Patent Publication Number: US-10324406-B2

Title: Apparatus and system for forming image

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a National Phase application of International Application No. PCT/JP2016/000310, filed Jan. 21, 2016, which claims the benefit of Japanese Patent Application No. 2015-032064, filed Feb. 20, 2015. The disclosures of the above-named applications and patent are hereby incorporated by reference herein in their entirety. 
     TECHNICAL FIELD 
     The present invention relates to an apparatus for evaluating the state of a member for use in forming an image. 
     BACKGROUND ART 
     Electrophotographic and ink-jet image forming apparatuses (printers, copiers, facsimile machines, etc.) are generally configured to allow consumable items to be replaced. When an image forming apparatus detects the lives of these replaceable consumable items (also referred to as replaceable items) and determine that the lives have expired and these items should be replaced, the image forming apparatus displays a message that prompts a user or a serviceperson to replace the replaceable items. 
     For example, in electrophotographic image forming apparatuses, toner cartridges and fusers are replaceable items. The image forming apparatuses detect the lives of such replaceable items. An example of a method for detecting the amount of toner in a toner cartridge is disclosed in PTL 1. This is a method for detecting a change in the amount of toner in the cartridge by detecting electrostatic capacitance. PTL 2 discloses a method for detecting the toner level using an LED and a photo-detector. An example of a method for indirectly estimating the amount of toner is disclosed in PTL 3. This is a method for estimating toner consumption on the basis of image information (pixel count). 
     However, the replaceable items in the image forming apparatuses vary in dimensional tolerance among replaceable items and in operating environment of the user. This can cause a difference in the degree of degradation among replaceable items, making it difficult to accurately detect the expiration of the lives of the individual replaceable items. If a uniform threshold value for determining the lives is set, the user sometimes cannot use up the replaceable items to the proper expiration of their lives. Although the above methods allow accurate detection of the amount of toner, the methods require a dedicated sensor, leading to a complicated configuration and an increase in cost. 
     CITATION LIST 
     Patent Literature 
     PTL 1: Japanese Patent Laid-Open No. 5-6092 
     PTL 2: Japanese Patent Laid-Open No. 7-140776 
     PTL 3: Japanese Patent Laid-Open No. 2001-318566 
     SUMMARY OF INVENTION 
     The present invention provides an apparatus and a system capable of accurately detecting the life of replaceable items with a simple configuration. 
     An image forming apparatus according an aspect of the present invention includes a member for use in forming an image on a recording material, an acquiring unit configured to acquire first image information on the image formed on the recording material, a scanning unit configured to scan the image formed on the recording material to acquire second image information; and a control unit configured to determine a state of the member, wherein in a case that a usage amount of the member is larger or equal to a threshold, the control unit compares the first image information with the second image information, and determines the state of the member based on a comparison result. 
     An image forming system according to another aspect of the present invention includes an image forming apparatus, an external device communicating with the image forming apparatus, wherein the image forming apparatus comprises a member for use in forming an image on a recording material, wherein the external device comprises a storage unit configured to store first image information on the image formed on the recording material; and a control unit configured to determine a state of the member, wherein in a case that a usage amount of the member is larger or equal to a threshold, the control unit compares the first image information with the second image information, and determines the state of the member based on a comparison result. 
     Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of an image forming apparatus according to a first embodiment of the present invention. 
         FIG. 2  is a block diagram of a system configuration of the image forming apparatus according to the first embodiment. 
         FIG. 3  is a flowchart for determining the life of process cartridges of the first embodiment. 
         FIG. 4  is a diagram illustrating a network configuration according to a second embodiment. 
         FIG. 5  is a schematic diagram of an image forming apparatus according to the second embodiment of the present invention. 
         FIG. 6A  is a block diagram of the system configuration of the image forming apparatus of the second embodiment. 
         FIG. 6B  is a block diagram of the system configuration of a server according to the second embodiment. 
         FIG. 7  is a diagram illustrating entries of additional print information according to the second embodiment. 
         FIG. 8  is a conceptual diagram of the sequence of determining the lives of replaceable items according to the second embodiment. 
         FIG. 9  is a flowchart for the operation of a controller for printing an image according to the second embodiment. 
         FIG. 10  is a flowchart for the operation of the controller for scanning an image according to the second embodiment. 
         FIG. 11  is a flowchart for the operation of the server for determining the expiration of the lives of the cartridges according to the second embodiment. 
         FIG. 12  is a flowchart for the operation of the server for determining the expiration of the lives of the cartridges when instructed to register image data according to a third embodiment of the present invention. 
         FIG. 13  is a flowchart for the operation of the server for determining the expiration of the lives of the cartridges according to the third embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Embodiments of the present invention will be described hereinbelow with reference to the drawings. It is to be understood that the following embodiments do not limit the invention according the scope of the claims and that not all of combinations of the features described in the embodiments are essential for the solution of the invention. 
