JP6428366B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

  Japanese Patent Application Laid-Open No. H10-260260 discloses that an image carrier is detected by detecting a current flowing through a transfer roller.

  Patent Document 2 discloses that it is determined whether or not the output to the contact charging member is normal, and if it is determined to be abnormal, it is determined whether or not it is continuous.

  Patent Document 3 discloses that a current value of a bias voltage applied to a contact charging member is detected, and information on deterioration of the contact charging member is obtained from the detected current value.

Japanese Patent Laid-Open No. 04-101182 Japanese Patent Laid-Open No. 06-012921 Japanese Patent Laid-Open No. 11-149204

  In the case of an image forming apparatus of a type that transfers a toner image onto a sheet on a conveyance belt, there are many factors that affect fluctuations in electrical characteristics, such as tension change over time of the conveyance belt, and simple electrical characteristics such as resistance values. It is difficult to diagnose abnormalities from changes.

  An object of the present invention is to provide a technique for performing an effective abnormality diagnosis as compared with a case where update information of a maximum value or a minimum value is not considered among changes in electrical characteristics in a transfer portion.

Claim 1
An image holding body that holds the toner image by receiving the formation of the toner image while rotating;
A strip that circulates in contact with the image carrier;
A toner image that is disposed on the inner side of the belt-like body and sandwiched between the image carrier and the voltage carrier and that is held by the image carrier is transferred to the image carrier. A transfer body to be transferred onto a sheet conveyed to a transfer region sandwiched between the strips;
A first measurement unit that repeatedly measures electrical characteristics between the image carrier and the transfer body sandwiching the belt-like body at predetermined intervals;
The current measurement value obtained by the measurement in the first measurement unit is compared with the maximum value and the minimum value in the past measurement value, and the current measurement value is determined to be the maximum value of the past measurement value. An update unit that updates the maximum value and the minimum value with the current measured value when the value is above and below the minimum value, respectively.
A determination unit for determining whether or not to report a warning by a determination procedure for determining that the maximum value or the minimum value has been updated by the update unit;
An image forming apparatus comprising: a warning unit that reports a warning according to a determination result by the determination unit that a warning is reported.

Claim 2
A second measurement unit that repeatedly measures an environment including at least humidity;
According to the determination procedure, the determination unit sets the maximum value or the minimum value updated by the update unit as one of the determination materials, and further sets the environmental measurement result by the second measurement unit as one of the determination materials. The image forming apparatus according to claim 1, wherein it is determined whether or not a warning is reported.

Claim 3
The update unit records the date and time of update,
The image forming apparatus according to claim 1, wherein the determination unit further determines whether or not to report a warning according to a determination procedure in which a date and time of update is added to one of the determination materials. .

  According to a fourth aspect of the present invention, the determination unit further determines whether or not to report a warning according to a determination procedure in which the number of past image formations is added to one of the determination materials. The image forming apparatus according to any one of 3.

  According to a fifth aspect of the present invention, the first measurement unit repeats the measurement a plurality of times while the belt-like body makes a round for one opportunity, and the update unit is a plurality obtained by the plurality of measurements at the current opportunity. 6. The image forming apparatus according to claim 1, wherein an average value of the measured values is used as a measured value at the current opportunity.

Claim 6
The update unit further calculates a difference value between the maximum value and the minimum value of the plurality of measurement values obtained at the current opportunity, and the difference between the maximum value and the minimum value of the plurality of measurement values obtained at the past opportunity. When the difference value exceeds the maximum difference value, which is the maximum value among the difference values, the difference value maximum value is updated with the difference value at this time,
The determination unit further determines whether or not to report a warning according to a determination procedure in which one of the determination materials is that the maximum difference value has been updated by the update unit. 6. The image forming apparatus according to any one of items 1 to 5.

Claim 7
The determination unit determines which level among a plurality of levels for reporting an alarm,
The image according to any one of claims 1 to 6, wherein the warning unit reports a warning according to the currently determined level for reporting an alarm by the determination unit. Forming device.

  According to the image forming apparatus of the first aspect, it is possible to perform an effective abnormality diagnosis as compared with the case where the update information of the maximum value or the minimum value is not taken into account among changes in the electrical characteristics in the transfer unit.

  According to the image forming apparatus of the second aspect, it is possible to perform a more effective abnormality diagnosis than in the case where the environment such as humidity is not taken into consideration.

  According to the image forming apparatus of the third aspect, it is possible to perform more effective abnormality diagnosis than when the update date and time are not taken into consideration.

  According to the image forming apparatus of the fourth aspect, it is possible to perform more effective abnormality diagnosis than in the case where the number of past image formations is not taken into consideration.

