Patent Publication Number: US-8543028-B2

Title: Maintenance system, cleaning system, and image forming apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based on and claims priority under 35 USC 119 from Japanese Patent Application No. 2010-142932 filed on Jun. 23, 2010. 
     BACKGROUND 
     Technical Field 
     The present invention relates to a maintenance system, a cleaning system, and an image forming apparatus. 
     SUMMARY 
     A maintenance system pertaining to a first aspect of the present invention includes: a maintenance device; and a control device that controls the operation of the maintenance device, wherein the control device is configured to activate the maintenance device automatically when a numerical value associated with the operation of a maintenance target device reaches a predetermined threshold value and to activate the maintenance device when it receives an instruction from a user, wherein when the control device is instructed to activate the maintenance device by an instruction from the user, the control device changes the preset threshold value such that the operation interval of the maintenance device becomes smaller. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Exemplary embodiments of the present invention will be described in detail based on the following figures, wherein: 
         FIG. 1  is a perspective view showing a cleaning system pertaining to a first exemplary embodiment of the present invention; 
         FIG. 2  is a flowchart showing a control flow of a controller used in the cleaning system pertaining to the first exemplary embodiment of the present invention; 
         FIG. 3  is a table showing threshold values of parameters used in the cleaning system pertaining to the first exemplary embodiment of the present invention; 
         FIG. 4  is a side view showing a charging member and the like used in the cleaning system pertaining to the first exemplary embodiment of the present invention; 
         FIG. 5  is a side view showing the charging member and the like used in the cleaning system pertaining to the first exemplary embodiment of the present invention; 
         FIG. 6  is a general configuration diagram showing an image forming apparatus pertaining to the first exemplary embodiment of the present invention; 
         FIG. 7  is a flowchart showing a control flow of a controller used in a cleaning system pertaining to a second exemplary embodiment of the present invention; 
         FIG. 8  is a table showing threshold values of parameters used in the cleaning system pertaining to the second exemplary embodiment of the present invention; and 
         FIG. 9  is a table showing threshold values of parameters used in a cleaning system pertaining to a third exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION 
     A cleaning system and an image forming apparatus of a first exemplary embodiment of the present invention will be described in accordance with  FIG. 1  to  FIG. 6 . 
     As shown in  FIG. 6 , an image forming apparatus  10  pertaining to the present exemplary embodiment is, proceeding from its lower side to its upper side in the vertical direction (the direction of arrow V), configured to include a housing section  12  in which sheet members P serving as a recording medium are housed, an image forming section  14  that is disposed above the housing section  12  and performs image formation on the sheet members P supplied from the housing section  12 , a document reading section  16  that is disposed above the image forming section  14  and reads reading documents G, and a controller  20  that is disposed inside the image forming section  14  and controls the working of each part of the image forming apparatus  10 . In the following description, the vertical direction (the direction of arrow V) of an apparatus body  10 A of the image forming apparatus  10  will simply be called “the vertical direction”, and the horizontal direction (the direction of arrow H shown in  FIG. 6 ) of the apparatus body  10 A of the image forming apparatus  10  will simply be called “the horizontal direction”. 
     In the housing section  12 , there are disposed a first housing unit  22 , a second housing unit  24 , and a third housing unit  26  in which the sheet members P of different sizes are housed. Moreover, in the first housing unit  22 , the second housing unit  24 , and the third housing unit  26 , there are disposed feed rolls  32  that feed the housed sheet members P to a conveyance path  28  disposed inside the image forming apparatus  10 . Additionally, on the downstream side of the feed rolls  32  in the conveyance direction of the sheet members P in the conveyance path  28  (hereinafter simply called “the conveyance direction downstream side”), there are disposed conveyance rolls  34  and conveyance rolls  36  that convey the sheet members P one at a time. Further, on the conveyance direction downstream side of the conveyance rolls  36  in the conveyance path  28 , there are disposed alignment rolls  38  that temporarily stop the sheet member P and feed the sheet member P at a determined timing to a later-described secondary transfer position. 
     Moreover, the downstream side portion of the conveyance path  28  disposed on the underside of the image forming section  14  is disposed so as to extend from the left side portion of the image forming section  14  to a paper discharge unit  15  disposed on the right side surface of the image forming section  14  when seen from the front of the image forming apparatus  10 . Further, a two-sided (duplex printing) conveyance path  29  on which the sheet member P is conveyed and inverted in order to perform image formation on both sides of the sheet member P is connected to the conveyance path  28 . 
