Abstract:
An image holding element cleaning apparatus includes: an image holding element; an image holding element cleaning unit that touches and detaches from the image holding element and that cleans the image holding element when the image holding element cleaning unit touches the image holding element; a detection unit that detects at least one of a position of the image holding element cleaning unit on the image holding element when the image holding element cleaning unit touches the image holding element, and a position of the image holding element cleaning unit on the image holding element when the image holding element cleaning unit detaches from the image holding element; and an adjusting unit that adjusts at least one of an operation timing of touching and an operation timing of detaching based on a result of a detection by the detection unit, the operation timing of touching being the timing when the image holding element cleaning unit touches the image holding element, and the operation timing of detaching being the timing when the image holding element cleaning unit detaches from the image holding element.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2006-236502 filed Aug. 31, 2006. 
       BACKGROUND 
     1. Technical Field 
       [0002]    The present invention relates to an image holding element cleaning apparatus and an image forming apparatus. 
       SUMMARY 
       [0003]    According to an aspect of the invention, there is provided an image holding element cleaning apparatus including: an image holding element; an image holding element cleaning unit that touches and detaches from the image holding element and that cleans the image holding element when the image holding element cleaning unit touches the image holding element; a detection unit that detects at least one of a position of the image holding element cleaning unit on the image holding element when the image holding element cleaning unit touches the image holding element, and a position of the image holding element cleaning unit on the image holding element when the image holding element cleaning unit detaches from the image holding element; and an adjusting unit that adjusts at least one of an operation timing of touching and an operation timing of detaching based on a result of a detection by the detection unit, the operation timing of touching being the timing when the image holding element cleaning unit touches the image holding element, and the operation timing of detaching being the timing when the image holding element cleaning unit detaches from the image holding element. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0004]    Embodiments of the present invention will be described in detail based on the following figures, wherein: 
           [0005]      FIG. 1  illustrates a conceptual diagram which shows schematically an exemplary example of an image forming apparatus to which the invention is applied; 
           [0006]      FIG. 2  illustrates a block diagram which schematically shows a control system; 
           [0007]      FIG. 3  illustrates an enlarged view which schematically shows the periphery of a cleaning apparatus shown in  FIG. 1 ; 
           [0008]      FIG. 4  illustrates a diagram which shows a state in which a retraction line is produced; 
           [0009]      FIG. 5  illustrates a diagram which shows a state in which a contact line is produced; 
           [0010]      FIGS. 6A to 6E  illustrate conceptual diagrams which show a position adjustment mode; 
           [0011]      FIG. 7  illustrates a flowchart which shows an exemplary example of a processing procedure of the position adjustment mode; and 
           [0012]      FIGS. 8A and 8B  illustrate diagrams which show an exemplary example of an operation that is to be performed after contact and retraction positions of a blade have been adjusted; and 
           [0013]      FIGS. 9A to 9C  illustrate diagrams which explain the standard value of the invention. 
       
    
    
     DETAILED DESCRIPTION 
     (1) First Embodiment 
     (Configuration) 
       [0014]      FIG. 1  is a conceptual diagram which shows schematically an example of an image forming apparatus which makes use of the invention. A color printer  100  is shown in  FIG. 1  as an example of an image forming apparatus. The color printer  100  includes a single-drum type developing machine  101 . The developing machine  101  includes four developing units  102  which correspond to primary colors of YMCK (Yellow, Magenta, Cyan, Black), respectively. Each developing unit  102  includes a toner bottle  102   a  and a toner supply mechanism  102   b . Each toner bottle  102   a  holds any of YMCK toners which corresponds to the developing unit  102  which holds the relevant toner bottle  102   a.    
         [0015]    A light-sensitive material drum  103  is disposed in such a manner as to be in contact with the developing machine  101 . The light-sensitive material drum  103  is partially exposed by a scanning light that is shone from an optical writing apparatus  104 , whereby a latent image is formed on a surface thereof. The optical writing apparatus  104  (ROS) is an exposing scanner for writing and includes a laser emitting unit  104   a  and an optical system  104   b  which guides a laser beam. A latent image is formed on the surface of the light-sensitive material drum  103  by scanning light shone on to the light-sensitive material drum  103  from the optical writing apparatus  104  in association with the rotation of the light-sensitive material drum  103 . The surface of the light-sensitive material drum  103  is charged in accordance with the latent image, and any of the YMCK toners is selectively supplied to the light-sensitive material drum  103  from one of the developing units  102  of the developing machine  101  by being attracted by an electric field generated in association with the charging. Thus, any of the YMCK toners is caused to adhere to the surface of the light-sensitive material drum  103  in accordance with the latent image which is formed by the optical writing apparatus  104  in the way described above, so as to form a toner image in accordance with the latent image. 