  According to the image forming apparatus of the fifth aspect, it is possible to perform a more effective abnormality diagnosis than in the case where the measurement is performed only once during one round.

  According to the image forming apparatus of the sixth aspect, it is possible to diagnose whether or not there is a partial abnormality of the belt-like body.

  According to the image forming apparatus of the seventh aspect, it is possible to take measures according to the situation.

1 is a schematic configuration diagram of an image forming apparatus as an embodiment of the present invention. FIG. 2 is a configuration diagram illustrating a configuration of an image forming engine schematically illustrated in FIG. 1 and its surroundings. FIG. 5 is a diagram illustrating a monitoring location of a transfer bias voltage V on a paper transport belt. It is explanatory drawing of a temperature / humidity environment. It is a figure which shows the memory content, such as a measurement result. FIG. 5 is a diagram illustrating a part of an abnormality determination algorithm for a paper transport belt. FIG. 5 is a diagram illustrating a part of an abnormality determination algorithm for a paper transport belt. FIG. 5 is a diagram illustrating a part of an abnormality determination algorithm for a paper transport belt. FIG. 5 is a diagram illustrating a part of an abnormality determination algorithm for a paper transport belt. FIG. 5 is a diagram illustrating a part of an abnormality determination algorithm for a paper transport belt.

  Embodiments of the present invention will be described below.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus as an embodiment of the present invention.

  Under the image forming apparatus 100, two upper and lower paper trays 110 are provided. In each of these paper trays 110, papers before image formation are stored in a stacked state.

  An image forming engine 120 is provided on the upper part of the image forming apparatus 100. The detailed description of the image forming engine 120 will be given in FIG. 2, and in FIG. 1, the image forming engine 120 is shown by only one circle. In the image forming engine 120, a toner image is formed.

  A sheet conveying belt 130 is provided below the image forming engine 120. The paper transport belt 130 is an endless belt that is stretched by two rollers 131 and circulates and moves in the direction of the arrow B, and transports the paper on it. The sheet conveying belt 130 corresponds to an example of a belt-like body according to the present invention.

  When forming an image, one sheet is taken out from a designated paper tray 110 of the two-stage paper trays 110 by a paper take-out roll 141, and is conveyed in the direction of arrow A on the paper conveyance path 140. The sheet is fed into a transfer area sandwiched between the image forming engine 120 and the sheet conveying belt 130 by the conveying roll 142. Then, when the paper passes through the transfer area, the toner image formed by the image forming engine 120 is transferred onto the paper. The sheet on which the toner image has been transferred is further conveyed by the sheet conveying belt 130, and is heated and pressurized by the fixing device 150 to fix the toner image, thereby forming an image composed of the fixed toner image on the sheet. The paper on which the toner image is fixed by the fixing device 150 is discharged onto the paper discharge tray 161 by the paper discharge roll 143.

  In addition, the image forming apparatus 100 is provided with a manual feed tray 162. When the paper is placed on the manual feed tray 162, the paper on the manual feed tray 162 is taken in by the paper take-in roll 144 instead of being taken out from the paper tray 110, and further fed into the transfer area by the paper feed roll 142. It is. The subsequent sequence is the same as when a sheet is removed from the sheet tray 110.

  The image forming apparatus 100 also has a mode for forming images on both sides of the paper. In forming an image on both sides of the paper, first, in the same manner as described above, the paper having undergone the transfer of the toner image on the first surface and having been fixed by the fixing device 150 is moved in the direction of arrow B by the paper transport path switching member 145. And is further fed in the direction of arrow C by the paper transport rolls 146 and 147.

  Thereafter, the paper transport roll 147 reverses and the paper transport path switching member 148 acts to transport the paper in the direction of arrow D, and is further fed back to the transfer area by the paper transport roll 142. In the image forming engine 120, a toner image to be transferred to the second surface of the paper is formed in synchronization with this, and when the paper passes through the transfer area again, the toner image is transferred to the second surface of the paper. The sheet on which the toner image has been transferred to the second surface is conveyed by the sheet conveying belt 130, and the toner image on the second surface is fixed by the fixing device 150. This time, the sheet conveying path switching member 145 causes the sheet discharge roll 143 side to be fixed. And is discharged onto a paper discharge tray 161 by a paper carry-out roll 143. The paper discharged at this time is formed with images composed of fixed toner images on both sides thereof.

  Further, the image forming apparatus 100 includes a UI (user interface) 170 and a control unit 180. The UI 170 includes a display unit (not shown) and an operation unit, and the display unit displays the state of the image forming apparatus 100, an operation menu, and the like. In the operation unit, various instructions by the user of the image forming apparatus 100 are input.

