JP2013025196A - Failure diagnosis method, failure diagnosis device, and image forming device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a failure diagnosis method and a failure diagnosis device capable of specifying a cause of a fixing failure.SOLUTION: A sheet is separated and conveyed by a noncontact separation plate 51 divided into a plurality of pieces to be arranged at the nip exit of a fixing device 5 for applying heat and pressure to the sheet. A heating member used for smoothing the toner surface layer of the sheet is held on the downstream side of the fixing device 5. Glossiness is increased by a gloss application device 6 which includes a temperature-controlled rotor 80 and a rotor 90 pressed into contact with or separated from the rotor 80. The failure diagnosis of a cause of a failure of the fixing device 5, including estimation of the failure cause, is carried out by three means, i.e., means for storing the number of paper jamming times in the fixing device 5, means for storing a current value of a contact/separation motor, and means for storing the position of the leading end of the pressure separation plate 51 of the pressure roller 14 side.

Description

  The present invention relates to a failure diagnosis method for maintaining a good operating state in an image forming apparatus such as an electrophotographic copying machine, printer, facsimile, or a multifunction machine thereof, the same apparatus, and an image forming apparatus using the same. About.

  The image forming apparatus is composed of many units and parts. When an abnormality occurs in the image forming apparatus due to these failures or lifetimes, it is necessary to perform repairs and maintenance such as replacement of units or parts. It is necessary to stop some or all of the functions of the image forming apparatus during maintenance after an abnormality occurs and during maintenance before the abnormality occurs.

  It may take a long time to determine the cause of this abnormality, and there is an inconvenience that the user cannot use the image forming apparatus during this time. Therefore, it is desired to reduce and reduce downtime by diagnosing where an abnormality of the image forming apparatus occurs or by performing maintenance.

  As a method for estimating a failure location, a technique is known in which a failure location is estimated by fuzzy inference using an information amount indicating the use state of the apparatus, and the time required for repair is reduced from the occurrence of the failure (see Patent Document 1). . In this technology, the mixing ratio (absolute humidity) is obtained from the temperature and humidity, and is used as one of the information amounts together with the separation difference current output value and the separation difference current adjustment value, and the separation difference current adjustment failure, separation charger failure, Estimate the rate of transfer material failure.

  Also, using the Bayesian network to identify the failure establishment of the node from the operation state feature quantity and the paper transport time feature quantity, and based on the failure establishment, the candidate for the location that may or may cause the failure is identified. An extraction technique (see Patent Document 2) is also known.

  We also know technologies for calculating comprehensive index values in consideration of operation control information for multiple types of equipment, determining the presence or absence of abnormal equipment conditions based on the index values, and predicting the occurrence of equipment failures. (See Patent Document 3).

  Problems and failures related to the fixing unit may cause various causes and cause a long maintenance time, and unnecessary maintenance may occur at a location different from the cause.

  Therefore, in the present invention, a failure diagnosis method that can identify the cause of fixing failure is provided, a failure diagnosis device that can reduce or reduce downtime due to various events as described above, and the like. An object of the present invention is to provide an image forming apparatus.

  According to another aspect of the present invention, there is provided a failure diagnosis method comprising: a fixing device that applies heat and pressure to a sheet onto which an image-formed unfixed toner has been transferred by a heating roller and a pressure roller; A method for diagnosing the cause, wherein the number of occurrences of paper jams occurring in the fixing device is stored, the current value of the contact / separation motor of the fixing device is stored, and the pressure roller side of the fixing device is stored. The tip position of the pressure separation plate is stored, the three stored data are used for weighting by the boosting method, and the failure of the equipment constituting the image forming apparatus including the estimation of the cause of the failure in the fixing device is detected. It is characterized by making a diagnosis.

