JP2007256356A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of predicting at what time point an accident will occur since a current time point. <P>SOLUTION: The image forming apparatus successively performs: storing acquisition group data comprising a plurality of kinds of data acquired by various sensors 2 or the like to a hard disk at each time when prescribed timing arrives; storing data including inclination data of variation of values from a time point which goes up to a past rather than an acquisition time point only by a prescribed acquisition number-of-time part to the hard disk in addition to the plurality of the kinds of the data as normal group data used for multi-change amount analysis; and calculating abnormality determination index values based on a calculation result, newest acquisition group data and normal group data group after calculating the inclination data respectively of the plurality of the kinds of the data in the acquisition group data, based on the newest acquisition group data acquired by the various sensors 2 or the like and the past acquisition group data stored in the hard disk. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as a copying machine, a facsimile machine, a printer, and the like, and more particularly to improvement of means for determining the presence or absence of an abnormality in the apparatus.

  Conventionally, in various image forming apparatuses on the market, if a failure occurs, depending on the content, the apparatus cannot be used until the parts are replaced or cleaned, which causes inconvenience to the user. There is. In particular, an electrophotographic image forming apparatus has a relatively complicated configuration and a large number of parts. Therefore, if maintenance of various parts is not performed regularly, a failure may occur suddenly. Become.

  Therefore, the cumulative operating time of various parts and devices in the device such as the photoconductor and the developing device is sequentially counted by a counter, and when the count value reaches a predetermined upper limit value, the arrival of the replacement time for that part is notified. An image forming apparatus is known. According to such a configuration, it is possible to periodically urge the user or maintenance service organization to replace parts or devices.

  However, since the arrival time of the life of parts and equipment does not show a complete correlation with the accumulated operating time, the above upper limit value is set with a considerable margin in order to reliably detect the timing before the occurrence of a failure. There is a need. As a result, there has actually been a problem of prompting the replacement of parts and devices even though there is still a sufficient margin until the end of the service life.

  On the other hand, conventionally, various methods for measuring the normality of a subject to be examined by multivariate analysis are known. For example, the MTS (Maharanobis Taguchi System) method described in Non-Patent Document 1 is one of them. In the MTS method, first, normal set data composed of a plurality of types of data is acquired from a test subject in a normal state or one having the same specification as the subject. A large number of normal group data is collected to construct a normal group data group. Thereafter, when it is desired to examine the normality of the subject to be examined, the obtained set data including the same type of data as the normal set data is obtained from the subject. Then, for the acquired set data, a Mahalanobis distance that is an abnormality determination index value indicating what kind of relative positional relationship is present in the multi-dimensional space by the normal set data group constructed in advance is obtained, and based on the result Measure the normality of the test subject. Not only the MTS method but also other multivariate analysis such as a principal component analysis method can be used to measure the normality of the test object based on the normal set data group and the acquired set data.

  If it is determined whether or not there is an abnormality in the image forming apparatus based on such multivariate analysis, it is possible to detect an appropriate replacement time according to the actual degree of deterioration of the component or device.

"Technology development in MT system" Publication Committee Chairman Genichi Taguchi Published by Japanese Standards Association

  However, the speed of deterioration of components and equipment varies depending on various factors, for example, foreign matter is caught between components. In multivariate analysis, it is possible to accurately detect when the normality has decreased to some extent, in other words, when the deterioration of parts or equipment has progressed to some extent. However, since the progress rate of deterioration cannot be grasped, it has not been possible to predict how long a failure will occur after that. For a user, information about how long the apparatus can be operated without replacement after the prompt for replacement of parts and devices may be very important. Especially for users who intensively print a large amount of printouts at a certain time, or on holidays or at night, if the timing from when parts are urged to when they are actually replaced, There is a risk that a failure will occur and the work will be hindered.

  The present invention has been made in view of the above background, and an object thereof is to provide the following image forming apparatus. In other words, the image forming apparatus can predict how long a failure has occurred from the present time.

In order to achieve the above object, the invention of claim 1 is directed to an image forming unit that forms an image on a recording member, a data acquisition unit that acquires a plurality of types of data from the image forming unit, and the plurality of normal values. Data storage means for storing a normal set data group that is a collection of normal set data including types of data, acquired set data composed of a plurality of types of data acquired by the data acquisition means, and stored in the data storage means In an image forming apparatus comprising an index value calculation unit that calculates an abnormality determination index value based on a normal group data group, the acquired group data acquired by the data acquisition unit is updated each time a predetermined timing arrives. Storage control means for sequentially storing the data in the data storage means is provided, and the normal set data is not limited to the above-described plural types of data, Each of the data storage means stores data including slope data of value fluctuations from the time point that is a predetermined number of times before the acquisition time point to the acquisition time point. Based on the latest acquired set data acquired by the means and the past acquired set data stored in the data storage means, the inclination data is obtained for each of the plurality of types of data in the acquired set data. After the calculation, the index value calculation means is configured to calculate the abnormality determination index value based on the calculation result, the latest acquired set data, and the normal set data group. It is.
According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, in addition to the plurality of types of data and the plurality of inclination data individually corresponding to the plurality of types, the plurality of types of normal set data. Each of the data is stored in the data storage means including the coefficient of variation data between the acquisition time point and a time point that is a predetermined number of acquisitions before the acquisition time point, and the data acquisition means The inclination data and fluctuations for each of the plurality of types of data in the acquired set data based on the latest acquired set data acquired by the above and the acquired set data in the past stored in the data storage means. After calculating the coefficient data, the abnormality determination index value is calculated based on the calculation result, the latest acquired set data, and the normal set data group. That constitute the index value calculation to is characterized in.
According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, the acquisition unit data acquired by the data acquisition unit during a predetermined first period is provided. The normal group data group is constructed based on the above, and the predetermined coefficient based on the acquired group data acquired by the data acquisition unit during the subsequent second period and the number of failure occurrences counted by the counting unit And the abnormality determination index calculated based on the acquired set data acquired by the data acquisition means during the subsequent third period, the inclination data based on the acquired set data, and the normal set data group By multiplying the value by the predetermined coefficient, prediction of the number of occurrences of failures from the time when the latest acquired set data is acquired to the future time when the data acquisition for the predetermined number of times is performed It is characterized in that it has to make determined.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first or second aspect, the acquisition unit data acquired by the data acquisition unit during a predetermined first period is provided. The normal group data group is constructed based on the obtained group data, a predetermined coefficient is calculated based on the acquired group data and the number of failure occurrences counted by the counting means, and the data is obtained during the subsequent second period. The latest acquisition by multiplying the abnormality determination index value calculated based on the acquired set data acquired by the acquiring means, the inclination data based on the acquired set data, and the normal set data group by the predetermined coefficient. It is characterized in that a predicted value of the number of occurrences of failures from the time when the set data is acquired to the future time point when the predetermined number of times of data acquisition is performed is obtained. .
According to a fifth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, the predetermined number of times from the time when the latest acquired set data is acquired based on an average operating time per day of the image forming unit. Correction means for correcting the period up to a future time point at which minute data acquisition is performed, and notifying means for notifying the number of occurrences as a predicted value of the number of occurrences of failures in the corrected period It is what.
According to a sixth aspect of the present invention, in the image forming apparatus according to the third or fourth aspect, from the time when the latest acquired set data is acquired based on the average number of recording member outputs per day of the image forming means. Provided correction means for correcting the period up to a future time point at which the predetermined number of times of data acquisition is performed, and provided notification means for notifying the number of occurrences as a predicted value of the number of occurrences of failures in the period after correction. It is a feature.