  The control unit 180 is responsible for overall control of the image forming apparatus 100, and causes the image forming apparatus 100 to perform an operation corresponding to a user operation on the UI 170.

  FIG. 2 is a block diagram showing the configuration of the image forming engine schematically shown in FIG. 1 and its surroundings.

  The image forming engine 120 includes a photoreceptor 121 that rotates in the direction of the arrow R1. The photosensitive member 121 is an example of an image holding member according to the present invention.

  Further, the image forming engine 120 includes a charger 122, an exposure device 123, a developing device 124, a density sensor 125, a transfer roll 126, and a cleaner 127 around the photosensitive member 121.

  The charger 122 uniformly charges the surface of the photoconductor 121.

  The exposure device 123 irradiates the photosensitive member 121 with the exposure light 123a modulated in accordance with the image signal, thereby forming an electrostatic latent image on the photosensitive member 121.

  The developing device 124 develops the electrostatic latent image formed on the photoconductor 121 with toner, and forms a toner image on the photoconductor 121. Here, the developer 124 contains a developer containing toner, and the developer is circulated while being stirred in a direction perpendicular to the paper surface of FIG. 2 by the two developer conveying members 124a. Being transported. The developing device 124 is provided with a developing roll 124b. A developing bias voltage is applied to the developing roll 124b. The developing roll 124b rotates in the direction of the arrow R2 while holding the developer on the surface thereof, and carries the developer to the developing area facing the photoreceptor 121, and the electrostatic latent image on the photoreceptor 121 is transferred to the developer. Develop with the toner inside.

  The developer that has not been used for development is further conveyed by the developing roll 124b and returned to the developing device 124. The developing device 124 is further provided with a film-like seal member 124c. The seal member 124c is in contact with the photosensitive member 121 and prevents the toner from leaking upward from the gap between the developing device 124 and the photosensitive member 121. The toner leaking to the lower side of the developing device 124 is sucked by the suction device 190 so as not to diffuse into the image forming apparatus 100.

  The suction device 190 includes a fan 191 and a filter 192, and a suction port 193 for sucking toner is provided at a position adjacent to the downstream side of the developing device 124 with respect to the rotation direction (arrow R2 direction) of the developing device 121. Yes. When the fan 191 rotates, air containing toner leaking from the developing device 124 is sucked from the suction port 193 in the direction of the arrow X. The filter 192 adsorbs the toner in the sucked air. The remaining air sucked from the suction port 193 and from which the toner has been removed by the filter 192 is exhausted to the outside of the image forming apparatus 100 in the direction of arrow Y.

  The transfer roll 126 is disposed inside the paper transport belt 130 and at a position facing the photoconductor 121 with the paper transport belt 130 interposed therebetween. A bias power supply 161 is connected to the transfer roll 126, and a transfer bias voltage V is applied by the bias power supply 161. Here, since the photoconductor 121 is grounded, the transfer bias voltage V is applied between the photoconductor 121 and the transfer roll 126. Further, the two rolls 131 that support the paper transport belt 130 are also grounded. The transfer roll 126 receives the transfer bias voltage V and transfers the toner image on the photoconductor 121 onto the paper that has been fed into the transfer region W. The transfer roll 126 corresponds to an example of a transfer body according to the present invention.

  As described above, the sheet on which the toner image has been transferred is further conveyed by the sheet conveying belt 130 and passes through the fixing device 150. The toner image on the paper is fixed by passing through the fixing device 150, and an image composed of the fixed toner image is formed on the paper.

  Here, the bias power supply 161 is a constant current power supply, and applies a transfer bias voltage V so that a constant current I instructed by the control unit 180 (see FIG. 1) flows. Therefore, when the resistance value changes, the applied transfer bias voltage V changes so that the current I becomes constant. Therefore, here, the transfer bias voltage V is monitored. Based on the transfer bias voltage V, an electrical characteristic (resistance value in this case) between the photosensitive member 121 and the transfer roll 126 is recognized. This monitoring of the transfer bias voltage corresponds to an example of the first measurement unit referred to in the present invention.

  In the present embodiment, the transfer is performed at each time triggered by a predetermined opportunity, for example, when a predetermined number of images (for example, 100 sheets) are printed out using the image forming apparatus 100. The transfer bias voltage V applied to the roll 126 is monitored. This monitor determines whether there is an abnormality in the image forming apparatus 100 through an abnormality determination process described later.