         [0016]    A light-sensitive material drum cleaning apparatus  105  is provided in proximity to the light-sensitive material drum  103 . The light-sensitive material drum cleaning apparatus  105  includes a function to move a light-sensitive material drum blade  105   a  into contact with the surface of the light-sensitive material drum  103  so as to scrape thereoff residual toner which remains on the surface of the light-sensitive material drum  103  by making use of the rotational force of the light-sensitive material drum  103 . In addition, toner so scraped off is recovered by a toner recovery unit, not shown. 
         [0017]    A transfer belt  106  is disposed in such a state that the belt is in contact with the light-sensitive material drum  103 . In addition, a primary transfer roller  108  is disposed in a position which oppositely faces the light-sensitive material drum  103  across the transfer belt  106  in such a manner as to hold the transfer belt  106  between the light-sensitive material drum  103  and itself. A bias voltage, which is necessary when transferring a toner image, is made to be applied between the light-sensitive material drum  103  and the primary transfer roller  108 . The transfer belt  106  is transferred by a drive roller  109  at a speed which is in synchronism with the rotation of the light-sensitive material drum  103 . As this occurs, the transfer belt  106  comes to be held between the light-sensitive material drum  103  and the primary transfer roller  108 , and a bias voltage is then applied between the light-sensitive material drum  103  and the primary transfer roller  108 , whereby a primary transfer of a toner image is carried out from the light-sensitive material drum  103  to the transfer belt  106 . As this occurs, in the case of a color image, a primary transfer is carried out four times so as to cover the four colors of YMCK, and images of four colors are superposed one on another, whereby a color toner image is formed on the transfer belt  106 . On the other hand, in the case of a monochrome image, a transfer is carried out for one of the four colors of YMCK. 
         [0018]    A toner sensor  111  is disposed in proximity to the transfer belt  106 . The toner sensor  111  is an optical sensor and monitors optically the condition of toner that adheres to the transfer belt  106 . Whether or not a toner image of a specified density is formed is determined from an output from the toner sensor  111 . A mark detection sensor  121  is disposed in proximity to the transfer belt  106 . A position detection mark  121   a  that is formed on the transfer belt  106  is detected by the mark detection sensor  121 . This position detection mark  121   a  is made use of to determine a position where a primary transfer is carried out on to the transfer belt  106 . In addition, the position detection mark  121   a  is also made use of as a mark for adjustment of the position of the blade  110   a.    
         [0019]    A sheet cassette which holds printing sheets  122  as recording materials is installed in a bottom portion of the color printer  100 . Printing sheets  122  are transferred along a sheet transfer path  125  by a sheet transfer system which is represented by reference numeral  124 . Secondary transfer rollers  126   a  and  126   b , which are transfer members, are disposed in an intermediate position along the length of the sheet transfer path  125 . A printing sheet, not shown, which has been transferred along the sheet transfer path  125  as far as the secondary transfer rollers  126   a  and  126   b  and the transfer belt are held between the secondary transfer rollers  126   a  and  126   b , whereby the toner image now transferred on the surface of the transfer belt  106  is further secondarily transferred on to the printing sheet. 
         [0020]    In secondarily transferring the toner image on to the printing sheet, the secondary transfer roller  126   a  is brought into contact with the transfer belt  106  when the toner image approaches the secondary transfer roller  126   a . Here, “being brought into contact” means that a state is brought about in which the secondary transfer roller  126   a  is brought into contact with the transfer belt  106  so as to be in a position to assist in secondary transfer. Then, after the toner image has been secondarily transferred on to the printing sheet, the secondary transfer roller  126   a  is retracted from the transfer belt  106 . Here, “being retracted” means that a state is brought about in which the secondary transfer roller  126   a  is moved apart or separated from the transfer belt  106 . The reason the secondary transfer roller  126   a  is brought into contact with and retracted from the transfer belt  106  is to avoid a risk that toner on contact and retraction lines which are formed on the transfer belt  106  stick to the secondary transfer roller  126   a  to produce lines of toner dirt on a back of a printing sheet when a secondary transfer is carried out on the printing sheet. Note that the contact and retraction lines will be described later on. 