  In these inventions, in addition to various types of data such as sensing data that can be acquired by the data acquisition means, each of the data from the time point that has been acquired a predetermined number of times before the acquisition time point to the acquisition time point. The slope data of the fluctuation of the value between them is included in each normal group data in the normal group data group. Then, as data for comparison with the normal group data group, in addition to the acquired group data acquired by the data acquisition unit, the same inclination data for various data included therein is used to calculate the abnormality determination index value. . The abnormality determination index value calculated in this way reflects the inclination of fluctuation of normality in the current member or device, that is, the progress speed of deterioration. For this reason, the magnitude of the abnormality determination index value does not simply indicate whether the image forming unit is normal or not, but indicates both normality and the deterioration speed. Even if the normality is somewhat deteriorated, the abnormality determination index value is close to the normal value if the progress rate of deterioration is relatively slow. On the other hand, even if the normality is moderately good, the abnormality determination index value deviates from the normal value if the deterioration progressing speed is considerably high. Such an abnormality determination index value is different from the conventional abnormality determination index value indicating that the predetermined degree of deterioration has been reached for the test object by reaching a predetermined threshold, and depending on its magnitude, It will indicate whether or not a failure will occur when a certain amount of time has passed. Therefore, based on the magnitude of the abnormality determination index value, it is possible to predict how much time has passed since the present time when the failure occurs.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic copying machine (hereinafter simply referred to as a copying machine) as an image forming apparatus will be described.
First, a basic configuration of the copying machine according to the present embodiment will be described. FIG. 1 is a schematic configuration diagram showing the copying machine. The copier includes an image forming unit including a printer unit 100 and a paper feeding unit 200, a scanner unit 300, and a document conveying unit 400. The scanner unit 300 is mounted on the printer unit 100, and a document transport unit 400 including an automatic document transport device (ADF) is mounted on the scanner unit 300.

  The scanner unit 300 reads the image information of the document placed on the contact glass 32 by the reading sensor 36 and sends the read image information to a control unit (not shown). Based on the image information received from the scanner unit 300, the control unit controls lasers and LEDs (not shown) disposed in the exposure device 21 of the printer unit 100 to provide four drum-shaped photoconductors 40K, Y, and M. , C is irradiated with laser writing light L. By this irradiation, an electrostatic latent image is formed on the surface of the photoreceptors 40K, Y, M, and C, and this latent image is developed into a toner image through a predetermined development process. Note that the subscripts K, Y, M, and C added after the reference numerals indicate specifications for black, yellow, magenta, and cyan.

  In addition to the exposure device 21, the printer unit 100 includes primary transfer rollers 62K, Y, M, and C, a secondary transfer device 22, a fixing device 25, a paper discharge device, a toner supply device (not shown), a toner supply device, and the like. Yes.

  The paper feeding unit 200 includes an automatic paper feeding unit disposed below the printer unit 100 and a manual feeding unit disposed on a side surface of the printer unit 100. The automatic paper feed unit separates the two paper feed cassettes 44 arranged in multiple stages in the paper bank 43, the paper feed roller 42 that feeds transfer paper as a recording medium from the paper feed cassette, and the fed transfer paper. A separation roller 45 and the like are sent to the paper feed path 46. Further, it also includes a transport roller 47 that transports the transfer paper to the paper feed path 48 of the printer unit 100. On the other hand, the manual feed section includes a manual feed tray 51 and a separation roller 52 that separates transfer sheets on the manual feed tray 51 one by one toward the manual feed path 53.

  A registration roller pair 49 is disposed near the end of the paper feed path 48 of the printer unit 100. The registration roller pair 49 is formed between the intermediate transfer belt 10 serving as an intermediate transfer body and the secondary transfer device 22 at a predetermined timing after receiving the transfer paper sent from the paper feed cassette 44 or the manual feed tray 51. To the secondary transfer nip.

  In this copying machine, an operator sets a document on the document table 30 of the document transport unit 400 when copying a color image. Alternatively, after the document conveying unit 400 is opened and a document is set on the contact glass 32 of the scanner unit 300, the document conveying unit 400 is closed and the document is pressed. Then, a start switch (not shown) is pressed. Then, when an original is set on the original conveying unit 400, after the original is conveyed onto the contact glass 32, immediately after the original is set on the contact glass 32, the scanner unit 300 is driven. Start. Then, the first traveling body 33 and the second traveling body 34 travel, and the light emitted from the light source of the first traveling body 33 is reflected by the document surface and then travels toward the second traveling body 34. Further, after being reflected by the mirror of the second traveling body 34, it reaches the reading sensor 36 via the imaging lens 35 and is read as image information.

  When the image information is read in this way, the printer unit 100 rotates the other two support rollers while rotating one of the support rollers 14, 15, and 16 with a drive motor (not shown). Then, the intermediate transfer belt 10 stretched around these rollers is moved endlessly. Further, laser writing as described above and a development process described later are performed. Then, while rotating the photoconductors 40K, Y, M, and C, monochrome images of black, yellow, magenta, and cyan are formed on them. These are four-color superposed toners that are sequentially superposed and electrostatically transferred at the primary transfer nips for K, Y, M, and C where the photoreceptors 40K, Y, M, and C and the intermediate transfer belt 10 abut. Become a statue. Toner images are formed on the photoreceptors 40K, 40Y, 40M, and 40C.

  On the other hand, the paper feed unit 200 operates any one of the three paper feed rollers to feed the transfer paper having a size corresponding to the image information, and feeds the transfer paper to the paper feed path of the printer unit 100. Lead to 48. After the transfer paper that has entered the paper feed path 48 is sandwiched between the registration roller pair 49 and temporarily stopped, the intermediate transfer belt 10 and the secondary transfer roller 23 of the secondary transfer device 22 come into contact with each other at the appropriate timing. To the secondary transfer nip, which is a part. Then, in the secondary transfer nip, the four-color superimposed toner image on the intermediate transfer belt 10 and the transfer paper are brought into close contact in synchronization. Then, the four-color superimposed toner image is secondarily transferred onto the transfer paper due to the influence of the transfer electric field formed at the nip, the nip pressure, etc., and becomes a full color image combined with the white color of the paper.

  The transfer paper that has passed through the secondary transfer nip is fed into the fixing device 25 by the endless movement of the transport belt 24 of the secondary transfer device 22. Then, after the full color image is fixed by the action of the pressure applied by the pressure roller 27 of the fixing device 25 and the heating by the heating belt, the paper discharge tray 57 provided on the side surface of the printer unit 100 via the discharge roller 56. Discharged to the top.

  FIG. 2 is an enlarged configuration diagram illustrating the printer unit 100. The printer unit 100 includes a belt unit, four process units 18K, Y, M, and C that form toner images of respective colors, a secondary transfer device 22, a belt cleaning device 17, a fixing device 25, and the like.

  The belt unit moves the intermediate transfer belt 10 stretched around a plurality of rollers endlessly while contacting the photoreceptors 40K, Y, M, and C. In the primary transfer nip for K, Y, M, and C where the photoreceptors 40K, Y, M, and C are brought into contact with the intermediate transfer belt 10, the intermediate transfer belt 10 is driven by the primary transfer rollers 62K, Y, M, and C. Is pressed from the back side toward the photoconductors 40K, Y, M, and C. A primary transfer bias is applied to the primary transfer rollers 62K, Y, M, and C by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoreceptors 40K, Y, M, and C toward the intermediate transfer belt 10 is formed in the primary transfer nips for K, Y, M, and C. Has been. Between each primary transfer roller 62K, Y, M, and C, a conductive roller 74 that is in contact with the back surface of the intermediate transfer belt 10 is disposed. In these conductive rollers 74, the primary transfer bias applied to the primary transfer rollers 62K, Y, M, and C is applied to adjacent process units via the intermediate resistance base layer 11 on the back side of the intermediate transfer belt 10. It prevents the flow.

  The process unit (18K, Y, M, C) supports the photosensitive member (40K, Y, M, C) and several other devices as a single unit on a common support. The unit 100 is detachable. Taking the black process unit 18K as an example, this has a developing unit 61K as developing means for developing the electrostatic latent image formed on the surface of the photosensitive member 40K into a black toner image in addition to the photosensitive member 40K. ing. Further, it also has a photoreceptor cleaning device 63K that cleans transfer residual toner adhering to the surface of the photoreceptor 40K after passing through the primary transfer nip. Further, there are a static elimination device (not shown) that neutralizes the surface of the photoreceptor 40K after cleaning, a charging device (not shown) that uniformly charges the surface of the photoreceptor 40K after static elimination, and the like. The process units 18Y, M, and C for other colors have almost the same configuration except that the color of the toner to be handled is different. The copying machine has a so-called tandem configuration in which these four process units 18K, Y, M, and C are arranged so as to face the intermediate transfer belt 10 along the endless movement direction.

  FIG. 3 is a partially enlarged view showing a part of the tandem unit 20 including the four process units 18K, Y, M, and C. Since the four process units 18K, Y, M, and C have substantially the same configuration except that the colors of the toners to be used are different, K, Y, M, and C attached to the respective reference numerals in FIG. The subscript is omitted. As shown in the figure, the process unit 18 includes a charging device 60 as a charging unit, a developing device 61, a primary transfer roller 62 as a primary transfer unit, a photoconductor cleaning device 63, a charge eliminating device around the photoconductor 40. A device 64 or the like is provided.

