JP2019101238A - Image forming apparatus, image forming system, and method for diagnosing control electrode - Google Patents

Abstract

An object of the present invention is to provide a configuration that can more accurately diagnose the state of a grid electrode. [Solution] A toner amount detection sensor is a measurement point located at a position corresponding to a position where an airflow having a speed different by 10% or more from the average speed in the width direction flows in the speed distribution of the airflow passing through the shield member of the charger. They are located at A, B, and C. In the diagnostic mode, the printer control section forms a diagnostic toner image using the potential difference between the development potential and the charging potential without performing exposure using the exposure device. Then, the diagnostic toner images are detected at measurement points A, B, and C, and information regarding the state of the grid electrode is output based on the detected results. [Selection diagram] Figure 7

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multifunction machine having a plurality of functions of these, an image forming system provided with such an image forming apparatus, and a control electrode provided in such an image forming apparatus. Related to the diagnosis method of

  As an image forming apparatus such as an electrophotographic system, a configuration is known in which the surface of a photosensitive drum as an image carrier is charged by a corona charger as a charging unit. There is also known a scorotron type configuration provided with a discharge electrode and a control electrode (grid electrode) as a corona charger.

  In this corona charger, since the foreign matter adheres to the control electrode by use and the charging potential changes, the control electrode may be periodically replaced. As a configuration for notifying such a replacement time of the control electrode, a current flowing from the discharge electrode to a shield case (casing) accommodating the discharge electrode is detected, and the detected replacement current time is predicted from the detected current value. A configuration is proposed (Patent Document 1).

  However, in the case of the configuration described in Patent Document 1, not the control electrode, for example, the shield case may be contaminated, and the current value flowing in the shield case may change, and the state of the control electrode may not be accurately grasped. For this reason, in the case of the configuration described in Patent Document 1, there are cases where the replacement time of the control electrode can not be accurately predicted.

  On the other hand, in corona chargers with control electrodes, the airflow configuration is often arranged to pass between the control electrodes. Here, conventionally, foreign matter may adhere to the inside of the corona charger due to the air flow, and the charging potential may change. In addition, it is known that the control electrode factor is large and the factor of the discharge electrode and the shield plate is small for the influence on the change of the charging potential due to the adhesion of the foreign matter due to the air flow.

  Therefore, it is conceivable to develop the test toner on the photosensitive drum and estimate the amount of toner on the photosensitive drum and the intermediate transfer member by an optical detection member such as a patch detection sensor to estimate the contamination of the control electrode.

JP 2002-132025 A

  However, with the above method, it is not possible to distinguish whether the toner amount has changed due to other factors such as developing means, or the toner amount has changed due to the adhesion of foreign matter to the control electrode.

  It is known that the control electrode has a foreign matter adhesion distribution corresponding to the air flow distribution. Therefore, detection is performed at a position corresponding to a position where the wind speed is high (the foreign object is easily attached) in the airflow distribution in the longitudinal direction and a position corresponding to a low speed (the foreign object is not easily attached). As a result of detection at a plurality of longitudinal points, if there is a change in the toner amount corresponding to the wind speed, the possibility of foreign matter adhesion on the control electrode is high. On the other hand, when there is no change in the toner amount according to the wind speed, it can be judged that the possibility of other causes is high.

  An object of the present invention is to provide a configuration that can diagnose the state of the control electrode more accurately.

  According to the present invention, a rotating image carrier, a case having an opening on the side facing the image carrier, a discharge electrode disposed in the case and discharging when a voltage is applied, and the case of the case A charging unit disposed on the side of the image carrier relative to the discharge electrode, to which a voltage is applied, and charging means for charging the surface of the image carrier, and airflow forming means for forming an air flow passing through the inside of the housing An exposure unit for exposing the surface of the image carrier charged by the charging unit to form an electrostatic latent image; and developing the electrostatic latent image formed on the surface of the image carrier with a developer A velocity distribution of the air flow passing through the inside of the housing, the air flow at a speed different by 10% or more from the average speed in the width direction intersecting the rotation direction of the image carrier; Developer image developed by the developing means The surface of the image carrier is charged to a predetermined charging potential by developer amount detecting means capable of detecting the developer amount, storage means storing the detection result of the developer amount detecting means, and the charging means A diagnostic developer image is formed on the image carrier by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential without exposure by the exposing unit, and the developer amount detecting unit An image forming apparatus, comprising: execution means capable of executing a diagnosis mode for detecting a diagnostic developer image and outputting information related to the state of the control electrode based on the detected result.

  Further, according to the present invention, a rotating image carrier, a case having an opening on the side facing the image carrier, a discharge electrode disposed in the case and discharging when a voltage is applied, and the case And a control electrode disposed closer to the image carrier than the discharge electrode, to which a voltage is applied, and charging the surface of the image carrier, and the image carrier charged by the charging device. Means for exposing the surface of the image carrier to form an electrostatic latent image, developing means for developing the electrostatic latent image formed on the surface of the image carrier with a developer, and a developer developed by the developing means Transfer means for transferring an image to a recording material, fixing means for fixing a developer image on a recording material to which a developer image has been transferred by the transfer means, and a charging potential of the surface of the image carrier by the charging means To perform exposure by the exposure unit. Instead, the diagnostic developer image formed on the image carrier by the potential difference between the developing potential applied to the developing means and the predetermined charging potential is transferred onto the recording material by the transfer means, and transferred. When a developer image is fixed on a recording material by the fixing unit and output, a diagnostic mode can be executed that displays that the diagnostic developer image does not indicate an abnormality of the apparatus on the output recording material And an image forming apparatus characterized by comprising:

  Further, the present invention is an image forming system including an image forming apparatus and a diagnosis unit, wherein the image forming apparatus includes a rotating image carrier, and a case opened at a side facing the image carrier. A discharge electrode disposed in the housing and discharging when a voltage is applied, and a control electrode disposed closer to the image carrier than the discharge electrode of the housing and to which a voltage is applied; An electrostatic latent image is formed by exposing the surface of the image carrier charged by the charging means, charging means for charging the surface of the image carrier, air flow forming means for forming an air flow passing through the inside of the housing, and Exposure means, a developing means for developing an electrostatic latent image formed on the surface of the image carrier with a developer, and a velocity distribution of an air flow passing through the inside of the housing, the direction of rotation of the image carrier crosses the rotation direction. 10% or more different from the average speed in the width direction A developer amount detecting unit is disposed at a position corresponding to a position where an air flow at a high speed flows, and the developer amount of the developer image developed by the developing unit can be detected; The diagnostic developer is formed on the image carrier by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential while being charged to a predetermined charging potential without exposure by the exposing unit. An execution unit capable of executing a diagnosis mode for causing the developer amount detection unit to detect the diagnostic developer image; and a transmission unit for transmitting information detected in the diagnosis mode, the diagnosis unit comprising: An image forming system is characterized in that the information transmitted from the transmitting means is received, and the replacement time of the control electrode is diagnosed based on the information.

  Further, according to the present invention, a rotating image carrier, a case having an opening on the side facing the image carrier, a discharge electrode disposed in the case and discharging when a voltage is applied, and the case And a control electrode which is disposed closer to the image carrier than the discharge electrode and to which a voltage is applied, and includes an electrifying means for charging the surface of the image carrier, and an air flow forming an air flow passing through the inside of the housing. Means, exposure means for exposing the surface of the image carrier charged by the charging means to form an electrostatic latent image, and developing the electrostatic latent image formed on the surface of the image carrier with a developer Of the developing means and the velocity distribution of the air flow passing through the inside of the housing, the position of the air corresponding to the position at which the air velocity different by 10% or more with respect to the average velocity in the width direction Current developed by the developing means. A developer amount detection unit capable of detecting a developer amount of a developer image, and a diagnosis method of a control electrode for diagnosing a replacement time of the control electrode of an image forming apparatus, comprising: the image carrier by the charging unit The developer developer image on the image carrier by the potential difference between the developing potential applied to the developing means and the predetermined charging potential without charging the surface of the toner to a predetermined charging potential and performing exposure by the exposure means. A first step of detecting the diagnostic developer image by the developer amount detecting means, and a second step of diagnosing a replacement time of the control electrode based on a result detected by the first step; In a diagnostic method of a control electrode characterized in that

  According to the present invention, the state of the control electrode can be diagnosed more accurately.