     First Embodiment 
     In this embodiment, a method for determining whether replaceable items used in an image forming apparatus have come to the end of the lives on the basis of image data printed on a recording material (hereinafter referred to as “paper”) and scanned image data acquired by scanning printed paper will be described. 
     Referring first to  FIG. 1 , the general arrangement, in outline, of an electrophotographic color-image forming apparatus for use in describing this embodiment will be described. The image forming apparatus according to this embodiment is a laser printer  100  using an electrophotographic image forming process. The color-image forming apparatus shown in  FIG. 1  includes process stations (process cartridges)  5 Y,  5 M,  5 C, and  5 K detachable from the printer  100 . The four cartridges  5 Y,  5 M,  5 C, and  5 K have the same structure but differ in forming images with toners (developers) of different colors, that is, yellow (Y), magenta (M), cyan (C), and black (K). The signs Y, M, C, and K will be omitted except when a specific cartridge is described. Each of the cartridges  5  includes a toner container  23 , a photosensitive drum  1  (a photoconductor), a charging roller  2 , a developing roller  3 , a cleaning blade  4  (a photoconductor cleaning unit), and a waste-toner container  24 . An exposing unit  7  disposed below each cartridge  5  exposes the photosensitive drum  1  to light in response to an image signal according to image data. 
     The photosensitive drum  1  is uniformly charged to a predetermined polarity and a predetermined potential by the charging roller  2  during rotation. The photosensitive drum  1  is then exposed to light by the exposing unit  7  to form an electrostatic latent image corresponding to one of first to fourth color component images (yellow, magenta, cyan, and black component images) of a target color image. The charging roller  2  rotates together with the rotation of the photosensitive drum  1 . The electrostatic latent image formed on the photosensitive drum  1  is developed by the developing roller  3  of corresponding one of the first to fourth cartridges Y, M, C, and K. A corresponding color toner is attached to the electrostatic latent image on the photosensitive drum  1  via the developing roller  3  to develop a toner image. The toner in the toner containers  23  is a negatively charged non-magnetic single-component toner, and the electrostatic latent images are developed using a non-magnetic single-component contact developing method. A voltage is applied to the developing roller  3  from a power source (not shown) to perform development. 
     An intermediate transfer belt unit includes an intermediate transfer belt  8 , a driving roller  9 , and a secondary-transfer facing roller  10 . A primary transfer roller  6  is disposed inside the intermediate transfer belt  8  in such a manner as to be opposed to each photosensitive drum  1 . A positive-polarity primary transfer bias is applied to the primary transfer roller  6  from a primary transfer bias source (not shown). The intermediate transfer belt  8  is run as the driving roller  9  is rotated by a motor (not shown), and the secondary-transfer facing roller  10  is also rotated therewith. Each photosensitive drum  1  rotates in the direction of arrow, the intermediate transfer belt  8  rotates in the direction of arrow A, and a positive-polarity primary transfer bias is applied to the primary transfer roller  6 . This causes toner images on the photosensitive drums  1  to be primarily transferred onto the intermediate transfer belt  8  in order from a toner image on the photosensitive drum  1 Y. The toner image in which four colors overlap with one another is conveyed to a secondary transfer roller  11 . The cleaning blade  4  on the photosensitive drum  1  is pressure-contact with the photosensitive drum  1  to remove toner that has not been transferred to the intermediate transfer belt  8  and remains on the surface of the photosensitive drum  1  and other residues on the photosensitive drum. 
     The feeding conveying unit  12  includes a paper cassette  13  for accommodating paper P, a feed roller  14  for feeding the paper P from the paper cassette  13 , and a conveying roller pair  15  for conveying the fed paper P. The paper P conveyed from the feeding conveying unit  12  is conveyed to the secondary transfer roller  11  by a resist roller pair  16 . In transfer of the image from the intermediate transfer belt  8  onto the paper P, the four-color toner image on the intermediate transfer belt  8  is secondarily transferred to the conveyed paper P by applying a positive-polarity bias to the secondary transfer roller  11  (hereinafter referred to as “secondary transfer”). 
     The paper P to which the toner image is transferred is conveyed to a fuser  17 . The fuser  17  is a film-heating fuser including a fusing roller  18 , in which a fusing heater  30  and a temperature sensor  31  for measuring the temperature of the fusing heater  30  are disposed, and a pressure roller  19  for coming into contact with the fusing roller  18 . The toner image is fixed by heating and pressing the paper P, and the paper P is discharged out of the printer  100  as an image-formed material (such as printed paper). The printer  100  is capable of printing on two sides of the paper P. The printer  100  further includes an image scanning unit  2050  on the conveying path for two-sided printing. The image scanning unit  2050  provides a scanning function for obtaining a paper P scan image. 
