Patent Publication Number: US-9411299-B2

Title: Lubricant supply device, image forming apparatus, and pressing device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. application Ser. No. 11/508,238, filed Aug. 23, 2006, the entire content of which is incorporated herein by reference and claims priority under 35 U.S.C. 119 to Japanese Application No. 2005-276023, filed Sep. 22, 2005, Japanese Application No. 2005-336791, filed Nov. 22, 2005, Japanese Application No. 2006-021221, filed Jan. 30, 2006, Japanese Application No. 2006-093053, filed Mar. 30, 2006, and Japanese Application No. 2006-200270, filed Jul. 24, 2006. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a lubricant supply device supplying a lubricant scraped off a solid lubricant by contacting and rubbing the solid lubricant to a lubricant supplying target, an image forming apparatus such as a copier, a printer, a facsimile apparatus, etc., using the lubricant supply device, and a pressing device applicable to the lubricant supply device. 
     2. Discussion of the Background 
     As the lubricant supply device of this kind, for example, the one disclosed in Japanese Patent Laid-open Publication No. 2001-305907 is known. The lubricant supply device of the JP Publication includes a brush roller (a supply member) contacting a solid lubricant in a bar shape and supplying a lubricant in a powdered state, scraped off the solid lubricant by rubbing the solid lubricant, to a photoconductor belt or an intermediate transfer belt (a lubricant supplying target). The solid lubricant is held with a solid lubricant holding member, and a spring (a biasing device) is in contact with the solid lubricant holding member. The solid lubricant is pressed against the brush roller by the biasing force of the spring. When the brush roller is rotated, the solid lubricant contacting the brush roller is rubbed by the brush roller and thereby, a lubricant scraped off the solid lubricant and adhered to the brush roller is coated on the surface of the photoconductor belt or the intermediate transfer belt. Further, a lubricant equalization blade is provided in the lubricant supply device. The lubricant equalization blade presses and spreads the lubricant on the surface of the photoconductor belt or the intermediate transfer belt so that a lubricant layer uniform in thickness is formed on the surface of the photoconductor belt or the intermediate transfer belt. 
       FIG. 1  is a partially enlarged diagram illustrating the principal part of a pressing mechanism generally adopted in a background lubricant supply device.  FIG. 1  illustrates the pressing mechanism viewed from the direction orthogonal to both of the longitudinal direction of a solid lubricant  262  (the left-to-right direction in figure) and the direction in which the solid lubricant  262  is pressed against a supply member (the vertical direction in figure), and in figure, only the part of the pressing mechanism at one end side in the longitudinal direction of the solid lubricant  262  is illustrated. The structure of the pressing mechanism at the other end side of the solid lubricant  262  is substantially the same as that of the part of the pressing mechanism illustrated in figure. 
     Generally, in the background lubricant supply device, both side end parts in the longitudinal direction of the solid lubricant  262  are biased by individual springs  263  in the direction in which the solid lubricant  262  is pressed against the supply member and thereby the solid lubricant  262  is pressed against the supply member. Although detailed description is not made in the above-described JP Publication, the lubricant supply device of the above-described JP Publication is similarly constructed. In such a structure that both side end parts in the longitudinal direction of the solid lubricant  262  are biased with the individual springs  263 , there has been a problem that the solid lubricant  262  cannot be evenly pressed against the supply member in the longitudinal direction of the solid lubricant due to unevenness in the biasing forces of the springs  263 . 
     More specifically, in the initial stage wherein the heights of both side end parts in the longitudinal direction of the solid lubricant  262  are equal, by suppressing the production error in the springs  263  as much as possible, it might be possible to almost eliminate the difference between the biasing forces of the springs  263 . Accordingly, when it is in the initial stage, it might be possible to press the solid lubricant  262  against the supply member almost evenly in the longitudinal direction of the solid lubricant  262 . However, it is extremely difficult to completely eliminate the production error in the springs  263  and a difference might exist between the biasing forces of the springs  263 . When even a slight difference exists between the biasing forces of the springs  263 , as the solid lubricant  262  is scraped off with the supply member, the heights at both side end parts in the longitudinal direction of the solid lubricant  262  become different from each other. In consequence, over time, the elongation amounts of the springs  263  gradually differ from each other and the difference between the biasing forces of the springs  263  increases. Consequently, even if the difference between the biasing forces of the springs  263  has been very small and the solid lubricant  262  has been pressed against the supply member almost evenly in the initial stage, over time, the difference in the biasing forces of the springs  263  increases and thereby it becomes impossible to press the solid lubricant  262  evenly against the supply member. 
     If it becomes impossible to press the solid lubricant  262  evenly against the supply member as described above, unevenness is generated in the lubricant adhered on the surface of a lubricant supplying target, and a deviation is generated in the lubricating property given by the lubricant on the lubricant supplying target. Consequently, it becomes impossible to obtain a desired lubricating property. In the lubricant supply device described in the above-described JP Publication, as described above, the lubricant equalization blade is provided to reduce the unevenness in the lubricant adhered on the surface of the lubricant supplying target. However, the lubricant adhered on the surface of the lubricant supplying target unevenly in the longitudinal direction of the solid lubricant  262  cannot be pressed and spread sufficiently evenly only by pressing and spreading the lubricant adhered on the surface of the lubricant supplying target with the lubricant equalization blade, so that the unevenness in the lubricant cannot be sufficiently reduced. 
     The above-described problem is not limited to the structure supplying a lubricant scrapped off the solid lubricant  262  by the supply member such as a brush roller to the lubricant supplying target, and it similarly occurs in the structure causing the lubricant supplying target to directly contact the solid lubricant  262  and thereby scraping a lubricant off the solid lubricant  262  by the lubricant supplying target. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in view of the above-discussed and other problems and addresses the above-discussed and other problems. 
     Preferred embodiments of the present invention provide a novel lubricant supply device capable of pressing a solid lubricant evenly against a supply member, an image forming apparatus using the lubricant supply device, and a pressing device applicable to the lubricant supply device. 
     The preferred embodiments of the present invention further provide a novel lubricant supply device capable of pressing a solid lubricant evenly against a lubricant supplying target, an image forming apparatus using the lubricant supply device, and a pressing device applicable to the lubricant supply device. 
     The preferred embodiments of the present invention further provide a novel pressing device capable of making smaller the amount of change over time in the pressing force when pressing a pressing target, such as a solid lubricant, etc., against a lubricant supplying target. 
     According to an embodiment of the present invention, a lubricant supply device includes a solid lubricant, a supply member contacting and rubbing the solid lubricant and thereby scraping a lubricant off the solid lubricant and supplying the lubricant to a lubricant supplying target, and a pressing mechanism pressing the solid lubricant against the supply member. The pressing mechanism includes a biasing device, and a plurality of pressing members receiving a biasing force of the biasing device and thereby pressing places of the solid lubricant at symmetrical positions with respect to a center of a contact part of the solid lubricant contacting the supply member, respectively. 
     According to another embodiment of the present invention, an image forming apparatus includes an image bearing member and a solid lubricant supplying device supplying a lubricant to the surface of the image bearing member. The image forming apparatus eventually transfers an image on the image bearing member onto a recording member to form the image on the recording member. The lubricant supply device includes a solid lubricant, a supply member contacting and rubbing the solid lubricant and thereby scraping a lubricant off the solid lubricant and supplying the lubricant to the image bearing member, and a pressing mechanism pressing the solid lubricant against the supply member. The pressing mechanism includes a biasing device, and a plurality of pressing members receiving a biasing force of the biasing device and thereby pressing places of the solid lubricant at symmetrical positions with respect to a center of a contact part of the solid lubricant contacting the supply member, respectively. 
     According to still another embodiment of the present invention, a pressing device pressing an object to be pressed in a predetermined direction is provided. The pressing device includes a biasing device, and a plurality of pressing members receiving a biasing force of the biasing device and thereby pressing places of the object to be pressed at symmetrical positions with respect to a center of a pressed part of the object to be pressed, respectively. 
     In the above-described embodiments of the present invention, the pressing forces of a plurality of pressing members are given with the biasing force of a single biasing device. The biasing force of the single biasing device acts equally to the pressing members, so that the pressing forces of the pressing members pressing a solid lubricant respectively become equal to each other. The pressing members press the places of the solid lubricant at symmetrical positions with respect to the center of a contact part of the solid lubricant contacting a supply member or a lubricant supplying target, so that the solid lubricant can be pressed evenly against the supply member or the lubricant supplying target. Consequently, not only in the initial stage but also after the solid lubricant has been gradually scraped with the supply member or the lubricant supplying target and decreased, the solid lubricant can be evenly pressed against the supply member or the lubricant supplying target. 
     According to still another embodiment of the present invention, a pressing device pressing an object to be pressed in a predetermined direction includes a biasing device and a pressing mechanism receiving a biasing force of the biasing device and thereby pressing the object to be pressed. The pressing mechanism includes a biasing force transmission device transmitting the biasing force of the biasing device to the object to be pressed such that an amount of change in a pressing force pressing the object to be pressed relative to an amount of change over time in the biasing force of the biasing device is smaller than in a structure pressing the object to be pressed such that the biasing force of the biasing device and the pressing force pressing the object to be pressed agree. 
