JP2015001627A - Toner deterioration prediction method, toner deterioration prediction device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately predict a degree of deterioration of toner by using a conventionally acquired signal and without adding a new configuration and extra cost.SOLUTION: A toner deterioration estimating method for estimating a degree of deterioration of the toner of a two-component developer comprises: a step S1 in which a target development γ value is set by a target development γ value setting means, which sets the target development γ value; a step S2 in which a current development γ value is calculated by a current development γ value calculating means, which calculates the current development γ value; a step S3 in which the Δ development γ value is calculated by a Δ development γ value calculating means, which calculates a Δ development γ value, which is the difference between the target development γ value and the current development γ value; a step S4 in which, based on a change in the Δ development γ value data calculated by the Δ development γ value calculating means, the Δ development γ value and a threshold is compared by a toner deterioration estimating means, which estimates the degree of toner deterioration; and a step S5 in which, when the Δ development γ value exceeds the set threshold value, a toner deterioration alarm processing is performed.

Description

  The present invention relates to a toner deterioration prediction method, a toner deterioration prediction device, and an image forming apparatus.

  In an image forming apparatus such as a copying machine, a facsimile, a printer, a plotter, or a multi-function machine having a plurality of functions, a developing device that includes a toner and a carrier and uses a two-component developer in which these are mixed is widely known. Yes. In such a developing device, the toner supplied from the toner replenishing unit is conveyed while being mixed with the carrier by a screw, a paddle or the like, and is supplied to the developing roller. Thereafter, the toner is consumed by image formation, the toner is replenished from the toner replenishing portion, and the mixing, stirring, and conveyance with the carrier are repeated again.

  When image formation with a low image area ratio is continuously performed, the toner usage rate in the developer is low, so that the toner in the developer is not easily consumed, and the amount of toner that remains in the developing device for a long time increases. When the toner is not consumed for a long time and is continuously stirred in the developing device, the toner gradually deteriorates. When the toner is deteriorated, the frictional force of each toner particle is increased, and the flowability of the developer is deteriorated by gathering a large amount of such toner. Therefore, since the developer cannot move smoothly, the movement of the developer in the direction changing portion such as the developer moving path starts to be delayed, and the developer starts to accumulate in the direction changing portion. As described above, when the flowability of the developer deteriorates, the developer adheres unevenly to the developing roller, which causes a problem such as development failure. Therefore, it is necessary to perform maintenance before such a problem occurs by predicting the degree of toner deterioration. Patent Documents 1 to 3, which are known examples relating to a method for predicting the degree of toner deterioration, will be described below.

  The image forming apparatus described in Patent Literature 1 includes a sensor that detects the volume of the developer accommodated in the case, or a detection unit that detects pressure due to the developer in contact therewith. When the developer toner contained in the case deteriorates, the fluidity of the developer deteriorates, and therefore a portion where the developer stays in the case appears. Therefore, the bulk of the developer in the staying portion increases. By detecting such a change in bulk by the sensor, the degree of toner deterioration is determined. Further, paying attention to the fact that the pressure of the developer in the staying part pushing the inner wall of the case increases, there is a method for judging the degree of toner deterioration by detecting such a change in pressure by the detecting means. Proposed.

  In the image forming apparatus described in Patent Document 2, at least a photosensitive drum carrying a latent image on the surface and a developer carried on a developing sleeve provided on the photosensitive drum are supplied to the latent image on the photosensitive drum. In the image forming apparatus having the developing device that visualizes the image and the transfer device that transfers the toner image visualized on the photosensitive drum onto the recording medium, the unevenness of the toner image formed on the photosensitive drum The height of the toner image formed on the photosensitive drum is obtained by the detecting means, and if the height of the toner image is larger than the height reference value with respect to the toner adhesion amount, the toner is detected. A method for determining that the deterioration has occurred has been proposed.

  In the image forming apparatus described in Japanese Patent Application Laid-Open No. H10-228707, toner transfer is not established in the first region where the toner transfer to the conveyor belt is established, which is an area on the conveyor belt in contact with the photosensitive member. The respective toner amounts with the second region are acquired. Then, based on the difference in the toner amount, a method for determining that the toner has deteriorated if the difference in the toner amount is large, and determining that the toner has not deteriorated if the difference in the toner amount is small has been proposed. Yes.

However, the conventional toner deterioration prediction methods including the techniques described in Patent Documents 1 to 3 have a new configuration such as newly providing a sensor for detecting the bulk of the developer and a means for detecting the unevenness of the toner image. There was a problem of adding additional elements and extra costs associated with this.
The present invention has been made in view of the above circumstances, and it is possible to more accurately degrade toner without adding a new configuration and without extra cost by using a signal acquired in the past. The purpose is to predict the degree.

  In order to solve the above-mentioned problems and achieve the above-mentioned object, the invention according to claim 1 is a toner deterioration prediction method for predicting the degree of toner deterioration of a two-component developer for supplying a developer containing toner to a developing device. The development γ target value setting means for setting the development γ target value, which is an image quality index value, sets the development γ target value, and the development γ current value calculation means calculates the development γ current value. A step of calculating a current value; a step of calculating the Δ development γ by a Δ development γ calculating means for calculating a Δ development γ that is a difference between the development γ target value and the development γ current value; and the Δ development. and a step of predicting the degree of toner deterioration by means of toner deterioration prediction means for predicting the degree of toner deterioration based on a change in Δ development γ data calculated by the γ calculation means.

  According to the present invention, with the above-described configuration, the degree of toner deterioration is predicted using a signal acquired conventionally for controlling Δ development γ, so that no additional configuration is added and an extra cost is required. Therefore, the degree of toner deterioration can be predicted more accurately. This makes it possible to perform maintenance before a failure occurs due to toner deterioration.

1 is a schematic configuration diagram illustrating a copying machine as an image forming apparatus to which the present invention is applied. FIG. 2 is a partially enlarged view showing a part of a tandem image forming unit in FIG. 1. FIG. 3 is a diagram showing a transition of Δdevelopment γ obtained by conducting a test with an actual machine corresponding to FIGS. 1 and 2. FIG. 3 is a simplified control block diagram illustrating a control configuration of the first embodiment and the like. 6 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the first exemplary embodiment. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a first modification. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a second modification. It is the same machine number as the diagram of FIG. 3 was acquired, and is a diagram showing the transition of ΔVt during the same period. FIG. 6 is a diagram illustrating a relationship between a toner density and an output voltage of a toner density sensor. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the second exemplary embodiment. 14 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a third modification. 14 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a fourth modification. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the third exemplary embodiment. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a fifth modification. 14 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to a sixth modification. FIG. 14 is an F-number diagram showing a result of toner deterioration prediction based on changes in both signals of Δdevelopment γ and ΔVt in Modification 6.

  Hereinafter, embodiments of the present invention including examples will be described in detail with reference to the drawings. In each embodiment and the like, components (members and components) having the same function and shape are described once unless they are confused, and the description thereof is omitted by giving the same reference numerals.

(Embodiment 1)
FIG. 1 is a schematic configuration diagram showing a copying machine as an image forming apparatus to which the present invention is applied. As shown in FIG. 1, a copier 500 as an example of an image forming apparatus includes a printer unit 100, a paper feeding unit 200, a scanner unit 300, and a document conveying unit 400.
The printer unit 100 is disposed substantially at the center of the apparatus main body. The paper feeding unit 200 is disposed below the printer unit 100, and the scanner unit 300 serving as an image reading device is disposed above the printer unit 100. Further, on the scanner unit 300, a document transport unit 400 including an automatic document transport device (ADF) is disposed.

A tandem image forming unit 20 is disposed almost at the center of the printer unit 100. The tandem image forming unit 20 is configured by arranging process units 18Y, 18C, 18M, and 18Bk as image forming units of Y (yellow), C (cyan), M (magenta), and Bk (black) side by side. Yes. The process units 18Y, 18C, 18M, and 18Bk of the tandem image forming unit 20 are respectively drum-shaped photoconductors 40Y, 40C, and 40M that serve as image carriers on which Y, C, M, and Bk toner images are formed. 40Bk.
Since the process units 18Y, 18C, 18M, and 18Bk have the same configuration, the process units 18Y, 18C, 18M, and 18Bk and the photoconductors 40Y, 40C, 40M, and 40Bk are assigned subscript symbols representing toner colors. It will be attached.

