JP4546552B2 - Image forming apparatus - Google Patents

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as a copying apparatus, a printer, or a facsimile that employs an electrophotographic system or an electrostatic recording system, and particularly develops an electrostatic latent image formed on an image carrier with a one-component developer. The present invention relates to an image forming apparatus.

  Conventionally, an image forming apparatus employing an electrophotographic method exposes the surface of an image carrier to form an electrostatic latent image based on image information, and applies toner from the developing device to the formed electrostatic latent image. And an electrostatic latent image is developed as a toner image. The toner image formed on the surface of the image carrier is transferred to a recording material in a transfer portion and fixed in a fixing device, whereby a desired image can be formed on the recording material.

  In such an image forming apparatus, a dry developing method is widely used as a developing method for developing toner by supplying toner to an electrostatic latent image formed on the surface of an image carrier. Furthermore, it is known that dry development methods include a two-component development method using a two-component developer provided with a toner and a carrier, and a one-component development method using a one-component developer consisting essentially of toner. Yes. In recent years, one-component development systems that do not use a carrier have been widely employed because they are advantageous in reducing the size of the apparatus and reducing costs.

  The one-component development method is classified into a magnetic one-component development method and a non-magnetic one-component development method. The magnetic one-component development system is a development system that uses electrostatic force and magnetic force to hold the toner on the developer carrier. On the other hand, the non-magnetic one-component development system is a development system that uses substantially only electrostatic force to hold the toner on the developer carrying member.

  Comparing the magnetic one-component development method with the non-magnetic one-component development method, the non-magnetic one-component development method that does not require magnetic field generation means can be made simpler, thus reducing the weight and cost. Is possible. Note that it is also possible to distinguish the one-component development method based on the contact state (contact or non-contact) between the image carrier and the developer carrier.

  For example, a metal sleeve such as aluminum or SUS stainless steel is used for the image carrier used in the one-component development method. For the developer carrying member, for example, a metal sleeve whose surface is coated with a resin layer, or an elastic rubber roller in which a conductive agent such as carbon is dispersed in silicone rubber, NBR, EPDM, or the like is used.

  In addition, a regulating blade (developer layer thickness regulating member) that abuts on the surface of the developer carrier is used as a charging unit that forms a toner layer on the developer carrier and further charges the toner on the developer carrier. Is generally used.

  The regulating blade is configured to be pressed and rubbed against the surface of the developer carrying member, and is formed by an elastic member. For example, an elastic blade such as urethane rubber or silicone rubber, or a metal blade such as SUS stainless steel or phosphor bronze is used.

  Next, a one-component toner used in the one-component development method will be described. The one-component toner includes toner base particles and an external additive attached to the surface of the toner base particles. The adhesion of the one-component toner varies greatly depending on the material of the external additive, the particle size, and the surface treatment method.

When the developing device is used for a long period of time, the external additive is released from the surface of the toner base particles, or the external additive is embedded in the toner base particles. Such a state is hereinafter referred to as toner deterioration in the present invention.

  When the toner is deteriorated, the effect of the external additive on the surface of the one-component toner is reduced, the adhesion force of the toner is increased, and there is a problem that the toner is easily fused to each member in the developing device. Here, examples of the members in the developing device include a developer carrying member that carries toner, and a developer layer thickness regulating member such as a regulating blade.

  For example, when the toner is fused to the developer carrying member, the toner adheres excessively to the toner fused portion on the developer carrying member to generate uncharged toner that is not sufficiently charged. Uncharged toner adheres to the white background of the image on the carrier. As a result, an image defect called “fogging” in which toner adheres to the white background portion of the image on the image carrier occurs.

  In addition, when toner is fused to the developer layer thickness regulating member, uncharged toner that is not sufficiently charged is likely to be generated on both sides in the longitudinal direction of the toner fused portion of the developer layer thickness regulating member. The toner adheres to the white background portion of the image on the image carrier. And "covering" occurs.

  As described above, when deteriorated toner is generated in the process of using the image forming apparatus and the toner is fused to each member in the developing device, uncharged toner is generated from the fused portion, and “fogging” is likely to occur. Therefore, in order to obtain stable image quality over a long period of time, there is a need for a means for preventing them from fusing to each member in the developing device even when deteriorated toner is generated.

  Here, in the process of using the image forming apparatus, the deterioration of the toner is detected to prevent the deteriorated toner from fusing to each member (developer carrier, developer layer thickness regulating member, etc.) in the developing device. The prior art for suppressing the occurrence of image defects is shown (Patent Documents 1 to 7).

  Patent Document 1 discloses an image including a printing rate calculation unit, a collection amount determination unit, and an operation control unit for the purpose of providing an image forming apparatus capable of selectively removing deteriorated toner according to the degree of toner deterioration. A forming apparatus has been proposed.

  The printing rate calculation unit calculates the printing rate AN of the image data. The recovery amount determination unit determines the recovery amount a of toner in the developing device 13 according to the printing rate AN calculated by the printing rate calculation unit. The operation control unit controls the developing device so that toner is supplied from the inside of the developing device onto the photosensitive drum based on the collected amount a determined by the collected amount determining unit. The image printing ratio (printing rate) is calculated by the ratio of the printing area per page of the sheet material to which the toner image is transferred.

  Patent Document 2 discloses an image forming apparatus capable of notifying a user at an appropriate timing before a consumable part (unit) becomes unusable. The image forming apparatus includes a unit that can be attached to and detached from the apparatus main body, and a storage medium that stores a plurality of near-end information for informing beforehand of a use limit defined by the unit.

  In addition, an operation unit capable of selecting one of the plurality of stored near-end information, and a calculation unit that compares and calculates real information representing the actual usage status of the unit and the selected near-end information are provided. Furthermore, a display unit is provided for displaying a message indicating that the unit usage limit is approaching when the actual usage status of the unit reaches a predetermined stage represented by near-end information based on the comparison calculation result. .

In Patent Document 3, it is possible to always discharge a constant toner without being influenced by a change in a printing rate or a temperature without complicating a developing device, and to maintain a stable image without a density change over a long period of time. An image forming method and an image forming apparatus are disclosed.

  Then, when the integrated value of the toner replenishment motor driving time per fixed time is less than a certain amount, it is judged that the deteriorated toner is increasing in the developing device, and the toner is forcibly discharged when not developing. Has been.

  Patent Document 4 discloses a technique for realizing a toner refresh operation that suppresses wasteful consumption of developer. Specifically, a step of forming a measurement patch image at a predetermined timing and a step of measuring the image density of the measurement patch image are disclosed.

  Also disclosed is a step of comparing the image density with a reference patch image density that is an image density of a measurement patch image having acceptable quality formed under predetermined image generation conditions. Further, a process is proposed in which a measurement patch image is formed under the image generation conditions in the formation of the reference patch image, and if the comparison result shows that the image density is equal to or lower than the reference image density, a forced developer consumption operation is executed. Has been.

  Patent Document 5 discloses an image forming apparatus capable of determining with high accuracy that the chargeability of toner has deteriorated.

  In this image forming apparatus, first, the photosensitive layer of the photosensitive drum is charged, the surface of the photosensitive layer is exposed at a specified density, a developing bias is applied to the developing roller, and the absolute value of the detection voltage Va is obtained from the developing current sensor. To do.

  A technique for determining whether or not the chargeability of the toner has deteriorated by determining whether or not the absolute value of the acquired detection voltage Va is less than a first threshold value preset in the ROM. Proposed.

  Patent Document 6 discloses a technique for solving the problem based on the premise that toner deterioration countermeasures that forcibly discharge toner based on the printing rate are insufficient to prevent image quality deterioration due to toner deterioration. Is disclosed. A technique for detecting the toner charge amount and controlling the forced discharge of the toner based on the detected toner charge amount has been proposed.

  Patent Document 7 discloses a technique that can prevent image formation and damage to an image forming apparatus when incompatible toner (deteriorated toner) is used with a simple configuration.

  Specifically, a developing cartridge including a developing roller carrying toner is detachably attached to the apparatus main body, and the CPU detects a driving current as a load applied to a motor that drives the developing roller. Then, a technique for comparing the detected drive current value M with a preset reference current value X to determine the suitability of toner has been proposed.

  As a result, even if the user accidentally uses non-conforming toner, the CPU can immediately determine it. Therefore, with a simple configuration, image formation by non-conforming toner and damage to the color laser printer can be prevented. Can be prevented.

  As concerned in the conventional example described above, when the image printing rate is low, the toner is significantly deteriorated in the developing chamber in which the toner is accommodated. As a result, the toner is fused to the developer carrying member and the developer layer thickness regulating member, and image defects are likely to occur.

On the other hand, the configuration according to the above conventional example has a detecting unit that detects deteriorated toner or toner that is incompatible with the developing device, and if these toners are detected, the user may be warned that the developing device is defective. Warn to recommend replacement of the developing device.

Further, when the developing device includes a new toner replenishing unit, when the deteriorated toner is detected, the deteriorated toner is discharged from the developing chamber, and new toner is replenished from the toner storage chamber to the developing chamber. A configuration for suppressing defects is also proposed.
JP 2007-233300 A JP 2007-187895 A JP-A-2005-55842 JP 2007-147782 A JP 2007-94282 A JP 2006-243114 A JP 2004-12661 A

  However, in the invention according to the conventional example, it is difficult to accurately detect the deteriorated toner. The reason will be described below.

  For example, Patent Document 1 proposes detecting deteriorated toner from the printing rate, Patent Document 2 from the number of printed sheets / number of printed pixels / developing cartridge drive amount, and Patent Document 3 from the supply roller drive time.

  These are inventions based on the premise that the toner deteriorates when a constant amount of toner is continuously coated on the developer carrying member for a long period of time. Note that “continuation of toner coating on the developer carrying member over a long period of time” corresponds to, for example, a case where the average value of the printing rate is low.

  That is, when the average value of the printing rate is low, the toner is consumed little by little from the developing chamber in which the toner is accommodated, so that the toner is continuously coated on the developer carrier for a long period of time, and deteriorated toner is generated. Will do.

  Therefore, Patent Documents 1 to 3 disclose techniques for setting various parameter ranges within a range in which deteriorated toner is hardly generated.

  However, the generation of the deteriorated toner is also caused by conditions other than the toner being continuously coated on the developer carrier over a long period of time. For example, the history of the developing device from the start of production until the start of use, the performance error and setting error of various members in the developing device such as the developer carrier and the developer layer thickness regulating member, the developing device such as temperature and humidity It is also affected by the usage environment.

  Therefore, in order to determine the threshold values of various parameters described in Patent Documents 1 to 3 within a range in which deteriorated toner is generated but not fused, a margin area is set in consideration of various factors. It must be established and decided.

  Therefore, in the margin area provided in the inventions described in Patent Document 1 to Patent Document 3, it may be determined that the deteriorated toner is detected even when the deteriorated toner is not actually generated. Therefore, there is a situation in which the developing device has to be replaced with a new one although no deteriorated toner is generated.

Further, when the developing device has a new toner replenishing mechanism, the toner is discharged from the developing chamber and the new toner is discharged from the toner containing chamber to the developing chamber even when no deteriorated toner is actually generated. A situation of replenishment can be considered.

  As described above, when the deteriorated toner cannot be detected with high accuracy, there is a possibility that a developing device and a developer that can form an image in a good state are wasted.

  Next, a method for detecting deteriorated toner in the inventions described in Patent Documents 4 to 6 will be described.

  Patent Document 4 discloses a technique for detecting deteriorated toner from patch density, Patent Document 5 from developing current, and Patent Document 6 from toner charge amount.

  That is, the technique disclosed in Patent Document 4 detects the deteriorated toner by paying attention to the fact that when an image is formed using deteriorated toner, the density of the formed image is changed as compared with normal toner. Further, the techniques disclosed in Patent Document 5 and Patent Document 6 detect the deteriorated toner by paying attention to the fact that the deteriorated toner changes its charged state as compared with the normal toner.

  However, each parameter used in the inventions described in Patent Documents 4 to 6 is a developing device such as a performance error or a setting error, a temperature or a humidity of various members in the developing device such as a developer carrier or a developer layer thickness regulating member. It is greatly affected by the usage environment. As a result, even though each parameter has changed due to factors other than the occurrence of deteriorated toner, it may be detected as the occurrence of deteriorated toner.

  Patent Document 7 discloses a technique for detecting deteriorated toner from an absolute value of a driving current of a motor that drives a developer carrier (hereinafter referred to as a developer carrier driving current). However, the absolute value of the developer carrier driving current is also influenced by factors other than the presence or absence of generation of deteriorated toner.

  First, the toner is attached to the seal member as a first factor. Usually, in order to prevent the developer from leaking from the developing device, a seal member is disposed at the position of the longitudinal end of the developer carrier. The toner adheres to a part of the seal member from the inside of the developing device, but the developer carrier driving current changes depending on the amount and position of the toner.

  A second factor is the amount of toner in the developing device. When the motor that drives the developer carrying member also drives the stirring member in the developing device, the developer carrying member driving current changes depending on the amount of toner in the developing device.

  Further, when a plurality of rotating bodies are driven by one motor, it is also affected by a change in driving current of a developer carrier other than the measurement target. For example, consider a case where four motors Y, M, C, and K are driven by one motor.

  When it is desired to detect the deteriorated toner of the developing device Y, the measurement error of the developer carrier driving current becomes large due to the influence of the change of the developer carrier driving current of the other developing devices M, C, and K. Further, even when the developer carrier driving current exceeds a predetermined threshold, it is difficult to determine in which developing unit the deteriorated toner is generated.

  Therefore, Patent Document 7 discloses a technique for detecting the presence or absence of the occurrence of deteriorated toner from the absolute value of the drive current of the motor that drives the developer carrier, but the absolute value of the developer carrier drive current is disclosed. Therefore, it is difficult to accurately detect the occurrence of deteriorated toner.