     In the embodiment of the present invention described immediately above, as compared with a background pressing mechanism pressing an object to be pressed such that the biasing force of a biasing device and the pressing force pressing the object to be pressed agree, the amount of change in the pressing force pressing the object to be pressed relative to the amount of change over time in the biasing force of the biasing device is smaller, so that the amount of change over time in the pressing force when pressing the object to be pressed against a lubricant supplying target can be made smaller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A more complete appreciation of the present invention and many of the attended advantages thereof will be readily obtained as the present invention becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings, wherein: 
         FIG. 1  is a partially enlarged diagram illustrating the principal part of a pressing mechanism generally adopted in a background lubricant supply device; 
         FIG. 2  is a schematic diagram illustrating an exemplary overall structure of a printer as an image forming apparatus according to an embodiment of the present invention; 
         FIG. 3  is a schematic diagram illustrating an exemplary structure of one of the image formation units provided in the printer; 
         FIG. 4  is a partially enlarged diagram illustrating the principal part of a pressing mechanism provided in the printer; 
         FIG. 5  is a graph illustrating a change over time in the pressing force of a solid lubricant when compared between the pressing mechanism of the present invention and the background pressing mechanism; 
         FIG. 6  is a diagram for explaining the force acting on a movable member of the pressing mechanism of the present invention; 
         FIG. 7  is a cross section illustrating states of an example of the pressing mechanism when a brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 8  is a cross section illustrating states of another example of the pressing mechanism when a brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 9  is a cross section illustrating states of still another example of the pressing mechanism including a regulation when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 10  is a cross section illustrating states of still another example of the pressing mechanism when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 11  is a cross section illustrating states of another example of the pressing mechanism including a solid lubricant in a square shape when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 12  is a cross section illustrating states of still another example of the pressing mechanism including the solid lubricant in a square shape when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 13  is a cross section illustrating states of still another example of the pressing mechanism including the solid lubricant in a square shape when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 14  is a cross section illustrating states of still another example of the pressing mechanism including the solid lubricant in a square shape when the brush roller is in the stationary state and when the brush roller is in the driven state; 
         FIG. 15A  is a cross section illustrating still another example of the pressing mechanism in the initial stage; 
         FIG. 15B  is a cross section illustrating the example of the pressing mechanism of  FIG. 15A  when the solid lubricant has been used up; 
         FIG. 16  is a diagram for explaining setting a lubricant holding member holding the solid lubricant in an accommodation case in the pressing mechanism of  FIG. 15A  and  FIG. 15B ; 
         FIG. 17A  is a partially enlarged diagram illustrating the principal part of still another example of the pressing mechanism; 
         FIG. 17B  is a diagram illustrating the internal structure of the pressing mechanism of  FIG. 17A ; 
         FIG. 18  is a diagram illustrating a state before the solid lubricant is set to the pressing mechanism in an example that the pressing mechanism is mounted on the main body side of an apparatus; 
         FIG. 19A  is a diagram illustrating a state after the solid lubricant has been set to the pressing mechanism in the example of  FIG. 18  when viewed from the direction orthogonal to the longitudinal direction of the solid lubricant; 
         FIG. 19B  is a diagram illustrating the state in  FIG. 19A  viewed from the longitudinal direction of the solid lubricant; 
         FIG. 20A  is a diagram illustrating a state when the solid lubricant has been used up in the example of  FIG. 18  viewed from the direction orthogonal to the longitudinal direction of the solid lubricant; 
         FIG. 20B  is a diagram illustrating the state in  FIG. 20A  viewed from the longitudinal direction of the solid lubricant; 
         FIG. 21A  is a cross section illustrating still another example of the pressing mechanism when the brush roller is in the stationary state; and 
         FIG. 21B  is a cross section illustrating the example of the pressing mechanism of  FIG. 21A  when the brush roller is in the driven state. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring now to the drawings, wherein like reference numerals designate identical or corresponding parts throughout the several views, preferred embodiments of the present invention are described. 
       FIG. 2  is a schematic diagram illustrating an exemplary overall structure of a printer  1  as an image forming apparatus according to an embodiment of the present invention. 
     Image formation units  2 A,  2 B,  2 C and  2 D provided with photoconductors serving as image bearing members are installed inside of the main body of the printer  1  detachably from the main body, respectively. A transfer device  3  provided with a transfer belt  31  spanned around a plurality of rollers is arranged substantially in the center part of the main body. The transfer belt  31  is driven to rotate in the direction indicated by an arrow “A” in figure. The image formation units  2 A,  2 B,  2 C and  2 D are located above the transfer belt  31 , respectively, and are arranged such that respective photoconductors  5  contact the surface of the transfer belt  31 . Further, development devices  10 A,  10 B,  10 C and  10 D, each using toner of a different color, are provided to correspond to the image formation units  2 A,  2 B,  2 C and  2 D. The image formation units  2 A,  2 B,  2 C and  2 D are substantially the same in structure, and the image formation unit  2 A forms images corresponding to magenta, the image formation unit  2 B forms images corresponding to cyan, the image formation unit  2 C forms images corresponding to yellow, and the image formation unit  2 D forms images corresponding to black. 
     A writing unit  6  is arranged above the image formation units  2 A,  2 B,  2 C and  2 D. The writing unit  6  includes four light sources for respective colors, using laser diodes (LDs), respectively. The writing unit  6  further includes a polygon scanner including a polygon mirror having six surfaces and a polygon motor. An optical system including an fθ lens and a long cylindrical lens is arranged in the optical path of each light source. The laser light emitted from each laser diode is deflected with the polygon scanner to scan and illuminate the surface of the corresponding photoconductor  5 . 
     A duplex unit  7  is arranged below the transfer belt  31 . Further, a reversing unit  8  is installed at the left side in figure of the main body of the printer  1 . The reversing unit  8  reverses a transfer sheet (recording member) on which an image has been formed, and discharges the transfer sheet or conveys the transfer sheet to the duplex unit  7 . The duplex unit  7  includes a pair of conveyance guiding plates  45   a  and  45   b  and plural pairs (four pairs, in this example) of conveyance rollers  46 . In the duplex copying mode in which images are formed on both sides of a transfer sheet, after forming an image on one side of the transfer sheet, the transfer sheet is conveyed to a reversing conveyance path  54  of the reversing unit  8 , and the transfer sheet is then reversed toward a sheet feeding part described later. The reversing unit  8  reverses a transfer sheet for forming images on both sides thereof and conveys the transfer sheet to the duplex unit  7  as described above, or discharges a transfer sheet on which an image has been formed on one side thereof without reversing the transfer sheet so as to be discharged with the side carrying the image faced upward or after reversing the transfer sheet so as to be discharged with the side carrying the image faced downward. Sheet feeding cassettes  11  and  12  are provided in the sheet feeding part, and further, sheet separating/feeding devices  55  and  56  separating transfer sheets one from the other and feeding the separated transfer sheet are provided for respective sheet feeding cassettes  11  and  12 . 
     A fixing device  9 , which fixes an image transferred onto a transfer sheet to the transfer sheet, is provided between the transfer belt  31  and the reversing unit  8 . A reverse discharging path  20  is formed at the downstream side of the fixing device  9  in the sheet conveyance direction, separating from the conveyance path to the reversing unit  8 . The transfer sheet conveyed to the reverse discharging path  20  is discharged onto a discharge tray  26  with a discharging roller pair  25 . The sheet feeding cassettes  11  and  12  are provided in the bottom part of the main body of the printer  1 , one above the other, and accommodate transfer sheets of different sizes. Further, a manual sheet feed tray  13  is provided to the right side surface of the main body in figure. The manual sheet feed tray  13  is configured to open in the direction of the arrow “B” in figure, and a transfer sheet can be manually fed in by opening the manual sheet feed tray  13 . 
       FIG. 3  is a schematic diagram illustrating an exemplary structure of one of the image formation units  2 A,  2 B,  2 C and  2 D. 
     Each of the image formation units  2 A,  2 B,  2 C and  2 D includes the photoconductor  5  on which a latent image is formed, a charging device  14  uniformly charging the surface of the photoconductor  5 , and a cleaning device  15  cleaning the surface of the photoconductor  5 . 
     As the material for the photoconductor  5 , a material having optical conductivity is used, for example, an amorphous metal such as an amorphous silicon, an amorphous selenium, etc., and an organic compound such as a bisazo pigment, a phthalocyanine pigment, etc. Considering environmental protection and processing after the photoconductor  5  has been used, an OPC photoconductor using an organic compound is preferable. 
