JP6205940B2 - Abnormality diagnosis device for replenishment mechanism, image forming apparatus, and abnormality diagnosis program for replenishment mechanism - Google Patents

Description

  The present invention relates to an abnormality diagnosis device for a supply mechanism, an image forming apparatus, and an abnormality diagnosis program for a supply mechanism.

  Patent Document 1 discloses a toner replenishing device when the toner density detected by the density detecting means becomes smaller than a predetermined limit value (L1) in a state where the cumulative rotation speed of the replenishing screw has not reached a predetermined value. A configuration for determining a failure is disclosed.

Japanese Patent No. 4827333

  An object of the present invention is to appropriately diagnose an abnormality in a replenishment mechanism in accordance with a developer replenishment and consumption situation.

  The abnormality diagnosis device for a replenishment mechanism according to claim 1 of the present invention is based on a cumulative pixel count value of an output image and a developer replenishment time by a replenishment mechanism that replenishes a developer with developer. An estimation means for estimating that there is a possibility of abnormality in the mechanism, and a diagnosis means for diagnosing whether or not there is an abnormality in the supply mechanism when the estimation means estimates that there is a possibility of abnormality in the supply mechanism; It is equipped with.

  The abnormality diagnosis device for a replenishment mechanism according to a second aspect of the present invention is the abnormality diagnosis device for the replenishment mechanism according to the first aspect, wherein the estimating means is configured to calculate the pixel count with respect to the developer replenishment time. The number of times that the accumulated value falls outside the allowable range is counted, and when the number reaches a predetermined threshold, it is estimated that the replenishment mechanism may be abnormal.

  The abnormality diagnosis device for a replenishment mechanism according to a third aspect of the present invention is the abnormality diagnosis device for the replenishment mechanism according to a second aspect, wherein the estimating means is configured to calculate the pixel count with respect to the developer replenishment time. If the accumulated value is within the allowable range, the number of times is set to the initial state.

  The abnormality diagnosis device for a replenishment mechanism according to claim 4 of the present invention is the abnormality diagnosis device for a replenishment mechanism according to any one of claims 1 to 3, wherein the diagnosis means supplies developer to be supplied to the developing unit. When the remaining amount of the developer in the storage unit to be stored is larger than a predetermined minimum remaining amount, the measurement result of the toner concentration measuring means for measuring the toner concentration in the developing unit, the pixel count cumulative value, The difference between the target value determined according to the developer replenishment time exceeds the deviation value determined according to the cumulative value of the pixel count and the developer replenishment time, and the output image per recording medium When the average pixel count value exceeds a predetermined pixel count value, the number of times of satisfaction that satisfies the condition of the number is satisfied, and when the number of satisfaction times reaches a predetermined threshold, the replenishment mechanism To diagnose that there is an abnormality.

  The abnormality diagnosis device for a toner replenishment mechanism according to a fifth aspect of the present invention is the abnormality diagnosis device for a toner replenishment mechanism according to any one of the first to third aspects, wherein the diagnosis means is a development replenished to the developing unit. The remaining amount of the developer in the storage unit for storing the developer is greater than a predetermined minimum remaining amount, and the measurement result of the toner concentration measuring means for measuring the toner concentration in the developing unit and the accumulated pixel count The number of times of satisfaction that satisfies the condition that the difference between the value and the target value determined according to the developer replenishment time exceeds the deviation value determined according to the pixel count cumulative value and the developer replenishment time. Counting and diagnosing that there is an abnormality in the replenishment mechanism when the number of fulfillment reaches a predetermined threshold.

The abnormality diagnosis device for a toner replenishment mechanism according to a sixth aspect of the present invention is the abnormality diagnosis device for the replenishment mechanism according to the fourth or fifth aspect , wherein the diagnostic means accommodates a developer to be replenished to the developing unit. In the case where the remaining amount of developer in the section is greater than a predetermined minimum remaining amount, the recording medium is classified into a plurality of categories corresponding to the average image density for each recording medium, and the toner density measuring unit is classified for each category. A category average value that is an average value of a difference between the measurement result and a target value determined in accordance with the pixel count cumulative value and the developer replenishment time, and the one of the predetermined categories among the plurality of categories. A difference of a category average value, which is a difference between the average value and the average value of the other category, and a category having a relatively high average image density among the other categories. Is equal to or less than a predetermined threshold value, the number of satisfaction satisfying that the category average value is equal to or less than a predetermined threshold value is counted for a category having a relatively low average image density among the plurality of categories. When the number of times of satisfaction reaches a predetermined threshold value, it is diagnosed that the supply mechanism is abnormal.

  The abnormality diagnosis device for a toner replenishment mechanism according to a seventh aspect of the present invention is the abnormality diagnosis device for the replenishment mechanism according to any one of the fourth to sixth aspects, wherein the diagnosis means satisfies the condition when the condition is not satisfied. Set the number of times to the initial state.

The image forming apparatus according to claim 8 of the present invention, the a current image portion, and the supply mechanism, and the abnormality diagnostic device of the replenishing mechanism according to claim 7 any one of claims performing abnormality diagnosis of該補supply mechanism An image forming unit that forms an image on a recording medium using the developer supplied from the developing unit, and a notification unit that notifies that there is at least an abnormality as a result of the abnormality diagnosis of the replenishment mechanism. Yes.

  The abnormality diagnosis program for a replenishment mechanism according to claim 9 of the present invention comprises a computer, an estimation means according to any one of claims 1 to 7, and a diagnosis means according to any one of claims 1 to 7. To function as.

  According to the abnormality diagnosis device for the replenishment mechanism according to claim 1 of the present invention, the abnormality of the replenishment mechanism is compared with that in which the abnormality diagnosis is not performed based on the correlation between the pixel count accumulated value of the output image and the developer replenishment time. Diagnosis can be appropriately made according to the supply and consumption of the developer.

  According to the abnormality diagnosis device for the replenishment mechanism of the second aspect of the present invention, the number of times that the developer replenishment time falls outside the allowable range of the pixel count cumulative value with respect to the developer replenishment time is counted, and the number of times is determined in advance. When the value of the supply mechanism is reached, it is possible to appropriately diagnose the abnormality of the replenishment mechanism in accordance with the replenishment and consumption status of the developer as compared with the case where it is not estimated that the replenishment mechanism may be abnormal.

  According to the abnormality diagnosis device for the replenishment mechanism according to claim 3 of the present invention, when the developer replenishment time is within the allowable range of the pixel count accumulated value with respect to the developer replenishment time, the number of times outside the allowable range is not set to the initial state. Compared to the case, an abnormality of the supply mechanism can be appropriately diagnosed according to the supply and consumption status of the developer.

  According to the abnormality diagnosis device for the replenishment mechanism of claim 4 of the present invention, the abnormality of the replenishment mechanism is appropriately diagnosed according to the replenishment and consumption status of the developer as compared with the case where the diagnosis means of claim 4 is not provided. can do.

  According to the abnormality diagnosis device for the replenishment mechanism of claim 5 of the present invention, the abnormality of the replenishment mechanism is appropriately diagnosed according to the replenishment and consumption status of the developer as compared with the case of not having the diagnosis means of claim 5. can do.

  According to the abnormality diagnosis device for the replenishment mechanism of claim 6 of the present invention, the abnormality of the replenishment mechanism is appropriately diagnosed according to the replenishment and consumption status of the developer as compared with the case of not having the diagnosis means of claim 6. can do.

  According to the abnormality diagnosis device for the replenishment mechanism of the seventh aspect of the present invention, the abnormality of the replenishment mechanism is detected as compared with the case where the number of times of satisfaction is not set to the initial state when the conditions of the fourth to sixth aspects are not satisfied. Diagnosis can be made appropriately according to the supply and consumption situation.

  According to the image forming apparatus of the eighth aspect of the present invention, the pixel count cumulative value of the output image and the development are compared with those in which abnormality diagnosis is not performed based on the correlation between the pixel count cumulative value of the output image and the developer replenishment time. As a result of the abnormality diagnosis of the replenishment mechanism based on the correlation with the agent replenishment time, at least an abnormality can be notified.

  According to the abnormality diagnosis program for the replenishment mechanism according to claim 9 of the present invention, the computer can function as the estimating means according to any one of claims 1 to 7 or the judging means according to any one of claims 1 to 7. .