  As the photosensitive member 40, a drum-shaped member is used in which a photosensitive organic layer is applied to a base tube made of aluminum or the like to form a photosensitive layer. However, an endless belt may be used. In addition, as the charging device 60, a charging device to which a charging roller to which a charging bias is applied is rotated while being in contact with the photoreceptor 40 is used. A scorotron charger or the like that performs a non-contact charging process on the photoreceptor 40 may be used.

  The developing device 61 develops a latent image using a two-component developer containing a magnetic carrier and a nonmagnetic toner. An agitating unit 66 that conveys the two-component developer accommodated in the inside while stirring and supplies the developer sleeve 65 to the developing sleeve 65; , C, a developing unit 67 for transferring to C.

  The stirring unit 66 is provided at a position lower than the developing unit 67, and includes two screws 68 arranged in parallel to each other, a partition plate provided between the screws, and a toner provided on the bottom surface of the developing case 70. It has a density sensor 71 and the like.

  The developing unit 67 includes a developing sleeve 65 that faces the photosensitive member 40 through the opening of the developing case 70, a magnet roller 72 that is non-rotatably provided inside the developing sleeve 65, a doctor blade 73 that approaches the developing sleeve 65, and the like. ing. The distance at the closest portion between the doctor blade 73 and the developing sleeve 65 is set to about 500 [μm]. The developing sleeve 65 has a non-magnetic rotatable sleeve shape. In addition, the magnet roller 72 that is prevented from being rotated around the developing sleeve 65 has, for example, five magnetic poles N1, S1, N2, S2, and S3 in the rotation direction of the developing sleeve 65 from the position of the doctor blade 73. ing. Each of these magnetic poles applies a magnetic force to the two-component developer on the sleeve at a predetermined position in the rotation direction. As a result, the two-component developer sent from the stirring unit 66 is attracted and carried on the surface of the developing sleeve 65, and a magnetic brush is formed along the magnetic field lines on the sleeve surface.

  The magnetic brush is regulated to an appropriate layer thickness when passing through the position facing the doctor blade 73 as the developing sleeve 65 rotates, and then conveyed to the developing area facing the photoreceptor 40. Then, due to the potential difference between the developing bias applied to the developing sleeve 65 and the electrostatic latent image on the photoreceptor 40, it is transferred onto the electrostatic latent image and contributes to development. Further, as the developing sleeve 65 rotates, the developing sleeve 65 returns to the developing portion 67 again, and after being separated from the sleeve surface by the influence of the repulsive magnetic field between the magnetic poles of the magnet roller 72, the developing sleeve 65 is returned to the stirring portion 66. In the stirring unit 66, an appropriate amount of toner is supplied to the two-component developer based on the detection result by the toner density sensor 71. The developing device 61 may employ a one-component developer that does not include a magnetic carrier, instead of the one that uses a two-component developer.

  As the photoconductor cleaning device 63, a system in which a cleaning blade 75 made of polyurethane rubber is pressed against the photoconductor 40 is used, but another system may be used. In order to improve the cleaning property, in this example, a cleaning device 63 having a contact conductive fur brush 76 whose outer peripheral surface is in contact with the photoreceptor 40 is rotatable in the direction of the arrow in the figure. A metal electric field roller 77 for applying a bias to the fur brush 76 is provided so as to be rotatable in the direction of the arrow in the figure, and the tip of the scraper 78 is pressed against the electric field roller 77. The toner removed from the electric field roller 77 by the scraper 78 falls on the collection screw 79 and is collected.

  The photoconductor cleaning device 63 having such a configuration removes residual toner on the photoconductor 40 with a fur brush 76 that rotates in the counter direction with respect to the photoconductor 40. The toner adhering to the fur brush 76 is removed by the electric field roller 77 to which a bias that rotates in contact with the fur brush 76 in the counter direction is applied. The toner adhering to the electric field roller 77 is cleaned by the scraper 78. The toner recovered by the photoconductor cleaning device 63 is brought to one side of the photoconductor cleaning device 63 by the recovery screw 79 and returned to the developing device 61 by the toner recycling device 80 for reuse.

  The static eliminator 64 includes a static elimination lamp or the like, and removes the surface potential of the photoreceptor 40 by irradiating light. The surface of the photoreceptor 40 thus neutralized is uniformly charged by the charging device 60 and then subjected to optical writing processing.

  A secondary transfer device 22 is provided below the belt unit in the figure. In the secondary transfer device 22, a secondary transfer belt 24 is stretched between two rollers 23 and moved endlessly. One of the two rollers 23 is a secondary transfer roller to which a secondary transfer bias is applied by a power source (not shown), and the intermediate transfer belt 10 and the secondary transfer belt 24 are between the roller 16 of the belt unit. Is sandwiched. Thus, a secondary transfer nip is formed in which both belts move in the same direction at the contact portion while contacting. On the transfer paper fed from the registration roller pair 49 to the secondary transfer nip, the four-color superimposed toner image on the intermediate transfer belt 10 is secondarily transferred collectively under the influence of the secondary transfer electric field and the nip pressure, so that full color is obtained. An image is formed. The transfer sheet that has passed through the secondary transfer nip is separated from the intermediate transfer belt 10 and is conveyed to the fixing device 25 along with the endless movement of the belt while being held on the surface of the secondary transfer belt 24. Instead of the secondary transfer roller, secondary transfer may be performed by a transfer charger or the like.

  The surface of the intermediate transfer belt 10 that has passed through the secondary transfer nip approaches a support position by the support roller 15. Here, the intermediate transfer belt 10 is sandwiched between a belt cleaning device 17 that contacts the front surface (loop outer surface) and a support roller 15 that contacts the back surface. Then, after the transfer residual toner adhering to the front surface is removed by the belt cleaning device 17, it sequentially enters the primary transfer nip for K, Y, M, and C, and the next four-color toner The images are superimposed.

  The belt cleaning device 17 has two fur brushes 90 and 91. By rotating a plurality of raised brushes in contact with the intermediate transfer belt 10 in a counter direction with respect to the flocking direction, the transfer residual toner on the belt is mechanically scraped off. In addition, a cleaning bias is applied by a power source (not shown) to electrostatically attract and recover the scraped transfer residual toner.

  With respect to the fur brushes 90 and 91, the metal rollers 92 and 93 are rotating in the forward or reverse direction while being in contact with each other. Among these metal rollers 92 and 93, a negative polarity voltage is applied to the metal roller 92 located on the upstream side in the rotation direction of the intermediate transfer belt 10 by the power source 94. Further, a positive polarity voltage is applied to the metal roller 93 located on the downstream side by the power source 95. The tips of the blades 96 and 97 are in contact with the metal rollers 92 and 93, respectively. In such a configuration, the upstream fur brush 90 first cleans the surface of the intermediate transfer belt 10 with the endless movement of the intermediate transfer belt 10 in the direction of the arrow in the drawing. At this time, for example, when −400 [V] is applied to the fur brush 90 while −700 [V] is applied to the metal roller 92, first, the positive polarity toner on the intermediate transfer belt 10 is moved to the fur brush 90 side. Electrostatic transfer to The toner transferred to the fur brush side is further transferred from the fur brush 90 to the metal roller 92 due to a potential difference, and is scraped off by the blade 96.

  As described above, the toner on the intermediate transfer belt 10 is removed by the fur brush 90, but a lot of toner still remains on the intermediate transfer belt 10. These toners are negatively charged by a negative polarity bias applied to the fur brush 90. This is considered to be charged by charge injection or discharge. Next, by using the fur brush 91 on the downstream side to apply a positive polarity bias and perform cleaning, the toner can be removed. The removed toner is transferred from the fur brush 91 to the metal roller 93 due to a potential difference and scraped off by the blade 97. The toner scraped off by the blades 96 and 97 is collected in a tank (not shown).

  Most of the toner is removed from the surface of the intermediate transfer belt 10 after being cleaned by the fur brush 91, but a little toner is still left. The toner remaining on the intermediate transfer belt 10 is charged with a positive polarity by a positive polarity bias applied to the fur brush 91 as described above. Then, it is transferred to the photoconductors 40K, Y, M, and C by the transfer electric field applied at the primary transfer position, and is collected by the photoconductor cleaning device 63.

  In general, the registration roller pair 49 is often used while being grounded. However, a bias can be applied to remove the paper dust of the transfer paper P.

