JP2009058540A - Developing device in image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developing device in an image forming apparatus, which prevents, with a simple configuration, problems such as an image density decrease resulting from an increase in the amount of charged toner in a low temperature/low humidity environment and toner scatter resulting from insufficient charging in a high temperature/high humidity environment, and is capable of image formation while ensuring high image quality for a long time in wide environmental conditions from high temperature/high humidity to low temperature/low humidity. <P>SOLUTION: An increase in the amount of charged toner in a low temperature/low humidity environment is prevented by using a water container and a stirring belt, thereby humidifying the inside of the developing device efficiently. Insufficient charging in a high temperature/high humidity environment is prevented by composing toner by the use of spherical magnetic powder which is less likely to be discharged. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in an image forming apparatus such as a copying machine, a printer, a facsimile, or a composite machine using an electrophotographic method, and particularly uses a magnetic one-component toner and ranges from high temperature / high humidity to low temperature / low humidity. The present invention relates to a developing device in an image forming apparatus capable of forming an image while maintaining high image quality over a long period of time under a wide range of environmental conditions.

  In an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a composite machine using an electrophotographic method, first, a light source whose surface is uniformly charged with a predetermined polarity and modulated based on predetermined document information The photosensitive member is exposed to light from the light to form an electrostatic latent image. Then, a toner is attached to the electrostatic latent image by a developing device to form a toner image, which is transferred to a predetermined paper, and then conveyed to a fixing device to be heated and pressed to fix the toner image on the paper, thereby forming an image. Is done. The toner remaining on the surface of the photoconductor after the toner image is transferred to a sheet is cleaned with a cleaning blade or the like to remove the remaining toner, and is further neutralized by light irradiation or the like to prepare for the next image formation.

  As a developer used in such an image forming apparatus, there are a one-component developer composed only of toner and a two-component developer composed of toner and carrier. Among these, a developing method using a one-component developer is called, for example, a magnetic one-component jumping method, and a magnetic sleeve is used to carry a magnetic one-component toner on a rotating developer carrier having a magnet disposed therein. There is a system in which the toner layer thickness is regulated by a magnetic blade and the toner is charged to fly to an electrostatic latent image and developed.

  In such a development system, it is important to properly charge the toner in order to form a high-quality image. Generally, it is optimal in an environment of, for example, a temperature of 20 ° C. and a humidity of 60% ± 10%. The design is such that a charge amount can be obtained. However, in such a general environment, for example, in a low temperature and low humidity environment where the temperature is 10 ° C. or less and the humidity is 10%, the toner becomes high in resistance, and a charge-up occurs and the image density is lowered.

  For this reason, for example, in Patent Document 1, in order to prevent the developer from becoming high resistance and lowering the developing ability in image formation under a low humidity environment with a humidity of several percent, water in the toner storage container or water in the water absorbing member is prevented. A technique is disclosed in which water that has been soaked in water is prepared as a water chamber, and naturally evaporated water humidifies the inside of the developing device through the vents, thereby preventing image defects due to a low humidity environment at low temperatures. .

  Further, in Patent Document 2 filed by the applicant of the present application, the technology for preventing the low-humidity environment of Patent Document 1 is to naturally humidify through a vent, and humidity adjustment is performed by natural action. Since there is a problem of delay in time, a humidity sensor and a humidifier with a water atomizing unit are provided so that humidification can be instantaneously performed at low humidity, and mist is removed from the atomizing unit based on humidity information from the humidity sensor. Techniques for generating and humidifying are shown. Further, Patent Document 3 discloses means for humidifying the entire apparatus by providing the image forming apparatus with humidity detection means and humidification means.

JP 59-42567 A JP-A-4-204965 JP-A-4-349473

  However, the low-humidity environment prevention technique at low temperature shown in Patent Document 1 has a problem that sufficient humidity control cannot be performed because the interface of water in the water chamber is small, and the technique of Patent Document 2 Since the humidity is forcibly given as a mist, water droplets adhere to the toner floating in the developing device, and if it adheres to the vicinity of the vent, the toner adheres and the vent is blocked, There is a problem that humidity control becomes unstable over time. Further, the technique of Patent Document 3 is a means for humidifying the entire image forming apparatus even though the developing device is almost sealed except for the developing sleeve, and the humidity control effect on the developing device appears last. Therefore, it is impossible to improve the humidity responsiveness to the inside of the developing device.

