear surface side of the expansion board  201 , the influence of the electromagnetic noise on the electric wire  51  can be reduced. Further, the image information read by the image reading portion  20  is transmitted to the main board  47  without being influenced by the electromagnetic noise, whereby faithfulness of an output image, outputted by the image forming apparatus  1 , on an original image is improved. However, the output image includes not only the toner image formed on the recording material S but also image information sent to the external device. 
         [0032]    In the above, the constitution in which the first controller substrate and the second controller substrate are disposed on the rear surface as one of the side surface in one side of the apparatus main assembly was described, but these controller substrates may also be disposed on another side surface (right side surface, for example) of the apparatus main assembly. 
         [0033]    As an example to which the above-described embodiment is applied, an image forming apparatus  1  in which a FAX board  200 , as the second controller substrate, having the facsimile function is mounted will be described. As shown in  FIGS. 5 and 6 , a main controller  45  of the image forming apparatus  1  includes a central processing unit (CPU), a storing device (RAM, ROM) and a HDD  48  which are mounted on the main board  47 . The main controller  45  controls an operation of an entirety of the image forming apparatus  1  by sending signals to and receiving the signals from the respective portions, of the image forming apparatus  1 , such as the operating portion  30 , the image forming portion  101  and the image reading portion  20 . 
         [0034]    The FAX board  200  in this embodiment is interposed between the main board  47  and a telephone line and sends image information, received from the main board  47 , to a remote external device via the telephone line, or processes signals received from the external device and then transmits the signals, as image information, to the main board  47 . The FAX board  200  includes a controller substrate  202 , as the second controller substrate, having a modem function for modulating a signal, corresponding to image information, depending on a characteristic of the telephone line. 
         [0035]    Further, a USB cable  53  is held by a holding member  52  provided so as to cover a plurality of integrated circuits mounted on the controller substrate  202 . As a result, in the image forming apparatus  1  having the FAX function, the influence of the electromagnetic noise generating from the FAX board  200  is reduced, so that faithfulness of the output image can be improved. 
         [0036]    According to the present invention, in a constitution in which a plurality of controller substrates are provided on a side surface of a casing, the influence of electromagnetic noise on an electric wire connecting an image reading portion and the controller substrates can be reduced. 
         [0037]    While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention 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. 
         [0038]    This application claims the benefit of Japanese Patent Application No. 2016-122954 filed on Jun. 21, 2016, which is hereby incorporated by reference herein in its entirety.