     This two-sided conveyance path  29  has, when seen from the front of the image forming apparatus  10 , a first switching member  31  where switching between the conveyance path  28  and the two-sided conveyance path  29  is performed, an inversion portion  33  that is disposed so as to extend linearly in the vertical direction from the lower right side portion of the image forming section  14  to the right side of the housing section  12 , a conveyance portion  37  into which the trailing end of the sheet member P conveyed to the inversion portion  33  enters and on which the sheet member P is horizontally conveyed, and a second switching member  35  where switching between the inversion portion  33  and the conveyance portion  37  is performed. Additionally, conveyance rolls  42  are disposed at multiple places an interval apart from each other in the inversion portion  33 , and conveyance rolls  44  are disposed at multiple places an interval apart from each other in the conveyance portion  37 . 
     This first switching member  31  is a cross-sectionally triangular prism-shaped member whose distal end portion is moved by unillustrated driving means to either one of the conveyance path  28  or the two-sided conveyance path  29  to thereby switch the conveyance direction of the sheet member P. Similarly, the second switching member  32  is a cross-sectionally triangular prism-shaped member whose distal end portion is moved by unillustrated driving means to either one of the inversion portion  33  or the conveyance portion  37  to thereby switch the conveyance direction of the sheet member P. 
     The conveyance direction downstream side end portion of the conveyance portion  37  is connected to the conveyance path  28  by an unillustrated guide member. Further, on a wall surface on the left side of the image forming section  14 , there is disposed a foldaway manual paper supply unit  46 , and the manual paper supply unit  46  is connected in front of the alignment rolls  38  on the conveyance path  28 . 
     In the document reading section  16  disposed on the upper side of the image forming apparatus  10 , there are disposed a document conveying device  52  that automatically conveys the reading documents G one at a time, a platen glass  54  that is placed on the underside of the document conveying device  52  and on which one of the reading documents G is placed, and a document reading device  56  that reads the reading documents G conveyed by the document conveying device  52  and the reading document G placed on the platen glass  54 . 
     This document conveying device  52  has an automatic conveyance path  55  on which multiple conveyance rolls  53  are placed, and part of the automatic conveyance path  55  is placed such that the reading documents G pass over the platen glass  54 . Further, the document reading device  56  is configured to read the reading documents G conveyed by the document conveying device  52  in a state where the document reading device  56  is stationary on the left end portion of the platen glass  54  and to read the reading document G placed on the platen glass  54  while the document reading device  56  moves in the horizontal direction. 
     Moreover, in the image forming section  14  disposed on the underside of the document reading section  16 , a cylindrical image holder (image holding member)  62  on whose surface toner images are formed and held is disposed in the center of the apparatus body  10 A of the image forming apparatus  10 . The image holder  62  is rotated in the direction of arrow +R (a clockwise direction in the drawings) by unillustrated driving means and holds an electrostatic latent image formed by irradiation with light. Further, in a position above the image holder  62  and opposing the surface of the image holder  62 , there is disposed a scorotron charging member  64  that charges the surface of the image holder  62 . This charging member  64  will be described in detail later. 
     Moreover, in a position on the downstream side of the charging member  64  in the rotating direction of the image holder  62  and opposing the surface of the image holder  62 , there is disposed an exposure device  66 . The exposure device  66  is configured by a light emitting diode (LED) and irradiates (exposes) the surface of the image holder  62  charged by the charging member  64  with light on the basis of image signals corresponding to toner colors to form an electrostatic latent image. The exposure device  66  is not limited to an LED and may also, for example, use a polygon mirror to scan laser light. 
     Further, on the downstream side of the site irradiated with the exposure light of the exposure device  66  in the rotating direction of the image holder  62 , there is disposed a rotation-switching developing device  70  that develops the electrostatic latent image formed on the surface of the image holder  62  with toners of determined colors to thereby make the electrostatic latent image visible. 
     As shown in  FIG. 5 , in the developing device  70 , developing units  72 Y,  72 M,  72 C,  72 K,  72 E, and  72 F corresponding respectively to the toner colors of yellow (Y), magenta (M), cyan (C), black (K), a first special color (E), and a second special color (F) are placed so as to be juxtaposed in a circumferential direction (in this order in a counterclockwise direction). Additionally, the developing device  70  is rotated 60° at a time at a center angle by a motor (not shown) that is rotating means, whereby the developing units  72 Y,  72 M,  72 C,  72 K,  72 E, and  72 F that perform development processing are switched so as to oppose the surface of the image holder  62 . The developing units  72 Y,  72 M,  72 C,  72 K,  72 E, and  72 F have the same configuration, so here the developing unit  72 Y will be described and description in regard to the other developing units  72 M,  72 C,  72 K,  72 E, and  72 F will be omitted. 