  In addition, this was a case of a low temperature / low humidity environment. However, in an area where a high temperature and high humidity environment of 35 ° C. and a humidity of 90% exists on a daily basis, as in Southeast Asia, for example, the discharge from the toner is caused by the humidity. It is easy to occur, and it is difficult to maintain a predetermined charge amount, and thus toner scattering occurs. This is particularly noticeable in toners using magnetic powder, such as octahedral magnetic powder, where an acute angle portion exists and discharge is likely to occur from the acute angle portion.

  Therefore, in the present invention, a simple configuration does not cause problems such as a decrease in image density due to an increase in toner charge amount in a low temperature / low humidity environment, and a toner scattering due to insufficient charging in a high temperature / high humidity environment. An object of the present invention is to provide a developing device in an image forming apparatus capable of forming an image while maintaining high image quality over a long period of time under a wide range of environmental conditions ranging from low to low temperature and low humidity.

  In order to solve the above-mentioned problems, the applicant of the present application has solved the technical problems described in these patent documents by using a belt-like stirring means that is immersed in water on one side and circulates according to the measurement result of the humidity measuring means. Therefore, it was considered to efficiently humidify the inside of the developing device and to prevent the toner charge amount from increasing in a low temperature and low humidity environment. In addition, it was considered to use spherical magnetic powder as the magnetic powder so as not to cause insufficient charging in a high temperature and high humidity environment. As described above, the octahedral magnetic powder has an acute angle portion and discharge is likely to occur from the acute angle portion, but conversely, since the spherical magnetic powder does not have an acute angle portion, discharge is unlikely to occur, and Less likely to be insufficiently charged even in a wet environment.

Therefore, the developing device in the image forming apparatus according to the present invention is
A developer carrying body that has a fixed magnet inside a cylindrical rotating sleeve and faces a photoreceptor on which an electrostatic latent image is formed by an electrophotographic method, and carries the developer to develop the electrostatic latent image; In a developing device in an image forming apparatus, comprising: a stirring unit that stirs the developer and conveys the developer to the developer carrying member, a humidity measuring unit, and a humidifying unit.
The humidifying unit has a belt-like stirring unit that is immersed in water on one side and circulates according to the measurement result of the humidity measuring unit, and is configured to perform humidification into the developing device through an upper vent.
The developer is a magnetic one-component developer, and the blended magnetic powder is a spherical magnetic powder.

  Thus, as the humidifying means, a belt-like stirring means that is immersed in water on one side and circulates according to the measurement result of the humidity measuring means is provided, and when the belt is driven by the measurement result of the humidity measuring means, the belt that has passed through the water is Evaporation of water droplets adhering to the air occurs in the air, whereby the inside of the developing device can be humidified quickly and without flying the water droplets. Therefore, unlike those in Patent Documents 1 to 3, the water interface in the water chamber is small and the humidification effect is small, the responsiveness of humidification to the inside of the developing device is poor, or the toner is vented by moisture for humidification. It is possible to quickly and accurately humidify the inside of the developing apparatus without sticking to the toner, so that it can be prevented by the humidifying means even in an environment where toner in a low temperature / low humidity environment is likely to be charged up, It is possible to prevent a decrease in image density due to an increase in charge amount.

  In addition, spherical magnetic powder is used as the magnetic powder constituting the toner. However, as described above, the spherical magnetic powder does not have an acute angle portion, and is unlikely to discharge, resulting in insufficient charging even in a high temperature / high humidity environment. Few. For this reason, even in areas such as Southeast Asia where the temperature is 35 ° C. and the humidity is 90%, there is no problem that the toner is scattered due to insufficient charging, and in a wide range of environmental conditions for a long period of time. Thus, it is possible to provide a developing device in an image forming apparatus that can form an image while maintaining high image quality.