  Here, as an abnormality that appears as a change in the transfer bias voltage V, for example, a wiring failure such as a disconnection or a short circuit between the bias power supply 161 and the transfer roll 126, or a contact between the photosensitive member 121 and the paper transport belt 130. There may be a defect, excessive pressure, abnormal contamination of the photosensitive member 121 or the paper transport belt 130, and the like.

  FIG. 3 is a diagram showing the monitoring location of the transfer bias voltage V on the paper transport belt.

  FIG. 3A is a development view of the paper transport belt. The endless sheet conveying belt 130 (see FIGS. 1 and 2) is an endless belt, but here, one of the ends is cut and straightened.

  Here, the transfer bias voltage V is measured at 20 locations at equal intervals while the paper transport belt 130 makes one round with one trigger of measurement.

  FIG. 3B is a diagram showing measured values and average values of the transfer bias voltages V at 20 locations on the paper transport belt.

  Since the measured values vary somewhat at each measurement location of the paper conveyance belt 130, the average value of the measurement values at 20 locations is calculated here, and the average value is used as the measurement value of the transfer bias voltage V at this time. The In addition, here, a difference value between the maximum value and the minimum value among the 20 measured values at this time is calculated.

  In addition, the temperature and humidity of the environment are measured by the environment sensor 190 (see FIG. 1) for each trigger of measurement.

  FIG. 4 is an explanatory diagram of a temperature and humidity environment.

  In FIG. 4, the horizontal axis represents relative humidity (% RH), and the vertical axis represents humidity (° C.).

  Here, as an example, an environment of 70% RH or higher and 28 ° C. or higher is a “high temperature and high humidity” environment (represented by “HH”), an environment of 30% RH or lower and 10 ° C. or lower is a “low temperature and low humidity” environment ( Designated as “LL”).

  When in the HH environment, the resistance value of the paper transport belt 130 tends to decrease. Therefore, the transfer bias voltage V decreases. When in the LL environment, the resistance value of the paper transport belt 130 tends to increase. Therefore, the transfer bias voltage V increases.

  Here, both the temperature and the humidity are measured by the environmental sensor 900. However, since the humidity greatly contributes to the change in the resistance value of the paper conveying belt 130, both the temperature and the humidity are measured. Instead, only the humidity may be measured.

  FIG. 5 is a diagram showing stored contents such as measurement results.

  The contents shown in FIG. 5A are stored in the control unit 180 shown in FIG. 1 and are sequentially updated. FIG. 5B is an example of stored values of the contents shown in FIG.

  6 to 10 are diagrams showing an abnormality determination algorithm for the paper transport belt, which is accompanied by a printing operation in the image forming apparatus shown in FIG.

  When the printing operation in the image forming apparatus 100 is executed, first, the print number counter is incremented by 1 (step S101). Next, it is determined whether or not an opportunity for measurement has arrived (step S102). In this embodiment, the measurement is repeated every time 100 sheets are printed. Therefore, in this step S102, it is determined whether or not the measurement trigger has arrived depending on whether or not the number of printed sheets has reached a multiple of 100.

  Next, as described with reference to FIG. 3, the transfer bias voltage V is measured at 20 locations during one rotation of the sheet conveying belt 130 (step S <b> 103), and an average value of the measured values at the 20 locations is calculated. Further, a difference value between the maximum value and the minimum value among the 20 measured values is calculated (step S105). Furthermore, environmental temperature and humidity are measured by the environmental sensor 900 (see FIG. 1) (step S106).

  Next, the list update process shown in FIG. 5 is performed.

  Here, first, “cumulative print number” in the list shown in FIG. 5 is updated (step S107), and “environment” is updated (step S108). In the example of FIG. 5, “cumulative print number” = 10,000 and “environment” = HH (high temperature and high humidity) are recorded.

  Further, it is determined whether or not the “average value” calculated this time exceeds the stored “maximum value” (step S109), and when the “average value” exceeds the “maximum value”, “ The “maximum value” is updated with the “average value” (step S110). In the example shown in FIG. 5, 1050 is recorded as the “maximum value”. On the other hand, if the “average value” does not exceed the “maximum value”, the “maximum value” is not updated, and the “maximum value continuous update count” is decremented by 1 (step S111). However, “maximum value continuous update count” = 0 is set as the lower limit.

  As will be described later, in the abnormality determination algorithms shown in FIGS. 6 to 10, there is a problem of how many times the three “continuous update counts” including the “maximum value continuous update count” are continuously updated. However, when the continuous update is interrupted even once, it is not cleared to zero and the number of continuous updates is not counted from the beginning. In this embodiment, when the update is interrupted, the “continuous update count” is subtracted. Therefore, it is devised to reflect the case where it is not always strictly continuous.