  The failure diagnosis apparatus according to the present invention is an image forming apparatus including a fixing device that applies heat and pressure to a sheet onto which image-formed unfixed toner has been transferred with a heating roller and a pressure roller. An apparatus for diagnosing the cause of failure, the means for storing the number of occurrences of paper jam occurring in the fixing device, the means for storing the current value of the contact / separation motor of the fixing device, and the pressure roller of the fixing device Means for storing the position of the tip of the pressure separation plate on the side, means for weighting the data stored by the three means, and whether each data is normal based on the result of weighting by the means for weighting And a means for discriminating whether there is an abnormality, and diagnosing a failure of an apparatus constituting the image forming apparatus including an estimation of a cause of the failure in the fixing device.

  An image forming apparatus according to the present invention includes the failure diagnosis apparatus.

  According to the present invention, the cause of a failure in the fixing device can be specified, and downtime due to various events that cause such a failure can be reduced or reduced.

Schematic sectional view showing an example of a color image forming apparatus Schematic sectional view showing the fixing unit The figure which shows the fixing device contact / separation motor current waveform The figure which shows the fixing device contact / separation motor current value Diagram showing pressure separation plate tip position fluctuation Diagram showing feature value time series data (contact / separation motor drive current effective value) Figure showing feature time series data (number of paper jams) Diagram showing feature time series data (FR deviation of tip position of separator) The figure which shows F value change with time

  Hereinafter, embodiments according to the present invention will be described with reference to the drawings.

<Configuration of image forming apparatus>
FIG. 1 is a schematic sectional view of a digital color copying machine apparatus (hereinafter simply referred to as a color copying machine) as an example of an image forming apparatus according to the present invention. The color copying machine 100 includes an image reading unit 100A located at the upper part of the apparatus main body, an image forming part 100B located at the central part of the apparatus main body, and a paper feeding unit 100C located at the lower part of the apparatus main body. The image reading unit 100A includes a scanner unit 1 that optically reads image information of a document, and an ADF (automatic document feeder) 10 that continuously conveys the document to the scanner unit 1.

  In the image forming unit 100B, a belt-like intermediate transfer body 30 having a transfer surface extending in the horizontal direction is disposed as an intermediate transfer unit. On the upper surface of the intermediate transfer member 30, a configuration for forming an image having a color complementary to the color separation color is provided. That is, four photoconductors 31 as image carriers that are means capable of carrying an image of toners of complementary colors (yellow, magenta, cyan, black) are arranged along the transfer surface of the intermediate transfer member 30. ing.

  A writing unit 2 that irradiates the peripheral surface of each photoconductor 31 with exposure light based on the scanner image information and external image information is disposed above the photoconductor 31. Each photoconductor 31 is composed of a drum that can rotate in the same direction (counterclockwise direction). Around the photosensitive member 3, a developing unit 3 including a charging device, a developing device, and a primary transfer device that perform image forming processing in a rotating process, and a cleaning unit 36 that collects residual toner on the photosensitive member 31 after transfer. Is arranged. Each developing device contains respective color toners.

  The intermediate transfer member 30 is configured to be able to move in the same direction at a position facing each photoconductor 31 by being wound around a driving roller and a driven roller. A secondary transfer portion 34 as a transfer roller is provided at a position facing one of the driven rollers. Further, on the sheet conveyance path line from the position of the secondary transfer unit 34, there are a conveyance belt 35, a first fixing unit, a fixing device 5 for fixing an image by heating and pressing, and a second fixing unit. The gloss imparting device 6 used for smoothing the toner surface surface layer by heating and the transport roller pair 7 for transporting the paper that has passed through the gloss imparting device 6 are arranged in this order.

  The paper feed unit 100C includes a plurality of paper feed trays 41a, 41b, 41c, and 41d (hereinafter simply referred to as a paper feed tray 41 unless otherwise required) for stacking and storing sheets as recording media. A transport mechanism including a transport path 37 that transports the sheets in the sheet 41 one by one from the top one to the position of the secondary transfer unit 34, and a registration unit 38 that performs image formation timing and skew correction. Have. The number of paper feed trays is not limited to the illustrated example.

