Patent Publication Number: US-11661295-B2

Title: Supporting frame of sheet feeding device and sheet feeding device including the supporting frame

Description:
FIELD OF THE INVENTION AND RELATED ART 
     The present invention relates to a supporting frame of a sheet feeding device for supporting an inner unit of a sheet feeding device. 
     Inside an image forming apparatus such as a copying machine or a printer and inside a sheet processing device, respecting unit including an image forming portion for forming an image on a sheet (recording material), such as a photosensitive drum or a developing device, and a feeding roller for feeding the sheet and the like are incorporated. 
     Further, each of the units incorporated in these apparatuses (devices) is supported by a supporting frame constituted by a metal plate or the like in general. Specifically, by a pair of side plates provided opposed to each other, one end and the other end of the incorporated unit are supported, respectively. 
     Accordingly, in the case where a relative position between the pair of side plates is deviated, a relative position between the one end and the other end of the incorporated inner unit is deviated, so that positional accuracy of the unit deterioration. For example, in the case where the incorporated unit is a feeding unit including a feeding roller pair, parallelism between rotation shafts of the respective rollers of the feeding roller pair is deviated, so that there was a liability that the sheet fed by the feeding roller pair is moved obliquely. 
     In order to solve this problem, Japanese Laid-Open Patent Application (JP-A) 2006-208597 discloses a constitution in which a pair of side plates is fixed to a base member in a state in which the base member is sandwiched between the pair of side plates. 
     However, in the constitution disclosed in JP-A 2006-208597, a relative position between the pair of side plates depends on parallelism of the base member. That is, in the case inclination such as warpage or distortion occurs on the base member, each of the pair of side plates is inclined or falls or the like, so that there was a liability that the relative position deviates. By this, there was a liability that positional accuracy of a unit supported by the pair of side plates becomes poor. 
     SUMMARY OF THE INVENTION 
     A principal object of the present invention is to provide a sheet feeding device supporting frame capable of improving accuracy of a relative position between a pair of side plates. 
     According to an aspect of the present invention, there is provided a supporting frame of a sheet feeding device for supporting a feeding unit including a feeding roller pair capable of nipping and feeding a sheet, comprising: a bottom plate; a first side plate fixed to the bottom plate and supporting one end side of the feeding unit with respect to a rotational axis direction of the feeding roller pair; and a second side plate fixed to the bottom plate with a predetermined interval from the first side plate and supporting the other end side of the feeding unit with respect to the rotational axis direction of the feeding roller pair, wherein the first side plate includes a supporting portion supporting the one end side of the feeding unit, a first bent and erected portion bent and erected substantially perpendicular to the supporting portion, and a second bent and erected portion provided on a side opposite from the first bent and erected portion with respect to a sheet feeding direction of the feeding unit and bent and erected substantially perpendicular to the supporting portion, wherein the supporting portion includes a swing center portion having a swing center of the first side plate when the first side plate is positionally adjusted relative to the second side plate, and wherein in a direction in which a bending edge line formed between the supporting portion and the first bent and erected portion extends, the swing center portion projects downward than a lower end portion of the first bent and erected portion and a lower end portion of the second bent and erected portion are and contacts the bottom plate. 
     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 
         FIG.  1    is a sectional view of an image forming system. 
         FIG.  2    is a perspective view of an inner unit of an inspecting device. 
       Parts (a) and (b) of  FIG.  3    are perspective views of a supporting frame for the inspecting device. 
       Parts (a), (b) and (c) of  FIG.  4    are schematic views for illustrating inclination of front and rear side plates. 
         FIG.  5    is an illustration of a bottom plate contact portion of a front-side plate. 
       Parts (a) and (b) of  FIG.  6    are enlarged views of the front-side plate. 
         FIG.  7    is a perspective view for illustrating assembling of the supporting frame when a right-angled jig is mounted. 
         FIG.  8    is a perspective view for illustrating the assembling of the supporting frame when the rear side plate is mounted. 
         FIG.  9    is a perspective view for illustrating the assembling of the supporting frame when the front-side plate is mounted. 
         FIG.  10    is a perspective view of a front-side plate positioning jig. 
         FIG.  11    is a perspective view for illustrating the assembling of the side plate when the front-side plate positioning jig is mounted. 
         FIG.  12    is a perspective view of the supporting frame after the assembling. 
       Parts (a) and (b) of  FIG.  13    are schematic views for illustrating a supporting frame of a second embodiment. 
     
    
    
     DESCRIPTION OF THE EMBODIMENTS 
     Embodiments of the present invention will be specifically described with reference to the drawings. As regards dimensions, materials, shapes and relative arrangement of constituent elements described in the following embodiments, the scope of the present invention is not intended to the limited to the following embodiments. 
     Embodiment 1 
       FIG.  1    is a schematic structural view of an image forming system  100  including an image forming apparatus  101 , an inspecting device (apparatus)  102  connected thereto and downstream thereof with respect to a recording material feeding direction, and a sorting device (apparatus)  103  connected to the inspecting device  102  and downstream of the inspecting device  102  with respect to the recording material feeding direction. Each of the image forming apparatus  101 , the inspecting device  102  and the sorting device  103  is provided with casters disposed on an installing surface and is independently movable. 
     The image forming apparatus  101  is a four-color-based printer using an electrophotographic process. The image forming apparatus  101  is capable of forming a toner image on a sheet S on the basis of an image signal inputted from an information terminal such as a personal computer or from an unshown external device such as an image reader to an unshown controller. The sheet S is a recording material (or medium) on which the toner image is capable of being formed and includes plain paper, thick paper, an OHP sheet, coated paper, label paper and the like. 
     Inside the image forming apparatus  101 , four image forming portions  10 Y,  10 M,  10 C and  10 K for forming toner images of yellow (Y), magenta (M), cyan (C) and black (K), respectively, are provided. These four image forming portions  10  are different in color of toners used, but have similar detailed constitutions, and therefore, the detailed constitution of the image forming portions  10  will be described using the image forming portion  10 Y for yellow as an example. The image forming portion  10  includes an electrophotographic photosensitive drum  1  as an image bearing member, a charging device  2 , an exposure unit  3 , a developing unit  4 , a primary transfer roller  5  and a drum cleaner  6 . In order to avoid complicatedness of  FIG.  1   , reference numerals of these constituent elements in the image forming portions  10 M,  10 C and  10 K other than the image forming portion  10 Y are omitted from  FIG.  1   . Further, an electrophotographic process and an image forming operation in each of the image forming portions are well known, and therefore, will be omitted from description. 
     Under the image forming portions  10 , an intermediary transfer belt  50  is provided. The intermediary transfer belt  50  is stretched by a driving roller  51 , a tension roller  52 , and an inner secondary transfer roller  53 , and is driven (rotated) in an arrow J direction in  FIG.  1   . 
     The toner image formed on the photosensitive drum  1  in each of the image forming portions  10  is transferred onto the intermediary transfer belt  50  by passing through a primary transfer nip formed by the photosensitive drum  1  and the primary transfer roller  5  of each image forming portion  10  through the intermediary transfer belt  50 . Then, the color toner images are transferred superposedly from the photosensitive drums  1  of the respective image forming portions  10  onto the rotating intermediary transfer belt  50  while the intermediary transfer belt  50  rotates. By this, an unfixed color image including the superposed four color toner images of yellow, magenta, cyan and black is formed on the intermediary transfer belt  50 . 