FIG. 1 is a schematic sectional view of an image forming apparatus according to a first embodiment. FIG. 2 is a control block diagram of the image forming apparatus according to the first embodiment. FIG. 2 is a schematic configuration diagram of a charger according to the first embodiment and an image forming unit for describing an air flow around the charger. 6 is a graph showing the relationship between the measurement position in the width direction of the toner amount detection sensor and the wind velocity distribution in the longitudinal direction. The graph which shows the relationship between the wind speed and the toner density on paper. 6 is a graph showing the relationship between the number of image formations under two conditions and the density difference detected by the toner amount detection sensor. 6 is a flowchart of a diagnosis mode according to the first embodiment. FIG. 7 is a view showing an example of display of grid replacement timing according to the first embodiment. FIG. 7 is a block diagram showing an image forming system according to a second embodiment. The figure which shows an example of the display which selects the decision | availability of execution of the diagnostic mode which concerns on 3rd Embodiment. FIG. 16 is a view showing an example of an image on paper output in a diagnosis mode according to the fourth embodiment.

First Embodiment
The first embodiment will be described using FIGS. 1 to 8. First, a schematic configuration of the image forming apparatus according to the present embodiment will be described with reference to FIG.

[Image forming apparatus]
An image forming apparatus 600 according to the present embodiment is an electrophotographic color printer in which a plurality of image forming units are arranged in parallel and an intermediate transfer system is adopted. Such an image forming apparatus 600 includes an image reading unit 1R and an image output unit 1P. The image reading unit 1R optically reads an original image, converts it into an electric signal, and transmits the electric signal to the image output unit 1P. The image output unit 1P includes a plurality of, in the present embodiment, four image forming units 10a, 10b, 10c, and 10d juxtaposed, a feeding unit 20, an intermediate transfer unit 30, a fixing unit 40, and cleaning. And a unit 50.

  Each unit of the image output unit 1P will be described. Since the image forming units 10a, 10b, 10c, and 10d have the same configuration, the image forming unit 10a will be representatively described, and for the other image forming units, subscripts of reference numerals indicating the same configuration will be used to form the image. It changes to the subscript corresponding to a part and omits explanation. The image forming units 10a, 10b, 10c, and 10d form toner images (developer images) of black, cyan, magenta, and yellow, respectively.

  In the image forming unit 10a, a drum-shaped electrophotographic photosensitive member as an image bearing member, that is, the photosensitive drum 11a is rotatably supported and rotationally driven in the arrow direction. Around the photosensitive drum 11a, a charger 12a as a charging unit, a developing unit 14a as a developing unit, and a cleaning unit 15a are sequentially disposed in the rotational direction. Further, an exposure device 13a as an exposure means and a folding mirror 16a are disposed above the photosensitive drum 11a in FIG. 1, and an intermediate transfer unit 30 is disposed below the FIG.

  The charger 12a applies a uniform charge amount to the surface of the photosensitive drum 11a to charge the surface. In the present embodiment, a corona charger is used as the charger 12a. Details will be described later. The exposure device 13a applies a laser beam modulated according to an image signal from the image reading unit 1R and an image signal sent from an external terminal such as a personal computer onto the photosensitive drum 11a charged via the folding mirror 16a. It exposes and forms an electrostatic latent image. The primary charger uses a corona charger and will be described in detail later.

  The developing device 14a contains a black developer (toner), and develops (develops) the electrostatic latent image formed on the surface of the photosensitive drum 14 with the toner, thereby forming a black toner image (developer image Form). The developing devices 14b, 14c, and 14d contain toners of magenta, cyan, and yellow, respectively, and similarly to the developing device 14a, form toner images of the respective colors on the photosensitive drums 11b, 11c, and 11d. .

  The developing device 14a will be specifically described with reference to FIG. 3 described later. The developing device 14 a includes a developing container 141 and a developing sleeve 142 as a developer carrier. The developing container 141 contains a two-component developer including nonmagnetic toner and a magnetic carrier. The developing sleeve 142 carries the developer in the developing container 141 and conveys the developer to a developing area facing the photosensitive drum 11a. When a predetermined developing bias (developing potential) is applied to the developing sleeve 142, the toner carried on the developing sleeve 142 flies and the electrostatic latent image formed on the photosensitive drum 11a is developed by the toner. Be done. The developer may be a one-component developer containing no carrier other than the two-component developer described above.

  The toner images of the respective colors formed on the photosensitive drums 11a, 11b, 11c and 11d are transferred onto the intermediate transfer belt 31 as an intermediate transfer member constituting the intermediate transfer unit 30 at the primary transfer portions Ta, Tb, Tc and Td. It is superimposed and transferred. Thus, a full-color toner image is formed on the intermediate transfer belt 31.

  The intermediate transfer unit 30 as transfer means includes an intermediate transfer belt 31, primary transfer devices 33a, 33b, 33c, 33d, an inner secondary transfer roller 34, an outer secondary transfer roller 35, and the like. Then, the intermediate transfer unit 30 transfers the toner images formed on the photosensitive drums 11a, 11b, 11c, and 11d to the recording material via the intermediate transfer belt 31.

  The intermediate transfer belt 31 is an endless belt, stretched over a plurality of stretching rollers, and rotationally driven in the arrow direction by a drive roller 32 among the plurality of stretching rollers. Primary transfer devices 33a, 33b, 33c and 33d as primary transfer means are arranged at positions of primary transfer portions Ta, Tb, Tc and Td on the inner peripheral surface of the intermediate transfer belt 31. Further, among the plurality of stretching rollers, the secondary transfer inner roller 34 and the secondary transfer outer roller 35 which holds the intermediate transfer belt 31 between the secondary transfer inner roller 34, the intermediate transfer belt 31 is placed on the intermediate transfer belt 31. A secondary transfer portion Te for transferring a toner image to a recording material is formed.

  On the downstream side of the primary transfer portion Ta with respect to the rotational direction of the photosensitive drum 11a, the cleaning device 15a cleans the drum surface by scraping off the toner not transferred to the intermediate transfer belt 31 and left on the photosensitive drum 11a. According to the process described above, image formation with each toner is sequentially performed.

  The feeding unit 20 includes cassettes 21a and 21b and a manual feed tray 27 for storing the recording material P, and pickup rollers 22a, 22b and 26 for feeding the recording material P one by one from the cassettes 21a and 21b or the manual feed tray 27. And. Examples of the recording material include sheet materials such as paper, plastic film and cloth.

  The feeding unit 20 further includes a conveying roller pair 23 for conveying the recording material P fed from the pickup rollers 22a, 22b, 26 further, a conveying guide 24, and registration rollers 25a, 25b. The registration rollers 25a and 25b send the recording material P to the secondary transfer unit Te in accordance with the image formation timing of each of the image forming units 10a to 10d. Then, the toner image on the intermediate transfer belt 31 is transferred onto the recording material P at the secondary transfer portion Te.

  The cleaning unit 50 cleans the belt surface by scraping off the toner left on the intermediate transfer belt 31 without being transferred to the recording material P. The amount of developer on the outer peripheral surface of the intermediate transfer belt 31 is such that it faces the intermediate transfer belt 31 on the downstream side of the rotation direction of the intermediate transfer belt 31 of the primary transfer portion Ta and on the upstream side of the secondary transfer portion Te. A toner amount detection sensor 60 as a detection means is provided.

  The toner amount detection sensor 60 can detect the toner amount (developer amount) of the toner image on the intermediate transfer belt 31. Specifically, the toner amount detection sensor 60 has a light emitting element for emitting light and a light receiving element for receiving light. Then, the light emitted from the light emitting element is made incident on the surface of the intermediate transfer belt 31, and the amount of reflection is detected by the light receiving element. The amount of reflection is correlated with the amount (density) of the toner image of the toner image on the intermediate transfer belt 31, so the toner amount detection sensor 60 can detect the amount of toner on the intermediate transfer belt 31.

  The fixing unit 40 as a fixing unit includes a fixing roller having a heat source, and a pressure roller forming a fixing nip portion between the fixing roller and the fixing roller. The recording material P on which the toner image is transferred at the secondary transfer portion Te is conveyed to the fixing nip portion of the fixing unit 40, and is heated and pressed, whereby the toner image is fixed on the recording material P. The recording material P on which the toner image is fixed is discharged to a discharge tray 51 outside the apparatus.

[Control unit]
Next, the configuration regarding control of the image output unit 1P of the image forming apparatus 600 of the present embodiment will be described using FIG. Image information is input to the image control unit 100 in the image forming apparatus 600 from the image reading unit 1R or the like. The information input to the image control unit 100 is sent to the printer control unit 101, and the printer control unit 101 executes control to cause an operation according to the image information.

  The printer control unit 101 as an execution unit is provided with a CPU (Central Processing Unit) 101 a and a memory 101 b. A ROM (Read Only Memory) 101c is provided in the memory 101b as a storage unit. The ROM 101 c stores a program corresponding to the control procedure. The CPU 101a controls each unit while reading a program stored in the ROM 101c. Further, in the memory 101b, a RAM (Random Access Memory) 101d in which work data and input data are stored is also provided. The CPU 101a performs control by referring to data stored in the RAM 101d based on the above-described program and the like.