Image formation in the color copying machine 100 of this example will be described.
First, the surface of the photoconductor 31 is uniformly charged by the charging device of the developing unit 3, and the color is applied to each photoconductor 31 by the writing unit 2 based on the scanner image information from the image reading unit 100 </ b> A or external image information. An electrostatic latent image corresponding to the above is formed. The formed electrostatic latent image is visualized as a toner image by a developing device containing toner of the corresponding color, and this toner image is formed on the intermediate transfer member 30 by a primary transfer device to which a predetermined bias is applied. Primary transfer. As a result, the toner images of the respective colors are sequentially transferred and superimposed on the intermediate transfer body 30 by electrostatic force.

  The toner image primarily transferred onto the intermediate transfer member 30 is transferred to the sheet conveyed by the secondary transfer unit 34. The sheet onto which the toner image has been transferred is further conveyed to the fixing device 5 and is fixed at the fixing nip portion between the fixing member and the pressure member. Next, the fixing toner on the paper is glossed by the glossing device 6 as necessary, transported by the transport roller pair 7, and sent out from the paper discharge unit 8 along the discharge path, as an output image. A series of image forming processes are completed by discharging from the apparatus main body.

  As shown in FIG. 2, the fixing device 5 includes a fixing belt 11 that is an example of an endless belt.

  The fixing belt 11 is wound around four rollers, a fixing roller 12 having an elastic layer, a heating roller 15, a separation roller 13, and a tension roller 16. The endless belt can be wound around three or more rollers. A pressure roller 14, which is an example of a pressure member, is in pressure contact with the surface of the fixing belt 11 (a pressure belt or the like can be used as the pressure member).

  In the illustrated example, the pressure roller 14 is in pressure contact with the fixing belt 11 from the portion of the fixing belt wound around the fixing roller 12 to the portion of the fixing belt wound around the separation roller 13 to form a first nip N1. Yes.

  The pressure roller 14 is rotationally driven in the direction of arrow A in FIG. 2 by a motor (not shown). The rotation is transmitted to the fixing roller 12 and the separation roller 13 through a gear (not shown), whereby the fixing roller 12 is rotationally driven in the direction of arrow B in FIG. Further, the fixing belt 11 is driven to run in the direction of arrow D by the rotation of the fixing roller 12, whereby the heating roller 15 is driven to rotate in the direction of arrow C.

  The heating roller 15 is formed in a hollow shape, and a heater 15h is disposed in each of the heating rollers 15. The heating roller 15 and the fixing belt 11 are heated by the heater 15h, respectively. Alternatively, the pressure roller 14 and the fixing roller 12 may be formed in a hollow shaft shape, and a heater may be additionally disposed therein so that each roller can be heated.

  Further, a temperature sensor (not shown) is opposed to the fixing belt portion that contacts the heating roller 15, the fixing belt portion that contacts the fixing roller 12, and the pressure roller 14. Based on the temperature detection results by these sensors, the energization of each heater described above is controlled, and the temperature of the fixing belt 11 and the pressure roller 14 is controlled to be a temperature suitable for fixing the toner layer.

  The fixing belt 11 includes, for example, a base material made of polyimide, a silicone rubber provided on the base material, and a surface layer made of a fluororesin laminated on the surface of the silicone rubber.

  The fixing device 5 may be configured by a roller pair.

  A separation plate 50 that separates the recording medium holding the toner layer from the fixing belt 11 is provided downstream of the first nip N1 in the recording medium conveyance direction. The separating plate 50 is divided into a plurality of parts in the main scanning direction, and the leading end position of each separating plate 50 is a position away from the fixing belt 11 by a specified amount (a position where the separated distance forms a specified amount of gap: The same shall apply hereinafter). As for the gap between the separation plate 50 and the fixing belt 11, abutting members that contact the fixing belt 11 in the non-sheet passing region are disposed at both ends of the stay material that holds the separation plate 50, and the abutting member is fixed with a specified force. While being in contact with the belt 11, the distance between the separation plate 50 and the fixing belt 11 is measured and adjusted to a specified amount. As a result, the thickness of the recording medium is thin, and even if the toner layer on the recording medium is near the front end in the conveying direction of the recording medium, it can be reliably conveyed.