     For two-sided printing of the paper P, after the rear end of the paper P that has passed through the fuser  17  passes through a two-sided flapper  50 , the position of the two-sided flapper  50  is switched to the two-sided conveying path. The rotating direction of a discharge roller pair  20  is switched to the two-sided conveying path by a reversing clutch  2024  (not shown in  FIG. 1 ) that determines the rotating direction of the discharge roller pair  20 . This causes the conveying direction of the paper P to be reversed to the two-sided conveying path. On the two-sided conveying path, the paper P is conveyed to the resist roller pair  16  by a two-sided conveying roller pair  51  and a main-body merging roller pair  53 . From the resist roller pair  16  onward, the paper P is processed similarly to the front surface and is discharged out of the printer  100  through the fuser  17 . 
     To scan the surface of the paper P with the image scanning unit  2050 , the paper P is conveyed to the two-sided conveying path as for the above-described two-sided printing, and at the timing when the paper P passes through the two-sided conveying roller pair  51 , the image scanning unit  2050  starts to scan the surface of the paper P. The image scanning unit  2050  includes a light-emitting device and a contact image sensor (CIS) (not shown). The image scanning unit  2050  photoelectrically scans the image on the paper P being conveyed into time-series digital pixel signals and accumulates the signals as scanned image data in a memory in the image scanning unit  2050 . The paper P after the image scanning is completed passes through the paper conveying path and is discharged out of the printer  100 . 
     Control Block Diagram 
       FIG. 2  is a control block diagram of the printer  100  of this embodiment. The printer  100  includes a controller  1000  and an engine  2000 . The controller  1000  is a controller for inputting and outputting image information and device information by connecting to the engine  2000 , which is an image output device, and to a LAN  1013 . A controller control unit  1010  is a CPU that controls the whole image forming system and includes a RAM (not shown) serving as a work memory and a ROM (not shown) in which a boot program is stored. A hard disk drive (HDD)  1020  stores system software and image data. A pixel measuring unit  1040 , an image-comparing life-determining unit  1041 , and a life-expiration determining unit  1042  are functions of the software stored in the HDD  1020  that the controller control unit  1010  executes. An operation unit I/F  1011  is an interface to an operation unit  1014  including a touch panel and outputs image data to be displayed on the operation unit  1014  to the operation unit  1014 . The operation unit I/F  1011  also has a function of communicating information input by the user of this system from the operation unit  1014  to the controller control unit  1010 . A network I/F  1012  connects to the LAN  1013  to input and output (communicate) information. A raster image processor  1030  develops a PDL code into a bitmap image. An engine-image processing unit  1034  converts the bitmap image developed by the raster image processor  1030  to image data to be transmitted to the engine  2000  through correction and conversion of the resolution of the bitmap image. A scanned-image processing unit  1033  corrects, processes, and edits the input image data obtained by scanning with the image scanning unit  2050 . 
     The controller control unit  1010  and an engine control unit  2010  are connected together via a video I/F  1100 . The controller control unit  1010  gives an operating instruction and transmits image data to the engine control unit  2010  via the video l/F  1100 . The engine  2000  is an image output device. The engine control unit  2010  operates the individual units in the engine  2000  via the video I/F  1100  to perform printing on the paper P according to an instruction from the controller  1000 . The engine control unit  2010  is a CPU that controls the whole engine  2000  and includes a RAM (not shown) and a ROM (not shown) in which programs for controlling the engine  2000  are stored. A toner-level estimating unit  2040  is a function of a program stored in the ROM that the engine control unit  2010  executes. 
     The engine control unit  2010  includes a motor (not shown) for driving a fusing unit  2020  for energizing the fuser  17  and the photosensitive drums  1 , the intermediate transfer belt  8 , the pressure roller  19 , and other components of the printer  100 . The engine control unit  2010  is connected to a motor driving unit  2021  for driving the motor, an exposure control unit  2022  for controlling the exposing units  7 , the two-sided flapper  50  for switching the conveying path of the paper P during two-sided printing, and the reversing clutch  2024  for switching the rotating direction of the discharge roller pair  20 . A toner image is thus printed on the paper P by electrophotographic process on the basis of image data transmitted from the controller  1000  via the video I/F  1100 . 
     The engine control unit  2010  is also connected to the image scanning unit  2050 . When an image on the front of the paper P is to be scanned, the engine control unit  2010  gives a scanning instruction to the image scanning unit  2050  before the paper P reaches the image scanning unit  2050 . After the paper P passes through the image scanning unit  2050 , the engine control unit  2010  notifies the controller control unit  1010  of completion of image scanning. The controller control unit  1010  acquires scanned image data accumulated in the image scanning unit  2050  via the video I/F  1100 . 
     The functions of the controller  1000  and the engine  2000  may be implemented by the individual CPUs executing the individual control programs, or alternatively, part or all of the functions may be implemented by application specific integrated circuits (ASICs). 
     Detection of Toner Level and Determination of Image 
     When the amount of toner in the toner container  23  decreases, the amount of toner supplied to the latent image decreases, and the toner image cannot have necessary darkness. The toner is stirred in the process cartridges  5  and is subjected to friction due to stirring members in the cartridges  5 . The friction causes an external additive on the surface of the toner to fall off, thereby gradually reducing the charging characteristics. The reduction in charging characteristics decreases the darkness of the toner image. Because of this, after the toner has reached the end of the life, the toner image cannot have desired darkness. When the toner degrades and cannot have desired image darkness, the printer  100  needs to detect that the life of the toner has expired and to notify the user of the expiration to prompt the user to replace the process cartridge  5 . 