  A sensor unit 103, a high voltage power supply unit 104, a drive unit 105, an LP unit 106, a fan unit 107, and the like are connected to such a printer control unit 101. In addition, the printer control unit 101 is provided with an interface 102 for exchanging external information with a data center or the like to be described later via the Internet or the like. Further, an operation display unit 108 as a display unit is connected to the printer control unit 101.

  The sensor unit 103 includes various sensors such as the above-described toner amount detection sensor 60 (FIG. 1) and an environment sensor (not shown) capable of detecting the temperature and humidity at which the image forming apparatus is used. The high voltage power supply unit 104 includes various power supplies for applying a voltage to a developing device, a charger, a primary transfer device, a secondary transfer outer roller, and the like. The driving unit 105 includes various driving sources such as a photosensitive drum, a developing device, a motor for driving a driving roller, and the like.

  The LP unit 106 controls a laser for forming an exposure portion potential on the photosensitive drum by the exposure device. The fan unit 107 controls various fans that form an air flow near the charging device and around the fixing device. Among various fans, an exhaust fan for exhausting air in the apparatus is connected with a filter for suppressing discharge of VOC (volatile organic compound), toner, etc. out of the image forming apparatus. .

  The operation display unit 108 is a user interface provided in the image forming apparatus 600, for example, having a liquid crystal panel and operation buttons. The user can perform various settings of the image forming apparatus 600 from the operation display unit 108. In addition, the operation display unit 108 can display information on various states of the image forming apparatus 600, in particular, the state of grid electrodes described later, for example, information on the replacement time.

  Furthermore, the image forming apparatus 600 has a replenishment mechanism (not shown) that replenishes toner when the amount of toner in the developing device decreases. The printer control unit 101 integrates the replenishment amount of toner since the start of use of the developing device, and stores the integrated amount in the memory 101 b. The image output unit 1P is a portion having the above-described image forming units 10a to 10d, the fixing unit 40, and the like. The image output unit 1P detects a sensor and high voltage according to a control signal from the printer control unit 101. The application and drive OFF / ON are controlled.

[Air flow around charger and charger]
Next, the air flow around the charging device 12a and the charging device 12a will be described with reference to FIG. As described above, the charger 12a of the present embodiment is a corona charger. Therefore, the charger 12a includes a shield member 12s, a wire member 12w, and a grid electrode 12g.

  The shield member 12s as a housing is open at the side facing the photosensitive drum 11a, and surrounds the wire member 12w and the grid electrode 12g. That is, the shield member 12s has a width direction (rotation of the photosensitive drum 11) intersecting with both sides of the wire member 12w and the grid electrode 12g in the rotational direction of the photosensitive drum 11a and the rotation direction of the photosensitive drum 11a (arrow direction in FIG. 3). It is arranged on both sides of the direction parallel to the axial direction. In the present embodiment, the shield member 12s is held with a width of about 30 mm in the rotational direction of the photosensitive drum 11a, and the wire member 12w is disposed in the central portion in the width direction.

  The wire member 12 w as a discharge electrode is disposed in the shield member 12 s (in the housing), and is discharged when a voltage is applied. In the present embodiment, the wire member 12 w is a conductive wire containing tungsten with a diameter of 50 μm.

  The grid electrode 12g as a control electrode is disposed closer to the photosensitive drum 11a (image carrier side) than the wire member 12w of the shield member 12s, and a voltage is applied. In the present embodiment, the grid electrode 12g is disposed at a position 9.0 mm away from the wire member 12w in the drum direction and at a position 1.2 mm away from the surface of the photosensitive drum 11a.

  The grid electrode 12g has a role of stably focusing the potential on the photosensitive drum 11a, and the region of the grid electrode 12g for focusing the photosensitive drum potential has a width of 340 mm in the longitudinal direction (width direction). Such a grid electrode 12g is formed of a conductive material containing iron. Specifically, for the grid electrode 12g, a plate-like stainless steel (SUS) was used which was etched to a specific mesh shape only in the image forming area. The image forming area is an area on the photosensitive drum 11a where an electrostatic latent image can be formed.

  At the time of charging, a voltage is applied so that a current of 800 μA flows in the wire member 12w, and a voltage of -600 V is applied to the grid electrode. By supplying a current to the wire member 12w, corona discharge is started around the wire member 12w, and the photosensitive drum 11a is charged by the ion flow generated by the corona discharge. In the present embodiment, the surface of the photosensitive drum 11a is charged to about -500V.

  In the present embodiment, the potential sensor 70 is disposed on the downstream side of the exposure position of the exposure device 13a and on the upstream side of the developing device 14a in the rotational direction of the photosensitive drum 11a. The potential sensor 70 is a sensor that measures the surface potential of the photosensitive drum 11a. The printer control unit 101 (FIG. 2) uses the potential sensor 70 to adjust the voltage applied to the grid electrode 12g so that the charged potential of the photosensitive drum 11a becomes -500V. Further, the potential sensor 70 is disposed at the center (image center) of the image forming area in the width direction.

  Moreover, in this embodiment, it has the air flow formation part 210 as an air flow formation means which forms the air flow which passes through the inside of 12 d of shield members. The air flow forming unit 210 includes an air supply fan 200, an air supply duct 203, an exhaust fan 201, and an exhaust duct 204. In the present embodiment, the air flow forming unit 210 further includes an air supply filter 206, a toner filter 205, and an ozone filter 202.

  The air flow forming unit 210 prevents an ion flow from staying in the charger 12 a due to an air flow (air flow) formed by the air supply fan 200, the exhaust fan 201, the air supply duct 203, the exhaust duct 204 and the like during charging. There is. The flow of the air flow is indicated by arrows A1 and A2 in FIG.

  The air supplied to the charger 12a is indicated by an arrow A1. As for the air supply air A1, the air that has passed through the air supply filter 206 for removing dust by the air supply fan 200 passes through the air supply duct 203, and the inside of the charger 12a from above the charger 12a (that is, a shield member 12s)). The air supplied into the charger 12a passes through the inside of the charger 12a and flows downstream in the rotational direction of the photosensitive drum 11a.

  Exhaust air which passes through the inside of the charger 12a and is exhausted is indicated by an arrow A2. The exhaust air A2 passes through the exposure portion exposed by the laser L formed by the exposure device 13a. Then, the exhaust air A2 is guided by the exhaust fan 201 to the exhaust duct 204 on the front side (upstream in the rotational direction) of the developing device 14a and passes through the toner filter 205 to remove toner and dust. pass. Then, it passes through the ozone filter 202 and is exhausted out of the image forming apparatus.

  Here, when the air flow passing through the inside of the charger 12a is weak, ozone substances generated at the time of discharge stay in the charger. It is known that the image flow occurs when the ozone substance adheres to the surface of the photosensitive drum 11a. For this reason, it is preferable to move the charger 12a away from the vicinity of the photosensitive drum 11a. Further, the toner scattered from the developing device 14a or the like flows into the charger 12a, and the scattered toner adheres to parts in the charger 12a, which causes a problem of lowering the charging performance. Therefore, it is preferable to set the air flow passing through the charger 12a to a certain strength or more.

[Speed distribution of air flow in charger in the longitudinal direction]
Next, the velocity distribution (wind velocity distribution) in the width direction (longitudinal direction) of the air flow in the shield member 12s of the charger 12a will be described. As for the air flow supplied to the charger 12a, the shape and characteristics of the air supply fan 200 with respect to the longitudinal length of the charger 12a, and that the air supply duct 203 from the air supply fan 200 to the charger 12a is not linear. And so on. For this reason, it is difficult to create a uniform air flow distribution that provides the same wind speed throughout the longitudinal direction of the charger 12a. Therefore, in the airflow distribution in the longitudinal direction of the charger 12a, unevenness of the wind speed of at least 10% or more often occurs.

  FIG. 4 shows the airflow distribution in the longitudinal direction of the charger 12a in the present embodiment, and shows the result of measurement of the wind velocity distribution in the longitudinal direction every 20 mm with the image center at 0 mm. Specifically, the measurement conditions of the wind speed are 2.5 mm above the lower end of the side plate of the shield member 12s of the charger 12a located on the downstream side of the photosensitive drum 11a in FIG. A wind speed sensor was installed at a distance of 5.0 mm. As an anemometer, for example, a value measured using a combination of an anemometer MODEL G-4DP manufactured by Honda Industries, Ltd. and a sensor GeZ-200 DA unit is used as a wind speed.