         [0021]    The printing sheet on which the toner image is travels along the sheet transfer path  125  and is transferred between fixing rollers  127   a  and  127   b . The fixing roller  127   b  incorporates therein a heater for heating a toner material making up the toner image on the printing sheet when the printing sheet is transferred in the manner described above. The toner is fixed by being so heated, and an image is formed on the printing sheet. The printing sheet, on which the fixing process has been so completed, is then discharged from a discharge mechanism  128  on to a discharge surface  129 . Note that reference numeral  130  denotes a sheet transfer path for double-side printing. 
         [0022]    A cleaning apparatus  110  is disposed in proximity to the transfer belt  106 . A blade  110   a , which is an image holding element cleaning unit, and a toner recovery unit  110   b  are disposed on the cleaning apparatus  110 , whereby toner, which still remains on the transfer belt  106  without being secondarily transferred to the printing sheet, is scraped off by the blade  110   a  which is in contact with the transfer belt  106  and is then recovered into the toner recovery unit  110   b . In addition, the details of the cleaning apparatus  110  will be described later on. 
         [0023]    In scraping off toner which remains on the transfer belt  106 , the blade  110   a  is brought into contact with the transfer belt  106  when the position on the transfer belt  106  where the toner image formed thereon was primarily transferred approaches the blade  110   a . Here, “being brought into contact” means that a state is brought about in which the blade  110   a  is brought into contact with the transfer belt  106  so as to get ready for cleaning the transfer belt  106 . 
         [0024]    Then, when the position on the transfer belt  106  where the toner image formed thereon was primarily transferred has passed the blade  110   a , the blade  110   a  is retracted from the transfer belt  106 . Here, “being retracted” means that a state is brought about in which the blade  110   a  is moved apart or separated from the transfer belt  106 . The reason the blade  110   a  is brought into contact with and retracted from the transfer belt  106  is to prevent toner images from being scraped off until images of four colors have been superposed one on another in the case of color printing in which a primary transfer is carried out four times to cover the four colors of YMCK so to primarily transfer images in four colors of YMCK on to the transfer belt  106  in a superposed fashion. Although the blade  110   a  produces contact and retraction lines when the blade  110   a  moves into contact with and apart from the transfer belt  106 , the detailed background of production of the contact and retraction lines will be described later on. 
         [0025]    In  FIG. 1 , reference numeral  131  denotes a control unit that controls the operation of the color printer  100 .  FIG. 2  is a block diagram which shows schematically a control system which includes the control unit  131 . The control unit  131  includes a CPU (central processing unit)  201 , a ROM (read only memory)  202  and a RAM (random access memory)  203 . The CPU  201  governs the operation of the whole control system shown in  FIG. 2  and has a function to execute an operation procedure which will be described later on. The ROM  202  stores therein an operation program for executing the operation procedure which will be described later on and data which is necessary for the operation of the program. Values are contained in the data which will be utilized in the operation procedure which will be described later on. 
         [0026]    In execution of the operation procedure which will be described later on, the RAM  203  functions as a working area which stores temporarily program data and various types of data and as a storage unit that stores various data that will be obtained in the operation procedure which will be described later on. A nonvolatile memory is also contained in the RAM  203 , and necessary data is held even though a power supply is switched off. For example, data on contact and retracted positions of the blade  110   a  before the contact and retracted positions of the blade  110   a  are adjusted are stored in the RAM  203 . A drive control circuit  205  is a circuit for controlling the developing machine  102 , the light-sensitive material drum  103 , the transfer belt  106 , the cleaning apparatus  110 , the fixing rollers  127   a  and  127   b  and a motor for driving the printing sheet transfer system  124 . 
         [0027]    A sensor  204  detects a rotational condition and a rotational angle of the motor which is driven by the drive control circuit  205 , a transfer condition of printing sheets, an image forming number and an image forming quantity. The mark detection sensor  121  and the toner sensor  111  are also included in the sensor  204 . 