     For the charging device  14 , any of the corona method, the roller method, the brush method, and the blade method may be used. In this example, the roller method is used in the charging device  14 . The charging device  14  includes a charging roller  141 , a charging roller cleaning brush  142 , which is in contact with the charging roller  141  to clean the charging roller  141 , and an electric source, not shown, which is connected with the charging roller  141 . The charging device  14  uniformly charges the surface of the photoconductor  5  by applying high voltage to the charging roller  141 . 
     The cleaning device  15  includes a cleaning blade  151  contacting the photoconductor  5 , and a lubricant coating device  16  serving as a lubricant supply device scraping a solid lubricant  162  and supplying a lubricant, scrapped off the solid lubricant  162  in a fine powder form, to the surface of the photoconductor  5  as a lubricant supplying target, at the upstream side of the cleaning blade  151  in the direction in which the surface of the photoconductor  5  moves. The detail of the lubricant coating device  16  will be described later. Toner remaining on the surface of the photoconductor  5  after completing the primary transfer is collected from the surface of the photoconductor  5  by the lubricant coating device  16 , and at the same time, the lubricant is coated on the surface of the photoconductor  5 . Thereafter, the toner still remaining on the surface of the photoconductor  5  is scraped off with the cleaning blade  151 . In this embodiment, the lubricant coating device  16  is housed in the cleaning device  15 . However, the lubricant coating device  16  may be constructed in a different unit separately from the cleaning device  15 . 
     Each of the development devices  10 A,  10 B,  10 C and  10 D includes a development roller opposing the photoconductor  5 , a screw conveying developer while stirring the developer, a toner density sensor, etc. In this embodiment, two-component developer including toner and magnetic carriers is used for the developer. Therefore, the development roller includes a sleeve configured to rotate and a magnet fixedly arranged inside of the sleeve. Toner is replenished to each of the development devices  10 A,  10 B,  10 C and  10 D from a toner replenishment device, not shown, according to an output of the toner density sensor. For the magnetic carriers, generally, a core material itself or a core material having a covering layer is used. In this embodiment, a carrier using a ferrite or a magnetite as the core material and covered by a resin layer is used. The particle diameter of the core material is about 20-65 μm, preferably about 30-60 μm. For the resin used for covering the core material, styrene resin, acrylic resin, fluorine resin, silicone resin, or a mixture or copolymer of those resins may be used. The covering layer may be formed by coating the resin on the surface of the core material particle using a known method such as the spraying method, the dipping method, etc. 
     Now, the operation of the printer  1  is described. 
     By starting an image forming operation, the photoconductors  5  respectively rotate in the clockwise direction in figure. The surfaces of the photoconductors  5  are uniformly charged with the charging rollers  141 , and thereafter, laser lights corresponding to respective colors are illuminated on the charged surfaces of the photoconductors  5  by the writing unit  6 . A laser light corresponding to an image of magenta is illuminated on the surface of the photoconductor  5  of the image formation unit  2 A, a laser light corresponding to an image of cyan is illuminated on the surface of the photoconductor  5  of the image formation unit  2 B, a laser light corresponding to an image of yellow is illuminated on the surface of the photoconductor  5  of the image formation unit  2 C, and a laser light corresponding to an image of black is illuminated on the surface of the photoconductor  5  of the image formation unit  2 D. Thereby, latent images corresponding to image data of respective colors are formed on the surfaces of the photoconductors  5 . The latent images on the photoconductors  5  arrive at positions opposing the development devices  10 A,  10 B,  10 C and  10 D with rotation of the photoconductors  5 , where the latent images are developed with toners of magenta, cyan, yellow and black into toner images of respective colors. 
     On the other hand, a transfer sheet is fed from the sheet feeding cassette  11  or  12  by the corresponding sheet separating/feeding device  55  or  56 , and the transfer sheet is conveyed in the timing to match with the toner images formed on the photoconductors  5  by a registration roller pair  59  provided immediately before the transfer belt  31  in the direction in which the transfer sheet is conveyed. The transfer sheet is charged to the positive polarity by a sheet adsorbing roller  58  provided in the vicinity of the entrance of the transfer belt  31  and thereby the transfer sheet is electrostatically adsorbed to the surface of the transfer belt  31 . While the transfer sheet is being conveyed in the state of being adsorbed to the transfer belt  31 , the toner images of magenta, cyan, yellow and black are sequentially transferred onto the transfer sheet and thereby a full color toner image in which four color images have been superimposed is formed on the transfer sheet. The transfer sheet is then conveyed to the fixing device  9 , where heat and pressure are applied to the transfer sheet and thereby the full color toner image is melted and fixed to the transfer sheet. Thereafter, according to a designated mode, the transfer sheet is discharged onto the discharge tray  26  after passing the reverse discharging path  20 , or conveyed from the fixing device  9  straightly to be directly discharged after passing the reversing unit  8 . When the duplex mode has been selected, the transfer sheet is conveyed into the reverse conveyance path in the reversing unit  8 , reversed to the duplex unit  7 , and then conveyed to the image formation part where the image formation units  2 A,  2 B,  2 C and  2 D are provided, and after an image has been formed on the backside of the transfer sheet at the image formation part, the transfer sheet is discharged. 
     Next, the structure of the lubricant coating device  16  is described. 
     The lubricant coating device  16  in this embodiment includes, as illustrated in  FIG. 3 , a brush roller  161  serving as a supply member, a solid lubricant  162  in a rod shape long in the direction orthogonal to the sheet surface, and a pressing mechanism  163  serving as a pressing device. The rotation direction of the brush roller  161  is the direction in which the brush roller  161  is caused to rotate by rotation of the photoconductor  5 . The brush roller  161  is formed of a resin material such as nylon, acryl, etc., the volume resistivity of which has been adjusted to be in the range from 1×10 3  Ω·cm to 1×10 8  Ωcm by adding a resistance controlling material such as carbon black, etc. The solid lubricant  162  is pressed against the brush roller  161  by the pressing mechanism  163 . As the material for the solid lubricant  162 , fatty acid metallic salts may be used, such as, lead oleate, zinc oleate, copper oleate, zinc stearate, cobalt stearate, iron stearate, copper stearate, zinc palmitate, copper palmitate, zinc linoleate, etc. Among those fatty acid metallic salts described above, zinc stearate is most preferable. Further, the solid lubricant  162  made in a solid form by filling zinc stearate, calcium stearate, etc. in a solid form molding body may be also used. 
     The brush roller  161  is driven to rotate and thereby a lubricant is scraped off the solid lubricant  162  in minute particles, and the lubricant in minute particles is coated on the surface of the photoconductor  5  by the brush roller  161 . Thereafter, due to contact of the surface of the photoconductor  5  and the cleaning blade  151 , the coated lubricant on the surface of the photoconductor  5  is pressed and spread in a thin film state. Thereby, the friction coefficient of the surface of the photoconductor  5  decreases. Because the film of the lubricant adhered to the surface of the photoconductor  5  is very thin, it never occurs that the film of the lubricant hampers charging of the photoconductor  5  with the charging device  14 . 
       FIG. 4  is a partially enlarged diagram illustrating the principal part of the pressing mechanism  163  in this embodiment.  FIG. 4  illustrates the pressing mechanism  163  viewed from the direction orthogonal to both of the longitudinal direction of the solid lubricant  162  (the left-to-right direction in figure) and the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the vertical direction in figure), and in figure, only the part of the pressing mechanism  163  at one end side in the longitudinal direction of the solid lubricant  162  is illustrated. The structure of the part of the pressing mechanism  163  at the other end side of the solid lubricant  162  is substantially the same as that of the part of the pressing mechanism  163  illustrated in figure. 
     In this embodiment, a lubricant holding member  162 A holding the part of the solid lubricant  162  on the opposite side of the surface contacting the brush roller  161  (the lower side surface in figure) is provided. The lubricant holding member  162 A holds the solid lubricant  162  through the longitudinal direction thereof. A movable member  163 A serving as a pressing member is attached to each end part in the longitudinal direction of the lubricant holding member  162 A. One end (the attaching end) of the movable member  163 A is rotatably attached to the lubricant holding member  162 A, and the other end (the rotating end) of the movable member  163 A is rotatable in the direction of the arrow “C” in figure around an attachment position  163 B of the lubricant holding member  162 A where the movable member  163 A is attached. End parts of a spring  163 C serving as a biasing device are attached to respective movable members  163 A. Each movable member  163 A obtains from the spring  163 C a biasing force directing toward the center in the longitudinal direction of the lubricant holding member  162 A, e.g., in the direction of the arrow “D” in figure. Due to this biasing force of the spring  163 , the rotating end of the movable member  163 A is biased in the direction of separating from the lubricant holding member  162 A as illustrated in  FIG. 4 . 