1 is a schematic diagram illustrating an overall configuration of an image forming apparatus according to a first embodiment. 1 is a schematic diagram illustrating a configuration of a replenishment mechanism that constitutes an image forming apparatus according to a first embodiment. FIG. 3 is a control block diagram illustrating a relationship between a control unit according to the first embodiment and each unit of the image forming apparatus. And the upper limit Y _U and the lower limit Y _L of the developer supply time Y for the first pixel count cumulative value X according to the embodiment of the an example of a developer replenishing time Y of transition for the pixel count cumulative value X obtained, the It is a graph to show. It is a flowchart of the abnormal condition estimation method of the supply mechanism which concerns on 1st Embodiment. It is a flowchart of the abnormality diagnosis method of the replenishment mechanism which concerns on 1st Embodiment. It is a flowchart of the abnormality diagnosis method of the supply mechanism which concerns on the modification of 1st Embodiment. It is a flowchart of the abnormality diagnosis method of the replenishment mechanism which concerns on 2nd Embodiment. It is a table | surface which shows the relationship between the average image density used with the abnormality diagnosis method of the replenishment mechanism which concerns on 2nd Embodiment, and the density average for every category.

<< First Embodiment >>
An example of an embodiment of the present invention will be described with reference to the drawings. First, the overall configuration and operation of the image forming apparatus will be described, and then the main part of the present embodiment will be described. In the following description, the direction indicated by the arrow H in FIG. 1 is the apparatus height direction, and the apparatus width direction is the direction indicated by the arrow W in FIG. In addition, a direction perpendicular to each of the apparatus height direction and the apparatus width direction (shown by an arrow D as appropriate) is defined as an apparatus depth direction.

<Overall configuration of image forming apparatus>
"The entire"
FIG. 1 is a schematic diagram illustrating an overall configuration of an image forming apparatus 10 according to the present embodiment as viewed from the front side. As shown in this figure, the image forming apparatus 10 includes an image forming unit 8 and a control unit 24. Here, the control unit 24 is an example of an abnormality diagnosis device and a computer for the supply mechanism 22 described later.

  The image forming unit 8 includes a medium storage unit 12, a toner image forming unit 14, a transport unit 16, a fixing device 18, a discharge unit 20, and a supply mechanism 22. The image forming unit 8 forms an image on a recording medium P described later. The control unit 24 controls the operation of each unit of the image forming apparatus 10.

<Image forming unit>
[Toner image forming section]
The toner image forming unit 14 includes an exposure device 30, image forming units 40Y, 40M, 40C, and 40K, and an intermediate transfer unit 50. Here, yellow (Y), magenta (M), cyan (C), and black (K) are examples of toner colors.

  The image forming units 40Y, 40M, 40C, and 40K have substantially the same configuration except for the toner used. Therefore, in FIG. 1, the reference numerals of the respective parts constituting the image forming units 40M, 40C, and 40K are omitted.

<Exposure equipment>
The exposure apparatus 30 is disposed in a substantially central region when the image forming apparatus 10 is viewed from the front. The exposure device 30 emits a light beam based on the image signal sent from the control unit 24, and forms an electrostatic latent image on the outer peripheral surface of each of the photosensitive drums 42Y, 42M, 42C, and 42K described later. Yes. The image signal sent from the control unit 24 is an image signal processed by the image processing unit 246 described later. Here, the photosensitive drum 42 is an example of an image carrier.

  The light beams emitted from the exposure device 30 are incident on the outer peripheral surfaces of the respective photosensitive drums 42Y, 42M, 42C, and 42K with the same light amount. Then, this light beam is applied to the electrostatic latent image (one dot of the light beam described above) in the main scanning direction and the sub-scanning direction of the outer peripheral surface of each photosensitive drum 42Y, 42M, 42C, 42K based on the image signal. Latent images arranged in each direction) are formed. Here, the main scanning direction refers to the own axis direction in each of the photosensitive drums 42Y, 42M, 42C, and 42K. The sub-scanning direction is a direction orthogonal to the own axis direction.

<Image forming unit>
The image forming unit 40Y includes a photosensitive drum 42Y, a charging device 44Y, a developing device 46Y, and a removing device 48Y. Similarly, the image forming units 40M, 40C, and 40K remove the photosensitive drums 42M, 42C, and 42K, the charging devices 44M, 44C, and 44K, and the developing devices 46M, 46C, and 46K so as to correspond to the respective colors. Devices 48M, 48C and 48K. In the following description, for the image forming units 40Y, 40M, 40C, and 40K and the members constituting them, the subscripts Y, M, C, and the like are used when it is not necessary to distinguish the toner colors (Y, M, C, and K). K is omitted. Here, the developing device 46 is an example of a developing unit.

  In each of the image forming units 40Y, 40M, 40C, and 40K, yellow (Y), magenta (M), cyan (C), and black (K) colors are provided on the outer peripheral surfaces of the photosensitive drums 42Y, 42M, 42C, and 42K. A toner image is formed. In addition, the image forming units 40Y, 40M, 40C, and 40K are arranged in a state where the units are inclined and aligned with respect to the apparatus width direction as a whole (see FIG. 1).

(Photosensitive drum)
As shown in FIG. 1, the photosensitive drum 42 is formed in a cylindrical shape, and is driven to rotate around its own axis (in the direction of arrow R1 (see FIG. 1)) by a driving means (not shown). . The photosensitive drum 42 includes an aluminum base material and a photosensitive layer (not shown) formed on the base material in the order of an undercoat layer, a charge generation layer, and a charge transport layer.

(Charging device)
As shown in FIG. 1, the charging device 44 is disposed along the own axis direction (device depth direction) of the photosensitive drum 42. The charging device 44 includes a charging roll 440 and a cleaning roll 450. A voltage necessary for charging the outer peripheral surface of the photosensitive drum 42 is applied to the shaft (not shown) of the charging roll 440. The charging roll 440 charges the outer peripheral surface of the photosensitive drum 42 to a negative polarity. The cleaning roll 450 is configured to remove toner, paper dust, dust, and the like attached to the outer peripheral surface of the charging roll 440.

(Developer)
As shown in FIG. 1, the developing device 46 is disposed along the own axis direction of the photosensitive drum 42. The developing device 46 includes a toner supply body 46A that supplies toner to the outer peripheral surface of the photosensitive drum 42, a plurality of transport members 46B that transport the developer G including the toner T and the carrier CA to the toner supply body 46A, and the development device. And a toner density sensor 60 for detecting the density of the toner T in 46. The developing device 46 develops the electrostatic latent image formed on the outer peripheral surface of the photosensitive drum 42 with the toner T as a toner image, thereby forming a toner image on the outer peripheral surface of the photosensitive drum 42. . Further, the developing device 46 is supplied with the developer G from the supply mechanism 22 (see FIG. 2). Here, the developing device 46 is an example of a developing unit. The toner density sensor 60 is an example of a toner density measuring unit.

  The toner concentration sensor 60 detects and detects the magnetic permeability of the developer G in the developing device 46 using the fact that the magnetic permeability of the developer G including the toner T and the carrier CA changes according to the toner concentration. The toner concentration is calculated based on the result.

(Removal device)
The removal device 48 includes a blade 48 </ b> A that is disposed along the own axis direction of the photosensitive drum 42 and that contacts the outer peripheral surface of the photosensitive drum 42. The blade 48 </ b> A removes toner (primary transfer residual toner), paper dust, dust, and the like remaining on the outer peripheral surface of the photosensitive drum 42 without being primarily transferred to an intermediate transfer belt 52 described later, from the outer periphery of the photosensitive drum 42. It is designed to be removed from the surface.

<Intermediate transfer unit>
The intermediate transfer unit 50 includes an intermediate transfer belt 52, a plurality (four) of primary transfer rolls 54, opposing rolls 56, and secondary transfer rolls 58.

  The intermediate transfer belt 52 is an endless belt. A plurality (four) of primary transfer rolls 54 and counter rolls 56 are arranged so as to contact the inner peripheral surface of the intermediate transfer belt 52 (see FIG. 1). The four primary transfer rolls 54 are disposed so as to face the respective photosensitive drums 42Y, 42M, 42C, and 42K with the intermediate transfer belt 52 interposed therebetween. The primary transfer roll 54 applies a voltage necessary for primary transfer to transfer the toner images formed on the outer peripheral surfaces of the photosensitive drums 42Y, 42M, 42C, and 42K to the outer peripheral surface of the intermediate transfer belt 52. Primary transfer.

  The secondary transfer roll 58 is disposed so as to face the opposing roll 56 with the intermediate transfer belt 52 interposed therebetween. The secondary transfer roll 58 applies a voltage necessary for the secondary transfer, and secondarily transfers the toner image primarily transferred onto the outer peripheral surface of the intermediate transfer belt 52 onto the recording medium P. Yes.