  SUMMARY OF THE INVENTION In view of the above situation, the present invention has an object to accurately detect deteriorated toner, suppress the occurrence of image defects, and prevent wasteful disposal of a developing device and toner capable of forming an image in a good state. And

In order to solve the above problems, in the present invention,
An image carrier carrying an electrostatic latent image on the surface;
A developing device for containing the one-component developer and supplying the one-component developer to the image carrier to develop the electrostatic latent image;
A developer carrying member provided in the developing device and carrying a one-component developer on the surface;
Drive means for driving at least one of the image carrier and the developer carrier;
In an image forming apparatus comprising:
The image carrier and the developer carrier are configured to be contactable and separable,
Driving load measuring means for measuring the driving load of the driving means when the image carrier and the developer carrier are in contact with each other and when they are apart from each other;
Developer deterioration determining means for determining deterioration of the developer stored in the developing device based on a measurement value by the driving load measuring means;
Further comprising a,
The developer deterioration determining means is
The driving load of the driving means measured by the driving load measuring means when the image carrier and the developer carrier are in contact with each other is separated from the image carrier and the developer carrier. When the absolute value of the difference between the driving load of the driving unit at the time is less than a predetermined threshold, it is determined that the developer has not deteriorated,
When the absolute value of the difference is equal to or greater than a predetermined threshold value, it is determined that the developer has deteriorated .

Also,
An image carrier carrying an electrostatic latent image on the surface;
A developer storage chamber for storing a one-component developer;
A developing chamber in which the developer is replenished from the developer containing chamber;
A developer carrying member disposed in the developing chamber and carrying the developer on the surface;
Drive means for driving at least one of the image carrier and the developer carrier;
In an image forming apparatus comprising:
The image carrier and the developer carrier are configured to be contactable and separable,
Driving load measuring means for measuring the driving load of the driving means when the image carrier and the developer carrier are in contact with each other and when they are apart from each other;
A developer deterioration determining means for determining deterioration of the developer based on a measurement value by the driving load measuring means;
Developer supply means for supplying the developer from the developer storage chamber to the development chamber based on the determination by the developer deterioration determination means;
It is characterized by providing.

Also,
An image carrier carrying an electrostatic latent image on the surface;
A developer storage chamber for storing a one-component developer;
A developing chamber in which the developer is replenished from the developer containing chamber;
A developer carrying member disposed in the developing chamber and carrying the developer on the surface;
Drive means for driving at least one of the image carrier and the developer carrier;
In an image forming apparatus comprising:
The image carrier and the developer carrier are configured to be contactable and separable,
Driving load measuring means for measuring the driving load of the driving means when the image carrier and the developer carrier are in contact with each other and when they are apart from each other;
A developer deterioration determining means for determining deterioration of the developer based on a measurement value by the driving load measuring means;
A developer discharging means for discharging the developer from the developing chamber based on the determination by the developer deterioration determining means;
It is characterized by providing.

Also,
An image carrier carrying an electrostatic latent image on the surface;
A developing device containing a one-component developer to be supplied to the electrostatic latent image;
A developer carrying member provided in the developing device and carrying a one-component developer on the surface;
Drive means for driving at least one of the image carrier and the developer carrier;
In an image forming apparatus comprising:
The image carrier and the developer carrier are configured to be contactable and separable,
Driving load measuring means for measuring the driving load of the driving means when the image carrier and the developer carrier are in contact with each other and when they are apart from each other;
A developer deterioration determining means for determining deterioration of the developer based on a measurement value by the driving load measuring means;
An image forming condition control means for controlling an image forming condition based on the determination by the developer deterioration determining means;
It is characterized by providing.

  According to the present invention, it is possible to accurately detect deteriorated toner, suppress the occurrence of image defects, and prevent wasteful disposal of developing devices and toner that can form images in a good state.

  The best mode for carrying out the present invention will be exemplarily described in detail below based on the embodiments with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in this embodiment are not intended to limit the scope of the present invention only to those unless otherwise specified. Absent.

[First Embodiment]
An image forming apparatus according to the first embodiment of the present invention will be described with reference to FIGS. The following are (the overall configuration of the image forming apparatus), (the configuration of the developing apparatus), (one-component developer), (the principle of the toner deterioration detection method), (the toner deterioration detection method), and the durability test under actual use conditions. ), (Sequence control under actual use conditions), and (Supplementary explanation).

(Overall configuration of image forming apparatus)
FIG. 3 is a schematic configuration diagram of the image forming apparatus 100 according to the present embodiment. In this embodiment, the image forming apparatus 100 is described using an electrophotographic laser beam printer.

  The image forming apparatus 100 includes a photosensitive drum 1 as a rotatable drum-type image carrier. Around the photosensitive drum 1, a charging roller (charging device) 2 as a charging unit, a developing device 3 as a developing unit, a transfer roller (transfer device) 4 as a transferring unit, a cleaning blade 5 as a cleaning member, and the like are installed. Has been.

  The cleaning blade 5 is attached to the waste toner storage container 13, and the cleaning blade 5 and the waste toner storage container 13 constitute a cleaner (cleaning device) 21 as cleaning means.

  In this embodiment, the photosensitive drum 1, the charging roller 2, the developing device 3, and the cleaner 21 are integrally formed into a cartridge, and a process cartridge 19 that is detachable from the image forming apparatus main body 100 is configured. Has been.

  A gap between the charging roller 2 and the developing device 3 is emitted from an exposure device (electrostatic latent image forming device) 6 serving as an exposure device (electrostatic latent image forming device) disposed outside the process cartridge 19. This is the optical path of the laser beam L.

  Further, a fixing device 7 as a fixing unit is disposed on the downstream side in the conveyance direction of the recording material P from the transfer portion (transfer nip) N between the photosensitive drum 1 and the transfer roller 4.

  The photosensitive drum 1 in the present embodiment is a negatively charged organic photoreceptor having a diameter of 30 mm, and has a photoreceptor layer on an aluminum drum base. The photosensitive drum 1 is rotationally driven at a predetermined peripheral speed in the arrow direction (clockwise direction) shown in FIG. 3 and is uniformly charged to a negative polarity by the charging roller 2 during the rotation process. The surface moving speed (peripheral speed) of the photosensitive drum 1 is preferably 50 mm / s or more and 600 mm / s or less.

  The charging roller 2 is rotatable and is disposed in contact with the surface of the photosensitive drum 1. The charging roller 2 uniformly charges the surface of the photosensitive drum 1 to a predetermined negative potential with a charging bias applied from a charging bias power source (not shown).

  The developing device 3 uses a non-magnetic one-component developer as a developer, that is, a non-magnetic toner T, and develops and visualizes an electrostatic latent image carried on the surface of the photosensitive drum 1 as a toner image and visualizes it. Device. In the present embodiment, the regular charging polarity of the toner T is negative.

  The transfer roller 4 contacts the photosensitive drum 1 with a predetermined pressing force to form a transfer portion (transfer nip) N. A transfer bias is applied to the transfer roller 4 from a transfer bias power source (not shown). As a result, in this embodiment, a positive charge is applied to the recording material P from the transfer roller 4, and the negative polarity on the photosensitive drum 1 is applied to the recording material P in contact with the photosensitive drum 1 by the electric field due to this charge. The toner T is transferred.

  Examples of the material of the cleaning blade 5 include those having rubber elasticity such as silicone rubber, nitrile rubber, and chloroprene rubber, and polyurethane rubber is preferable from the viewpoint of wear resistance, permanent deformation, and the like.

  The tip of the cleaning blade 5 on the free end side is in contact with the surface of the photosensitive drum 1 with a predetermined pressure in a so-called counter direction with respect to the rotation direction of the photosensitive drum 1. That is, the cleaning blade 5 is attached to the waste toner storage container 13 with the free end on the upstream side facing the rotation direction of the photosensitive drum 1.

  A fine powder as a lubricant is applied to the tip of the cleaning blade 5 in advance for the purpose of reducing the frictional force with the surface of the rotating photosensitive drum 1.

  Note that various materials and shapes have been proposed as fine powders to be applied to the tip of the cleaning blade 5. In the present embodiment, the following is used as the lubricant applied in advance to the tip portion of the cleaning blade 5.

  This is a mixture of spherical silicone resin particles having an average particle size of 3 μm and circularity of 0.93 and fluorinated graphite having an average particle size of 2 μm having an irregular shape (specifically, a scale shape) at a predetermined ratio. is there. Here, the product name Tospearl (made by Toshiba Silicone Co., Ltd.) is used for the silicone resin particles having a circularity of 0.93, and the product name Cefbon (made by Central Glass Co., Ltd.) is used for the fluorinated graphite having an average particle size of 2 μm. Using.

  The circularity can be measured using, for example, a flow type particle image analyzer FPIA-1000 manufactured by Toa Medical Electronics Co., Ltd. As a method for applying the fine powder, a method in which a single substance is dispersed in a volatile liquid such as alcohol and this solution is applied to the tip of the cleaning blade 5 is used.

  The coating width from the edge tip of the cleaning blade 5 was approximately 1 mm. The cleaning blade 5 removes toner remaining on the surface of the photosensitive drum 1 after transfer (transfer residual toner (transfer residual developer)) from the surface of the photosensitive drum 1.

  The exposure device 6 includes a laser driver, a laser diode, a polygon mirror 14 and the like. Laser light L modulated in accordance with the time-series electrical digital image signal of the image information input to the laser driver is output from the laser diode.

  The surface of the photosensitive drum 1 is exposed by the laser light L scanned through the optical lens system 15 by the polygon mirror 14 that rotates at high speed. Thereby, an electrostatic latent image corresponding to the image information is formed on the surface of the photosensitive drum 1.

  The fixing device 7 includes a rotatable fixing roller 7a and a pressure roller 7b. The fixing device 7 heats and pressurizes the toner image transferred to the surface of the recording material P while nipping and conveying the recording material P at the fixing nip between the fixing roller 7a and the pressure roller 7b. As a result, the toner image on the recording material P is fixed to the recording material P.

  At the time of image formation (operation), the photosensitive drum 1 is rotationally driven at a peripheral speed of 200 mm / s in the direction of the arrow shown in FIG. 3 by a driving means (not shown). The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 to which a charging bias (for example, a DC voltage of −1000 V) is applied.

  The surface of the charged photosensitive drum 1 is exposed by a laser beam L corresponding to image information by an exposure device 6. As a result, an electrostatic latent image corresponding to the image information input to the image forming apparatus 100 is formed on the photosensitive drum 1 (on the image carrier). At this time, the laser power of the exposure device 6 is adjusted so that the dark portion potential of the unexposed portion on the photosensitive drum 1 is −500 V, and the bright portion potential of the exposed portion is −100 V.

  The electrostatic latent image on the photosensitive drum 1 is visualized as a toner image by the developing device 3. In the present embodiment, a developing bias having the same polarity as the charging polarity (negative polarity in the present embodiment) of the photosensitive drum 1 is applied to the developing roller 9 as a developer carrying member provided in the developing device 3. Further, the developing roller 9 in the present embodiment is provided so as to be able to contact and separate from the photosensitive drum 1 by a separation mechanism (not shown), and is rotationally driven by a driving means (not shown).

  As a result, the toner T charged to the same polarity as the charging polarity of the photosensitive drum 1 (negative polarity in this embodiment) is transferred from the developing roller 9 to the bright portion potential portion of the electrostatic latent image on the photosensitive drum 1. Adhere. Thus, the electrostatic latent image on the photosensitive drum 1 is reversely developed. Details of the developing device 3 and the toner T will be described later.

  When the toner image on the photosensitive drum 1 reaches the transfer nip N between the photosensitive drum 1 and the transfer roller 4, the recording material P such as recording paper is conveyed to the transfer nip N via the conveyance path 22 in accordance with this timing. Is done. The recording material P is fed one by one from a cassette or the like as a recording material storage unit by the pickup roller 16 and is conveyed by a registration roller (not shown) or the like.

The toner image on the photosensitive drum 1 is transferred to the recording material P by the transfer roller 4 to which a transfer bias having a polarity opposite to that of the toner T (positive polarity in the present embodiment) is applied.

  The recording material P onto which the toner image has been transferred is conveyed to the fixing device 7 and heated and pressed at the fixing nip between the fixing roller 7a and the pressure roller 7b. As a result, the toner image is thermally fixed on the recording material P. Thereafter, the recording material P is discharged onto the discharge tray 17.

  Further, the transfer residual toner remaining on the surface of the photosensitive drum 1 after the toner image transfer process is removed by the cleaning blade 5 and collected in the waste toner storage container 13.

(Configuration of developing device)
With reference to FIG. 2, the structure of the developing device according to the present embodiment will be described. FIG. 2 is a schematic configuration diagram of the developing device in the present embodiment.

The developing device 3 in the present embodiment is a contact one-component developing device that performs development by a non-magnetic one-component DC contact developing method. The developing device 3 of such a developing system includes a developing roller having a semiconductive property (medium resistance: for example, a volume resistivity of 10 ⁹ to 10 ¹¹ Ω · cm) as a developer carrier, or a developing roller having a dielectric layer formed on the surface. It is used to develop it by pressing it against the surface layer of the photosensitive drum 1.

  The developing device 3 is a contact one-component developing device that performs development with a non-magnetic toner T as a one-component developer. The developing device 3 includes a developing roller 9 as a developer carrying member, an elastic roller 10 as a developer supply member, a regulating blade 11 as a layer thickness regulating member, and a stirring member 12.

  Here, the developing roller 9 is disposed opposite to the photosensitive drum 1 at the opening of the developing container 8 and is rotatably provided in the direction of the arrow (counterclockwise) shown in FIG. The elastic roller 10 is rotatable and is provided so as to be in pressure contact with the developing roller 9.