  Under the secondary transfer device 22 and the fixing device 25, a transfer paper reversing device 28 (see FIG. 1) is provided so as to extend in parallel with the tandem portion 20 described above. As a result, the transfer paper that has undergone the image fixing process on one side is switched by the switching claw to the transfer paper path to the transfer paper reversing device side, where it is reversed and enters the secondary transfer transfer nip again. Then, after the secondary transfer process and the fixing process of the image are performed on the other side, the sheet is discharged onto a discharge tray.

  The copying machine includes data acquisition means for acquiring various information related to the state of the components and phenomena occurring inside. This data acquisition means includes the control unit 1, various sensors 2, and the operation display unit 3 shown in FIG. The control unit 1 is a control unit that controls the entire copying machine, and includes a ROM 1c that is a data storage unit that stores a control program, a RAM 1b that is a data storage unit that stores operation data, control parameters, and the like, a CPU 1a, and the like. ing. It also has a hard disk (not shown) as data storage means. The operation display unit 3 includes a display unit 3a composed of a liquid crystal display for displaying character information and the like, an operation unit 3b for receiving input data from an operator using a numeric keypad and the like and sending it to the control unit 1c. . In this copying machine, the data acquisition means composed of the control unit 1, various sensors 2, the operation display unit 3 and the like is transmitted from the copying machine and the normal set data group stored in the data storage means such as the ROM (1c). It also functions as index value calculation means for calculating an abnormality determination index value described later based on the acquired set data. It also functions as a storage control means for sequentially storing the acquired set data acquired by the data acquisition means in the hard disk as the data storage means every time a predetermined timing arrives.

  Examples of various data acquired by the data acquisition unit of the copying machine include sensing data, control parameter data, input data, and image reading data. Hereinafter, these data will be described in detail.

(A) Sensing data Sensing data is considered to be a target for acquiring drive relationships, various characteristics of recording media, developer characteristics, photoreceptor characteristics, various process conditions of electrophotography, environmental conditions, various characteristics of recorded materials, etc. . The outline of these sensing data is as follows.

(A-1) Drive system data / The rotational speed of the photosensitive drum is detected by an encoder, the current value of the drive motor is read, and the temperature of the drive motor is read.
Similarly, the drive state of a cylindrical or belt-like rotating part such as a fixing roller, a paper transport roller, or a drive roller is detected.
-Detect sound generated by driving with a microphone installed inside or outside the device.

(A-2) Paper transport status • The position of the leading or trailing edge of the transported paper is read using a transmissive or reflective optical sensor or contact type sensor to detect that a paper jam has occurred. Reads deviations in the passage timing of the leading and trailing edges of the paper and fluctuations in the direction perpendicular to the feeding direction.
Similarly, the paper moving speed is obtained based on the detection timing between a plurality of sensors.
The slip between the paper supply roller and the paper during paper supply is obtained by comparing the measured value of the rotation speed of the roller with the amount of movement of the paper.

(A-3) Various characteristics of recording media such as paper This data greatly affects the image quality and stability of sheet conveyance. There are the following methods for acquiring the paper type data.
-The thickness of the paper should be equal to the amount of movement of the member pushed up when the paper is sandwiched between two rollers and the relative positional displacement of the rollers is detected by an optical sensor or the paper enters. Find by detecting.
-The surface roughness of the paper is such that a guide or the like is brought into contact with the surface of the paper before transfer, and vibrations or sliding noises caused by the contact are detected.
-For the gloss of paper, a light beam with a specified opening angle is incident at a specified incident angle, and a light beam with a specified opening angle reflected in the specular reflection direction is measured by a sensor.
The paper rigidity is obtained by detecting the amount of deformation (curvature) of the pressed paper.
The judgment as to whether or not the paper is recycled is made by irradiating the paper with ultraviolet rays and detecting its transmittance.
The determination as to whether the paper is a backing paper is performed by irradiating light from a linear light source such as an LED array and detecting the light reflected from the transfer surface with a solid-state image sensor such as a CCD.
Whether or not the sheet is for OHP is determined by irradiating the paper with light and detecting regular reflection light having a different angle from the transmitted light.
-The amount of water contained in the paper is determined by measuring the Kyushu of infrared or microwave light.
-The amount of curl is detected by an optical sensor, contact sensor, etc.
-The electrical resistance of the paper is measured directly by contacting a pair of electrodes (such as paper feed rollers) with the recording paper, or by measuring the surface potential of the photoconductor or intermediate transfer body after paper transfer, and recording from that value. Estimate the resistance of the paper.

(A-4) Developer characteristics The characteristics of the developer (toner and carrier) in the apparatus affect the basic function of the electrophotographic process. Therefore, it becomes an important factor for the operation and output of the system. Obtaining developer information is extremely important. Examples of the developer characteristics include the following items.
-For toner, list charge amount and distribution, fluidity, cohesion, bulk density, electrical resistance, amount of external additive, consumption or remaining amount, fluidity, toner concentration (mixing ratio of toner and carrier) Can do.
-As for carriers, magnetic properties, coat film thickness, spent amount, etc. can be mentioned.
It is usually difficult to detect these data alone in a copying machine. Therefore, it may be detected as a comprehensive characteristic of the developer. The overall characteristics of this developer can be measured, for example, as follows.
A test latent image is formed on the photoconductor, developed under predetermined development conditions, and the reflection density (light reflectance) of the formed toner image is measured.
A pair of electrodes is provided in the developing device, and the relationship between applied voltage and current is measured (resistance, dielectric constant, etc.).
-Install a coil in the developing device and measure the voltage-current characteristics (inductance).
-A level sensor is provided in the developing device to detect the developer capacity. The level sensor includes an optical type and a capacitance type.

(A-5) Photoreceptor characteristics Like the developer characteristics, the photoreceptor characteristics are closely related to the function of the electrophotographic process. The photoconductor characteristics data include photoconductor film thickness, surface characteristics (friction coefficient, unevenness), surface potential (before and after each process), surface energy, scattered light, temperature, color, surface position (flare), linear velocity. , Potential decay rate, electrical resistance, capacitance, surface moisture content and the like. Among these, the following data can be detected in the copying machine.
・ Detect the current flowing from the charging member to the photoconductor, and simultaneously compare the change in capacitance with the change in film thickness with the voltage-current characteristics with respect to the voltage applied to the charging member and the preset dielectric thickness of the photoconductor. Thus, the film thickness is obtained.
-The surface potential and temperature can be determined by a conventionally known sensor.
-The linear velocity is detected by an encoder attached to the photoconductor rotating shaft.
-Scattered light from the surface of the photoreceptor is detected by an optical sensor.

(A-6) Electrophotographic process state As is well known, electrophotographic toner image formation is performed by uniformly charging the photoreceptor, forming a latent image (image exposure) using laser light, etc., and charged toner (colored particles). Development by transfer, transfer of toner image onto transfer material (in the case of color, overlay on the recording medium that is the intermediate transfer body or final transfer material, or over development on the photoreceptor during development), toner on the recording medium This is done in the order of image fixing. Various information at each of these stages greatly affects the output of images and other systems. Obtaining these is important in evaluating the stability of the system. Specific examples of the electrophotographic process state data acquisition include the following.
The charging potential and the exposure portion potential are detected by a conventionally known surface potential sensor.
The gap between the charging member and the photosensitive member in non-contact charging is detected by measuring the amount of light that has passed through the gap.
・ Electromagnetic waves from electrification are captured by a broadband antenna.
・ Sound generated by charging.
-Exposure intensity.
-Exposure light wavelength.

Examples of the method for acquiring various states of the toner image include the following.
The pile height (the height of the toner image) is obtained by measuring the depth from the vertical direction with a displacement sensor and the light shielding length from the horizontal direction with a linear sensor of parallel light.
The toner charge amount is measured by a potential sensor that measures the potential of the electrostatic latent image on the solid part and the potential when the latent image is developed, and the ratio to the adhesion amount converted from the reflection density sensor at the same location. Ask for.
The dot fluctuation or dust is detected by detecting the dot pattern image with an infrared light area sensor on the photosensitive member and with an area sensor having a wavelength corresponding to each color on the intermediate transfer member, and performing appropriate processing.
The offset amount (after fixing) is obtained by reading the corresponding locations on the recording paper and the fixing roller with optical sensors and comparing them.
An optical sensor is installed after the transfer process (on the PD and on the belt), and the transfer remaining amount is determined based on the amount of reflected light from the transfer residual pattern after the transfer of the specific pattern.
-Detect color unevenness during overlay with a full-color sensor that detects the recording paper after fixing.