  In step S109, it is determined whether or not the average value of the measured values at the current 20 locations exceeds the “maximum value” stored in the list of FIG. When the “average value” exceeds the “maximum value”, the “maximum value” is updated with the “average value” (step S110). That is, the current “average value” is overwritten in the column in FIG. 5 where “maximum value” is stored. On the other hand, when the “average value” does not exceed the “maximum value”, the “maximum value” is not updated, and the “maximum value continuous update count” is decremented by 1 (step S111). However, “maximum value continuous update count” = 0 is set as the lower limit.

  Further, in step S112, it is determined whether or not the average value of the measured values at the current 20 locations is below the “minimum value” stored in the list of FIG. When the “average value” is lower than the “minimum value”, the “minimum value” is updated with the “average value”. (Step S113). On the other hand, if the “average value” is not less than the “minimum value”, the “minimum value” is not updated, and the “minimum value continuous update count” is decremented by 1 (step S114). However, “minimum value continuous update count” = 0 is set as the lower limit.

  Further, it is determined whether or not the “difference value” obtained by subtracting the “minimum value” from the “maximum value” among the 20 measured values at this time exceeds the “difference value maximum value” shown in FIG. (Step S115). When the “difference value” exceeds the “difference value maximum value”, the “difference value maximum value” is updated with the “difference value” (step S116). If the “difference value” does not exceed the “difference value maximum value”, the “difference value maximum value” is not updated, and the “difference value maximum value continuous update count” is decremented by 1 (step S117). . However, “maximum difference value continuous update count” = 0 is set as the lower limit.

  Next, the process proceeds to a process for determining whether or not an abnormality has occurred.

  First, in step S201 in FIG. 7, it is determined whether or not the “cumulative print number” is 3,000. If the “cumulative print number” is 3,000, the “maximum value continuous update count” shown in FIG. "," Minimum value continuous update count ", and" difference value maximum continuous update count "are once cleared to zero (step S202). The “cumulative number of prints” can be set to a preferable number as appropriate.

  Until the cumulative number of prints reaches 3,000, the "maximum value continuous update count", "minimum value continuous update count", and "difference value maximum continuous update count" can be continuously updated even if there is no abnormality. The treatment is so high that it is not judged as abnormal.

  Next, it is determined whether or not the “total number of prints” exceeds 3,000 (step S203). If the “total number of prints” does not exceed 3,000, the process ends without proceeding to the abnormality determination process. Next, when the printing operation is performed, this processing is executed again from “Start” in FIG.

  When the “total number of prints” exceeds 3,000, an abnormality determination process described below is performed.

  Here, an abnormality determination process based on the “maximum value continuous update count”, an abnormality determination process based on the “minimum value continuous update count”, and an abnormality determination process based on the “difference value maximum continuous update count” are arranged in this order. Done.

  First, it is determined whether or not “maximum value continuous update count” = 0 (step S204). When “maximum value continuous update count” = 0, no abnormality is found based on “maximum value continuous update count”, and the routine proceeds to an abnormality determination process based on “minimum value continuous update count” (see FIG. 9).

  When “maximum value continuous update count” = 0 is not 0, it is determined whether “cumulative print count” = 30,000 or more (step S205).

  As the cumulative number of printed sheets increases, the adhesion of the discharge product to the back surface of the paper transport belt 130 (the surface on the side where the transfer roll 126 is in contact) increases. This discharge product tends to decrease the resistance value of the paper conveying belt 130 by reacting with moisture in the air. Therefore, in the present embodiment, the criterion for abnormality determination is changed depending on whether the “cumulative print number” is less than 30,000 or more than 30,000.

  Here, the processing when the “cumulative print number” is less than 30,000 will be described first.

  At this time, it is determined whether the “maximum value continuous update count” is 1 or 2, or 3 or more (step S206). When the “maximum value continuous update count” is 1 or 2, it is determined whether or not the environment is “high temperature and high humidity” (HH) (step S207).

  Under the environment of “high temperature and high humidity” (HH), the resistance value of the sheet conveying belt 130 decreases, and therefore the transfer bias voltage V tends to decrease. Nevertheless, the fact that the “maximum value” is updated may mean that some abnormality is acting.

  Therefore, when it is determined in step S207 that the environment is “high temperature and high humidity”, a warning is reported (step S208).

  In the following, as will be described sequentially, three levels of warnings are prepared according to the possibility of abnormality. When the “maximum value continuous update count” is 1 or 2, there is a possibility of an abnormality but it is still at a low level, so here, a first-stage warning (alarm 1) is reported. Specifically, for example, a message “Check the printed image” is displayed on the display screen of the UI 170 (see FIG. 1). On the other hand, if it is determined in step S207 that the environment is not in a “high temperature and high humidity” environment, a warning is not reported at this stage, and the process proceeds to an abnormality determination process (see FIG. 9) based on “the minimum number of continuous updates” To do.