  The fixing device 5 also includes a pressure separation plate 51 on the pressure roller 14 side that is located downstream of the first nip N1 in the recording medium conveyance direction. The pressure separation plate 51 is also divided into a plurality of parts in the main scanning direction, and the tip position of each pressure separation plate 51 is adjusted to a position away from the pressure roller 14 by a specified amount. The gap between the pressure separation plate 51 and the pressure roller 14 is arranged such that an abutting member that contacts the pressure roller 14 in the non-sheet passing region is disposed at both ends of the stay material that holds the pressure separation plate 51, and the specified force In the state where the abutting member is brought into contact with the pressure roller 14, the distance between the pressure separation plate 51 and the pressure roller 14 is measured and adjusted to a specified amount. As a result, the thickness of the recording medium is thin, and the recording medium can be reliably transported even when the toner layer on the pressure roller 14 side on the recording medium is close to the front end of the recording medium.

  The gloss applying device 2 shown in FIG. 2 includes a roller 80 and a roller 90, and at least one of the roller 80 and the roller 90 is provided with an elastic layer and a surface property control layer that forms a surface layer. The second nip N2 is formed by pressing the rollers 80 and 90 together. At least one of the two rollers 80 and 90 is formed in a hollow shape, and a heater 85 is disposed therein, and the rollers 80 and 90 are heated by the heater 85. Although not shown, a temperature sensor is disposed opposite to the roller 80 or 90 in which a heater is disposed inside, and the energization to the heater 85 is controlled based on the temperature detection result by the temperature sensor, and the temperature of the rollers 80 and 90 is determined. Is controlled to become the set temperature.

  The surface temperature of the roller 80 is controlled so as to appropriately gloss the fixing toner in the mode for imparting gloss to the image. For example, the surface temperature of the roller 80 that contacts the fixing toner on the recording medium is lower than the surface temperature of the fixing member (fixing belt 11) of the fixing device 5. Alternatively, the surface temperature of the roller 80 is preferably not less than the recording medium temperature when the recording medium enters the gloss applying device 6 and not more than the recording medium temperature immediately after the recording medium is discharged from the fixing device 5.

  The surface temperature of the roller 80 is preferably not less than the softening temperature of the toner used by the flow tester and not more than ½ outflow start temperature, more preferably not less than the softening temperature and not more than the outflow start temperature. Here, the physical property temperatures of these toners are, for example, using a flow tester (CFT-500D (manufactured by Shimadzu Corporation)), a load of 5 kg / cm 2, a heating rate of 3.0 ° C./min, a die diameter of 1. It is good to measure on condition of 00mm and die length 10.0mm, and to obtain | require from the relationship of the piston stroke with respect to temperature. The 1/2 outflow start temperature is a temperature that is the midpoint between the outflow start temperature and the outflow end temperature. “^” Indicates a power.

  Specifically, the surface temperature of the roller 80 is preferably 60 ° C. (softening temperature at the physical property temperature of the used toner) to 137 ° C. (1/2 outflow start temperature at the physical property temperature of the used toner), and preferably 60 to 120 ° C. (used toner). The outflow start temperature at the physical property temperature is preferably 80 to 100 ° C. The temperature related to the toner (toner physical property temperature) varies depending on the toner lot and color, and the temperature shown here is an average value.

  After the unfixed toner layer on the recording medium is fixed to the recording medium at the first nip N1, the recording medium and the fixing toner layer are placed in the second nip N2 while maintaining the state where the toner layer can be deformed by an external force. The surface of the toner layer is solidified by simultaneously transferring the surface of the rollers 80 and 90 to the surface of the toner layer by controlling the surface property of the toner layer. For example, a high gloss image can be obtained by setting the surfaces of the rollers 80 and 90 as mirror surfaces, and conversely, low gloss can be obtained by setting the surfaces of the rollers 80 and 90 rough. Here, the gloss applying device 6 may have a belt fixing configuration.