         [0028]    Thus, the example of the single-drum type image forming apparatus has been described which utilizes the developing unit into which the four colors of YMCK are incorporated and the single light-sensitive material drum. However, the invention can also be applied to an image forming apparatus which includes tow or more sets of developing units and light-sensitive material drums. 
       (Operation Example) 
       [0029]    Firstly, an example of contact and retraction (separation) operations of the blade  110   a  will be described.  FIG. 3  is an enlarged view schematically showing the periphery of the cleaning apparatus  110  shown in  FIG. 1 . The cleaning apparatus  110  is given power at a predetermined timing from a drive unit, not shown, by the drive control circuit  205  so as to perform contact and retraction operations of the blade  110   a . To describe the retraction operation of the operations performed by the cleaning apparatus  110 , the drive unit, not shown, transmits power to a cam shaft  110   c , and a cam  110   d  rotates by virtue of rotation of the cam shaft  110   c , whereby the power so transmitted is applied to a link arm  110   f  in a direction indicated by an arrow a by virtue of rotation of the cam  110   d . Then, the link arm  110   f , which is in contact with the cam  110   d  by virtue of an action of an arm spring  110   e , rotates about a link arm rotational center shaft  110   g  by virtue of a rotational action of the cam  110   d  to transmit the power in a direction indicated by an arrow b, so that the power is then transmitted to a link arm facing member  110   h . Here, while a component which produces a rotational driving force is illustrated as the drive unit, a component such as a solenoid which produces a linear driving force may be utilized as the drive unit. 
         [0030]    The link arm facing member  110   h , to which the power is so transmitted, is connected to a bracket rotational center shaft  110   i , and furthermore, a bracket  110   j  is also connected to the bracket rotational center shaft  110   i , whereby the power is then transmitted to the bracket  110   j . Then, the bracket  110   j  retracts the blade  110   a  and a film seal  110   l  from the transfer belt  106  towards a direction indicated by an arrow c by virtue of the power which is so transmitted to the bracket  110   j.    
         [0031]    On the other hand, to describe the contact operation of the blade  110   a , when power is transmitted further from the drive unit, not shown, to the cam shaft  110   c , the blade  110   a  and the film seal  110   l  are brought into contact with the transfer belt by an action of a bracket spring  110   k . The blade  110   a , which is brought into contact with the transfer belt  106 , scrapes off toner remaining on the transfer belt  106 , and the toner so scraped off is then recovered by the toner recovery unit  110   b . The film seal  110   l , which is brought into contact with the transfer belt  106 , prevents the toner scraped off by the blade  110   a  from scattering. 
         [0032]      FIG. 4  is a diagram which shows a state a retraction line, which is produced when the blade  110   a  is retracted from the transfer belt  106  as shown in  FIG. 3 , is produced.  FIG. 5  is a diagram which shows a state a contact line, which is produced when the blade  110   a  is brought into contact with the transfer belt  106  as shown in  FIG. 3 . Note that the transfer belt  106  is driven in a direction indicated by an arrow by the drive roller  109 . Firstly, to describe the production of a retraction line, when the blade  110   a , which is in contact with the transfer belt  106 , scrapes off toner remaining on the transfer belt  106 , part of the toner adheres to a distal end of the blade  110   a . Then, in the event that the blade  110   a  is retracted with the toner so adhering thereto, dirt in the form of a line  110   m  is caused to adhere on to the transfer belt as soon as the blade  110   a  moves apart from the transfer belt  106 . 
         [0033]    Next, to describe the production of a contact line, when the distal end of the blade  110   a  is brought into contact with the transfer belt  106 , the toner which adheres to the distal end of the blade  110   a  returns on to the transfer belt  106  as soon as the blade  110   a  is brought into contact with the transfer belt  106 , whereby dirt in the form of a line  110   n  is caused to adhere on to the transfer belt  106 . 
         [0034]    Next, an example of a method will be described in which the contact and retraction positions of the blade  110   a  are detected for adjustment.  FIGS. 6A to 6E  show conceptual diagrams of a position adjustment mode which illustrate an example of a method for adjusting the contact and retraction positions of the blade  110   a . Here, the “position adjustment mode” is a mode in which the contact and retraction positions of the blade  110   a  are shifted by a specified value so as to adjust the contact and retraction positions of the blade  110   a . In addition, note that shifting the contact and retraction positions of the blade  110   a  by the specified value is to measure a deviation between the contact and retraction positions. 