  According to FIG. 4, the average velocity of the air flow in the entire longitudinal direction in the charger 12a is 1.13 m / s. Further, the wind speed at both ends on the front side and the back side of the charger 12a is the strongest, whereas the central part in the longitudinal direction is the weakest, the wind speed of 1.0 to 1.2 m / s. It has become. Therefore, the airflow distribution in the longitudinal direction in the charger 12a is a distribution in which the wind speed on the front side and the back side of the charger 12a deviates by 10% or more from the average value in the entire longitudinal direction. Moreover, the wind speed unevenness in the whole longitudinal direction in this case is 50% at maximum at 1.0 m / s and 1.5 m / s. The near side is the side for operating the image forming apparatus 600, and the far side is the opposite side.

  The reason why the wind speed at both ends in the longitudinal direction of the charger 12a is increased is to prevent the toner, dust, and the like scattered from the outside of the charger 12a from entering. The measurement points A, B and C in FIG. 4 will be described later.

[Transition of performance by use of grid electrode]
Here, the effect of the grid electrode 12g on the image density when the image formation was repeatedly performed by the charger 12a having the above-described air flow distribution in the longitudinal direction was examined. Specifically, the grid electrode 12g after the output of 30000 sheets of images with an image area of 15% was examined. The image area means an image area in which the laser is emitted by the exposure device 13a and the surface of the photosensitive drum 11a is exposed, and is synonymous with the image ratio.

  As a research, the density distribution of the longitudinal direction of the halftone image output by the grid electrode 12g of the initial stage immediately after the start of use and the halftone image output by the grid electrode 12g after use which output 300000 sheets was compared. In addition, in order to clarify the cause of the investigation, it is assumed that parts other than the grid electrode 12g are in a new state, and when the new grid electrode 12g and the used grid electrode 12g are used, halftone images are obtained. I made an output. The output density on paper as a recording material was measured using a reflection densitometer manufactured by X-rite.

  While the longitudinal density unevenness of the halftone image in the initial grid electrode 12g is Δ0.03, the density unevenness in the longitudinal direction in the halftone image of the grid electrode 12g after output of 300,000 sheets (after use) is Δ0. It was 23. In this survey, since only the grid electrode 12g is replaced with a new one and used to output an image, it is clear that the cause of the uneven density is in the grid electrode.

  When the density distribution of the halftone image after use was examined in detail, the densities at both ends were thinner than in the central portion. That is, the result is that the density on the paper tends to decrease as the wind speed of the air flow in the charger 12a becomes stronger.

  Therefore, the correlation between the density on paper output using the used grid electrode 12g and the air flow in the charger 12a was examined. The results are shown in FIG. According to FIG. 5, it was found that the density on the paper tends to be thinner as the wind speed of the air flow of the charger 12a is stronger.

  As additional investigations regarding this tendency, similar investigations were conducted with several configurations in which the longitudinal distribution of the air flow of the charger 12a was intentionally changed. As a result, it was found that the lower the density on the paper, the stronger the wind speed of the air flow of the charger. Further, as a result of conducting the above-mentioned investigation a plurality of times, it was found that the distribution of density unevenness in the longitudinal direction on the paper caused by the use of the grid electrode 12g does not change significantly unless the air flow of the charger 12a changes significantly. In other words, the places where the concentration became thinner and the places where the concentration became dense were at almost the same position every time. The unevenness in density is caused by the adhesion of the component derived from the toner on the surface of the grid electrode. It was found that as the wind speed of the air flow of the charger is stronger, the component derived from the toner is more attached.

[Toner amount detection sensor]
As described above, the toner amount detection sensor 60 detects the toner amount of the toner image on the intermediate transfer belt 31. In this embodiment, as described later in detail, in order to diagnose a dirty state due to the use of the grid electrode 12g, in the diagnostic mode, a diagnostic toner image, which is a diagnostic developer image, is formed on the intermediate transfer belt 31. . Then, the diagnostic toner image is detected by the toner amount detection sensor 60, and information on the state of the grid electrode 12g is output based on the detected result.

  For this reason, in the present embodiment, a plurality of toner amount detection sensors 60 are disposed at different positions in the width direction (the same as the width direction of the charger 12 a described above) intersecting the rotation direction of the intermediate transfer belt 31. In the present embodiment, in particular, the toner amount detection sensor 60 is disposed at a position in the width direction of the intermediate transfer belt 31 corresponding to at least two of the width direction both ends and the center in the shield member 12s of the charger 12a. It is done.

  Specifically, the toner amount detection sensors 60 are disposed at three locations in the width direction as shown at measurement points A, B and C in FIG. That is, assuming that the image center is 0 mm, the toner amount detection sensor 60 at measurement point A is +160 mm (front side), the toner amount detection sensor 60 at measurement point B is 0 mm (center), and the toner amount detection sensor 60 at measurement point C is It is installed at a position of -160 mm (back). Therefore, a total of three toner amount detection sensors 60 are provided.

  As described above, the wind speed of the air flow of the charger 12a at the 0 mm position (measurement point B) is 1.0 m / s, while the +160 mm position (measurement point A) is 1.4 m / s, -160 mm position (measurement point C) is 1.5 m / s. Further, the average velocity of the air flow in the entire longitudinal direction in the charger 12a is 1.13 m / s. Therefore, in the present embodiment, the toner amount detection sensor 60 is disposed at a position corresponding to a position at which an air flow having a speed different by 10% or more from the average speed in the width direction flows in the air velocity distribution passing through the shield member 12s. It is done. That is, in the present embodiment, the toner amount detection sensor 60 is installed at each of the position where the wind speed is fast and the position where the wind speed is slow with respect to the average value of the wind speed.

  Note that such a toner amount detection sensor 60 may be used also as a sensor for image density correction, a sensor for registration position detection, color misregistration detection, or the like. The toner amount detection sensor 60 may be, for example, two points of measurement points A and B or two points of measurement points B and C.

  The sensor for correcting the image density, for example, detects the density of a control toner image (patch) and controls the amount of replenishment of the developer to the developing device to control the density of the toner image actually formed. To correct the desired concentration. Further, the sensor for detecting the registration position is, for example, for detecting the position in the main scanning direction (width direction) of the patch and correcting the exposure start position by the exposure device. Further, the color misregistration detection sensor detects the position of the patch, whereby the positional deviation of the toner image in the width direction, and the intermediate transfer belt 31 of the toner images of the respective colors transferred onto the intermediate transfer belt 31 in an overlapping manner. Position correction in the direction of rotation of the lens.

[Diagnostic mode of grid electrode]
As described above, when the image formation is repeated, the grid electrode 12 g becomes soiled with components derived from toner and the like. In the present embodiment, the printer control unit 101 (FIG. 2) can execute the diagnostic mode of the grid electrode 12g in order to accurately detect the contamination state of the grid electrode 12g and diagnose the replacement time of the grid electrode 12g and the like. It is.

  In the diagnosis mode, in order to diagnose the state of the grid electrode 12g, a developing method without exposure by the exposure device was used. That is, in the diagnostic mode, the printer control unit 101 charges the surface of the photosensitive drum 11a to a predetermined charging potential by the charger 12a. Then, a diagnostic toner image as a diagnostic developer image is formed on the photosensitive drum 11a by the potential difference between the developing potential applied to the developing device 14a and the predetermined charging potential without exposure by the exposing device 13a. Then, a diagnostic toner image is detected by the toner amount detection sensor 60, and information related to the state of the grid electrode 12g, for example, information related to replacement time, is output based on the detected result.

  Specifically, the printer control unit 101 uses the potential sensor 70 to adjust the voltage applied to the grid electrode 12g such that the surface potential of the photosensitive drum 11a becomes -500 V (predetermined charging potential). Next, with the exposure device 13a turned off, -530 V (development potential) is applied to the development sleeve 142 of the development device 14a as a DC component high voltage. In the case of the present embodiment, the developing bias applied to the developing device 14a is a voltage in which an AC component is superimposed on a DC component. Therefore, also in the diagnostic mode, a voltage in which an AC component is superimposed on a DC component is applied. In the present embodiment, the AC component is set to 1400 V at peak-to-peak Vpp. When the developing device is not configured to apply an AC component in a superimposed manner, a developing bias of a DC component is applied.

  Due to the potential difference between the charging potential -500 V and the developing potential -530 V, a diagnostic toner image is formed on the charged area of the photosensitive drum 11a. The same applies to other image forming units. Thereafter, the diagnostic toner image is transferred onto the intermediate transfer belt 31 (FIG. 1) in the same manner as during normal image formation. In the present embodiment, the amount of toner with which the density on the paper becomes approximately 0.7 with the charging potential and the developing potential described above is placed on the intermediate transfer belt.