     On the other hand, sheets S are fed one by one from a cassette  24 , and the fed sheet S is conveyed along a feeding passage  13  to a secondary transfer nip, at predetermined control timing, formed between the intermediary transfer belt  50  and a secondary transfer roller  14 . By this, onto the sheet S, the toner images on the intermediary transfer belt  50  are secondary-transferred. Here, transfer residual toner remaining on the intermediary transfer belt  50  after the secondary transfer of the toner images onto the sheet S is removed from the belt surface by a belt cleaner  19 . 
     Thereafter, the sheet S on which the toner images are transferred is heated and pressed by a fixing device  16 , so that the toner images are fixed on the sheet S. The sheet S passed through the fixing device  16  is discharged from the image forming apparatus  101  by a discharging roller pair  17 . 
     The sheet S discharged from the image forming apparatus  101  is delivered to a first feeding roller pair  201  in the inspecting device  102  connected to the image forming apparatus  101  on a side downstream of the image forming apparatus  101  with respect to a sheet feeding direction. At this time, a feeding speed of the sheet S in the first feeding roller pair  201  is the same as a feeding speed in the discharging roller pair  17  of the image forming apparatus  101 . 
     Next, the sheet S is fed to a first contact image sensor (hereinafter referred to as “CIS”) unit  202 . The first CIS unit  202  is provided as a sensor for reading image information on a back surface of the sheet S. At a position opposing a sheet S passing surface of the first CIS unit  202  with respect to the feeding passage, a first pressing roller  203  is provided. Further, the first pressing roller  203  presses the passing sheet S toward the first CIS unit  202  side by an unshown spring. Further, the first pressing roller  203  rotates at the same feeding speed as the feeding speed of the first feeding roller pair  201  so as to feed the sheet S. Therefore, the first pressing roller  203  presses the sheet S toward the first CIS unit  202  so that the sheet S passing through the first CIS unit  202  passes through a focal position of the first CIS unit  2022  while maintaining a certain distance from the first CIS unit  202 , and thus reliably carries out an image reading process on the sheet S by the first CIS unit  202 . 
     On a side downstream of the first CIS unit  202  with respect to the sheet S feeding direction, a second CIS unit  204  and a second pressing roller  205  are provided. The second CIS unit  204  is used for reading image information on a front surface of the sheet S. Here, the second CIS unit  204  has the same constitution and function as those of the first CIS unit  202  disposed upstream of the second CIS unit  204 . By employing such a constitution, the inspecting device  102  is capable of reading the image information on the front surface of the sheet S and the image information on the back surface of the sheet S only by causing the sheet S to pass through the inspecting device  102  once. 
     In this embodiment, a constitution in which the image information on the back surface of the sheet S is read in the first CIS unit  202  disposed on an upstream side of the sheet feeding direction and the image information on the front surface of the sheet S is read in the second CIS unit  204  was employed. Here, the front surface of the sheet S is a first surface on which an image is first formed at the second transfer nip in the image forming apparatus  101 . Further, the back surface of the sheet S is a second surface, opposite from the first surface, on which an image is formed by causing the sheet S on which the image is formed on the front surface in the image forming apparatus  101  to pass through the secondary transfer nip after the sheet S is turned upside down in a reverse feeding passage. That is, the front surface of the sheet S is the surface on a side where the sheet S opposes the intermediary transfer belt  50  when the sheet S first passes the secondary transfer nip of the image forming apparatus  101 , and the back surface of the sheet S is the surface on a side where the sheet S opposes the intermediary transfer belt  50  when the sheet secondly passes through the secondary transfer nip of the image forming apparatus  101 . 
     In this embodiment, the upstream-side first CIS unit  202  with respect to the sheet feeding direction was used for reading the back surface, and the downstream-side second CIS unit  204  was used for reading the front surface, but a reverse constitution may also be employed. When a constitution in which the first surface of the sheet S discharged from the image forming apparatus  101  is read by one CIS unit and the second surface of the sheet S opposite in side from the first surface of the sheet S is read by the other CIS unit is employed, an arrangement order of the first and second CIS units  202  and  204  with respect to the sheet feeding direction and a direction of the sheet discharged from the image forming apparatus  101  may also be appropriately changed. 
     Further, the sheet S passed through the second CIS unit  204  is discharged from the inspecting device  102  by being nipped and fed by a second feeding roller pair  206 . Here, the first feeding roller pair  201  and the second feeding roller pair  206  are examples of a feeding roller pair capable of nipping and feeding the sheets and examples of a feeding unit. 
     As shown in  FIG.  1   , a sheet feeding passage of the inspecting device  102  is substantially horizontal, and therefore, the sheet S is fed substantially horizontally. That is, a nip of the first feeding roller pair  201 , a nip between the first CIS unit  202  and the first pressing roller  203 , a nip between the second CIS unit  204  and the second pressing roller  205 , and a nip of the second feeding roller pair  206  have the substantially same height (level) from an installation surface of the inspecting device  102 . Accordingly, the inspecting device  102  is capable of reading the image information without imposing stress on the sheet such that the sheet S fed is bent. 
     Then, the sheet S discharged from the inspecting device  102  is fed to the sorting device  103  and then is discharged onto either one of trays  104  and  105  by the sorting device  103 . By this, a series of operations from the feeding of the sheet S to the discharge of the sheet S in the image forming system  100 . 
     Next, an inspecting process of the sheet S in the image forming system  100  will be described. In the image forming system  100  in this embodiment, the image formed on the sheet S by the image forming apparatus  101  is read by the inspecting device  102 , so that presence or absence of an abnormal image for the image formed on the sheet S can be discriminated. Further, the sheet S is discharged by switching the trays  104  and  105  by the sorting device  103 , so that a sorting process based on a discrimination result of the presence or absence of the abnormal image can be performed. That is, in the image forming system  100 , the image formed by the image forming apparatus  101  is inspected, and then the sorting process depending on an inspection result can be carried out. Here, the inspecting device  102  is an image reading apparatus (device) for reading the image information on the sheet S in order to acquire the image information on the sheet S and is a sheet feeding device for feeding the sheet S in order to read the image information. 
     In the case where occurrence or non-occurrence of abnormality of the image information on the sheet S outputted from the image forming apparatus  101  in the image forming system  100  in this embodiment, a sheet S on which a reference image is formed is caused to pass through the inspecting device  102 , and then image data read by the inspecting device  102  through the first CIS unit  202  and the second CIS unit  204  is registered as reference image data in an external computer connected to the image forming system  100 . 
     Thereafter, the images on the sheet S outputted and fed from the image forming apparatus  101  are read by the first CIS unit  202  and the second CIS unit  204 , so that image data are acquired. The external computer compares each of the image data with the registered image data as the reference image data, and the sheet S for which a difference between the read image data and the reference image data is detected is discriminated as being abnormal and then is subjected to the sorting process by the sorting device  103 . That is, in the sorting device  103 , the sheet S discriminated as being that there is no abnormal image is discharged onto the tray  104 , and the sheet S discriminated as being that the abnormal image is present is discharged onto the tray  105 , and thus the sorting process is performed. 
     Incidentally, in this embodiment, discrimination of the presence or absence of the abnormal image for the image data is made by using the external computer in this embodiment, but when the discrimination of the abnormal image can be carried out by the image forming system  100  as a whole, the discrimination of the abnormal image can be carried out by any of the controller. For example, a constitution in which the discrimination of the presence or absence of the abnormal image is made by an unshown controller provided in the image forming apparatus  101  may also be employed. Further, a constitution in which the discrimination of the presence or absence of the abnormal image is made by an unshown controller provided in the inspecting device  102  may also be employed. 