  An exposure device 21 is provided above the tandem image forming unit 20. The exposure apparatus includes four laser diode (LD) light sources prepared for each color, a pair of polygon scanners composed of a six-surface polygon mirror and a polygon motor, and fθ arranged in the optical path of each light source. It is composed of a lens, a lens such as a long WTL, and a mirror. Laser light emitted from the LD in accordance with the image information of each color is deflected and scanned by a polygon scanner and irradiated to the photoreceptors 40Y, 40C, 40M, and 40Bk of each color.

  Below the tandem image forming unit 20, an endless belt-like intermediate transfer belt 10 is installed. In the illustrated example, the intermediate transfer belt 10 is configured to be wound around three support rollers 14, 15, and 16 and to be rotated and conveyed clockwise in the drawing. One of the three support rollers 14, 15, 16 is a drive roller connected to a drive motor (not shown) that rotationally drives the intermediate transfer belt 10, and the remaining two are driven rollers. is there. Further, between the first support roller 14 and the second support roller 15, a primary transfer roller 62 as a primary transfer unit sandwiches the intermediate transfer belt 10 between the photoreceptors 40 Y, 40 C, 40 M, and 40 Bk. It is provided so as to oppose. The primary transfer roller 62 has a function of transferring a toner image from the photoconductors 40Y, 40C, 40M, and 40Bk of the respective colors to the intermediate transfer belt 10. A primary transfer bias is applied to each primary transfer roller 62 by a power source (not shown). As a result, a primary transfer electric field for electrostatically moving the toner images on the photoreceptors 40Y, 40C, 40M, and 40Bk toward the intermediate transfer belt 10 is formed in the primary transfer nips for Y, C, M, and Bk. Is done.

  An intermediate transfer belt cleaning device 17 that removes residual toner remaining on the intermediate transfer belt 10 after image transfer is provided downstream of the third support roller 16. As a material of the intermediate transfer belt 10, a resin material such as polyvinylidene fluoride, polyimide, polycarbonate, polyethylene terephthalate or the like can be molded into a seamless belt and used. These materials can be used as they are, or the resistance can be adjusted with a conductive material such as carbon black. Further, using these resins as a base layer, a surface layer may be formed by a method such as spraying or dipping to form a laminated structure.

  A secondary transfer device 22 is disposed below the intermediate transfer belt 10. In the illustrated example, the secondary transfer device 22 is configured such that a secondary transfer belt 24 that is an endless belt is stretched between two rollers 23. Then, it is arranged so as to be pressed against the third support roller 16 via the intermediate transfer belt 10, and the image on the intermediate transfer belt 10 is transferred to a transfer material such as transfer paper as a sheet-like recording medium. As the secondary transfer belt 24, the same material as that of the intermediate transfer belt 10 can be used.

On the left side of the secondary transfer device 22, a fixing device 25 for fixing the image on the transfer material is disposed. The fixing device 25 is configured by pressing a pressure roller 27 against a fixing belt 26 that is an endless belt. The secondary transfer device 22 described above also has a sheet conveyance function for conveying the transfer material after image transfer to the fixing device 25. Of course, a transfer roller or a transfer charger may be disposed as the secondary transfer device, and in such a case, it is necessary to provide this transfer material conveying function separately.
In the illustrated example, the transfer material is reversely discharged below the secondary transfer device 22 and the fixing device 25 in parallel with the tandem image forming unit 20 or transferred to form images on both surfaces of the transfer material. A reversing device 28 for reversing and refeeding the material is provided. The printer unit 100 also includes a toner supply device (not shown).

The paper feeding unit 200 includes an automatic paper feeding unit disposed below the printer unit 100 (meaning that the paper feeding unit 200 is disposed and positioned), and a manual feed disposed on the side of the printer unit 100. Part. The automatic paper feed unit includes three paper feed cassettes 44 arranged in multiple stages in the paper bank 43, a paper feed roller 42 that feeds transfer material (transfer paper) from each paper feed cassette 44, and one piece of transfer material that has been fed out. A separation roller 45 and the like that are separated and sent to the paper feed path 46 are provided. Further, it also includes a transport roller 47 that transports the transfer material to the paper feed path 48 of the printer unit 100. On the other hand, the manual feed section has a manual feed tray 51, a separation roller 52 for separating and feeding the transfer material on the manual feed tray 51 one by one toward the manual feed path 53, and the like.
A pair of registration rollers 49 are disposed downstream of the paper feed path 48 of the printer unit 100. The registration roller 49 is formed between the intermediate transfer belt 10 serving as an intermediate transfer member and the secondary transfer device 22 at a predetermined timing after receiving a transfer material sent from the paper feed cassette 44 or the manual feed tray 51. To the secondary transfer nip.

When a copying operation is performed using the copying machine 500, a document is set on the document table 30 of the document transport unit 400. Alternatively, the document conveying unit 400 is opened, a document is set on the contact glass 32 of the scanner unit 300, and the document conveying unit 400 is closed to hold the document. When a start switch of an operation display unit (not shown) (see FIG. 4) in FIG. 1 is pressed, the following operation based on a command from a control unit (not shown) (see FIG. 4) provided in the copier 500 is automatically performed. To be done.
That is, when a document is set on the document transport unit 400, the document is transported and moved onto the contact glass 32, and then travels on the first traveling body 33 and the second traveling body 34. On the other hand, when the document is set on the contact glass 32, the scanner unit 300 is immediately driven to travel on the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34, and is reflected by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read. Thereafter, when the mode setting on the operation display unit or the automatic mode selection is set on the operation display unit, the image forming operation is started in the full color mode or the monochrome mode according to the reading result of the original.

  When the full color mode is selected, the photoconductors 40Y, 40C, 40M, and 40Bk rotate in the counterclockwise direction in FIG. The surfaces of the photoreceptors 40Y, 40C, 40M, and 40Bk are uniformly charged by a charging device 60 (see FIG. 2) as a charging unit. Each color photoconductor 40Y, 40C, 40M, and 40Bk is irradiated with laser light L (see FIG. 2) corresponding to the image of each color from the exposure device 21, and an electrostatic latent image corresponding to the image data of each color is formed. Each is formed. Each electrostatic latent image is developed by each color developing device 61 (see FIG. 2) by rotating the photoreceptors 40Y, 40C, 40M, and 40Bk, and each of the electrostatic latent images has a single color of yellow, cyan, magenta, and black. An image is formed. The toner images of the respective colors are sequentially superposed at the primary transfer nip for Y, C, M, and Bk where the photoreceptors 40Y, 40C, 40M, and 40Bk and the intermediate transfer belt 10 are in contact with the intermediate transfer belt 10 being conveyed. The toner image is electrostatically transferred to form a four-color superimposed toner image. As a result, a full color image is formed on the intermediate transfer belt. The photoconductors 40Y, 40C, 40M, and 40Bk after the transfer are subjected to photostatic discharge by a static eliminator 64 (see FIG. 2), and residual toner and the like are removed by a photoconductor cleaning device 63 (see FIG. 2).

  On the other hand, one of the plurality of paper feed rollers 42 provided in the paper feed unit 200 is selectively rotated to feed the transfer material from one of the paper cassettes 44 provided in multiple stages in the paper bank 43 of the paper feed unit 200. Then, the paper is separated one by one by the separation roller 45 and put into the paper feed path 46. Further, the sheet is conveyed by the conveying roller 47 and guided to the paper feed path 48 in the printer unit 100, and the leading end is abutted against the registration roller 49 and stopped. Alternatively, in the case of manual feeding, the sheet feeding roller 50 is rotated to feed the transfer material on the manual tray 51, separated one by one by the separation roller 52, and put into the manual feeding path 53. Stop against the registration roller 49. Then, the registration roller 49 is rotated in synchronization with the full-color image on the intermediate transfer belt 10, and the transfer material is fed into the secondary transfer nip formed between the intermediate transfer belt 10 and the secondary transfer device 22. Then, in the secondary transfer nip, the four-color superimposed toner image on the intermediate transfer belt 10 and the transfer material are in close contact with each other in synchronization. Then, the four-color superimposed toner image is secondarily transferred onto the transfer material by a transfer electric field or nip pressure formed in the secondary transfer nip, and becomes a full color image combined with the white color of the transfer material paper.