     The developing unit  72 Y has a case member  76  serving as a body, and the inside of the case member  76  is charged with a developer (not shown) including a carrier and a toner supplied via a toner supply path (not shown) from a toner cartridge  78 Y (see  FIG. 6 ), Further, a rectangular open portion  76 A is formed in the case member  76  so as to oppose the surface of the image holder  62 , and a developing roll  74  whose surface opposes the surface of the image holder  62  is disposed in the open portion  76 A. Moreover, in a site close to the open portion  76 A inside the case member  76 , a tabular regulating member  79  for regulating the layer thickness of the developer is disposed along the lengthwise direction of the open portion  76 A. 
     The developing roll  74  is configured by a cylindrical developing sleeve  74 A, which is disposed so as to be rotatable, and a magnetic member  74 B, which has multiple magnetic poles and is fixed to the inner side of the developing sleeve  74 A. The developing sleeve  74 A rotates, whereby a magnetic brush of the developer (carrier) is formed, and the layer thickness of the developer is regulated by the regulating member  79 , whereby a developer layer is formed on the surface of the developing sleeve  74 A. Additionally, the developer layer on the surface of the developing sleeve  74 A is conveyed to a position opposing the image holder  62 , and the toner corresponding to the latent image (electrostatic latent image) formed on the surface of the image holder  62  is caused to adhere to the surface of the image holder  62 , whereby development is performed. 
     Further, inside the case member  76 , two conveyance augers  77  formed in spiral shapes are placed in parallel so as to be rotatable. These two conveyance augers  77  rotate, whereby the developer with which the inside of the case member  76  is charged is circulated and conveyed in the axial direction of the developing roll  74  (in the lengthwise direction of the developing unit  72 Y). The six developing rolls  74  disposed in each of the developing units  72 Y,  72 M,  72 C,  72 K,  72 E, and  72 F are placed in the circumferential direction such that the interval with the adjacent developing roll  74  becomes a center angle of 60° and are configured such that the next developing roll  74  opposes the surface of the image holder  62  because of the switching of the developing units  72 . 
     Moreover, on the downstream side of the developing device  70  in the rotating direction of the image holder  62  and on the underside of the image holder  62 , there is disposed an intermediate transfer belt  68  onto which the toner images formed on the surface of the image holder  62  are transferred. This intermediate transfer belt  68  is endless and is wrapped around a drive roll  61  that is driven to rotate by the controller  20 , a tension applying roll  63  for applying tension to the intermediate transfer belt  68 , multiple conveyance rolls  65  that contact the undersurface of the intermediate transfer belt  68  and passively rotate, and an auxiliary roll  69  that contacts the undersurface of the intermediate transfer belt  68  and passively rotates. Additionally, the intermediate transfer belt  68  is configured to move around in the direction of arrow −R (a counterclockwise direction in the drawings) as a result of the drive roll  61  rotating. 
     Further, on the opposite side of the image holder  62  across the intermediate transfer belt  68 , there is disposed a primary transfer roll  67  that primarily transfers the toner images formed on the surface of the image holder  62  onto the intermediate transfer belt  68 . The primary transfer roll  67  contacts the undersurface of the intermediate transfer belt  68  in a position apart from, on the downstream side in the moving direction of the intermediate transfer belt  68 , the position where the image holder  62  and the intermediate transfer belt  68  contact each other. Additionally, the primary transfer roll  67  is supplied with electricity from an unillustrated power source, whereby the primary transfer roll  67  primarily transfers the toner images on the image holder  62  onto the intermediate transfer belt  68  using the difference in electric potential with the grounded image holder  62 . 
     Moreover, on the opposite side of the auxiliary roll  69  across the intermediate transfer belt  68 , there is disposed a secondary transfer roll  71  that secondarily transfers the toner images primarily transferred onto the intermediate transfer belt  68  onto the sheet member P. The position between the secondary transfer roll  71  and the auxiliary roll  69  is configured to be a secondary transfer position where the toner images are transferred to the sheet member P. The secondary transfer roll  71  contacts the surface of the intermediate transfer roll  68 . Additionally, the secondary transfer roll  71  is grounded and secondarily transfers the toner images on the intermediate transfer belt  68  onto the sheet member P using the difference in electrical potential between the auxiliary roll  69 , to whose shaft a bias is applied from an unillustrated power source, and the grounded secondary transfer roll  71 . 