         [0035]      FIG. 6A  shows a case where the transfer belt  106  is transferred in a direction indicated by an arrow by the drive roller  109  with halftones  601  and  602  of an image formed on the transfer belt  106  and the blade  110   a  is adjusted to an ideal contact position  603  and retraction position  603  in a non-image area G. The ideal contact position  603  and retraction position  603  lie in a position which is apart from a home position by a standard value L. 
         [0036]    The standard value is an aimed position where fluctuations in design are considered ( FIG. 9A ). The aimed position is a position where even the maximum fluctuation during the contact and the maximum fluctuation during the retraction do not interfere with the contact/retraction positions of 2nd BTR. At this time, the maximum fluctuations during the contact and the retraction may not be equal. 
         [0037]    As shown in  FIG. 9B , if the standard position is early, the fluctuation of the standard position during the contact interferes with 2nd BTR retraction position, thereby a contact line is transferred to 2nd BTR, then the line becomes dirt on a back side at the next print. 
         [0038]    As shown in  FIG. 9C , if the standard position is late, the fluctuation of the standard position during the retraction interferes with 2nd BTR contact position, thereby a retraction line is transferred to 2nd BTR, then the line becomes dirt on a back side at the next print. 
         [0039]      FIG. 6B  is a diagram showing a contact position  605  which is shifted from the ideal contact position  603  by a specified value C 0 .  FIG. 6C  shows a case where a contact line  606  is formed which is produced when the blade  110   a  is brought into contact with the transfer belt  106  at the contact position  605  which is shifted by the specified value C 0 . As this occurs, the position detection mark  121   a  on the transfer belt  106  is read by the mark detection sensor  121 , and an end portion of a toner image of the contact line  606  on the transfer belt  106  is read by the toner sensor  111 . Thereafter, a measured value C 1  is calculated from information read by the mark detection sensor  121  and the toner sensor  111 . In this case, since the calculated value C 1  indicates that the contact position remains at the ideal position of the blade  110   a , no adjustment in position is carried out. 
         [0040]    On the other hand,  FIG. 6D  shows a case where the contact position of the blade  110   a  lies in a contact position  607  which deviates from the ideal contact position  603 . Then, the blade  110   a  is brought into contact with the transfer sheet  106  at a contact position  608  which is caused to deviate by the specified value C 0  from the deviating contact position  607 .  FIG. 6E  shows a case where a contact ling  609  is formed which is produced when the blade  110   a  is brought into contact with the transfer belt  106  at the contact position  608  which is caused to deviate by the specified value C 0  from the deviating contact position  607 . As this occurs, the position detection mark  121   a  on the transfer belt  106  is read by the mark detection sensor  121 , and an end portion of a toner image of the contact line  609  on the transfer belt  106  is read by the toner sensor  111 . Thereafter, a measured value C 1  is calculated from information read by the mark detection sensor  121  and the toner sensor  111 . Then a correction value C X  is obtained. 
         [0041]    The correction value C X  is obtained by C X =L−C 1 −C 0 . An adjustment value A is obtained using the correction value C X  obtained from the operation. The adjustment value A is obtained by A=C 0 +C X . Then, by adjusting the contact position by a quantity equivalent to the adjustment value A which is obtained from the operation above, the contact position of the blade  110   a  can be adjusted to the ideal contact position. Note that in the case of the ideal contact position  603  in  FIG. 6B , since the correction value C X =L−C 1 −C 0 =0, no adjustment is carried out. Next, in an adjustment method for the retraction position, while when adjusting the contact position, the contact position is shifted towards the halftone  601  by the quantity equivalent to the specified value C 0 , the retraction position is shifted towards the halftone  602  by the quantity equivalent to the specified value C 0 , and an end portion of a toner image of a retraction line is read by the toner sensor  111 , so as to obtain a correction value C X  for adjustment of the retraction position. 