The transfer material on which the toner image has been transferred is conveyed by the secondary transfer device 22 and sent to the fixing device 25, and is fixed to the transfer material by applying heat and pressure by the fixing device 25. The sheet is guided to be switched and discharged by the discharge roller 56 and stacked on the discharge tray 57. Alternatively, the conveying direction is switched by the switching claw 55 and is put into the sheet reversing device 28, where it is reversed and fed again to the secondary transfer device 22. The paper is discharged onto the paper discharge tray 57. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.
After the predetermined number of images have been formed, post-image forming processing is performed, and then the rotation of the photoconductors 40Y, 40C, 40M, and 40Bk is stopped. In the post-image forming process, the photosensitive member is rotated one or more times with the charging bias and transfer bias turned off. At that time, the charge on the surface of the photosensitive member is discharged by the discharging means, and the photosensitive member is left uncharged and exposed to light. Prevent the body from deteriorating.

When the monochrome mode is selected, the support roller 15 moves downward to separate the intermediate transfer belt 10 from the photoreceptors 40Y, 40C, and 40M. Only the photoconductor 40Bk rotates counterclockwise in FIG. 1, the surface of the photoconductor 40Bk is uniformly charged by the charging device 60, a laser beam corresponding to the Bk image is irradiated, and a latent image is formed. The toner image is developed with Bk toner. This toner image is transferred onto the intermediate transfer belt 10. At this time, the three color photoconductors 40Y, 40C, and 40M other than Bk and the developing device 61 are stopped, and unnecessary consumption of the photoconductor and the developer is prevented.
On the other hand, the transfer material is fed from the paper feed cassette 44 and conveyed by the registration roller 49 at a timing that coincides with the toner image formed on the intermediate transfer belt 10. The transfer material onto which the toner image has been transferred is fixed by the fixing device 25 as in the case of a full-color image, and is processed through a paper discharge system corresponding to a designated mode. Thereafter, when the formation of two or more images is instructed, the above-described image forming process is repeated.

  As described above, the copying machine 500 is a tandem intermediate transfer type full-color copying machine. The process units 18Y, 18C, 18M, and 18Bk are detachable from the printer unit 100 as so-called process cartridges. In this case, the process units 18Y, 18C, 18M, and 18Bk are a common support that includes the photosensitive members 18Y, 18C, 18M, and 18Bk and at least one apparatus selected from several other apparatuses as one unit. It is something to support. Here, the other several devices mean the charging device 60, the developing device 61, and the photosensitive member cleaning device 63 shown in FIG.

  Taking the black process unit 18Bk as an example, a developing device 61 (see FIG. 2) as developing means for developing an electrostatic latent image formed on the surface of the photoreceptor 40Bk into a black toner image in addition to the photoreceptor 40Bk. )have. Further, it also has a photoconductor cleaning device 63 (see FIG. 2) that cleans transfer residual toner and the like adhering to the surface of the photoconductor 40Bk after passing through the primary transfer nip. In addition, a static elimination device 64 (see FIG. 2) that neutralizes the surface of the photoreceptor 40Bk after cleaning, a charging device 60 (see FIG. 2) that uniformly charges the surface of the photoreceptor 40Bk after static elimination, and the like are also included. The process units 18Y, 18C, and 18M for other colors have almost the same configuration except that the color of the handled toner is different.

  The developing device 61 may be configured as a developing device cartridge, and the developing device cartridge may be configured so as to be detachable and replaceable with respect to the printer unit 100 that is also the main body of the image forming apparatus.

With reference to FIG. 2, the detailed configuration of the process unit and its periphery will be described. FIG. 2 is a partially enlarged view showing a part of a tandem image forming unit 20 including four process units 18Y, 18C, 18M, and 18Bk. The four process units 18Y, 18C, 18M, and 18Bk have substantially the same configuration except that the colors of the toners to be used are different from each other. The subscripts C, M, and Bk are omitted.
As shown in the figure, the process unit 18 includes a charging device 60, a developing device 61, a primary transfer roller 62, a photoconductor cleaning device 63, a charge removal device 64, and the like around the photoconductor 40.

As the photosensitive member 40, a drum-shaped member is used in which a photosensitive organic layer is applied to a base tube made of aluminum or the like to form a photosensitive layer. Further, as the charging device 60, a non-contact charging type corona charger is used.
The photoreceptor 40 is not limited to the above-described one, and an endless belt may be used. The charging device 60 is not limited to that described above, and a contact charging type roller charger may be used.

The developing device 61 develops a latent image using a two-component developer containing a magnetic carrier and a nonmagnetic toner. An agitating unit 66 that conveys the two-component developer accommodated in the inside while agitating and supplies the developer to the developing sleeve 65, and development that transfers toner of the two-component developer attached to the developing sleeve 65 to the photoreceptor 40. Part 67. The developing sleeve is also called a developing roller.
The stirring unit 66 is provided at a position lower than the developing unit 67, and is provided on the bottom surface of the developing case 70, two screws 68 arranged in parallel to each other, a partition plate provided between the screws 68. Toner density sensor 71 and the like. The toner density sensor 71 is also called a T sensor.

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

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

  The photoreceptor cleaning device 63 has a cleaning blade 75 made of urethane rubber. The non-transferred toner adhering to the surface of the photoconductor 40 is mechanically scraped off by the mechanical action of the cleaning blade 75 to clean the surface of the photoconductor 40. The toner scraped off is scraped off in the axial direction by a toner conveying coil (not shown) provided at the bottom, and discharged to a waste toner bottle (not shown).

  Between the transfer roller 62 and the photoreceptor 40, a toner image detection sensor 69 is provided as an image density detection unit having a light emitting element and a light receiving element. The toner image detection sensor 69 is also called a P sensor and is a conventionally known sensor. A reference image (P pattern) for image density detection is formed on the photosensitive member by a developing potential which is a difference between a predetermined surface potential of the photosensitive member and a voltage (developing bias) applied to the developing device (developing device). In general, a toner density control system is used in which the density of the P pattern is detected by a P sensor, and toner supply from a toner supply device (not shown) to a developing device is controlled according to the detection result. ing. In this toner density control method, among the output values of the P sensor, the output value of the P sensor for the P pattern on the photoconductor 40 is Vsp, and the output value of the P sensor for the non-image area (background portion) on the photoconductor 40 is used. When Vsg is set, toner supply from the toner supply device to the developing device is controlled so that Vsp / Vsg becomes constant. In FIG. 2, the arrangement position of the toner image detection sensor 69 is intentionally shifted to the lower vicinity of the intermediate transfer belt 10 for the sake of simplicity.

  The toner concentration sensor 71 detects the toner concentration of the developer in the developing device. The toner density sensor 71 is also called a T sensor, and is a conventionally known sensor. As the toner concentration sensor 71, for example, a magnetic permeability sensor is used, and the toner concentration in the developer can be detected by detecting the magnetic permeability of the developer. However, other than the magnetic permeability sensor may be used as long as the toner concentration of the developer can be detected.

[Description of failure caused by toner deterioration]
When the toner is deteriorated, the frictional force of each toner particle is increased, and the flowability of the developer is deteriorated by gathering a large amount of such toner. Therefore, since the developer cannot move smoothly, the movement of the developer at the direction changing portion starts to be delayed, and the developer starts to accumulate at the direction changing portion. Thus, when the fluidity of the developer deteriorates, the developer adheres unevenly to the developing roller (development sleeve), and thus there is a problem that development failure occurs.
Further, when the toner deteriorates and the fluidity of the toner deteriorates, the toner is clogged while the toner is supplied from the toner supply unit. As a result, the toner is not replenished, and the toner density of the developer is reduced, resulting in a blurred image or an image failure due to carrier adhesion to the photoreceptor.