  The humidifying means has a sponge roller that abuts on the belt portion of the belt-like stirring means and rotates while absorbing the transported water, so that the area where water evaporates increases greatly, and the development is increased accordingly. The inside of the apparatus can be humidified effectively.

  Further, the humidity measuring means is arranged at a position for measuring the humidity of the developer stirred by the developer stirring means, so that the state that must be humidified can be accurately measured.

  According to the present invention, the belt-like stirring unit is driven by the measurement result of the humidity measuring unit, and the inside of the developing device can be humidified quickly and accurately without further water droplets being discharged. Even in an environment where the environmental toner tends to be charged up, it can be prevented by the humidifying means, and a decrease in image density due to an increase in charge amount can be prevented. In addition, since the spherical magnetic powder having no acute angle portion is used as the magnetic powder constituting the toner, discharge is difficult to occur. For example, the temperature is 35 ° C. and the humidity is 90%, as in Southeast Asia. Thus, there can be provided a developing device in an image forming apparatus that does not cause a problem that toner is scattered due to insufficient charging even in a certain region, and can form an image while maintaining high image quality over a long period of time under a wide range of environmental conditions.

  Hereinafter, exemplary embodiments of the present invention will be described in detail 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 unless otherwise specified, but are merely illustrative examples. Not too much.

  FIG. 1 is a schematic cross-sectional view of a developing device in an image forming apparatus according to the present invention. The image forming apparatus provided with the developing device of the present invention shown in FIG. 1 is an image forming apparatus using a magnetic one-component developer. It is. In the figure, reference numeral 10 denotes a photosensitive member that is uniformly charged by a charging device (not shown) and is exposed by an exposure device (not shown) to form an electrostatic latent image. Reference numeral 20 denotes a developing device according to the present invention, and a developing device housing 21 in the developing device 20 has a fixed magnet inside a rotatable cylindrical rotating sleeve so as to face the photoconductor 10 and to store developer. A developer carrying member (developing roller) 22 that carries a magnetic spike and develops an electrostatic latent image, and stirring members 23 and 24 that charge the developer while stirring and convey the developer to the developer carrying member (developing roller) 22. Further, the humidity of the developer stirred by the stirring plate 23 and the stirring members 23 and 24 is measured by separating the stirring members 23 and 24 so that both ends in the axial direction of the stirring members 23 and 24 are not in contact with the developing device casing 21. The humidity sensor 26 is disposed at a position where it can be formed.

  In addition, a toner container 27 is provided above the developing device housing 21 to store the replenishing toner and replenish the toner into the developing device housing 21 by the toner replenishing roller 28. A water container 30 is provided on the opposite side of the photoconductor 10 in the body 21. The water container 30 is a belt-like stirring means that is stretched around a driving roller 31 and a driven roller 32 disposed in the water 35 and is immersed in water on one side and circulates according to the measurement result of the humidity measuring means. The agitation belt 36 is provided with a sponge roller 33 that abuts on the agitation belt 36 and rotates while absorbing the conveyed water, and humidifies the interior of the developing device housing 21. 34 is provided.

  The developing device 20 further includes a humidity sensor 26 when the toner is supplied from the toner container 27 to the developing device casing 21 by the toner replenishing roller 28, and the humidity in the developing device 20 is, for example, 20%. When the following is detected, the stirring belt 36 in the water container 30 is rotated, and the adhering water droplets evaporate when the stirring belt 36 that has passed through the water exits into the air. And humidify the air while improving the response to humidification. Further, during this humidification, the sponge roller 33 that is in contact with the stirring belt 36 at the top absorbs the water carried by the stirring belt 36 and effectively humidifies the inside of the developing device 20 while greatly increasing the water evaporation area. Be able to.

  For this reason, the developing device in the image forming apparatus according to the present invention has a small water interface in the water chamber so that the humidifying effect is small, or the responsiveness of humidification to the inside of the developing device is poor or humidifies, as in the above-mentioned patent document. Therefore, the toner does not block and fix the vent hole due to the moisture, so that the inside of the developing device can be humidified quickly and accurately.