         [0042]    Note that while in the position adjustment methods, the end portions of the toner images of the contact line and the retraction line of the blade  110   a  are read by the toner sensor  111  so as to obtain the correction value C X  for adjustment of the positions, a configuration may be adopted in which the blade  110   a  is set to be brought into contact with the transfer belt  106  on the halftone  601  and be retracted therefrom on the halftone  602  by increasing the specified value C 0  so as to clean the half tones  601  and  602 , and end portions of toner images of the half tones  601  and  602  which are partially cleaned are read by the toner sensor  111  so as to obtain a correction value C X . In addition, as to a timing when the position adjustment by the position adjustment mode is executed, the position adjustment may be executed every time a power supply for the color printer  100  is switched on or every time hundreds of prints are printed, or be executed by changing the setting in function of the color printer  100 . In addition, the end portions of the toner images may be made to be read not by the toner sensor  111  but by the mark detection sensor  121 . 
         [0043]      FIG. 7  is a flowchart showing an example of a processing procedure of the position adjustment mode of the image forming apparatus which is equipped with the configuration shown in  FIG. 1 . An operation program for executing the processing procedure shown in the flowchart in  FIG. 7  is stored in the ROM  202  shown in  FIG. 2 . 
         [0044]    In this embodiment, when the position adjustment mode is started (step S 701 ), data on the contact position is obtained (step S 702 ). After step S 702 , a process is executed for determining whether or not the absolute value of the correction value C x  is equal to or more than a predetermined value (step S 703 ). A value obtained in advance based on a predetermined contact position and a necessary data quantity that is necessary to realize the contact position and stored in the ROM  202  is used for a value based on which the determination is made. 
         [0045]    In this determination, a correction value C X  is calculated by an operation of corrected value C X =standard value L−measured value C 1 −specified value C 0 , and the value stored in the ROM  202  is compared with the absolute value of the correction value C X  to determine whether or not the absolute value of the correction value C X  is equal to or more than the predetermined value. As an example, if the absolute value of the correction value C X  before adjustment is equal to or more than 5 mm, the determination in step S 703  becomes YES. On the other hand, if the absolute value of the correction value C X  before adjustment is less than 5 mm, the determination in step S 703  becomes NO. 
         [0046]    If the absolute value of the correction value C X  of the contact position is equal to or more than the predetermined value, the determination in step S 703  becomes YES, and the flow proceeds to step S 704 . In step S 704 , a process for setting the contact position to the adjustment value A is performed. In the process for setting the contact position to the adjustment value A, an adjustment value A is calculated by operation of adjustment value A=specified value C 0 +correction value C X , and the contact position is set to the adjustment value so calculated. Thereafter, the flow proceeds to step S 705 . On the other hand, if the absolute value of the correction value C X  of the contact position is less than the predetermined value, the determination in step S 703  becomes NO, and the flow proceeds to step S 705  without performing the adjustment of the contact position. 
         [0047]    Next, in step S 705 , data on the retraction position is obtained, and after step S 705 , a process is performed for determining whether or not the absolute value of the correction value C x  of the retraction position is equal to or more than the predetermined value (step S 706 ). Then, if the determination in step S 706  is YES, setting the value of the retraction position to the adjustment value A is performed (step S 707 ), whereby the position adjustment mode ends (step S 708 ). On the other hand, if the determination in step S 706  is NO, the position adjustment mode ends without performing the adjustment of the retraction position (step S 708 ). 
         [0048]      FIGS. 8A and 8B  show diagrams which illustrate an example of an operation to be performed after the contact and retraction positions of the blade  110   a  have been adjusted.  FIGS. 8A and 8B  show a case where two toner images can be transferred on to the transfer belt  106  and shows contact and retraction positions of the blade  110   a  and the secondary transfer roller  126   a  in a non-image area H and a non-image area I on an Nth turn and an N+1th turn of the transfer belt  106 . 
         [0049]    In this embodiment, timings when the secondary transfer roller  126   a  moves into contact with and apart from the transfer belt  106  are set based on the adjustment of the contact and retraction positions of the blade  110   a  in such a manner that a contact (at a position X 2 ) of the secondary transfer roller  126   a , a retraction (at a position X 3 ) of the secondary transfer roller  126   a , a contact (at a position X 1 ) of the blade  110   a , a retraction (at a position X 4 ) of the blade  110   a , a contact (at a position X 6 ) of the secondary transfer roller  126   a  and a contact (at a position X 5 ) of the blade  110   a  occur in the order of passage of time in the non-image area H and the non-image area I on the transfer belt  106 . 