  The front end position of the separating plate 50 described above is adjusted in a state where the abutting member in contact with the fixing belt 11 bites into the fixing belt 11 or the fixing roller 12 inside the fixing belt 11. For this reason, when the rubber hardness or the rubber repulsive force of the fixing roller 12 having a large change with time changes, the position changes from the initially adjusted position. That is, the gap between the separation plate 50 and the fixing belt 11 varies with time.

  In order to monitor the rubber hardness of the fixing roller 12 or the fluctuation of the rubber repulsive force, the load current value of the contact / separation motor (not shown) that performs the pressure contact operation for forming the nip is optimal. In addition, if the gap between the separation plate 50 and the fixing belt 11 fluctuates, a paper jam is likely to occur. Therefore, the frequency of paper jam is an effective means for grasping the situation. Further, the fluctuation of the rubber hardness or the rubber repulsive force of the fixing roller 12 does not fluctuate uniformly in both the main scanning direction and the circumferential direction, and has a fluctuation deviation, so that the main scanning direction (front side) at the position of the abutting member. F, back side; variation deviation may occur in R). In that case, depending on the amount of change, the contact state of the abutting member to the fixing belt 11 changes depending on F and R, and the gap between each of the plurality of separation plates 50 and the fixing belt 11 in the main scanning direction changes. .

  Therefore, by monitoring the position variation from the initial stage of each separation plate 50, for example, the variation deviation (FR deviation) between the F side and the R side is grasped, and the variation in the gap between the separation plate 50 and the fixing belt 11 is grasped. It becomes possible to do. In order to monitor the position variation from the initial stage of each separation plate 50, the output value of the distance measuring sensor 150 capable of detecting the change in the position of the separation plate 50 is optimal.

<Means for storing the number of occurrences of paper jams>
In the fixing device 5, paper jam occurs due to various causes.
Here, regardless of the cause of occurrence, the occurrence of a paper jam in the fixing device 5 is counted once and stored in a storage device that is not erased when the apparatus power is turned off. The number of occurrences is reset when the fixing roller 12 is replaced.

<Method for Collecting Contact / Separation Motor Current Value of Fixing Device 5>
The fixing device 5 of the image forming apparatus of this example includes a contact / separation drive motor. The contact / separation drive motor is disposed at a position opposite to the fixing roller 12 used to apply heat and pressure to the sheet onto which the unfixed toner image formed by the fixing device 5 is transferred, and to fix the toner to the sheet. This is a motor that enables the pressure roller 14 to be pressed against and separated from the fixing roller 12 via the fixing belt 11, and the pressure-separation operation is performed via a lever member 76 that holds the pressure roller 14. This is realized by the rotation of the cam 78. Further, the operation control of the contact / separation drive motor is implemented by a detection value of an optical sensor (not shown) that detects the specified position of the cam 78.

  FIG. 3 shows a contact / separation drive motor current waveform when the cam 78 is rotated once. The current waveform shown is the result of an example with a cam shape. As the cam rotates, the pressure roller 14 comes into pressure contact with the fixing roller 12, so that a repulsive force is generated and a moment is generated in the cam shaft. When the moment is generated, the on-axis torque increases, so that the current value of the contact / separation drive motor increases. Then, when passing the highest point of the cam, the repulsive force generated when the pressure roller 14 is brought into pressure contact with the fixing roller 12 is changed to a moment in the direction in which the cam shaft is rotated. The current value of the contact / separation drive motor decreases.

  This one-rotation operation of the cam is generally executed during the initialization operation or the recovery operation of the image forming apparatus. The recording timing of the contact / separation motor current value here is the integration of the fixing device 5 drive motor. You may record regularly for every regulation time of operation time.

<Calculation method of feature value of motor current value>
Based on the waveform obtained by excluding the rush current from the contact / separation drive motor current waveform during one cam rotation operation shown in Fig. 3, the square of the instantaneous value of the voltage or current that changes periodically is averaged over one cycle. The effective value expressed by the square root is taken as the second feature value. When the current waveform is an accurate sine wave, the effective value is equal to 1 / √2 of the peak value. Therefore, the peak value may be used as the second feature amount as long as they have the same cam shape.