     Further, on the opposite side of the drive roll  61  across the intermediate transfer belt  68 , there is disposed a cleaning device  100  equipped with a blade  100 A that scrapes off residual toner after the secondary transfer from the intermediate transfer belt  68 . 
     Moreover, in a position opposing the tension applying roll  63  on the periphery of the intermediate transfer belt  68 , there is disposed a position detection sensor  83  that detects a predetermined reference position on the intermediate transfer belt  68  by detecting a mark (not shown) applied to the surface of the intermediate transfer belt  68  and outputs a position detection signal serving as a reference for the start timing of image formation processing. 
     Further, on the downstream side of the primary transfer roll  67  in the rotating direction of the image holder  62 , there is disposed a corotron adjusting charger  86  that charges and adjusts the charged potential of the surface of the image holder  62  to the negative side. Moreover, on the downstream side of the adjusting charger  86  in the rotating direction of the image holder  62 , there is disposed a cleaning device  73  that cleans residual toner and the like remaining on the surface of the image holder  62  without being primarily transferred onto the intermediate transfer belt  68 . 
     Further, on the downstream side of the cleaning device  73  (on the upstream side of the charging member  64 ) in the rotating direction of the image holder  62 , there is disposed an erasing device  75  that irradiates the surface of the image holder  62  with light to perform neutralization. 
     As shown in  FIG. 6 , the secondary transfer position of the toner images resulting from the secondary transfer roll  71  is set midway along the aforementioned conveyance path  28 . Additionally, on the downstream side of the secondary transfer roll  71  in the conveyance direction of the sheet member P in the conveyance path  28  (in the direction of arrow A in  FIG. 6 ), there is disposed a fixing device  80  that fixes the toner images to the sheet member P to which the toner images have been transferred by the secondary transfer roll  71 . 
     The fixing device  80  is configured by a heat roll  82 , which is placed on the toner image surface side (upper side) of the sheet member P and has a heat source that emits heat as a result of being supplied with electricity, and a pressure roll  84 , which is placed on the underside of the heat roll  82  and pressures the sheet member P towards the surface of the heat roll  82 . On the downstream side of the fixing device  80  in the conveyance direction of the sheet member P in the conveyance path  28 , there are disposed conveyance rolls  39  that convey the sheet member P towards the paper discharge unit  15  or the inversion portion  33 . 
     On the upstream side of the developing device  70  on the underside of the document reading device  56 , toner cartridges  78 Y,  78 M,  78 C,  78 K,  78 E, and  78 F that house the toners of yellow (Y), magenta (M), cyan (C), black (K), the first special color (E), and the second special color (F) are juxtaposed in the horizontal direction and disposed so as to be replaceable. The first special color E and the second special color F are configured such that they are selected or not selected from special colors (including transparent) other than yellow, magenta, cyan, and black. Additionally, the developing device  70  is configured such that, when the first special color E and the second special color F have been selected, it performs image formation in the six colors of Y, M, C, K, E, and F and such that, when the first special color E and the second special color F are not selected, it performs image formation in the four colors of Y, M, C, and K. In the present exemplary embodiment, as one example, a case where the developing device  70  performs image formation in the four colors of Y, M, C, and K and does not use the first special color E and the second special color F will be described; however, as another example, the developing device  70  may also perform image formation in five colors using the four colors of Y, M, C, and K and either the first special color E or the second special color F. 
     According to the above configuration, as shown in  FIG. 6 , when the image forming apparatus  10  is put into operation, image data of each color of yellow (Y), magenta (M), cyan (C), and black (K) are sequentially outputted from an image processing device (not shown) or the outside. At this time, as one example, the developing device  70  rotates and is held such that the developing unit  72 Y (see  FIG. 5 ) opposes the surface of the image holder  62 . Further, the blade  100 A of the cleaning device  100  and the secondary transfer roll  71  are away from the surface of the intermediate transfer belt  68  until the toner images of each color are multiply (primarily) transferred onto the intermediate transfer belt  68 . 