     In this embodiment, measurement of the amount of remaining toner uses a method of estimation based on the number of pixels. The pixel measuring unit  1040  in the controller control unit  1010  measures the toner level by counting the numbers of pixels of YMCK colors from a bitmap image developed from a PDL code by the raster image processor  1030 . When the controller control unit  1010  gives a print instruction to the engine control unit  2010 , the controller control unit  1010  notifies the number of pixels of an image to be printed to the engine control unit  2010 . The toner-level estimating unit  2040  in the engine control unit  2010  adds up the number of pixels notified. The toner-level estimating unit  2040  has a threshold value of the number of pixels for use in determining whether the toner in the process cartridges  5  has come to the end of life according to the amount of toner. The toner-level estimating unit  2040  estimates the toner level from the total pixel count and the threshold value of the pixel count and notifies the toner level to the controller control unit  2010 . The controller control unit  1010  displays a message to prompt the user to replace the process cartridge  5  on the operation unit  1014  according to the estimated toner level received from the engine control unit  2010 . 
     However, depending on the kind of image to be printed or the environment around the printer  100 , the pixel count does not always correspond to the amount of toner actually consumed level. This causes errors to be cumulated as the number of sheets printed increases, making it difficult to accurately estimate the life. In this embodiment, print image data, which is first image information to be printed on the paper P, is compared with scanned image data, which is scanned second image information, using the image scanning unit  2050  of the image forming apparatus to determine whether the process cartridge  5  has expired. When the amount or the quality of toner decreases, the toner becomes unable to have desired darkness (becomes lighter than desired darkness), as described above. This embodiment compares the scanned image data with the print image data by using this poor image characteristics to determine whether the toner on the printed paper P has desired darkness, thereby determining whether the life of the toner has expired. However, the darkness of the toner decreases also when the amount of laser from the exposing unit  7  decreases. Accordingly, if something unusual occurs in the exposing unit  7 , using only information on the toner darkness will lead to misdetermination on the life of the cartridge  5 . This embodiment allows accurate determination on the lives of the cartridges  5  by combining the life determination by comparing a scanned image and a printed image with the life determination using a pixel count. 
     Flowcharts 1 
       FIG. 3  is a flowchart for the operation of the controller control unit  1010  for determining whether the life of the process cartridge  5  has expired from a scanned image acquired by scanning an image printed on the paper P by using the image scanning unit  2050 . The steps of starting and terminating the control are the start and the end of the program and descriptions thereof will be omitted (the same applies to all the following flowcharts). 
     A job described in a page description language (PDL) is transmitted to the printer  100  via the LAN  1013 , and the controller control unit  1010  starts to execute the job (S 100 ). The controller control unit  1010  converts the transmitted PDL to a bitmap image with the raster image processor  1030  (S 101 ). The controller control unit  1010  stores the generated bitmap image in the HDD  1020  (S 102 ). The bitmap image is converted to image data to be transmitted to the engine  2000  with the engine-image processing unit  1034  (S 103 ). The controller control unit  1010  then determines whether the estimated toner levels of the individual process cartridges  5 , which have been received from the engine control unit  2010  at the job starting point, are lower than a predetermined threshold value (S 104 ). The threshold value used at S 104  is a toner level that the toner-level estimating unit  2040  has notified at the point when an actual toner level has come to the end of life on the assumption that an error of a toner level estimated using a pixel count from the actual toner level, which is acquired by experiment, has occurred at all pages. 
     If the estimated toner level is higher than or equal to the threshold value, the controller control unit  1010  issues an instruction to start printing to the engine  2000  as usual to execute printing (S 120 ). If the estimated toner level is lower than the threshold value, the controller control unit  1010  issues an instruction to print an image on the paper P and to scan the printed image using the image scanning unit  2050  to the engine  2000  (S 105 ). The engine  2000  prints the image on the paper P on the basis of the image data from the controller  1000  and scans the image printed on the paper P with the image scanning unit  2050  while conveying the printed paper P to the two-sided conveying path. When the controller  1000  is notified of completion of image scanning by the engine  2000  (S 106 ), the controller  1000  acquires a bitmap image of the scanned image from the engine  2000  (S 107 ). The controller  1000  compares the printed bitmap image stored in the HDD  1020  with the scanned bitmap image using the image-comparing life-determining unit  1041  (S 108 ). The image-comparing life-determining unit  1041  converts the printed bitmap image and the scanned bitmap image from RGB data to CMYK data. The image-comparing life-determining unit  1041  calculates the average darkness of the individual CMYK colors for each of the CMYK data on the printed image and the CMYK data on the scanned image. For a color whose estimated toner level is determined at S 104  to be lower than the threshold value, the image-comparing life-determining unit  1041  determines whether the average darkness of the scanned image is smaller than (lighter than) the average darkness of the printed image by a predetermined threshold value or more (S 109 ). If it is determined that the scanned image is lighter than the printed image, the life-expiration determining unit  1042  determines that the toner has come to the end of the life because the toner may be degraded, so that sufficient darkness of the image cannot be ensured, and the controller control unit  1010  prompts the user to replace the process cartridge  5  with the operation unit  1014  (S 110 ). The threshold value used at S 109  is set to a value that will not lead to misdetermination on life during image analysis on the basis of data on variation in darkness when the engine  2000  prints an image on the paper P. 