  The image forming apparatus having the developing device according to the present invention configured as described above, when starting the image formation as described above, for example, drives the stirring belt 36 in the water container 30 for 10 seconds to perform stirring and humidify. Then, an image forming operation is performed. In this image forming operation, as described above, first, the surface of the photoconductor 10 is uniformly charged with a predetermined polarity, and the surface of the photoconductor 10 is irradiated with light from a light source (not shown) modulated based on predetermined document information. Exposure to form an electrostatic latent image. Then, the toner is attached to the electrostatic latent image by the magnetic spikes by the one-component developer carried by the developer carrying member (developing roller) 22 in the developing device 20 described above, and the toner image is applied to a predetermined sheet. After the transfer, the toner image is fixed on the paper by a fixing device (not shown). The toner remaining on the surface of the photoconductor 10 after the toner image is transferred to the paper is also cleaned by a cleaning blade (not shown) to remove the remaining toner, and is further discharged by light irradiation or the like. For image formation.

  The toner constituting the developer used in this developing device is prepared by dispersing various toner compounding agents such as a colorant in a binder resin. The type of the binder resin is not particularly limited, but for example, styrene resin, acrylic resin, styrene-acrylic copolymer, polyethylene resin, polypropylene resin, vinyl chloride resin, polyester resin, It is preferable to use thermoplastic resins such as polyamide resins, polyurethane resins, polyvinyl alcohol resins, vinyl ether resins, N-vinyl resins, styrene-butadiene resins.

  The glass transition point (Tg) of the binder resin is preferably 50 to 70 ° C. When the glass transition point is lower than the above range, the obtained toners are fused and stored in the developing device. Stability is reduced. Further, since the resin strength is low, there is a tendency that toner adheres to the photoreceptor. On the other hand, if the glass transition point is higher than the above range, the toner fixing property is lowered. In addition, the glass transition point of binder resin can be calculated | required from the change point of specific heat using a differential scanning calorimeter (DSC).

  The colorant is not particularly limited, and the charge control agent remarkably improves the charge level and the charge rising property (an index indicating whether the charge is charged to a constant charge level in a short time), and is durable and stable. It is blended in order to obtain excellent characteristics and the like. That is, when the toner is positively charged and used for development, a positively chargeable charge control agent can be added. When the toner is negatively charged and used for development, a negatively chargeable charge control agent can be added. Further, the positively or negatively chargeable charge control agent is preferably contained in the toner in an amount of 1.0 to 7.0 parts by mass when the total amount of toner is 100 parts by mass.

  If the addition amount of the charge control agent is smaller than the above range, it tends to be difficult to stably charge the toner to a predetermined polarity, and the electrostatic latent image is developed using the toner to develop an image. When forming, the image density tends to decrease or the durability of the image density decreases. Further, the charge control agent tends to be poorly dispersed, so that there is a tendency to cause so-called fogging, and the photoreceptor contamination becomes severe. On the other hand, if the charge control agent is used in a larger amount than the above range, the image tends to be defective due to environmental resistance, particularly charging failure under high temperature and high humidity, and defects such as photoconductor contamination tend to occur.

  The waxes used for improving the fixing property and the offset property are not particularly limited, but are generally blended in an amount of 1 to 5 parts by mass when the total amount of toner is 100 parts by mass. Preferably it is. If the addition amount of the wax is less than 1 part by mass, there is a tendency that the offset property and image smearing cannot be effectively prevented. Tend to decrease.

  And magnetic powder is mix | blended in binder resin and it is set as 1 component developing agent. Examples of such magnetic powder include those known per se, such as iron, cobalt, nickel and other ferromagnetic metals such as ferrite and magnetite, alloys or compounds containing these elements, or ferromagnetic materials. An alloy that does not contain an element but becomes ferromagnetic when subjected to an appropriate heat treatment, chromium dioxide, or the like can be given.

