Abstract:
An image formation apparatus comprising: a belt member suspended by a plurality of supporting rotating bodies and thus rotating; a cleaning member removing toner adhering to the belt member; a tray receiving waste toner removed from the belt member by the cleaning member; a vibration mechanism vibrating the tray to move the waste toner toward a lower side of the tray; a steering control mechanism to perform movement control to move the belt member in an axial direction of the supporting rotating bodies while the belt member rotates; and a vibration adjustment mechanism to change a manner of vibration of the vibration mechanism, based on the movement control by the steering control mechanism.

Description:
[0001]    This application is based on Japanese Patent Application No. 2015-240281 filed with the Japan Patent Office on Dec. 9, 2015, the entire content of which is hereby incorporated by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    Field of the Invention 
         [0003]    The present invention relates to an image formation apparatus and particularly to an image formation apparatus having a steering control function. 
         [0004]    Description of the Related Art 
         [0005]    An image formation apparatus includes around an image carrier a charging device, an exposure device, a developer, a transfer device, a cleaning device, a diselectrifying lamp, etc. The charging device charges the image carrier uniformly. Subsequently, the exposure device forms an electrostatic latent image on the image carrier. The developer develops the electrostatic latent image into a toner image. The transfer device transfers the toner image to a transported transferring material. The cleaning device removes residual toner on the image carrier. The diselectrifying lamp removes the electric charge of the image carrier. Image formation is performed by this series of steps. 
         [0006]    In the image formation, an endless belt may be used as the image carrier or an intermediate transfer body. The endless belt (hereinafter also simply referred to as a “belt”) is tensioned and thus engaged on a plurality of rollers having at least a drive roller and a tensioning roller, and thus driven. 
         [0007]    However, depending on the rollers&#39; parallelism accompanying their arrangement, the rollers&#39; precision as a cylinder, a difference between the opposite lateral edges of the belt in circumferential length, etc., there is a possibility that a phenomenon occurs in which the belt moves in a direction having a right angle relative to the direction of transportation (i.e., in the roller&#39;s axial direction), i.e., the belt meanders. 
         [0008]    When the meandering phenomenon occurs, an image which is formed on the belt or an image which is transferred on the belt is offset and a satisfactory image cannot be obtained. 
         [0009]    Accordingly, Japanese Laid-Open Patent Publication No. 6-56294 proposes, as a technique to control the meandering of the belt, an intermediate transfer unit which has a steering control function to control the belt&#39;s axial movement by moving one end of a roller that imparts tension to the belt to vary a distance which the belt&#39;s end travels. 
         [0010]    Furthermore, Japanese Laid-Open Patent Publication No. 2009-31613 proposes a system in which, in an intermediate transfer unit having a steering control function, in order to remove residual toner on an intermediate transfer belt, a cleaning blade abuts against the intermediate transfer belt. 
       SUMMARY OF THE INVENTION 
       [0011]    However, in the system in which the cleaning blade abuts against the intermediate transfer belt, waste toner scraped off remains on a toner tray. When the waste toner which remains on the toner tray is accumulated, there is a possibility that the waste toner may return to the intermediate transfer belt and smear an image, and accordingly, the waste toner needs to be removed as appropriate. Accordingly, there is provided a mechanism for vibrating the toner tray, as timed in a fixed manner, to collect waste toner to obtain a stable output image. 
         [0012]    However, in the intermediate transfer unit which has the steering control function, when the position of the intermediate transfer roller is moved by steering control, the cleaning blade abuts against the belt in a varying amount (or with a varying pressure). This variation may vary the amount of toner scraped off by the cleaning blade and accordingly increase the amount of waste toner. As such, it is necessary to adjust the waste toner collection system according to the steering control, however, this is not considered in any of the above documents. 
         [0013]    The present invention has been made to address the above issue, and contemplates an image formation apparatus having a steering control function, that can obtain a stable output image, and a method of controlling the image formation apparatus. 
         [0014]    To achieve at least one of the above mentioned objects an image forming apparatus reflecting one aspect of the present invention comprises: a belt member suspended by a plurality of supporting rotating bodies and thus rotating; a cleaning member removing toner adhering to the belt member; a tray receiving waste toner removed from the belt member by the cleaning member; a vibration mechanism vibrating the tray to move the waste toner toward a lower side of the tray; a steering control mechanism to perform movement control to move the belt member in an axial direction of the supporting rotating bodies while the belt member rotates; and a vibration adjustment mechanism to change a manner of vibration of the vibration mechanism, based on the movement control by the steering control mechanism. 
         [0015]    Preferably, the vibration adjustment mechanism changes as the manner of vibration at least any one of a vibration frequency and a vibration amplitude applied to vibrate the tray. 
         [0016]    Preferably, the vibration adjustment mechanism changes the manner of vibration of the vibration mechanism based on at least any one of the movement control by the steering control mechanism, an image writing region&#39;s size, an image writing density, and an amount travelled by the belt member. 
         [0017]    Preferably, the vibration mechanism includes an impinging member to impinge on the tray, with a fulcrum position serving as a fulcrum, to vibrate the tray. The vibration adjustment mechanism adjusts the impinging member&#39;s fulcrum position. 