[Description of image index value development γ]
In general, the developing potential ΔV (the value obtained by subtracting the developing bias VB applied to the developing roller from the charging potential Vs of the photosensitive member as the image bearing member: ΔV = Vs−VB) and the toner adhesion amount on the photosensitive member with respect to the developing potential The ratio is substantially constant. This ratio is the development γ. When the development γ becomes a certain value or less, a blurred image is generated or carrier adhesion occurs on the photosensitive member, and the image quality is deteriorated. Therefore, in the conventional color image forming apparatus, the development γ is defined at a predetermined timing such as when the number of times of image formation reaches a predetermined number of times (for example, 200 times), when the power is turned on, or when returning from the power saving mode. Process control is performed to change various settings within the range. Hereinafter, the process control is referred to as “development γ adjustment control”.

In the development γ adjustment control, the reference latent image on the photoconductor is developed with a two-component developer to form a visible image for measurement, the toner adhesion amount is detected, and the development γ is calculated from the detected value. Then, various settings related to the development potential ΔV (the charging potential Vs of the photosensitive member, the development bias VB, etc.) are changed so that the calculated development γ becomes a value that is empirically ideal. Although development γ depends on the toner concentration of the two-component developer, it takes a relatively long time to adjust the toner concentration. Therefore, in conventional color image forming apparatuses, the toner concentration is adjusted during development γ adjustment control. Does not go. As a result, in the conventional color image forming apparatus, the time required for the development γ adjustment control is shortened, and the convenience for the user is enhanced.
The toner density of the two-component developer is adjusted by supplying toner so that the detection value of the toner density sensor 71 becomes a target value during image formation. With such development γ adjustment control, normally, the development γ is maintained within the specified range over time. However, when a mechanical abnormality such as an abnormal operation of the developing device, an abnormal toner replenishing operation, an abnormal latent image writing operation on the photosensitive member, or the like occurs, the development γ may be outside the specified range. In such a case, since maintenance such as repair is necessary, in the conventional color image forming apparatus, the abnormality of the development γ is notified and the maintenance is promoted.
When development γ becomes gradually uncontrollable, the difference between the target value of development γ (hereinafter referred to as “development γ target value”) and the current value of development γ (hereinafter referred to as “development γ current value”) (Δ Development γ = Development γ current value−Development γ target value) gradually increases.

FIG. 3 is a diagram showing the transition of Δ development γ in the actual machine No. 1 corresponding to FIGS. 1 and 2. In FIG. 3, the vertical axis represents Δ development γ, and the horizontal axis represents the number of prints (thousands). In addition, the vertical lines shown by broken lines in the figure indicate the timing at which a failure occurs, and the black triangle marks indicate the timing at which the developing device is replaced.
When the number of printed sheets is 400 × 1000 (kp) to 500 × 1000, the value of Δdevelopment γ is low, and a failure occurs as indicated by a broken line near 550 × 1000. If the threshold value of Δdevelopment γ for determining that a failure has occurred is −40, when the value of Δdevelopment γ becomes −40 or less, it is determined that the toner has deteriorated, and an alarm is issued to generate 550 kp It becomes possible to prevent failures that occur in the vicinity.
The threshold value “−40” for Δdevelopment γ is set as a threshold value for Δdevelopment γ in models including the actual machine No. 1, and is stored in advance in the ROM 1c of FIG. The alarm may be displayed as a warning to the user through, for example, an operation display unit (see FIG. 4) disposed in the copier of FIG. 1, or appropriate notification means (visual or auditory can be recognized by humans). Including all means).

  Further, a failure occurred when the number of printed sheets was around 1350 × 1,000 sheets, and then the development device was replaced (developer replacement), and the value of Δdevelopment γ decreased immediately after the development device was replaced. No failure has occurred since then. As described above, since the value of Δ development γ may become unstable immediately after replacement of the developing device, it is determined that the toner has deteriorated for a certain period (in this embodiment, 10 × 1,000 sheets) after replacement of the developing device. do not do. As a result, it is possible to avoid a false report when the value of Δdevelopment γ becomes unstable due to replacement of the developing device (developer).

  With reference to FIG. 4, the control configuration of the present embodiment will be described. FIG. 4 is a simplified control block diagram showing a control configuration including the first embodiment and the later-described embodiments. The copying machine 500 of this embodiment includes a control unit 1 as a control unit that controls the entire copying machine. The control unit 1 includes a CPU 1a having functions of a calculation unit and a control unit, and an information storage unit. The information storage unit includes a RAM including a nonvolatile RAM for storing data, a ROM, an HDD (Hard Disk Drive), and the like. In this embodiment, for example, a system OS, a copy, a facsimile, various control programs required for the printer process, a printer PDL (Page Description Language) processing system, a ROM 1c that stores initial setting values of the system, and a work memory It consists of RAM 1b and the like.

The CPU 1a, based on various signals from the various sensors 2 and signals set by various keys on the operation display unit 3, etc., via the information storage unit, the printer unit 100, the paper feeding unit 200, the scanner unit 300, and the document conveying unit 400. The drive unit and the liquid crystal display unit (not shown) of the operation display unit 3 are controlled. As various sensors 2, a toner image detection sensor 69 and a toner density sensor 71 are given as representative ones.
The CPU 1a according to the first embodiment functions as a development γ current value calculation unit that calculates the development γ current value, and a Δ development γ calculation unit that calculates Δ development γ that is a difference between the development γ target value and the development γ current value. Have Further, the CPU 1a has a function as a toner deterioration prediction unit that predicts the degree of toner deterioration based on the change in the Δ development γ data calculated by the Δ development γ calculation unit.

Information of various sensors such as development γ and Vt used in Embodiment 2 described later, or counter information such as the number of prints by internal management of the CPU 1a is periodically stored in the nonvolatile RAM 1b. The ROM 1c stores a toner density control program, an image density control parameter correction program, a toner deterioration prediction program shown in each flowchart to be described later, related data, and the like. The ROM 1c functions as a development γ target value setting unit or a development γ target value storage unit that sets a development γ target value that is an image quality index value. Further, as described with reference to FIG. 3, the ROM 1c stores in advance relational data that prevents the CPU 1a from determining that the toner has deteriorated for a certain period after the replacement of the developing device (10 × 1,000 sheets in this embodiment). It is remembered.
Note that the copier 500 is not limited to an example in which the toner deterioration prediction program is individually executed. For example, information is managed via a communication means such as a network or LAN on an image forming apparatus management apparatus generally called a controller that controls the image forming apparatus at a higher level, or on a dedicated monitoring server provided separately from the apparatus or controller. A computer system in a transmission / reception relationship may be used.

  Based on the test results of FIG. 3, the operation flow of the first embodiment will be described with reference to FIG. FIG. 5 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the first exemplary embodiment. In the flowchart of FIG. 5, the development γ target value setting means for setting the development γ target value, which is an image quality index value, sets the development γ target value in advance, and the development γ current value calculation means for calculating the development γ current value. A step of calculating the current value of development γ, a step of calculating Δ development γ by a Δ development γ calculating means for calculating Δ development γ which is a difference between the development γ target value and the current value of development γ, and Δ development γ A step of predicting the degree of toner deterioration (hereinafter also referred to as “toner deterioration prediction”) by a toner deterioration prediction means for predicting the degree of toner deterioration based on a change in Δ development γ data calculated by the calculation means. . Each of the steps substantially corresponds to each step of the flowchart (the same applies hereinafter). Including the flowchart described later, “Y” in the determination symbol represents “yes”, and “N” represents “no”.