     This is a method for determining whether the lives of the cartridges  5  of an image forming apparatus including an image scanner have expired from the analysis of a printed image and a scanned image. 
     Thus, the embodiment of the present invention allows the lives of replaceable items of an image forming apparatus including an image scanning unit to be determined from the analysis of a printed image and a scanned image. Since the expiration of the lives of replaceable items is determined from images, the expiration of the lives can be accurately detected without adding hardware for detecting the expiration of the lives. 
     This method allows higher accuracy detection of expiration of lives than that using a method of indirect detection using an estimated toner pixel count or a rotating time. Furthermore, this embodiment uses a combination of life determination based on image analysis and life determination based on a pixel count, thereby preventing misdetermination that replaceable items have expired because of a change in image characteristics due to a defect of the image forming apparatus. Furthermore, the image analysis is executed only under a situation in which cartridges seem to have come close to the end of lives from the result of determination based on the pixel count. This can reduce the number of times of analysis if determination of life based on image analysis takes much time. If a defect can be accurately specified only from image analysis, there is no need to use a pixel count. In this case, the embodiment can also be applied to defects in a component if not only a decrease in durability but also an unexpected problem exert an influence on the images, for example, low printing accuracy due to a problem of a paper conveying component caused by an impact. 
     In this embodiment, a method for determining the time to replace the cartridges  5  using image analysis focusing on the darkness of images has been described. This embodiment is applicable to replaceable items that decrease in durability, such as the photoconductor  1 , the intermediate transfer belt (intermediate transfer member)  8 , the fusing roller  18  and the pressure roller  19  of the fuser  17 , and the feed roller  14  of the feeding conveying unit  12 . For this purpose, an algorithm for analyzing signs in images peculiar to the individual replaceable items caused according to degradation is prepared. For the above replaceable items, for example, individual driving times are measured and accumulated, and control (for determining whether the accumulated driving time is larger than or equal to a threshold value) is performed on the basis of the measured driving time. 
     In this embodiment, the image forming apparatus is a color laser printer. This method can also be applied to printers with other configurations, such as a monochrome laser printer and an ink-jet printer. While in this embodiment the image scanning unit is disposed on the two-sided conveying path, any image scanning units capable of scanning printed paper, for example, a scanning unit separately disposed above an image forming apparatus, may be used. 
     Second Embodiment 
     This embodiment assumes a situation in which a copier including an image forming apparatus and a scanning unit is connected to a network. For example, this embodiment is characterized in that, when a user scans paper P that is printed with one of copiers connected to a network, the lives of replaceable items of the copier that prints the paper P are determined. In the drawings of this embodiment, the same functions as those of the first embodiment are given the same reference signs and descriptions thereof will be omitted. 
       FIG. 4  is a diagram illustrating the network configuration of this embodiment. This network configuration includes a host PC  160 , a print server  161 , a life-expiration determining server  162 , and one or more copiers  150  connected to the LAN  1013 . 
     The host computer  160  has functions of editing an application file by a user and transmitting jobs to the print server  161 . The main roles of the print server  161  are transmission and reception of information to and from devices outside a printing unit and management control of the printing unit. Jobs input from the host computer  160  are centrally managed by the print server  161 , so that the statuses of all the copiers  150  connected to the LAN  1013  and all the jobs can be monitored and controlled (e.g., job pause). The copiers  150  have functions of printing jobs transmitted from the print server  161 , scanning and copying documents of the user. The life-expiration determining server  162  is a server for determining the expiration of the lives of replaceable items in the copier  150 . 
       FIG. 5  is a diagram illustrating the internal configuration, in outline, of the copiers  150 . This is the configuration of a typical copier in which a document scanning unit  200  applies light onto a document placed on a platen to scan the document. Descriptions of the same functions as those of the image forming apparatus of the first embodiment will be omitted. The document scanning unit  200  includes a platen glass  201  serving as a document table, a scanner  202 , a document lighting lamp  203 , and scanning mirrors  204 ,  205 , and  206 , a lens  207 , and an image sensor  208  and scans a document conveyed by an automatic document feeder (DF)  220 . In the document scanning unit  200 , the scanner  202  reciprocates in predetermined directions with a motor (not shown), and light reflected by the document passes through the lens  207  via the scanning mirrors  204 ,  205 , and  206  and forms an image on a CCD sensor in the image sensor  208 . The image sensor  208  includes a memory, in which RGB data based on signals of images formed on the CCD sensor is accumulated. 