  The regulating blade 11 has elasticity and is provided so as to contact the developing roller 9. The stirring member 12 is rotatably provided so as to stir the toner T in the developing container 8. The regulating blade 11 is in contact with the developing roller 9 on the downstream side in the rotation direction of the developing roller 9 with respect to the pressure contact portion between the developing roller 9 and the elastic roller 10.

  The toner T agitated by the agitating member 12 is supplied to the surface of the developing roller 9 by an elastic roller 10 that rotates in pressure contact with the developing roller 9. The toner T supplied to the surface of the developing roller 9 is conveyed along with the rotation of the developing roller 9, and is charged by friction at the contact portion between the regulating blade 11 and the developing roller 9, so that the surface of the developing roller 9 is thinned. Is done.

  The thinned toner T is carried and conveyed by the rotation of the developing roller 9 and adheres to the electrostatic latent image formed on the photosensitive drum 1 at a contact portion (developing portion) with the photosensitive drum 1 to be a visible image. Turn into. The toner T that has not contributed to the development on the developing roller 9 is peeled off by the elastic roller 10.

  More specifically, the developing roller 9 is located at an opening extending in the longitudinal direction of the developing container 8 containing the toner T, and is disposed to face the photosensitive drum 1. The developing roller 9 is in contact with the photosensitive drum 1 with a predetermined contact width, and has a peripheral speed (300 mm / sec) higher than the peripheral speed (200 mm / s) of the photosensitive drum 1 in the direction of the arrow (reverse direction) shown in FIG. It is rotated clockwise. In the present embodiment, the photosensitive drum 1 and the developing roller 9 rotate so that the surface movement directions thereof are the same at the contact portion.

  Next, details of a method of driving the developing roller 9 will be described.

  In the present embodiment, a motor (not shown) is used as a driving unit for the developing roller 9. In addition, the developing roller 9, the elastic roller 10, and the stirring member 12 in the developing device were also rotationally driven by this motor. However, for the driving of the photosensitive drum 1, a rotational driving means different from the motor for driving the developing roller 9 is used.

  The load when driving the developing device 3 is mainly the load between the developing roller 9 and the regulating blade 11, the load between the developing roller 9 and the elastic roller 10, the load between the developing roller 9 and the photosensitive drum 1, and the developing roller. 9 and the seal member 23, and the rotational load of the stirring member 12 in the developing container. Further, since the toner always exists between the members, the load varies depending on the state of the toner.

  As will be described later, the toner deterioration detection in the present embodiment is to detect toner deterioration based on the rotational load of the developing roller 9. In particular, in Comparative Example 2, Comparative Example 3, and the present embodiment to the fifth embodiment, a load for rotationally driving the developing roller 9 is detected by electric power.

  The surface of the developing roller 9 has moderate unevenness in order to increase the friction probability with the toner T and to carry the toner T satisfactorily. In the present embodiment, the developing roller 9 has a diameter of 16 mm and a length of 240 mm, and is formed by coating an acrylic / urethane thin layer on a 4 mm thick silicone rubber layer provided on a cored bar. Has been.

  The developing roller 9 is connected to a developing bias power source as a first voltage applying unit. In this embodiment, a developing bias having a predetermined negative potential is applied to the developing roller 9 from the developing bias power source.

The developing roller 9 has an electrical resistance value of 10 ⁴ to 10 ⁶ Ω, surface roughness [arithmetic average roughness: JIS centerline average roughness (JIS B 0601: 2001)] Ra of 0.3 to 5.0 μm, It is preferable that the hardness is adjusted to 40 ° to 70 ° C. (weight 1 kg) as Asker C hardness.

In the present embodiment, the developing roller 9 having an electric resistance of 10 ⁵ Ω, a surface roughness Ra of 2.0 μm, and an Asker C hardness of 55 ° is used.

  The electrical resistance value of the developing roller 9 is measured as follows. An aluminum roller (not shown) having a diameter of 30 mm and the developing roller 9 are brought into contact with each other in the entire longitudinal direction with a contact load of 500 gf (4.9 N), and the aluminum roller is rotated at 0.5 rps.

  Then, a DC voltage of −400 V is applied to the developing roller 9 and a 10 kΩ resistor is disposed on the ground side. Then, the voltage across the resistor is measured, and the current value is calculated from the measured voltage value to calculate the resistance value of the developing roller 9.

  Further, a flexible seal member 23 is provided on the downstream side in the rotation direction of the developing roller 9 with respect to the contact portion (developing portion) between the developing roller 9 and the photosensitive drum 1. The seal member 23 allows the undeveloped toner T to pass into the developing container 8, and the toner T in the developing container 8 rotates the developing roller 9 more than the contact portion between the developing roller 9 and the photosensitive drum 1. Prevent leakage from the downstream side.

  The elastic roller 10 abuts on the developing roller 9 on the upstream side of the abutting portion between the regulating blade 11 and the developing roller 9 in the rotational direction of the developing roller 9, and is rotationally driven in the direction of the arrow (counterclockwise) shown in FIG. The

The elastic roller 10 preferably has a foamed skeleton-like sponge structure in terms of the supply performance of the toner T to the developing roller 9 and the stripping performance of the undeveloped toner T from the developing roller 9. In the present embodiment, the elastic roller 10 having a diameter of 16 mm in which a polyurethane foam (a sponge made of polyurethane) is provided on the core metal is used.

  The contact width of the elastic roller 10 with respect to the developing roller 9 is preferably 1 to 6 mm. The elastic roller 10 preferably has a relative speed with respect to the developing roller 9 at the contact portion with the developing roller 9. In this embodiment, the contact width with the developing roller 9 is set to 2 mm. The contact pressure (linear pressure) between the elastic roller 10 and the developing roller 9 at this time was 40 gf / cm (0.392 N / cm).

  In the present embodiment, the elastic roller 10 is rotationally driven at a predetermined timing by a driving means (not shown) so that the peripheral speed becomes 200 mm / sec during the developing operation. The elastic roller 10 and the developing roller 9 rotate so that their surface movement directions are opposite to each other at the contact position. The potential of the elastic roller 10 and the potential of the developing roller 9 are equipotential.

  The regulating blade 11 has elasticity, and the vicinity of the free end side of the developing roller 9 on the downstream side in the rotation direction of the developing roller 9 with respect to the contact portion between the developing roller 9 and the elastic roller 10 is the outer peripheral surface of the developing roller 9. It is provided so as to come into contact with surface contact.

  The regulation blade 11 is preferably made of a thin metal plate of SUS or phosphor bronze having conductivity and spring elasticity. A conductive rubber material or the like may be bonded to the contact surface side with the developing roller 9 using a rubber material such as silicone or urethane or a metal thin plate of SUS or phosphor bronze having spring elasticity as a base.

  In the present embodiment, the regulation blade 11 formed of a plate-like phosphor bronze metal thin plate having a thickness of 0.1 mm is used. Further, the contact pressure (linear pressure) of the regulating blade 11 with respect to the developing roller 9 is set to 25 gf / cm (0.245 N / cm) or more and 35 gf / cm (0.343 N / cm) or less in this embodiment. .

  The contact direction of the regulating blade 11 with respect to the developing roller 9 is a so-called counter direction in which the free end of the regulating blade 11 is positioned upstream of the contacting portion with the developing roller 9 in the rotation direction of the developing roller 9. It has become.

  In the present embodiment, the linear pressure is measured as follows. That is, the linear pressure was converted from the value when three thin metal plates having a known friction coefficient were inserted into the abutting portion, and the central one was pulled out by a spring gauge.

Moreover, an electric field can be formed in the regulating blade nip by applying a voltage to the regulating blade 11. Here, the voltage applied to the regulating blade 11 is Vb, the voltage applied to the developing roller 9 is Vdev, and ΔVb is defined as follows.
Definition formula: ΔVb = Vb−Vdev

  According to this definition, for example, when ΔVb is positive, an electric field that attracts negatively charged toner toward the regulating blade 11 is formed in the regulating blade nip.

  On the other hand, when ΔVb is negative, an electric field that attracts negatively charged toner toward the developing roller 9 is formed in the regulating blade nip. In the present embodiment, ΔVb = −200V is set.

During the developing operation, the toner T in the developing container 8 is sent to the elastic roller 10 side as the stirring member 12 rotates in the direction of the arrow (clockwise) shown in FIG. The toner T is conveyed to the vicinity of the developing roller 9 by the rotation of the elastic roller 10 in the direction of the arrow (counterclockwise) shown in FIG. The toner T carried on the elastic roller 10 is frictionally charged by being rubbed against the developing roller 9 at the contact portion between the developing roller 9 and the elastic roller 10 and adheres to the developing roller 9.

  Then, as the developing roller 9 rotates in the direction of the arrow (counterclockwise) shown in FIG. 2, the toner T is sent under pressure contact with the regulating blade 11, and is thinned on the developing roller 9. It is conveyed to the developing unit which is the opposite unit. In the present embodiment, the good charge amount of the toner T is set to be −40 to −70 mC / kg.

  The toner T formed in a thin layer on the developing roller 9 (on the developer carrying member) is statically formed on the photosensitive drum 1 in the developing portion when a developing bias of −300 V is applied to the developing roller 9. Adhere to the electrostatic latent image. As a result, the electrostatic latent image on the photosensitive drum 1 is developed as a toner image.

  The toner T that has not contributed to the development on the developing roller 9 is peeled off from the surface of the developing roller 9 at the contact portion with the elastic roller 10. Most of the toner T thus peeled off is conveyed as the elastic roller 10 rotates, and is mixed with the toner T in the developing container 8 so that the charged charge of the toner T is dispersed. At the same time, new toner T is supplied onto the developing roller 9 by the rotation of the elastic roller 10, and the above-described developing operation is repeated.

(Explanation about one-component developer)
Next, the toner T as a one-component developer used in the present embodiment will be described.

  In the present embodiment, a toner having a volume average particle diameter of 4.0 μm or more and 10.0 μm or less and an average circularity of 0.950 or more is used.

  When the volume average particle size of the toner of the present embodiment is less than 4 μm, the chargeability due to the deterioration of the fluidity of the toner particles tends to be non-uniform, for example, image fogging occurs in a high humidity environment. There is concern that it will be easier. Further, when the volume average particle diameter of the toner exceeds 10 μm, high-definition output becomes difficult, and there is a concern that the required image quality cannot be satisfied.

  For example, a Coulter Counter TA-II type or Coulter Multisizer II (manufactured by Beckman Coulter, Inc.) is used for measuring the volume average particle diameter of the toner T. The volume average particle diameter of the toner T can be measured with a measuring device in which an interface (manufactured by Nikka Ki Bios Co., Ltd.) for outputting the number distribution and volume distribution and a personal computer are connected. In this measurement, an electrolytic solution is used. For this electrolytic solution, for example, a 1% NaCl aqueous solution prepared using primary sodium chloride or ISOTON R-II (manufactured by Coulter Scientific Japan Co., Ltd.) can be used. .

  As a measuring method, 0.1 to 5 ml of a surfactant (preferably alkylbenzene sulfonate) is added as a dispersant to 100 to 150 ml of the aqueous electrolytic solution, and 2 to 20 mg of a measurement sample is further added. The electrolytic solution in which the sample is suspended is dispersed for about 1 minute with an ultrasonic disperser, and the volume distribution is determined by measuring the volume of toner of 2 μm or more with the Coulter Counter TA-II type using an aperture of 100 μm as an aperture. calculate. Then, the volume average particle diameter obtained from the volume distribution of the present embodiment is obtained.

The shape control of the toner according to the present embodiment is such that the average circularity of the toner in the equivalent diameter-circularity scattergram based on the number of toners measured by the flow type particle image measuring device is 0.9.
A range of 50 or more is preferred.

  A toner having an average circularity of less than 0.950 means a toner whose shape has moved away from a spherical shape and has approached an indeterminate shape. Such irregular shaped toner tends to be crushed in the developing device during development, so that the particle size distribution fluctuates or the charge amount distribution becomes broad. This is not preferable because an undesired phenomenon such as an increase tends to occur.

The circularity of the toner T in the present embodiment is used as a simple method for quantitatively expressing the shape of the toner particles. In the present embodiment, measurement was performed using a flow type particle image measurement device FPIA-1000 (manufactured by Toa Medical Electronics (currently Sysmex) Co., Ltd.), and the calculation was performed using the following formula. The measurement conditions were such that the toner particle concentration at the time of measurement was adjusted to 5000 to 15000 particles / μl, and 1000 or more toner particles were measured.
Definition formula: Circularity = (perimeter of a circle having the same area as the particle projection area) / (perimeter of the particle projection image)

  In the above formula, the “particle projected area” is the area of the binarized toner particle image, and the “peripheral length of the particle projected image” is the contour line obtained by connecting the edge points of the toner particle image. Is defined as the length of

  As a specific measurement method, 10 ml of ion-exchanged water from which impure solids and the like are previously removed is prepared in a container, and a surfactant, preferably an alkylbenzene sulfonate, is added as a dispersant therein, and then further measurement is performed. Add about 0.02 g of sample and disperse uniformly.

  As a means to disperse, an ultrasonic disperser UH-50 type (manufactured by SMT Co., Ltd.) equipped with a titanium alloy tip of φ5 mm as a vibrator is used. A dispersion is obtained.

  As means for achieving the volume average particle diameter and average circularity of the present embodiment within the preferred ranges of the present invention, in addition to the production method by the so-called pulverization method, toner is produced using the following method, etc. It is also possible to do. That is, a method of directly producing toner using the suspension polymerization method disclosed in JP-A-36-10231 and JP-A-59-53856, or a heavy polymer that is soluble in a monomer. This is a dispersion polymerization method in which a toner is directly produced using a water-based organic solvent in which the coalescence is insoluble. Further, it is an emulsion polymerization method represented by a soap-free polymerization method in which a toner is produced by direct polymerization in the presence of a water-soluble polar polymerization initiator.