First, in step S1, the development γ target value stored in the ROM 1c and the parameter relating to the current development γ stored in the RAM 1b as needed are read out. The parameters relating to the current development γ include the charging potential Vs of the photosensitive member 40, the developing bias VB applied to the developing sleeve 65, the toner adhesion amount on the photosensitive member 40, and the like. The development γ target value is determined in advance for each apparatus, and is set to, for example, 1.0 [mg / cm ² · kV]. The toner adhesion amount on the photoreceptor 40 is detected by a toner image detection sensor 69.
In step S2, the CPU 1a as the developing γ current value calculating unit calculates the developing γ current value. The current value of development γ is obtained from the relationship between the development potential and the toner adhesion amount when a reference image (P pattern) is formed on the photoreceptor 40. Taking the development potential on the horizontal axis and the toner adhesion amount on the vertical axis, a linear equation is obtained by the least square method, and the slope of this linear equation becomes the current value of development γ (for example, FIG. (See 8).

  Next, the process proceeds to step S3, where the CPU 1a as the Δ development γ calculation means calculates the current Δ development γ which is the difference between the development γ target value and the development γ current value. Next, the process proceeds to step S4, where the CPU 1a as the toner deterioration predicting means predicts the degree of toner deterioration based on the change in the Δ development γ data calculated in step S3 (step S4). Here, “based on the change in the calculated Δ development γ data” specifically means that the calculated data value of Δ development γ is a preset Δ development γ based on the test result of FIG. This means that it is performed by comparison / calculation of whether or not the threshold value “−40” is exceeded.

In step S4, when the calculated data value of Δdevelopment γ exceeds the threshold value “−40” of Δdevelopment γ, the process proceeds to step S5, where the toner deterioration alarm is a process for notifying that the toner has deteriorated. Processing is executed. As a specific example of the toner deterioration alarm process, for example, a message “Please replace the developer because of toner deterioration” is displayed on the liquid crystal display unit (not shown) of the operation display unit 3 in FIG. It is done by being made.
In addition to such an alarm display, the liquid crystal display unit may be displayed in a blinking manner, or when a buzzer is provided, a buzzer may be sounded. Furthermore, a method of issuing an alarm to the copier 500 as an image forming apparatus as an alarm via a LAN, or a method of issuing an alarm to a maintenance staff by e-mail or the like via the LAN may be used (the same applies hereinafter). .

  On the other hand, when the calculated data value of Δdevelopment γ does not exceed the threshold value “−40” of Δdevelopment γ in step S4, the process ends. The operation after step S1 in FIG. 5 is executed, for example, for each copy of the copying machine 500 or for every predetermined number of sheets (100 sheets, 1000 sheets, etc.), so the process returns to step S1, The operation described above may be repeated. The same applies to the flowcharts described below.

As described above, according to the first embodiment, the degree of toner deterioration is predicted using a signal acquired conventionally for controlling the Δ development γ. The degree of toner deterioration can be predicted more accurately without incurring costs. This makes it possible to perform maintenance before a failure occurs due to toner deterioration.
In addition, the change in the value of Δ development γ may increase during a certain period immediately after replacement of the developing device, but it does not occur due to toner deterioration. Can be prevented from being erroneously determined as deterioration.

(Modification 1 of Embodiment 1)
With reference to FIG. 6, the modification 1 (Claim 4 which cites Claim 1) of Embodiment 1 shown in FIGS. 1-5 is demonstrated. FIG. 6 is a flowchart illustrating an operation sequence related to toner deterioration prediction according to the first modification.
In the first modification, compared to the first embodiment, the CPU 1a as a toner deterioration prediction unit uses a weak stamp discriminator created by using a boosting method for calculating a preliminary prediction result of the toner deterioration degree. The main difference is in the provision.
An application example of a weighted majority classifier for predicting toner deterioration by performing a weighted majority rule using the prediction result calculated by the stamp weak classifier and the stamp weak classifier is disclosed in Patent Document 5, for example. Since it is known, only a brief description will be given.

In the first modification, the threshold value b and the weight α as reference values are generally created using a supervised learning algorithm called a boosting method. The boosting method is well known and described in, for example, Mathematical Sciences No. 489, MARCH 2004 “Information Geometry for Statistical Pattern Identification”.
First, a history from a normal state to a change to an abnormal state is prepared for a data set composed of a plurality of types of data (Δ development γ in the first modification). Then, for each of various data histories (Δ development γ in the present modification 1), the abnormal period is visually estimated from the shape of the temporal variation graph. The data corresponding to the abnormal period (Δ development γ in the first modification) is labeled with a negative polarity, while the other data (data in the normal period: Δ development γ in the first modification). A positive polarity label is attached to the. By repeating this operation 100 times, threshold values b1 to b100, discrimination polarities sgn1 to sgn100, and weighting values α1 to α100 are determined for various data (Δ development γ in the first modification), respectively.

  Next, it is determined whether each data is normal or abnormal based on temporal signals of various data (in the first modification, the number of prints). Since this determination is not a decisive factor for failure prediction (toner deterioration prediction), this determination is called weak determination processing. The weak discrimination processing is performed as in the following formulas 1 and 2. Ci represents a temporal signal.

  With reference to FIG. 6, the operation of the first modification will be described focusing on differences from the operation of the first embodiment illustrated in FIG. 5. The operation of the first modification starts from step S6 as shown in FIG. Compared with the operation of the first embodiment shown in FIG. 5, the operation of the first modification is that the weak discrimination process is performed in step S <b> 9, the toner deterioration prediction in step S <b> 10 is the weak discrimination result and the set threshold value. This is mainly different in that it is performed in the comparison. The operation of the modification 1 other than this difference is the same as that of the first embodiment.

  As described above, according to the first modification of the first embodiment shown in FIGS. 1 to 4, 6, and the like, in addition to the basic effects of the first embodiment, the CPU calculation can be performed at a very high speed. In addition, highly accurate diagnosis is possible.

(Modification 2 of Embodiment 1)
With reference to FIG. 7, the modification 2 (Claim 5 which cites Claim 1) of Embodiment 1 shown in FIGS. 1-4, FIG. 7 is demonstrated. FIG. 7 is a flowchart illustrating an operation sequence according to the toner deterioration prediction of the second modification.
In the second modified example, compared to the first modified example, the CPU 1a as the toner deterioration predicting unit performs a weighted majority decision using the prediction result calculated by the stamp weak discriminator to predict the toner deterioration. The main difference is that a calculation means is provided.

  In the second modification, after the weak discrimination process in the first modification is completed, an F value used for determination of abnormality prediction (toner deterioration prediction) is calculated based on the following formula 3.

The supervised data with the above-described threshold value, discrimination polarity and weighting value, and label are determined so that only data corresponding to an abnormal period is appropriately learned and has an F value with a negative polarity. Therefore, when the F value obtained by Equation 3 has a negative polarity, it can be estimated that an abnormal period has been entered.
If the F value becomes negative polarity as a process when an abnormal prediction result is obtained, an alarm is issued to the image forming apparatus as an alarm via the LAN as described above, or maintenance personnel are notified via the LAN. A method of issuing an alarm by e-mail or the like may be used. Further, a method for displaying a message prompting the replacement of the developer due to toner deterioration on the operation display unit of the apparatus may be used.
It is also possible to prepare a plurality of patterns for attaching labels to the data for the normal period and the abnormal period, and calculate the F value for each labeling. By labeling the normal period and the abnormal period using the level of toner deterioration during the toner deterioration period in the data as a threshold, and labeling a plurality of threshold levels of toner deterioration, a plurality of patterns can be labeled.

  With reference to FIG. 7, the operation of the second modification will be described focusing on differences from the operation of the first modification shown in FIG. 6. The operation of the modified example 2 starts from step S15 as shown in FIG. Compared with the operation of Modification 1 of FIG. 6, the operation of Modification 2 is that the F value is calculated by weighted discrimination in Step S19, and the F value calculated by the toner deterioration prediction in Step S20 is set. This is mainly different in that the comparison is made with the threshold value. The operation of the second modification other than this difference is the same as that of the first modification.

  As described above, according to the second modification of the first embodiment shown in FIGS. 1 to 4, 7, etc., in addition to the effects of the first modification, a faster and more accurate diagnosis can be performed.