     Next, a structure of inner units of the inspecting device  102  will be described using  FIG.  2   .  FIG.  2    is a perspective view showing the first feeding roller pair  201 , the first CIS unit  202 , the first pressing roller  203 , the second CIS unit  204 , the second pressing roller  205  and the second feeding roller pair  206  which are the inner units of the inspecting device  102 . 
     In this embodiment, an arrow F direction shows a front side, an arrow B direction shows a back (rear) side, an arrow R direction shows a right side, an arrow L direction shows a left side, an arrow U direction shows an upward (upper) side, and an arrow d direction shows a downward (lower) side. That is, a left-right direction in  FIG.  2    is a left-right direction in  FIG.  1   , and an up-down direction in  FIG.  2    is an up-down direction in  FIG.  1   . Here, with respect to the up-down direction in  FIGS.  1  and  2   , a direction from U toward D is a vertical direction. 
     In  FIG.  2   , the sheet S enters the first feeding roller pair  201  from an arrow P direction and is discharged toward an arrow Q direction by the second feeding roller pair  206 . That is, the sheet feeding direction in the inspecting device  102  is a direction from the right toward the left on the drawing sheet of  FIG.  2   , and the first feeding roller pair  201  is provided on a side upstream of the first CIS unit  202  and the second feeding roller pair  206  is provided on a side downstream of the second CIS unit  204 , with respect to the sheet feeding direction. 
     The first feeding roller pair  201  includes a feeding roller  211  including a steel shaft  211   a  provided with two silicone rubbers  211   b  of 20 mm in outer diameter and includes a roller  212  made of a POM resin material and mounted on each of the silicone rubbers  211   b  at an associated position. 
     Here, the feeding roller  211  has a constitution in which rotational drive is given thereto from an unshown driving motor provided on a rear end portion of  FIG.  2    through a timing belt and thus the steel shaft  211   a  is rotated. The rollers  212  has a constitution in which an unshown rotation shaft thereof is rotatably shaft-supported and is urged by the feeding roller  211 , and thus is rotated by the feeding roller  211 . 
     The first CIS unit  202  includes a transparent glass  202   a  at a surface where the sheet S fed by the first pressing roller  203  is pressed against the transparent glass  202   a . Further, the first CIS unit  202  is capable of reading the image data by reading the image on the sheet S fed between the transparent glass  202   a  and the first pressing roller  203  through the transparent glass  202   a  by an unshown light source and an unshown light receiving sensor which are provided inside the transparent glass  202   a.    
     The first pressing roller  203  is constituted by press-fitting a shaft  203   b  into an aluminum pipe material  203   a  at opposite end portions of the pipe material  203   a  and then by coating an outer peripheral surface of the pipe material  203   a  with a black urethane resin material. The first pressing roller  203  is 20 mm in outer diameter. Further, to a rear end portion of the first pressing roller  203  in  FIG.  2   , rotational drive is given from an unshown driving motor through a timing belt. Further, to the first pressing roller  203 , pressure of 5.9 N is imparted by an unshown spring, so that the first pressing roller  203  is urged toward the first CIS unit  202 . 
     Incidentally, constitutions of the second CIS unit  204  and the second pressing roller  205  are similar to the constitutions of the first CIS unit  202  and the first pressing roller  203 , respectively, and therefore, their constituent elements are represented by similar reference numerals or symbols and will be omitted from description. Further, a constitution of the second feeding roller pair  206  is the same as the constitution of the first feeding roller pair  201 , and therefore, constituent elements thereof are represented by the same reference numerals or symbols and will be omitted from description. 
     Here, the first feeding roller pair  201 , the second feeding roller pair  206 , the first CIS unit  202 , the second CIS unit  204 , the first pressing roller  203  and the third pressing roller  205  which are the inner units of the inspecting device  102  have to be fixed in a state in which positional accuracy of each of the inner units is maintained. This is because if the positional accuracy is poor and each of the inner units is fixed in an inclined state, the feeding of the sheet S cannot be carried out linearly and thus the sheet S is fed in an obliquely moved state. Thus, when the sheet S is fed in the obliquely moved state, reading of the image data by the first CIS unit  202  and the second CIS unit  204  cannot be properly carried out in some cases, so that there is a liability that the discrimination of the abnormal image cannot be made. 
     Therefore, in this embodiment, in order to enhance the positional accuracy of the inner units of the inspecting device  102 , a constitution in which positional accuracy of a supporting frame for supporting the inner units is enhanced is employed. In the following, the supporting frame will be described. 
     Parts (a) and (b) of  FIG.  3    are perspective views showing a supporting frame  300  of the inspecting device  102 , in which a state such that an outer casing cover or the like forming an outer appearance of the inspecting device  102  is removed is shown. Part (a) of  FIG.  3    is the perspective view showing the supporting frame  300  in a state in which the inner units are removed, and part (b) of  FIG.  3    is the perspective view showing the supporting frame  300  in a state in which the supporting frame  300  supports the inner units. Here, the supporting frame  300  in parts (a) and (b) of  FIG.  3    is viewed from a side of a rear-side plate  303  provided on a rear surface side B of the inspecting device  102 . 
     The supporting frame  300  of the inspecting device  102  is constituted by a bottom plate  301 , a front-side plate  302 , the rear-side plate  303 , a right rail stay  304 , a left rail stay  305 , a link stay  306  and a stay  307 . 
     Each of the front-side plate  302  and the rear-side plate  303  is fixed to the bottom plate  301 . Details of a fixing structure of the supporting frame  300  will be described later. Each of the right rail stay  304 , the left rail stay  305 , the link stay  306  and the stay  307  is fixed to the front-side plate  302  on one end side and is fixed to the rear-side plate  303  on the other end surface with respect to a longitudinal direction (front-rear direction FR). 
     Four casters  308  are device on a lower surface of the bottom plate  301  with respect to a plate thickness direction, i.e., on an installation surface side of the bottom plate  301  so that the two casters  308  and other two casters  308  are positioned on the front side and the rear side, respectively. Thus, by the plurality of casters  308 , the inspecting device  102  is movable on the installation surface. 
     Further, as shown in  FIG.  1   , the image forming apparatus  101  is provided with a plurality of casters  60 , and the sorting device  103  is provided with a plurality of casters  70 . By this, each of the devices (apparatuses) in the image forming system is independently movable. That is, the inspecting device  102  is movable separately from the image forming apparatus  101  and the sorting device  103  in the image forming system  100 . 
     Further, the inspecting device  102  is provided with a fall-preventing caster  311  in addition to the casters  308 . The fall-preventing caster  311  is used for suppressing a fall of the inspecting device  102  in a left-right direction LR when the inspecting device  102  is moved by using the casters  308 . Further, the fall-preventing caster  311  is rotatable relative to the bottom plate  301 , and is accommodated below the bottom plate  301  in the case where the inspecting device  102  is connected to the image forming apparatus  101  in the image forming system  100  on a side downstream of the image forming apparatus  101  with respect to the sheet feeding direction. 