       FIG. 6A  is a block diagram of the image forming apparatus of this embodiment. A barcode adding unit  1200 , an image registering unit  1201 , a barcode analyzing unit  1202 , and an image-determination requesting unit  1203  are functions of software that a controller operation unit  1010  stored in a HDD  1020  executes. The barcode adding unit  1200  is a function of adding additional print information to a bitmap image developed from a PDL code by a raster image processor  1030 . Additional print information in this embodiment is illustrated in  FIG. 7 . Print date  5000  is time at which printing is performed by the copier  150 . Printer SN  5001  is a serial number assigned to the copier  150  as distinguished from the other copiers  150 . Page count  5002  is counted in the copier  150 . Image analysis request  5003  is information indicating whether to determine the expiration of the life using an image analysis performed by the copier  150 . CRG SN  5004  indicates the serial numbers of the individual process cartridges  5  used for printing by the copier  150 . In this embodiment, the additional print information is embedded in the margin of a bitmap image to be printed as a two-dimensional code, for example, a QR code (a registered trademark, the rest is omitted). The additional print information may be another barcode other than the QR code or may be embedded using an electronic watermark technique. 
     The image registering unit  1201  is a function of transmitting print image data (a bitmap image) to which the additional print information is added and the additional print information to the life-expiration determining server  162  to register therein in association with each other. The barcode analyzing unit  1202  is a function of searching scanned image data (a bitmap image) scanned by the document scanning unit  200  for a QR code and analyzing the QR code, if found, to acquire the additional print information. The image-determination requesting unit  1203  is a function of transmitting the scanned image data scanned by the document scanning unit  200  and the additional print information acquired by the barcode analyzing unit  1202  to the life-expiration determining server  162  to request to determine the expiration of life on the basis of the images. 
       FIG. 6B  is a block diagram of the life-expiration determining server  162 . The life-expiration determining server  162  is connected to the LAN  1013  to register an image printed by the copier  150  and determine the lives of replaceable items on the basis of the scanned image data acquired by the copier  150 . 
     A server control unit  2510  is a CPU that controls the whole life-expiration determining server  162  and includes a RAM (not shown) serving as a work memory and a ROM (not shown) in which a boot program is stored. A HDD  2520  is a hard disk drive that stores system software and image data. An image registering unit  2530 , an image inquiring unit  2531 , an image-comparing life-determining unit  2532 , and a life-expiration determining unit  2533  are functions of the software stored in the HDD  2520  that the server control unit  2510  executes. A network I/F  2521  is connected to the LAN  1013  to input and output information. 
     The image registering unit  2530  registers a bitmap image of a printed image transmitted from the copier  150  with the HDD  2520  using the printer serial number  5001  and the page count  5002  in the additional print information as keys. The image inquiring unit  2531  acquires print image data (a bitmap image) from the HDD  2520  on the basis of the printer serial number  5001  and the page count  5002  in the additional print information transmitted when a request to determine the life is given from the image-determination requesting unit  1203 . The image-comparing life-determining unit  2532  compares the print image data and the scanned image data to determine the lives of the process cartridges  5 . The life-expiration determining unit  2533  checks whether a process cartridge  5  that has come to the end of life in the copier  150  used for printing has been replaced and instructs the copier  150  to replace the process cartridge  5 . In this embodiment, when the image-comparing life-determining unit  2532  determines that the cartridges  5  has come to the end of life, the life-expiration determining unit  2533  inquires of the copier  150  the serial number of the mounted cartridge  5 . If the result (serial number) is the same as the cartridge serial number stored in the additional print information, the life-expiration determining unit  2533  determines that the process cartridge  5  has not been replaced and instructs the copier  150  to replace the process cartridge  5 . 
     Conceptual Diagram 
       FIG. 8  is a conceptual diagram of the sequence of determining the lives of the replaceable items by image analysis in the network configuration of this embodiment. A job that the user transmits from the host computer  160  is received by the copier  150  via the print server  161  (S 1 ). The copier  150  embeds additional print information in the job data (S 2 - 1 ) and prints the job data (S 2 - 2 ). The copier  150  registers a printed image of the job data with the life-expiration determining server  162  (S 2 - 3 ). The user that holds the printed paper issues an instruction to copy or scan the printed paper to one of the copiers  150  (S 3 ). The copier  150  scans the data on the printed paper (S 4 - 1 ) and extracts the additional print information from the output scanned image data (S 4 - 2 ). The copier  150  transmits the scanned image and the additional print information to the life-expiration determining server to request to determine the life (S 4 - 3 ). The life-expiration determining server  162  acquires the print image data registered at S 2 - 3  on the basis of the additional print information extracted at S 4 - 2  and compares the print image data with the scanned image data to determine the lives of the replaceable items. If it is determined that the life of any of the replaceable items is expired, the life-expiration determining server  162  issues an instruction to replace the replaceable item to the copier  150  used for printing (S 5 ). 