(A-7) The characteristic, image density and color of the formed toner image are optically detected. Either reflected light or transmitted light may be used. What is necessary is just to select a light projection wavelength according to a color. In order to obtain density and single color information, it may be on a photoconductor or an intermediate transfer body, but it is necessary on paper to measure a color combination such as color unevenness.
For gradation, the reflection density of the toner image formed on the photosensitive member or the toner image transferred to the transfer member is detected by an optical sensor for each gradation level.
Sharpness is obtained by reading an image in which a line repetition pattern is developed or transferred using a monocular sensor having a small spot diameter or a high-resolution line sensor.
The graininess (roughness) is obtained by reading a halftone image and calculating a noise component by the same method as the sharpness detection.
The registration skew is obtained from the difference between the registration roller ON timing and the detection timing of both sensors by providing optical sensors at both ends in the main scanning direction after registration.
Color misregistration is detected by a monocular small-diameter spot sensor or high-resolution line sensor at the edge portion of the superimposed image on the intermediate transfer member or recording paper.
Banding (density unevenness in the feed direction) measures density unevenness in the sub-scanning direction with a small-diameter spot sensor or high-resolution line sensor on the recording paper, and measures the signal amount of a specific frequency.
Glossiness (unevenness) is provided so that a recording paper on which a uniform image is formed is detected by a regular reflection optical sensor.
・ Fog is a method of reading the image background with an optical sensor that detects a relatively wide area on the photoconductor, intermediate transfer member, or recording paper, or image information for each area of the background with a high-resolution area sensor. And the number of toner particles contained in the image is counted.

(A-8) Image characteristics obtained by detecting the toner image on the photosensitive member, intermediate transfer member, or recording paper with an area sensor, such as physical characteristics, image flow and image fading of the printed material of the image forming apparatus Is determined by image processing.
The toner dust stain is obtained by taking an image on a recording sheet with a high resolution line sensor or an area sensor and calculating the amount of toner scattered around the pattern portion.
The trailing edge blank and the solid cross blank are detected by a high resolution line sensor on the photosensitive member, the intermediate transfer member, or the recording paper.
• Curling, undulation and crease of the recording paper are detected by a displacement sensor. In order to detect a fold, it is effective to install a sensor near the both ends of the recording paper.
-For the dirt and scratches on the edge surface, the area sensor is used to capture and analyze the edge surface when paper discharge has accumulated to some extent by the area sensor installed vertically on the paper discharge tray.

(A-9) For detecting environmental conditions and temperature, a thermocouple system that extracts the thermoelectromotive force generated at the contact point between dissimilar metals or between metal and semiconductor as a signal, the resistivity of metal or semiconductor changes with temperature Resistivity change element using this, pyroelectric element that generates a potential on the surface due to bias in the arrangement of charges in the crystal due to the rise in temperature in certain crystals, and magnetic characteristics depending on temperature It is possible to employ a thermomagnetic effect element or the like that detects the change of.
-For humidity detection, there are an optical measurement method for measuring light absorption of H ₂ O or OH group, a humidity sensor for measuring a change in electric resistance value of a material due to adsorption of water vapor, and the like.
・ Various gases are basically detected by measuring changes in the electrical resistance of the oxide semiconductor accompanying gas adsorption.
Although there are optical measurement methods and the like for detection of airflow (direction, flow velocity, gas type), an air bridge type flow sensor that can be made smaller in consideration of mounting on a system is particularly useful.
-There are methods for detecting pressure and pressure, such as using a pressure sensitive material and measuring the mechanical displacement of the membrane. A similar method is used for vibration detection.

(B) Control parameter data Since the operation of the copying machine is determined by the control unit, it is effective to directly use the input / output parameters of the control unit.

(B-1) Image Forming Parameters Direct parameters output by the control unit through image processing for image formation include the following examples.
A process condition setting value by the control unit, such as a charging potential, a developing bias value, a fixing temperature setting value, and the like.
-Similarly, setting values for various image processing parameters such as halftone processing and color correction.
Various parameters set by the control unit for the operation of the apparatus, for example, paper conveyance timing, execution time of the preparation mode before image formation, and the like.

(B-2) User operation history / frequency of various operations selected by the user, such as the number of colors, number of sheets, image quality instruction, etc./frequency of the paper size selected by the user.

(B-3) Power consumption / Total power consumption or its distribution, change amount (differentiation), cumulative value (integration), etc. for the whole period or for a specific period (1 day, 1 week, 1 month, etc.).

(B-4) Consumables consumption information-Total amount or specific period unit (1 day, 1 week, 1 month, etc.) toner, photoconductor, paper usage or distribution, change (differentiation), cumulative value ( Integration) etc.

(B-5) Failure occurrence information ・ Frequency or distribution of failure occurrence (by type), change amount (differentiation), cumulative value (integration) of whole period or specific period unit (1 day, 1 week, 1 month, etc.) Such.
(b-6) Operation time information (operation time information)
-The operation time of the copying machine is measured by a time measuring means and stored.
(b-7) Number of printing operations (operation frequency information)
-Count up for each printout and store the count value.

(C) Input image information The following information can be acquired from image information sent directly as data from the host computer or image information obtained after image processing is performed by reading a document image from a scanner.
The cumulative number of colored pixels is obtained by counting image data for each GRB signal for each pixel.
The original image can be separated into characters, halftone dots, photographs, and backgrounds by the method described in Japanese Patent No. 2621879, for example, and the ratio of the character part, halftone part, etc. can be obtained. Similarly, the ratio of color characters can be obtained.
The toner consumption distribution in the main scanning direction can be obtained by counting the cumulative value of the colored pixels for each area divided in the main scanning direction.
The image size is obtained from the distribution of colored pixels in the image size signal or image data generated by the control unit.
-Character type (size, font) is obtained from character attribute data.

Next, a specific method for acquiring various data in the copying machine will be described.
(1) Temperature data The copying machine includes a temperature sensor that acquires temperature information using a variable resistance element that is simple in principle and structure and that can be miniaturized.

(2) Humidity data Humidity sensors that can be made compact are useful. The basic principle is that when water vapor is adsorbed on moisture-sensitive ceramics, the ionic conduction is increased by the adsorbed water and the electrical resistance of the ceramics is reduced. The material of the moisture-sensitive ceramics is a porous material, and generally alumina-based, apatite-based, ZrO ₂ -MgO-based, etc. are used.

(3) Vibration data The vibration sensor is basically the same as a sensor that measures atmospheric pressure and pressure, and a silicon-based sensor that can be miniaturized is particularly useful in consideration of mounting in a system. It is possible to measure the movement of a vibrator fabricated on a thin silicon diaphragm by measuring the change in capacitance between the opposing electrodes provided facing the vibrator, or by using the piezoresistance effect of the Si diaphragm itself. it can.

(4) Toner density (for 4 colors) data The toner density is detected for each color and converted into data. A conventionally known toner density sensor can be used. For example, the toner concentration can be detected by a sensing system that measures changes in the magnetic permeability of the developer in the developing device as described in JP-A-6-289717.

(5) Photoconductor uniform charging potential (for four colors) data The uniform charging potential is detected for each color photoconductor (40K, Y, M, C). A known surface potential sensor that detects the surface potential of an object can be used.

(6) Data after exposure of photoreceptor (4 colors) data The surface potential of the photoreceptor (40K, Y, M, C) after optical writing is detected in the same manner as in (5).

(7) Colored area ratio (for four colors) data From the input image information, a colored area ratio is obtained for each color from the ratio of the cumulative value of pixels to be colored and the cumulative value of all pixels, and this is used.

(8) Development toner amount (for four colors) data The toner adhesion amount per unit area in each color toner image developed on the photosensitive member (40K, Y, M, C) is converted into the light reflectance by the reflection type photosensor. Ask based. The reflection type photosensor irradiates an object with LED light and detects the reflected light with a light receiving element. Since a correlation is established between the toner adhesion amount and the light reflectance, the toner adhesion amount can be obtained based on the light reflectance.

(9) Inclination of paper leading edge position An optical sensor that detects transfer paper at both ends in a direction orthogonal to the conveyance direction anywhere in the paper feed path from the paper feed roller of the paper feed unit (200) to the secondary transfer nip. A pair is installed to detect both ends near the leading edge of the transferred transfer paper. For both light sensors, the time to pass is measured with reference to the time when the drive signal of the paper feed roller is transmitted, and the inclination of the transfer paper with respect to the feed direction is obtained based on the time deviation.