     As shown in part (b) of  FIG.  3   , as the inner units of the inspecting device  102 , each of the above-described first feeding roller pair  201  and second feeding roller pair  206  is rotatably fixed to the front-side plate  302  on one end side with respect to the longitudinal direction and is rotatably fixed to the rear-side plate  303  on the other end side with respect to the longitudinal direction. For example, the feeding roller  211  is rotatably fixed to the front-side plate  302  at one end side portion with respect to the rotational axis direction of the steel shaft  211   a  than the silicone rubbers  211   b  are, and is rotatably fixed to the rear-side plate  303  at the other end side portion opposite from the one end side portion with respect to the rotational axis direction than the silicone rubbers  211   b  are. For this reason, the front-side plate  302  and the rear-side plate  303  are provided with supporting horizontals through which end portions the steel shaft  211   a  of the feeding roller  211  on one end side and the other end side penetrate. 
     Further, each of the first CIS (sensor) unit  202 , the second CIS (sensor) unit  204 , the first pressing roller  203  and the second pressing roller  205  which are used as the inner units of the inspecting device  102  is supported by an inner unit frame  400 . The inner unit frame  400  is fixed to the front-side plate  302  on one end side with respect to the longitudinal direction (front-rear direction frame) and is fixed to the rear-side plate  303  on the other end side with respect to the longitudinal direction. Accordingly, each of the front-side plate  302  and the rear-side plate  303  is provided with an opening through which the inner unit frame  400  is supported and inserted. 
     The inner unit frame  400  is capable of being inserted into and extracted from the supporting frame  300  through the opening provided in the front-side plate  302  by being slid (moved) on the right rail stay  304  and the link stay  306  when the inner unit frame  400  is mounted in and dismounted from the supporting frame  300 . Thus, the inner unit frame  400  which is heavy can be easily mounted in and dismounted from the supporting frame  300 . 
     As shown in  FIG.  3   , the supporting frame  300  of the inspecting device  102  has a length with respect to the vertical direction (arrow UD direction) longer than a length with respect to the sheet S feeding direction (arrow RL direction, widthwise direction). That is, when a length of the front-side plate  302  (rear-side plate  303 ) with respect to the horizontal direction (widthwise direction) is X, X is 237 mm, and when a length from a fixing position between the rear-side plate  303  and the bottom plate  301  to a position where the feeding roller pairs  201  and  206  are supported is Y, Y is 664 mm. That is, a constitution in which the length Y from the contact position between the rear-side plate  303  and the bottom plate  301  to the nip of the first feeding roller pair  201  forming a feeding passage along which the sheet S is fed is two times or more longer than the length X with respect to the widthwise direction of the supporting frame  300  is employed. 
     Further, as regards the front-side plate  302  and the rear-side plate  303 , a maximum length with respect to the vertical direction is two times or more a maximum length with respect to the horizontal direction, and therefore, also as regards the supporting frame  300 , a maximum length with respect to the vertical direction is two times or more a maximum length with respect to the horizontal direction. 
     As described above, the nip position of the first feeding roller pair  201  and the nip position of the second feeding roller pair  206  are substantially equal in height (level) to each other for forming a substantially horizontal feeding passage so that the fed sheet is not bent. 
     Here, in the inspecting device  102 , the position of each of the first feeding roller pair  201  and the second feeding roller pair  206  with respect to the vertical direction relative to the front-side plate  302  and the rear-side plate  303  is determined by a position of a sheet discharge opening of the image forming apparatus  101  and a sheet receiving opening of the sorting device  103 . 
     Further, a length of the inspecting device  102  with respect to the widthwise direction is determined by a length of the feeding passage. Here, in order to shorten a discharging time from feeding of the sheet S in the image forming system  100  to discharge onto the tray  104  or  105 , it is desirable that a feeding path in the inspecting device  102  is short to the extent possible. In order to meet such a demand, the inspecting device  102  in this embodiment has the length with respect to the widthwise direction shorter than the length with respect to the vertical direction in order to realize a necessary minimum feeding passage length. That is, the length of the supporting frame  300  of the inspecting device  102  is shorter with respect to the widthwise direction than with respect to the vertical direction. 
     Here, in the case where flatness of the bottom plate  301  is low and the bottom plate  301  is inclined relative to the horizontal surface, the front-side plate  302  and the rear-side plate  303  which are fixed to the bottom plate  301  are in a state in which these plates are inclined relative to a vertical surface. Such a problem will be described using  FIG.  4   . Parts (a) to (c) of  FIG.  4    are schematic views for illustrating inclination of the front-side plate  302  and the rear-side plate  303 , in which part (a) shows a state of no inclination, part (b) shows a state in which the front-side plate  302  and the rear-side plate  303  are inclined in the same direction at the same angle, and part (c) shows a state in which the front-side plate  302  is inclined relative to the rear-side plate  303 . In this embodiment, it is assumed that each of the front-side plate  302  and the rear-side plate  303  is fixed so that an interval therebetween at an upper end portion and an interval therebetween at a lower end portion are equal to each other. 
     As shown in part (a) of  FIG.  4   , in the case where the flatness of the bottom plate  301  is high and the inclination such as warpage or distortion of the bottom plate  301  is not generated, the front-side plate  302  and the rear-side plate  303  are not inclined, and therefore, the inner units supported by the front-side plate  302  and the rear-side plate  303  are not inclined. Accordingly, a parallel state between the steel shaft  211   a  supporting the silicone rubbers  211   b  and the rotation shaft of the rollers  212  of the first feeding roller pair  201  is maintained. That is, a parallel state between the rotation shafts of the rotatable members is maintained so that parallelism between the rotation shafts of the rotatable members is high. 
     At this time, in the case where the bottom plate  301  is not inclined and thus the front-side plate  302  and the rear-side plate  303  are not inclined, the second feeding roller pair  206  is also similarly in a state in which parallelism between associated rotatable members is maintained. In this case, the sheet fed by the first feeding roller pair  201  and the second feeding roller pair  206  is not obliquely moved, so that the images on the sheet can be properly read by the first CIS unit  202  and the second CIS unit  204 . 
     Further, as shown in part (b) of  FIG.  4   , in the case where the inclination such as the warpage or the distortion of the bottom plate  301  is generated and in the case where in the bottom plate  301 , a front end portion to which the front-side plate  302  is fixed and a rear end portion to which the rear-side plate  303  is fixed are inclined at the same angle, the front-side plate  302  and the rear-side plate  303  are inclined in the same direction at the same angle. In this case, the inner units supported by the front-side plate  302  and the rear-side plate  303  are supported while following the inclination of the front-side plate  302  and the rear-side plate  303 . 
     However, the structure shown in part (b) of  FIG.  4    is in a state in which the front-side plate  302  and the rear-side plate  303  are inclined in the same direction at the same angle, and therefore, similarly as in the structure shown in part (a) of  FIG.  4   , a parallel state between the steel shaft  211   a  supporting the silicone rubbers  211   b  and the rotation shaft of the rollers  212  of the first feeding roller pair  201  is maintained. That is, a parallel state between the rotation shafts of the rotatable members is maintained so that parallelism between the rotation shafts of the rotatable members is high. 
     Thus, even in the case where the bottom plate  301  is not inclined and thus the front-side plate  302  and the rear-side plate  303  are not inclined, the second feeding roller pair  206  is also similarly in a state in which parallelism between the rotation shafts of associated rotatable members is maintained in a high state. Also, in this case, the sheet fed by the first feeding roller pair  201  and the second feeding roller pair  206  is not obliquely moved, so that the images on the sheet can be properly read by the first CIS unit  202  and the second CIS unit  204 . 