[Replenishment mechanism]
The replenishing mechanisms 22Y, 22M, 22C, and 22K have a function of replenishing the developer G to the developing devices 46Y, 46M, 46C, and 46K. In the following description, the replenishing mechanisms 22Y, 22M, 22C, and 22K and the members constituting them will be subscripted Y, M, C, and K when it is not necessary to distinguish the toner colors (Y, M, C, and K). Is omitted.

  FIG. 2 is a schematic diagram illustrating the configuration of the replenishing mechanisms 22Y, 22M, 22C, and 22K. The replenishment mechanism 22Y includes a developer storage unit 220Y and a developer transport unit 222Y. An opening 224Y is formed on one end side of the developer transport part 222Y. The supply mechanism 22Y has a function of transporting the developer G stored in the developer storage unit 220Y from the opening 224Y by the developer transport unit 222Y and supplying the developer G to the developing device 46Y. Here, the developer container 220 is an example of a container.

  The developer accommodating portions 220Y, 220M, 220C, and 220K are arranged above the intermediate transfer unit 50 in a state of being aligned in the apparatus width direction (see FIG. 1). A developer G for replenishing the developing device 46 is accommodated in the developer accommodating portion 220.

  The developer transport unit 222 connects the developer storage unit 220 and the developing device 46 disposed below the developer storage unit 220. The developer transport unit 222 is connected to the developing device 46 through the opening 224. The developer transport unit 222 transports the developer G stored in the developer storage unit 220 to the developing device 46.

  As shown in FIG. 2, the developer transport units 222M, 222C, and 222K are arranged in relation to the arrangement of the developer storage units 220M, 220C, and 220K to which the developer transport units are connected, and the developing devices 46M, 46C, and 46K, respectively. It has a bent shape. The augers 220M1, 220C1, and 220K1 are provided in portions along the apparatus width direction of the developer transport portions 222M, 222C, and 222K. Thereby, in the developer transport sections 222M, 222C, and 222K, the developer G that has flowed in from the developer storage sections 220M, 220C, and 220K is transported to the bent portions of the developer transport sections 222M, 222C, and 222K. It has become. Further, the developer transport portions 222M, 222C, and 222K are portions along the apparatus height direction so that the developer G transported to the bent portion by gravity is transported to the openings 224M, 224C, and 224K. It has become.

  On the other hand, the developer transport section 222Y has a substantially straight shape along the apparatus height direction. Therefore, the developer transport unit 222Y transports the developer G to the opening 224Y by gravity.

  When the replenishment mechanism 22 receives a command to replenish the developer G to the developing device 46 by the control unit 24, the agitators 220Y2, 220M2, 220C2, and 220K2 in the developer storage unit 220 are driven by a motor (not shown). It has come to be. The replenishment mechanism 22 performs a replenishment operation to replenish the developer G to the developing device 46 at a predetermined replenishment speed while the motor is driven. The replenishment speed refers to the amount of developer G per unit time that is replenished from the developer storage unit 220 to the developing device 46 by the replenishment mechanism 22. The developer accommodating portion 220 can be replaced with the main body of the image forming apparatus 10.

[Transport section]
The transport unit 16 includes a delivery roll 16A, a plurality of transport roll pairs 16B, a reverse transport unit 16D, and a discharge roll 16E described later. The delivery roll 16A is configured to send the recording medium P stored in the medium storage unit 12 to the downstream side in the transport direction of the recording medium P from the discharge roll 16A. The plurality of transport roll pairs 16B are arranged along a transport path 16C through which the recording medium P sent out by the delivery roll 16A is transported. The plurality of transport roll pairs 16B transport the recording medium P sent out by the feed roll 16A to the facing position between the facing roll 56 and the secondary transfer roll 58 (secondary transfer position T2 (see FIG. 1)). It has become.

  Further, the transport unit 16 is provided with a reverse transport unit 16D that transports the recording medium P by reversing the front and back so that an image can be formed on both sides of the recording medium P. The reverse conveyance unit 16D is provided on the opposite side of the intermediate transfer unit 50 with the conveyance path 16C interposed therebetween when the image forming apparatus 10 is viewed from the front side. The reverse conveyance unit 16D switches back the recording medium P having the toner image fixed on the surface. Thereafter, the reverse conveying unit 16D conveys the recording medium P to the secondary transfer position T2 so that the back surface of the recording medium P faces the outer peripheral surface of the intermediate transfer belt 52.

[Fixing device]
The fixing device 18 includes a fixing roll 18A and a pressure roll 18B. The fixing device 18 is disposed downstream of the secondary transfer position T2 in the conveyance direction of the recording medium P (see FIG. 1). The fixing device 18 is configured to fix the toner image secondarily transferred to the recording medium P to the recording medium P. The fixing roll 18A is arranged on the recording medium P on the side where the toner image is transferred, and a halogen heater (not shown) is arranged on the inner peripheral surface side thereof. The pressure roll 18B pressurizes the recording medium P, which is transported through the transport path 16C and passes the position T3 (see FIG. 1) facing the fixing roll 18A, toward the fixing roll 18A.

[Discharge part]
The discharge unit 20 is formed downstream of the fixing device 18 in the conveyance direction of the recording medium P and on a part of the outer upper surface of the main body of the image forming apparatus 10. The recording medium P on which the toner image is fixed is discharged to the discharge unit 20 by a discharge roll 16E provided at a portion between the fixing device 18 and the discharge unit 20 in the conveyance path 16C.

<Control part>
As described above, the control unit 24 controls the operation of each unit of the image forming apparatus 10. FIG. 3 is a control block diagram illustrating a relationship between the control unit 24 and each unit of the image forming apparatus 10. The control unit 24 is connected to the operation display unit 240, the image processing unit 246, the image storage unit 244, the image forming unit 8, and the storage unit 248 via the bus 250.

  The operation display unit 240 (not shown in FIG. 1) is provided in a part of the exterior of the main body of the image forming apparatus 10 so that the state of the image forming apparatus 10 (for example, a paper jam or the like has occurred) can be displayed. It has become. Further, after the paper jam processing or the like is completed, the information can be transmitted to the control unit 24 via the bus 250. The operation display unit 240 can display (notify) that there is an abnormality as a result of an abnormality diagnosis of the replenishment mechanism 22 described later. Here, the operation display unit 240 is an example of a notification unit.

  The control unit 24 causes the image processing unit 246 to process an image signal transmitted to the image storage unit 244 from an external PC (not shown) or the like. Further, the control unit 24 operates the image forming unit 8 based on the image signal processed by the image processing unit 246.

  In the storage unit 248, a program for operating the image forming apparatus 10, a control program for the replenishment mechanism 22, and the like are stored in advance. In addition, the storage unit 248 is configured so that information processed by the control unit 24 is transmitted via the bus 250 and can be stored each time. The abnormality diagnosis program 300 of the replenishment mechanism 22 stored in the control unit 20 and the storage unit 248 is a main part of the present embodiment, and will be described later.

<Operation of Image Forming Apparatus>
Next, the operation of the image forming apparatus 10 will be described with reference to FIG.

  The control unit 24 operates the image forming apparatus 10 when an image signal is transmitted to the image storage unit 244. The control unit 24 converts this image signal into image data of each color of yellow (Y), magenta (M), cyan (C), and black (K). The image data of each color is output to the exposure apparatus 30.

  Subsequently, the light emitted from the exposure device 30 according to the image data of each color is incident on the outer peripheral surface of the photosensitive drum 42 charged by the charging device 44. Then, electrostatic latent images corresponding to the image data of the respective colors are formed on the outer peripheral surfaces of the photosensitive drums 42Y, 42M, 42C, and 42K.

  Further, the electrostatic latent images formed on the outer peripheral surfaces of the photosensitive drums 42Y, 42M, 42C, and 42K are developed as toner images of the respective colors by the developing devices 46Y, 46M, 46C, and 46K.

  The toner images of the respective colors on the outer peripheral surfaces of the photosensitive drums 42Y, 42M, 42C, and 42K are transferred to the outer peripheral surface of the intermediate transfer belt 52 by the primary transfer rolls 54 provided for the respective colors that the outer peripheral surfaces face each other. Primary transfer.

  On the other hand, the recording medium P has a medium accommodating portion so that the portion of the outer peripheral surface of the intermediate transfer belt 52 where the toner image is primarily transferred reaches the secondary transfer position T2 by rotating around. 12 is transported to the secondary transfer position T2. Then, the toner image primarily transferred onto the outer peripheral surface of the intermediate transfer belt 52 is secondarily transferred onto the recording medium P which is conveyed to the secondary transfer position T2 and passes therethrough.