     The lubricant holding member  162 A holding the solid lubricant  162  is attached to the cleaning device  15  in the state that the movable members  163 A and the spring  163 C have been attached. When attaching the lubricant holding member  162 A to the cleaning device  15 , the lubricant holding member  162 A is arranged, as illustrated in  FIG. 3 , between a casing internal wall  164  of the cleaning device  15  as a fixed member and the brush roller  161  in the state that the rotating ends of the movable members  163 A have been rotated in the directions of approaching the lubricant holding member  162 A while resisting against the biasing force of the spring  163 C. With this configuration, the movable members  163 A at both side ends of the lubricant holding member  162 A receive the biasing force of the spring  163 C and thereby press the casing internal wall  164  with even forces, so that the solid lubricant  162  held by the lubricant holding member  162 A is pressed against the brush roller  161 . Accordingly, the solid lubricant  162  is pressed against the brush roller  161  evenly in the longitudinal direction of the solid lubricant  162 . Consequently, the quantity of the lubricant scraped off the solid lubricant  162  by the brush roller  161  as the brush roller  161  rotates and rubs the solid lubricant  162  is made even in the longitudinal direction of the solid lubricant  162 , so that the lubricant can be coated on the surface of the photoconductor  5  evenly in the longitudinal direction thereof. 
     Further, the pressing mechanism  163  in this embodiment is advantageous in the following point also as compared with the background pressing mechanism illustrated in  FIG. 1 . 
       FIG. 5  is a graph illustrating a change over time in the pressing force of the solid lubricant  162  when compared between the pressing mechanism  163  in this embodiment and the background pressing mechanism of  FIG. 1 . The vertical axis indicates the ratio of the pressing force relative to an initial pressing force, and the horizontal axis indicates the height of the solid lubricant  162  (the dimension of the solid lubricant  162  in the direction in which the solid lubricant  162  is pressed against the brush roller  161 ). 
     In the background pressing mechanism of  FIG. 1 , as the solid lubricant  162  decreases in height by being used over time, the pressing force pressing the solid lubricant  162  gradually decreases. Therefore, the quantity of the lubricant scraped off the solid lubricant  162  by the brush roller  161  decreases over time, so that the change in the quantity of the lubricant supplied to the surface of the photoconductor  5  from the initial stage over time is relatively large. In contrast, in the pressing mechanism  163  in this embodiment, even if the solid lubricant  162  has changed in height by being used over time, decrease in the pressing force pressing the solid lubricant  162  can be suppressed, so that the change in the quantity of powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed relatively small. 
     The reason that the above-described result can be obtained is as described below. 
     Generally, as the overall length of a spring is longer, the change in the biasing force of the spring during the time from the initial stage until when the solid lubricant  162  has been used up can be managed to be small relative to the amount of change in elongation of the spring during that time. In the background pressing mechanism of  FIG. 1 , as illustrated in figure, the spring  263  is set in the compressed state and it is necessary that the biasing (pushing out) direction of the spring  263  and the direction in which the solid lubricant  262  is pressed against a brush roller (supply member) agree. In this configuration, as the overall length of the spring  263  is longer, it is more difficult to cause the biasing direction of the spring  263  and the direction in which the solid lubricant  262  is pressed against the brush roller (supply member) to be agreed, so that there is a limit in increasing the overall length of the spring  263 . In addition, in the background pressing mechanism of  FIG. 1 , an arrangement space corresponding to the length of the spring  263  must be secured in the diameter direction of the brush roller, leading to increasing the size of an apparatus in which the pressing mechanism is installed. Because of these reasons, in the background pressing mechanism of  FIG. 1 , the spring that is relatively short must be used, so that as indicated in  FIG. 5 , the change over time in the biasing force of the spring becomes relatively large. 
     In contrast, in the pressing mechanism  163  in this embodiment, as illustrated in  FIG. 4 , the spring  163 C is set in the elongated state, and the solid lubricant  162  is pressed against the brush roller  161  by the biasing force (pulling force) of the spring  163 C. Therefore, even if the overall length of the spring  163 C is increased, the problem occurred in the background pressing mechanism does not occur. Further, the spring  163 C is set such that the longitudinal direction of the spring  163 C agrees with the longitudinal direction of the solid lubricant  162 , i.e., the axial direction of the brush roller  161 . Accordingly, even if the overall length of the spring  163 C is increased, it never occurs that the arrangement space for installing the spring  163 C increases in the diameter direction of the brush roller  161 , so that it is not necessary to increase the size of an apparatus in which the pressing mechanism  163  is installed. Therefore, in the pressing mechanism  163  in this embodiment, the spring  163 C that is much longer than the spring used in the background pressing mechanism is used. Consequently, the change over time in the biasing force of the spring  163 C can be suppressed small as illustrated in  FIG. 5 . 
     Further, it owes to the following structure adopted in this embodiment that the effect that the change in the quantity of the powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed small as illustrated in  FIG. 5  is obtained. 
     That is, in this embodiment, it is constructed such that in response to that the solid lubricant  162  decreases due to being rubbed by the brush roller  161 , the distance in the direction in which the solid lubricant  162  is pressed against the brush roller  161  between the point of force of each movable member  163 A receiving the biasing force of the spring  163 C and the point of action where the movable member  163 A contacts the casing internal wall (contacted part)  164  changes, which will be explained more in detail below. 
       FIG. 6  is a diagram for explaining the force acting on the movable member  163 A of the pressing mechanism  163 . 
     In this embodiment, the movable member  163 A is configured to freely rotate around the attachment position  163 B with the attachment position  163 B serving as the fulcrum. Here, the point where the movable member  163 A contacts the casing internal wall (contacted part)  164  is regarded as the point of action, and the length from the fulcrum to the point of action is denoted by the symbol “L”. The distance between the fulcrum and the point of action in the direction in which the solid lubricant  162  is pressed is denoted by the symbol “h”. The angle formed by the direction connecting the fulcrum and the point of action and the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the vertical direction in figure) is expressed by (π−θ). Further, the point where the movable member  163 A receives a biasing force “F” from the spring  163 C is regarded as the point of force. The length from the fulcrum to the point of force is denoted by the symbol “I”, and the angle formed by the direction connecting the fulcrum and the point of force and the direction of the biasing force F is denoted by φ. At this time, a force N generated at the point of action, that is, a pressing force N pressing the solid lubricant  162 , is expressed as follows; N=(I/L)×F×sin φ×cos θ. 
     Here, in this embodiment, if the solid lubricant  162  decreases by being rubbed, the position of the point of force shifts toward right in figure and thereby the spring  163 C is shrank, leading to decreasing in the biasing force F of the spring  163 C. Consequently, if the solid lubricant  162  decreases by being rubbed, the biasing force F changes the force N generated at the point of action, i.e., the pressing force N, to be smaller. However, in this embodiment, the amount of decrease in the biasing force F as compared to the amount of decrease in the solid lubricant  162  (the amount of increase in the distance h) is much smaller than in the background pressing mechanism illustrated in  FIG. 1 . Accordingly, according to this embodiment, the amount of decrease in the pressing force N relative to the amount of decrease in the solid lubricant  162  (the amount of increase in the distance h) can be suppressed relatively small. 
     Further, if the solid lubricant  162  decreases by being rubbed by the brush roller  161 , the distance h increases correspondingly to the amount of decrease in the solid lubricant  162 , so that the angle (π−θ) formed by the direction connecting the fulcrum and the point of action and the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the vertical direction in figure) decreases. That is, the angle θ increases. Accordingly, because cos θ decreases as the sold lubricant  162  decreases by being rubbed, the force N generated at the point of action (the pressing force N) decreases correspondingly. However, in this embodiment, it is constructed such that if the solid lubricant  162  decreases by being rubbed, the angle φ formed by the direction connecting the fulcrum and the point of force and the direction of the biasing force F increases. Therefore, as the solid lubricant  162  decreases by being rubbed, sin φ increases, and the force N generated at the point of action (the pressing force N) increases correspondingly. Consequently, the decrease in the force N due to the decrease in cos φ can be offset by the increase in the force N due to the increase in sin φ. 
     Furthermore, in this embodiment, as illustrated in  FIG. 4 , a contacting part of the movable member  163 A, that may contact the casing internal wall  164 , is formed in a curved shape. Thereby, if the solid lubricant  162  decreases by being rubbed, the contacting place of the contacting part of the movable member  163 A, that contacts the casing internal wall  163 A, gradually changes. Accordingly, in this embodiment, if the solid lubricant  162  decreases by being rubbed, the length L from the fulcrum to the point of action increases. Here, increasing in the length L from the fulcrum to the point of action causes the force N generated at the point of action (i.e., the pressing force N) to be changed smaller. However, increasing in the length L from the fulcrum to the point of action causes the angle θ to be made smaller. Accordingly, the ratio of decrease in cos θ decreasing as the solid lubricant  162  decreases by being rubbed can be suppressed relatively small. 
     As described above, if the solid lubricant  162  decreases by being rubbed and thereby the distance h increases, based upon this, the length L increases, the biasing force F decreases, sin φ increases, and cos θ decreases. However, by suppressing the ratio of decrease in the biasing force F small as compared with the background pressing mechanism as described above and at the same time by suppressing the ratio of decrease in cos θ by adopting the structure that the length L from the fulcrum to the point of action gradually increases, the ratio of decrease in the pressing force N can be suppressed in a comprehensive manner as compared with the background pressing mechanism. Thus, according to this embodiment, even when the solid lubricant  162  has decreased by being rubbed, the amount of change in the force N generated at the point of action (the pressing force N) can be made relatively small, so that the effect that the change in the quantity of powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed small is obtained. 