  If it is determined in step S206 that the “maximum value continuous update count” is 3 or more, then it is determined whether the “maximum value continuous update count” is in the range of 3 to 5 or 6 or more. (Step S209). When the “maximum value continuous update count” is in the range of 3 to 5, it is determined whether or not the environment is “high temperature and high humidity” (step S210). If it is determined that the environment is in a “high temperature and high humidity” environment, a second-stage warning (alarm 2) is reported here (step S211). In this second stage, the message “There is a possibility that an abnormality has occurred. If there is an abnormality in the printed image, please stop the device and contact us.” Is displayed on the UI 170 display screen. Is done.

  If it is determined in step S210 that the environment is not in a “high temperature and high humidity” environment, a first-stage warning (see the description of step S208) is reported (step S212).

  If it is determined in step S209 that the “maximum value continuous update count” is 6 or more, it is then determined whether or not the “maximum value continuous update count” is in the range of 6 to 10. (Step S213). When the “maximum value continuous update count” is in the range of 6 to 10, it is determined whether or not the environment is “high temperature and high humidity” (step S214). When it is not under the environment of “high temperature and high humidity”, the warning (alarm 2) at the second stage remains (step S215).

  When the environment is "high temperature and high humidity", a third-stage warning (alarm 3) is issued (step S216). In step S213, if the “maximum value continuous update count” exceeds 10, a third-stage warning (alarm 3) is performed regardless of whether the environment is “high temperature and high humidity”. (Step S216).

  As the warning in the third stage, for example, a message “An error has occurred. The device will be stopped” is displayed on the display screen of the UI 170. In this case, the operation of the apparatus is further stopped (step S217), and the abnormality determination process is terminated.

  Next, an abnormality determination process based on the “maximum value continuous update count” when it is determined in step S205 that the “cumulative print number” exceeds 30,000 will be described with reference to FIG. . Here, only the differences will be described in contrast to the processing when the “cumulative print number” shown in FIG. 7 is less than 30,000.

  In the processing in which the “cumulative print number” shown in FIG. 7 is less than 30,000, in steps S206, S209, and S213, whether or not the “maximum value continuous update count” is 1 or 2, respectively, It is determined whether it is within the range or whether it is within the range of 6 to 10. On the other hand, in the processing in which the “cumulative print number” is 30,000 or more shown in FIG. 8, “maximum value continuous update” is performed in steps S306, S309, and S313 corresponding to steps S206, S209, and S213 in FIG. It is determined whether the “number of times” is 1, whether it is in the range of 2 to 4, or whether it is in the range of 5 to 8. That is, the warning level is increased when the “maximum value continuous update count” is smaller than when the “cumulative print count” is less than 30,000.

  As described above, when the “cumulative print number” increases, the discharge product adheres more to the back surface of the paper conveyance belt 130 and reacts with moisture in the air to reduce the resistance value of the paper conveyance belt 130, and thus the transfer bias. The voltage V tends to decrease. Nevertheless, the fact that the “maximum value” is updated means that the possibility of abnormality is high. Therefore, in this embodiment, the determination criterion is changed depending on whether the “cumulative print number” is less than 30,000 or more.

  The other steps (steps S307, S308, S310 to S312, and S314 to S317) in the processing when the “cumulative print number” shown in FIG. 8 is 30,000 or more are “cumulative print number” shown in FIG. This is the same as the corresponding step (steps S207, S208, S210 to S212, S214 to S217) when the number is less than 30,000, and a description thereof will be omitted.

  The above is the abnormality determination processing based on the “maximum value continuous update count”.

  Next, the abnormality determination process based on the “minimum value continuous update count” will be described. The abnormality determination process based on the “minimum value continuous update count” is compared with the above-described abnormality determination process based on the “maximum value continuous update count”. The difference is that the determination is made as to whether or not it is in a “low temperature and low humidity” environment.

  In addition, in the abnormality determination process based on the “maximum value continuous update count”, the determination criterion is divided according to whether the “cumulative print number” is less than 30,000 sheets or more than 30,000 sheets. This is because the decrease in the resistance value of the sheet conveying belt 130 in the “high temperature and high humidity” environment due to the “number of sheets” is focused. On the other hand, here, the question is whether or not it is in a “low temperature and low humidity” environment rather than a “high temperature and high humidity” environment. Therefore, here, the “cumulative print number” will be described using a form that is not considered. Note that the “cumulative number of prints” not considered this time may affect the change in the resistance value depending on the material selection of the transfer roll 126, and in that case, it is appropriately adopted as a criterion. Needless to say, you can.