  Subsequently, the recording medium P onto which the toner image has been transferred is conveyed toward the fixing device 18. In the fixing device 18, the toner image is heated and pressed by the fixing roll 18 </ b> A and the pressure roll 18 </ b> B and fixed on the recording medium P.

  The recording medium P on which the toner image is fixed is discharged to the discharge unit 20 and the image forming operation is completed.

  When forming images on both sides of the recording medium P, as shown in FIG. 1, the recording medium P is transported to the reversal transport unit 16D after the toner image is fixed on the surface by the fixing device 18. Then, the recording medium P having the toner image fixed on the surface is switched back by the reversing conveyance unit 16D. Thereafter, the toner image is secondarily transferred to the back surface of the recording medium P at the secondary transfer position T2, and the toner image secondarily transferred by the fixing device 18 is fixed. Finally, the recording medium P having the toner images fixed on both sides is discharged to the discharge unit 20 and the image forming operation is completed.

<Configuration of main parts>
Next, the configuration of the control unit 24 as an abnormality diagnosis device for the replenishment mechanism 22 will be described. First, the structure of the control part 24 as an estimation means is demonstrated based on FIG. Next, the structure of the control part 24 as a diagnostic means is demonstrated based on FIG.

<< Control section as estimation means >>
Figure 4 is an upper limit Y _U and the lower limit Y _L of the developer supply time Y for the pixel count cumulative value X according to the present embodiment, an example of a developer replenishing time Y of transition for the pixel count cumulative value X obtained and It is a graph which shows. FIG. 5 is a flowchart of the abnormal state estimation method of the supply mechanism 22 according to the present embodiment. The control unit 24 diagnoses an abnormal state of the supply mechanism 22 using an abnormality diagnosis program 300 of the supply mechanism 22 described later.

  The control unit 24 diagnoses an abnormal state of the replenishment mechanism 22 from the correlation between the pixel count accumulated value X of the output image and the developer replenishment time Y. Specifically, the control unit 24 estimates that there is a possibility of abnormality in the supply mechanism 22 from this correlation. Further, when it is estimated that there is a possibility of abnormality in the replenishment mechanism 22, the control unit 24 diagnoses whether or not the replenishment mechanism 22 is abnormal. The control unit 24 performs this diagnosis every time an image forming operation is performed on each recording medium P by the image forming apparatus 10 (before the image forming operation is performed). Here, the control unit 24 is an example of an estimation unit. The control unit 24 is an example of a diagnostic unit.

The pixel count cumulative value X of the output image (hereinafter referred to as cumulative value X) is a cumulative value of past pixel count values. That is, the cumulative value X is a value related to the total amount of toner T used by the developing device 46, which is obtained based on past image data. One pixel refers to one dot of a light beam incident on the outer peripheral surface of the photosensitive drum 42 by the exposure device 30 based on the image data output from the control unit 24. For example, in the case of an output image corresponding to 600 dpi in the main scanning direction and the sub-scanning direction, the exposure apparatus 30 emits a one-dot light beam to an area corresponding to about 42 × 60 μm ^{2 on} the outer peripheral surface of the photosensitive drum 42. . The pixel count value refers to the number of pixels of the light beam incident on the outer peripheral surface of the photosensitive drum 42 by the exposure device 30 when an image is formed on one recording medium P. One recording medium P is counted in terms of A4 size recording medium P.

  The developer replenishment time Y (hereinafter referred to as replenishment time Y) refers to the replenishment mechanism 22 replenishing in the past in order to replenish the developing device 46 with the developer G stored in the developer storage unit 220. This is the cumulative time during which the operation was performed (the cumulative time during which the agitator 220 was driven). In other words, the replenishment time Y is the total replenishment amount replenished from the replenishment mechanism 22 to the developing device 46 in the past. The replenishment time Y is measured by a timer 242 (see FIG. 3) and stored in the storage unit 248.

  The control unit 24 always rewrites and stores the accumulated value X, replenishment time Y data, and the number of recording media P on which image formation has been performed in the storage unit 248. Then, when the abnormality diagnosis of the replenishment mechanism 22 is performed next, the control unit 24 reads the accumulated value X and replenishment time Y data stored in the storage unit 248 from the storage unit 246 and performs this diagnosis. It has become.

Control unit 24, when the abnormality diagnosis of the supply mechanism 22, from the accumulated value X and the replenishing time Y data read out from the storage unit 246, so as to obtain the upper limit Y _U and the lower limit Y _L of replenishing time Y for the cumulative value X It has become. Then, the control unit 24, the upper limit _{Y U} and the lower limit _{Y L} of replenishing time Y for the cumulative value X, by the respective formulas (1) and (2), so that finding. Expressions (1) and (2) are stored in the storage unit 246 as part of the abnormality diagnosis program 300 of the replenishment mechanism 22.

When the actual replenishment time Y is larger than the upper limit Y _U of the replenishment time Y with respect to the accumulated value X (Y> Y _U ) or smaller than the lower limit Y _L (Y <Y _L ), the control unit 24 counters The count value is incremented by 1 to 400 and stored in the storage unit 246 (see determination step S130 and step S150 in FIG. 5). On the other hand, the control unit 24, the actual replenishing time Y is the upper limit _{Y U} below (Y ≦ _Y U) of the replenishment time Y for the cumulative value X, and, if more than the lower limit _{Y L} of (Y ≧ _{Y L)} (tolerance The count value of the counter 400 is initialized and stored in the storage unit 246 (see determination step S130 and step S140 in FIG. 5). The storage unit 248 includes counters 400 and 402 described later (see FIG. 1).

Equation _{(1) Y U = C 1U} · X + C 2U
Equation _{(2) Y L = C 1L} · X + C 2L

Constant C _1U is the slope when guiding the upper limit Y _U of the replenishment time Y for the cumulative value X obtained by the control unit 24. The constant _C2U is a Y intercept (offset value) in the Y-X coordinate representing the accumulated value X with respect to the replenishment time Y. The constant C _1L is an inclination when the upper limit Y _L of the replenishment time Y with respect to the cumulative value X obtained by the control unit 24 is derived. The constant _C2L is a Y intercept (offset value) in the Y-X coordinate representing the accumulated value X with respect to the replenishment time Y.

The constant C _1U and the constant C _1L are the volume in which the developer G (toner T) is accommodated in the developing device 46, the supply capability (supply speed) to the photosensitive drum 42 by the toner supply body 46A, and the developing device by the replenishment mechanism 22. It is determined in consideration of the replenishment ability (replenishment speed) of the developer G to 46 and the like. On the other hand, the constant C _2U and the constant C _2L are the developer replenishing operation for the developer transport unit 222 performed when the image forming apparatus 10 is installed (initial setting) and the developer G replenished to the developing device 46. Determined in consideration of the amount of

Figure 4 is a graph showing the upper limit Y _U and the lower limit Y _L of replenishing time Y for the cumulative value X, and an example of a replenishing time Y of transition for the cumulative value X obtained, the. In this graph, the case where C _1U is input as 0.5, C _2U as 75, C _1L as 0.3, and C _2L as −25 is shown in the equations (1) and (2).

When the control unit 24 performs the abnormality diagnosis of the supply mechanism 22, for example, when the accumulated value X obtained 200, replenishment time Y is 140, the upper limit _{Y U} of the replenishment time Y for the cumulative value X 175, cumulative the lower limit _{Y L} of replenishing time Y for values X becomes 35. In this case, the replenishment time Y (140) is smaller than the upper limit Y _U (175) of the replenishment time Y and larger than the lower limit Y _L (35). It is estimated that it is not abnormal. The control unit 24 stores the value of the counter 400 in the initial state (see step S140 in FIG. 5).

Further, when the control unit 24 performs this diagnosis, when the accumulated value X obtained 300, replenishment time Y is 280, the upper limit Y _U of the replenishment time Y for the cumulative value X 225, supplementation on the accumulated value X the lower limit _{Y L} time Y becomes 65. Then, since the replenishment time Y (280) in this case is longer than the upper limit Y _U (225) of the replenishment time Y, the control unit 24 causes the counter 400 to store the count value by one.

  Further, as a result of the diagnosis of the abnormal state of the replenishment mechanism 22 being performed a plurality of times, when the count value of the counter 400 reaches a predetermined threshold value T1, the control unit 24 serving as a diagnosis means Abnormal diagnosis to diagnose the presence or absence.