         [0018]    Preferably, the steering control mechanism includes a cam to adjust at least one of the plurality of supporting rotating bodies positionally, and a motor for driving the cam to perform the movement control. The vibration adjustment mechanism includes a moving roller provided movably to set a fulcrum position, and at least one gear coupled between the moving roller and the motor for moving the moving roller as the motor is driven. 
         [0019]    According to one aspect, a method for controlling an image formation apparatus having a belt member suspended by a plurality of supporting rotating bodies and thus rotating, a cleaning member removing toner adhering to the belt member, and a tray receiving waste toner removed from the belt member by the cleaning member, the method comprising: imparting vibration to the tray to move waste toner toward a lower side of the tray; performing movement control to move the belt member in an axial direction of the supporting rotating bodies while the belt member rotates; and changing a manner of vibration, based on the movement control, to impart vibration. 
         [0020]    The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]      FIG. 1  is a diagram schematically showing a general configuration of an image formation apparatus  1  based on an embodiment. 
           [0022]      FIG. 2  is a diagram illustrating a configuration of a mechanism in a vicinity of an intermediate transfer belt  421  based on an embodiment. 
           [0023]      FIGS. 3A and 3B  are diagrams illustrating a cleaning state accompanying a steering control based on an embodiment. 
           [0024]      FIG. 4  illustrates a configuration of a steering control mechanism and a belt cleaning device  426  based on an embodiment. 
           [0025]      FIG. 5  illustrates a configuration of a vibration mechanism  8  and a vibration adjustment mechanism  9  based on an embodiment. 
           [0026]      FIG. 6  illustrates a flow of printing control of image formation apparatus  1  based on an embodiment. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    An embodiment will now be described in detail with reference to the drawings. In the figures, identical or corresponding components are identically denoted and will not be described repeatedly. 
         [0028]    &lt;A. Outline of General Configuration&gt; 
         [0029]      FIG. 1  is a diagram schematically showing a general configuration of an image formation apparatus  1  based on an embodiment. 
         [0030]    With reference to  FIG. 1 , image formation apparatus  1  is a color image formation apparatus of an intermediate transfer system utilizing electrophotography process technology. More specifically, image formation apparatus  1  transfers color toner images of Y (yellow), M (magenta), C (cyan), and K (black), respectively, each formed on a photoreceptor drum  413 , to an intermediate transfer belt  421  (i.e., primary transfer) to superimpose the toner images of the 4 colors, one on another, on intermediate transfer belt  421 , and subsequently transfers the superimposed toner images to a sheet S (i.e., secondary transfer) to form an image. 
         [0031]    Furthermore, image formation apparatus  1  adopts a tandem system in which photoreceptor drums  413  corresponding to the 4 colors of YMCK are disposed in series in a direction in which intermediate transfer belt  421  travels to allow each color toner image to be transferred to intermediate transfer belt  421  successively through a single procedure. 
         [0032]    Image formation apparatus  1  includes an image reading portion  10 , an operation and display portion  20 , an image processing portion  300 , an image forming portion  400 , a sheet transport portion  500 , a fixing portion  60 , and a control portion  100 . 
         [0033]    Control portion  100  includes a CPU (Central processing unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The CPU reads a program depending on the contents to be processed from the ROM and develops it in the RAM, and cooperates with the developed program to intensively control an operation of each block of image formation apparatus  1 . 
         [0034]    Image reading portion  10  is configured including an automatic original sheet feeding device  11  referred to as an ADF (Auto Document Feeder), and an original image scanning device  12  (a scanner), etc. 
         [0035]    Automatic original sheet feeding device  11  transports an original that is placed on an original tray by a transport mechanism, and sends it out to original image scanning device  12 . Automatic original sheet feeding device  11  can read at once successively images on a large number of originals (including opposite sides) placed on the original tray. 
         [0036]    Original image scanning device  12  optically scans an original transported to a contact glass from automatic original sheet feeding device  11  or an original placed on the contact glass, forms an image of the light that is reflected from the original on a light receiving surface of a CCD (Charge Coupled Device) sensor  12   a,  and reads the original&#39;s image. Image reading portion  10  generates input image data based on a result of reading by original image scanning device  12 . This input image data is subjected to a prescribed image processing in image processing portion  300 . 
         [0037]    Operation and display portion  20  is configured for example by a touchscreen panel equipped liquid crystal display (LCD) and functions as a display portion  221  and an operation portion  222 . Display portion  221  operates in response to a display control signal received from control portion  100  to display various types of operation screens, a state of an image, how each function operates, etc. Operation portion  222  includes various types of operation keys, such as numerical keys and a start key etc. and receives a variety of types of input operations done by the user and outputs an operation signal to control portion  100 . 
         [0038]    Image processing portion  300  includes a circuit etc. which subjects input image data to digital image processing depending on an initial setting or a user setting. For example image processing portion  300  is controlled by control portion  100  to perform gray level correction based on gray level correction data (a gray level table). Furthermore, image processing portion  300  subjects input image data to gray level correction, and other than that, color correction, shading correction and other various types of correction processes, a compression process etc. Image forming portion  400  is controlled based on the image data that has underwent these processes. 