(10) Paper discharge timing data The transfer paper after passing through the pair of discharge rollers (56 in FIG. 1) is detected by an optical sensor. In this case as well, the measurement is performed with reference to the time when the paper feed roller drive signal is transmitted.

(11) Photoconductor total current (for four colors) data The current flowing from the photoconductor (40K, Y, M, C) to the ground is detected. Such a current can be detected by providing a current measuring means between the substrate of the photoreceptor and the ground terminal.

(12) Photoconductor driving power (for four colors)
Driving power (current × voltage) consumed by the driving source (motor) of the photosensitive member during driving is detected by an ammeter, a voltmeter, or the like.

Next, a characteristic configuration of the copying machine will be described.
FIG. 5 is a flowchart showing a processing flow in long-term control that is performed over a relatively long period of time by the control unit 1 of the copying machine. The control unit 1 of the copying machine uses the above-mentioned acquired set data periodically acquired from when it is first used by the user after it is shipped from the factory until the predetermined first period has elapsed. Based on this, a normal data set is constructed. Specifically, the copying machine is shipped from the factory with the first flag being a control parameter set. The control unit 1 determines whether or not the first flag is being set. If the first flag is being set (step 1: hereinafter, the step is denoted as S), then, the acquisition that periodically arrives. The presence or absence of timing is monitored (S2). When the acquisition timing has arrived (Y in S2), the acquired set data is acquired based on output signals from various sensors and stored in the hard disk in association with the acquisition timing (S3). Next, normal group data is constructed based on the acquired group data as necessary and stored in the hard disk (S4). By repeating these processes until the first period elapses, a normal group data group composed of a plurality of normal group data is constructed. When the first period has elapsed (Y in S5), the first flag is canceled and the second flag is set (S6).

  When the construction of the normal group data group is completed in this way, thereafter, the control flow from S1 to S6 is omitted, and the control flow after S7 described later is executed. Then, until the predetermined second period elapses, prediction formula construction data acquisition for constructing a prediction formula for predicting the number of occurrences of failure is performed. Specifically, the control unit 1 first determines whether or not the second flag is being set. If the second flag is being set (Y in S7), the controller 1 monitors whether or not the acquisition timing has arrived ( S8). When the acquisition timing arrives (Y in S8), the acquired set data is acquired and stored in the hard disk (S9), and then it is determined whether or not a failure has occurred (S10). If a failure has occurred (Y in S10), the number of occurrences is stored in the hard disk in association with the acquisition timing (S11). Since it is unlikely that two or more failures occur at the same time, the number of occurrences “1” is usually stored in association with the acquisition timing, but may be “2” or more. As for the presence or absence of a failure, the control unit 1 automatically detects the failure that can be detected by a sensor or the like, and stores the number of occurrences in the hard disk. Further, the undetectable failure is detected by the control unit 1 based on an input operation to the operation display unit 3 by a user or a serviceman, and the number of occurrences is stored in the hard disk. By repeating these processes until the second period elapses, data for constructing the prediction formula is acquired. When the second period elapses (Y in S12), after the prediction formula is constructed based on the normal group data group stored in the hard disk and the data for constructing the prediction formula (S13), the second flag is cleared. (S14).

  When the construction of the prediction formula is completed in this way, thereafter, the control flow from S1 to S14 is omitted, and the control flow from S15 described later is executed. In the subsequent period, the number of failure occurrences is predicted. Specifically, the control unit 1 monitors whether or not the acquisition timing has arrived (S15). When the acquisition timing has arrived (Y in S15), after acquiring the acquired set data (S16), a predetermined period from the present time The number of failure occurrences until the elapsed time is obtained based on a prediction formula or the like (S17). If the predicted value of the number of failure occurrences is “1” abnormality (Y in S18), the failure prediction value (predicted value of the number of failure occurrences) is notified (S19). This notification is performed by display on the operation display unit 3. In addition, you may make it alert | report a predicted value irrespective of the predicted value of a failure occurrence number.

Next, the normal group data group construction process during the first period will be described in detail. In this copying machine, for example, acquired set data composed of 33 types of data shown in Table 1 below is acquired, for example, every p printouts (acquisition timing is reached).

Hereinafter, the type number in Table 1 will be described as a variable “j”. In addition, data is represented by x, and j is added as a subscript to represent the type of data. For example, if x _{j = 1} , this represents temperature data. If the value of p is too small, a large amount of data storage capacity and processing time are required. On the other hand, if it is too large, the prediction accuracy is lowered due to the lack of the number of acquired data. For this reason, it is desirable that the value of p is appropriately set in consideration of them.

  As will be described in detail later, the control unit 1 of this copying machine goes back by the predetermined number of acquisitions from the time of acquiring the acquired set data or passes the time by the predetermined number of acquisitions as necessary. Assuming this future, various types of arithmetic processing are performed. Hereinafter, the acquisition time point of the acquired set data is represented by α (acquired acquisition of the acquired set data), and the above-described predetermined acquisition count is described as step q.

The control unit 1 acquires the first acquired set data ( _{xj = 1 to 33} ) from the time when the copier starts to be used by the user to when the p-th printout is first made. . Thereafter, the process of S4 in FIG. 5 is omitted until the first to (q−1) th acquired set data is acquired. Then, after acquiring the qth acquired set data, the process of S4 in FIG. 5 is performed. In this step, normal set data is constructed as follows.

That is, first, each of the 33 types of data in the latest α-th acquired set data is incorporated into the normal set data as one of the data. Hereinafter, these latest data are represented as _xja . This _xja is mathematically expressed as follows.

Next, for each of the 33 types of latest data, the slope x _jb of the fluctuation of the value up to the α-th from the time point that is earlier than the α-th by the q-th (α-q-th) is obtained as follows. In the normal group data. Note that T in the following expression represents a difference in cumulative acquisition numbers from the latest acquisition number α (hereinafter referred to as an acquisition number difference). Further, Σ represents the sum (1 to q) of numbers related to the acquisition number difference T.

Further, the control unit 1 determines the coefficient of variation (standard deviation as an average value) of the values up to the α-th from the time point that is the q-th backward from the α-th for the 33 types of latest data. (Division) x _jc is _obtained as shown in the following equation and incorporated in the normal set data. In the following equation, σ _j (α) represents the standard deviation of x _j in step q. X _jav (α) represents the average value of x _j in step q.

  By constructing normal group data in this way, the number of data types becomes three times the number of data types in the acquired group data (33 × 3 = 99 types).

After the start of the initial operation, the first normal set data constructed first is a combination of the following data.
The latest acquired set data x _{j (= 1 to 33) a} (α = q)
The first to qth gradient data x _{j (= 1 to 33) b} (α = q) for each acquired data (one data in the acquired set data)
The first to qth variation coefficient data x _{j (= 1 to 33) c} (α = q) for each acquired data

The second normal set data is a combination of the following data.
The latest α (= q + 1) -th acquired set data x _{j (= 1 to 33) a} (α = q + 1)
The gradient data x _{j (= 1 to 33) b} (α = q + 1) from the second to the α (= q + 1) th for each acquired data (one data in the acquired set data)
The second to α (q + 1) th variation coefficient data x _{j (= 1 to 33) c} (α = q + 1) for each acquired data

The third normal set data is a combination of the following data.
The latest α (= q + 2) -th acquired set data x _{j (= 1 to 33) a} (α = q + 2)
The gradient data x _{j (= 1 to 33) b} (α = q + 2) from the third to the α (= q + 2) th for each acquired data (one data in the acquired set data)
The third to α (q + 2) th variation coefficient data x _{j (= 1 to 33) c} (α = q + 2) for each acquired data

  In this way, normal group data is sequentially constructed for every p printouts. This is repeated until the first period ends, for example, until 20000 printouts are completed.

Hereinafter, the normal set data is represented as y _{j (= 1 to 99)} for the purpose of distinguishing it from the acquired set data.

Next, a process for acquiring data for constructing a prediction formula during the second period described above and a process for constructing a prediction formula thereafter will be described in detail.
During the second period, the latest acquisition data, slope data, and coefficient of variation data at each acquisition time point (α) are constructed in the same manner as the normal set data group, and these are set as the normal set data group. Is stored in a separate data table. Further, as shown in S10 of FIG. 5, it is determined whether or not a failure has occurred at each acquisition time point (α). If there is a failure, the number of occurrences associated with the acquisition time point (α) is stored in the data table. To remember. An example of this data table is shown in Table 2 below. In Table 2, M represents the number of failures. K represents a data type number (k = 1 to 99).