<< Control section as diagnostic means >>
Next, the structure of the control part 24 as a diagnostic means is demonstrated based on FIG. FIG. 6 shows a specific flow in step S170 of FIG.

  The control unit 24 can determine whether the remaining amount of the developer G in the developer storage unit 220 is sufficient. As an example, an amount by which the remaining amount of the developer G in the developer container 220 becomes 10% of the capacity is set as the threshold value N for this determination. It is assumed that the time required for the replenishment operation for replenishing all the developer G in the developer accommodating portion 220 into the developing device 46 is 1500 seconds. Then, if the total replenishment time required for the replenishment operation for replenishing developer G into the developing device 46 (the time during which the replenishment operation has been performed in the past) is less than 1350 seconds, the control unit 24 controls the developer storage unit. It is determined that the remaining amount of developer G in 220 is sufficient. Here, the above-described threshold value N for the determination is an example of a predetermined minimum remaining amount.

  On the other hand, when the control unit 24 determines that the remaining amount of the developer G in the developer storage unit 220 is not sufficient, the diagnosis of whether or not the replenishment mechanism 22 is abnormal is terminated.

  Further, when the control unit 24 determines that the remaining amount of the developer G in the developer storage unit 220 is sufficient, the control unit 24 measures the toner concentration in the developing device 46 using the toner concentration sensor 60. ing. Then, the control unit 24 determines that the difference between the measurement result by the toner density sensor 60 and the target value M of the toner density determined according to the cumulative value X and the replenishment time Y (hereinafter referred to as toner density difference) is the cumulative value X and the cumulative value X. It is determined whether or not the deviation value T2-1 determined according to the replenishment time Y is exceeded. Further, in addition to determining whether the deviation value T2-1 is exceeded, the control unit 24 also determines whether the cumulative value X of the image output in the past is an output of a high image density image. (See step S210 in FIG. 6). Here, the toner density difference is an absolute value.

  Here, the target value M of the toner density refers to the environment (temperature, humidity, etc.) in the image forming apparatus 10, the image density of the output image, the replenishment mechanism 22, the developer G, the developing device 46, the photosensitive drum 42, and the like. It is used to suppress the density fluctuation of the output image due to the cause of deterioration. In the present embodiment, the detection result by the toner density sensor 60 for the developer G in the developing device 46 replenished at the time of product manufacture is used as a reference, and the correction is performed with respect to this reference in consideration of the above factors. The density target value M is used. Further, the deviation value T2-1 is determined in consideration of the detection error of the toner density sensor 60, and is used to detect a fluctuation exceeding the detection error.

  Further, the determination as to whether the accumulated value X is an output of a high image density image is performed as follows, for example. The control unit 24 obtains an average pixel count value of the output image per recording medium from data such as the accumulated value X and the total number of output recording media P. For example, the control unit 24 sets the pixel count value determined to be a high image density image to 25% or more. When the pixel density for the recording medium P is 100% and the pixel count value is 4000, the control unit 24 sets the average image density to 5% if the pixel count value output in the past is 200. ing. If the average pixel count value of the output image per recording medium of the image output in the past is 1000 or more, the average image density is 25%, and it is determined that the output is a high image density image. . Note that the average pixel count value of the output image per recording medium may be obtained from data in a past certain period (such as a period during which the most recent image forming operation has been performed).

  When the control unit 24 determines that the measurement result of the toner density sensor 60 exceeds the deviation value T2-1 and that the image output in the past is not the output of the high image density image, the control unit 24 The count value is incremented by 1 and stored (see steps S210 and S230 in FIG. 6). Here, this count value is an example of the number of times of satisfaction.

  Furthermore, the control unit 24 determines whether or not the count value of the counter 402 stored by incrementing by 1 has reached a predetermined threshold value T2-2 (see step S240 in FIG. 6). If the count value has reached the threshold value T2-2, it is determined that there is an abnormality in the replenishment mechanism 22, and if it has not reached, it is not determined that there is an abnormality, and whether or not there is an abnormality in the replenishment mechanism 22 is diagnosed. Is supposed to end.

  On the other hand, when the control unit 24 determines that the measurement result of the toner density sensor 60 does not exceed the divergence value T2-2 or that the image output in the past is the output of the high image density image, the counter 24 The count value of 402 is set to an initial state, and this diagnosis is finished (see step S220 in FIG. 6).

  The abnormality diagnosis of the supply mechanism 22 is performed independently for the supply mechanisms 22Y, 22M, 22C, and 22K.

<Operation of First Embodiment>
Next, the effect | action of 1st Embodiment is demonstrated based on FIG.5 and FIG.6. First, it demonstrates based on FIG.

  Before the image forming operation by the image forming apparatus 10 is started and the outer peripheral surface of the photosensitive drum 42 is charged by the charging device 44, abnormality diagnosis of the replenishment mechanism 22 is started.

  When the abnormality diagnosis of the replenishment mechanism 22 is started, the cumulative value X is obtained by the control unit 24 in step S100.

  Next, the replenishment time Y is calculated | required by the control part 24 in step S110.

Next, in step S120, based on the accumulated value X obtained in step S100, is the lower limit _{Y L} max _{Y U} a is the formula (1) and replenishment time Y for the cumulative value X of the replenishment time Y for the cumulative value X Equation (2) is obtained.

Next, at decision step S130, the replenishment time Y obtained in S110, S120 in obtained than the upper limit _{Y U} of the replenishment time Y for the cumulative value X, and, if equal to or greater than the lower limit _{Y L} is determined (see FIG. 5) .

If the replenishment time Y determined in S110 is within the allowable range in the determination step S130, the count value of the counter 400 is set to the initial state and stored in the storage unit 246 in step S140. Then, the abnormality diagnosis of the replenishment mechanism 22 ends.

If the replenishment time Y determined in S110 is outside the allowable range in the determination step S130, the value of the counter 400 is incremented by 1 in step S150 by the control unit 24 as the estimation unit and stored in the storage unit 246. Is done.

  In determination step S160, it is determined whether the count value of the counter 400 incremented by 1 in step S150 has reached a predetermined threshold value T1.

  When it is determined in the determination step S160 that the value of the counter 400 has reached a predetermined threshold value T1, in step S170, the control unit 24 as a diagnosis unit starts diagnosing whether the replenishment mechanism 22 is abnormal. Is done. The diagnosis of whether or not the supply mechanism 22 is abnormal will be described later.

  Further, when it is determined in the determination step S160 that the count value of the counter 400 has not reached the predetermined threshold value T1, the control unit 24 does not perform the diagnosis of the abnormality of the replenishment mechanism 22, and the diagnosis ends. To do. In this case, the count value of the counter 400 is carried over until the next diagnosis.

  As described above, the control unit 24 according to the present embodiment estimates whether or not the replenishment mechanism 22 may be abnormal based on the correlation between the accumulated value X and the replenishment time Y. In addition, the supply mechanism 22 is diagnosed as to whether there is an abnormality.

  Therefore, according to the control unit 24 of the present embodiment, the abnormality of the replenishment mechanism is changed to the developer replenishment and consumption status as compared with the abnormality diagnosis without being based on the correlation between the accumulated value X and the replenishment time Y. The diagnosis can be made appropriately.

  Next, as a comparative example (Comparative Example 1), it is assumed that the replenishment mechanism is diagnosed for abnormality when the replenishment time Y is outside the allowable range of the cumulative value X. In this case, if the replenishment time Y is outside the allowable range of the cumulative value X, it is immediately estimated that there is a possibility of abnormality of the replenishment mechanism, and the process proceeds to diagnosis of the presence or absence of abnormality.

  On the other hand, in the control part 24 of this Embodiment, the frequency | count that the replenishment time Y becomes out of the tolerance | permissible_range of the cumulative value X is counted. Then, the control unit 24 estimates that there is a possibility of abnormality in the replenishment mechanism 22 until the number of times reaches a predetermined threshold value T1, and shifts to diagnosis of whether or not the replenishment mechanism 22 is abnormal.

  Therefore, according to the control unit 24 of the present embodiment, there is a possibility that the replenishment mechanism 22 may have an abnormality in the replenishment mechanism appropriately according to the replenishment and consumption status of the developer as compared with the case of the first comparative example. Presumed.

  Next, as a comparative example (comparative example 2), it is assumed that when the replenishment time Y is within the allowable range of the cumulative value X, the number of times that the replenishment time Y has been outside the allowable range in the past does not become the initial state. In this case, when the replenishment time Y becomes out of the allowable range in the abnormality diagnosis after the next time and the number of times that the replenishment time Y is out of the allowable range reaches a predetermined threshold value, the control unit 24 shifts to diagnosis of whether or not the replenishment mechanism is abnormal. To do.