  Here, it is first determined whether or not “minimum value continuous update count” = 0 (FIG. 9, step S404).

  When “minimum value continuous update count” = 0, no abnormality is found based on “minimum value continuous update count”, and the process proceeds to abnormality determination processing based on “difference value maximum continuous update count” (see FIG. 10). To do.

  When “minimum value continuous update count” is not 0, it is first determined whether “minimum value continuous update count” is 1 or 2, or 3 or more (step S406). When the “minimum value continuous update count” is 1 or 2, it is determined whether or not the environment is “low temperature and low humidity” (step S407).

  Under the environment of “low temperature and low humidity”, the resistance value of the sheet conveying belt 130 increases, and therefore the transfer bias voltage V tends to increase. Nevertheless, the fact that the “minimum value” is updated may mean that some abnormality is acting. Therefore, if it is determined in step S407 that the environment is "low temperature and low humidity", a warning is reported (step S408).

  However, here, since the “minimum value continuous update count” is 1 or 2, there is a possibility of an abnormality, but it is still considered to be a low level, and a first-stage warning (alarm 1) is reported. Specifically, for example, a message “Please check the printed image” is displayed on the display screen of the UI 170 (see the drawing). However, if “alarm 2” has already been issued in the processing based on the “maximum value continuous update count”, step S408 is skipped and “alarm 2” is continued.

  If it is determined in step S407 that the environment is not in a “low temperature and low humidity” environment, a warning is not reported at this stage, and the process proceeds to an abnormality determination process (see FIG. 10) based on the “difference value minimum continuous update count”. .

  If it is determined in step S406 that the “minimum value continuous update count” is 3 or more, then it is determined whether the “minimum value continuous update count” is in the range of 3 to 5 or 6 or more. (Step S409). When the “minimum value continuous update count” is in the range of 3 to 5, it is determined whether or not the environment is “low temperature and low humidity” (step S410). If it is determined that the environment is “low temperature and low humidity”, a second-stage warning (alarm 2) is reported (step S411). In this second stage, the message “There is a possibility that an abnormality has occurred. If there is an abnormality in the printed image, please stop the device and contact us.” Is displayed on the UI 170 display screen. Is done.

  When it is determined in step S410 that the environment is not in the “low temperature and low humidity” environment, the warning is only in the first stage (see the explanation of step S408) (step S412). However, if the warning has already shifted to the second stage, the alarm 1 process in step S412 is not performed.

  If it is determined in step S409 that the “minimum value continuous update count” is 6 or more, it is then determined whether or not the “minimum value continuous update count” is in the range of 6 to 10. (Step S413). When the “maximum value continuous update count” is in the range of 6 to 10, it is determined whether or not the environment is “low temperature and low humidity” (step S414). When it is not in the “low temperature and low humidity” environment, the warning (alarm 2) of the second stage remains (step S415).

  When the environment is “low temperature and low humidity”, a third-stage warning (alarm 3) is issued (step S416). If the “minimum value continuous update count” exceeds 10 in step S413, a third-stage warning (alarm 3) is issued regardless of whether the environment is “low temperature and low humidity”. (Step S416).

  As the warning in the third stage, for example, a message “An error has occurred. The device will be stopped” is displayed on the display screen of the UI 170. In this case, the operation of the apparatus is further stopped (step S417), and the abnormality determination process is terminated.

  If it is in the “alarm 1” or “alarm 2” stage, the routine then proceeds to an abnormality determination process based on the “difference value maximum number of continuous updates” shown in FIG. However, the abnormality determination process based on the “difference value maximum continuous update count” may be omitted when the risk of partial damage of the paper transport belt is low.

  In the abnormality determination process based on this “difference value maximum value continuous update count”, it is determined whether the “difference value maximum value continuous update count” is 3 or more. When the “difference value maximum value continuous update count” is 1 or 2, the “difference value maximum value” may have been updated by noise, and thus the abnormality determination process is terminated without reporting a warning. .

  On the other hand, when the “maximum difference value maximum number of updates” is 3 or more, it is difficult to consider updating with noise, and there is a high possibility that some abnormality has occurred. Therefore, here, at this time, a third-stage warning (alarm 3) is reported (step S502), and the apparatus is stopped (step S503).