     Next, the surface of the image holder  62  that has been charged by the charging member  64  is exposed to light that has been emitted from the exposure device  66  according to the image data. Then, for example, an electrostatic latent image corresponding to the yellow image data is formed on the surface of the image holder  62 . Moreover, the electrostatic latent image that has been formed on the surface of the image holder  62  is developed as a yellow toner image by the developing unit  72 Y. Then, the yellow toner image on the surface of the image holder  62  is transferred onto the intermediate transfer belt  68  by the primary transfer roll  67 . 
     Next, the developing device  70  is rotated 60° in the direction of arrow +R such that the developing unit  72 M opposes the surface of the image holder  62 . Then, each step of charging, exposure, and development is performed, and the magenta toner image on the surface of the image holder  62  is transferred onto the yellow toner image on the intermediate transfer belt  68  by the primary transfer roll  67 . Similarly, the cyan (C) and black (K) toner images are sequentially multiply transferred onto the intermediate transfer belt  68 . When transfer of the toner images with respect to the intermediate transfer belt  68  ends, the blade  100 A of the cleaning device  100  and the secondary transfer roll  71  contact the surface of the intermediate transfer belt  68 . 
     Meanwhile, the sheet member P that has been fed from the housing section  12  and conveyed on the conveyance path  28  is conveyed by the alignment rolls  38  to the secondary transfer position at a timing matching the multiple transfer of each toner image to the intermediate transfer belt  68 . Then, the toner images that have been multiply transferred onto the intermediate transfer belt  68  are secondarily transferred by the secondary transfer roll  71  onto the sheet member P that has been conveyed to the secondary transfer position. Moreover, the residual toner adhering to the surface of the intermediate transfer belt  68  is scraped off of the intermediate transfer belt  68  and is recovered by the blade  100 A. 
     Next, the sheet member P to which the toner images have been transferred is conveyed in the direction of arrow A (the right direction in  FIG. 6 ) towards the fixing device  80 . Then, in the fixing device  80 , the toner images are subjected to heat and pressure by the heat roll  82  and the pressure roll  84 , whereby the toner images are fixed to the sheet member P. Moreover, the sheet member P to which the toner images have been fixed is discharged to the paper discharge unit  15  as one example. When images are to be formed on both sides of the sheet member P, image fixing is performed on the front side of the sheet member P by the fixing device  80 , and thereafter the sheet member P is sent into the inversion portion  30  along the direction of arrow −V and is sent out along the direction of arrow +V, whereby the trailing edge is interchanged with the leading edge of the sheet member P. Then, the sheet member P is conveyed in the direction of arrow B (the left direction in  FIG. 6 ) by the two-sided conveyance path  29 , is sent into the conveyance path  28 , and image formation and fixing on the back side of the sheet member P are performed in the same manner as on the front side. 
     (Configurations of Relevant Portions) 
     Next, the charging member  64  will be described. 
     As shown in  FIG. 4 , the charging member  64  is configured to include two discharge wires  102  serving as discharge electrodes, a box-like casing  105  that is equipped with the discharge wires  102  inside, and a mesh metal plate grid  104  that is disposed so as to cover an opening in the casing  105 . Moreover, as shown in  FIG. 1 , in the charging member  64 , there is disposed a cleaning system  106  that cleans the discharge wires  102  and the grid  104 . 
     Specifically, this cleaning system  106  is configured to include a cleaning device  108  serving as one example of a maintenance device and a controller  112  that controls the activation of this cleaning device  108 . Additionally, in this cleaning device  108 , there are disposed a stepping motor  114  that is rotated by the control of the controller  112 , a threaded shaft member  116  to which the motive force of this stepping motor  114  is transmitted, and a moving member  118  into which this shaft member  116  is screwed and which moves inside the casing  105  as a result of the shaft member  116  rotationally moving. 
     Further, this moving member  118  is equipped with wire cleaning portions  118 A, which sandwich and clean the discharge wires  102 , and a grid cleaning portion  118 B, which contacts and cleans the grid  104 . 
     Cumulative image density, image holder number-of-rotations, cumulative number of prints (number of sheets on which image formation has been performed), charging time, and sitting time, which serve as one example of numerical values associated with the operation of the maintenance target device, are fed into the controller  112 . 
     Additionally, as shown in  FIG. 3 , threshold values for putting the cleaning device  108  into operation are respectively preset in regard to the cumulative image density, the image holder number-of-rotations, the cumulative number of prints, the charging time, and the sitting time. In the present exemplary embodiment, in order to facilitate understanding, the threshold values that have been preset with respect to the respective parameters (hereinafter called “initial threshold values”) will be described as being 1000. Additionally, the cleaning system  106  is configured such that when any of the parameters has reached its threshold value, the controller  112  activates the cleaning device  108  so as to clean the discharge wires  102  and the grid  104 . The cleaning system  106  is also configured such that the count of that parameter is reset when the cleaning device  108  is activated. 