         [0039]    Image forming portion  400  includes image forming units  41 Y,  41 M,  41 C,  41 K operative in response to input image data for forming an image by each colored toner of a Y component, an M component, a C component, and a K component, an intermediate transfer unit  42 , etc. 
         [0040]    Image forming units  41 Y,  41 M,  41 C,  41 K for the Y component, the M component, the C component and the K component have a similar configuration. For the sake of illustration and description, common components are identically denoted and when they are distinguished they are denoted by identical reference characters with a letter Y, M, C, or K attached thereto. In  FIG. 1 , only image forming unit  41 Y for the Y component has its constituent components denoted by reference characters and the other image forming units  41 M,  41 C,  41 K have their constituent components undenoted by reference characters. 
         [0041]    Image forming unit  41  includes an exposure device  411 , a developing device  412 , a photoreceptor drum  413 , a charging device  414 , and a drum cleaning device  415  etc. 
         [0042]    Photoreceptor drum  413  is for example a negatively charged organic photoconductor (OPC) having an electrically conductive cylindrical body of aluminum (an elementary tube of aluminum) having a circumferential surface with an undercoat layer (UCL), a charge generation layer (CGL) and a charge transport layer (CTL) successively deposited thereon. The charge generation layer is composed of an organic semiconductor having a charge generating material (e.g., a phthalocyanine pigment) dispersed in a resin binder (e.g., polycarbonate), and is exposed to light by exposure device  411  to generate a pair of a positive charge and a negative charge. The charge transport layer is made of what has a hole transporting material (an electron-donating, nitrogen-containing compound) dispersed in a resin binder (e.g., polycarbonate resin), and transports the positive charge that is generated in the charge generation layer to a surface of the charge transport layer. 
         [0043]    Control portion  100  controls a driving current supplied to a motor (not shown) that causes photoreceptor drum  413  to rotate so that photoreceptor drum  413  rotates at a controlled circumferential speed. 
         [0044]    Charging device  414  charges a surface of photoconductive photoreceptor drum  413  uniformly to have negative polarity. Exposure device  411  is configured for example by a semiconductor laser and exposes photoreceptor drum  413  to laser light corresponding to an image of each color component. The positive charge generated in the charge generation layer of photoreceptor drum  413  and transported to a surface of the charge transport layer neutralizes a charge of a surface of photoreceptor drum  413  (a negative charge). On a surface of photoreceptor drum  413 , an electrostatic latent image of each color component will be formed by a difference in potential from the surroundings. 
         [0045]    Developing device  412  is for example of a two-component development system and allows a toner of each color component to adhere to a surface of photoreceptor drum  413  to visualize an electrostatic latent image to thus form a toner image. 
         [0046]    Drum cleaning device  415  has a drum cleaning blade etc. sliding in contact with a surface of photoreceptor drum  413  to remove toner remaining on a surface of photoreceptor drum  413  after the primary transfer. 
         [0047]    Intermediate transfer unit  42  includes an intermediate transfer belt  421 , a primary transfer roller  422 , a plurality of drive rollers  423 A- 423 D (also collectively referred to as a drive roller  423 ), a secondary transfer roller  424 , and a belt cleaning device  426  etc. 
         [0048]    Intermediate transfer belt  421  is an endless belt and tensioned and thus engaged on the plurality of drive rollers  423  in a loop. At least one of the plurality of drive rollers  423  is a driving roller  423 A and the others are driven rollers. When driving roller  423 A is rotated by control portion  100 , intermediate transfer belt  421  travels in a direction of an arrow A. 
         [0049]    Primary transfer roller  422  is disposed on the side of the inner circumferential surface of intermediate transfer belt  421  opposite to photoreceptor drum  413  of each color component. Primary transfer roller  422  is pressed against photoreceptor drum  413  with intermediate transfer belt  421  sandwiched therebetween to form a primary transfer nip for transferring a toner image from photoreceptor drum  413  to intermediate transfer belt  421 . 
         [0050]    Secondary transfer roller  424  is disposed on the side of the outer circumferential surface of intermediate transfer belt  421 , opposite to drive roller  423 B disposed downstream of drive roller  423 A as seen in a direction in which the belt travels. Secondary transfer roller  424  is pressed against drive roller  423 B with intermediate transfer belt  421  sandwiched therebetween to form a secondary transfer nip for transferring a toner image from intermediate transfer belt  421  to sheet S. 
         [0051]    When intermediate transfer belt  421  passes the primary transfer nip, toner images on the plurality of photoreceptor drums  413  are successively superimposed on intermediate transfer belt  421  and thus primarily transferred. Specifically, a primary transferring bias is applied to primary transfer roller  422  to impart an electric charge having a polarity opposite to that of the toner to the back side of intermediate transfer belt  421  (a side thereof that abuts against primary transfer roller  422 ) to electrostatically transfer the toner image to intermediate transfer belt  421 . 