  On the other hand, in the control part 24 of this Embodiment, when the replenishment time Y becomes in the tolerance | permissible_range of the cumulative value X, the frequency | count that became out of tolerance in the past is made into an initial state. For example, since the output of a high image density image has continued, the amount of developer consumption is large, and if it falls outside the allowable range once but returns to the allowable range again, the number of times that it has been out of the allowable range in the past is the initial state. It is said. That is, the next abnormality diagnosis is performed regardless of the past developer supply and consumption conditions. Then, even if it is outside the allowable range in the previous abnormality diagnosis, if it is within the allowable range in the current abnormality diagnosis, it is regarded as not an abnormal state.

  Therefore, according to the control part 24 of this Embodiment, compared with the case of the comparative example 2, abnormality of a replenishment mechanism can be diagnosed appropriately according to a developer replenishment and consumption situation.

  Further, since the control unit 24 of the present embodiment does not need to use means such as a sensor for measuring the number of rotations such as an auger or agitator of the developer transport unit, cost reduction and space saving are realized accordingly. it can. In addition, since the control unit 24 according to the present embodiment does not need to use means such as the sensor, the control unit 24 is not affected by variations in the expected accuracy of the remaining amount of the developer G caused by the sensor in the first place.

  Next, a description will be given based on FIG.

  In the diagnosis of whether or not the replenishment mechanism 22 is abnormal, it is determined whether or not the remaining amount of the developer G in the developer accommodating portion 220 is sufficient based on the total replenishment time of the replenishment operation of the replenishment mechanism 22 as in determination step S200. . If it is determined that the remaining amount of the developer G is not sufficient, this diagnosis is terminated.

  When it is determined that the remaining amount of the developer G is sufficient, the difference between the measurement result of the toner density sensor 60 and the target value M exceeds the deviation value T2-1 as in determination step S210, and A condition that an image output in the past is not an output of a high image density image (hereinafter referred to as condition A) is determined.

  When the condition A is not satisfied, the counter 402 is initialized as in step S220, and this diagnosis is completed.

  On the other hand, when the condition A is satisfied, the count value of the counter 402 is incremented by 1 as in step S230. Then, as in determination step S240, it is determined whether the count value of the counter 402 increased by 1 has reached a predetermined threshold value T2-2.

  If the value of the counter 402 has reached a predetermined threshold value T2-2, it is determined that there is an abnormality in the replenishment mechanism 22 as shown in step S250, and this diagnosis is terminated. On the other hand, when the value of the counter 402 does not reach the predetermined threshold value T2-2, it is determined that the replenishment mechanism 22 has no abnormality, and this diagnosis is terminated.

  As described above, the control unit 24 according to the present embodiment first determines the total replenishment required for the replenishment operation for replenishing the developer G into the developing device 46 when diagnosing whether or not the replenishment mechanism 22 is abnormal. From the time, it is determined whether the remaining amount of the developer G in the developer container 220 is sufficient. Then, when it is determined that the remaining amount of the developer G is not sufficient, this diagnosis ends.

  Here, as a comparative example (comparative example 3), a case is assumed in which it is determined that the supply mechanism 22 is abnormal if the condition is satisfied in the determination step S200 of FIG. In this case, it is not determined whether the toner T (or developer G) is larger than the threshold in the developing device. Further, it is not determined whether there is a suspicion that the follow-up performance of the developer G replenishment due to the output of the high image density image is lowered.

  In contrast, the control unit 24 of the present embodiment determines whether the condition A is satisfied.

  Therefore, according to the control part 24 of this Embodiment, compared with the case of the comparative example 3, abnormality of a replenishment mechanism can be diagnosed appropriately according to the supply and consumption status of a developer.

  Next, as a comparative example (comparative example 4), when the condition A is satisfied, a case is assumed in which it is diagnosed that there is an abnormality in the replenishment mechanism regardless of the number of times. In this case, if the condition A is satisfied, it is immediately diagnosed that there is an abnormality in the supply mechanism.

  On the other hand, in the control unit 24 of the present embodiment, the number of times when the condition A is satisfied is counted. Only when the number of times reaches a predetermined threshold value T2-2, it is diagnosed that there is an abnormality in the replenishment mechanism 22.

  Therefore, according to the control unit 24 of the present embodiment, the abnormality of the replenishment mechanism can be appropriately diagnosed according to the replenishment and consumption status of the developer as compared with the case of the comparative example 4.

  As a comparative example (Comparative Example 5), it is assumed that the condition A is not satisfied and the number of times the condition A has been satisfied in the past does not become the initial state. In this case, when the condition A is satisfied in the subsequent abnormality diagnosis and reaches a predetermined threshold value, it is diagnosed that there is an abnormality in the replenishment mechanism.

  On the other hand, in the control unit 24 of the present embodiment, when the condition A is not satisfied, the number of times that the condition A has been satisfied in the past is set as the initial state. That is, the next abnormality diagnosis is performed regardless of the past supply and consumption of the developer. Then, even if the condition A is satisfied in the previous abnormality diagnosis, if the condition A is not satisfied in the current abnormality diagnosis, it is regarded as not an abnormal state.

  Therefore, according to the control unit 24 of the present embodiment, the abnormality of the replenishment mechanism can be appropriately diagnosed according to the replenishment and consumption status of the developer as compared with the case of the comparative example 5.

  Further, according to the image forming apparatus 10 of the present embodiment, as a result of performing an abnormality diagnosis based on the correlation between the accumulated pixel count value of the output image and the developer replenishment time, at least there is no notification that there is an abnormality. In comparison, if there is an abnormality as a result of the abnormality diagnosis of the replenishment mechanism 22 based on the correlation between the accumulated value X and the replenishment time Y, it can be notified that there is an abnormality.

  Further, according to the abnormality diagnosis program for the replenishment mechanism of the present embodiment, compared with the control unit (computer) that performs abnormality diagnosis without being based on the correlation between the accumulated pixel count value of the output image and the developer replenishment time. The control unit 24 can function as the estimation unit and the determination unit.

<< Modification of First Embodiment >>
<Configuration of Modification of First Embodiment>
Next, the configuration of the control unit 24 as an abnormality diagnosis device for the replenishment mechanism 22 in a modification of the first embodiment will be described with reference to FIG. In this case, the control unit 24 can diagnose an abnormal state of the supply mechanism 22 using an abnormality diagnosis program 302 of the supply mechanism 22 described later. The abnormality diagnosis program 304 of the replenishment mechanism 22 is stored in the storage unit 248. FIG. 7 is a flowchart of the abnormality diagnosis method for the supply mechanism 22 according to the present embodiment. Hereinafter, a description will be given focusing on the parts different from the above-described embodiment. Note that the same parts (parts and the like) as those of the above-described embodiment will be described using the same reference numerals for the same parts and the like.

  In the determination step S310 of this modification, unlike the determination step S210 of the second embodiment, it is not determined whether the accumulated value X is an output of a high image density image.

  When the replenishment speed of the developer G into the developing device 46 by the replenishment mechanism 22 is sufficient, or when the replenishment amount is sufficient (even if a high image density image is output, a high image is not replenished with the developer G). This modification is applied to the case where there is followability to the density image output. The present modification is also applied to a case where a reserve tank (sub tank) that temporarily stores the developer G is provided between the developer storage unit 220 and the developing device 64. That is, in such a case, it is not necessary to determine whether the accumulated value X is an output of a high image density image.

<Operation of Modified Example of First Embodiment>
According to the control unit 24 of the present embodiment, a toner concentration for measuring the toner concentration in the developing unit when the remaining amount of the developer estimated from the developer replenishment time is larger than a predetermined minimum remaining amount. The third number of times satisfying the condition that the difference between the measurement result of the measuring means and the target value of the predetermined toner density exceeds the deviation value is counted, and the third number reaches a predetermined threshold value. When compared with the case where it is not diagnosed that there is an abnormality in the replenishment mechanism, the abnormality of the replenishment mechanism 22 can be appropriately diagnosed according to the supply and consumption status of the developer.
The operation of this modification is the same as that of the above-described embodiment.

<< Second Embodiment >>
<Configuration of Second Embodiment>
Next, the configuration of the control unit 24 as an abnormality diagnosis device for the replenishment mechanism 22 in the second embodiment will be described with reference to FIGS. 8 and 9. FIG. 8 is a flowchart of the abnormality diagnosis method for the supply mechanism 22 according to the present embodiment. FIG. 9 is a table showing the relationship between the average image density used in the abnormality diagnosis method of the replenishment mechanism and the density average for each category. Hereinafter, a description will be given focusing on the parts different from the above-described embodiment. Note that the same parts (parts and the like) as those of the above-described embodiment will be described using the same reference numerals for the same parts and the like.