  The toner amount (density) of the diagnostic toner image transferred onto the intermediate transfer belt 31 is detected by three toner amount detection sensors 60 disposed at measurement points A, B and C. The printer control unit 101 diagnoses the contamination state of the grid electrode 12g based on the detection result, for example, diagnoses the replacement time. In this embodiment, the replacement timing of the grid electrode 12g is calculated from the detected concentration difference. Specifically, the maximum value and the minimum value are extracted from the detection results obtained by detecting the toner image for diagnosis by the three toner amount detection sensors 60 at the measurement points A, B, and C, and the maximum value and the minimum value are extracted. Calculate the difference (density difference). Then, based on the concentration difference, the grid electrode replacement time is predicted. This point is described below. Thereafter, the diagnostic toner transferred onto the intermediate transfer belt 31 is collected by the cleaning unit 50 (FIG. 1).

[Prediction of grid electrode replacement time]
Next, a method of predicting the grid electrode replacement time based on the above-mentioned concentration difference will be described. FIG. 6 shows the replacement timing of the grid electrode 12g from the transition of the density difference between the maximum value and the minimum value when the diagnostic toner image is detected at the measurement points A, B, C under conditions 1 and 2 To predict the That is, an image is actually formed by the image forming apparatus under conditions 1 and 2, a diagnostic toner image is formed for each predetermined number of sheets, and the diagnostic toner image is measured by the toner amount detection sensor 60 at measurement points A, B and C. Detected. Then, the maximum value and the minimum value among the detection results were extracted, and the difference (density difference) between the maximum value and the minimum value was calculated.

  Condition 1 is a transition of density difference when an image having an image area of 5 to 20% is formed up to 450 k (450 × 1000) sheets. Condition 2 is a transition of density difference when an image having an image area of 35 to 50% is formed up to 100 k (100 × 1000) sheets. The environment in which the image forming apparatus is installed under conditions 1 and 2 is 23 ° C. and 20%. As is clear from FIG. 6, it was found that the density difference with respect to the number of sheets for image formation shows a substantially linear transition under both the conditions 1 and 2.

  Here, the value of the density difference at which the grid electrode 12 g is replaced is taken as a density difference threshold Z. In the present embodiment, since the assumed user using the image forming apparatus of the present embodiment often replaces the grid electrode 12g when the density difference exceeds approximately 0.1, the density difference threshold value Z = 0.1 and did. That is, from the data transition of the density difference with respect to the number of sheets for image formation, the number of sheets for image formation at which the density difference threshold Z becomes 0.1 is predicted as the replacement timing of the grid electrode 12g. In FIG. 6, about 700 k sheets of the condition 1 are predicted as the replacement timing of the grid electrode 12 g, and about 200 k sheets of the condition 2 are predicted as the replacement timing of the grid electrodes 12 g.

[Diagnostic flow of grid electrode]
Next, the flow of the diagnostic mode of the grid electrode 12g in the present embodiment will be described with reference to FIG. The diagnosis method of the grid electrode of the present embodiment is roughly divided into a toner image for diagnosis and a toner amount detection sensor 60 based on a first step of detecting the toner image for diagnosis and a result of detection in the first step. And a second step of diagnosing the replacement time of the grid electrode 12g. Hereinafter, the diagnosis mode of the present embodiment will be specifically described.

  The printer control unit 101 can execute the diagnostic mode at a predetermined timing. Specifically, the execution timing of the diagnosis mode of the grid electrode was set for every 50000 sheets of image formation. That is, when an image forming job is executed after an image has been output 50000 sheets or more since the previous execution of the grid electrode diagnostic mode, the diagnostic mode at the time of the preparation operation for the start of the image formation job and the preparation for the end Run.

  The image formation job is a period from the start of image formation to the completion of image formation based on a print signal (image formation signal) for forming an image on a recording material. That is, in the image forming job, a series of operations of the pre-operation (preparation operation) performed before the image forming operation, the image forming operation, and the post operation (end preparation operation) performed after the image forming operation It is a period to carry out.

  Even if 51000 or more images have been output since the previous execution of the diagnosis mode, if the start preparation operation and the end preparation operation do not enter, the grid electrode diagnosis mode is forcibly executed. For example, the image forming operation is interrupted to execute the diagnostic mode. The diagnostic mode may be executed in parallel with the preparation operation when the power of the image forming apparatus is turned on or when another control is operating. That is, in accordance with the average replacement timing of the grid electrodes, it is preferable to execute the diagnostic mode at a timing or interval at which the decrease in productivity of the image forming apparatus is not felt as much as possible.

  In FIG. 7, when the execution timing (predetermined timing) of the diagnostic mode of the grid electrode is reached, the diagnostic mode is started. Once started, as described above, a diagnostic toner image is formed on the intermediate transfer belt 31 (S1). Then, the toner amount detection sensor 60 detects a diagnostic toner image at measurement points A, B, C, and grasps the respective toner amount detection results (density) (S2). The result detected by the toner amount detection sensor 60 is stored in the memory 101 b (FIG. 2) of the printer control unit 101.

  Next, the CPU 101a of the printer control unit 101 calculates the grid electrode replacement timing from the detected density difference as described with reference to FIG. 6 (S3). That is, the maximum value and the minimum value are extracted from the toner amount detection results of the three measurement points A, B, and C, and the density difference between the maximum value and the minimum value is calculated. Then, the calculated density difference data is stored in the memory 101b. The memory 101 b can store density difference data of the past. The CPU 101a predicts the next replacement timing of the grid electrode 12g from the density difference data stored in the memory 101b and the density difference data added this time, that is, from the transition of the density difference data.

  Next, the predicted grid electrode replacement timing is stored as the latest data in the memory 101b (S4). Then, the CPU 101a compares the magnitude relation between the image formation number X up to the predicted replacement timing of the grid electrode 12g and the image formation number Y necessary for preparation until the grid electrode 12g is replaced (S5).

  Here, with the number of image formations Y necessary for preparation before replacing the grid electrode, the user exchanges the average number of image formations per day and the new grid to be replaced to the place where the image forming apparatus is installed. The number is determined in consideration of the number of days. In the present embodiment, Y is set to 100 k (100 × 1000).

  For example, under the condition 1 shown in FIG. 6 described above, the next grid electrode replacement timing is expected to be about 700 k, and the current number of image formation is 450 k, so the next grid electrode replacement timing The number of formed images X = 350 k. On the other hand, under condition 2, the next grid electrode replacement timing is expected to be approximately 200 k, and the current image formation number is 150 k sheets, so the image formation number X up to the next grid electrode replacement timing X = 50 k sheets It becomes.

  Therefore, since the condition 1 is X = 350 k sheets and Y = 100 k sheets in S5, the relationship of X> Y is established, and the process proceeds to S6 to continue the image forming operation. On the other hand, since condition 2 is X = 50 k sheets and Y = 100 k sheets, the relationship of X> Y does not hold, so the process proceeds to step S7.

  At S7, the user is informed that the replacement timing of the grid electrode 12g is approaching. For example, the printer control unit 101 outputs that the replacement timing of the grid electrode 12g is approaching as information related to the state of the grid electrode, and causes the operation display unit 108 (FIG. 2) to display it. FIG. 8 is an example of a screen displayed on the operation display unit 108 for notifying the user of grid electrode replacement. The contents of the screen of FIG. 8 may be displayed on a personal computer connected to the image forming apparatus, for example, in addition to the operation display unit 108, or may be notified to an external data center.

  As shown in FIG. 8, the screen notifying of grid electrode replacement includes a confirmation button 108 a for confirming / accepting the content. The user temporarily decides to replace the grid electrode by pressing the confirmation button 108a (S8). Although FIG. 8 illustrates only a simple confirmation button, it presents candidate dates for grid electrode replacement and allows the user to specify a grid replacement scheduled date according to the operation status of the device. You may Thereafter, the process proceeds to step S6, and the image forming operation is continued to end the diagnostic mode.

  In the case of such this embodiment, the state of the grid electrode 12g can be diagnosed more accurately. As described above, in the present embodiment, in the diagnostic mode, the diagnostic toner image is formed by the potential difference between the development potential and the charging potential without exposure by the exposure device. Therefore, the influence of the contamination condition of the grid electrode is easily reflected on the diagnostic toner image.

  Further, the toner amount detection sensor 60 for detecting a diagnostic toner image has a position corresponding to a position where an air flow having a speed different by 10% or more from the average speed in the width direction flows in the velocity distribution of the air passing through the shield member 12s. Is located in As described above, the density of the formed image is affected by the velocity distribution of the air flow in the shield member 12s, and the component derived from the toner adheres to the grid electrode 12g as the wind speed is stronger, and the density becomes thinner. Therefore, by detecting the amount of toner by the toner amount detection sensor 60 at the position corresponding to the position where the air flow different by 10% or more from the average speed flows, it becomes easy to detect the degree of contamination of the grid electrode 12g.