     Thus, in the case where the front-side plate  302  and the rear-side plate  303  are not inclined relative to each other as shown in part (a) of  FIG.  4    and in the case where the front-side plate  302  and the rear-side plate  303  are inclined in the same direction at the same angle, the fed sheet does not cause oblique movement. This is because parallelism between the rotation shafts supporting the rotatable member pairs comprising the first feeding roller pair  201  and the second feeding roller pair  206 . That is, the position where the first feeding roller pair  201  and the second feeding roller pair  206  are supported by the front-side plate  302  and the position where the first feeding roller pair  201  and the second feeding roller pair  206  are supported by the rear-side plate  303  do not provide differences with respect to the vertical direction and the left-right direction. 
     On the other hand, as shown in part (c) of  FIG.  4   , in the case where the inclination such as the warpage or the distortion of the bottom plate  301  in the case where inclination of the front end portion of the bottom plate  301  where the front-side plate  302  is fixed and inclination of the rear end portion of the bottom plate  301  where the rear-side plate  303  is fixed are different from each other, the front-side plate  302  and the rear-side plate  303  follow the bottom plate  301  and are inclined at different angles. 
     Here, in part (c) of  FIG.  4   , the side plate  301  indicated by a solid line and the casters  308  show the front end portion supporting the front-side plate  302 , and the bottom plate  301  indicated by a broken line and the casters  308  show the rear end portion of the rear-side plate  303 . In this case, the inner units supported by the front-side plate  302  and the rear-side plate  303  are also supported in a state in which the inner units follows the inclination of the front-side plate  302  and the rear-side plate  303  and thus are inclined. 
     Thus, in the case where the front-side plate  302  and the rear-side plate  303  are inclined at different angles, the first feeding roller pair  201  and the second feeding roller pair  206  cause a difference between the position where these feeding roller pairs are supported by the front-side plate  302  and the position where these feeding roller pairs are supported by the rear-side plate  303  with respect to the vertical direction and the left-right direction. In this case, in the first feeding roller pair  201 , the parallel state between the steel shaft  211   a  supporting the silicone rubbers  211   b  and the rotation shaft of the rollers  212  is collapsed. 
     That is, the first feeding roller pair  201  is in the state in which the parallel state between the rotation shafts of the associated rotatable members is collapsed and in a state in which parallelism therebetween is low. Similarly, the second feeding roller pair  206  is also in the state in which the parallel state between the rotation shafts of the associated rotatable members is collapsed and in the state in which the parallelism therebetween is low. 
     Further, as in this embodiment, in the case where the length of the associated side plate with respect to the vertical direction is longer than the length of the side plate with respect to the widthwise direction which is the sheet feeding direction, these problems occur more conspicuously. Specifically, the positions where the first feeding roller pair  201  and the second feeding roller pair  206  are supported for forming the feeding passage are separated from the position of the bottom plate  301 , and therefore, a deviation amount between the positions where the first feeding roller pair  201  and the second feeding roller pair  206  are supported becomes larger than a positional deviation amount between the front end portion and the rear end portion of the bottom plate  301 . 
     That is, in the case where the bottom plate  301  is inclined, positional deviation between the front-side plate  302  and the rear-side plate  303  at the positions corresponding to the feeding passage with respect to the vertical direction occurs in an amount larger than positional deviation therebetween at the front end portion of the bottom plate  301 , so that a difference in inclination between the positions corresponding to the feeding passage with respect to the vertical direction becomes large. 
     For example, in the case where the flatness of the bottom plate  301  is 0.8, heights of the front end portion and the rear end portion of the bottom plate  301  are deviated from each other so that positions of horizontals formed in the front-side plate  302  and the rear-side plate  303  for supporting the rotation shaft of the first feeding roller pair  201  are deviated from each other by about 2.2 mm. Thus, the positions of the horizontals for supporting the rotation shaft of the first feeding roller pair  201  are deviated between the front and rear side plates, so that the steel shaft  211   a  and the rotation shaft of the rollers  212  are in a distorted state (in which the parallelism is low) so that these shafts cross each other. By this, when the rotation shaft of the rotatable members of the first feeding roller pair  201  are in the distorted state, the sheet S is fed in a largely curved manner. That is, the sheet S fed by the first feeding roller pair  201  was obliquely moved in some cases. 
     Thus, in the image forming system  100  including the inspecting device  102 , although the image formation originally on the sheet S by the image forming apparatus  101  is the same as the image acquired as the reference image, this image is discriminated as an image different from the reference image by the discriminating portion, so that there was a liability that the image is discriminated as a defective (inconvenient) image. 
     Therefore, in this embodiment, a constitution of the supporting frame  300  capable of suppressing occurrence of a difference in angle with respect to an inclination direction and the vertical direction between the pair of side plates consisting of the front-side plate  302  and the rear-side plate  303  supporting the inner units even in the case where the inclination such as the warpage or the distortion of the bottom plate  301  will be described. 
     First, the front-side plate  302  in this embodiment will be described using  FIGS.  5  and  6   .  FIG.  5    is a sectional view showing a relationship between the bottom plate  301  and the front-side plate  302  in  FIG.  3   . Parts (a) and (b) of  FIG.  6    are perspective views of the front-side plate  302 , in which part (a) shows the front-side plate  302  as viewed from a first bent and erected portion  321  side, and part (b) shows the front-side plate  302  as viewed from a second bent and erected portion  322  side. 
     The bottom plate  301  is provided with a first bent and erected portion  301   a  and a second bent and erected portion  301   b  on opposite sides with respect to the widthwise direction, of the inspecting device  102 , which is the sheet feeding direction. Each of the first bent and erected portion  301   a  and the second bent and erected portion  301   b  is formed by being bent and erected substantially perpendicular to a bottom portion  301   c.    
     The front-side plate  302  is constituted so as to include front-side surface portion  320  and the first bent and erected portion  321  and the second bent and erected portion  322  which are bent and erected substantially perpendicular to the front-side portion  320 . Further, the front-side surface portion  320  of the front-side plate  302  is provided with a projected portion  320   a  projected downward with respect to the vertical direction than lower end portions of the first bent and erected portion  321  and the second bent and erected portion  322  are. Further, the projected portion  320  of the front-side surface portion  320  is constituted so as to contact the bottom portion  301   c  at a contact portion H. That is, with respect to a plate thickness direction of the bottom portion  301   c  of the bottom plate  301 , the projected portion  320   a  contacts a surface of the bottom plate  301  on a side opposite from a surface of the bottom plate  301  on which the casters  308  are mounted. 
     Further, as shown in  FIGS.  5  and  6   , the projected portion  320   a  has a substantially V-shape. Here, the substantially V-shape includes are having a free end portion (lower end portion) which has an arcuate shape, not an acute-angled shape as shown in these figures. The shape of the free end portion of the projected portion  320   a  in this embodiment is the arcuate shape of 18.4 mm in radius of curvature. 
     The front-side plate  302  is positioned between the first bent and erected portion  301   a  and the second bent and erected portion  301   b , and the first bent and erected portion  321  is fixed to the first bent and erected portion  301   a  and the second bent and erected portion  322  is fixed to the second bent and erected portion  301   b , so that the front-side plate  302  is fixed to the bottom plate  301 . 
     Here, in a state in which the front-side plate  302  is fixed to the bottom plate  301 , a contact point between the bottom portion  301   c  of the bottom plate  301  and the front-side plate  303  is only the contact portion H. That is, the front-side plate  301  point-contacts the bottom portion  301   c  at the contact portion H. Therefore, the lower end portion (first end portion) of the first bent and erected portion  321  with respect to the vertical direction and the bottom portion  301   c  do not contact each other, so that a gap M is formed between the lower end portion (first end portion) of the first bent and erected portion  321  with respect to the vertical direction and the bottom portion  301   c.    