  In this embodiment, the shape of the toner can be easily controlled, and a suspension under normal pressure or under pressure where a fine particle toner having a sharp particle size distribution and a volume average particle size of 4 to 10 μm can be obtained relatively easily. A polymerization method was used. Then, styrene and n-butyl acrylate as monomers, a salicylic acid metal compound as a charge control agent, a saturated polyester as a polar resin, and a wax and a colorant were added to produce colored suspended particles. The toner particles have a volume average particle diameter of 6.5 μm and an average circularity of 0.980.

  Next, the external additive attached to the developer base particles (hereinafter, toner base particles), which is a feature of the present embodiment, will be described below.

In the present embodiment, silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are 1.0 part by mass or more and 3.0 parts by mass with respect to 100 parts by mass of toner base particles (100 parts by mass of developer base particles). Less than externally added. Further, fine particles other than silica having an average primary particle size of 5 nm or more and less than 500 nm are externally added in an amount of less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles.

  If silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are not externally added, there is a concern that good toner fluidity cannot be obtained, and it becomes difficult to sufficiently charge the toner particles. Is done. If good toner fluidity cannot be obtained, and toner particles are not sufficiently charged, there is a concern that problems such as increased fog, decreased image density, and toner scattering are likely to occur. .

  In the case where silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to less than 1.0 part by mass with respect to 100 parts by mass of the toner base particles, There is a concern that good toner fluidity cannot be obtained in the latter half of use.

  In such a case, there is a concern that it is difficult to sufficiently charge the toner particles. If the toner particles are not sufficiently charged, problems such as an increase in fog, a decrease in image density, and toner scattering are likely to occur.

  In addition, when silica fine particles having an average primary particle size of 5 nm or more and less than 100 nm are externally added to 100 parts by mass of the toner base particles, silica contamination on the surface of the photoreceptor or the developer carrying member is caused. There is a concern that it is likely to occur.

  When silica contamination occurs on the surface of the photosensitive member or the developer carrying member, it causes development problems due to fusion to the surface of the photosensitive member or contamination of the lower layer of the developer carrying member in continuous printing of images. There is concern.

  As described above, the silica fine particles having an average primary particle diameter of 5 nm or more and less than 100 nm are externally added to 1.0 part by mass or more and less than 3.0 parts by mass with respect to 100 parts by mass of the toner base particles. The fluidity of the toner can be obtained. Therefore, it is possible to sufficiently charge the toner particles.

  Here, in order to maintain the performance of each process of development, transfer, fixing, and cleaning, a small amount of other fine particles may be externally added to finely adjust the fluidity and chargeability of the toner.

  However, if the average primary particle size of the fine particles is 500 nm or more, it is easy to detach from the toner surface, and it becomes difficult to maintain the fluidity and chargeability of the toner for a long period of time, so the average primary particle size is 5 nm or more and less than 500 nm. It is preferable to externally add the fine particles.

  In addition, when fine particles having an average primary particle size of less than 5 nm are externally added, the fine particles have a high cohesive property and have a wide particle size distribution having a strong cohesive property that is difficult to break even by crushing treatment instead of the primary particles. It tends to behave as an aggregate. For this reason, there is a concern that image defects are likely to occur due to development of the aggregate, damage to the fixing member, the image carrier, or the developer carrier.

  Usually, the average primary particle size is 5 nm or more and less than 100 nm if fine particles having an average primary particle size of 5 nm or more and less than 500 nm are externally added to less than 0.5 parts by mass with respect to 100 parts by mass of the toner base particles. The effect of silica fine particles is great. Therefore, good toner fluidity and chargeability can be obtained. Thereby, a sufficiently good image can be output.

Examples of the fine particles having an average primary particle size of 5 nm or more and less than 500 nm include the following. For example, lubricant powders such as Teflon (registered trademark) powder, zinc stearate powder, and polyvinylidene fluoride powder. Furthermore, abrasives such as cerium oxide powder, silicon carbide powder, and strontium titanate powder may be used.

  In addition, fluidity-imparting agents such as titanium oxide powder and aluminum oxide powder, cleaning of anti-caking agents, spherical silica particles, spherical polymethylsilsesquioxane particles, spherical resin particles, and other inorganic or organic spherical particles. An auxiliary agent may be used. In addition, organic fine particles having opposite polarity and inorganic fine particles can be used in small amounts as a developability improver. These additives can also be used after hydrophobizing the surface.

  A method for measuring the average primary particle size of the external additive fine particles in the present embodiment will be described below.

  In the measurement, a photograph of the toner magnified with a scanning electron microscope is used, and a photograph of the toner mapped with the elements contained in the external additive fine particles is further contrasted by an elemental analysis means such as XMA attached to the scanning electron microscope. Done. Then, while contrasting these photographs, 100 or more primary particles of the external additive fine particles adhering to or liberating from the toner surface were measured, and the number average particle diameter was determined to obtain the average primary particle diameter. taking measurement.

  The silica fine particles are preferably hydrophobized. For example, the surface of silica fine particles can be hydrophobized by treating with silicone oil.

  Silica fine particles are generally added to improve the fluidity of the toner and make the toner base particles uniformly charged. By treating the inorganic fine particles with a silicone oil as in the present embodiment, the following treatment is performed. Such a function can be provided. The functions include not only adjustment of toner charge amount and environmental stability, but also improvement of releasability from the fixing belt of the present embodiment.

  It is more preferable that the silica fine particles are hydrophobized in order to keep the charge amount of the toner particles high even in a high-humidity environment and to prevent toner scattering.

  In the present embodiment, 1.5 parts by mass of silica A having an average primary particle diameter of 10 nm and 0.4 parts by mass of silica B having an average primary particle diameter of 50 nm are measured with respect to 100 parts by mass of toner base particles. And dry mixed. This also applies to second to fifth embodiments described later and comparative examples.

The toner volume resistance value of the toner T is 10 ¹⁴ Ω · cm or more. The measurement conditions of the volume resistance value of the toner T are: diameter φ: 6 mm, measurement electrode plate area: 0.283 cm ² , pressure: weight of 1500 g, pressure: 96.1 kPa, powder layer thickness at measurement: 0.00. It was 5-1.0 mm. Then, a 400 V DC voltage is measured with a microammeter (YHP (Yokogawa Hewlett-Packard Co., Ltd.) 4140 pA METER / DC VOLTAGE SOUCE), and a volume resistance value (specific resistance) is calculated from the measured current value. .

  In the present embodiment, the glass transition temperature (Tg) of the toner binder resin is preferably 40 to 70 ° C. When Tg is less than 40 ° C., problems are likely to occur from the viewpoint of storage stability and durability stability of the toner, and when it exceeds 70 ° C., the fixing point of the toner is increased.

  In the case of a color toner for forming a full-color image, the color mixing property at the time of fixing each color toner is lowered, the color reproducibility is slightly inferior, and the transparency of the OHP image is lowered. In particular, the temperature is preferably 45 to 65 ° C. In the present embodiment, toner having a Tg of 60 ° C. is used.

The maximum endothermic peak of the wax contained in the toner is preferably 45 to 75 ° C. When the maximum endothermic peak of the wax is lower than 45 ° C., it becomes lower than the glass transition temperature of the resin used in the present embodiment, so that it dissolves on the toner surface when left in a high temperature environment, so that the anti-blocking performance is greatly improved. There is concern about getting worse.

  On the other hand, if the maximum endothermic peak is greater than 75 ° C., the wax cannot quickly move to the surface of the molten toner during toner fixing and melting, and the releasability deteriorates, so that high temperature offset is likely to occur. In particular, the temperature is preferably 50 to 70 ° C. In this embodiment, toner having a maximum endothermic peak of 65 ° C. is used.

  In the present embodiment, Tg is measured according to ASTM D3418-82 using, for example, a differential scanning calorimeter “DSC-7” manufactured by PerkinElmer. The temperature correction of the device detection unit uses the melting points of indium and zinc, and the correction of heat uses the heat of fusion of indium. The measurement sample is precisely weighed in an amount of 2 to 10 mg, preferably 5 mg. As the measurement sample, an aluminum pan is used and an empty pan is set for control, and measurement is performed at room temperature and normal humidity at a temperature increase rate of 10 ° C./min within a measurement temperature range of 30 to 200 ° C. Analysis is performed with a DSC (Differential Scanning Calorimetry) curve in the temperature range of 30 to 200 ° C. obtained in the second temperature raising process.

  As for the glass transition temperature (Tg), a value obtained by analyzing by the midpoint method from the obtained DSC curve is used. For the melting point of the wax, the temperature value of the endothermic main peak of the obtained DSC curve is used.

(Principle of toner deterioration detection method)
The principle of the toner deterioration detection method in the present embodiment will be described.

  The detection of the driving power of the developing roller 9 is performed during non-image formation in which toner is not developed on the photosensitive drum 1. In this embodiment, the developing roller surface peripheral speed V1 rotates at 300 [mm / s], and the photosensitive drum surface peripheral speed V2 rotates at 200 [mm / s]. The rotation direction is the same in the developing unit, the peripheral speed difference V1-V2 is 100 [mm / s], and the developing roller 9 rotates faster.

  In the developing unit, the developing roller 9 and the photosensitive drum 1 are in contact via toner. During non-image formation, the surface potential of the photosensitive drum 1 is charged to about −500V, and a −300V voltage is applied to the core of the developing roller 9.

  Since the toner in the present embodiment is a negatively charged toner, the toner passes through the developing portion while adhering to the surface of the developing roller 9. That is, the peripheral speed difference of 100 [mm / s] occurs between the toner layer on the developing roller 9 and the surface of the photosensitive drum 1.

  FIG. 13 shows a balance of forces in the developing portion when the developing roller 9 and the photosensitive drum 1 are in contact with each other. FIG. 14 shows the balance of forces in the developing section when the developing roller 9 and the photosensitive drum 1 are separated from each other.

  In FIG. 13, the developing roller 9 and the photosensitive drum 1 are in contact with each other, and the vertical effect F <b> 2 is applied to the surface of the photosensitive drum 1 and the toner layer on the developing roller 9. A frictional force is generated between the toner layer on the developing roller 9 and the surface of the photosensitive drum 1. If the dynamic friction coefficient at this time is μ, the developing roller 9 receives a force μF2 in a direction that prevents rotation, and the photosensitive drum 1 receives a force μF2 in a direction that helps rotation.

  In contrast, in FIG. 14, the developing roller 9 and the photosensitive drum 1 are separated from each other, and no force acts between the toner layer on the developing roller 9 and the photosensitive drum 1.

  Accordingly, when the photosensitive drum 1 and the developing roller 9 are brought into contact with each other, compared to when the photosensitive drum 1 and the developing roller 9 are separated from each other, the developing roller 9 rubs against the photosensitive drum 1, thereby extra amount of μF 2 × 100 [mm / s] Drive power is required.

  The μF2 × 100 [mm / s] is the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are in contact, and the developing roller driving when the developing roller 9 and the photosensitive drum 1 are separated from each other. It is almost the same as the difference from electric power.

  Here, the inventor of the present invention has found that when toner fusing occurs on the developing roller 9 and the regulating blade 11, the difference increases compared to the initial use of the apparatus main body.

  This means that even if the developing device 3 is continuously used, F2 does not change, so that the dynamic friction coefficient μ between the toner layer on the developing roller 9 and the surface of the photosensitive drum 1 increases. As described above, the dynamic friction coefficient μ is increased and the load applied to the toner is increased, so that toner fusion is likely to occur.

  Furthermore, an experiment was conducted to clarify the contribution of toner, photosensitive drum, and developing roller to the dynamic friction coefficient μ.

  Specifically, the development was made by recombining each with residual toner in the developing unit used for a long time, developing roller used for a long time, photosensitive drum used for a long time, new toner, new developing roller, new photosensitive drum. A device was used. Then, using the developing device, a driving load measurement is performed on the difference between the developing roller driving power when the developing roller and the photosensitive drum are in contact with each other and the developing roller driving power when the developing roller and the photosensitive drum are separated from each other. Measured by means.

  FIG. 15 shows the measurement results. As can be seen from the figure, the difference is greatly influenced by the toner, and the photosensitive drum and the developing roller are only slightly affected. Therefore, it was found that the dynamic friction coefficient μ increases as the toner deteriorates.

  From the above fact, the difference between the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are in contact with the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are separated is measured. Thus, it is possible to detect toner deterioration.

(Description of toner deterioration detection method)
With reference to FIG. 8, a toner deterioration detection method in the present embodiment will be described. FIG. 8 is a schematic configuration diagram of the toner deterioration information detection apparatus according to the present embodiment.

  As shown in FIG. 8, the developing roller 9 is rotationally driven by a developing roller drive motor 51. The toner deterioration information detection device (developer deterioration determination means) 56 includes a motor drive power detection device (drive load measurement means) 52, a detection result recording device (measurement result recording means) 53, and a data processing device (data processing means). 54 and a data comparison device 55. That is, the toner deterioration information detection device 56 constitutes a control unit, a determination unit, and a recording unit.

  The developing device status display device (not shown) displays the status of the developing device 3, but the display content is controlled by the data comparison device 55.

  Hereinafter, a specific method for toner deterioration detection will be described.

First, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with each other and the driving power when the developing roller 9 and the photosensitive drum 1 are separated from each other in the initial stage of use of the developing device is set as a reference value W0. . Then, 1.5 times the reference value W0 is set as the threshold value W1, and recorded in the data comparison device 55. The basis for setting the threshold value W1 to 1.5 times the reference value W0 will be described later.

  At the time of non-image formation before image output, the motor driving power detection device 52, the detection result recording device 53, and the data processing device 54 are used with the developing roller 9 and the photosensitive drum 1 in contact with each other after a predetermined time has elapsed. Detect motor drive power. And these detection results are recorded and the average value W5 is calculated (averaging process). The calculated W5 is recorded in the data comparison device 55.