  In the above abnormality determination process, when the third stage warning is reported and the apparatus is stopped, the user of the apparatus contacts the repair person and requests repair. When staying at the first and second stage warnings, the user can continue to use the device, but the user pays attention to the quality of the printed image according to the stage of the warning and anomalies are recognized. If this happens, you will be asked to repair it.

  In the embodiment described above, the presence / absence of an abnormality is determined by paying attention to the number of continuous updates of “maximum value”, “minimum value”, and “maximum difference value”. For this reason, it is possible to correctly determine whether or not there is an abnormality with respect to an object such as a paper conveyance belt, which has various resistance value fluctuation factors and has a large resistance value fluctuation.

  Note that only the number of continuous updates is focused here, but in addition to the determination based on the number of continuous updates, for example, whether or not the difference between the “maximum value” and the “minimum value” exceeds a threshold, or a single measurement. More accurate abnormality determination processing may be realized in combination with other determination algorithms, such as whether or not the difference value between the maximum value and the minimum value of the 20 measured values being triggered exceeds a threshold value. .

  Further, here, both the temperature and humidity inside the apparatus are measured by the environmental sensor 900 (see FIG. 1). However, the humidity affects the fluctuation of the resistance value of the paper transport belt 130. Therefore, only humidity may be used for abnormality determination.

  Alternatively, instead of measuring the environment, record the date of update of the “maximum value” and “minimum value”, estimate the environment from the season and time zone that can be known from the date and time, and perform an abnormality determination process on the estimated environment. You may use for. For example, if it is expected that the paper is in a high temperature environment during the rainy season and the resistance value of the paper transport belt should have decreased, there may be an abnormality when the “maximum value” is updated. You may judge.

DESCRIPTION OF SYMBOLS 100 Image forming apparatus 120 Image forming engine 121 Photoconductor 126 Transfer roll 130 Paper conveyance belt 161 Bias power supply 170 UI
180 Control unit 190 Aspirator

Claims (7)

An image holding body that holds the toner image by receiving the formation of the toner image while rotating;
A strip that circulates in contact with the image carrier;
A toner image that is disposed on the inner side of the belt-like body and sandwiched between the image carrier and the voltage carrier and that is held by the image carrier is transferred to the image carrier. A transfer body to be transferred onto a sheet conveyed to a transfer region sandwiched between the strips;
A first measurement unit that repeatedly measures electrical characteristics between the image carrier and the transfer body sandwiching the belt-like body at predetermined intervals;
The current measurement value obtained by the measurement in the first measurement unit is compared with the maximum value and the minimum value in the past measurement value, and the current measurement value is determined to be the maximum value of the past measurement value. An update unit that updates the maximum value and the minimum value with the current measured value when the value is above and below the minimum value, respectively.
A determination unit for determining whether or not to report a warning by a determination procedure for determining that the maximum value or the minimum value has been updated by the update unit;
An image forming apparatus comprising: a warning unit that reports a warning according to a determination result by the determination unit that a warning is reported. A second measurement unit that repeatedly measures an environment including at least humidity;
According to the determination procedure, the determination unit sets the maximum value or the minimum value updated by the update unit as one of the determination materials, and further sets the environmental measurement result by the second measurement unit as one of the determination materials. The image forming apparatus according to claim 1, wherein it is determined whether or not a warning is reported. The update unit records the date and time of update,
The image forming apparatus according to claim 1, wherein the determination unit further determines whether or not to report a warning according to a determination procedure in which a date and time of update is added to one of the determination materials. .   4. The method according to claim 1, wherein the determination unit further determines whether or not to report a warning according to a determination procedure in which the number of past image formations is added to one of the determination materials. 2. The image forming apparatus according to item 1. The first measuring unit repeats the measurement a plurality of times while the belt-like body makes a round for one opportunity,
6. The update unit according to any one of claims 1 to 5, wherein an average value of a plurality of measurement values obtained by a plurality of measurements at the current opportunity is used as a measurement value at the current opportunity. The image forming apparatus according to claim 1. The update unit further includes a difference value between the maximum value and the minimum value of the plurality of measurement values obtained at the present opportunity, and the difference between the maximum value and the minimum value of the plurality of measurement values obtained at the past opportunity. When the difference value exceeds the maximum difference value, which is the maximum value among the difference values, the difference value maximum value is updated with the difference value at this time,
The determination unit further determines whether or not to report a warning according to a determination procedure in which one of the determination materials is that the maximum difference value has been updated by the update unit. 6. The image forming apparatus according to any one of items 1 to 5. The determination unit determines which level among a plurality of levels for reporting an alarm,
The image according to any one of claims 1 to 6, wherein the warning unit reports a warning according to the currently determined level for reporting an alarm by the determination unit. Forming equipment.