  In particular, by using the density difference between the maximum value and the minimum value among the toner amount detection results in the diagnosis mode, it is possible to more accurately predict the transition of the degree of contamination of the grid electrode 12g with respect to the number of image formation. That is, when the component derived from the toner adheres to the grid electrode 12g, the density of the toner image to be formed is reduced, so that if the density difference is large, the grid electrode 12g is soiled. Therefore, by observing the transition of the concentration difference, the state of the grid electrode 12g, that is, the degree of contamination can be diagnosed more accurately.

  Then, if it is possible to accurately grasp the degree of contamination of the grid electrode 12g in this manner, it is possible to appropriately output the replacement time of the grid electrode 12g (in the present embodiment, display on the operation display unit 108). As a result, the grid electrode 12g can be replaced at an appropriate time, and it can be suppressed that the grid electrode 12g is replaced even though it can be used, or the grid electrode 12g is not replaced when the replacement time is over. In addition, if the grid electrode 12g can be replaced at an appropriate time, it is possible to prevent a decrease in productivity due to the replacement of the grid electrode 12g and the occurrence of image defects caused by the grid electrode 12g.

  As information on the state of the grid electrode 12g, for example, the degree of contamination may be indicated. When it is determined that the grid electrode 12g is dirty quickly, the cleaning frequency of the grid electrode 12g can be increased to prevent the grid electrode from being dirty, and the replacement timing of the grid electrode 12g can be extended.

  Further, in the above description, the amounts of toner at a plurality of points having different wind speeds of the air flow in the charger 12a are detected, and the replacement timing of the grid electrode 12g is predicted from the density difference. However, the replacement timing of the grid electrode 12g may be predicted from the result of detecting the amount of toner at one location shifted from the average value of the airflow velocity in the longitudinal direction in the charger 12a. For example, the toner amount detection sensor 60 is disposed at one of the measurement points A and C. That is, the toner amount is detected at a position corresponding to the position where the air flow having a speed different by 10% or more from the average speed in the width direction of the charger 12a flows. Then, the replacement timing of the grid electrode is predicted by comparing the detected toner amount (density) with a predetermined toner amount (threshold).

Second Embodiment
A second embodiment will be described using FIG. 9 with reference to FIGS. 1 to 3. In the first embodiment described above, the information regarding the replacement time of the grid electrode 12g is displayed on the operation display unit 108 of the image forming apparatus 600. On the other hand, in the present embodiment, the information detected in the diagnostic mode is transmitted to the external data center 601, and the data center 601 diagnoses the replacement time of the grid electrode 12g. The other configurations and actions are the same as those of the above-described first embodiment, and thus overlapping descriptions and illustrations are omitted or simplified, and hereinafter, differences from the first embodiment will be mainly described.

  In the case of the present embodiment, as shown in FIG. 9, an image forming system 610 is configured by the image forming apparatus 600 and the data center 601. The image forming system 610 further includes a maintenance center 602 and a parts delivery center 603. Then, within the image forming system 610, exchange of grid electrode replacement timing information predicted in the grid electrode diagnostic mode is performed.

  FIG. 9 is a block diagram of information transmission from the image forming apparatus 600. As shown in FIG. As shown in FIG. 9, the image forming apparatus 600 is connected to a personal computer (PC) 604 that displays image information input to the image forming apparatus 600, the operating status of the image forming apparatus 600, and the like. The image forming apparatus 600 is connected to an external data center 601 via the Internet or the like. To this end, the image forming apparatus 600 includes a transmitting / receiving unit 600a as a transmitting unit capable of transmitting information to the outside, and the data center 601 also includes a transmitting / receiving unit 601a. The transmitting and receiving units 600 a and 601 a can transmit and receive information, respectively, and can thereby exchange information between the image forming apparatus 600 and the data center 601.

  The data center 601 collects density difference data processed in the image forming apparatus 600, data on grid electrode replacement timing, data on actual grid electrode replacement timing, and the like. The data center 601 is connected to a maintenance center 602 having a worker who maintains the image forming apparatus 600, a parts delivery center 603 for delivering replacement parts, and the like via the Internet or the like. Therefore, the maintenance center 602 also has a transmission / reception unit 602a, and the component delivery center 603 also has a transmission / reception unit (not shown).

  In the present embodiment, the printer control unit 101 of the image forming apparatus 600 transmits density difference data detected by the toner amount detection sensor 60 in the diagnosis mode to the data center 601 by the transmission / reception unit 600 a. The data center 601 has a CPU 601 b as a diagnosis unit, and the CPU 601 b diagnoses the grid electrode replacement timing from the density difference data sent from the image forming apparatus 600 as in the first embodiment. Then, the data center 601 transmits the information to the parts delivery center 603 and the maintenance center 602 by the transmitting / receiving unit 601 a.

  At the maintenance center 602, the transmitted information is received by the transmission / reception unit 602a. The maintenance center 602 has a CPU 602b as a determination means, and based on this information, the CPU 602b plans maintenance of grid electrode replacement (ie, delivery date of grid electrode for replacement) and grid electrode replacement. Determine the dispatch date of maintenance workers. That is, in the present embodiment, the image forming apparatus 600 executes a first process of forming a diagnostic toner image and detecting the diagnostic toner image by the toner amount detection sensor 60. Next, the delivery date of the grid electrode for replacement is determined based on the second step of diagnosing the grid electrode replacement time based on the result detected in the first step and the grid electrode replacement time diagnosed in the second step. The third process to be performed is executed in the data center 601.

  Information such as the delivery date determined by the maintenance center 602 is sent to the parts delivery center 603, and the parts delivery center 603 starts delivery of grid electrodes for replacement. That is, the maintenance center 602 and the parts delivery center 603 are also connected so that they can exchange information, and can exchange the delivery status of parts, dispatch information of workers, and the like.

  As described above, in the present embodiment, since the data center 601 diagnoses the grid electrode replacement time and determines the delivery date of the replacement grid electrode, the grid electrode can be replaced smoothly. In particular, by sending information from the data center 601 to the parts delivery center 603, delivery of replacement grid electrodes and dispatch of workers can be performed automatically.

  Further, the data center 601 may exchange the grid electrode at the most convenient timing for the user by collating the operation status of the image forming apparatus 600 of the user and the like. When the grid electrode replacement operation is simple, only the delivery of parts may be performed, and the user may be requested to perform the replacement operation without dispatching a maintenance worker.

  Further, in the above description, diagnosis of grid electrode replacement time is performed in the data center 601, but the image forming apparatus 600 diagnoses grid electrode replacement time in the same manner as in the first embodiment. You may send it. That is, the printer control unit 101 doubles as a diagnostic unit to diagnose the grid electrode replacement time, and the transmitting / receiving unit 600a transmits the diagnosis result of the grid electrode replacement time to the data center 601 as information on the grid electrode. Also good.

Data Analysis in Data Center
Next, data analysis in the external data center 601 will be described. The data center 601 is connected to image forming apparatuses installed at various places. In the data center 601, in addition to the data described above, the installation environment of the image forming apparatus, the image area, the number of images formed for each type of recording material (such as plain paper, thick paper, thin paper, etc.), replacement status of replacement parts other than grid electrodes And other data are collected.

  Here, analysis of grid replacement timing data of the image forming apparatus installed in various places showed that the installation environment of the image forming apparatus affected the degree of influence of the toner-derived component attached to the grid electrode. . Also, it was found that the amount of the toner-derived component adhering to the grid electrode tends to increase as the image area is larger. In addition to the image area, it was found that if the air supply and exhaust filters other than the charger are dirty, the grid electrode tends to be dirty.

  From these analysis results, the degree of contribution of the grid electrode to the contamination is large in the installation environment of the image forming apparatus and the image area, and the replacement timing of the grid electrode can be predicted to some extent from these two items. However, there may be a user whose grid electrode replacement timing is significantly shorter than expected. In that case, the assumed cause is notified to the maintenance center 602 and the image forming apparatus 600.

  An example of notification is shown below. Specifically, the exhaust filter of the fixing unit is used far beyond the replacement standard, and the air flow warmed by the fixing unit is difficult to be discharged out of the main body, and a part of the air flow flows into the charger. , There was a case that was affecting the grid electrode.

  Therefore, replacement parts that affect the contamination of the grid electrode are listed. And, if those replacement parts are not replaced at appropriate replacement timing, the target replacement part is being used beyond the replacement standard and there is a possibility that the contamination of the grid electrode may be affected. Notice.