  FIG. 4 shows the relationship between the nip surface pressure of the fixing device 5 and the contact / separation motor drive current effective value (second feature amount). A decrease in the nip surface pressure means a decrease in the repulsive force of the elastic layer in the fixing roller 12 having the elastic layer, and a decrease in the repulsive force means a decrease in motor torque during the contact / separation operation. . The numerical value and the gradient shown here are values under a specific condition, and change depending on the configuration of the roller.

<FR deviation sampling method for change in tip position of pressure separation plate 51 of fixing device 5>
FIG. 5 shows a method for calculating the FR deviation of the tip position fluctuation of the pressure separation plate 51.
The initial distance from the fixedly arranged distance measuring sensor 150 to the measurement position of the pressure separation plate 51 is Ls, and the distance of the pressure separation plate 51 on the F side when the position variation of the pressure separation plate 51 occurs is measured. The distance from the sensor 150 is Lf, and the R side is Lr.
The positional fluctuation amount of each pressure separation plate 51 is

The FR deviation amount of the pressure separation plate 51 tip position fluctuation is

Is calculated by
When this ΔG is increased, it can be determined that a large fluctuation has occurred in the gap between the pressure separation plate 51 and the pressure roller 14. Further, when a large fluctuation occurs in the gap between the pressure separation plate 51 and the pressure roller 14, the paper is likely to be caught on the pressure separation plate 51, and the occurrence frequency of paper jam increases when double-sided paper is passed. At that time, by controlling to increase and change the distance from the front end of the paper to the unfixed toner on the paper (front end margin amount), the paper is less likely to be caught by the pressure separation plate 51, and the occurrence frequency of the paper jam is reduced. Can be reduced.

<State discrimination method>
For the calculated feature quantities, weight values for contributing to fault diagnosis are calculated by a supervised learning algorithm called a boosting method.

The boosting method is described in detail in Non-Patent Document 1, but in summary,
First, for a data set consisting of multiple types of data, prepare a history from the normal state to the failure state,
For each history of various data, the failure period is estimated visually from the shape of the time variation graph,
A negative polarity label is attached to the data corresponding to the failure period,
On the other hand, the operation of attaching a positive polarity label to other data (data within a normal period) is repeated 100 times. Thus, threshold values b1 to b100, discrimination polarities sgn1 to sgn100, and weighting values α1 to α100 are determined for various data. Next, based on the feature quantities of various data, it is determined whether each data is normal or abnormal. Since this determination is not a decisive factor for failure prediction, the determination at this time is called weak determination processing.

  The stamp discriminator can perform CPU operations very quickly, and it uses a weighted majority vote to obtain sufficient accuracy, and it is a weak discriminator that is very suitable for realizing fault diagnosis technology with high accuracy and without cost. It is. The state discrimination calculation method when a stamp discriminator is used as the weak discriminator is as follows.

A stamp discriminator is prepared for each of the n feature amount calculation results C1 to Cn, and a voting result value (referred to as an F value in this embodiment) of a weighted majority decision result is obtained.

(Where αi is the weight given to each weak classifier)

The stamp weak classifier is as follows.


(Where bi is the threshold value for each feature, and sgn i is the discrimination polarity)
When the F value thus obtained is smaller than 0, it may be determined as a failure state.

<Experiment conducted by the inventor>
The inventor of the present application prepared a printer tester having the same configuration as that of the color image forming apparatus shown in FIG. 1, and performed continuous printing using this printer tester to continuously output test images. FIG. 6 shows time-series data of each feature amount until a recording medium conveyance failure occurs in the fixing device provided in the printer test machine.