When such a data table (hereinafter referred to as a prediction formula construction data table) is constructed and the second period has elapsed, the control unit 1 constructs a prediction formula. The outline of the construction method of the prediction formula is as follows. That is, for each set data (data of y _{k = 1 to 99} excluding M) in the prediction formula construction data table, multivariate analysis is performed using the normal set data group that has been constructed previously, An abnormality determination index value D indicating normality is obtained. As the multivariate analysis, any analysis method may be used, but the following description will be made by taking two methods as examples.

First, the MTS method will be described as a first example of multivariate analysis.
Table 3 below shows a data table of a normal group data group. Note that the set number (i) in Table 3 indicates what number of normal set data is constructed.

When the MTS method is used, a normalized data table as shown in the following Table 4 is constructed based on this normal set data group.

Data normalization is a process for converting absolute value information into variable information for various types of data. Normalized data for various types of information is calculated based on the following relational expressions. Note that i in the following expression is a code indicating any one of the n sets of group data. Further, j is a code indicating that it is any one of k types of information.

Once the normalized data table is constructed, the correlation coefficient between each data is calculated next. In this process, among the n sets of normalized data, the correlation coefficient r is calculated based on the following equation for all combinations ( _k C ₂ types) in which two different types of k types of normalized data can be established. _pq (r _qp ) is calculated.

Once the correlation coefficients r _pq (r _qp ) have been calculated for all combinations, then k × k phases, with the diagonal element being 1 and the other elements in p rows and q columns being correlation coefficients r _pq A relational number matrix R is constructed. The contents of this correlation coefficient matrix R are shown in the following equation.

Once such a correlation coefficient matrix R is constructed, an inverse matrix A = (R ⁻¹ ) represented by the following equation is constructed.

Treating this inverse matrix A as a normal group data group, the Mahalanobis distance (md) as an abnormality determination index value for each group data in the prediction formula construction data table previously shown in Table 2 is based on the following formula: Ask. Incidentally, in the formula, X _p after the above numbers 1, number 2, one of the processing number 3 is applied, it shows a similar process as the number 4 has been performed the data.

  FIG. 6 is a flowchart showing a series of processes until the normal set data group is converted into the inverse matrix A. In the figure, when a normal group data group is constructed (S1-1), an average value and a standard deviation σ based on the above-described relational expression 4 are calculated for each information type (j). A normalized data table is constructed based on the result (S1-2). Then, after the correlation coefficient matrix R is constructed based on the normalized data table (S1-3), it is converted into an inverse matrix A (S1-4).

FIG. 7 is a flowchart showing a procedure for calculating the Mahalanobis distance (md) based on the inverse matrix A and various types of acquired data. In this procedure, firstly, k type of data _x 1 in any _state, x 2 · · ·, x _k is obtained (S2-1). The data types correspond to y ₁₁ , y ₁₂ ,..., Y _{1k and the} like. Next, each acquired data is normalized to X ₁ , X ₂ ,..., X _k based on the relational expression ( ₁ ). Then, the square of the Mahalanobis distance (md) is calculated by the relational expression of Equation 8 determined using the element a _kk of the inverse matrix A that has already been constructed. “Σ” in the figure represents the sum of the subscripts p and q.

  The Mahalanobis distance (md) thus determined is used as the abnormality determination index value D.

Next, a second example of multivariate analysis will be described.
In this second example, the normal set data group shown in Table 3 and the state evaluation value at that time are standardized by obtaining the difference from the average value based on the following two relational expressions. Note that the overbar “に お け る” in the following equation indicates the average value of data in the normal group data group.

The data table after standardization is shown in Table 5 below.

Next, the α-th acquired data x _j (α) in the prediction formula construction data table previously shown in Table 2 and the state evaluation value M ′ (α) corresponding thereto are represented by the following two relational expressions. Similarly, based on the above, it is related to the previous solution of Equation 9 and the solution of Equation 10.

Then, β _j and η _j are obtained from the following five relational expressions (Σ represents a sum related to α in the prediction formula construction data table).

Next, an abnormality determination index value D is obtained based on the following equation.

After obtaining the abnormality determination index value D for each set of data in the prediction formula construction data table by multivariate analysis as in the first example and the second example, next, each abnormality determination index value D _{i (= 1 to n)} and the number of failures M _{i (= 1 to n)} (M ₁ , M ₂ ... M _n in Table 2) are proportional to each other. The coefficient β ₀ is calculated based on the following equation.

Next, using the slope coefficient β ₀ , the following prediction formula for determining the predicted value <M> of the number of failure occurrences at a future time point when step q has elapsed from the data acquisition time point α is constructed.

  The control unit 1 that has constructed the prediction formula after the above-described second period elapses acquires acquired set data for every p printouts as shown in S15 to S20 of FIG. Then, the abnormality determination index value D is obtained based on the acquired set data and the normal set data group stored in the hard disk. Next, based on the abnormality determination index value D and the prediction formula shown in Expression 20, a predicted value <M> of the number of failure occurrences from the current time until (p × step q) printouts are obtained. Then, the predicted value <M> is displayed on the operation display unit 3.

  In addition, although the example which employ | adopted every p sheet printout was demonstrated as an acquisition timing of acquisition set data, you may employ | adopt the timing for every predetermined time progress. Further, the determination result of the presence / absence of abnormality and the predicted value <M> may be transmitted to the maintenance service organization via a communication line such as a telephone line.

Next, a description will be given of the copying machine of each example in which a more characteristic configuration is added to the copying machine according to the embodiment.
[First embodiment]
In the copying machine according to the embodiment, the predicted value <M> of the number of failure occurrences from the current time point (α) at which the latest acquired set data is acquired to a future time point at which p printouts are performed thereafter is obtained. In such a configuration, for example, even when the predicted value <M> is “0”, that is, when no abnormality is detected, “the remaining p sheets can be printed out normally”. Can be displayed on the operation display unit 3 to give the user a sense of security. For example, when the predicted value <M> is “1.2”, that is, when an abnormality is detected, “one or two abnormal images are output before another p printouts are output. "There is a risk that one or two fatal paper jams will occur before printing another p.", "Until p. It is expected that there will be one or two troubles of unknown cause. Please contact a service person. ”On the operation display unit 3 to inform the user of the margin until the trouble occurs. be able to.

  However, it may be difficult for a user to grasp how long it is during the period until “printing out another p sheets”. Therefore, in the copier according to the first embodiment, the control unit 1 is configured to perform the following control. That is, instead of the timing of every p sheets, the timing of every elapse of p time is adopted as the above acquisition timing. At such an acquisition timing, the predicted value <M> is obtained as the number of failure occurrences in “until the remaining p × q time”. Therefore, the control unit 1 is configured to calculate the average operating time per day while measuring the cumulative operating time of the image forming unit, and to perform control for dividing p × q time by the calculation result. In such a configuration, by letting the number of days until the failure occurs, such as “before how many days have passed”, the user can accurately grasp the margin until the failure occurs.

[Second Embodiment]
In the copying machine according to the second embodiment, the control unit 1 is configured to perform the following control. The control unit 1 is configured to calculate the average number of prints per day while counting the cumulative number of printouts of the image forming means, and to perform control for dividing p × q sheets by the calculation result. Even in such a configuration, it is possible to allow the user to accurately grasp the degree of margin until the failure occurs by notifying the number of days until the failure occurs, such as “by how many days later”.

  Next, a modified apparatus of the copying machine according to the embodiment will be described. This modified apparatus is different from the copying machine according to the embodiment in that the construction of the normal group data group and the construction of the prediction formula are performed during the same period. Specifically, during the first period from the start of the initial operation until a predetermined time elapses, the acquired set data is acquired at each predetermined acquisition timing and sequentially stored in the temporary data table. At this time, if the occurrence of a failure is detected or information indicating that a failure has occurred is input to the operation display unit 3, the information acquired from the time point up to step q from that point in time is acquired. The acquired set data is moved from the temporary data table to the above-described prediction formula construction data table. At the same time, data on the number of occurrences of failures is input to the prediction formula construction data table. When the first period elapses, a normal group data group is constructed based on the temporary data table. Further, a prediction formula for the number of failure occurrences is constructed based on the prediction formula construction data table.