     To effectively transmit the biasing force F to the point of action, it is preferable that the angle θ is set in the range close to 90° and the angle θ is set in the range close to 0′. However, as the angle θ is closer to 0′, the length L must be made longer, so that because of the relation to the layout of an apparatus in which the pressing mechanism  163  is installed, the angle θ cannot be set close to 0° too much. 
     Further, the pressing mechanism  163  in this embodiment is advantageous in the following point also as compared with the background pressing mechanism illustrated in  FIG. 1 . 
     In the background pressing mechanism also, as described with respect to this embodiment, a lubricant holding member holding the solid lubricant  262  is attached to the cleaning device  15  in the state that two springs  263  have been attached to the lubricant holding member. In the background pressing mechanism, when attaching the lubricant holding member to the cleaning device  15 , it is necessary that free ends of the springs  263  fixed to both side end parts in the longitudinal direction of the solid lubricant  262  are positioned at predetermined attaching positions on the casing internal wall  164  of the cleaning device  15 , respectively. The free ends of the springs  263  are easily dislocated in the direction in which the springs  263  are positioned only by receiving small forces, so that it is not so easy to position the free ends of the springs  263  at the predetermined attaching positions and the workability in the attaching operation is inferior. In contrast, in the pressing mechanism  163  in this embodiment, the rotating ends of the movable members  163 A are positioned at predetermined attaching positions when attaching the pressing mechanism  163  to the cleaning device  15 . Because the rotating ends of the movable members  163 A are not easily dislocated in the direction in which the rotating ends of the movable members  163 A are positioned, the workability in the attaching operation is greatly enhanced. 
       FIG. 7  illustrates states of an example of the above-described pressing mechanism  163  when the brush roller  161  is in the stationary state and when the brush roller  161  is in the driven state, the state when the brush roller  161  is in the stationary state being illustrated in the left side part in figure and the state when the brush roller  161  is in the driven state being illustrated in the right side part in figure.  FIG. 7  is a cross section at a virtual plane including both of the direction of the force the solid lubricant  162  receives from the brush roller  161  by being rubbed by the brush roller  161  (the left-to-right direction in figure) and the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the vertical direction in figure). 
     In this embodiment, to regulate the solid lubricant  162  from being dislocated in the direction of the force the solid lubricant  162  receives from the brush roller  161  (the left-to-right direction in figure), two regulation parts  164 A are provided on the casing internal wall  164 . The pressing mechanism  163  is fit between these regulation parts  164 A and thereby the solid lubricant  162  is regulated from being dislocated in the left-to-right direction in figure by being rubbed by the brush roller  161 . 
     Here, in the example illustrated in  FIG. 7 , the casing internal wall  164  serving as the contacted part is flat, and the contacting part of the movable member  163 A contacting the casing internal wall  164  is configured to have a certain width in the direction of the force the solid lubricant  162  receives from the brush roller  161  by being rubbed by the brush roller  161  (the left-to-right direction in figure). Consequently, when the brush roller  161  is in the stationary state, as illustrated in the left side part in  FIG. 7 , the movable member  163 A is in contact with the casing internal wall  164  at the whole area in the widthwise direction (the left-to-right direction in figure) of the contacting part thereof. However, because there exists some gap between the regulation part  164 A and the solid lubricant  162  or the lubricant holding member  162 A holding the solid lubricant  162 , when the brush roller  161  is driven to rotate, the solid lubricant  162  is dislocated in the left-to-right direction in figure by receiving a rubbing force from the brush roller  161 . Consequently, when the brush roller  161  is in the driven state, the movable member  163 A contacts the casing internal wall  164  only at one end part in the widthwise direction of the contacting part thereof as illustrated in the right side part in  FIG. 7 . Thereby, the maximum dislocating amount “D” of the solid lubricant  162  from the state that the brush roller  161  is in the stationary state illustrated in the left side part in  FIG. 7  is as illustrated in figure. 
     As the maximum dislocating amount D is greater, the encroaching amount of the solid lubricant  162  into the brush roller  161  increases and thereby the lubricant larger in quantity than as initially planned is supplied to the photoconductor  5 . Consequently, the consumption amount of the lubricant increases. Further, as the maximum dislocating amount D is greater, the load to the motor driving the brush roller  161  increases, and further, the vibration amount of the brush roller  161  increases and thereby image deterioration due to bounding becomes easy to occur. Furthermore, as the maximum dislocating amount D is greater, coming off and/or falling down of bristles of the brush roller  161  become easy to occur, so that the life of the brush roller  161  becomes shorter. Accordingly, it is desired that the maximum dislocating amount D is small as much as possible. 
     By making the gap between the regulation part  164 A and the solid lubricant  162  or the lubricant holding member  162 A smaller, the maximum dislocating amount D can be made smaller. However, taking into consideration the workability in attaching the solid lubricant  162  and the pressing mechanism  163 , the gap is necessary to be in a certain breadth, so that there is a limit in making the gap smaller. 
       FIG. 8  illustrates states of another example of the pressing mechanism  163  when the brush roller  161  is in the stationary state and when the brush roller  161  is in the driven state. 
     In this example, the casing internal wall  164  as the contacted part with which the movable member  163 A is brought into contact is flat, and the contacting part of the movable member  163 A contacting the casing internal wall  164  is formed in cross section in a spire shape that the center portion thereof in the left-to-right direction in figure protrudes. Thereby, the movable member  163 A contacts the casing internal wall  164  at the spire part thereof when the brush roller  161  is in the stationary state and when the brush roller  161  in the driven state as well. Consequently, the maximum dislocating amount D′ of the solid lubricant  162  when the brush roller  161  is turned into the driven state illustrated in the right side part in  FIG. 8  from the stationary state illustrated in the left side part in  FIG. 8  is as illustrated in figure, which is smaller than the maximum dislocation amount D in the example illustrated in  FIG. 7 . Accordingly, as compared with the example illustrated in  FIG. 7 , the encroaching amount of the solid lubricant  162  into the brush roller  161  is suppressed smaller and thereby it can be suppressed that the consumption amount of the lubricant increases. Further, it can be suppressed that the load to the motor driving the brush roller  161  increases, and also, image deterioration can be suppressed by suppressing the degree of bounding small. Furthermore, coming off and/or falling down of the bristles of the brush roller  161  become harder to occur, so that the life of the brush roller  161  can be made longer. 
       FIG. 9  illustrates states of another example of the pressing mechanism  163  when the brush roller  161  is in the stationary state and when the brush roller  161  is in the driven state. 
     In this example, a regulation part  164 B regulating the contacting part of the movable member  163 A contacting the casing internal wall  164  from being dislocated in the left-to-right direction in figure is provided in the center part of the surface of the casing internal wall  164  in the left-to-right direction in figure. Specifically, the surface of the casing internal wall  164  with which the contacting part of each movable member  163 A is brought into contact is formed to slope toward the center part thereof in the left-to-right direction in figure, and the center part functions as the regulation part  164 B. By providing the regulation part  164 B as described above, the contacting part of each movable member  163 A is regulated from being dislocated in the left-to-right direction in figure by the regulation part  164 B even when the brush roller  161  is in the driven state as illustrated in the right side part in  FIG. 9  and is kept in substantially the same position as that in the stationary state illustrated in the left side part in  FIG. 9 , that is, at the center part in the left-to-right direction in figure. In this example, the maximum dislocating amount D″ of the solid lubricant  162  when the brush roller  161  has been turned into the driven state illustrated in the right side part in  FIG. 9  from the stationary state illustrated in the left side part in  FIG. 9  is as illustrated in figure and is further smaller than the maximum dislocating amount D′ in the example illustrated in  FIG. 8 . Accordingly, as compared with the example illustrated in  FIG. 8 , the encroaching amount of the solid lubricant  162  into the brush roller  161  is suppressed further smaller, and thereby it can be suppressed that the consumption amount of the lubricant increases. Further, it can be further suppressed that the load to the motor driving the brush roller  161  increases, and image deterioration can be also further suppressed by suppressing the degree of bounding small. Furthermore, coming off and/or falling down of the bristles of the brush roller  161  become harder to occur as compared with the example illustrated in  FIG. 8 , so that the life of the brush roller  161  can be made further longer. 
       FIG. 10  illustrates states of another example of the pressing mechanism  163  including a variation of the regulation part regulating the contacting part of the movable member  163 A from being dislocated in the left-to-right direction in figure. 