(Embodiment 2)
In the second embodiment, as compared with the first embodiment, an output voltage Vt detected by a toner concentration sensor 71 as a conventionally known toner concentration detection unit shown in FIGS. 2 and 4 and a sign of a degree of toner deterioration to be described later. The main difference is that the degree of toner deterioration is predicted using ΔVt as an index. Hereinafter, the second embodiment will be described with a focus on differences from the first embodiment.
As shown in FIG. 2, a predetermined toner pattern is formed on an image carrier such as the photoreceptor 40 or the intermediate transfer belt 10, and the toner of the toner pattern is detected by a toner image detection sensor 69 which is an optical sensor (P sensor). The amount of adhesion is detected. Further, the toner density of the developer in the developing device 61 at that time is detected by a toner density sensor 71 also called a T sensor, and an image forming condition, a toner supply condition, and the like are determined based on these detection results. The output voltage detected by the toner density sensor 71 is Vt, and the reference voltage of the toner density sensor 71 is Vtref. ΔVt is obtained by taking the difference (Vt−Vtref) between Vt and Vtref.

The toner density sensor 71 detects the toner density, which is the ratio between the carrier and the toner in the developer, by detecting the magnetic permeability, can be sensed at any time regardless of the printing operation, and the detection interval is shortened. It is set. The detection timing is generally one that detects the toner density for each print.
FIG. 8 is a diagram showing the transition of ΔVt during the same period when the diagram of FIG. 3 is acquired. In FIG. 8, the vertical axis represents ΔVt (V), and the horizontal axis represents the number of prints (1,000 sheets: 1 kp). In addition, the vertical lines shown by broken lines in the figure indicate the timing when a failure occurs, and the black triangle marks indicate the timing when the developing device is replaced. When the number of prints is around 1300 kp, the value of ΔVt is large, and a failure occurs immediately after this. Assuming that the threshold value of ΔVt for determining the occurrence of a failure is 100, when the value of ΔVt becomes 100 or more, it is determined that the toner has deteriorated, and an alarm is issued, so that 1300 × 1,000 sheets (kp) It becomes possible to prevent failures that occur in the vicinity. The threshold value “100” of ΔVt is set as a threshold value of ΔVt in the model including the actual machine number 1, and is stored in advance in the ROM 1c of FIG.

In this case, since the alarm is issued just before the failure, it may not be possible to prevent the failure in advance. However, it is possible to know from the alarm that the failure is caused by toner deterioration. As a result, it is possible to reduce the time for investigating the cause in the time of maintenance work, shortening the maintenance work time, and by performing correct maintenance work, it occurs in the vicinity of 1350 × 1,000 sheets (kp) It becomes possible to prevent the failure that has occurred.
Further, a failure occurs when the number of printed sheets is around 1350 × 1000 (kp), and then the developing device (developer) is replaced. The value of ΔVt increases immediately after the developing device is replaced. Has not occurred. As described above, since the value of ΔVt may become unstable immediately after replacement of the developing device, it is not determined that the toner has deteriorated for a certain period of time (in this embodiment, 10 × 1,000 sheets) after replacement of the developing device. As a result, it is possible to avoid a false alarm when the value of ΔVt becomes unstable due to the replacement of the developing device (developer).

A control configuration of the second embodiment will be described with reference to FIG. The CPU 1a according to the second embodiment has a function as a ΔVt calculation unit that calculates ΔVt that is a difference between the output voltage Vt stored in the nonvolatile RAM 1b and the reference voltage Vtref of the toner density sensor 71. Further, it has a function as a toner deterioration prediction unit that predicts the degree of toner deterioration based on the change in the ΔVt data calculated by the ΔVt calculation unit.
The nonvolatile RAM 1b functions as a Vt holding unit that holds the output voltage Vt, and also stores ΔVt. Further, as described with reference to FIG. 8, the ROM 1 c stores in advance relational data that prevents the CPU 1 a from determining that the toner has deteriorated for a certain period after the replacement of the developing device (in this embodiment, 10 × 1,000 sheets). It is remembered.

  In FIG. 9, the horizontal axis represents the toner density (% by weight), the vertical axis represents the output voltage Vt (V) of the toner density sensor 71, and a line showing the relationship between the toner density and the output voltage of the toner density sensor 71. FIG. As shown in FIG. 9, the toner concentration sensor 71, which is a magnetic permeability sensor, can be linearly approximated within a certain toner concentration range. As can be seen from the figure, the higher the toner density, the smaller the Vt output value. Here, it is assumed that the output voltage of the toner density sensor 71 indicating the current toner density is Vt, and the reference voltage of the toner density sensor 71 for controlling the toner density is Vtref. The reference voltage Vtref of the toner concentration sensor is preset to a predetermined reference voltage by a toner concentration sensor provided for each apparatus. When the output voltage Vt is higher than the reference voltage Vtref, a toner replenishing operation is performed by driving a motor (not shown) of a toner replenishing unit (toner replenishing device) (not shown) in order to eliminate the difference ΔVt of Vtref−Vt. Conversely, when the output voltage Vt is lower than the reference voltage Vtref, the motor of the toner replenishing device is stopped and control is performed so that toner is not replenished. As the difference ΔVt of Vtref−Vt is larger, it is necessary to perform the toner replenishing operation, and it is understood that ΔVt can be a sign / index of toner deterioration.

Based on the test results of FIGS. 8 and 9, the operation flow of the second embodiment will be described with reference to FIG. FIG. 10 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the second exemplary embodiment. In the flowchart of FIG. 10, the output voltage Vt is held by a Vt holding unit that holds the output voltage Vt detected by the toner density sensor, and ΔVt that is the difference between the output voltage Vt and the reference voltage Vtref of the toner density sensor is calculated. A step of calculating ΔVt by the ΔVt calculating means, and a step of predicting the toner deterioration degree by the toner deterioration prediction means for predicting the toner deterioration degree based on a change in the ΔVt data calculated by the ΔVt calculation means. It is.
The operation of the second embodiment starts from step S25. In step S25, the toner density control reference value Vtref stored in the ROM 1c and the current output voltage value Vt transmitted from the toner density sensor 71 are read. Next, the process proceeds to step S26, where ΔVt (Vtref−Vt) is calculated by the CPU 1a as the ΔVt calculating means.

  Next, the process proceeds to step S27, where the CPU 1a as the toner deterioration predicting means predicts the degree of toner deterioration based on the change in ΔVt data calculated in step S26 (step S27). Here, “based on the change in the calculated ΔVt data” specifically means that the calculated data value of ΔVt has a threshold value “100” of ΔVt set in advance based on the test result of FIG. It means that it is performed by comparison / calculation of whether or not it exceeds.

  In step S27, when the calculated data value of ΔVt exceeds the threshold value “100” of ΔVt, the process proceeds to step S28, and a toner deterioration alarm process that is a process for notifying that the toner has deteriorated is executed. . On the other hand, if the calculated data value of ΔVt does not exceed the threshold value “100” of ΔVt in step S28, the process ends.

As described above, according to the second embodiment, the degree of toner deterioration is predicted using ΔVt. Therefore, the degree of toner deterioration can be predicted without adding a new configuration and without adding extra cost. it can. This makes it possible to perform maintenance before a failure occurs due to toner deterioration.
In addition, the change in the value of ΔVt may increase immediately after the developing device is replaced, but this is not a change caused by the deterioration of the toner. It is possible to prevent erroneous determination as deterioration.

(Modification 3 of Embodiment 2)
With reference to FIG. 11, a third modification (Claim 4 quoting Claim 2) of Embodiment 2 shown in FIGS. 1, 2, 4, and 8 to 10 will be described. FIG. 11 is a flowchart illustrating an operation sequence according to the toner deterioration prediction of the third modification.
In the third modification, compared to the second embodiment, the CPU 1a as the toner deterioration prediction unit uses a stamp weak discriminator created by using a boosting method for calculating a preliminary prediction result of the toner deterioration degree. The main difference is in the provision. The contents of the supervised learning algorithm by the stamp weak discriminator and the boosting method are the same as those of the first modification of the first embodiment.