  The control unit 24 can diagnose an abnormal state of the supply mechanism 22 using the abnormality diagnosis program 304 of the supply mechanism 22. The abnormality diagnosis program 304 of the replenishment mechanism 22 is stored in the storage unit 248. The storage unit 246 is provided with a counter 404.

  The control unit 24 of the present embodiment shows a flow after the start of diagnosis of the presence or absence of abnormality of the replenishment mechanism 22 in step S170 (see FIG. 5) in the above-described embodiment.

  The control unit 24 classifies the average image density of the output image into four categories (see FIG. 9), and obtains an average value of toner density differences (referred to as Δ density average) (step in FIG. 8). (See S410). As shown in FIG. 9, these four categories are categories 1 to 4, respectively, with an average image density of 10% or less, 10% or more, 20% or less, 20% or more, 70% or less, or 70% or more. Largely classified as 100% or less. Further, as shown in FIG. 9, the control unit 24 obtains the difference of Δ density averages of other categories on the basis of the Δ density average when the average image density is 0 to 10% (FIG. 9). 8 step S420). Here, the Δ concentration average is an example of a category average value.

  Specifically, the control unit 24 always classifies each recording medium P into the above four categories based on the pixel count value of the output image of the recording medium P on which the image has been formed, and stores it for each recording medium P. From the accumulated value X and replenishment time Y data, the Δ concentration average is obtained. Note that the average pixel count value of the output image per recording medium may be obtained from data in a past certain period (such as a period during which the most recent image forming operation has been performed).

Then, the control unit 24 determines that any one of the differences of the Δ density averages of the two categories (category 3 and 4) on the higher average image density side is equal to or less than a predetermined threshold T3-1 (determination in FIG. 8). In step S430), it is determined that there is a possibility that the follow-up capability of the replenishment mechanism 22 to the high image density image output is deteriorated. In this case, it is determined whether any one of the Δ density averages of the two categories (see categories 1 and 2 in FIG. 9) on the side where the average image density is small is equal to or less than a predetermined threshold T3-2. (Refer to judgment step S440 in FIG. 8). Here, the difference in Δ density average is an example of a difference in category average value.

  When none of the conditions in the determination step S440 is satisfied, the control unit 24 sets the count value of the counter 404 to an initial state and ends this diagnosis. On the other hand, if the condition of the determination step S440 is satisfied, the control unit 24 increases the count value of the counter 404 by 1, and if the value has reached a predetermined threshold value T3-3, This diagnosis is terminated (see steps S450 to S480 in FIG. 8). Here, this count value is an example of the number of times of satisfaction.

  The control unit 24 determines that any one of the differences of the Δ density average of the two categories (category 3 and 4) on the higher average image density side is not less than or equal to a predetermined threshold T3-1 (determination step S430 in FIG. 8). Reference), it is determined that there is no suspicion that the follow-up performance of the replenishment mechanism 22 with respect to the high image density image output is lowered. In this case, the control unit 24 performs an abnormality diagnosis of the replenishment mechanism 22 according to the above-described flow of FIG. 7 (modified example of the second embodiment).

  Here, the abnormality diagnosis of the replenishment mechanism 22 by the control unit 24 will be described in more detail with reference to FIGS. For example, when the difference of the Δ density average is −0.7% or less, the threshold T3-1 is set to determine that there is a suspicion that the followability of the high image density density image is lowered. Then, as shown in FIG. 9, in category 4 (average image density greater than 70% and less than 100%), the difference in Δ density average is lower than the threshold value T3-1. In this case, the control unit 24 performs an abnormality diagnosis of the replenishment mechanism 22 according to the flow after the determination step S440 shown in FIG.

<Operation of Second Embodiment>
Next, the effect | action of this Embodiment is demonstrated based on FIG.

  In the diagnosis of whether or not the replenishment mechanism 22 is abnormal, it is determined whether or not the remaining amount of the developer G in the developer accommodating portion 220 is sufficient based on the total replenishment time of the replenishment operation of the replenishment mechanism 22 as in step S400. If it is determined that the remaining amount of the developer G is not sufficient, this diagnosis is terminated.

  If it is determined that the remaining amount of developer G is sufficient, an average Δ density for each category is obtained in step S410. In step S420, the difference of each Δ density average with respect to the Δ density average reference is also obtained.

  Next, in determination step S430, it is determined whether at least one of the differences in the Δ density average of the two categories (category 3 and 4) on the higher average image density side is equal to or less than a predetermined threshold T3-1. Is done.

  If this condition is not satisfied, an abnormality diagnosis of the replenishment mechanism 22 is performed according to determination step S310 and subsequent steps. Note that the flow after step S310 follows the flow after determination step S440 shown in FIG.

  On the other hand, if this condition is satisfied, it is determined that there is a suspicion that the replenishment mechanism 22 is less likely to follow the high image density image output. Then, in a determination step S440, it is determined whether any one of the Δ density averages of the two categories (FIGS. 1 and 2) on the side having a smaller average image density is equal to or less than a predetermined threshold value T3-2.

  If none of the conditions in the determination step S440 is satisfied, the counter 404 is set to an initial state in step S490, and this diagnosis ends. In this case, although the condition of the determination step S430 is satisfied, the Δ density average of categories 1 and 2 that are relatively low image density image outputs is larger than the determined threshold value T3-2. As long as the image density image is output, it is not recognized that the developer G replenishment followability is abnormal. That is, it can be determined that the followability is lowered in the high image density image output.

  On the other hand, if the condition of determination step S440 is satisfied, the count value of the counter 404 is incremented by 1 in step S450, and if the count value reaches a predetermined threshold value T3-3 in determination step S460, replenishment is performed. The diagnosis is terminated when it is determined that the mechanism 22 is abnormal.

  As described above, the control unit 24 according to the present embodiment determines whether any one of the Δ density average differences of the categories 3 and 4 is less than the threshold value T3-1 (determination step S430).

  Here, in step S430, category 1 is used as a reference for obtaining the difference in Δ density average because category 1 has the lowest average image density compared to other categories, and therefore, the value of the Δ density average of category 1 is used. This is because the variation in is considered small with respect to other categories.

  Further, in step S430, the determination with respect to the difference with respect to the reference is that the Δ density average is obtained even in a state where the replenishment ability of the developer G is chronically decreased due to the variation (so-called individual variation) for each replenishment mechanism 22. This is for reliably detecting a decrease in followability in high image density image output as compared with the case of using. Here, the state in which the replenishment ability of the developer G is chronically reduced means that the replenishment ability of the developer G is lower than the design value due to individual variation of the replenishment mechanism 22, and a high image density image. A state in which not only the output but also the low image density image output cannot be followed.

  Specifically, when the condition of the determination step S430 is satisfied, it is determined that there is a suspicion that the followability of the high image density image output is lowered. Thereafter, the determination in determination step S440 is performed. Here, the conditions of the determination step S430 and the determination step S440 are satisfied, the count value of the counter 404 is incremented by 1 in step S450, and the count value reaches a predetermined threshold value T3-3 in the determination step S460. Think if you are. In this case, it is determined that the followability of the high image density image output is abnormal and the followability of the low image density image output is also abnormal. That is, it is determined that the developer G replenishment ability is chronically reduced. That is, whether or not the developer G replenishment ability is chronically reduced by performing the determination step S440 when this condition is satisfied after the determination based on the difference in the Δ density average is performed in the determination step S430. In the case of high image density image output, it can be determined whether the followability is not satisfied.

  Therefore, according to the control unit 24 of the present embodiment, a suspicion of a decrease in the followability of the high image density image output is accurately determined as compared with the case where the determination is made based on the Δ density average in the determination step S430.

  Further, if the condition of the determination step S430 is satisfied, it is determined that there is a suspicion that the followability of the high image density image output is lowered, and then, in the determination step S440, the categories 1 and 2 that are relatively low image density image outputs. It is determined whether the average Δ concentration is equal to or less than a predetermined threshold value T3-2. If the condition of determination step S440 is satisfied, the count value of the counter 404 is incremented by 1 in step S450. When the count value of the counter 404 reaches a predetermined threshold value T3-3, the output of the toner density sensor 60 is reduced regardless of the image density, and if the supply mechanism 22 is abnormal in step S480. To be judged.