         [0052]    Subsequently, when sheet S passes the secondary transfer portion, the toner image on intermediate transfer belt  421  is secondarily transferred to sheet S. Specifically, a secondary transferring bias is applied to secondary transfer roller  424  to impart an electric charge having a polarity opposite to that of the toner to the back side of sheet S (a side thereof that abuts against secondary transfer roller  424 ) to electrostatically transfer the toner image to sheet S. Sheet S with the toner image transferred thereon is transported toward fixing portion  60 . 
         [0053]    Thus secondary transfer roller  424  and drive roller  423 B sandwich intermediate transfer belt  421  to thus form a nip portion. Accordingly, drive roller  423 B, secondary transfer roller  424 , and intermediate transfer belt  421  will function as a secondary transfer portion which secondarily transfers to sheet S passing through the nip portion the images that are successively transferred from the plurality of photoreceptor drums  413  to intermediate transfer belt  421 . 
         [0054]    Belt cleaning device  426  has a belt cleaning blade  5  etc. which slides in contact with a surface of intermediate transfer belt  421  to remove toner which remains on a surface of intermediate transfer belt  421  after the secondary transfer portion has done the secondary transfer. 
         [0055]    Note that instead of secondary transfer roller  424 , a configuration may be adopted in which a secondary transfer belt is tensioned and thus engaged in a loop on a plurality of drive rollers including a secondary transfer roller (a so-called belt-type secondary transfer unit). It is needless to say that this case also allows the above secondary transfer roller to be pressed against drive roller  423 B to form a nip portion with intermediate transfer belt  421  sandwiched thereby. 
         [0056]    A belt position detection sensor  251  is provided downstream of belt cleaning device  426 . Steering control by a steering control mechanism described later is performed based on a result of detection done by belt position detection sensor  251 . 
         [0057]    Fixing portion  60  has an upper fixing portion  60 A having a fixing surface side member disposed on the side of a fixing surface of sheet S (i.e., a surface thereof on which a toner image is formed), a lower fixing portion  60 B having a back surface side member disposed on the side of the back surface of sheet S (i.e., a surface thereof opposite to the fixing surface), and a heat source  60 C etc. The back surface side support member is pressed against the fixing surface side member to form a fixing nip portion which pinches and thus transports sheet S. 
         [0058]    Fixing portion  60  receives sheet S that has a toner image secondarily transferred thereon and is thus transported, and fixing portion  60  heats and pressurizes sheet S at the fixing nip portion to fix the toner image on sheet S. Fixing portion  60  is disposed in a fixer F as a unit. Furthermore, in fixer F, an air separating unit may be disposed to blow air to separate sheet S from the fixing surface side member or the back surface side support member. 
         [0059]    Sheet transport portion  500  includes a sheet feeding portion  51 , a sheet discharging portion  52 , and a transport path portion  53 , etc. Sheet feeding portion  51  is composed of three sheet feeding tray units  51   a - 51   c  which accommodate sheets S identified based on paper weight in grams per square meter, size, etc. for each preset type. Transport path portion  53  has a plurality of transport roller pairs, such as a registration roller pair  53   a.    
         [0060]    Sheets S accommodated in sheet feeding tray units  51   a - 51   c  are output one by one from the topmost portion and transported to image forming portion  400  by transport path portion  53 . And in the secondary transfer portion, the toner image on intermediate transfer belt  421  is collectively, secondarily transferred to one surface of sheet S and undergoes a fixing step in fixing portion  60 . Sheet S having an image formed thereon is discharged outside the apparatus by sheet discharging portion  52  including a sheet discharging roller  52   a.    
         [0061]    &lt;B. Configuration of Mechanism in a Vicinity of Intermediate Transfer Belt  421 &gt; 
         [0062]      FIG. 2  is a diagram illustrating a configuration of a mechanism in a vicinity of intermediate transfer belt  421  based on an embodiment. 
         [0063]      FIG. 2  shows belt cleaning device  426  and a steering control device  3  provided in a vicinity of intermediate transfer belt  421 . 
         [0064]    Steering control device  3  detects a positional offset of intermediate transfer belt  421 , and performs movement control based on the detection result to move intermediate transfer belt  421  in the axial direction of drive roller  423 C. 
         [0065]    Steering control device  3  includes belt position detection sensor  251 , a steering control portion  155 , and a steering control mechanism. 
         [0066]    Belt position detection sensor  251  detects a positional offset of intermediate transfer belt  421  and outputs a detection signal to steering control portion  155 . 
         [0067]    Steering control portion  155  generally controls steering control device  3  and calculates an amount of steering based on the detection signal for correcting the positional offset. Steering control portion  155  operates based on the calculated result to control a steering control motor  13  to resolve the positional offset of intermediate transfer belt  421 . 
         [0068]    The steering control mechanism is composed of steering control motor  13 , a gear  14 , and a cam  15 . 
         [0069]    Steering control motor  13  drives gear  14 . Gear  14  is coupled with cam  15  and set such that when gear  14  is driven, cam  15  rotates. 
         [0070]    Belt cleaning device  426  includes belt cleaning blade  5 , a tray  6 , a vibration mechanism  8 , and a vibration adjustment mechanism  9 . 