  Similarly, at the time of non-image formation before image output, the motor driving power detection device 52, the detection result recording device 53, and the data processing device 54 are used while the developing roller 9 and the photosensitive drum 1 are separated from each other for a predetermined time. The motor drive power is detected. Then, the detection result is recorded, and the average value W6 is calculated (averaging process). The calculated W6 is recorded in the data comparison device 55.

  Next, using the data comparison device 55, the magnitude relationship between the difference W5-W6 and the threshold value W1 is compared. If W5−W6 <W1 (if the difference is less than the predetermined threshold), it is determined that the toner has not deteriorated. If W5−W6 ≧ W1 (if the difference is greater than or equal to the predetermined threshold), then the toner is Judge that it is deteriorated. Then, the toner deterioration determination ends.

  As described above, if the difference between the average value of the motor driving power when the developing roller 9 and the photosensitive drum 1 are in contact with the average value of the motor driving power when the developing roller 9 and the photosensitive drum 1 are separated is calculated, a measurement error is calculated. Since the measurement result is stable and the measurement result is stable, toner deterioration can be detected with high accuracy.

(Durability test under actual use conditions)
In order to confirm the durability performance of the developing device 3 in the present embodiment, a durability test was performed under conditions close to actual use conditions. The durability test was performed by filling the developing container 8 with 200 g of toner corresponding to 8000 A4 size images with an image printing ratio of 5%.

  The image for evaluation was an A4 size character pattern with an image printing ratio of 0.5%, 1%, 1.5%, 2%, 3%. In addition, the intermittent mode is set to stop for 5 seconds once every time two images are output. The test environment was a temperature of 23 ° C. and a humidity of 50% RH.

  Here, when the voltages applied to the developing roller 9, the regulating blade 11, and the elastic roller 10 are Vdev, Vb, and Vrs, respectively, Vdev = −300V, Vb = −500V, and Vrs = −300V are set. During the 9 revolutions, the same voltage was always applied.

  When toner fusion to the developing roller 9 and the regulating blade 11 occurs, “fogging” that is an image defect occurs. In order to investigate the occurrence of this “fogging”, the fogging evaluation was performed during the durability test. The fogging evaluation method is as follows.

  That is, the fog density (%) (= Dr (%)) from the difference between the whiteness (reflectance Ds (%)) of the white background portion of the printout image and the whiteness (average reflectance Dr (%)) of the recording material. -Ds (%)) was calculated, and a method for evaluating image fogging was adopted. Here, the whiteness was measured by “REFLECTMETER MODEL TC-6DS” (manufactured by Tokyo Denshoku Co., Ltd.).

In this embodiment, since black toner is used, a green filter is used as a filter used during measurement. In the four-color full-color image forming apparatus, which will be described later in the second to fifth embodiments, the filters used at the time of measurement are amber light for cyan, blue, magenta, and black for yellow. In this case, a green filter was used. In addition, the evaluation of fogging was performed according to the following criteria.
○: Good Less than 3.0% ×: There is a problem 3.0% or more

  Under each image printing ratio condition, the fogging evaluation was performed every time 1000 sheets were printed, and the durability test was performed until the fogging evaluation became x. Table 1 shows the results of the fog evaluation (endurance test evaluation).

  The first line of Table 1 shows the image printing ratio conditions of the durability test. In Table 1, “remaining toner amount”, “developing roller driving power”, “difference between developing roller driving power at the time of contact and developing roller driving power at the time of separation”, and “number of printed sheets” are evaluated by fogging. Each value at the time when the endurance test was completed is indicated by x. Based on this data, various toner deterioration detection methods were determined.

  First, in the present embodiment, in the initial stage of use of the developing device, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with the driving power when the developing roller 9 and the photosensitive drum 1 are separated from each other. Was 2.0 [W].

  Therefore, the reference value W0 = 2.0 [W]. Considering the results in Table 1, if the difference is less than 1.5 times the reference value W0, toner fusion to the developing roller 9 and the regulating blade 11 does not occur. Accordingly, the threshold value W1 = 3.0 [W] is set, and if the difference is less than the threshold value W1, it is determined that the toner in the developing device 3 has not deteriorated. If the difference is equal to or greater than the threshold value W1, the developing device. 3 was determined to be deteriorated. Then, every time 1000 sheets were printed, the toner deterioration was determined.

  Next, as Comparative Example 1, an example in which a threshold value is provided for the image printing ratio to detect toner deterioration will be described. In the case of Comparative Example 1, when the image printing ratio was 2.0%, no image defect occurred, and almost all the toner in the developing device 3 could be consumed.

  Therefore, the threshold value of the image printing ratio is set to 2.0%. When the image printing ratio is 2.0%, X is the number of prints that can consume almost the entire amount of toner in the developing device 3. When output of X images from the start of use of the developing device is completed, it is determined that deteriorated toner has been generated in the developing device 3, and the use of the developing device 3 is stopped.

  Therefore, when the image printing ratio is 2.0% or more, almost all of the toner in the developing device can be consumed, but when the image printing ratio is less than 2.0%, the toner in the developing device 3 is consumed. The entire amount cannot be consumed.

  Further, as Comparative Example 2, an example in which toner deterioration is detected by setting a threshold value for the developing roller driving power will be described. In the case of Comparative Example 2, the developing roller driving power was 6.3 [W] in the early stage of using the developing device. Therefore, the reference value Y0 is set to 6.3 [W].

Considering the results shown in Table 1, if the developing roller driving power is less than 1.3 times that in the initial stage of using the developing device, toner fusion to the developing roller 9 and the regulating blade 11 does not occur. Therefore, since Y0 × 1.3≈8.2, the threshold Y1 = 8.2 [W] is set, and if the difference is less than the threshold Y1,
It was determined that the toner in the developing device 3 was not deteriorated. If the difference was equal to or greater than the threshold Y1, it was determined that the toner in the developing device 3 was deteriorated. Then, every time 1000 sheets were printed, the toner deterioration was determined.

  Under the above conditions, the endurance test was continued until it was detected that the toner deteriorated using the toner deterioration detection methods of the present embodiment, Comparative Example 1 and Comparative Example 2. The durability evaluation method is the same as described above, and the evaluation image is an A4 size character pattern with an image printing ratio of 0.5%, 1%, 1.5%, 2%, and 3%.

  Table 2 shows the remaining amount of toner in the developing device when the toner deterioration is detected using each toner deterioration detection method.

  In any endurance test evaluation, the fogging evaluation did not become x. From this result, it can be seen that when the image printing ratio is 2.0% or more, almost any amount of toner in the developing device 3 can be consumed by any toner deterioration detection method. It can also be seen that when the image printing ratio is 1.5%, the remaining amount of toner in the developing device 3 after detecting that the toner has deteriorated is almost the same no matter which toner deterioration detection method is used.

  However, when the image printing ratio is 0.5% or 1.0%, the toner remaining amount in the developing device 3 is reduced compared to Comparative Example 1 and Comparative Example 2 by using the toner deterioration detection method according to this embodiment. be able to. That is, by applying this embodiment, it is possible to suppress wasteful disposal of a developing device and a developer that can form an image in a good state. This is because the toner deterioration can be detected with high accuracy by measuring only the change in the driving load due to the rubbing between the developing roller 9 and the photosensitive drum 1.

  From the above, by applying this embodiment, a developing device and a developer that can form an image in a good state without causing an image defect under any image printing ratio condition. It is possible to suppress wasteful disposal of the agent.

  In addition, the test environment of Table 1 and Table 2 was performed in the environment of temperature 23 degreeC and humidity 50% RH (henceforth N / N environment).

  Further, the toner deterioration detection method according to the present embodiment is applied in an environment having a temperature of 15 ° C. and a humidity of 10% RH (hereinafter referred to as L / L environment) and an environment having a temperature of 30 ° C. and a humidity of 80% RH (hereinafter referred to as H / H environment). The durability test was conducted.

  Table 3 shows the N / N environment test results in Example 1-1, the L / L environment test results in Example 1-2, and the H / H environment test results in Example 1-3.

  Table 3 shows the remaining amount of toner in the developing device 3 when toner deterioration is detected. In any of the durability test evaluations, the fogging evaluation did not become x.

  As described above, in the same manner as in the N / N environment, in the L / L environment and the H / H environment, by applying the toner deterioration detection method of the present embodiment, a developing device and a developer that can form an image in a good state Can be prevented from being wasted.

(Sequence control under actual use conditions)
With reference to FIG. 1, the sequence control under actual use conditions for preventing the deteriorated toner from fusing to the developing roller 9 and the regulating blade 11 in the present embodiment will be described. FIG. 1 is a sequence control diagram of toner deterioration detection in the image forming apparatus according to the present embodiment.

  First, when an image output command is received in a state of waiting for an image output command (step S1), toner deterioration is detected (step S2). As a result, if toner deterioration is detected (Yes), the process proceeds to step S4. If not detected (No), the process proceeds to step S3, and an image is output.

  When toner deterioration is detected in step S2 (Yes), a developing device replacement request is displayed and image formation is temporarily stopped (step S4). In order to replace the developing device, it is necessary to open and close the door of the image forming apparatus. Therefore, the process waits until the opening and closing of the door is detected (step S5).

  If opening / closing of the door is detected, toner deterioration is detected (step S6). If toner deterioration is detected (Yes), the process returns to step S4. If not detected (No), the process proceeds to step S3 and an image is output. . When the image output in step S3 is completed, the process returns to the image output standby state in step S1.

  By performing the sequence control described above, it is possible to replace the developing device with a normal developing device before the deteriorated toner adheres to the developing roller 9 and the regulating blade 11 and an image defect occurs. As a result, it is possible to prevent image defects due to toner fusion to the developing roller 9 and the regulating blade 11.

(Supplementary explanation of this embodiment)
Hereinafter, the image forming apparatus according to the present embodiment described above will be supplementarily described. Here, (supplementary explanation on toner deterioration detection method), (supplementary explanation on toner deterioration determination method), (supplementary explanation on threshold setting), (supplementary explanation on rotation load of developing roller), (reference value and threshold value) Supplementary explanation regarding the setting method) will be described. Further, (supplementary explanation regarding the detection timing of the driving power of the developing roller), (supplementary explanation regarding the supplementary toner), and (supplementary explanation regarding the peripheral speed ratio between the developing roller and the photosensitive drum) will be described.

(Supplementary explanation on toner deterioration detection method)
In this embodiment, the driving power of the developing roller 9 is measured by measuring the difference between when the developing roller 9 and the photosensitive drum 1 are in contact with each other and when the developing roller 9 and the photosensitive drum 1 are separated from each other. Although toner deterioration is detected, the detection method of the present invention is not necessarily limited to this.

As shown in FIG. 13, like the developing roller driving motor, the photosensitive drum driving motor is also affected by the rubbing between the developing roller 9 and the photosensitive drum 1. Accordingly, with respect to the driving power of the photosensitive drum 1, the toner deterioration is measured by measuring the difference between when the developing roller 9 and the photosensitive drum 1 are in contact with each other and when the developing roller 9 and the photosensitive drum 1 are separated from each other. Can be detected.

  Even when the developing roller 9 and the photosensitive drum 1 are driven by a single motor (driving means), the developing roller 9 and the photosensitive drum 1 are separated from each other when the developing roller 9 and the photosensitive drum 1 are in contact with each other. By measuring the difference with time, toner deterioration can be detected.

  This is because when the toner deteriorates, in the developing portion when the developing roller 9 and the photosensitive drum 1 are in contact with each other, embedding of the external additive on the toner surface and release of the external additive progress, and the electric power is also generated by the friction between the toners. This is because it is consumed.

  Therefore, with respect to at least one of the motor that rotationally drives the photosensitive drum 1 or the developing roller 9, the difference between when the developing roller 9 and the photosensitive drum 1 are in contact with each other and when the developing roller 9 and the photosensitive drum 1 are separated from each other. By measuring the toner deterioration can be detected.

(Supplementary explanation regarding the method for determining toner deterioration)
In this embodiment, the difference between the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are in contact with the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are separated from each other is calculated. By measuring, toner deterioration was detected.

  However, the toner deterioration determination method in the present invention is not limited to this. That is, instead of calculating the difference in drive power, toner deterioration may be detected from the drive power ratio at the time of contact and separation.

  In the present embodiment, if the difference between the contact time and the separation time is less than the threshold value W1, it is determined that the toner has not deteriorated. If the difference between the contact time and the separation time is equal to or greater than the threshold value W1, It was determined that the toner was deteriorated.

According to this, if the developing roller surface peripheral speed V1> the photosensitive drum surface peripheral speed V2, the difference between the contact time and the separation time is always positive, so the determination method described in this embodiment may be used. However, as in the case where the developing roller surface peripheral speed V1 <the photosensitive drum surface peripheral speed V2, there is a possibility that the difference between the contact time and the separation time becomes negative.

  Therefore, the absolute value of the difference between contact and separation is compared with the threshold value W1 so that the deteriorated toner can be accurately determined even if the magnitude relationship between the developing roller surface peripheral speed V1 and the photosensitive drum surface peripheral speed V2 changes. The determination method to do may be used. That is, if the absolute value of the difference between the contact time and the separation time is less than the threshold value W1, it is determined that the toner has not deteriorated. If the absolute value of the difference between the contact time and the separation time is equal to or greater than the threshold value W1, It was determined that the toner was deteriorated.

(Supplementary explanation on threshold setting)
Although one threshold value is set in the present embodiment, the threshold value setting in the present invention is not necessarily limited thereto. For example, two threshold values may be set.

  In the initial stage of use of the developing device, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with the driving power when the developing roller 9 and the photosensitive drum 1 are separated is 2.0 [W]. there were. However, considering the results shown in Table 1, toner fusion to the developing roller 9 and the regulating blade 11 does not occur if the difference is less than 1.5 times the initial use of the developing device.