     Further, the lower end portion (second end portion) of the second bent and erected portion  322  with respect to the vertical direction and the bottom portion  301   c  do not contact each other, so that a gap N is formed between the lower end portion (second end portion) of the second bent and erected portion  322  with respect to the vertical direction and the bottom portion  301   c . Here, in this embodiment, each of the gaps M and N is about 1.0 mm. That is, as shown in  FIG.  6   , with respect to a direction in which a bending edge line formed between the front-side portion  320  of the front-side plate  302  and the first bent and erected portion  321  extends, the lower end portions of the first bent and erected portion  321  and the second bent and erected portion  322  are positioned above the projected portion  320   a . Further, with respect to a direction in which a bending edge line formed between the front-side surface portion  320  and the second bent and erected portion  322  extends, the lower end portions of the first bent and erected portion  321  and the second bent and erected portion  322  are positioned above the projected portion  320   a . In other words, with respect to the direction in which the bending edge line formed between the front-side surface portion  320  and the first bent and erected portion  321  extends, the projected portion  320   a  projects in a downward direction (direction toward the bottom portion  301   c  of the bottom plate  301 ) than the first bent and erected portion  321  and the second bent and erected portion  322  are. 
     Further, in a state before the front-side plate  302  and the bottom plate  301  are fixed to each other, with respect to the widthwise direction of the inspecting device  102  and the supporting frame  300 , a gap E is formed between the first bent and erected portion  321  of the front-side plate  302  and the first bent and erected portion  301   a  of the bottom plate  301 . Further, in this state, a gap D is formed between the second bent and erected portion  322  of the front-side plate  302  and the second bent and erected portion  301   b  of the bottom plate  301 . Here, in this embodiment, each of the gaps D and E is about 0.3 mm. 
     Thus, between the front-side plate  302  and the bottom plate  301 , the gaps M, N, D and E are provided, and therefore, in the state before the front-side plate  302  and the bottom plate  301  are fixed to each other, the front-side plate  302  is swingable about the contact portion H in an arrow W direction. That is, the projected portion  320   a  of the front-side plate  302  is provided at a substantially central portion of the front-side plate  302  with respect to the widthwise direction (angle LR direction). For this reason, the front-side plate  302  is swingable about the substantially central portion with respect to the widthwise direction in the state before being fixed to the bottom plate  301 . 
     Here, the above-described point contact between the front-side plate  302  and the bottom plate  301  at the contact portion H is contact in a degree such that the front-side plate  302  is swingable in the arrow W direction in the state before being fixed to the bottom plate  301 , and does not include line contact or the like such that the front-side plate  302  cannot be swung relative to the bottom plate  301 . 
     As shown in part (a) of  FIG.  6   , a first slit  321   a  is formed between the front-side surface portion  320  and the first bent and erected portion  321 . Further, as shown in part (b) of  FIG.  6   , a second slit  321   a  is formed between the front-side surface portion  320  and the second bent and erected portion  322 . 
     The front-side plate  302  is fixed to the bottom plate  301  with unshown screws inserted in a plurality of first through hole  321   b  formed in the first bent and erected portion  321  and a plurality of second through holes  322   b  formed in the second bent and erected portion  322 . Here, the plurality of first through holes  321   b  and the plurality of second through holes  322   b  are top holes for fixing the unshown screws. Here, a flat surface in which the first through holes  321   b  are formed is an example of a first fixing surface, and a flat surface in which the second through holes  322   b  are formed is an example of a second fixing surface. Further, the front-side surface portion  320  is an example of a first supporting surface portion for supporting one end side of the inner units, the first bent and erected portion  321  is an example of the first fixing surface, and the second bent and erected portion  322  is an example of the second fixing surface. 
     A structure and an assembling procedure of the supporting frame using the thus-constituted front-side plate  302  and bottom plate  301  will be described. 
       FIG.  7    is a perspective view showing a state in which a rear-side plate right-angled jig  900  is mounted on the bottom plate  301 . The rear-side plate right-angled jig  900  includes a triangular right-angled frame  901 , and a first horizontal frame  902 , a second horizontal frame  903  and a third horizontal frame  904  which extend in the horizontal direction. The right-angled frame  901  is provided with pins  905  and  906  which project toward the bottom plate  301  and engage in positioning holes  301   ca  and  301   cb , respectively, formed in the bottom portion  301   c  of the bottom plate  301 . Here, the positioning hole  301   ca  has a size such that the pin  905  is engageable therein and positioning thereof with respect to the horizontal direction can be carried out. Incidentally, the positioning hole  301   cb  is an elongated hole extending in the front-rear direction of the supporting frame  300  and is capable of positioning the pin  906  with respect to the left-right direction of the supporting frame  300 . 
     Incidentally, the rear-side plate right-angled jig  900  includes a plurality of magnets  908  mounted on the first horizontal frame  902  and a plurality of magnets  909  mounted on the second horizontal frame  903 . In this embodiment, three magnets  908  and two magnets  909  are provided. Further, the plurality of magnets  908  and  909  attract the rear-side plate  303 , so that the rear-side plate  303  is held perpendicular to the bottom portion  301   c  of the bottom plate  301 . That is, by the rear-side plate right-angled jig  900 , a perpendicular state between the rear-side plate  303  and the bottom plate  301  can be ensured. 
     Further, the third horizontal frame  904  is provided with a plurality of magnets  910  mounted thereon, and the magnets  900  attract the front-side plate  302 , so that the front-side plate  302  can be positioned relative to the bottom plate  301 . 
       FIG.  9    shows a state in which the rear-side plate  303  is mounted on the structure shown in a state of  FIG.  7   . The rear-side plate  303  includes a perpendicular surface portion  303   a  in which supporting holes for supporting the inner units are formed, side surface portions  303   b  and  303   c  substantially bent and erected from the perpendicular surface portion  303   a , and a bottom portion  303   d  substantially bent and erected from the perpendicular surface portion  303   a  and the side surface portions  303   b  and  303   c . In a state shown in  FIG.  8   , the fine magnets in total of the plurality of magnets  908  and  909  shown in  FIG.  7    attract the perpendicular surface portion  303   a  of the rear-side plate  303 , so that the rear-side plate  303  is held substantially perpendicular to the bottom plate  301 . Incidentally, the perpendicular surface portion  303   a  is an example of a second supporting surface portion supporting the inner units on the other end side, and the bottom portion  303   d  is an example of a bottom fixing portion. 
     Further, in a state in which the rear-side plate  303  is held by the rear-side plate right-angled jib  900 , the rear-side plate  303  is fastened with screws  309 , so that the bottom portion  303   d  of the rear-side plate  303  and the bottom portion  301   c  of the bottom plate  301  are fixed to each other. Thereafter, the rear-side plate  303  is fastened with screws  310 , so that the first bent and erected portion  301   a  and the second bent and erected portion  301   b  of the bottom plate  301  and the side surface portion  303   b  and the side surface portion  303   c  of the rear-side plate  303  are fixed, respectively, to each other. By this, the rear-side plate  303  is fixed to the bottom plate  301  in a state in which a right-angled state thereof is ensured. 