     Further, as shown in  FIG. 1 , in this cleaning system  106 , there is disposed an instruction button  122  that the user presses to instruct the controller  112  to activate the cleaning device  108  when, for example, the user feels that the quality of the output images has dropped when looking at the output images. That is, the cleaning system  106  is configured such that the cleaning device  108  is activated by an instruction from the user even when none of the parameters have reached their threshold values. 
     According to the above configuration, when the cleaning device  108  is activated by an instruction from the controller  112 , the stepping motor  114  rotates one way or the other, whereby the shaft member  116  rotates one way or the other such that the moving member  118  reciprocally moves inside the casing  105 . Additionally, the discharge wires  102  and the grid  104  are cleaned as a result of the moving member  118  reciprocally moving inside the casing  105 . 
     Further, the controller  112  is configured to change the threshold values of each parameter in a predetermined range (e.g., 800 to 1000) when the cleaning device  108  has been activated by an instruction from the user. 
     Moreover, the controller  112  is configured to change the threshold values of each parameter towards the initial threshold values when the cleaning device  108  has been activated consecutively multiple times (e.g., 5 times) without an instruction from the user after the preset threshold values (in the present exemplary embodiment, 1000) have been changed. 
     The configuration of the controller  112  will be described in detail together with the action. 
     (Action) 
     Next, the action of the cleaning system  106 , that is, the control by the controller  112  of the operation of the cleaning device  108  and the changing of the threshold values, will be described on the basis of the flowchart of  FIG. 2 . 
     First, in step  100 , the controller  112  recognizes a command to activate the cleaning device  108 . Then, the controller  112  moves to step  200 . 
     In step  200 , when the controller  112  judges that it is being instructed to activate the cleaning device  108  as a result of the user having pressed the instruction button  122 , it moves to step  300 , and when the controller  112  judges that it is being instructed to activate the cleaning device  108  as a result of any of the parameters having reached its threshold value, it moves to step  400 . 
     In step  300 , the controller  112  judges whether or not the instruction from the user within a predetermined amount of time exceeds a determined number of times. 
     Specifically, the controller  112  judges whether or not the number of times an instruction has been given by the user (the number of times the user has pressed the instruction button  122 ) within a predetermined amount of time (e.g., 1 hour) exceeds a determined number of times (e.g., 5 times). When the controller  112  judges that the number of times an instruction has been given by the user within the predetermined amount of time exceeds the determined number of times (is equal to or greater than 6 times), it moves to step  500 . 
     In step  500 , the controller  112  invalidates the instruction to activate the cleaning device  108  and maintains the threshold values of each parameter as is (no change). 
     On the other hand, in step  300 , when the controller  112  judges that the number of times an instruction has been given by the user within the predetermined amount of time (e.g., 1 hour) does not exceed the determined number of times (e.g., 5 times) (is equal to or less than 5 times), it moves to step  600 . 
     In step  600 , the controller  112  judges whether or not the threshold values will deviate from their predetermined ranges (e.g., 800 to 1000) if it changes the threshold values of each parameter (reduces the threshold values of each parameter by 10% as described later). When the controller  112  judges that the threshold values will deviate from their predetermined ranges, it moves to step  700 . 
     In step  700 , the controller  112  validates the instruction to activate the cleaning device  108  and activates the cleaning device  108 . Moreover, the controller  112  maintains the threshold values of each parameter as is (no change). 
     On the other hand, in step  600 , when the controller  112  judges that the threshold values will not deviate from their predetermined threshold value ranges (e.g., 800 to 1000) even if it changes the threshold values of each parameter, it moves to step  800 . 
     When the controller  112  judges that the threshold values will not deviate from their predetermined ranges if it changes the threshold values by 10%, it moves to step  800 ; however, the controller  112  may also be configured such that when the threshold values will fall below their lower limit values (800) if it changes the threshold values by 10%, it changes the threshold values by 7%, for example, so that the threshold values become the lower limit values (800) and then moves to step  800 . 
     In step  800 , the controller  112  validates the instruction to activate the cleaning device  108  and activates the cleaning device  108 . Moreover, the controller  112  changes the threshold values of each parameter across the board. Specifically, as shown in  FIG. 3 , the controller  112  reduces the threshold values of each parameter by 10%. 