     A regulation part  164 C as the variation of the regulation part is a hole or groove into which the contacting part of the movable member  163 A is put, that is formed at the center portion in the left-to-right direction in figure of the flat surface of the casing internal wall  164  with which the contacting part of the movable member  163 A is brought into contact. In this variation also, as in the example illustrated in  FIG. 9 , the contacting part of the movable member  163 A is regulated from being dislocated in the left-to-right direction in figure even when the brush roller  161  is in the driven state as illustrated in the right side part in  FIG. 10  and is kept in substantially the same position as that in the stationary state illustrated in the left side part in  FIG. 10 , that is, at the center part in the left-to-right direction in figure. Accordingly, the maximum dislocation amount D″ of the solid lubricant  162  when the brush roller  161  has been put into the driven state illustrated in the right side part in  FIG. 10  from the stationary state illustrated in the left side part in  FIG. 10  is as illustrated in figure and is about the same as the maximum dislocation amount D″ in the example illustrated in  FIG. 9 . Accordingly, the effects obtained in the example illustrated in  FIG. 9  can be similarly obtained. 
     In the above-described examples, to maintain the contacting condition of the brush roller  161  and the solid lubricant  162  substantially constant from the initial stage over time, the contacting part of the solid lubricant  162  contacting the brush roller  161  is formed in the initial state in a shape conforming to the outer circumference of the brush roller  161  (in an arc in cross section) as illustrated in figure. However, the shape of the contacting part of the solid lubricant  162  is not limited to such an arc shape, and may be formed otherwise. For example, as illustrated in  FIG. 11 , a solid lubricant  362  formed in a rectangular shape may be used. In this case also, by making the cross section of the contacting part of the movable member  163 A in a spire shape as illustrated in  FIG. 12 , the maximum dislocating amount D′ of the solid lubricant  362  when the brush roller  161  has been put into the driven state from the stationary state is smaller as compared with the example illustrated in  FIG. 11 . Further, as illustrated in  FIG. 13  and  FIG. 14 , by providing the regulation part  164 B or  164 C at the center part in the left-to-right direction in figure of the surface of the casing internal wall  164 , the maximum dislocating amount D″ of the solid lubricant  362  when the brush roller  161  has been put into the driven state from the stationary state is made further smaller than in the example illustrated in  FIG. 12 . 
     In this embodiment, the description has been made with respect to the case in which the casing internal wall  164  with which the contacting part of the movable member  163 A is brought into contact is flat and the cross section of the contacting part of the movable member  163 A is in a spire shape. However, by making the cross section of the casing internal wall  164  in a spire shape and the contacting part of the movable member  163 A flat, the similar effects can be obtained. In this case, the regulation parts  164 B and  164 C are provided to the flat surface of the contacting part of the movable member  163 A. 
     Further, in this embodiment, the similar effects can be obtained even when the above-described cross section of the movable member  163 A or the casing internal wall  164  is an arc shape instead of the spire shape. 
       FIG. 15A  and  FIG. 15B  are diagrams for explaining another example of the pressing mechanism  163 ,  FIG. 15A  illustrating the state of the pressing mechanism  163  in the initial stage and  FIG. 15B  illustrating the state of the pressing mechanism  163  when the solid lubricant  162  has been used up. 
     In this example, the solid lubricant  162  held by the lubricant holding member  162 A to which the spring  163 C and two movable members  163 A have been attached is accommodated in an accommodation case  165 , and the accommodation case  165  accommodating the solid lubricant  162  held by the lubricant holding member  162 A is attached to the cleaning device  15 . That is, in this example, the solid lubricant  162  held by the lubricant holding member  162 A to which the spring  163 C and two movable members  163 A have been attached is not directly attached to the casing internal wall  164  of the cleaning device  15 , but is attached to the cleaning device  15  in the sate that the solid lubricant  162  held by the lubricant holding member  162 A has been accommodated in the accommodation case  165 . The accommodation case  165  includes, at the surface of the internal wall thereof, a receiving surface  165 A receiving reaction forces applied to the movable members  163 A in the direction (downward in figure) opposite the direction (upward in figure) in which the solid lubricant  162  is pressed against the brush roller  161 , and a surface  165 B regulating the lubricant holding member  162 A from being dislocated in the directions orthogonal to the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the left-to-right and front-to-back directions in figure) by contacting the lubricant holding member  162 A, and further includes an opening part  165 C, which the solid lubricant  162  held by the solid lubricant holding member  162 A can pass, at the part opposing the receiving surface  165 A. 
     In this example, the function of the casing internal wall  164  as the fixed member in the above-described examples is similarly performed by the accommodation case  165 . Further, in this example, the pressing mechanism  163  is constituted of the two movable members  163 A, the spring  163 C, and the accommodation case  165 . 
     When assembling the cleaning device  15 , first, the solid lubricant  162  is attached to the lubricant holding member  162 A to be held, and the spring  163 C and the two movable members  163 A are attached to the lubricant holding member  162 A holding the solid lubricant  162 . Then, the lubricant holding member  162 A is set to the accommodation case  165  as illustrated in  FIG. 16  and thereafter the accommodation case  165  is attached to the cleaning device  15 , or the lubricant holding member  162 A is set to the accommodation case  165  previously attached to the cleaning device  15  or integrally formed with the casing of the cleaning device  15 . Thereafter, the brush roller  161  is built such that the solid lubricant  152  is pushed into the accommodation case  165 . Here, when building the brush roller  161 , the solid lubricant  162  set to the accommodation case  165  is pressed in the direction in which the solid lubricant  162  comes out of the accommodation case  165  by the biasing force of the spring  163 C of the pressing mechanism  163 , so that the workability in building the brush roller  161  is inferior and the productivity decreases. In this example, therefore, a protrusion  166  serving as a dislocation regulation member is provided at an edge part in the longitudinal direction of the opening part  165 C of the accommodation case  165 . The protrusion  166  regulates the lubricant holding member  162 A from being dislocated beyond a predetermined regulation position (the position of the lubricant holding member  162 A illustrated in  FIG. 15B ) in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure) by contacting the lubricant holding member  162 A. 
     Here, the protrusion  166  regulates at least one of the end parts in the longitudinal direction of the lubricant holding member  162 A from being dislocated toward the side of the brush roller  161  beyond the protrusion  166 . If a contacting part  162 B of the lubricant holding member  162 A, which is brought into contact with the protrusion  166 , is positioned at the same height as that of the surface of the solid lubricant  162  on the opposite side of the surface rubbed by the brush roller  161 , that is, the surface of the solid lubricant  162  contacting a solid lubricant holding surface  162 C of the solid lubricant holding member  162 A, the portion of the solid lubricant  162  corresponding to the thickness of the protrusion  166  cannot be used up, so that waste is incurred. 
     Accordingly, in this example, the position of the lubricant holding member  162 A when the lubricant holding member  162 A is regulated by the protrusion  166  from being dislocated in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure), i.e., the predetermined regulation position, is set at the position where the lubricant holding member  162 A is located when the solid lubricant  162  has been used up or at the position shifted in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure), that is, toward the side of the brush roller  161 . Specifically, the contacting part  162 B of the lubricant holding member  162 A is provided at the position shifted from the surface of the solid lubricant  162  on the opposite side of the surface rubbed by the brush roller  161  in the opposite direction (downward direction in figure) of the direction in which the solid lubricant  162  is pressed against the brush roller  161  by a distance greater than the thickness of the protrusion  166  provided at the edge part of the opening part  165 C of the accommodation case  165 . Thereby, when the solid lubricant  162  has been gradually decreased by being rubbed by the brush roller  161  and thereby dislocated together with the lubricant holding member  162 A in the direction in which the solid lubricant  162  is pressed against the brush roller  161 , the contacting part  162 B of the lubricant holding member  162  never contacts the protrusion  166  until the whole part of the solid lubricant  162  is scraped off by the brush roller  161 . Accordingly, the solid lubricant  162  can be used up to the last. Consequently, the effect that the volume of the solid lubricant  162  can be made small is obtained. 
     Next, still another example of the pressing mechanism  163  is described. 
       FIG. 17A  is a partially enlarged diagram illustrating the principal part of the pressing mechanism  163  in this example, and  FIG. 17B  is a diagram illustrating the internal structure of the pressing mechanism  163 . These diagrams illustrate the pressing mechanism  163  viewed from the direction orthogonal to both of the longitudinal direction of the solid lubricant  162  (the left-to-right direction in figure) and the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the vertical direction in figure), and only the part of the pressing mechanism  163  at one end side in the longitudinal direction of the solid lubricant  162  is illustrated. 
     In the pressing mechanism  163  in this example, instead of the above-described two movable members  163 A, two sliding member  463 A are used as the pressing members. The sliding members  463 A are attached to a lubricant holding member  462 A so as to move in the directions in which they come close to each other by receiving the biasing force of the spring  163  serving as the biasing device. Further, the pressing mechanism  163  includes guiding surfaces  464  for guiding movement of the sliding members  463 A. The guiding surfaces  464  may be the casing internal wall  164  of the cleaning device  15  or the receiving surface  165 A of the above-described accommodation case  165 . The guiding surfaces  464  slant such that the sliding members  463 A are dislocated in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure) with movement of the sliding members  463 A. With such a configuration, the two sliding members  463 A press the guiding surfaces  464  with even forces by receiving the biasing force of the spring  163 C, and thereby the solid lubricant  162  held by the lubricant holding member  462 A is pressed against the brush roller  161  as in the above-described examples. Accordingly, the solid lubricant  162  is pressed against the brush roller  161  evenly in the longitudinal direction thereof. Consequently, the lubricant scraped off the solid lubricant  162  by being rubbed by the brush roller  161  with rotation of the brush roller  161  is even in quantity in the longitudinal direction of the solid lubricant  162 , so that the lubricant can be evenly coated on the surface of the photoconductor  5 . 