6A shows the effective value of the contact / separation motor drive current, FIG. 6B shows the number of occurrences of paper jams, and FIG. 6C shows the FR deviation of the tip position of the separation plate 50.
In proportion to the sheet passing amount, the deterioration of the fixing roller 12 having the elastic layer progresses, and the contact / separation motor current value tends to decrease. It can be seen that when the paper is passed about 1000 kp, the contact / separation motor current value is greatly reduced due to the deterioration of the fixing roller 12 having the elastic layer. Also, as shown in FIG. 6B, paper jams may occur sporadically, but the frequency of occurrence increases after 1000 kp when the fixing roller 12 has deteriorated and the current value in FIG. 6A has greatly decreased. I understand that. Further, the FR deviation of the tip position of the separation plate 50 in FIG. 6c also shows a tendency that the deviation becomes large after 1000 kp.

  Then, based on the number of occurrences of paper jam, the fixing device contact / separation motor current, and the absolute position FR deviation of the leading edge of the separation plate, the threshold value, the discrimination polarity and the weighting value are determined by the boosting method, and the change in F value with time is examined saw. The result is shown in FIG. As shown in the figure, the F value shows a negative value at the time when the failure due to roller deterioration occurs, and it can be seen that the failure is accurately captured.

<Monitoring result notification means>
Information on the failure thus obtained is sent to the alarm reporting device. When notified of a failure, the alarm reporting device notifies the service engineer or user by sending an e-mail or the like. By issuing the alarm report, a service engineer or user can notice a failure and can repair the failed unit.

  That is, means for storing the number of occurrences of paper jam occurring in the fixing device 5, means for storing the current value of the contact / separation motor of the fixing device 5, and the pressure separation plate 51 on the pressure roller 14 side of the fixing device 5. If the failure including the estimation of the cause of the failure in the fixing device 5 is diagnosed by using three means, that is, the means for storing the position of the leading edge, in order to grasp the fluctuation that becomes an obstacle to the sheet conveyance performance, By detecting the contact / separation motor torque fluctuations that correlate with the change in the state of the fixing nip by the contact / separation motor current value, and by grasping the position of the pressure separation plate 51 that correlates with the separation performance of the paper on which the toner layer is placed, The cause can be easily identified and maintenance can be performed easily. This can also reduce downtime.

  When a DC motor is used as the contact / separation motor of the fixing device 5, the motor current value can be easily obtained, and can be used as a feature value for failure diagnosis. Further, if the distance measuring sensor 150 is used as a means for measuring the absolute position of the front end of the pressure separation plate 51 provided in the fixing device 5, the fluctuation amount of the front end position of the pressure separation plate 51 can be acquired. It can be used as a feature value.

  Further, as a paper conveying means of the fixing device 5, either or both of the front and back sides of the paper, a rotating body coated with silicone rubber or its foam material, or a release layer is coated on the silicone rubber or its foam material. If a rotating body is used and the diagnosis object is a failure of the rotating body, the rotating body is replaced on the basis of the failure diagnosis result without replacing the fixing device 5 itself. You can continue.

  In addition, by changing the distance from the leading edge of the paper to the unfixed toner on the paper (the amount of leading edge margin) before the failure is determined, a possible failure avoidance operation can be performed before the failure. This makes it possible to postpone the replacement of the object and use the image forming apparatus for a longer time. Also, by configuring a stamp weak discriminator that diagnoses a failure using boosting, it is possible to perform CPU computations at extremely high speed, thereby enabling highly accurate diagnosis.

  In addition, since the image forming apparatus has a large number of parts, efficient maintenance work can be performed by performing the above-described failure diagnosis.

1: Scanner unit 2: Writing unit 3: Developing unit 5: Fixing device 6: Gloss applying device 7: Carrying roller pair 8: Paper discharge unit 10: ADF (automatic document feeder)
11: Fixing belt 12: Fixing roller 13: Separating roller 15: Heating roller 15h: Heater 16: Tension roller 30: Intermediate transfer member 31: Photoreceptor 34: Secondary transfer unit 35: Conveying belt 36: Cleaning unit 37: Conveying path 38: registration units 41a, 41b, 41c, 41d: paper feed tray 50: separation plate 51: pressure separation plate 76: lever member 78: cam 80, 90: roller 85: heater 100: color copier 100A: image reading unit 100B: Image forming unit 100C: Paper feeding unit 150: Distance sensor N1: First nip N2: Second nip