         [0071]    Belt cleaning blade  5  abuts against intermediate transfer belt  421  and scrapes off toner which remains on intermediate transfer belt  421 . 
         [0072]    Under belt cleaning blade  5 , tray  6  is provided and collects toner scraped by belt cleaning blade  5 . Tray  6  has one end side in a vicinity of intermediate transfer belt  421 . Tray  6  has one end side set to be higher in level than the other end side thereof. Tray  6  is thus inclined, and accordingly, toner (waste toner) which has been scraped and fallen on tray  6  moves toward the other end side and is thus collected. 
         [0073]    To allow the toner (waste toner) scraped and fallen on tray  6  to be smoothly moved toward the other end side, vibration mechanism  8  is used. 
         [0074]    Vibration mechanism  8  is timed, as prescribed, to impinge on the other end side of tray  6  to vibrate tray  6  to move the toner from one end side to the other end side. 
         [0075]    Vibration adjustment mechanism  9  changes a manner of vibration imparted by vibration mechanism  8  to tray  6 . 
         [0076]    &lt;C. Description of Cleaning State Accompanying Steering Control&gt; 
         [0077]      FIGS. 3A and 3B  are diagrams illustrating a cleaning state accompanying a steering control based on an embodiment. 
         [0078]      FIG. 3A  shows a normal state before performing the steering control. 
         [0079]    A case where intermediate transfer belt  421  is suspended by drive rollers  423 C and  423 D is shown as an example. 
         [0080]    Belt cleaning blade  5  abuts against intermediate transfer belt  421  at a prescribed angle. 
         [0081]    Drive roller  423 C is configured such that it has one end side having an axial position changed in a forward/backward direction by the steering control mechanism. The roller has the other end side having an axial position fixed. 
         [0082]    In this example, drive roller  423 C has one end side positionally set in an initial state, and drive roller  423 C has a longitudinal direction parallel to belt cleaning blade  5 . 
         [0083]    Accordingly, belt cleaning blade  5  and intermediate transfer belt  421  abut against each other in a uniform amount and toner is scraped off in a uniform amount regardless of location. 
         [0084]    With reference to  FIG. 3B , a case is shown in which drive roller  423 C has one end side having an axial position changed by the steering control mechanism. 
         [0085]    More specifically a case is shown in which drive roller  423 C pivots about its other longitudinal end side&#39;s axial position. 
         [0086]    By the steering control, intermediate transfer belt  421  has a difference between its circumferential length at one longitudinal end side of drive roller  423 C and that at the other longitudinal end side of drive roller  423 C. Specifically, the belt is larger in length at one longitudinal end side of drive roller  423 C than at the other longitudinal end side of drive roller  423 C. Due to the difference in circumferential length, intermediate transfer belt  421  suspended by the drive rollers moves toward the other end side of drive roller  423 C relative to the axial direction thereof. 
         [0087]    Note that when the belt is smaller in length at one longitudinal end side of drive roller  423 C than at the other longitudinal end side of drive roller  423 C, intermediate transfer belt  421  suspended by the drive rollers moves toward one end side of drive roller  423 C relative to the axial direction thereof. 
         [0088]    In this example, drive roller  423 C has one end side moving forward and rotating so that belt cleaning blade  5  abuts against the intermediate transfer belt in a varying amount. Specifically, the abutment is larger in amount (or pressure) at one end side of drive roller  423 C, and accordingly, a larger amount of toner is scraped in that region. 
         [0089]    Accordingly, in the intermediate transfer unit having a steering control function, when a drive roller is positionally moved by steering control, it is necessary to adjust the waste toner collection system according to the steering control. 
         [0090]    &lt;D. Configuration of Steering Control Mechanism and Belt Cleaning Device  426 &gt; 
         [0091]      FIG. 4  illustrates a configuration of a steering control mechanism and belt cleaning device  426  based on an embodiment. 
         [0092]    With reference to  FIG. 4 , as the steering control mechanism, steering control motor  13 , gear  14 , and cam  15  are provided. 
         [0093]    A spring  17  is provided between the axis of drive roller  423 C at one end side and the casing of image formation apparatus  1  (not shown). 
         [0094]    Steering control motor  13  drives gear  14 . Gear  14  is coupled with cam  15 , and cam  15  rotates as gear  14  is driven. Cam  15  has a projection. Cam  15  abuts against the axis of drive roller  423 C at one longitudinal end side. The projection of cam  15  can press the axis of drive roller  423 C at one longitudinal end side to allow drive roller  423 C to have one end side with an axial position varied and thus adjusted in the forward/backward direction. Note that an intermediate position of an amount of displacement varied by the projection of cam  15  can be set as an initial position to allow drive roller  423 C to be adjusted in the forward/backward direction. 
         [0095]    When drive roller  423 C has one end side with the axial position moved forward, intermediate transfer belt  421  moves toward the other end side of drive roller  423 C relative to the axial direction thereof. In contrast, when drive roller  423 C has one end side with the axial position moved backward, intermediate transfer belt  421  moves toward one end side of drive roller  423 C relative to the axial direction thereof. 