  First, a history from a normal state to a change to an abnormal state is prepared for a data set composed of a plurality of types of data (ΔVt in Modification 3). Then, for each history of various data (ΔVt in this modification 3), the abnormal period is visually estimated from the shape of the temporal variation graph. The data corresponding to the abnormal period (ΔVt in the third modification) is labeled with a negative polarity, while the other data (data in the normal period: ΔVt in the third modification) has a positive polarity. Add a label. By repeating this operation 100 times, threshold values b1 to b100, discrimination polarities sgn1 to sgn100, and weighting values α1 to α100 are determined for various data (ΔVt in the third modification), respectively.

  Next, it is determined whether each data is normal or abnormal based on temporal signals of various data (the number of prints in the third modification). Since this determination is not a decisive factor for failure prediction (toner deterioration prediction), this determination is called weak determination processing. The weak discrimination processing is performed as in the above formulas 1 and 2. Ci represents a temporal signal.

  With reference to FIG. 11, the operation of Modification 3 will be described focusing on differences from the operation of Embodiment 2 shown in FIG. 10. The operation of the modified example 3 starts from step S30 as shown in FIG. Compared with the operation of the second embodiment shown in FIG. 10, the operation of the modification 3 is that the weak discrimination process is performed in step S32, the toner deterioration prediction in step S33 is the weak discrimination result and the set threshold value. This is mainly different in that it is performed in the comparison. The operations of the third modification other than this difference are the same as those in the second embodiment.

  As described above, according to the third modification of the second embodiment shown in FIGS. 1, 2, 4, 8 to 9, 11, etc., in addition to the basic effects of the second embodiment, the CPU computation Can be performed at a very high speed, and a highly accurate diagnosis is possible.

(Modification 4 of Embodiment 2)
With reference to FIG. 12, the modification 4 (Claim 5 which cites Claim 2) of Embodiment 2 shown in FIG.1, FIG.2, FIG.4, FIG. FIG. 12 is a flowchart illustrating an operation sequence related to toner deterioration prediction according to the fourth modification.
In the modified example 4, as compared with the modified example 3, the CPU 1a as the toner deterioration predicting means performs a weighted majority decision using the prediction result calculated by the weak stamp discriminator, and predicts the toner deterioration. The main difference is that a calculation means is provided.

  In the modified example 4, after the weak discrimination process in the modified example 3 is finished, an F value used for determination of abnormality prediction (toner deterioration prediction) is calculated based on the above mathematical formula 3. Since the F value calculation method and the like are the same as described above, the description thereof is omitted.

  With reference to FIG. 12, the operation of Modification 4 will be described focusing on the differences from the operation of Modification 3 shown in FIG. The operation of the modification 4 starts from step S35 as shown in FIG. Compared with the operation of Modification 3 of FIG. 11, the operation of Modification 4 is that the F value is calculated by weighted discrimination in step S38, and the F value calculated by the toner deterioration prediction in step S39 is set. This is mainly different in that the comparison is made with the threshold value. The operation of the modification 4 other than this difference is the same as that of the modification 3.

  As described above, according to the fourth modification of the second embodiment shown in FIGS. 1 to 4, 7, etc., in addition to the effects of the third modification, a faster and more accurate diagnosis is possible.

(Embodiment 3)
In the third embodiment, compared with the first and second embodiments, the degree of toner deterioration is predicted more accurately by using the toner deterioration predictive characteristic values of both Δ development γ of the first embodiment and ΔVt of the second embodiment. This is mainly different. Hereinafter, the third embodiment will be described with a focus on differences from the first and second embodiments.
In FIG. 8, for a failure occurring near 550 × 1,000 sheets (kp), no sign can be detected by ΔVt, but a sign can be detected by Δdevelopment γ shown in FIG. In the present embodiment, an example is shown in which a sign cannot be detected by ΔVt and a sign is detected by Δdevelopment γ. Conversely, a sign can not be detected by Δdevelopment γ, and a sign can be detected by ΔVt. Therefore, it is possible to predict toner deterioration more accurately by performing toner deterioration prediction based on changes in both signals of Δdevelopment γ and ΔVt, rather than detection only by Δdevelopment γ and detection only by ΔVt. can do.

Based on the test results of FIGS. 3 and 8, the operation flow of the third embodiment will be described with reference to FIG. 13. FIG. 13 is a flowchart illustrating an operation sequence according to toner deterioration prediction according to the third exemplary embodiment. The flowchart of FIG. 13 includes the steps shown in the flowcharts of FIGS. 5 and 10.
The operation of the third embodiment starts from step S45. In steps S45 to S47, operations similar to those in steps S1 to S3 in FIG. 5 are executed. Next, in steps S48 to S49, operations similar to those in steps S25 to S26 in FIG. 10 are performed. Next, in step S50, the CPU 1a as the toner deterioration predicting means predicts the toner deterioration degree based on the change in Δ development γ data and the change in ΔVt data calculated in step S47. Here, “based on the change in the calculated Δdevelopment γ data and the change in the calculated ΔVt data” means that the following two things are satisfied simultaneously. Specifically, this means that the data value of the calculated Δ development γ is performed by comparison / calculation as to whether or not the threshold value “−40” of the set Δ development γ is exceeded. At the same time, this means that the calculation is performed by comparison / calculation of whether or not the calculated data value of ΔVt exceeds the set threshold value “100” of ΔVt.

  In step S50, the calculated Δ development γ data value exceeds the set Δ development γ threshold “−40”, and the calculated ΔVt data value exceeds the ΔVt threshold “100”. Sometimes, the process proceeds to step S51. Then, a toner deterioration alarm process that is a process for notifying that the toner has deteriorated is executed. On the other hand, in step S50, the calculated Δdevelopment γ data value does not exceed the set Δdevelopment γ threshold “−40”, and the calculated ΔVt data value exceeds the ΔVt threshold “100”. If not, exit.

As described above, according to the third embodiment (Claim 3) shown in FIGS. 1 to 5, FIG. 8 to FIG. 10, and FIG. 13, by looking at changes in both Δ development γ and ΔVt data, The degree of toner deterioration can be predicted with high accuracy. This makes it possible to perform maintenance before a failure occurs due to toner deterioration.
In addition, during a certain period immediately after replacement of the developing device, fluctuations in the values of Δdevelopment γ and ΔVt may become large, but since this is not a variation that occurs due to toner deterioration, the certain period immediately after replacement of the developing device. By not determining as degradation, it is possible to prevent erroneous determination as degradation.

(Modification 5 of Embodiment 3)
With reference to FIG. 14, the modification 5 (Claim 4 which quoted Claim 3) of Embodiment 3 shown in FIGS. 1-5, 8-10, and 13 is demonstrated. FIG. 14 is a flowchart illustrating an operation sequence according to the toner deterioration prediction of the fifth modification.
In the modified example 5, as compared with the third embodiment, the CPU 1a as the toner deterioration predicting unit uses a weak stamp discriminator created by using a boosting method for calculating a preliminary prediction result of the toner deterioration degree. The main difference is in the provision. The contents of the supervised learning algorithm by the stamp weak discriminator and the boosting method are the same as those of the first modification of the first embodiment and the third modification of the second embodiment.

  First, for a data set composed of a plurality of types of data (Δ development γ and ΔVt in Modification 5), a history from a normal state to an abnormal state is prepared. Then, for each of various data histories (Δdevelopment γ and ΔVt in Modification 5), the abnormal period is visually estimated from the shape of the temporal variation graph. The data corresponding to the abnormal period (Δ development γ and ΔVt in the fifth modification) is labeled with a negative polarity, while other data (data in the normal period: data development in the fifth modification is Δ development). γ and ΔVt) are labeled with a positive polarity. By repeating this operation 100 times, threshold values b1 to b100, discrimination polarities sgn1 to sgn100, and weighting values α1 to α100 are determined for various data (Δdevelopment γ and ΔVt in Modification 5), respectively.