     That is, it is presumed that the user has pressed the instruction button  122  to activate the cleaning device  108  because the threshold values are large (long) as compared to threshold values for activation intervals meeting the demand of the user with respect to image quality. That being the case, considering the current usage and the satisfaction of the user, it is necessary to reduce (shorten) the threshold values because the threshold values are large (long). Thus, the controller  112  reduces the threshold values of each parameter by 10%. 
     In this manner, the controller  112  reduces the threshold values and returns. After step  500  and after step  700  also, the controller  112  similarly returns. 
     In contrast, as shown in  FIG. 2 , in step  200 , when the controller  112  has been instructed to activate the cleaning device  108  as a result of any of the parameters having reached its threshold value and has moved to step  400 , then in step  400 , the controller  112  judges whether or not the threshold values are being changed from the initial threshold values. When the controller  112  judges that the initial threshold values are not being changed, it moves to step  900 . 
     In step  900 , the controller  112  validates the instruction to activate the cleaning device  108  and activates the cleaning device  108 . Moreover, the controller  112  maintains the threshold values of each parameter as is (no change). 
     On the other hand, in step  400 , when the controller  112  judges that the threshold values are being changed from the initial threshold values, it moves to step  1000 . 
     In step  1000 , the controller  112  judges whether or not the cleaning device  108  is being activated, without an instruction from the user, consecutively a predetermined number of times (e.g., 3 times) in the past. When the controller  112  judges that the cleaning device  108  is not being activated consecutively the predetermined number of times (equal to or less than 2 times), it moves to step  1100 . 
     In step  1100 , the controller  112  validates the instruction to activate the cleaning device  108  and activates the cleaning device  108 . Moreover, the controller  112  maintains the threshold values of each parameter as is (no change). 
     On the other hand, in step  1000 , when the controller  112  judges that the cleaning device  108  is being activated consecutively the predetermined number of times (equal to or greater than 3 times), it moves to step  1200 . 
     In step  1200 , the controller  112  validates the instruction to activate the cleaning device  108  and activates the cleaning device  108 . Moreover, the controller  112  changes the changed threshold values towards the initial threshold values. 
     In this manner, the controller  112  changes the changed threshold values towards the initial threshold values and returns. After step  900  and after step  1100  also, the controller  112  similarly returns. 
     As described above, the threshold values for activating the cleaning device  108  are changed depending on the usage. Additionally, because the threshold values are changed in this manner, the number of times the cleaning device  108  is activated can be changed depending on the situation of forced activation in a configuration having forced activation and automatic activation. 
     Further, because the controller  112  changes the multiple threshold values across the board in step  800 , the threshold values are changed by a simple method. 
     Further, when the number of times an instruction has been given by the user within the predetermined amount of time exceeds the determined number of times, the controller  112  invalidates the instruction to activate the cleaning device  108  in step  500 . In this manner, the controller  112  does not activate the cleaning device  108  when it judges that activation is unnecessary. 
     Further, in changing the threshold values, when the threshold values will deviate from their predetermined threshold value ranges, the controller  112  maintains the threshold values of each parameter as is in step  700  (no change). In this manner, excessive activation is controlled by changing the threshold values within their predetermined threshold value ranges. 
     Further, when the cleaning device  108  has been activated, without an instruction from the user, consecutively a predetermined number of times in the past, then in step  1200 , the controller  112  changes the changed threshold values towards the initial threshold values. That is, it is presumed that the threshold values are large (long) as compared to threshold values for activation intervals meeting the demand of the user with respect to image quality, so by returning the threshold values to the initial threshold values, the cleaning device is efficiently activated. 
     Further, because the cleaning device is efficiently activated depending on the usage, the quality of the output images improves. 
     Next, a cleaning system and an image forming apparatus of a second exemplary embodiment of the present invention will be described in accordance with  FIG. 7  and  FIG. 8 . Members that are the same as those in the first exemplary embodiment will be denoted by the same reference numerals and description thereof will be omitted. 
     As shown in  FIG. 7 , in step  200 , when the controller  112  judges that it is being instructed to activate the cleaning device  108  as a result of the user having pressed the instruction button  122 , it moves to step  310 . 
     In step  310 , the controller  112  judges whether the instruction to activate the cleaning device  108  from the user again is consecutive without the cleaning device  108  being automatically activated after the user has activated the cleaning device  108  a previous time and judges whether or not a predetermined amount of time (e.g., 1 hour) has elapsed since the instruction from the user the previous time. 