         [0096]    Belt cleaning device  426  further includes a gear group  16 , a cam  22  having a projection coupled with gear group  16 , an impinging blade  141 , a pressing member  151 , a pressing member drive motor  162 , a fulcrum position setting roller  31 , and a central axis  30  of fulcrum position setting roller  31 . 
         [0097]    Pressing member drive motor  162 , pressing member  151 , and impinging blade  141  configure vibration mechanism  8  which vibrates tray  6 . 
         [0098]    Furthermore, cam  22 , fulcrum position setting roller  31 , and central axis  30  configure vibration adjustment mechanism  9  which changes a manner of vibration of the vibration mechanism. 
         [0099]    An operation of vibration mechanism  8  which vibrates tray  6  will now be described. When pressing member drive motor  162  is driven, pressing member  151  which has the projection rotates and presses impinging blade  141  by the projection. 
         [0100]    Impinging blade  141  is designed to have one end side with a tip bent and, with this bent, impinging blade  141  impinges on tray  6 . As impinging blade  141  is pressed by the projection of pressing member  151 , impinging blade  141  rotates with the position of fulcrum position setting roller  31  serving as a fulcrum and thus has one end side moved to a position upper than tray  6 . 
         [0101]    And as pressing member  151  further rotates and the projection is passed, impinging blade  141  is no longer pressed by pressing member  151  and returns to an initial state. 
         [0102]    As impinging blade  141  is no longer pressed by pressing member  151 , impinging blade  141  impinges on tray  6  from the upper position. 
         [0103]    As impinging blade  141  impinges on tray  6 , tray  6  vibrates and waste toner moves toward the other end side (or lower side) of tray  6 . 
         [0104]    Hereinafter, an operation of vibration adjustment mechanism  9  which changes a manner of vibration of the vibration mechanism will be described. 
         [0105]    Gear group  16  is composed of a plurality of gears coupled between cam  22  and gear  14 . 
         [0106]    As steering control motor  13  is driven, gear  14  rotates, and its driving force is transmitted to cam  22  via gear group  16 . 
         [0107]    In this example, when steering control motor  13  is driven to move the axis of drive roller  423 C at one longitudinal end side forward, cam  22  presses central axis  30  by the projection. As cam  22  presses the axis by the projection, central axis  30  moves forward. This changes the position of fulcrum position setting roller  31  forward. 
         [0108]    When the position of fulcrum position setting roller  31  varies, the fulcrum position of impinging blade  141  varies. Accordingly, impinging blade  141  vibrates tray  6  in a different manner. 
         [0109]    Specifically, when the position of fulcrum position setting roller  31  moves forward, the position of one end side of impinging blade  141  moves further upward. This allows impinging blade  141  to impinge on tray  6  with larger force to vibrate tray  6  with a large amplitude. 
         [0110]    &lt;E. Configuration of Vibration Mechanism  8  and Vibration Adjustment Mechanism  9 &gt; 
         [0111]      FIG. 5  illustrates a configuration of vibration mechanism  8  and vibration adjustment mechanism  9  based on an embodiment. 
         [0112]    With reference to  FIG. 5 , as vibration mechanism  8  are shown impinging blades  141 - 143  provided at three locations, as one example, as an impinging blade which impinges on tray  6 , and pressing members  151 - 153  provided to correspond to impinging blades  141 - 143 , respectively. 
         [0113]    Impinging blade  141  is provided on one axial end side of drive roller  423 C. Impinging blade  143  is provided on the other axial end side of drive roller  423 C. Impinging blade  142  is provided between impinging blade  141  and impinging blade  143 . 
         [0114]    As vibration adjustment mechanism  9  are shown fulcrum position setting rollers  31 - 33  associated with impinging blades  141 - 143 , respectively, and setting the fulcrum positions of impinging blades  141 - 143 , central axis  30  shared by fulcrum position setting rollers  31 - 33 , and cam  22  which adjusts the position of central axis  30 . 
         [0115]    As has been described above, as pressing member drive motor  162  is driven, pressing members  151 - 153  having projections rotate and press impinging blades  141 - 143  by the projections. 
         [0116]    And as pressing members  151 - 153  further rotate and the projections are passed, impinging blades  141 - 143  are no longer pressed. And impinging blades  141 - 143  impinge on tray  6  from an upper position. 
         [0117]    As impinging blade  141  impinges on tray  6 , tray  6  vibrates and waste toner moves toward the other end side (or lower side) of tray  6 . 
         [0118]    Furthermore, as has been described above, as cam  22  presses the axis by the projection, central axis  30  moves forward. In this example, central axis  30  on the side of fulcrum position setting roller  31  is provided movably. Furthermore, it is assumed that central axis  30  on the side of fulcrum position setting roller  33  is fixed. 
         [0119]    Accordingly, central axis  30  pivots with the fixed side serving as a pivot and fulcrum position setting roller  31  positionally moves forward. Note that as central axis  30  pivots, fulcrum position setting rollers  31  and  32  also move forward, however, fulcrum position setting roller  31  displaces in the largest amount. 