         [0050]    When a primary image  801  is secondarily transferred on to a printing sheet, the illustration thereof being omitted, on an Nth turn shown in  FIG. 8A , the secondary transfer roller  126   a  is brought into contact with the transfer belt  106  at the position X 2  in the non-image area H so as to transfer the primary image  801  on to a printing sheet, whereafter the secondary transfer roller  126   a  is retracted from the transfer belt  106  at the position X 3  on the non-image area I. Then, in order to scrape off toner of the primary image  801  which remains on the transfer belt  106  without having been secondarily transferred on to the printing sheet, the blade  110   a  is brought into contact with the transfer belt  106  at the position X 1  on the non-image area H so as to clean the transfer belt  106 , and after the transfer belt  106  has been so cleaned, the blade  110   a  is retracted from the transfer belt  106  at the position X 4  on the non-image are I. As this occurs, a contact line  803  is formed in the position X 1 , and a retraction ling  804  is formed in the position X 4 . Here, the reason the blade  110   a  is retracted from the transfer belt  106  in the non-image area I which lies right before a secondary image transfer position  802  is to avoid a risk that toner images to the third color which are formed in the secondary image transfer position  802  are scraped off. 
         [0051]    When a secondary image  805 , in which images of all the four colors have been completely transferred, is secondarily transferred on to a printing sheet on the N+1th turn of the transfer belt  106  shown in  FIG. 8A , the illustration thereof being omitted, the secondary transfer roller  126   a  is brought into contact with the transfer belt  106  at the position X 6  on the non-image area I, so that the secondary image  805  is transferred on to the printing sheet. Then, the blade  110   a  is brought into contact with the transfer belt  106  at the position X 5  in the non-image area I with a view to scraping off toner of the secondary image  805  which remains on the transfer belt  106  without having secondarily been transferred on to the printing sheet, so as to clean the surface of the transfer belt  106 . As this occurs, since the contact and retraction positions of the blade  110   a  are adjusted, the contact line  806  is formed in the position X 5 , and the retraction line  804  that is formed on the Nth turn and the contact line  806  that is formed on the N+1th turn of the transfer belt  106  come to be formed in substantially the identical positions on the transfer belt  106 . In addition, since the timings when the secondary transfer roller  126   a  moves into contact with and apart from the transfer belt  106  are set based on the adjustment of the contact and retraction positions of the blade  110   a , there occurs no risk that the secondary transfer roller  126   a  is soiled by toner of the contact line and the retraction line. 
         [0052]    Namely, since the contact and retraction positions of the blade  110   a  are adjusted properly, there can still be provided a construction in which the secondary transfer roller  126   a  is made difficult to be soiled even though the width of the non-image area is narrowed. In addition, even though there occurs a deviation in the contact and retraction positions of the blade  110   a  due to replacement of components of the cleaning apparatus, the relevant positions can be adjusted properly by the execution of the position adjustment mode. 
       (2) Second Embodiment 
       [0053]    While in the first embodiment, the position adjustment is performed by utilizing the mark detection sensor  121  for reading the position detection mark  121   a  and the toner sensor  111  for reading the condition of toner on the transfer belt  106  which are shown in  FIG. 1 , the position adjustment may be performed by utilizing an additional sensor, which is separate from the mark detection sensor  121  and the toner sensor  111 . 
       (3) Third Embodiment 
       [0054]    While in the first embodiment, the example of the image forming apparatus is described which makes use of the invention which is applied to the cleaning apparatus  110  shown in  FIG. 1 , there may be provided an image forming apparatus in which the contact position or retraction position of the blade is adjusted by utilizing an additional sensor while applying the invention to the light-sensitive material drum cleaning apparatus  105  which is in proximity to the light-sensitive material drum  103  shown in  FIG. 1 . 
         [0055]    In the description of the embodiments, while the program for executing the blade position adjustment mode and programs for executing the other operations which are described in the specification are stored in the ROM disposed within the apparatus, those programs can be provided while being stored in an appropriate storage medium such as another semi-conductor memory, an optical disk storage unit, a magnetic disk storage unit or a magneto-optical disk storage unit. 
         [0056]    The invention can be applied to an image forming apparatus such as a color printer, a Fax, a color photocopier and a composite machine thereof. 
         [0057]    The foregoing description of the exemplary embodiments of the present invention has been provided for the purpose of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments are chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various exemplary embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.