Thus, 1.3 times the initial use of the developing device may be set as the first threshold value, and 1.5 times may be set as the second threshold value. That is, the threshold value W3 = 2.6 [W] and the threshold value W4 = 3.0 [W] are set. If the difference is less than the threshold value W3, “development apparatus normal” is displayed, and the difference is greater than or equal to the threshold value W3 and less than W4. Then, “Shortly developed device replacement request” is displayed. Further, if the difference is equal to or greater than the threshold value W4, “development device replacement request” is displayed and image formation is temporarily stopped.

  As a result, “development device replacement request” is displayed, and the user can prepare to replace the developing device 3 before temporarily suspending image formation. Therefore, the developing device 3 can be immediately replaced with a new one, and the image forming device 100 Unusable time can be shortened as much as possible.

(Supplementary explanation regarding rotational load of developing roller)
In this embodiment, as a method of detecting the rotational load of the developing roller 9, a method of detecting the driving power of the motor that rotationally drives the developing roller 9 is adopted. However, the method of detecting the rotational load of the developing roller 9 in the present invention is employed. This is not necessarily the case.

  For example, a method of detecting a current necessary for driving a motor may be used. Thereby, the rotation load of the developing roller 9 can be detected in the same manner as the detection of the motor power. Moreover, the method of detecting the driving torque required when driving a motor may be used.

(Supplementary explanation on how to set the reference value and threshold)
In this embodiment, in the initial stage of use of the developing device, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with the driving power when the developing roller 9 and the photosensitive drum 1 are separated is W0. = 2.0 [W].

  Considering the results shown in Table 1, toner fusion to the developing roller 9 and the regulating blade 11 does not occur if the difference is less than 1.5 times the initial stage of use of the developing device. Therefore, the threshold value W1 = 3.0 [W] was set. However, the setting method of the reference value W0 and the threshold value W1 is not limited to this.

  For example, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with a plurality of developing devices 3 and the driving power when the developing roller 9 and the photosensitive drum 1 are separated are calculated. The average value may be W0.

  When this method is used, it is hardly affected by the history of the developing device 3 from the start of production until the start of use, and performance errors and settings of various members in the developing device 3 such as the developing roller 9 and the regulating blade 11 are set. The reference value W0 and the threshold value W1 can be set with almost no influence of errors. Therefore, toner deterioration can be detected stably.

  Further, after the start of use of the developing device 3 and the output of a predetermined number of images, the load for rotating the developing roller 9 is stabilized. Therefore, at this time, the difference between the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact with the driving power when the developing roller 9 and the photosensitive drum 1 are separated is calculated, and the average value is calculated as W0. It is good.

  Further, the threshold value W1 does not have to be 1.5 times the reference value W0, and an appropriate constant multiple may be determined for each developing device and toner.

(Supplementary explanation regarding detection timing of developing roller drive power)
In this embodiment, the developing roller driving power is detected before image formation, but the detection timing of the developing roller driving power in the present invention is not necessarily limited to this. That is, not only before image formation, but also at any timing as long as non-image formation is performed.

For example, after the image forming operation is completed, the developing roller driving power may be detected during the rotation after the developing roller 9 is driven in a non-sheet-passing state. Alternatively, the developing roller driving power may be detected at a timing corresponding to the interval between sheets on the photosensitive drum 1. Here, the “inter-paper space” means a space between the recording material and the recording material that are continuously conveyed when image formation is continuously performed.

  The reason for detecting the developing roller driving power during non-image formation is as follows.

  At the time of non-image formation, the photosensitive drum surface potential is charged to about −500 V, a −300 V voltage is applied to the core of the developing roller 9, and the toner is a negatively charged toner. Passes through the developing section while adhering to the surface. That is, the peripheral speed difference is always generated between the toner layer on the developing roller 9 and the surface of the photosensitive drum 1. Therefore, the developing roller driving power is stabilized.

  However, during image formation, toner between the developing roller 9 and the photosensitive drum 1 in the developing unit adheres to the developing roller 9 and can also adhere to the photosensitive drum 1. Accordingly, the dynamic friction coefficient μ between the developing roller 9 and the photosensitive drum 1 becomes unstable, and the increase or decrease in driving power accompanying the rubbing between the developing roller 9 and the photosensitive drum 1 becomes unstable, and the developing roller driving power is not stable. .

  As described above, in order to detect a stable developing roller driving power, it is preferable to detect the developing roller driving power during non-image formation. However, it is a matter of course that the detection timing for detecting toner deterioration may be used during image formation or when developing toner from the developing roller 9 to the photosensitive drum 1.

(Supplementary explanation regarding replenishment toner)
In the present embodiment, the regular charging polarity of the replenishment toner is negative, but the replenishment toner in the present invention is not limited to this. Instead of the negatively charged toner, a toner having a normal charging polarity of positive polarity may be used. In that case, what is necessary is just to change the polarity of the voltage applied to members, such as the charging roller 2, the developing roller 9, the control blade 11, and the elastic roller 10, as needed.

(Supplementary explanation on the peripheral speed ratio between the developing roller and the photosensitive drum)
In this embodiment, the developing roller peripheral speed V2 = 300 [mm / s], the photosensitive drum peripheral speed V1 = 200 [mm / s], and the developing roller peripheral speed / photosensitive drum peripheral speed (V2 / V1) = 1. However, the ratio of the peripheral speeds in the present invention is not necessarily limited to this.

  FIG. 16 shows the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are in contact with the developing roller peripheral speed / photosensitive drum peripheral speed, and development when the developing roller 9 and the photosensitive drum 1 are separated from each other. It is a figure which shows the difference change with roller drive electric power.

  As shown in FIG. 16, when the developing roller peripheral speed / photosensitive drum peripheral speed is 0.95 or less or 1.05 or more, the developing roller driving power when the developing roller 9 and the photosensitive drum 1 are in contact with each other, It is possible to measure the difference in the developing roller driving power when separated.

  However, when the developing roller peripheral speed / photosensitive drum peripheral speed is 0.95 or less, the difference is negative, and when it is 1.05 or more, the difference is positive. Therefore, toner deterioration can be reliably detected by comparing the absolute value of the difference with a threshold value.

[Second Embodiment]
A second embodiment of the present invention will be described with reference to FIG.

  In the first embodiment, the image forming apparatus 100 has been described as a monochromatic image forming apparatus. However, the image forming apparatus according to the present invention is not limited to this, and can form a full-color image. It may be an image forming apparatus.

  That is, the image forming apparatus according to the present embodiment is a color image forming apparatus capable of forming a multicolor image such as a full color image by using an electrophotographic system.

  The image forming apparatus according to the present embodiment is provided with a plurality of developing devices corresponding to the toners of the respective colors, and each developing device is provided with a rotatable image carrier. When forming an image, the electrostatic latent images sequentially formed on the photoconductor are sequentially developed in each developing device.

  The toner images formed on the respective photoreceptors are directly transferred onto the recording material, or once transferred onto the intermediate transfer member and then transferred onto the recording material. At the time of this transfer, the toner images are transferred in an overlapping manner, whereby a color image having a desired color tone is formed on the recording material or the intermediate transfer belt.

  Further, a developing device may be provided for each color toner on a single photoconductor, and a toner image having a desired color tone may be developed on the single photoconductor. The color image developed on the photoreceptor in such a configuration is then transferred to a recording material.

  FIG. 4 shows a schematic configuration of the image forming apparatus according to the present embodiment. As shown in FIG. 4, the image forming apparatus according to the present embodiment is a color image forming apparatus having a plurality of image forming units corresponding to the respective color toners and capable of forming a four-color full-color image.

  A color image forming apparatus 200 shown in FIG. 4 has first, second, third, and fourth image forming units for forming images of cyan, yellow, magenta, and black as a plurality of image forming units, respectively. Have The process cartridges 19A, 19B, 19C, and 19D correspond to the first, second, third, and fourth image forming units, respectively.

  Since the configuration and operation of each image forming unit are substantially the same as those in the first embodiment except that the color of the toner used is different, the description thereof is omitted. In the following description, if there is no particular distinction, subscripts A, B, C, and D given to the reference numerals in FIG. 4 are used to indicate elements provided for any of the toner colors. Omitted and will be described in general.

  The image forming apparatus 200 includes a photosensitive drum 1 as an image carrier in each of four image forming units arranged in parallel in the vertical direction. The photosensitive drum 1 is rotationally driven by a drive motor (not shown) in the direction of the arrow.

  Around the photosensitive drum 1, a charging roller 2, an exposure device 6, a developing device 3, an electrostatic transfer device 18, a cleaning blade 5, and the like are arranged in order according to the rotation direction. The operation of the developing device 3 is the same as that of the image forming apparatus 100 of FIG. 3 described in the first embodiment. The charging roller 2 uniformly charges the surface of the photosensitive drum 1.

  The exposure device 6 irradiates a laser based on the image information and forms an electrostatic latent image on the photosensitive drum 1. The developing device 3 develops the electrostatic latent image as a developer image (toner image). The electrostatic transfer device 18 transfers the toner image on the photosensitive drum 1 to the recording material P. The cleaning blade 5 removes transfer residual toner remaining on the surface of the photosensitive drum 1 after transfer.

  The photosensitive drum 1, the charging roller 2 as a process unit that acts on the photosensitive drum 1, the developing device 3, the cleaning blade 5, and the waste toner container 13 are integrally formed into a cartridge to form a process cartridge 19. The process cartridge 19 is detachable from the main body of the image forming apparatus 200.

  In this embodiment, the process cartridges 19A, 19B, 19C, and 19D all have the same shape and the same configuration, but the toners contained therein are cyan, yellow, magenta, and black, respectively. is there.

  A recording material conveyance belt (electrostatic conveyance belt) 22 as a recording material carrier that circulates and moves is disposed so as to face and contact all the photosensitive drums 1. Corresponding to the four photosensitive drums 1, the transfer roller 4 as a transfer member that contacts the inside of the electrostatic conveyance belt 22 is juxtaposed.

  The transfer roller 4 abuts on the photosensitive drum 1 via the electrostatic conveyance belt 22 to form a transfer portion. A positive charge is applied to the recording material P from the transfer roller 4 via the electrostatic conveyance belt 22, and a negative toner on the photosensitive drum 1 is applied to the recording material P in contact with the photosensitive drum 1 by an electric field generated by this charge. Is transcribed.

  Further, the image forming apparatus 200 is provided with a fixing device 7 that fixes a plurality of toner images transferred to the recording material P. The recording material P to which the toner image on the photosensitive drum 1 is transferred is applied with heat and pressure when passing through the fixing device 7. As a result, the toner images of a plurality of colors are permanently fixed on the surface of the recording material P.

  The developing device 3 in the color image forming apparatus 200 shown in FIG. 4 is the same as that described with reference to FIG. 2 in the first embodiment, and the toner is a non-magnetic one-component developer. Used. However, the toner in the present invention is not limited to this, and a magnetic one-component developer may be used.

  Next, details of a method of driving the developing roller 9 will be described.

  In the present embodiment, a motor (not shown) is used as a driving unit for the developing roller 9. In addition, the developing roller 9, the elastic roller 10, and the stirring member 12 in the developing device are also rotationally driven by this motor.

  However, for the driving of the photosensitive drum 1 and the electrostatic conveyance belt 22, a rotation driving unit different from the motor for driving the developing roller 9 is used. In this embodiment, in order to reduce the number of motors, each of the cyan, yellow, magenta, and black developing devices is driven by one motor.

  Next, it will be shown that the remaining amount of toner in the developing device differs when the toner is detected to be deteriorated depending on the type of toner deterioration detection method.

  First, in the present embodiment, as in the first embodiment, the driving power when the developing roller 9 and the photosensitive drum 1 are brought into contact in the initial stage of use of the developing device, the developing roller 9 and the photosensitive drum 1 are The difference from the driving power when separated was 2.0 [W].

  Therefore, the reference value W0 = 2.0 [W]. Considering the results of Table 1, if the difference is less than 1.5 times the reference value W0, toner fusion to the developing roller 9 and the regulating blade 11 does not occur.

  Accordingly, the threshold value W1 = 3.0 [W] is set, and if the difference is less than the threshold value W1, it is determined that the toner in the developing device 3 has not deteriorated. If the difference is equal to or greater than the threshold value W1, the developing device. The toner inside was determined to be deteriorated.

  Each time 1000 sheets were printed, toner deterioration was determined for each of the cyan, yellow, magenta, and black developing devices.

  Next, as Comparative Example 3 (Comparative Examples 1 and 2 refer to the first embodiment described above and Table 2), a method is set for detecting the presence or absence of deteriorated toner by providing a threshold value for the developing roller driving power.

  In the initial stage of use of the developing device, the developing roller driving power was 24.9 [W]. Therefore, the reference value Y0 = 24.9 [W] is set. Considering the results in Table 1 above, if the developing roller driving power is less than 1.3 times that in the initial stage of using the developing device, toner fusion to the developing roller 9 and the regulating blade 11 does not occur.

  Therefore, the threshold value Y1 = 32.4 [W] is set, and if the difference is less than the threshold value Y1, it is determined that the toner in the developing device is not deteriorated. The toner was determined to be deteriorated. Then, every time 1000 sheets were printed, the toner deterioration was determined.

  The durability test was continued until the deteriorated toner was detected using the toner deterioration detection method of the present embodiment and comparative example 3. The durability evaluation method is the same as described above, and the evaluation image is an A4 size character pattern with an image printing ratio of 0.5%, 1%, 1.5%, 2%, and 3%.

  Table 4 shows the remaining amount of toner in the developing device when toner deterioration is detected using each toner deterioration detection method.

  In Table 4 above, in any of the durability test evaluations, the fogging evaluation did not become x. From this result, it can be seen that when the image printing ratio is 2.0% or more, almost any amount of toner in the developing device can be consumed by any toner deterioration detection method.