     Flowcharts 2 
     The details of the control will be described with reference to flowcharts.  FIG. 9  is a flowchart for the operation of the controller  1000  of the copier  150  when the user gives an instruction to print an image.  FIG. 10  is a flowchart for the operation of the controller  1000  of the copier  150  when the user gives an instruction to scan a printed image.  FIG. 11  is a flowchart for the operation of the life-expiration determining server  162  when the user gives an instruction to scan a printed image. 
     First, the flowchart for the operation of the controller  1000  of the copier  150  when the user gives an instruction to print an image will be described with reference to  FIG. 9 . A job described in a PDL is transmitted to the copier  150  via the LAN  1013 , and the controller control unit  1010  starts to execute the job (S 200 ). The controller control unit  1010  converts the transmitted PDL to a bitmap image with the raster image processor  1030  (S 201 ). The controller control unit  1010  determines whether the estimated toner level of at least one of the process cartridges  5 , which has received from the engine control unit  2010  at the job starting point, is lower than a threshold value (S 203 ). If the toner level is lower than the threshold value, the controller control unit  1010  sets an image-analysis request flag to TRUE (S 204 ), and if the toner level is not lower than the threshold value, the controller control unit  1010  sets the image-analysis request flag to FALSE (S 205 ). The controller control unit  1010  then prepares the additional print information shown in  FIG. 7  (S 206 ). The print date  5000  is acquired from a real-time clock IC (not shown) of the copier  150 . The printer SN  5001  and the page count  5002  are set from the information stored in the HDD  1020 . The image analysis request  5003  is set from the image-analysis request flag set at S 203  or S 204 . The cartridge serial number (CRG SN)  5004 , which is identification information, is acquired from the cartridge memory  2200  by the engine control unit  2010 . A QR code is added to the margin of the bitmap image on the basis of these additional print information (S 207 ). The bitmap image is converted to a data format for the engine  2000  by the engine-image processing unit  1034  (S 208 ). If the image-analysis request flag is TRUE, the bitmap image is registered with the life-expiration determining server  162  by the image registering unit  1201  (S 209  and S 210 ). The controller  1000  issues an instruction to start printing to the engine  2000  to perform printing (S 211 ). 
     Next, the operation of the controller  1000  when the user gives an instruction to scan printed paper will be described with reference to  FIG. 10 . The controller  1000  receives an instruction to scan a document from the user (S 220 ). The controller  1000  scans the document with the document scanning unit  200  to acquire a bitmap image (S 221 ). Next, the barcode analyzing unit  1202  searches the scanned bitmap image for a QR code in the margin and extracts additional print information from the QR code, if present (S 222 ). If the QR code is present (S 223 ), the controller  1000  determines whether the image analysis request  5003  in the extracted additional print information is TRUE (S 224 ). If the image analysis request  5003  is TRUE, the image-determination requesting unit  1203  transmits the scanned image to the life-expiration determining server  162  to request to determine the expiration of the life (S 225 ). 
     The operation of the life-expiration determining server  162  will be described with reference to  FIG. 11 . The life-expiration determining server  162  receives additional print information and scanned image data (a bitmap image) transmitted from the copier  150  (S 240 ). The image inquiring unit  2531  acquires print image data (a bitmap image) used for printing from the additional print information (S 241 ). The image-comparing life-determining unit  2532  compares the scanned bitmap image with the bitmap image used for printing (S 242 ). The image-comparing life-determining unit  2532  determines whether the average darkness of the scanned image is lower than (lighter than) the average darkness of the printed image by a predetermined threshold value, as the image-comparing life-determining unit  1041  of the first embodiment does (S 243 ). If the average darkness of the scanned image is lighter (smaller than or equal to the threshold value), the life-expiration determining unit  2533  inquires of the copier  150  the serial numbers of cartridges  5  mounted at the present (S 244 ). The image-comparing life-determining unit  2532  compares the cartridge serial numbers in the additional print information with the cartridge serial numbers received from the copier  150  to determine whether there is a difference (S 245 ). If the cartridge serial numbers are the same, the cartridges  5  have not been replaced, and the image-comparing life-determining unit  2532  notifies the copier  150  that the cartridges  5  have come to the end of the lives to prompt to replace the cartridges  5  (S 246 ). 
     This is a method for determining the lives of replaceable items of a copier used for printing from the analysis of the printed image and the scanned image when a user copies or scans printed paper. 
     Thus, according to this embodiment, when a user copies or scans printed paper under an environment in which a copier  150  or a single-function printer is connected to a network, the lives of the replaceable items of the device used for printing on the paper can be determined. This embodiment allows the lives of replaceable items to be determined by image analysis using the function of the existing printer, thus allowing the user to determine the lives of the replaceable items with no hassle operation. 