  These magnetic powders are spherical fine powders having an average particle diameter of 0.1 to 1 μm, particularly 0.1 to 0.5 μm, and are uniformly dispersed in the above-described binder resin. The magnetic powder can also be used after being subjected to a surface treatment with a surface treatment agent such as a titanium coupling agent or a silane coupling agent. It is desirable that the shape is spherical, and in the octahedral magnetic powder or the like that is generally used, charge leakage sites are generated on the toner surface, and charge leakage occurs excessively under high temperature and high humidity.

  The magnetic powder is preferably contained in the toner in an amount of 30 to 60 parts by mass, particularly 40 to 50 parts by mass. When the magnetic powder is used in a larger amount than the above range, the durability of the image density is deteriorated, and the fixability tends to be extremely lowered. When the amount is smaller than the above range, the fog in the image density durability is deteriorated. End up.

  The toner used in the present invention is prepared by mixing the above-described binder resin and various toner compounding agents such as a charge control agent, melt-kneading using a kneader such as an extruder, and then cooling, pulverizing and classifying the mixture. Is obtained. Further, such a toner is externally added with fine particles such as colloidal silica, hydrophobic silica, alumina, and titanium oxide (usually having an average particle size of 1.0 μm or less), and is formed on the surface of the photoreceptor alone as a one-component developer. Used to develop the electrostatic latent image.

  The fine particle external additive is used for improving fluidity, storage stability, cleaning properties, etc. by surface treatment of the toner. Usually, when the total amount of the toner is 100 parts by mass, Used in an amount of 0.2-10.0 parts by weight. The external addition of these fine particles is performed by stirring and mixing with the toner in a dry manner. This stirring and mixing is performed using a Henschel mixer or a Nauter mixer so that the fine particles are not embedded in the toner. Good.

  2 and 3 use the developing device in the image forming apparatus according to the present invention shown in FIG. 1, and the temperature is 5 ° C. and the humidity is 10%, the low temperature / low humidity environment (FIG. 2), the temperature is 35 ° C., and the humidity is 90%. In a high-temperature and high-humidity environment (FIG. 3), when the toner described above is used and 200,000 images are formed while changing the conditions, such as when the water container 30 is driven or when the water container 30 is not used. 6 is a table showing the results of examining the change in humidity, the change in charge amount of toner, and the change in density of the formed image in the developing device 20.

As the image forming apparatus used for this investigation, an image forming apparatus modified so that a water container can be installed in the printer LS-1800 manufactured by Kyocera Mita was used. The used toner was prepared by first producing a styrene acrylic resin as a binder resin as follows. In a reactor equipped with a thermometer, a stirrer and a nitrogen introduction tube, 300 parts of xylene were placed, and under a nitrogen stream, a mixed monomer of 845 parts of styrene and 155 parts of n-butyl acrylate, and di-tert-butyl peroxide (Polymerization initiator) It was dripped over 3 hours at 170 degreeC using the mixed solution of 8.5 parts and 125 parts of xylene. After the dropping, the reaction was carried out at 170 ° C. for 1 hour to complete the polymerization. Thereafter, the solvent was removed to obtain a binder resin. As the magnetic powder, magnetic powder made of magnetite that is Fe ₃ O ₄ (FeO · Fe ₂ O ₃ ), having a spherical particle shape and an average particle diameter of 0.20 μm was used.

  The toner comprises 60 parts by mass of the binder resin thus produced, 40 parts by mass of the above spherical magnetic powder, 5 parts by mass of wax (H1 manufactured by Sasol), 3 parts by mass of CCA (N-10 manufactured by Orient Chemical Industries). The parts were mixed, melt kneaded with a twin screw extruder, cooled and coarsely pulverized with a hammer mill. Thereafter, the finely pulverized product by a mechanical pulverizer was classified by an airflow classifier to obtain a toner having a volume average particle size of 8.0 μm. Then, 0.5 parts by mass of silica (RA-200H manufactured by Nippon Aerosil Co., Ltd.) was externally added to the obtained toner powder with a Henschel mixer, and adhered to the surface of the toner powder to prepare a toner.