         [0120]    Accordingly, when central axis  30  is moved forward by the projection of cam  22 , impinging blade  141  impinges with larger force than impinging blade  143 . More specifically, impinging blade  141  provided on one axial end side of drive roller  423 C impinges with larger force than the other impinging blades. 
         [0121]    As has been described with reference to  FIG. 3B , when drive roller  423 C has one end side moved forward and thus rotated, belt cleaning blade  5  abuts against the intermediate transfer belt in a varying amount. Specifically, the abutment is larger in amount (or pressure) at one end side of drive roller  423 C, and accordingly, a larger amount of toner is scraped in that region. More specifically, in tray  6 , an amount of toner at a region thereof corresponding to one end side of drive roller  423 C increases. 
         [0122]    Accordingly, impinging on the region of tray  6  corresponding to one end side of drive roller  423 C by impinging blade  141  with a larger force than the other regions can increase vibration in amplitude to collect toner in an increased amount. 
         [0123]    Note that while in the present example a system has been described in which the region of tray  6  corresponding to one end side of drive roller  423 C in which toner builds up in a large amount is vibrated with a larger amplitude than the other regions thereof, it is also possible to render central axis  30  on the side of fulcrum position setting roller  33  movable. In that case, central axis  30  moves forward in parallel with the axis of drive roller  423 C, and impinging blades  141 - 143  all impinge with uniformly increased forces. This can increase the amount of toner collected throughout tray  6 . 
         [0124]    Furthermore, while there is a possibility that when impinging blades  141 - 143  impinge on tray  6  with an increased force, the impinging sound, which will be noise, may also increase, impinging on the region of tray  6  corresponding to one end side of drive roller  423 C by impinging blade  141  with a larger force than impinging the other regions of tray  6  allows increased waste toner to be appropriately collected and allows an impinging sound to be reduced to minimize noise. 
         [0125]    &lt;F. Control Flow&gt; 
         [0126]      FIG. 6  illustrates a flow of printing control of image formation apparatus  1  based on an embodiment. 
         [0127]    As shown in  FIG. 6 , driving the intermediate transfer belt is started (step S 2 ). Control portion  100  drives drive roller  423  to drive intermediate transfer belt  421 . 
         [0128]    Subsequently, printing is started (step S 4 ). Control portion  100  controls image processing portion  300  and image forming portion  400  to perform a process for printing on sheet S. 
         [0129]    Subsequently, whether there is any detection by the belt position detection sensor is determined (step S 6 ). Steering control portion  155  determines whether a detection input of belt position detection sensor  251  is received. 
         [0130]    Subsequently, in step S 6 , when there is detection by the belt position detection sensor (YES in step S 6 ), an amount of steering is calculated (step S 8 ). Steering control portion  155  calculates an amount of steering based on the detection input of belt position detection sensor  251 . 
         [0131]    Subsequently, the steering control motor is rotated (step S 10 ). Steering control portion  155  operates, based on the result of the calculation of the amount of steering, to rotate and thus control steering control motor  13  to resolve a positional offset of intermediate transfer belt  421 . 
         [0132]    Subsequently, the fulcrum position setting roller is adjusted (step S 12 ). As steering control motor  13  is rotated, gear  14  is driven, and cam  22  rotates via gear group  16 . Accordingly, central axis  30  moves and fulcrum position setting roller  31  is positionally adjusted. 
         [0133]    In contrast, in step S 6 , when there is no detection by the belt position detection sensor (NO in step S 6 ), steps S 8 -S 12  are skipped, and the control proceeds to step S 14 . 
         [0134]    Subsequently, whether a set number of sheets have been printed is determined (step S 14 ). 
         [0135]    In step S 14 , when it is determined that the set number of sheets have been printed (YES in step S 14 ), the process ends (END). Control portion  100  determines whether the set number of sheets have been printed, and if so, control portion  100  ends the process. 
         [0136]    In contrast, in step S 14 , when it is determined that the set number of sheets have not been printed (NO in step S 14 ), then whether a predetermined number of sheets have been printed is determined (step S 16 ). Control portion  100  determines whether the predetermined number of sheets have been printed. The predetermined number of sheets is set previously, for the sake of illustration. Note that this value can be changed as desired. 
         [0137]    In step S 16 , when it is determined that the predetermined number of sheets have been printed (YES in step S 16 ), the pressing member drive motor is driven (step 
         [0138]    S 18 ). When control portion  100  determines that the predetermined number of sheets have been printed (YES in step S 16 ), control portion  100  drives pressing member drive motor  162  to cause the projections of pressing members  151 - 153  to press impinging blades  141 - 143 . 
         [0139]    Subsequently, impingement is done (step S 20 ). 
         [0140]    Control portion  100  drives pressing member drive motor  162  to rotate pressing members  151 - 153  until the projections are passed. And after the projections are passed, pressing impinging blades  141 - 143  is resolved. Thus impinging blades  141 - 143  impinge on tray  6  from an upper position. 
         [0141]    And the control returns to step S 4  to repeat the above process. 