  However, when the image printing ratio is 0.5%, 1.0%, or 1.5%, the toner remaining amount in the developing device is reduced as compared with Comparative Example 3 by using the toner deterioration detection method of the present embodiment. be able to. That is, by applying this embodiment, it is possible to suppress wasteful disposal of a developing device and a developer that can form an image in a good state.

(Supplementary explanation of the second embodiment)
In this embodiment, in order to reduce the number of motors, each of the cyan, yellow, magenta, and black developing devices is driven by one motor.

  In this case, as in the endurance test conditions of the present embodiment, if the start of use of the developing device is the same and the usage frequency of each color of cyan, yellow, magenta, and black is the same, the deteriorated toner is determined by the absolute value of the developing roller driving power. May be detected.

  However, under actual usage conditions, the timing at which a used developing device is replaced with a new developing device and the new developing device starts to be used differs depending on the developing device, and the use frequency of each color of cyan, yellow, magenta, and black Is also different.

  Therefore, in such a case, even if the deteriorated toner is detected based on the absolute value of the developing roller driving power, it is not known in which developing device the toner is deteriorated. In such a case, the developing devices for all four colors must be replaced, and a developing device and a developer that can form an image in a good state must be wasted.

When only one developing device has toner deterioration, the developing roller driving power is approximately 6.3 × 1.0 × 3 + 6.3 × 1.3 × 1 = 27.1 W. Therefore, the threshold value Y1
= 32.4 W has not been reached, so toner deterioration cannot be detected.

  Even in such a case, as in the present invention, for each developing device, the developing roller 9 and the photosensitive drum 1 are brought into contact with and separated from each other, whereby it is possible to determine in which developing device the toner deterioration has occurred.

[Third Embodiment]
An image forming apparatus according to a third embodiment of the present invention will be described with reference to FIGS.

  In the first and second embodiments, the developing device is not provided with a replenishing mechanism (developer replenishing means), but the image forming apparatus according to the present invention is not limited to this.

  FIG. 6 is a schematic configuration diagram of the image forming apparatus according to the present embodiment. As shown in FIG. 6, the image forming apparatus according to the present embodiment is an apparatus capable of forming a full-color image having a plurality of image forming units, and the developing device includes a toner supply mechanism. It is a feature. A schematic configuration of this developing apparatus is shown in FIG.

  The only difference between the present embodiment and the first and second embodiments is that the developing device includes a replenishment mechanism. That is, the configuration other than the replenishment mechanism of the developing device is not different from the first and second embodiments, so that the description thereof is omitted.

  As shown in FIG. 5, the developing device 3 according to the present embodiment includes a developing roller 9 as a developer carrier, an elastic roller 10 as a developer supply member, a regulating blade 11 as a layer thickness regulating member, and a developing chamber 31. And a developing chamber stirring member 32. Further, a toner storage chamber 33 as a developer storage chamber and a toner storage chamber stirring member 34 are provided.

  The developing chamber 31 is provided so as to include the developing roller 9. The developing chamber stirring member 32 is rotatably provided so as to stir the toner T in the developing chamber 31. The toner storage chamber 33 is provided so as to be connected (communicated) with the developing chamber 31 through the opening 42. The toner storage chamber stirring member 34 is provided to stir the toner T in the toner storage chamber 33. The developing chamber 31 can hold a maximum of 50 g of toner.

  The toner storage chamber 33 includes a toner storage chamber stirring member 34 and a toner supply roller 41. The toner T stirred by the toner storage chamber stirring member 34 is supplied to the toner supply roller 41. The toner supply roller 41 rotates during toner supply control, which will be described later, and supplies toner T to the developing chamber 31 through the opening 42.

  When the toner is consumed from the developing chamber 31, the toner is sequentially replenished from the toner storage chamber 33, and the inside of the developing chamber 31 is controlled so that the toner is always 50g.

The toner deterioration detection method in the present embodiment is the same as that in the first embodiment. The difference is the sequence control for toner deterioration detection after detecting that the toner is deteriorated. Hereinafter, the sequence control of toner deterioration detection in the present embodiment will be described with reference to FIG.

  First, it starts from a state of waiting for an image output command (step S1). Next, when an image output command is received, toner deterioration is detected (step S2). If Yes, the process proceeds to step S4, and if No, the process proceeds to step S3 to output an image.

  If Yes in step S2, 5 g of toner is discharged from the developing chamber by a developer discharge means (not shown) (step S4). Next, 5 g of toner is supplied from the toner storage chamber to the developing chamber (step S5). Toner deterioration detection is performed (step S6). If Yes, the process returns to step S4. If No, the process proceeds to step S3 to output an image. When the image output in step S3 ends, the process returns to the image output standby state in step S1.

  By performing the sequence control described above, a part of the toner in the developing chamber can be replaced with a new toner before the deteriorated toner adheres to the developing roller 9 and the regulating blade 11 and an image defect occurs. Further, when new toner is supplied into the developing chamber, the deteriorated toner does not continue to adhere to the developing roller 9 and the regulating blade 11. Thereby, it is possible to prevent image defects due to toner fusion to the developing roller 9 and the regulating blade 11.

(Supplementary explanation of the third embodiment)
In the present embodiment, toner discharge from the developing chamber 31 and toner replenishment from the toner storage chamber 33 to the developing chamber 31 are continuously performed. However, the timing of toner replenishment in the present invention is not necessarily limited to this.

  For example, when toner deterioration is detected, the toner can be supplied from the toner storage chamber 33 to the developing chamber 31 without discharging the toner from the developing chamber 31. The toner supply from the toner storage chamber 33 to the developing chamber 31 may be performed.

(Combination with other toner deterioration detection methods)
In this embodiment, toner deterioration is detected by using a difference between a driving load when the developing roller 9 and the photosensitive drum 1 are brought into contact with each other and a driving load when the developing roller 9 and the photosensitive drum 1 are separated from each other. However, in addition to the above method, other toner deterioration detection methods may be used in combination. By using two or more types of toner deterioration detection methods, more accurate toner deterioration detection can be performed.

  In the following, a method for detecting toner deterioration based on the total number of output images of the developing device and the total rotation time of the developing roller as history information of the developing device will be described.

  However, after detecting toner deterioration by this method, the difference between the driving load when the developing roller 9 and the photosensitive drum 1 are brought into contact with the driving load when the developing roller 9 and the photosensitive drum 1 are separated is used. Thus, toner deterioration may be detected. Thereby, the number of times of toner deterioration detection of the present invention can be reduced, and the time for operating the image forming apparatus during non-image formation can be reduced.

  An example of a method for detecting toner deterioration based on the total number of output images of the developing device and the total rotation time of the developing roller will be described below.

  FIG. 9 is a diagram for explaining the toner deterioration information detecting device 67 in the present embodiment. As shown in FIG. 9, the toner deterioration information detecting device 67 includes an image signal processing circuit 61, a developing roller travel distance measuring circuit 62, a counter 63, a CPU 64, a RAM 65, and a ROM 66. The developing roller travel distance, which is history information of the developing device, is measured by the developing roller travel distance measuring circuit 62 and recorded in the CPU 64.

  The toner deterioration information detecting device 67 constitutes a control unit, a determination unit, and a travel distance deriving unit.

  The digital image signal to be printed is sent to the image signal processing circuit 61, where it is converted into a pixel image signal of 8 bits (256 values) having an output level corresponding to the density of each pixel.

  Pixel image signals corresponding to the density of each pixel are integrated by the counter 63. Here, the integration signal S1 from the counter 63 corresponds to the amount of toner consumed from the developing container 8 to form a toner image.

  Therefore, the integration signal S1 is supplied to the CPU 64 and stored in the RAM 65. Here, the developing device is set so that 200 g is consumed when 8000 sheets of an A4 size image with a print ratio of 5% are output.

  At this time, when printing at 600 dpi, the integrated signal of the pixel image signal when printing 8000 sheets in A4 size, 7128 × 5040 dots is T1.

This
(Estimated toner consumption at integration signal S1) = 200 × (S1 / T1)
Can be calculated as Therefore, T1 is recorded in the ROM 66.

  The inventors of the present invention have confirmed that the toner deterioration level is substantially proportional to the integrated value of the developing roller travel distance, that is, “rotation time × peripheral speed”.

  Here, the peripheral speed of the developing roller 9 is defined as the rotational speed of the developing roller surface. Therefore, a toner deterioration index considering the amount of toner consumed or discharged from the developing chamber 31 and the amount of toner replenished from the toner storage chamber 33 to the developing chamber 31 is set as S3.

  That is, it is determined that the toner in the developing chamber 31 is deteriorated as the value increases.

  A method for calculating the toner deterioration index S3 (developer deterioration index S3) will be described below.

  The developing roller travel distance integrated value S2 is calculated by the developing roller travel distance measurement circuit 62 that measures the rotation time and the peripheral speed of the developing roller 9 and can calculate the multiplication of the rotation time and the peripheral speed.

  In the present embodiment, in the A4 size, when the image is continuously output in the intermittent mode in which the image is stopped once every time two images are output, it is determined that the toner is deteriorated. . Based on the total number of images output from the developing device and the total rotation time of the developing roller, the determination of detecting toner deterioration was made every time 100 sheets were printed.

  The developing chamber 31 can contain a maximum of 50 g of toner.

  When 100 sheets of A4 size and 100% solid images are output, the estimated toner consumption is 50 g. Therefore, assuming that the estimated toner consumption amount from the developing chamber 31 when printing 100 sheets is X1 and the toner amount in the developing chamber 31 (the maximum amount of toner that can be stored in the developing chamber 31) is X2, X2 ≧ X1 is always satisfied. Fulfill.

  The number of printed sheets was counted by a printed sheet counter 69. Here, T2 is an integrated value of the developing roller travel distance when 100 images are output in the intermittent mode in which the image is output once every time two images are output in the A4 size. Therefore, T2 is recorded in the ROM 66.

In this case, in the above image output condition,
(Estimated toner consumption when 100 sheets are output)
= (100/8000) x (1.5 / 5) x 200
= 0.75g
(Developing roller travel distance when outputting 100 sheets) = T2
It becomes.

  Therefore, when 100 images with an image printing ratio of 1.5% are printed, it is estimated that 0.75 g of toner is consumed.

  When the toner in the developing chamber 31 is consumed, the toner supply roller 41 is driven to rotate until the toner remaining amount detection sensor 43 provided in the developing chamber 31 indicates that 50 g of toner is in the developing chamber. New toner is sequentially replenished from the toner storage chamber 33 to the developing chamber 31. Here, the toner remaining amount detection sensor 43 constitutes a developer consumption amount deriving unit.

Considering such toner change in the developing chamber, the developing roller travel distance when a certain number of sheets are output is L1, the estimated toner consumption from the developing chamber when a certain number of sheets is output is X1, and the toner amount in the developing chamber is As X2,
Toner deterioration index S3 = L1 × (X2−X1) / X2
It is defined as Note that since X2 ≧ X1 is always satisfied, S3 ≧ 0.

Here, when 100 images with an image printing ratio of 1.5% are printed, it is estimated that 0.75 g of toner is consumed,
Toner deterioration index threshold value T3 = T2 × (50−0.75) / 50
Can be calculated as

  Therefore, when the toner deterioration index S3 exceeds the threshold T3 of the toner deterioration index, it is determined that the toner is deteriorated. This determination is performed by the CPU 64. The toner deterioration index S3 is stored in the RAM 65 after the toner deterioration determination.

  Further, the integrated signal S1 of the pixel image signal and the integrated value S2 of the developing roller travel distance are reset to 0. Then, the toner deterioration determination ends. The print number counter 69 is reset to zero. Every time an image is output, S1 and S2 are integrated, and the print number counter 69 also counts the number of prints.

  Next, a change in the toner deterioration index S3 when toner is supplied to the developing chamber 31 will be exemplified. The developing roller 9 develops the deteriorated toner for 5 g (equivalent to 10 A4 solid images) onto the photosensitive drum 1 and discharges it from the developing chamber 31. Thereafter, 5 g new toner is supplied from the toner storage chamber 33 to the developing chamber 31.

  In this case, assuming that the toner deterioration index before discharging and replenishing toner from the developing chamber 31 is S3 ′, and the toner deterioration index after discharging and replenishing toner from the developing chamber 31 is S3 ″, S3 ″ = S3 ′. X (45/50) = 0.9 * S3 '. That is, the toner deterioration index S3 can be lowered.

  An n + 1th toner deterioration detection method after starting to use the developing device 3 will be described below.

  The toner degradation index for the nth time is [S3] n. [S3] n is stored in the RAM 65 after the nth toner deterioration determination.

  From the nth toner deterioration determination to the (n + 1) th time, (the estimated toner consumption amount of the integration signal S1 of the pixel image signal) = 200 × (S1 / T1).

Therefore, the n + 1th toner deterioration index is
[S3] n + 1 = ([S3] n + S2) × (W2−W1) / W2
= ([S3] n + S2) × (50−200 × (S1 / T1)) / 50
It is.

  [S3] If n + 1 exceeds the threshold value T3 of the toner deterioration index, it is determined that the toner has deteriorated. This determination is performed by the CPU 64. The operation after the determination is as described above.

  The toner deterioration index [S3] n + 1 is stored in the RAM 65 after the toner deterioration determination. Further, the integrated signal S1 of the pixel image signal and the integrated value S2 of the developing roller travel distance are reset to 0. Then, the toner deterioration determination ends. The print number counter 69 is reset to zero.

  Based on the total number of images output from the developing device and the total rotation time of the developing roller, a more accurate toner deterioration detection can be performed by using the method of detecting deteriorated toner and the toner deterioration detecting method of the present invention in combination. It becomes possible.

[Fourth Embodiment]
An image forming apparatus according to a fourth embodiment of the present invention will be described with reference to FIGS.