(Evaluation Example 1)
The toner is filled in the toner replenishing container 27 to obtain a replenishing toner. Evaluation Example 1 uses the toner prepared as described above, and when the developing device 20 is in operation and when toner is replenished from the toner container 27, stirring is performed by the stirring belt 36 in the water container 30 for 10 seconds. In addition, when the humidity detection result of the humidity sensor was 20% or less, the stirring belt 36 was further continuously operated.

(Evaluation Example 2)
Evaluation Example 2 uses the same toner as the conditions in Evaluation Example 1 described above, and it is the same that the stirring by the stirring belt 36 in the water container 30 is performed for 10 seconds when the developing device 20 is in operation. Even when the humidity detection result of 26 is 20% or less, the stirring belt 36 was evaluated without being continuously operated.

(Comparative Example 1)
In Comparative Example 1, the same toner as the conditions in Evaluation Example 1 was used but the water container 30 was not installed.
(Comparative Example 2)
In Comparative Example 2, among the conditions in Evaluation Example 1, the magnetic powder constituting the toner is octahedral magnetic powder, and when the developing device 20 is operated and when toner is supplied from the toner container 27, Stirring by the stirring belt 36 was performed for 10 seconds, and when the humidity detection result of the humidity sensor was 20% or less, the stirring belt 36 was further continuously operated.
(Comparative Example 3)
The comparative example 3 was implemented without installing the water container 30 in the comparative example 2.

  In the evaluation, when the water container 30 is installed and the evaluation is performed in a low temperature / low humidity environment, the image forming apparatus is left in the same low temperature / low humidity environment as the evaluation for 3 days, and the experiment is performed after the humidity is adjusted. Started. Among the evaluation items, the toner charge amount was measured by using a charge amount measuring device (Q / M Meter 210HS) manufactured by TREK. The image characteristics are as follows: image evaluation pattern by the page printer at the initial stage in a low temperature / low humidity environment (FIG. 2) with a temperature of 5 ° C. and a humidity of 10% (FIG. 2) and a high temperature / high humidity environment (FIG. 3) Was printed as an initial image, and then 200,000 sheets were continuously fed, and an image evaluation pattern was printed again every 100,000 sheets to obtain a post-endurance image. Each image evaluation pattern was obtained by measuring a solid image using a Macbeth reflection densitometer (RD914), measuring the density of 9 points in a certain solid portion, and calculating the average value (ID). The image density was 1.10 or higher.

  First, in the case of a low-temperature and low-humidity environment having a temperature of 5 ° C. and a humidity of 10% shown in FIG. 2, the water container 30 is installed, the toner prepared as described above is used, and the developing device 20 is in operation. When the toner was replenished from the toner container 27, the stirring by the stirring belt 36 in the water container 30 was performed for 10 seconds. When the humidity detection result of the humidity sensor was 20% or less, the stirring belt 36 was further continuously operated. Evaluation Example 1 and toner are the same as those in Evaluation Example 1, and it is the same that the stirring by the stirring belt 36 in the water container 30 is performed for 10 seconds when the developing device 20 is in operation, but the humidity detection result of the humidity sensor 26 is 20%. Evaluation Example 2 evaluated without performing continuous operation of the agitation belt 36 even in the following cases, the magnetic powder constituting the toner is octahedral magnetic powder, and the developing device 20 is in operation, When the toner is replenished from the tena 27, the stirring by the stirring belt 36 in the water container 30 is performed for 10 seconds, and when the humidity detection result of the humidity sensor is 20% or less, the stirring belt 36 is continuously operated. In Example 2, both the image density and the charge amount were not significantly changed from the initial time, and the humidity was 28 to 36% and good.

  On the other hand, the same toner as used in Evaluation Example 1 was used, but Comparative Example 1, which was carried out without installing the water container 30, had a high charge amount from the beginning and a low image density at the same time. This is considered to be a result of the toner being charged up because the water container 30 was not installed and the humidity remained low. In Comparative Example 3, which was carried out without installing the water container 30 in Comparative Example 2, the image density was lower and the charge amount was higher than in the initial stage, and this became more prominent as the number of images formed increased.