  Therefore, according to the control unit 24 of the present embodiment, after the determination step S430, an abnormality of the replenishment mechanism is appropriately diagnosed in accordance with the developer replenishment and consumption conditions, compared with not performing the determination step S440. be able to.

  Note that the threshold T3-1 for the difference in Δ density average or the threshold T3-2 for the Δ density average may be set for each category. Thereby, the degree of an abnormal state can be classified according to each threshold T3-1 and T3-2. Here, the level of the abnormal state is a classification of the abnormal state with respect to the estimated remaining amount of the developer G. For example, when the remaining amount of the developer G is estimated to be large but in an abnormal state, the developer transporting part 222 is clogged with the developer G.

  Other operations are the same as those of the above-described embodiment.

  As described above, the present invention has been described in detail with respect to specific embodiments. However, the present invention is not limited to the above-described embodiments, and various other embodiments are within the scope of the present invention. Is possible.

  For example, in the first embodiment, the control unit 24 obtains the replenishment time Y after obtaining the cumulative value X as shown in FIG. However, it is sufficient that the correlation between the cumulative value X and the replenishment time Y can be obtained, and it may be obtained in reverse or simultaneously.

In the first embodiment, the control unit 24, as in step S120 of FIG. 5, seeking the maximum Y _U and the lower limit Y _L of replenishing time Y for the cumulative value X. However, since it is only necessary to know the correlation between the cumulative value X and the replenishment time Y, the upper limit and the lower limit of the cumulative value X with respect to the replenishment time Y are obtained, and in the determination step S130, the cumulative value X is It may be judged whether it is within.

  Further, the threshold value T1 in the first embodiment is not particularly illustrated, but may be set to 1.

  In the second embodiment, it may be determined that there is an abnormality in the replenishment mechanism 22 when the condition of step S210 is satisfied without determining whether the counter 402 has exceeded a predetermined threshold T2-2. .

  In the second embodiment, information for estimating the replenishment amount of the developer G may be used to determine the remaining amount of the developer G. For example, the pixel count cumulative value X may be used, or the drive rotation speed of the auger 222 in the developer supply mechanism may be used.

  In the second embodiment, whether the output is a high image density image may be determined according to the high image density followability of the replenishment amount of the developer G.

  Further, in the second embodiment, a plurality of threshold values may be provided for the determination with respect to the predetermined deviation value T2-1 of the measurement result of the toner density sensor 60. In this case, the severity of the abnormal state (failure) can be defined according to the deviation value T2-1. When the threshold value 2 (> threshold value 1) is set to a threshold value that is larger than the deviation value T2-1, a warning is given if the threshold value 1 is exceeded, and a notification that service support is required if the threshold value 2 is exceeded. You may do.

  In the second embodiment, the determination with respect to the predetermined divergence value T2-1 of the measurement result of the toner density sensor 60 only needs to be able to detect a decrease in toner density in the developing device 46, and the intermediate transfer member. The result obtained by detecting the density detection patch prepared on the fixed potential condition with the optical toner density sensor may be used.

  In addition, although notification that the replenishment mechanism 22 is abnormal is performed by displaying on the operation display unit 240, notification may be performed by a method (sound or the like) other than display. Furthermore, you may notify a service person, a customer center, etc. via a network etc. that it is abnormal, without using the operation display part 240. FIG.

  In the second embodiment, the determination step S410 is performed for categories 3 and 4 having a relatively high average image density among the categories 1 to 4. On the other hand, after categorizing the categories, the category in which the difference in the Δ density average is lower than the threshold value may be selected, and the determination step S410 may be performed.

  Further, the abnormality diagnosis programs 300, 302, 304, and 306 of the replenishment mechanism 22 are stored in the storage unit 248. However, the abnormality diagnosis program stored in an information storage medium such as a CD-ROM is installed. May be. Further, the abnormality diagnosis program may be installed via a network.

DESCRIPTION OF SYMBOLS 10 Image forming apparatus 14 Toner image forming part 22 Replenishment mechanism 24 Control part (an example of an estimation means, an example of a diagnostic means, an example of the abnormality diagnosis apparatus of a replenishment mechanism, an example of a computer)
42 Photosensitive drum (an example of an image carrier)
46 Development device (example of development unit)
60 Toner density sensor (an example of toner density measuring means)
220 developer container (an example of a container)
300, 302, 304 Abnormality diagnosis program G Developer N threshold (an example of a predetermined minimum remaining amount)
M Target value P Recording medium T Toner T2-2, T3-3 Threshold value T2-1 Deviation value X Pixel count accumulated value Y Replenishment time (an example of accumulated developer replenishment time)

Claims (9)

An estimation means for estimating that there is a possibility of abnormality in the replenishment mechanism, based on a cumulative pixel count value of the output image and a developer replenishment time by a replenishment mechanism that replenishes the developer with developer.
A diagnostic means for diagnosing the presence or absence of an abnormality in the replenishment mechanism when the estimation means estimates that there is a possibility of an abnormality in the replenishment mechanism;
An abnormality diagnosis device for a replenishment mechanism comprising: The estimation means includes
Counting the number of times when the developer replenishment time is greater than the upper limit of the developer replenishment time with respect to the pixel count cumulative value, or the number of times when it is less than the lower limit,
When the number of times reaches a predetermined threshold, it is estimated that the supply mechanism may be abnormal.
The abnormality diagnosis device for a supply mechanism according to claim 1. The estimation means includes
When the developer replenishment time is less than or equal to the upper limit of the developer replenishment time with respect to the pixel count cumulative value, and greater than or equal to the lower limit ,
Initializing the number of times,
The abnormality diagnosis device for a supply mechanism according to claim 2. The diagnostic means includes
The remaining amount of the developer in the storage unit that stores the developer to be replenished to the developing unit is greater than a predetermined minimum remaining amount,
The difference between the measurement result of the toner density measuring means for measuring the toner density in the developing unit and the target value determined in accordance with the pixel count cumulative value and the developer supply time is the pixel count cumulative value and the developer supply time. The number of times of satisfaction satisfying the condition that the deviation value determined in accordance with the condition is exceeded and that the average pixel count value of the output image per recording medium does not exceed the predetermined pixel count value is counted. , When the number of fulfillment reaches a predetermined threshold,
Diagnosing an abnormality in the replenishment mechanism,
The abnormality diagnosis device for a supply mechanism according to any one of claims 1 to 3. The diagnostic means includes
The remaining amount of the developer in the storage unit that stores the developer to be replenished to the developing unit is greater than a predetermined minimum remaining amount,
The difference between the measurement result of the toner density measuring means for measuring the toner density in the developing unit and the target value determined in accordance with the pixel count cumulative value and the developer supply time is the pixel count cumulative value and the developer supply time. When the number of fulfillment satisfying the condition of exceeding the divergence value determined according to, and the fulfillment count reaches a predetermined threshold,
Diagnosing an abnormality in the replenishment mechanism,
The abnormality diagnosis device for a supply mechanism according to any one of claims 1 to 3. The diagnostic means includes
The remaining amount of the developer in the storage unit that stores the developer to be replenished to the developing unit is greater than a predetermined minimum remaining amount,
Classify into multiple categories according to the average image density for each recording medium,
For each category, a category average value that is an average value of a difference between a measurement result of the toner density measuring unit and a target value determined according to the pixel count cumulative value and the developer replenishment time; and among the plurality of categories A difference of a category average value that is a difference between the average value of one predetermined category and the average value of another category;
A category having a relatively low average image density among the plurality of categories when a difference in the category average value is equal to or less than a predetermined threshold with respect to a category having a relatively high average image density among the other categories. On the other hand, the number of fulfillment satisfying that the category average value is less than or equal to a predetermined threshold is counted,
Diagnosing that there is an abnormality in the replenishment mechanism when the number of times of satisfaction reaches a predetermined threshold;
The abnormality diagnosis device for a supply mechanism according to claim 4 or 5. The diagnostic means includes
If the condition is not satisfied, the satisfaction count is set to an initial state.
The abnormality diagnosis device for a supply mechanism according to any one of claims 4 to 6. The developing unit;
The replenishment mechanism;
The abnormality diagnosis device for a supply mechanism according to any one of claims 1 to 7, which performs abnormality diagnosis of the supply mechanism;
An image forming unit that forms an image on a recording medium using a developer supplied from the developing unit;
As a result of abnormality diagnosis of the replenishment mechanism, notification means for notifying that there is at least an abnormality,
An image forming apparatus. Computer
The estimation means according to any one of claims 1 to 7, and
The diagnostic means according to any one of claims 1 to 7,
Abnormality diagnosis program for replenishment mechanism to function as

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