       FIG.  9    shows a state in which the front-side plate  302 , the right rail stay  304  and the left rail stay  305  are mounted on the structure shown in  FIG.  8   . In the state of  FIG.  9   , the rear-side plate  302  and each of the right rail stay  304  and the left rail stay  305  are fixed to each other by being fastened with unshown screws. Incidentally, in the state of  FIG.  9   , the front-side plate  302  is not fixed to the bottom plate  301 , and a state in which the bottom portion  301   c  of the bottom plate  301  and the projected portion  320   a  are in a contact state with each other at the contact portion H in a state in which the front-side plate  302  is held by the plurality of magnets  910  is formed. 
     Here, the rear-side plate  303  is provided with jig inserting holes  350  and  351  at an upper portion thereof. Here, the jig inserting hole  350  is a through hole having a circular shape, and the jig inserting hole  351  is a through hole having an elongated shape extending in the sheet feeding direction (widthwise direction of the inspecting device  102 ). Further, the front-side plate  302  is provided with a jig inserting hole  352  at an upper portion thereof. Here, the jig inserting hole  352  is a through hole having a circular shape. 
       FIG.  10    shows a front-side plate positioning jig  120 . The front-side plate positioning jig  120  is provided with pins  121 ,  122  and  123 . Each of these pins  121 ,  122  and  123  is provided with satisfactory right-angled accuracy. That is, the pins  121 ,  122  and  123  are arranged so that a phantom line connecting the pins  121  and  122  and a phantom line connecting the pins  121  and  123  are perpendicular to each other. Further, the pins  121  and  122  are engaged in the positioning holes  350  and  351 , respectively, provided at the upper portion of the rear-side plate  303  shown in  FIG.  9   , and the pin  123  is engaged in the positioning hole  352  provided at the upper portion of the front-side plate  302  shown in  FIG.  9   . 
       FIG.  11    shows a state in which the front-side plate positioning jig  120  is set on the structure shown in  FIG.  9   . 
     By the front-side plate positioning jig  120 , the position of the front-side plate  302  can be adjusted on the basis of the rear-side plate  303  fixed to the bottom plate  301 . That is, in the state in which the front-side plate positioning jib  120  is mounted, the front-side plate  302  swings about the contact portion H, as a rotation center, between the projected portion  320   a  and the bottom plate  301  in the arrow W direction shown in  FIG.  5    relative to the bottom plate  301  and the rear-side plate  303  as described with reference to  FIG.  6   . 
     Thus, the front-side plate  302  is swung relative to the bottom plate  301  and the rear-side plate  303 , whereby inclination of the front-side plate  302  relative to the rear-side plate  303  can be adjusted. Thus, by adjusting the inclination of the front-side plate  302  relative to the rear-side plate  303  fixed in a state in which the rear-side plate  303  is maintained in a right-angled state with the bottom plate  301  by the rear-side plate right-angled jig  900 , adjustment can be made so that inclination directions and inclination angles of the front-side plate  302  and the rear-side plate  303  are equal to each other, respectively. 
     Further, in a state in which the inclination direction and angle of the front-side plate  302  relative to the rear-side plate  303  are adjusted, the front-side plate  302  and the bottom plate  301  are fixed to each other by being fastened with screws. Specifically, the first bent and erected portion  321  of the front-side plate  302  and the first bent and erected portion  301   a  of the bottom plate  301  are fixed by screws  131 , and the second bent and erected portion  322  of the front-side plate  302  and the second bent and erected portion  301   b  of the bottom plate  301  are fixed by screws  131 . By this, the front-side plate  302  is fixed to the bottom plate  301  in a state in which positional deviation between the front and rear side plates  302  and  303  caused due to differences in inclination direction and inclination angle of the front-side plate  302  relative to the rear-side plate  303  is suppressed. 
     Then, the front-side plate  302  and each of the right rail stay  304  and the left rail stay  305  are fixed to each other by being fastened with screws. 
     In this embodiment, a constitution in which when the bottom plate  301  and the front-side plate  302  are fixed to each other with the screws, these plates are fixed by the screws with respect to only the horizontal direction is employed. That is, the front-side plate  302  is not directly fastened to the bottom portion  301   c  of the bottom plate  301 , but is fastened to only the first bent and erected portion  301   a  and the second bent and erected portion  301   b . This is because when the front-side plate  302  is directly fixed to the bottom portion  301   c  of the bottom plate  301 , in the case where inclination such as warpage or distortion generates in the bottom plate  301 , the inclination of the bottom plate  301  has the influence on the fixing of the front-side plate  302  on the bottom plate  301  and thus it is required that inclination of the front-side plate  302  relative to the rear-side plate  303  is suppressed. 
     Incidentally, as described above with reference to  FIGS.  5  and  6   , with respect to the widthwise direction of the inspecting device  102  and the supporting frame  300 , the gap E is provided between the first bent and erected portion  321  of the front-side plate  302  and the first bent and erected portion  301   a  of the bottom plate  301 . Further, in this state, the gap D is provided between the second bent and erected portion  322  of the front-side plate  302  and the second bent and erected portion  301   b  of the bottom plate  301 . Further, the slit  321   a  is formed between the front-side surface portion  320  and the first bent and erected portion  321  of the front-side plate  302 , the slit  322   a  is formed between the front-side surface portion  320  and the second bent and erected portion  322  of the front-side plate  302 . By this, in the case where the front-side plate  302  and the bottom plate  301  are fixed with the screws, a constitution in which the first bent and erected portion  321  and the second bent and erected portion  322  of the front-side plate  302  are fixed to the first bent and erected portion  301   a  and the second bent and erected portion  301   b  of the bottom plate  301 , respectively, by flexing or bending free end-side regions where the slits  321   a  and  322   a  are formed with respect to the vertical direction is employed. Thus, by providing the slits  321   a  and  322   a , even in a constitution in which the above-described gaps D and E are formed between the front-side plate  302  and the bottom plate  301 , each of free end portions of the first bent and erected portion  321  and the second bent and erected portion  322  can be flexed by a fastening force of the screws when the front-side plate  302  and the bottom plate  301  are fastened with the screws, and therefore, the front-side plate  302  and the bottom plate  301  can be easily fastened to each other. 
       FIG.  12    shows the supporting frame  300  in a state in which the front-side plate positioning jig  120  and the rear-side plate right-angled jig  900  are dismounted, and shows a state in which the link stays  306  and the stays  307  are fixed to each of the front-side plate  302  and the rear-side plate  303 . Incidentally,  FIG.  12    shows a state in which the supporting frame  300  of the inspecting device  102  is completed. 
     As described above, the front-side plate  302  is not directly fixed to the bottom portion  301   c  of the bottom plate  301 , and therefore, even in the case where the inclination such as the warpage or the distortion generates in the bottom portion  301   c , the influence of the inclination of the bottom portion  301   c  is not readily exerted on the front-side plate  302 . 
     Further, the front-side plate  302  is fixed to the first bent and erected portion  301   a  and the second bent and erected portion  301   b  of the bottom plate  301  in a state in which the inclination direction and the inclination angle thereof relative to the rear-side plate  303  and adjusted, and therefore, it is possible to suppress that the inclination direction and the inclination angle are different between the front-side plate  302  and the rear-side plate  303  by the influence of the flatness of the bottom plate  301 . 