  In the third embodiment, the toner remaining amount detection sensor 43 is provided in the developing chamber 31. When the toner in the developing chamber 31 is consumed, the toner replenishing roller 41 is rotated so that toner is replenished from the toner storage chamber 33 to the developing chamber 31 by the consumed amount.

  However, the configuration of the image forming apparatus according to the present invention is not limited to controlling toner supply from the toner storage chamber 33 to the developing chamber 31. In other words, the image forming apparatus may include a developing device that does not perform toner supply control.

  FIG. 7 is a cross-sectional view illustrating a schematic configuration of the developing device 44 that does not perform toner supply control from the toner storage chamber 33 to the developing chamber 31.

  In the developing device 44, the toner storage chamber 33 is located above the development chamber 31, the opening 42 is always open, and the development chamber stirring member 32 and the toner storage chamber stirring member 34 are always rotated. Here, the developing chamber stirring member 32 is a mylar sheet having a hole, and the toner storage chamber stirring member 34 is a metal rod.

  When such a configuration is adopted, when the toner in the developing chamber 31 is consumed, the toner can be replenished from the toner storage chamber 33 to the developing chamber 31 due to the weight of the toner.

  Since the toner deterioration detection method of the present embodiment is the same as that of the first embodiment, description thereof is omitted. Here, only the operation after detecting that the toner has deteriorated, which is different from the first embodiment, will be described.

  FIG. 11 is a sequence control diagram for detecting toner deterioration of the image forming apparatus according to the present exemplary embodiment.

  It starts from a state of waiting for an image output command (step S1). When an image output command is received, toner deterioration is detected (step S2). If Yes, the process proceeds to step S4, and if No, the process proceeds to step S3 to output an image.

  If Yes in step S2, 5 g of toner is discharged from the developing chamber (step S4). Toner deterioration detection is performed (step S5). If Yes, the process returns to step S4. If No, the process proceeds to step S3 to output an image. When the image output in step S3 ends, the process returns to the image output standby state in step S1.

  In the developing device 44 according to the present embodiment, the toner is replenished from the toner storage chamber 33 to the developing chamber 31 by the amount of toner consumed by simply discharging the toner from the developing chamber 31 in step S4.

  Thus, by performing the sequence control described above, a part of the toner in the developing chamber can be replaced with new toner before the deteriorated toner adheres to the developing roller 9 and the regulating blade 11 and an image defect occurs. it can. Thereby, it is possible to prevent image defects due to toner fusion to the developing roller 9 and the regulating blade 11.

[Fifth Embodiment]
With reference to FIG. 12, an image forming apparatus according to a fifth embodiment of the present invention will be described.

  In the first embodiment, the developer replacement request is displayed after detecting that the toner is deteriorated, and the user replaces the developer. However, the configuration of the image forming apparatus according to the present invention is not necessarily limited. This is not the case.

  For example, after detecting that the toner has deteriorated, the image forming condition may be changed by an image forming condition control unit (not shown).

  Usually, the higher the image forming speed, the higher the temperature in the image forming apparatus, so the toner temperature in the developing device also tends to increase. Also, the amount of toner rubbed per unit time is large. Therefore, after detecting that the toner has deteriorated, an image may be output under image forming conditions with a smaller load on the toner.

  FIG. 12 is a sequence control diagram of toner deterioration detection of the image forming apparatus according to the present embodiment. Here, the normal peripheral speed of the photosensitive drum is V.

  It starts from a state of waiting for an image output command (step S1). When an image output command is received, toner deterioration is detected (step S2). If Yes, the process proceeds to step S4, and if No, the process proceeds to step S3 to output an image. If Yes in step S2, the photosensitive drum peripheral speed is set to V / 2, which is half the normal speed (step S4).

  Toner deterioration detection is performed (step S5). If Yes, the process proceeds to step S6. If No, the process proceeds to step S3 to output an image. In step S6, image output is stopped for a fixed time. Thereafter, the process proceeds again to step S4 and step S5.

When the image output in step S3 is completed, the photosensitive drum peripheral speed is set to the normal speed V (step S7). Thereafter, the process returns to the image output standby state in step S1.

  In this embodiment, after detecting that the toner has deteriorated, the photosensitive drum peripheral speed can be set to V / 2, which is half the normal speed, and the load on the toner can be further reduced. Still, when toner deterioration is detected, image output is stopped for a certain period of time, the temperature of the toner is lowered, and image output is performed under conditions where toner fusion is less likely to occur.

  As described above, by performing the sequence control described above, it is possible to prevent the defective toner from adhering to the developing roller 9 and the regulating blade 11 to cause image defects. Further, it is possible to prevent image defects due to toner fusion to the developing roller 9 and the regulating blade 11.

  In this embodiment, after detecting that the toner has deteriorated, the peripheral speed of the photosensitive drum is made slower than the normal speed to prevent the occurrence of toner fusion. The configuration of the apparatus is not necessarily limited to this.

  That is, when the toner deteriorates, the adhesion force of the toner to the developing roller 9 increases, and the toner tends to adhere excessively to the developing roller 9. In the portion where the toner is excessively adhered, the toner is not sufficiently charged, and “fogging” occurs in which the toner moves to the image white background portion of the photosensitive drum 1.

  Therefore, by changing the voltage applied to the regulating blade 11 when it is detected that the toner is deteriorated, the “fogging” may be prevented by increasing the regulating force of the regulating blade 11.

  For example, if the voltages applied to the developing roller 9 and the regulating blade 11 are Vdev and Vb, respectively, Vdev = −300V and Vb = −500V are set before the toner deterioration is detected, and Vdev is detected after the toner deterioration is detected. = -300V, Vb = -400V may be set.

  Thereby, the electric field at the contact portion between the developing roller 9 and the regulating blade 11 can be reduced, and the force for moving the negatively charged toner from the regulating blade 11 side to the developing roller 9 side can be reduced.

  Similarly, when it is detected that the toner is deteriorated, the voltage applied to the elastic roller 10 is changed to reduce the supply of negatively charged toner from the elastic roller 10 to the developing roller 9, thereby causing “fogging”. It may be prevented.

  For example, the voltages applied to the developing roller 9 and the elastic roller 10 are set as Vdev and Vrs, respectively, and are set to Vdev = −300 V and Vrs = −300 V before the toner deterioration is detected, and Vdev = − after the toner deterioration is detected. You may set to 300V and Vrs = -200V. As a result, the force for moving the negatively charged toner from the developing roller 9 side to the elastic roller 10 side can be increased.

  Further, when the toner deteriorates, the adhesion force of the toner to the photosensitive drum 1 increases. For this reason, when the voltage applied to the transfer roller 4 is not changed from the beginning of use of the image forming apparatus, the efficiency of transferring the toner from the photosensitive drum 1 to the paper decreases.

  Therefore, when it is detected that the toner is deteriorated, the voltage applied to the transfer roller 4 is changed to increase the electric field for transferring the negatively charged toner from the photosensitive drum 1 to the paper, thereby preventing the transfer efficiency from being lowered. May be.

For example, assuming that the voltage applied to the transfer roller 4 is Vt, before the toner deterioration is detected, Vt
= 1500V, and after detecting toner deterioration, Vt = 2000V may be set. When the transfer voltage is controlled by the transfer current, the transfer current after the toner deterioration detection may be made larger than the transfer current before the toner deterioration detection. As described above, any change in conditions may be used as long as the image forming conditions are changed to prevent image defects due to toner deterioration.

[Other embodiments]
The embodiment of the present invention is not limited to the first to fifth embodiments.

  For example, in each of the above-described embodiments, the photosensitive drum 1, the developing device 3, the charging roller 2, the cleaning blade 5, and the waste toner storage container 13 are integrally formed into a cartridge that is detachable from the image forming apparatus main body 200. Process cartridge 19 was obtained.

  However, the present invention also applies to an image forming apparatus having a configuration in which the photosensitive drum 1 is fixedly disposed on the main body of the image forming apparatus and only the developing device 3 is replaced as a cartridge 19 (developing cartridge) that is detachable from the main body of the image forming apparatus. Can be applied.

  Alternatively, the present invention can be similarly applied to an image forming apparatus configured to fix the developing device 3 to the main body of the image forming apparatus and supply toner to the developing device 3. In this case, the replenishment toner may be different from the toner that has already entered the developing device 3.

Sequence control diagram of toner deterioration detection in the first embodiment Schematic configuration diagram of a developing device according to the first embodiment 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment. Schematic configuration diagram of an image forming apparatus according to a second embodiment Schematic configuration diagram of a developing device according to the third embodiment Schematic configuration diagram of an image forming apparatus according to a third embodiment Schematic configuration diagram of a developing device according to the fourth embodiment 1 is a schematic configuration diagram of a toner deterioration information detection device according to a first embodiment. Schematic configuration diagram of a toner deterioration information detecting device according to a third embodiment Sequence control diagram of toner deterioration detection in the third exemplary embodiment Sequence control diagram of toner deterioration detection in the fourth embodiment Sequence control diagram of toner deterioration detection in the fifth exemplary embodiment Schematic showing the balance of force when the developing roller and photosensitive drum are in contact Schematic diagram occupying a balance of force when the developing roller and photosensitive drum are not in contact Measurement result of difference between developing roller driving power at contact and developing roller driving power at separation The figure which shows the difference change of developing roller drive power

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photosensitive drum 2 Charger 3 Developing device 8 Developing container 9 Developing roller 10 Elastic roller 11 Restriction blade 22 Conveyance path 51 Developing roller drive motor 52 Motor drive power detection device 53 Detection result recording device 54 Data processing device 55 Data comparison device T Toner

Claims (12)

An image carrier carrying an electrostatic latent image on the surface;
A developing device for containing the one-component developer and supplying the one-component developer to the image carrier to develop the electrostatic latent image;
A developer carrying member provided in the developing device and carrying a one-component developer on the surface;
Drive means for driving at least one of the image carrier and the developer carrier;
In an image forming apparatus comprising:
The image carrier and the developer carrier are configured to be contactable and separable,
Driving load measuring means for measuring the driving load of the driving means when the image carrier and the developer carrier are in contact with each other and when they are apart from each other;
Developer deterioration determining means for determining deterioration of the developer stored in the developing device based on a measurement value by the driving load measuring means;
Further comprising a,
The developer deterioration determining means is
The driving load of the driving means measured by the driving load measuring means when the image carrier and the developer carrier are in contact with each other is separated from the image carrier and the developer carrier. When the absolute value of the difference between the driving load of the driving unit at the time is less than a predetermined threshold, it is determined that the developer has not deteriorated,
An image forming apparatus , wherein the developer is determined to be deteriorated when the absolute value of the difference is equal to or greater than a predetermined threshold value . The developing device includes:
A developer storage chamber for storing the one-component developer;
A developing chamber provided so as to include the developer carrying member and replenished with the developer from the developer containing chamber;
Developer replenishing means for replenishing the developer from the developer containing chamber to the developing chamber when it is determined by the developer deterioration determining means that the developer has deteriorated;
The image forming apparatus according to claim 1, further comprising: The developing device includes:
When the developer deterioration determining means determines that the developer has deteriorated, the developing
The image forming apparatus according to claim 2, further comprising developer discharging means for discharging the developer from the chamber . The image carrier is a rotatable drum type,
A layer thickness regulating member that has elasticity and conductivity and regulates the layer thickness of the developer carried on the developer carrying body by applying a voltage;
A developer supply member that is rotatably provided in the developing device and that supplies a developer to the developer carrier when a voltage is applied;
A transfer means that is rotatably provided to contact the surface of the image carrier and to transfer an image on the image carrier to a recording agent by applying a voltage;
Control that slows the peripheral speed of the image carrier or decreases the absolute value of the voltage applied to the layer thickness regulating member when the developer deterioration determining means determines that the developer has deteriorated Alternatively, the image forming condition is changed by executing at least one of control for decreasing the absolute value of the voltage applied to the developer supply unit and control for increasing the absolute value of the voltage applied to the transfer unit. Image forming condition control means;
The image forming apparatus according to claim 1, further comprising: The developer deterioration determining means is
The driving load of the driving means measured by the driving load measuring means when the image carrier and the developer carrier are in contact with each other is separated from the image carrier and the developer carrier. When the absolute value of the difference between the driving load of the driving unit at the time is less than a predetermined second threshold value smaller than the threshold value, the developer is determined to be normal,
When the absolute value of the difference is greater than or equal to the second threshold and less than the threshold, it is determined that the developer is nearly deteriorated,
The image forming apparatus according to claim 1, wherein the developer is determined to be deteriorated when the absolute value of the difference is equal to or greater than the threshold value . The driving load measuring means includes
The image forming apparatus according to claim 1 , wherein a driving load of the driving unit is measured by detecting a driving power of the driving unit. The driving load measuring means includes
6. The image forming apparatus according to claim 1 , wherein the driving load of the driving unit is measured by detecting a driving current of the driving unit. The driving load measuring means includes
The image forming apparatus according to claim 1 , wherein a driving load of the driving unit is measured by detecting a driving torque of the driving unit. Using the absolute value of the difference in the initial stage of use of the developing device as a reference value,
The image forming apparatus according to claim 1, wherein a value obtained by multiplying the reference value by 1.5 is set as the threshold value . The driving load measuring means includes
The image forming apparatus according to claim 1 , wherein a driving load of the driving unit is measured during non-image formation. The driving load measuring means includes
10. The image forming apparatus according to claim 1 , wherein a driving load of the driving unit is measured at a time between sheets when image formation is continuously performed . The driving load measuring means includes
After the developer is supplied to the electrostatic latent image and the electrostatic latent image is visualized on the surface of the image carrier, the developer carrier is driven in a non-sheet-passing state and then rotated. The image forming apparatus according to claim 1 , wherein a driving load of the driving unit is measured.

Images