     That is, the controller  112  judges whether or not the amount of time between when the user pressed the instruction button  122  the previous time and when the user pressed the instruction button  122  this time exceeds the predetermined amount of time (e.g., 1 hour). When the controller  112  judges that the determined amount of time has not elapsed, it moves to step  500  and invalidates the instruction to activate the cleaning device  108 . Further, when the controller  112  judges that the determined amount of time has elapsed, it moves to step  600 . 
     In this manner, by invalidating the instruction to activate the cleaning device  108  when the controller  112  judges that the determined amount of time has not elapsed, activation of the cleaning device  108  that has been judged unnecessary is invalidated, and the cleaning device  108  is efficiently activated. 
     Further, as shown in  FIG. 8 , in step  800 , when the controller  112  changes the threshold values of each parameter, it does not change the threshold values across the board but rather individually changes, on the basis of the activation history of the cleaning device  108 , the threshold values disposed for each of the multiple parameters. 
     For example, in the present exemplary embodiment, the threshold value set for the cumulative image density has been reached 5 times in the past, and the threshold value set for the image holder number-of-rotations has been reached 2 times in the past. Moreover, the threshold values set for the cumulative number of prints, the charging time, and the sitting time have each been reached 1 time in the past. 
     Thus, the controller  112  increases the rate of change of the threshold values that have been reached many times. For example, the total number of times the threshold values have been reached is 10 times, and the threshold value set for the cumulative image density accounts for 5 of those times. When the controller  112  is configured to change the threshold values by 10%, the controller  112  changes a quantity corresponding to 5/10 of 10% in regard to the threshold value set for the cumulative image density, changes a quantity corresponding to 2/10 of 10% in regard to the threshold value set for the image holder number-of-rotations, and changes quantities corresponding to 1/10 of 10% in regard to the threshold values set for the cumulative number of prints, the charging time, and the sitting time. 
     Thus, the threshold value set for the cumulative image density becomes 950, the threshold value set for the image holder number-of-rotations becomes 980, and the threshold values set for the cumulative number of prints, the charging time, and the sitting time become 990. 
     In this manner, by individually changing, on the basis of the activation history of the cleaning device  108 , the threshold values disposed for each of the multiple parameters, the threshold values are finely changed depending on the usage. 
     Next, a cleaning system and an image forming apparatus of a third exemplary embodiment of the present invention will be described in accordance with  FIG. 9 . Members that are the same as those in the first exemplary embodiment will be denoted by the same reference numerals and description thereof will be omitted. 
     As shown in  FIG. 9 , in step  800 , when the controller  112  changes the threshold values of each parameter, it does not change the threshold values across the board but rather individually changes, on the basis of the activation history of the cleaning device  108 , the threshold values disposed for each of the multiple parameters. 
     For example, in the present exemplary embodiment, the threshold value set for the cumulative image density has been reached 5 times in the past, and the threshold value set for the image holder number-of-rotations has been reached 2 times in the past. Moreover, the threshold values set for the cumulative number of prints, the charging time, and the sitting time have each been reached 1 time in the past. 
     Thus, the controller  112  changes the top two threshold values that have been reached many times. Specifically, the controller  112  reduces by 10% across the board the threshold value set for the cumulative image density and the threshold value set for the image holder number-of-rotations across the board, so that these two threshold values become 900. 
     In this manner, by individually changing, on the basis of the activation history of the cleaning device  108 , the threshold values disposed for each of the multiple parameters, the threshold values are finely changed depending on the usage. 
     The present invention has been described in detail in regard to particular exemplary embodiments, but the present invention is not intended to be limited to these exemplary embodiments, and it will be apparent to those skilled in the art that various other embodiments may be made within the scope of the present invention. For example, in the exemplary embodiments described above, although it is not particularly limited, in step  1200 , when the controller  112  changes the changed threshold values towards the initial threshold values, the controller  112  may also change the changed threshold values towards the initial threshold values in stages or may also change the changed threshold values to the initial threshold in one go. 
     Further, in the exemplary embodiments described above, maintenance of the image forming apparatus is performed as a result of the controller  112  activating the cleaning device  108  to clean the charging member  64 , but the maintenance of the image forming apparatus is not particularly limited to cleaning a charging member and can be used in various cleaning devices and the like. For example, maintenance of the image forming apparatus may also be performed by cleaning (blowing out) old developer retained inside the developing device. 
     The foregoing description of the exemplary embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The exemplary embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the following claims and their equivalents.