     In this example also, as in the above-described examples, the spring  163 C that is much longer than the spring used in the background pressing mechanism is used, and thereby the change over time in the biasing force of the spring  163 C can be suppressed small as indicated in  FIG. 5 . Further, according to this example, because the angles of inclination of the guiding surfaces  464  are constant, if the spring  163 C hardly changes in the biasing force thereof from the initial stage over time, then, the pressing forces of the sliding members  463 A pressing the solid lubricant  162  hardly change. Accordingly, the effect that the change in the quantity of powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed small is obtained. 
     As described above, the printer according to this embodiment is an image forming apparatus that includes the photoconductor  5  as an image bearing member and the lubricant coating device  16  as a lubricant supply device supplying a lubricant to the surface of the photoconductor  5  and that eventually transfers an image on the photoconductor  5  onto a transfer sheet as a recording member and thereby forms the image on the transfer sheet. The lubricant coating device  16  includes the solid lubricant  162 , the brush roller  161  as a supply member contacting and rubbing the solid lubricant  162  and supplying a lubricant, scraped off the solid lubricant  162  by rubbing the solid lubricant  162 , to the surface of the photoconductor  5 , and the pressing mechanism  163  pressing the solid lubricant  162  against the brush roller  161 . The pressing mechanism  163  includes the spring  163 C as a biasing device and the movable members  163 A as a plurality of pressing members receiving a biasing force of the spring  163 C and thereby pressing places of the solid lubricant  162  at symmetrical positions with respect to the center of a part of the solid lubricant  162  contacting the brush roller  161 , respectively. With such a structure, the biasing force of the spring  163 C evenly acts on the movable members  163 A, so that the pressing forces of the movable members  163 A pressing the solid lubricant  162  are equal to each other. Accordingly, the solid lubricant  162  can be evenly pressed against the brush roller  161 . The solid lubricant  162  can be evenly pressed against the brush roller  161  not only in the initial stage but also after the solid lubricant  162  has been gradually scraped by the brush roller  161  and thereby decreased over time. The similar effect can be obtained, without using the brush roller  161 , in a construction in which the surface of the photoconductor  5  as a lubricant supplying target is caused to directly contact the solid lubricant  162  and a lubricant is scraped off the solid lubricant  162  by rubbing the solid lubricant  162  with the surface of the photoconductor  5 . 
     Further, in this embodiment, the spring  163 C generates the biasing force in the direction orthogonal to the direction in which the solid lubricant  162  is pressed against the brush roller  161 , and the movable members  163 A press the solid lubricant  152  by converting the direction of the biasing force of the spring  163 C to the direction in which the solid lubricant  162  is pressed against the brush roller  161 . With such a construction, the spring  163 C that is longer than the spring used in the background pressing mechanism can be adopted as described above, and consequently, the change in the quantity of powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed small. 
     Further, in this embodiment, the lubricant holding member  162 A holding the solid lubricant  162  is provided, and it is constructed such that the movable members  163 A press the solid lubricant  162  via the lubricant holding member  162 A. Thereby, the workability in attaching the solid lubricant  162  to an apparatus is enhanced. However, the present invention is not limited to such a structure, and for example, it may be constructed such that the movable members  163 A directly press the solid lubricant  162 . 
     Further, in this embodiment, the spring  163 C is used as the biasing device. However, other biasing devices, for example, an elastic member, such as a rubber, etc., may be used. Furthermore, in this embodiment, a pulling spring is used for the spring  163 C. However, depending upon the structure of the pressing mechanism  163 , a compressed spring may be used. 
     Furthermore, in this embodiment, the description has been made with respect to the structure that the pressing mechanism  163  is mounted at the side of the solid lubricant  162 . However, as illustrated in  FIG. 18 ,  FIG. 19A ,  FIG. 19B ,  FIG. 20A , and  FIG. 20B , it may be configured such that the pressing mechanism  163  is mounted at the main body side of an apparatus and the lubricant holding member  162 A holding the solid lubricant  162  is detachable from the pressing mechanism  163 . In this case, the workability in setting the solid lubricant  162  to the main body of the apparatus is greatly enhanced. That is, when the pressing mechanism  163  is mounted at the side of the solid lubricant  162 , it is necessary to set the solid lubricant  162  and the pressing mechanism  163  while holding down the solid lubricant  162  biased by the pressing mechanism  163  in the direction of separating from the pressing mechanism  163  not to separate from the pressing mechanism  163 , which is extremely inferior in workability. However, if it is constructed such that the pressing mechanism  163  is mounted at the main body side of the apparatus and the lubricant holding member  162 A holding the solid lubricant  162  is detachable from the pressing mechanism  163 , the solid lubricant  162  is set while resisting against the biasing force of the pressing mechanism  163  as illustrated in  FIG. 18  and during that time, it is not necessary to hold down the solid lubricant  162  not to separate from the pressing mechanism  163 . 
     Further, even if it is constructed such that the pressing mechanism  163  is mounted at the main body side of the apparatus, as illustrated in  FIG. 19A  and  FIG. 19B , the solid lubricant  162  can be pressed against the brush roller  161  as with the cases in the above-described examples in which the pressing mechanism  163  is provided at the side of the solid lubricant  162 . 
     Further, in this embodiment, the description has been made with respect to the case that the direction in which the solid lubricant  162  is pressed against the brush roller  161  is downward in the vertical direction except the examples illustrated in  FIG. 15A ,  FIG. 15B ,  FIG. 16 ,  FIG. 17A , and  FIG. 17B . However, it is more advantageous in the following points to make the direction in which the solid lubricant  162  is pressed against the brush roller  161  upward in the vertical direction as in the examples illustrated in  FIG. 15A ,  FIG. 15B ,  FIG. 16 ,  FIG. 17A , and  FIG. 17B . 
     That is, when the direction in which the solid lubricant  162  is pressed against the brush roller  161  is downward in the vertical direction, the pressing force of the solid lubricant  162  to the brush roller  161  is the one in which the own weight of the solid lubricant  162  and the biasing force of the spring  1630  have been added together. In this case, as the solid lubricant  162  decreases by being used over time, the own weight of the solid lubricant  162  decreases, so that the pressing force of the solid lubricant  162  to the brush roller  161  decreases. Further, as the solid lubricant  162  decreases by being used over time, the biasing force of the spring  163 C decreases also, so that the pressing force of the solid lubricant to the brush roller  161  decreases. Accordingly, the pressing force of the solid lubricant  162  to the brush roller  161  gradually decreases by use over time. In contrast, when the direction in which the solid lubricant  162  is pressed against the brush roller  161  is upward in the vertical direction, the pressing force of the solid lubricant  162  to the brush roller  161  is the one in which the own weight of the solid lubricant  162  has been subtracted from the biasing force of the spring  163 C. Therefore, if the solid lubricant  162  decreases by being used over time and thereby the weight of the solid lubricant  152  decreases, it leads to increasing the pressing force of the solid lubricant  162  to the brush roller  161 . Consequently, the portion of the pressing force decreasing due to the decrease in the biasing force of the spring  163 C by use over time and the portion of the pressing force increasing due to the decrease in the own weight of the solid lubricant  162  over time offset each other and thereby the change in the pressing force of the solid lubricant  162  to the brush roller  161  from the initial stage over time can be made relatively small. 
     Further, in this embodiment, as in the example illustrated in  FIG. 15A  and  FIG. 15B , the protrusion  166  is provided as the dislocation regulation member contacting and thereby regulating the lubricant holding member  162 A from being dislocated in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure) beyond the predetermined regulation position. Thereby, even when the hold on the solid lubricant  162  or the lubricant holding member  162 A has been released before setting the solid lubricant  162  to the main body of the apparatus, the situation that the solid lubricant  162  comes off the pressing mechanism  163  due to the biasing force of the pressing mechanism  163  can be prevented. Thus, the troublesome operation of holding the solid lubricant  162 , which is biased by the pressing mechanism  163  in the direction of separating from the pressing mechanism  163 , not to separate from the pressing mechanism  163  becomes unnecessary when setting the solid lubricant  162  to the main body of the apparatus and the workability in setting the solid lubricant  162  to the main body of the apparatus is enhanced. 