     Further, thus it is possible to suppress that the inclination direction and the inclination angle are different between the front-side plate  302  and the rear-side plate  303 , and therefore, it is possible to suppress that the inner units supported by each of the front-side plate  302  and the rear-side plate  303  are supported in an inclined state. Therefore, it is possible to suppress that a distance between a position where the first feeding roller pair  201  and the second feeding roller pair  206  are supported by the front-side plate  302  and a position where the first feeding roller pair  201  and the second feeding roller pair  206  are supported by the rear-side plate  303  is caused with respect to each of the vertical direction and the left-right direction. That is, it is possible to suppress that the hole positions for supporting the rotation shaft of the first feeding roller pair  201  provided in the front-side plate  302  and the rear-side plate  303  are deviated from each other and thus the rotation shaft is in a distorted state (state in which the parallelism is low) so that the steel shaft  211   a  and the rotation shaft of the rollers  212  cross each other. As a result, oblique movement of the sheet fed by the first feeding roller pair  201  can be suppressed. Accordingly, in the image forming system  100  including the above-described inspecting device  102 , it is possible to suppress that although the image formed originally on the sheet by the image forming apparatus  101  is the same as the image acquired as the reference image, the image is discriminated as an image different from the reference image by the discriminating portion and is classified as a defective image. 
     Second Embodiment 
     Next, a second embodiment will be described using  FIG.  13   . Incidentally, in the second embodiment, constituent elements are similar to those in the first embodiment except that the fixing position of the front-side plate  302  relative to the bottom plate  301  is different from that in the first embodiment, and therefore, are represented by the same reference numerals or symbols and will be omitted from description. 
     In the second embodiment, a fixing-metal plate  1500  for fixing the front-side plate  302  to the bottom plate  301  is provided. The fixing metal plate  1500  is fixed to the bottom plate  301  by being fastened to the bottom plate  301  with screws. 
     Further, similarly as in the first embodiment, the front-side plate  302  is adjusted in inclination direction and inclination angle relative to the rear-side plate  303 , and thereafter is fixed to the fixing plate  1500  by being fastened with screws  1501 . 
     Also, in this constitution, similarly as in the first embodiment, the front-side plate  302  contacts the bottom portion  301   c  of the bottom plate  301  by the projected portion  320   a  of the front-side surface portion  320 , but the first bent and erected portion  321  and the second bent and erected portion  322  do not contact the bottom portion  301   c . By this constitution, the front-side plate  302  is capable of swinging about the contact point H between the projected portion  320   a  and the bottom portion  301   c  in the arrow W direction (see  FIG.  5   ), so that adjustment of inclination of the front-side plate  302  relative to the rear-side plate  303  by using the jigs is easily performed. 
     Further, the front-side plate  302  subjected to the adjustment of the inclination direction and the inclination angle relative to the rear-side plate  303  can be fixed to the bottom plate  301  by the fixing plate  1500 , and therefore, it is possible to suppress that there arises a difference in inclination direction and inclination angle between the front-side plate  302  and the rear-side plate  303 . At this time, of mounting holes through which the screws  1501  are inserted, either one of the mounting holes of the fixing metal plate  1500  and the front-side plate  302  is provided as an elongated hole, so that the front-side plate  302  after the angle adjustment is performed can be fixed to the fixing metal plate  1500 . 
     Thus, also in the second embodiment, the front-side plate  302  is not directly fixed to the bottom portion  301   c  of the bottom plate  301  but is fixed to the bottom portion  301   c  through the fixing metal plate  1500 , and therefore, even in the case where the inclination such as the warpage or the distortion generates in the bottom plate  301 , it is possible to suppress that the front-side plate  302  is influenced by the inclination of the bottom plate  301 . 
     Other Embodiments 
     In the above-described embodiments, the constitution in which the front-side plate  302  is adjusted in accordance with the inclination direction and the inclination angle of the rear-side plate  303  was described, but by employing the constitutions of the above-described embodiments, a constitution in which the rear-side plate  303  is adjusted in accordance with the inclination direction and the inclination angle of the front-side plate  302  may also be employed. In this case, the constitution may only be required that the front-side plate  302  is first fixed to the bottom plate  301  by using the jig  900  and the like. 
     Further, in the above-described embodiments, the free end portion shape of the projected portion  320   a  provided as the part of the front-side plate  302  was the substantially V-shape, but a constitution in which the projected portion  320   a  has a V-shape with an acute tip may also be employed when the projected portion  320   a  point-contacts the bottom portion  301   c  of the bottom plate  301 . Further, the radius of curvature is not limited to the above-described radius of curvature when a constitution in which the projected portion  320   a  of the front-side surface portion  320  point-contacts the bottom portion  301   c  of the bottom plate  301  is employed. Even in this case, as described above, the projected portion  320   a  point-contacts the bottom portion  301   c  of the bottom plate  301  and thus the front-side plate  302  can swing relative to the bottom plate  301 , so that the position of the front-side plate  302  relative to the rear-side plate  303  can be adjusted. 
     Further, in the above-described embodiments, the constitution in which in the state before the front-side plate  302  is fixed to the bottom plate  301 , the gap M is formed between the bottom portion  301   c  and the lower end portion of the first bent and erected portion  321  with respect to the vertical direction is formed and the gap N is formed between the bottom portion  301   c  and the lower end portion of the second bent and erected portion  322  with respect to the vertical direction is formed was employed. In this constitution, in a state in which the front-side plate  302  and the bottom plate  301  are fixed to each other after the inclination direction and the inclination angle between the front-side plate  302  and the rear-side plate  303  are adjusted, the gaps M and N change. In design, when a constitution in which either one of the gaps M and N is 0 is employed, an adjustment range is narrowed, and therefore, in the state in which the front-side plate  302  and the bottom plate  301  are fixed to each other, it is desired that a constitution in which both the gaps M and N are not 0 is employed. However, when a constitution in which the front-side plate  302  is swingable relative to the bottom plate  301  and the adjustment of the front-side plate  302  relative to the rear-side plate  303  is sufficiently enabled is employed, a constitution in which either one of the gaps M and N is 0 in the state in which the front-side plate  302  and the bottom plate  301  are fixed to each other may also be employed. 
     Incidentally, in the above-described embodiments, the constitution in which the component parts of the supporting frame  300  are fixed by being fastened with the screws was employed, but another fixing method such as laser welding may also be employed. In this case, the gaps D and E provided between the front-side plate  302  and the bottom plate  301  are set at intervals in which the laser welding is enabled, so that the front-side plate  302  and the bottom plate  301  can be fixed to each other by the laser welding. 
     Incidentally, in the above-described embodiments, the constitution of the supporting frame  300  of the inspecting device  102  including the feeding roller pairs and the reading units such as the CIS units, as the inner units was described, but the constitutions of the above-described embodiments may also be applied to a supporting frame of another device or apparatus. For example, to a supporting frame of a sheet feeding device for feeding the sheet, such as a decurler device for rectifying a curl of the sheet, the constitution of the above-described supporting frame  300  may also be applied. Even in this case, it is possible to suppress that parallelism between the rotation shafts of the rotatable members becomes poor due to the difference in inclination direction and inclination angle between the front-side plate  302  and the rear-side plate  303  of the supporting frame  300 . Accordingly, it is possible to suppress the oblique movement of the sheet fed by the feeding roller pair in the sheet feeding device. 
     According to the present invention, it is possible to provide the supporting frame of the sheet feeding device capable of improving accuracy of relative position between the pair of side plates. 
     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. 
     This application claims the benefit of Japanese Patent Applications Nos. 2020-033881 filed on Feb. 28, 2020 and 2020-195549 filed on Nov. 25, 2020, which are hereby incorporated by reference herein in their entirety.