         [0142]    In step S 16 , when it is determined that the predetermined number of sheets have not been printed (NO in step S 16 ), the control returns to step S 4  to repeat the above process. 
         [0143]    By the above process, when steering control motor  13  rotates to perform steering control, a fulcrum position setting roller is also adjusted. In that condition, by impinging on tray  6  by an impinging blade, vibration can be imparted in a manner changed to a state different than normal. More specifically, as has been set forth above, when the region of tray  6  corresponding to one end side of drive roller  423 C receives an increased amount of toner, tray  6  can be vibrated with an increased amplitude to collect an increased amount of toner. 
         [0144]    This can prevent waste toner remaining on tray  6  from building up and returning to intermediate transfer belt  421 . This can in turn prevent an image from being smeared and allows a stable output image to be obtained. 
         [0145]    In the above system, whether a predetermined number of sheets have been printed is determined, and when it is determined that the predetermined number of sheets have been printed, pressing member drive motor  162  is driven to cause the projections of pressing members  151 - 153  to press impinging blades  141 - 143  to provide impingement, however, this is not exclusive, and for example a distance travelled by intermediate transfer belt  421  may be measured and whether impingement should be provided may be determined based on the distance travelled as measured. 
         [0146]    Specifically, whether a distance travelled by intermediate transfer belt  421  is equal to or greater than a prescribed distance may be determined and if so, pressing member drive motor  162  may be driven to provide impingement. 
         [0147]    When the pressing member drive motor is driven based on the number of sheets printed, a possibility that the amount of toner may vary depending on the size of sheet S cannot be handled, whereas when the pressing member drive motor is driven based on a distance travelled by intermediate transfer belt  421 , the pressing member drive motor is driven based on the travelled distance, irrespective of the size of sheet S, and a stable amount of toner can be collected. 
         [0148]    &lt;First Exemplary Variation&gt; 
         [0149]    While in the above system a configuration has been described in which a fulcrum position setting roller is positionally adjusted to allow tray  6  to be vibrated with an adjusted amplitude, the vibration may not be adjusted in amplitude and instead be adjusted in frequency (or in how many times the vibration is provided). Specifically, in order to increase the amount of toner collected, how many times tray  6  is impinged on by an impinging blade may be adjusted. For example, how many times tray  6  is impinged on by impinging blades by rotating pressing members  151 - 153  by pressing member drive motor  162  may be set to be twice as many. The number of times can be set as desired. Furthermore, it is also possible to adjust vibration frequency in combination with vibration amplitude. 
         [0150]    &lt;Second Exemplary Variation&gt; 
         [0151]    Furthermore, it is also possible to change a manner of vibration of the vibration mechanism based on a writing condition under which printing on sheet S is done. 
         [0152]    Specifically, the manner of vibration of the vibration mechanism may be changed based on an image writing region&#39;s size, an image writing density, etc. 
         [0153]    For example, for a small image writing region, no image is written in a vicinity of a region of an end of intermediate transfer belt  421  at one end side of drive roller  423 C, and accordingly, it is believed that belt cleaning blade  5  would scrape a small amount of waste toner. 
         [0154]    Accordingly, for an image writing region equal to or greater than a predetermined area, the manner of vibration by vibration mechanism  8  may be changed, whereas for an image writing region smaller than the predetermined area, the manner of vibration by vibration mechanism  8  may not be changed. 
         [0155]    As one example, while in the  FIG. 6  system a system has been described in which in step S 12  a fulcrum position setting roller is adjusted according to steering control, an image writing region may be determined and if it is equal to or greater than the predetermined area, the manner of vibration by vibration mechanism  8  (or the adjustment of the fulcrum position setting roller) may be performed, whereas if the image writing region is smaller than the predetermined area, the manner of vibration by vibration mechanism  8  (or the adjustment of the fulcrum position setting roller) may not be performed. 
         [0156]    Furthermore, for example, it is believed that for high image writing density, a large amount of toner remains on intermediate transfer belt  421 , whereas for low image writing density, a small amount of toner remains on intermediate transfer belt  421 . Accordingly, the manner of vibration of the vibration mechanism may also be changed based on image writing density. 
         [0157]    Specifically, for an image writing density equal to or greater than a predetermined density, the manner of vibration by vibration mechanism  8  may be changed, whereas for an image writing density less than the predetermined density, the manner of vibration by vibration mechanism  8  may not be changed. Note that the above may be performed in combination. 
         [0158]    As one example, while in the  FIG. 6  system a system has been described in which in step S 12  a fulcrum position setting roller is adjusted according to steering control, an image writing density may be determined and if it is equal to or greater than a predetermined density, the manner of vibration by vibration mechanism  8  (or the adjustment of the fulcrum position setting roller) may be performed, whereas if the image writing density is smaller than the predetermined density, the manner of vibration by vibration mechanism  8  (or the adjustment of the fulcrum position setting roller) may not be performed. 
         [0159]    While the present invention has been described in embodiments, it should be understood that the embodiments disclosed herein are illustrative and non-restrictive in any respect. The scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the meaning and scope equivalent to the terms of the claims.