     While in this embodiment a device that the user uses for printing is the copier  150 , a single-function printer having no image scanning function and only capable of printing may be used. Furthermore, while in this embodiment the items illustrated in  FIG. 8  are defined as additional print information, the items are not limited to the items illustrated in  FIG. 8  because any other items that specify a printed image for use in printing may be used. For example, the cartridge serial number  5004  may not be included in the additional print information but may be registered as date with the life-expiration determining server  162 . While the image analysis is executed by the life-expiration determining server  162 , the image analysis may be executed by a copier used for scanning or a copier used for printing. 
     This embodiment may also be applied to a configuration in which a scanning unit having only a function of scanning documents is connected to a network. The above life determination may be executed by scanning a document using one of a copier, a printer, and a scanner connected to a network. 
     As in first embodiment, this embodiment is applicable to replaceable items that decrease in durability, such as the photoconductor  1 , the intermediate transfer belt (intermediate transfer member)  8 , the fusing roller  18  and the pressure roller  19  of the fuser  17 , and the feed roller  14  of the feeding conveying unit  12 . For this purpose, an algorithm for analyzing signs in images peculiar to the individual replaceable items caused according to degradation is prepared. For the above replaceable items, for example, individual driving times are measured and accumulated, and control (for determining whether the accumulated driving time is larger than or equal to a threshold value) is performed on the basis of the measured driving time. 
     Third Embodiment 
     In the second embodiment, a method for determining the expiration of the lives of replaceable items by comparing a printed image stored in the life-expiration determining server  162  with a scanned image has been described. However, to store all printed images in the life-expiration determining server  162 , the life-expiration determining server  162  needs a large memory capacity. This embodiment proposes a method for reducing the memory capacity by extracting parameters (features) relating to the image analysis of replaceable items in advance and storing only the parameters (features). In the drawings of this embodiment, the same functions as those in the second embodiment are given the same referenced signs, and descriptions thereof will be omitted. 
     A flowchart for the operation of the controller  1000  of the copier  150  when the user gives an instruction to print an image is the same as the flowchart in  FIG. 9 .  FIG. 12  is a flowchart for the operation of the life-expiration determining server  162  when the controller  1000  gives an instruction to register the bitmap image with the life-expiration determining server  162  at S 210  in  FIG. 9 . A flowchart for the operation of the controller  1000  of the copier  150  when the user gives an instruction to scan the printed image is the same as the flowchart in  FIG. 10 . A flowchart for the operation of the life-expiration determining server  162  when the user gives an instruction to scan the printed image is illustrated in  FIG. 13 . 
     First, a flowchart for the operation of the life-expiration determining server  162  when instructed to register a printed image will be described with reference to  FIG. 12 . The life-expiration determining server  162  receives a printed bitmap image and additional print information (S 300 ) and calculates the average darkness of CMYK colors from the bitmap image (S 301 ). The life-expiration determining server  162  then registers the average darkness with the HDD  2520  using the printer serial number  5001  and the page count  5002  in the additional print information as keys (S 302 ). 
     Next, a flowchart for the operation of the life-expiration determining server  162  when receiving a scanned bitmap image will be described with reference to  FIG. 13 . The life-expiration determining server  162  receives additional print information and a scanned bitmap image transmitted from the copier  150  (S 340 ). The life-expiration determining server  162  acquires the average darkness printed during printing from the additional print information (S 341 ). The life-expiration determining server  162  calculates the average darkness of the individual colors of the scanned bitmap image (S 342 ). The image-comparing life-determining unit  2532  determines whether the average darkness of the scanned image is lower (lighter) than the average darkness of the printed image by a predetermined threshold value, as the image-comparing life-determining unit  1041  in the first embodiment does (S 343 ). If the average darkness is lower, the life-expiration determining unit  2533  inquires of the copier  150  used for printing to acquire the serial numbers of cartridges  5  mounted at the present (S 344 ). The image-comparing life-determining unit  2532  compares the cartridge serial numbers in the additional print information with the cartridge serial numbers received from the copier  150  to determine whether there is a difference (S 345 ). If the cartridge serial numbers are the same, the cartridges  5  have not been replaced, and the image-comparing life-determining unit  2532  notifies the copier  150  that the cartridges  5  have come to the end of the lives to prompt to replace the cartridges  5  (S 346 ). 
     According to the embodiment of the present invention, the capacity of data to be stored in the life-expiration determining server  162  can be small, thereby reducing the cost for the life-expiration determining server  162 . If the algorithm for determining whether the replaceable items have come to the end of lives can digitize the features of the images and can determine the expiration of the lives of the replaceable items by comparing the values, the embodiment can also be applied to replaceable items other than toner. 
     While in this embodiment image analysis is performed by the life-expiration determining server  162 , the process of calculating the average darkness and the determination of expiration of lives may be performed by the controller  1000  of a copier  150  that has scanned the paper. 
     While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions. 
     This application claims the benefit of Japanese Patent Application No. 2015-032064, filed Feb. 20, 2015, which is hereby incorporated by reference herein in its entirety.