  In other cases, there was a smoking area near the image forming apparatus, smoke from the smoking area was supplied to the image forming apparatus, and the grid electrode was contaminated by the smoke component. In the same case, the grid electrode may be soiled by volatile components of the drug used in the vicinity of the image forming apparatus. In these cases, suspended matter is present around the image forming apparatus to notify that the grid electrode may be dirty.

  The notification may be separately performed according to the content of the notification, in the case of notifying only the maintenance center 602, in the case of notifying the maintenance center 602 and the image forming apparatus 600, and according to the content of the notification. If it is an item that can improve the content of the notification, it can be improved, and if it can not be improved according to the user's situation, the worker of the maintenance center inputs it to the data center. Then, by considering the past grid electrode replacement results, it is possible to predict grid electrode replacement timing according to the user's situation for the corresponding image forming apparatus.

  Further, even in the case where the replacement timing of the grid electrode does not become significantly shorter than predicted, the image quality to be obtained differs depending on the user and the image area is different. For this reason, the density difference threshold Z described above, the number X of image formations up to the replacement timing of the grid electrodes, and the number Y of images formation required for the preparation up to replacement of the grid electrodes differ depending on the user.

  Therefore, X, Y, and Z may be determined with reference to the exchange results of users who use similar methods. Since the installation environment of the image forming apparatus affects, X, Y, and Z may be determined in consideration of the annual weather change at the installation site.

  When there is a cleaning member on the grid electrode, the grid electrode replacement timing may be determined in consideration of the dirt recovery factor of the grid electrode by the grid cleaning.

  The analysis at the data center 601 such as determination of X, Y, and Z and grid cleaning may be performed by the image forming apparatus 600.

Third Embodiment
A third embodiment will be described using FIG. 10 with reference to FIGS. 1 to 3. In the above-described first embodiment, the diagnosis mode of the grid electrode is executed at a predetermined timing (every 50000 sheets). On the other hand, in the present embodiment, the image area for each image formation is integrated, and when the integrated value reaches a predetermined value, the diagnosis mode can be executed. The other configurations and actions are the same as those of the above-described first embodiment, and thus overlapping descriptions and illustrations are omitted or simplified, and hereinafter, differences from the first embodiment will be mainly described.

  The grid electrode is more easily soiled as the formed image area is larger. For this reason, as in the first embodiment, when the diagnostic mode is executed at a predetermined timing, the diagnostic mode is not executed even when the grid electrode is dirty but not executed, or the grid electrode is not dirty. There is a possibility of execution.

  Therefore, in the present embodiment, the diagnosis mode is executed according to the integrated value of the image area. Specifically, the diagnostic mode of the grid electrode is executed when the integration area (predetermined value) for 40,000 images of an image area of 15% of the A3 size image is reached. Further, in the present embodiment, the diagnostic mode of the grid electrode is executed when an image forming unit among the image forming units 10a, 10b, 10c, and 10d reaches the above-described integrated area. As a result, the diagnosis mode of the grid electrode can be executed at an appropriate timing, and the decrease in productivity and toner consumption due to the execution of the diagnosis mode can be suppressed.

  Here, there are cases where it is desirable to prevent a decrease in productivity even if the time required for the diagnostic mode is several seconds, and when it is desirable to carry out continuous image forming jobs. For this reason, in the present embodiment, it is possible to select whether the diagnostic mode of the grid electrode is periodically and automatically executed, manually executed, or not executed. That is, it is possible to select whether or not to execute the diagnostic mode. For this purpose, in the present embodiment, the operation display unit 108, which is also a selection unit, can select whether or not to execute the diagnostic mode. Specifically, a selection screen regarding the execution of the diagnostic mode is displayed on the operation display unit 108 so that the user can select.

  FIG. 10 shows an example of a selection screen regarding execution of the diagnostic mode of the grid electrode displayed on the operation display unit 108. When the user presses the operation button 108b in FIG. 10 on this screen, the diagnostic mode is automatically executed according to the integrated value of the image area as described above. When the user presses the operation button 108c, the diagnostic mode is executed regardless of the integrated value of the image area. When the user presses the operation button 108d, for example, the diagnostic mode is not executed until the user cancels this operation. Specifically, the diagnosis mode may not be executed until the selection screen of FIG. 10 is periodically displayed and the user presses the operation buttons 108b and 108c, or the diagnosis mode is performed until the number of formed images reaches a predetermined number. May not be performed. When the diagnosis mode is automatically performed, the diagnosis mode may be executed at a predetermined timing as in the first embodiment.

  In addition, the operation display unit 108 may select whether to notify the data center of the diagnosis result in consideration of reducing the load on the image forming apparatus not connected to the network or the network. .

  Further, the configuration of the present embodiment may be applied to the image forming system of the second embodiment. That is, density difference data detected by the toner amount detection sensor 60 in the diagnosis mode of the present embodiment is transmitted to the data center 601 by the transmission / reception unit 600a. The CPU 601b of the data center 601 may diagnose the grid electrode replacement time from the density difference data sent from the image forming apparatus 600 as in the first embodiment (see FIG. 9). When the present embodiment is applied to the image forming system of the second embodiment, the image forming apparatus may diagnose the replacement time of the grid electrode and transmit the diagnosis result to the data center.

Fourth Embodiment
A fourth embodiment will be described using FIG. 11 with reference to FIGS. 1 to 3. In the first embodiment described above, the diagnosis toner image is transferred to the intermediate transfer belt 31 in the diagnosis mode, and the toner amount detection sensor 60 detects the diagnosis toner image to diagnose the replacement time of the grid electrode. On the other hand, in the present embodiment, the diagnostic toner image is output to the recording material. The other configurations and actions are the same as those of the above-described first embodiment, and thus overlapping descriptions and illustrations are omitted or simplified, and hereinafter, differences from the first embodiment will be mainly described.

  In the first embodiment described above, the toner amount detection sensor measures the density unevenness in the main scanning direction (width direction) of the diagnostic toner image. As described above, if the toner amount detection sensor is used, density unevenness can be automatically detected, but only the detection area of the sensor can detect density unevenness. Depending on the user, there are also users who are concerned about uneven density in the entire image other than the detection area of the sensor. Therefore, in the present embodiment, a diagnostic toner image formed in the diagnostic mode is output on the recording material.

  FIG. 11 is an image of a diagnostic mode of the grid electrode output on a sheet of paper as a recording material. The image on paper is output in a size A3 or larger as shown in FIG. 11, and a diagnostic toner image developed by the potential difference between the charge potential and the development potential is printed without using an exposure device of 7 to 9 cm for each color. ing. The conditions for forming a diagnostic toner image are the same as in the first embodiment. FIG. 11 also shows diagnostic toner images for yellow, magenta, cyan and black from the top.

  Here, the image output on the paper is a toner image for which the exposure device is not used, and therefore differs from the normal image. Therefore, the user may misunderstand that the device is broken. For this reason, in the present embodiment, an image is printed on a sheet of paper, together with a diagnostic toner image, which is an image for a diagnostic mode and indicates that the apparatus is not abnormal.

  That is, in the diagnostic mode of the present embodiment, the printer control unit 101 forms a diagnostic toner image by the potential difference between the developing potential and the charging potential without performing exposure by the exposure device. At this time, a toner image to the effect that the diagnostic toner image does not indicate an abnormality of the apparatus is also formed, and is transferred onto the recording material by the intermediate transfer unit 30 together with the diagnostic toner image. The transferred diagnostic toner image and the toner image to the effect that the image does not indicate abnormality of the apparatus are fixed to the recording material by the fixing unit 40 and output. As a result, it is displayed on the recording material on which the diagnostic toner image is formed that the diagnostic toner image does not indicate an abnormality of the apparatus.

  The display indicating that there is no abnormality in the apparatus may be performed by performing two image forming operations in order to form an image indicating that there is no abnormality after the diagnostic toner image is formed. In addition to the formation as a toner image, for example, a printing apparatus may be separately provided on the downstream side of the fixing unit 40 for printing.

  The recording material (paper) on which the diagnostic toner image is formed as described above is read by, for example, the image reading unit 1R included in the image forming apparatus 600 or a dedicated scanner to detect density unevenness in the main scanning direction. Also good. Then, it is possible to diagnose the replacement time of the grid electrode from the uneven density. For example, the printer control unit 101 may perform this diagnosis from the data of uneven density, or may transmit this data to the data center 601 as in the second embodiment and make a diagnosis at the data center 601. Alternatively, even if the user or the service person visually checks the recording material on which the diagnostic toner image is formed and determines the degree of contamination of the grid electrode, etc., the grid electrode may be replaced as necessary. good.