     In particular, in this embodiment, as in the example illustrated in  FIG. 15A  and  FIG. 15B , the predetermined regulation position is set at the position where the lubricant holding member  162 A is located when the solid lubricant  162  has been used up or at the position shifted from that position in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure). Thereby, the solid lubricant  162  can be used up to the last. Consequently, the effect that the volume of the solid lubricant  162  can be made relatively small is obtained. In the structure that the pressing mechanism  163  is provided at the main body side of the apparatus and the lubricant holding member  162 A holding the solid lubricant  162  is detachable from the pressing mechanism  163  also, the solid lubricant  162  can be used up to the last as illustrated in  FIG. 20A  and  FIG. 20B , so that the same effect can be obtained. 
     In particular, in the example illustrated in  FIG. 15A  and  FIG. 15B , the pressing mechanism  163  includes the accommodation case  165  accommodating at least a part of the lubricant holding member  162 A inside thereof, and the accommodation case  165  includes the receiving surface  165 A receiving the reaction forces applied to the movable members  163 A in the opposite direction of the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the downward direction in figure), and the surface  165 B contacting and thereby regulating the lubricant holding member  162 A from being dislocated in the direction orthogonal to the direction in which the solid lubricant  162  is pressed against the brush roller  161 , at the surface of the internal wall thereof, and the opening part  165 C, which the solid lubricant  162  held by the lubricant holding member  162 A can pass, at the part opposing the receiving surface  165 A, and the protrusion  166  is provided at the edge part of the opening part  165 C of the accommodation case  165 . Thereby, the dislocation regulation device contacting and thereby regulating the lubricant holding member  162 A from being dislocated beyond the predetermined regulation position in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure) can be realized relatively simply. At this time, as in the example illustrated in  FIG. 15A  and  FIG. 15B , by providing the contacting part  162 B of the lubricant holding member  162 A, which is brought into contact with the protrusion  166 , at the position shifted from the surface of the solid lubricant  162  on the opposite side of the surface to be rubbed by the brush roller  161  in the opposite direction of the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the downward direction in figure) by a distance equal to or greater than the thickness of the protrusion  166  provided at the edge part of the opening part  165 C of the accommodation case  165 , the protrusion  166  can be integrally formed with the accommodation case  165 , so that a lower cost can be realized. 
     Further, in this embodiment, each movable member  163 A in the pressing mechanism  163  is constructed to freely rotate around a fulcrum, and according as the solid lubricant  162  decreases by being rubbed by the brush roller  161 , the angle formed by the direction connecting the point of action where the movable member  163 A contacts the casing internal wall  164  and the fulcrum and the above-described direction in which the solid lubricant  162  is pressed against the brush roller  161  decreases, and at the same time, the angle formed by the direction connecting the point of force of the movable member  163 A where the biasing force F of the spring  163 C is received and the fulcrum and the direction of the biasing force F increases. Thereby, as described above, the effect that the change in the quantity of powdered lubricant supplied to the surface of the photoconductor  5  from the initial stage over time can be suppressed relatively small is obtained. 
     Furthermore, in this embodiment, as in the example illustrated in  FIG. 17A  and  FIG. 17B , the pressing mechanism  163  includes the guiding surfaces  464  guiding movement of the two sliding members  463 A moving in the directions in which the two sliding members  463 A come close to each other by receiving the biasing force of the spring  163 C, and the guiding surfaces  464  are slanted such that with movement of the sliding members  463 A, the sliding member  463 A are dislocated in the direction in which the solid lubricant  162  is pressed against the brush roller  161  (the upward direction in figure). With such a construction also, the effect similar to the one obtained in the structure using the above-described movable members  163 A can be obtained. Further, the similar effect can be obtained in the structure in which a compressed spring is used as the spring  163 C and the two sliding members  463 A move in the directions in which they separate from each other. 
     Further, in this embodiment, the regulation parts  164 A as the regulation members regulating the solid lubricant  162  from being dislocated in the direction of the force which the solid lubricant  162  receives by being rubbed by the brush roller  161  are provided, and the cross section of the contacting part of each movable member  163 A contacting the casing internal wall  164  at the virtual plane including the direction of the force which the solid lubricant  162  receives and the direction in which the solid lubricant  162  is pressed against the brush roller  161  is in a spire shape. Thereby, as described above, as compared with the example illustrated in  FIG. 7 , the encroaching amount of the solid lubricant  162  into the brush roller  161  can be suppressed small and thereby increasing the consumption amount of the solid lubricant  162  can be suppressed. Further, increasing the load to the motor driving the brush roller  161  can be suppressed, and the degree of bounding can be suppressed relatively small and thereby image deterioration can be suppressed. Furthermore, coming off and/or falling down of the bristles of the brush roller  161  become harder to occur, so that the life of the brush roller  161  can be made longer. 
     In particular, as illustrated in  FIG. 9 , the regulation part  164 B, which is the groove for regulating the spire-shaped part of each movable member  163 A from being dislocated in the left-to-right direction in figure by the force the solid lubricant  162  receives by being rubbed by the brush roller  161 , is provided in the receiving part of the casing internal wall  164  where the spire-shaped part of each movable member  163 A is received. Thereby, as described above, the encroaching amount of the solid lubricant  162  into the brush roller  161  is suppressed relatively small, so that it is further prevented that the consumption amount of the lubricant increases. 
     In particular, by constructing such that the cross section of the regulation part  164 B is in a V shape and the spire-shaped part of each movable member  163 A is received at the bottom part of the regulation part  164 B, which is the tip part of the V-shaped regulation part  164 B, the spire-shaped part of each movable member  163 A can be regulated from being dislocated in the left-to-right direction in figure by the force the solid lubricant  162  receives by being rubbed by the brush roller  161 , and at the same time, the advantage described next can be obtained. That is, in this embodiment, as the solid lubricant  162  decreases, each movable member  163 A is dislocated in the longitudinal direction of the solid lubricant  162  (the cross direction in figure), and in the example illustrated in  FIG. 7 , because the contact area of the movable member  163 A with the casing internal wall  164  is relatively large and thereby the friction force is increased, smooth dislocation of the movable member  163 A in the longitudinal direction of the solid lubricant  162  becomes difficult. In this case, it becomes difficult to apply an even pressing force to the solid lubricant  162 . In contrast, in the example illustrated in  FIG. 9 , the contact area of the movable member  163 A with the casing internal wall  164  is extremely small and thereby the friction force becomes relatively small, so that smooth dislocation of the movable member  163 A in the longitudinal direction of the solid lubricant  162  is enabled and consequently it becomes easier to apply the even pressing force to the solid lubricant  162 . 
     The above-described effects can be similarly obtained even when the cross section of the contacting part of each movable member  163 A is formed in an arch shape. In particular, by making the regulation part  164 B in the surface of the casing internal wall  164  as the contacted part in an arc shape also as illustrated in  FIG. 21A  and  FIG. 21B , even when the brush roller  161  is in the driven state illustrated in  FIG. 21B , the arc-shaped part of each movable member  163 A is regulated from being dislocated in the left-to-right direction in figure by the regulation part  164 B and is kept in substantially the same position as that in the stationary state illustrated in  FIG. 21A , i.e., at the center in the left-to-right direction in figure. Accordingly, as in the example illustrated in  FIG. 9 , the maximum dislocation amount of the solid lubricant  162  when the brush roller  161  has been turned into the driven state from the stationary state can be made relatively small. Further, it is preferable that a curvature radius “R” of the arc shape of the regulation part  164 B is greater than a curvature radius “r” of the arc shape of each movable member  163 A. The reason is because as in the case that the regulation part  164 B and the contacting part of each movable member  163 A are spire-shaped, while suppressing the maximum dislocation amount of the solid lubricant  162  relatively small, by making the contact area of each movable member  163 A with the regulation part  164 B relatively small and thereby the friction force relatively small, smooth dislocation of each movable member  163 A in the longitudinal direction of the solid lubricant  162  is enabled, and consequently it becomes relatively easy to apply an even pressing force to the solid lubricant  162 . Further, as compared with the case that the regulation member  164 B and the contacting part of each movable member  163 A are both spire-shaped, there is the advantage that even if a strong force is instantaneously generated and applied, the arc-shaped contact part of each movable member  163 A is hard to be deformed or broken. Consequently, it is easier to realize the even pressing force in a stable manner. 
     In this embodiment, the description has been made with respect to the case that a lubricant is supplied to the surface of the photoconductor  5 . The present invention can be applied to the case in which a lubricant is supplied to the surface of another image bearing member, such as an intermediate transfer belt, etc., or a recording member conveyance member conveying a recording member, such as a transfer sheet, etc. 
     Furthermore, in this embodiment, the description has been made with respect to the case that a lubricant is supplied to the surface of the photoconductor  5  via the brush roller  161 . However, the present invention can be applied to a structure in which a lubricant is supplied to the surface of the photoconductor  5  by causing the solid lubricant  162  to directly contact the surface of the photoconductor  5 . 
     Numerous additional modifications and variations of the present invention are possible in light of the above-teachings. It is therefore to be understood that within the scope of the claims, the present invention can be practiced otherwise than as specifically described herein.