Japanese Patent Laid-Open No. 06-208265 JP 2005-309077 A JP 2008-102474 A

Mathematical Sciences, No. 489, MARCH, 2004 “Information Geometry for Statistical Pattern Identification”

Claims (9)

A method for diagnosing the cause of a failure in the fixing device in an image forming apparatus including a fixing device that applies heat and pressure to a sheet onto which unfixed toner having been formed with an image is transferred by a heating roller and a pressure roller Because
Storing the number of paper jams occurring in the fixing device;
Storing the current value of the contact / separation motor of the fixing device;
Storing the position of the tip of the pressure separating plate on the pressure roller side of the fixing device;
A failure diagnosing method, wherein weighting is performed by a boosting method using the three stored data, and diagnosing a failure of an apparatus constituting the image forming apparatus including an estimation of a cause of a failure in the fixing device. . An apparatus for diagnosing the cause of a failure in the fixing device in an image forming apparatus having a fixing device that applies heat and pressure to a sheet onto which unfixed toner having been formed with an image is transferred by a heating roller and a pressure roller Because
Means for storing the number of occurrences of paper jams occurring in the fixing device;
Means for storing a current value of a contact / separation motor of the fixing device;
Means for storing the position of the pressure separation plate tip on the pressure roller side of the fixing device;
Means for weighting the data stored by the three means;
Means for determining whether each data is normal or abnormal based on the result of weighting in the means for weighting;
A failure diagnosis apparatus comprising: diagnosing a failure of an apparatus constituting the image forming apparatus including estimation of a cause of a failure in the fixing device. A fixing device that applies heat and pressure to a sheet onto which image-formed unfixed toner has been transferred with a heating roller and a pressure roller;
Means for separating and conveying the paper by a non-contact separating plate arranged on the nip exit side of the heating roller and the pressure roller, and divided into a plurality of parts;
A heating member used for smoothing the toner surface layer of the paper by holding gloss on the downstream side in the paper conveyance direction of the nip of the fixing device is held, and the temperature heated by the heating member is controlled. A gloss applying device in which a rotating body and another rotating body capable of being pressed and separated from the one rotating body are disposed, and the glossiness of the toner fixing surface of the paper is increased.
An image forming apparatus comprising: a failure diagnosis device that diagnoses a cause of failure in the fixing device,
Means for storing the number of occurrences of paper jams occurring in the fixing device;
Means for storing a current value of a contact / separation motor of the fixing device;
Means for storing the position of the tip of the pressure separation plate on the pressure roller side of the fixing device;
A failure diagnosis apparatus comprising means for diagnosing a failure including an estimation of a cause of a failure in the fixing device using the three means. In the failure diagnosis apparatus according to claim 2 or 3,
A failure diagnosis apparatus, wherein the contact / separation motor of the fixing device is a DC motor. The failure diagnosis apparatus according to any one of claims 2 to 4,
A distance measuring sensor is disposed downstream of the fixing device in the paper conveyance direction, and includes a distance measuring sensor as a means for measuring the absolute position of the front end of the pressure separating plate for separating the paper from the pressure roller,
A failure diagnosis apparatus using data measured by the distance measuring sensor for the failure diagnosis. In the failure diagnosis apparatus according to any one of claims 2 to 5,
As a sheet conveying means of the fixing device, a rotating body coated with silicone rubber or a foamed material thereof, or a rotating body coated with a release layer on the silicone rubber or the foamed material, on either or both sides of the sheet Use
A failure diagnosis apparatus characterized in that a failure diagnosis target is a failure of the rotating body. The failure diagnosis apparatus according to any one of claims 2 to 6,
A failure diagnosis apparatus characterized by increasing and changing a leading edge margin amount, which is a distance from a leading edge of a sheet to unfixed toner on the sheet, before the failure is determined. The failure diagnosis apparatus according to any one of claims 2 to 7,
A failure diagnosis apparatus comprising a stamp weak discriminator for diagnosing a failure using a boosting method. An image forming apparatus comprising the failure diagnosis apparatus according to claim 2.