  Next, it is determined whether each data is normal or abnormal based on temporal signals of various data (the number of prints in the fifth modification). Since this determination is not a decisive factor for failure prediction (toner deterioration prediction), this determination is called weak determination processing. The weak discrimination processing is performed as in the above formulas 1 and 2. Ci represents a temporal signal.

  With reference to FIG. 14, the operation of the modified example 5 will be described focusing on differences from the operation of the third embodiment illustrated in FIG. 13. The operation of the modified example 5 starts from step S55 as shown in FIG. Compared with the operation of the third embodiment in FIG. 13, the operation of the modified example 5 is that the weak discrimination process is performed in step S <b> 60, the toner deterioration prediction in step S <b> 61 is the weak discrimination result and the set threshold value. This is mainly different in that it is performed in the comparison. The operation of the modification 5 other than this difference is the same as that of the third embodiment.

  As described above, according to the fifth modification of the third embodiment shown in FIGS. 1 to 5, 8 to 10, 14, etc., in addition to the basic effects of the third embodiment, the CPU operation is extremely fast. It is possible to make a diagnosis with high accuracy.

(Modification 6 of Embodiment 3)
With reference to FIG. 15, the modification 6 (Claim 5 which quoted Claim 3) of Embodiment 3 shown in FIGS. 1-5, 8-10, and 13 is demonstrated. FIG. 15 is a flowchart illustrating an operation sequence of the sixth modification of the third embodiment.
In the modified example 6, as compared with the modified example 5, the CPU 1a as the toner deterioration predicting means performs a weighted majority decision using the prediction result calculated by the weak stamp discriminator, and predicts the toner deterioration. The main difference is that a calculation means is provided.

  In the modified example 6, after the weak discrimination process in the modified example 5 is finished, an F value used for determination of abnormality prediction (toner deterioration prediction) is calculated based on the above formula 3. Since the F value calculation method and the like are the same as described above, the description thereof is omitted.

  With reference to FIG. 15, the operation of Modification 6 will be described focusing on differences from the operation of Modification 5 illustrated in FIG. 14. The operation of the modified example 6 starts from step S65 as shown in FIG. Compared with the operation of the modification 5 of FIG. 14, the operation of the modification 6 is that the F value is calculated by the weighted determination in step S <b> 71, and the F value calculated by the toner deterioration prediction in the step S <b> 72 is set. This is mainly different in that the comparison is made with the threshold value. The operation of the modification 6 other than this difference is the same as that of the modification 5.

In Modified Example 6, as a result of predicting toner deterioration based on changes in both signals of Δdevelopment γ and ΔVt, the F value is as shown in the diagram of FIG. In FIG. 16, the vertical axis represents the F value, and the horizontal axis represents the number of printed sheets (× 1,000 sheets).
A failure occurs when the number of printed sheets is around 1300 × 1000 and around 1400 × 1000, and the F value is 0 or less immediately before that. With respect to a failure near 600 × 1000 sheets, the F value was 0 or less near 400 to 500 × 1000 sheets before that, and it was verified that the failure could be predicted in advance.

  As described above, according to Modification 6 of Embodiment 3 shown in FIGS. 1 to 5, 8 to 10, 15, etc., in addition to the effects of Modification 5, faster and more accurate diagnosis can be performed. It becomes possible.

  Although the present invention has been described with respect to specific embodiments, the technical contents disclosed by the present invention are not limited to those exemplified in the above-described embodiments. That is, it may be configured by appropriately combining them, and it will be apparent to those skilled in the art that various embodiments, modifications, and examples can be configured within the scope of the present invention according to the necessity and application. It is.

Specifically, the toner deterioration prediction apparatus of the present invention is mainly configured by the control unit 1 in FIG.
The form in which the developer containing toner is replenished to the developing device is not limited to a toner replenishing unit that replenishes toner or a toner replenishing device, and for example, a developer called premix toner in which toner and carrier are mixed in advance. Including those that replenish.

1 control unit 1a CPU (an example of developing γ current value calculating means, Δ developing γ calculating means, ΔVt calculating means, toner deterioration predicting means)
1b Non-volatile RAM (an example of Vt holding means)
1c ROM (an example of developing γ target value setting means)
DESCRIPTION OF SYMBOLS 10 Intermediate transfer belt 18 Process unit 20 Tandem image formation part 21 Exposure apparatus 40 Photosensitive body (image carrier)
60 charging device 61 developing device 69 toner image detection sensor (image density detecting means)
71 toner density sensor 100 printer unit 200 sheet feeding unit 300 scanner unit 400 document conveying unit 500 copier (an example of an image forming apparatus)

JP 2008-076428 A JP 2010-217634 A JP 2012-203273 A JP 2011-174971 A Japanese Patent No. 5122254

Claims (9)

A toner deterioration prediction method for predicting the degree of toner deterioration of a two-component developer for supplying a developer containing toner to a developing device,
The development γ target value setting means for setting the development γ target value, which is an image quality index value, sets the development γ target value,
A step of calculating the development γ current value by a development γ current value calculating means for calculating a development γ current value;
Calculating Δ development γ by Δ development γ calculation means for calculating Δ development γ which is a difference between the development γ target value and the development γ current value;
Predicting the degree of toner deterioration by toner deterioration prediction means for predicting the degree of toner deterioration based on a change in Δ development γ data calculated by the Δ development γ calculation means;
A toner deterioration prediction method comprising: A toner deterioration prediction method for predicting the degree of toner deterioration of a two-component developer for supplying a developer containing toner to the developing device by using a toner concentration sensor for detecting a toner concentration in the developing device,
The output voltage Vt is held by Vt holding means for holding the output voltage Vt detected by the toner concentration sensor,
Calculating ΔVt by ΔVt calculating means for calculating ΔVt which is a difference between the output voltage Vt and a reference voltage Vtref of the toner density sensor;
Predicting the degree of toner deterioration by toner deterioration prediction means for predicting the degree of toner deterioration based on a change in ΔVt data calculated by the ΔVt calculation means;
A toner deterioration prediction method comprising: A toner deterioration prediction method for predicting the degree of toner deterioration of a two-component developer for supplying a developer containing toner to the developing device by using a toner concentration sensor for detecting a toner concentration in the developing device,
The development γ target value setting means for setting the development γ target value, which is an image quality index value, sets the development γ target value,
The output voltage Vt is held by Vt holding means for holding the output voltage Vt detected by the toner concentration sensor,
A step of calculating the development γ current value by a development γ current value calculating means for calculating a development γ current value;
Calculating Δ development γ by Δ development γ calculation means for calculating Δ development γ which is a difference between the development γ target value and the development γ current value;
Calculating ΔVt by ΔVt calculating means for calculating ΔVt which is the difference between the output voltage Vt held in the Vt holding means and the reference voltage Vtref of the toner density sensor;
Based on the change in the Δdevelopment γ data calculated by the Δdevelopment γ calculation unit and the change in the ΔVt data calculated by the ΔVt calculation unit, the toner deterioration prediction unit predicts the degree of toner deterioration. Predicting the degree,
A toner deterioration prediction method comprising: In the toner deterioration prediction method according to any one of claims 1 to 3,
The toner deterioration predicting means comprises a stamp weak discriminator created by using a boosting method for calculating a preliminary prediction result of the toner deterioration degree. The toner deterioration prediction method according to claim 4.
A toner deterioration prediction method comprising weighted majority calculation means for predicting the toner deterioration by performing a weighted majority using the prediction result calculated by the weak stamp discriminator. The toner deterioration prediction method according to any one of claims 1 to 5,
The developing device is configured to be detachable from the image forming apparatus main body,
A toner deterioration prediction method, wherein a toner deterioration is not determined for a certain period immediately after the development device replacement.   7. A toner deterioration prediction apparatus, wherein the toner deterioration prediction method according to claim 1 is carried out. An image forming unit,
An image forming apparatus, wherein the toner deterioration prediction method according to claim 1 is carried out. An image forming unit,
An image forming apparatus comprising the toner deterioration prediction device according to claim 7.

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