  According to the present embodiment, the condition of the grid electrode can be diagnosed without using the toner amount detection sensor, and the decrease in productivity of the image forming apparatus upon replacement of the grid electrode can be prevented as much as possible. it can.

Other Embodiments
The present invention is applicable to an image forming apparatus using an electrostatic recording system or an electrophotographic system in which an electrostatic image formed on an image carrier is developed with a developer. Further, as an image forming apparatus to which the present invention can be applied, in addition to a printer, a copying machine, a facsimile, a multifunction machine, etc. may be mentioned.

  In each of the above-described embodiments, the information regarding the state of the grid electrode is the information regarding the replacement time of the grid electrode. For example, the contamination condition of the grid electrode and the charger itself are exchanged as this information. It may be information to the effect. Further, the information to be displayed or transmitted based on this information may be, for example, information prompting to call a service person, in addition to the indication.

  11a, 11b, 11c, 11d ... photosensitive drum (image carrier) / 12a, 12b, 12c, 12d ... charger (charging unit) / 12g ... grid electrode (control electrode) / 12s ... Shield member (housing) / 12w Wire member (discharge electrode) / 13a, 13b, 13c, 13d Exposure device (exposure means) / 14a, 14b, 14c, 14d Development device (developing means Intermediate transfer unit (transfer means) / 40 Fixing unit (fixing means) / 60 Toner amount detection sensor (developer image detection means) / 101 Printer control unit (executed) Means) / 101b ... memory (storage means) / 108 ... operation display unit (display means, selection means) / 210 ... air flow forming unit (air flow forming unit) / 600 ... image forming apparatus / 600a ... Receiver (transmission means) / 601b ... CPU (diagnosing means) / 602b ... CPU (determination means) / 610 ... imaging system

Claims (16)

A rotating image carrier,
A housing open on the side facing the image carrier, a discharge electrode disposed in the housing and discharging when a voltage is applied, and a position closer to the image carrier than the discharge electrode of the housing A charging unit having a control electrode to which a voltage is applied, and charging the surface of the image carrier;
Air flow forming means for forming an air flow passing through the inside of the housing;
An exposure unit that exposes the surface of the image bearing member charged by the charging unit to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the surface of the image bearing member with a developer;
In the velocity distribution of the air flow passing through the inside of the housing, the developing means is disposed at a position corresponding to a position where an air flow having a speed different by 10% or more with respect to the average speed in the width direction intersecting the rotation direction of the image carrier Developer amount detecting means capable of detecting the developer amount of the developer image developed by the developer;
Storage means for storing the detection result of the developer amount detection means;
The surface of the image carrier is charged to a predetermined charging potential by the charging unit, and the image is formed by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential without performing exposure by the exposure unit. It is possible to execute a diagnostic mode in which a diagnostic developer image is formed on a carrier, the diagnostic developer image is detected by the developer amount detecting means, and information on the state of the control electrode is output based on the detected result. With various means of execution,
An image forming apparatus characterized by The plurality of developer amount detecting means are disposed at different positions in the width direction,
The execution means outputs information related to the state of the control electrode based on the difference between the maximum value and the minimum value among the detection results obtained by detecting the diagnostic developer image by the plurality of developer amount detection means. ,
The image forming apparatus according to claim 1, characterized in that: The plurality of developer amount detecting means are disposed at positions corresponding to at least two of the widthwise end portions and the central portion in the housing.
The image forming apparatus according to claim 2, characterized in that: The execution means can execute the diagnostic mode at a predetermined timing.
The image forming apparatus according to any one of claims 1 to 3, characterized in that: The execution means integrates the image area every image formation, and can execute the diagnostic mode when the integrated value reaches a predetermined value.
The image forming apparatus according to any one of claims 1 to 3, characterized in that: It has selection means capable of selecting whether to execute the diagnostic mode or not.
The image forming apparatus according to any one of claims 1 to 5, characterized in that: The execution means is information on the state of the control electrode from the result of detection by the developer amount detection means in the diagnosis mode by the previous time and the result of detection by the developer amount detection means in the current diagnosis mode. Output
The image forming apparatus according to any one of claims 1 to 6, characterized in that: A display unit for displaying information on the state of the control electrode output by the execution unit;
The image forming apparatus according to any one of claims 1 to 7, characterized in that: A transmitting unit capable of transmitting information on the state of the control electrode output by the executing unit to the outside;
An image forming apparatus according to any one of claims 1 to 8, characterized in that. The information on the state of the control electrode is information on the replacement time of the control electrode,
The image forming apparatus according to any one of claims 1 to 9, characterized in that: A rotating image carrier,
A housing open on the side facing the image carrier, a discharge electrode disposed in the housing and discharging when a voltage is applied, and a position closer to the image carrier than the discharge electrode of the housing A charging unit having a control electrode to which a voltage is applied, and charging the surface of the image carrier;
An exposure unit that exposes the surface of the image bearing member charged by the charging unit to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the surface of the image bearing member with a developer;
A transfer unit for transferring the developer image developed by the developing unit onto a recording material;
Fixing means for fixing the developer image on the recording material to which the developer image has been transferred by the transfer means;
The surface of the image carrier is charged to a predetermined charging potential by the charging unit, and the image is formed by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential without performing exposure by the exposure unit. The recording is performed when the diagnostic developer image formed on the carrier is transferred to the recording material by the transfer unit, and the transferred diagnostic developer image is fixed to the recording material by the fixing unit and output. An execution means capable of executing a diagnostic mode for causing the material to indicate that the diagnostic developer image is not indicative of an abnormality of the apparatus;
An image forming apparatus characterized by An air flow forming means for forming an air flow passing through the inside of the housing;
The image forming apparatus according to claim 11, characterized in that: An image forming system comprising an image forming apparatus and diagnostic means, comprising:
The image forming apparatus is
A rotating image carrier,
A housing open on the side facing the image carrier, a discharge electrode disposed in the housing and discharging when a voltage is applied, and a position closer to the image carrier than the discharge electrode of the housing A charging unit having a control electrode to which a voltage is applied, and charging the surface of the image carrier;
Air flow forming means for forming an air flow passing through the inside of the housing;
An exposure unit that exposes the surface of the image bearing member charged by the charging unit to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the surface of the image bearing member with a developer;
In the velocity distribution of the air flow passing through the inside of the housing, the developing means is disposed at a position corresponding to a position where an air flow having a speed different by 10% or more with respect to the average speed in the width direction intersecting the rotation direction of the image carrier Developer amount detecting means capable of detecting the developer amount of the developer image developed by the developer;
The surface of the image carrier is charged to a predetermined charging potential by the charging unit, and the image is formed by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential without performing exposure by the exposure unit. An execution unit capable of executing a diagnostic mode in which a diagnostic developer image is formed on a carrier and the diagnostic developer image is detected by the developer amount detection unit;
Transmitting means for transmitting information detected in the diagnostic mode;
The diagnostic means receives the information transmitted from the transmission means, and diagnoses the replacement time of the control electrode based on the information.
An image forming system characterized by A determination unit configured to determine a delivery date of the control electrode for replacement based on the replacement timing of the control electrode diagnosed by the diagnostic unit;
The image forming system according to claim 13, characterized in that. A rotating image carrier,
A housing open on the side facing the image carrier, a discharge electrode disposed in the housing and discharging when a voltage is applied, and a position closer to the image carrier than the discharge electrode of the housing A charging unit having a control electrode to which a voltage is applied, and charging the surface of the image carrier;
Air flow forming means for forming an air flow passing through the inside of the housing;
An exposure unit that exposes the surface of the image bearing member charged by the charging unit to form an electrostatic latent image;
Developing means for developing the electrostatic latent image formed on the surface of the image bearing member with a developer;
In the velocity distribution of the air flow passing through the inside of the housing, the developing means is disposed at a position corresponding to a position where an air flow having a speed different by 10% or more with respect to the average speed in the width direction intersecting the rotation direction of the image carrier And a developer amount detection means capable of detecting a developer amount of a developer image developed by the control method, wherein the control electrode diagnosis method diagnoses replacement time of the control electrode of the image forming apparatus,
The surface of the image carrier is charged to a predetermined charging potential by the charging unit, and the image is formed by the potential difference between the developing potential applied to the developing unit and the predetermined charging potential without performing exposure by the exposure unit. A first step of forming a diagnostic developer image on a carrier, and detecting the diagnostic developer image by the developer amount detecting means;
And a second step of diagnosing the replacement time of the control electrode based on the result detected in the first step.
Method of diagnosis of control electrode characterized in that. And a third step of determining a delivery date of the control electrode for replacement based on the replacement timing of the control electrode diagnosed in the second step.
The diagnostic method of the control electrode according to claim 15, characterized in that.

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