  When the normal group data group and the prediction formula are constructed in this way, the number of failure occurrences is predicted based on the acquired group data and the prediction formula during the second period thereafter.

As described above, in the copying machine according to the embodiment, as normal set data, in addition to a plurality of types of acquired data and a plurality of _pieces of inclination data (X _jb (α)) individually corresponding thereto, Data including the coefficient of variation data (X _jc (α)) from the time point that is a predetermined number of times before the acquisition time point to the acquisition time point α is stored in the hard disk as data storage means. Each acquisition set data is acquired based on the latest acquired set data (X _jb (α)) acquired by the control unit 1 as data acquisition means and the past acquired set data stored in the hard disk. Inclination data and variation coefficient data are calculated for each piece of data. Further, the abnormality determination index value D is calculated based on the calculation result, the latest acquired set data, and the normal set data group. In such a configuration, the predicted value <M> of the number of occurrences of abnormality can be predicted more accurately as compared to the case where only the slope data is included as data other than the acquired set data included in the normal set data group.

In the copying machine according to the embodiment, the control unit 1 is functioned as a counting unit that counts the number of failures. Then, the normal set data group is constructed based on the acquired set data acquired during the predetermined first period, and the acquired set data acquired during the subsequent second period and the failure counted by the control unit 1 The slope coefficient β ₀ is calculated based on the number of occurrences, and the acquired set data acquired after the second period, which is the third period thereafter, the slope data based on this, and the normal set data group The predicted value <M> is obtained by multiplying the abnormality determination index value D calculated in this way by a predetermined coefficient (1 / slope coefficient β ₀ ). In such a configuration, it is possible to automatically perform the construction of the normal group data group, the construction of the subsequent prediction formula, and the subsequent abnormality determination and prediction of the predicted value.

Further, in the modified apparatus, the control unit 1 is made to function as counting means for counting the number of failure occurrences. Then, the normal set data group is constructed based on the acquired set data acquired by the data acquisition means during the predetermined first period, and the slope coefficient is calculated based on the acquired set data and the number of failure occurrences counted by the control unit 1. is computed the beta _0, and the subsequent and the acquired group data acquired by the data acquisition means during the second period, and the slope data based on this, the abnormality determination index value D calculated based on the normal group data set Is multiplied by a predetermined coefficient (1 / slope coefficient β ₀ ) to obtain the predicted value <M>. Even in such a configuration, it is possible to automatically perform the construction of the normal group data group, the construction of the subsequent prediction formula, and the subsequent abnormality determination and prediction of the predicted value.

  Further, in the copying machine according to the first embodiment, data for a predetermined number of times (step q) from the time (α) when the latest acquired set data is acquired based on the average operating time per day of the image forming means. The control unit 1 is made to function as a correction unit that corrects a period until a future time point at which acquisition is performed. Then, the combination of the control unit 1 and the operation display unit 3 is made to function as a notification unit so as to notify the predicted value <M> as a predicted value of the number of failures occurring in the corrected period. In such a configuration, the predicted value <M> is acquired for the user as compared with a case where the predicted value <M> is simply notified to the user as a predicted value of the number of failure occurrences in the period from the acquisition time point (α) until step q elapses. It is possible to grasp the degree of margin from the time (α) to the occurrence of a failure more accurately.

  In the copying machine according to the second embodiment, the latest acquisition group data is acquired based on the daily average number of printed sheets, which is the average number of recording members output per day of the image forming means (α). The control unit 1 is made to function as a correction unit that corrects a period from when the data is acquired a predetermined number of times (step q) to a future time point. And the combination of the control part 1 and the operation display part 3 is made to function as an alerting | reporting means which alert | reports predicted value <M> as a predicted value of the occurrence number of failures in the period after correction | amendment. Even in such a configuration, compared to a case where the predicted value <M> is simply notified to the user as a predicted value of the number of occurrences of failures in the period from the acquisition time point (α) to the step q, It is possible to grasp the degree of margin from the acquisition time (α) to the occurrence of a failure more accurately.

1 is a schematic configuration diagram showing a copier according to an embodiment. FIG. 2 is a schematic configuration diagram illustrating a printer unit of the copier. The elements on larger scale which show the tandem part of the copier. FIG. 2 is a block diagram showing a part of an electric circuit of the copier. 6 is a flowchart showing a processing flow in long-term control performed over a relatively long period by the control unit of the copier. The flowchart which shows a series of processes until it converts a normal group data group into an inverse matrix. The flowchart which shows the procedure which calculates Mahalanobis distance based on an inverse matrix and various acquisition data.

Explanation of symbols

1: Control unit (part of data acquisition means, part of notification means, index value calculation means, data storage means, storage control means, counting means, correction means)
2: Various sensors (part of data acquisition means)
3: Operation display section (part of data acquisition means, part of notification means)
100: Printer section (part of image forming means)
200: paper feed unit (part of image forming means)

Claims (6)

Image forming means for forming an image on a recording member, data acquisition means for acquiring a plurality of types of data from the image forming means, and normal set data that is a collection of normal set data including the plurality of types of data having normal values. An abnormality determination index value is calculated based on data storage means for storing a group, acquired set data composed of a plurality of types of data acquired by the data acquisition means, and normal set data groups stored in the data storage means In an image forming apparatus comprising an index value calculation means for
A storage control means for sequentially storing the acquired set data acquired by the data acquisition means in the data storage means every time a predetermined timing arrives;
As the normal set data, in addition to the plurality of types of data, each of the data includes slope data of a change in value from the time point acquired by a predetermined number of times before the acquisition time point to the acquisition time point. What is included is stored in the data storage means,
Each of the plurality of types of data in the acquired set data is based on the latest acquired set data acquired by the data acquiring unit and the past acquired set data stored in the data storage unit. The index value calculation means is configured to calculate the abnormality determination index value based on the calculation result, the latest acquired set data, and the normal set data group after calculating the tilt data for An image forming apparatus. The image forming apparatus according to claim 1.
As the normal group data, in addition to the plurality of types of data and the plurality of inclination data individually corresponding thereto, each of the plurality of types of data is traced back by a predetermined number of acquisition times before the acquisition time point. Storing the coefficient of variation data from the time point to the acquisition time point in the data storage means,
Each of the plurality of types of data in the acquired set data is based on the latest acquired set data acquired by the data acquiring unit and the past acquired set data stored in the data storage unit. The index value calculation is configured to calculate the abnormality determination index value based on the calculation result, the latest acquired set data, and the normal set data group after calculating the slope data and variation coefficient data for An image forming apparatus. The image forming apparatus according to claim 1 or 2,
Provide a counting means to count the number of failure occurrences,
The acquired set data acquired by the data acquisition unit during the second period after the normal set data group is constructed based on the acquired set data acquired by the data acquisition unit during a predetermined first period. And a predetermined coefficient based on the number of failure occurrences counted by the counting means, and the acquired set data acquired by the data acquiring means during the subsequent third period, and the above based on this By multiplying the abnormality determination index value calculated based on the inclination data and the normal group data group by the predetermined coefficient, the predetermined number of times of data acquisition is performed from the time when the latest acquired group data is acquired. An image forming apparatus characterized in that a predicted value of the number of occurrences of failures up to a future time point is obtained. The image forming apparatus according to claim 1 or 2,
Provide a counting means to count the number of failure occurrences,
The normal set data group is constructed based on the acquired set data acquired by the data acquisition means during a predetermined first period, and based on the acquired set data and the number of failure occurrences counted by the counting means. And calculating based on the acquired set data acquired by the data acquisition means during the subsequent second period, the inclination data based on the acquired set data, and the normal set data group By multiplying the abnormality determination index value by the predetermined coefficient, a predicted value of the number of failure occurrences from the time when the latest acquired set data is acquired to the future time when the data acquisition for the predetermined number of times is obtained. An image forming apparatus characterized by being configured as described above. The image forming apparatus according to claim 3 or 4,
Based on the average operating time per day of the image forming means, there is provided a correcting means for correcting a period from the time when the latest acquired set data is acquired to a future time point when the predetermined number of data acquisition is performed. An image forming apparatus comprising an informing means for informing the number of occurrences as a predicted value of the number of occurrences of failures in the corrected period. The image forming apparatus according to claim 3 or 4,
Correction means for correcting a period from the time when the latest acquired set data is acquired to the future time point when the predetermined number of times of data acquisition is performed, based on the average number of recording member outputs per day of the image forming means And an informing means for informing the number of occurrences as a predicted value of the number of occurrences of failures in the corrected period.

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