  Next, FIG. 3 shows a case of a high temperature and high humidity environment with a temperature of 35 ° C. and a humidity of 90%. In this case as well, the evaluation example 1 and the evaluation example 2 in which the water container 30 is installed are such a high temperature.・ No problem occurred even in a high humidity environment.

  On the other hand, the same toner as in evaluation example 1 was used. However, in Comparative example 1 which was carried out without installing the water container 30, it was not carried out because charge-up occurred in a low temperature / low humidity environment. In Comparative Example 2 in which the water container 30 was installed using octahedral magnetic powder as the magnetic powder to be processed, and in Comparative Example 2 in which the water container 30 was not installed in Comparative Example 2, the charge amount decreased at the stage of 100,000 sheets. As a result, the image density was lowered, and the toner density was further reduced at 200,000 sheets. This is presumably because the discharge progressed in a high humidity environment because octahedral magnetic powder was used.

  In this way, toner is formed using spherical magnetic powder and a water container 30 is provided to prevent charge-up by performing humidification in a low temperature / low humidity environment, and spherical magnetic powder for a high temperature / high humidity environment. By preventing the decrease in charge by utilizing the characteristics of the battery that are difficult to discharge, toner scattering due to insufficient charging will not occur even in high-temperature and high-humidity environments, and images resulting from increased toner charge in low-temperature and low-humidity environments. It is possible to provide a developing device in an image forming apparatus capable of forming an image while maintaining high image quality over a long period of time without causing a decrease in density.

  According to the present invention, it is possible to perform image formation with high image quality in both low temperature / low humidity environment and high temperature / high humidity environment, and in Southeast Asia where the temperature is 35 ° C. and the humidity is 90% on a daily basis. It is possible to provide an image forming apparatus capable of forming an image with the same image quality.

1 is a schematic cross-sectional view of a developing device in an image forming apparatus according to the present invention. Using Example 1 of the developing device in the image forming apparatus according to the present invention, the image density and the toner density when forming 200,000 sheets of images while changing the conditions in a low-temperature and low-humidity environment at a temperature of 5 ° C. and a humidity of 10%. It is a table | surface which shows the result of having investigated the charge amount. Image density and toner when 200,000 sheets of images were formed using Example 1 of the developing device in the image forming apparatus according to the present invention and changing conditions in a high temperature / high humidity environment of 35 ° C. and 90% humidity It is a table | surface which shows the result of having investigated the charge amount of.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Photoconductor 20 Developing device 21 Developing device housing 22 Developer carrier (developing roller)
23 Stirring member 24 Stirring member 25 Partition plate 26 Humidity sensor 27 Toner container 28 Toner supply roller 30 Water container 31 Drive roller 32 Followed roller 33 Sponge roller 34 Vent 35 Water 36 Stirring belt

Claims (3)

A developer carrying body that has a fixed magnet inside a cylindrical rotating sleeve and faces a photoreceptor on which an electrostatic latent image is formed by an electrophotographic method, and carries the developer to develop the electrostatic latent image; In a developing device in an image forming apparatus, comprising: a stirring unit that stirs the developer and conveys the developer to the developer carrying member, a humidity measuring unit, and a humidifying unit.
The humidifying unit has a belt-like stirring unit that is immersed in water on one side and circulates according to the measurement result of the humidity measuring unit, and is configured to perform humidification into the developing device through an upper vent.
The developing device in an image forming apparatus, wherein the developer is a magnetic one-component developer, and the blended magnetic powder is a spherical magnetic powder.   2. The developing in an image forming apparatus according to claim 1, wherein the humidifying means has a sponge roller that contacts the belt portion of the belt-like stirring means and rotates while absorbing the conveyed water. apparatus.   3. The developing device in an image forming apparatus according to claim 1, wherein the humidity measuring unit is disposed at a position for measuring the humidity of the developer stirred by the developer stirring unit.

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