JP5263675B2 - Developer supply device, development device, and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a developer supply device, a developing device, and an image forming apparatus that achieve the application of charges to one-component developer and the supply of charged developer to a developer carrier while minimizing stress on the developer, and that suppresse attaching of weakly charged developer to the developer carrier. <P>SOLUTION: The developer supply device includes: a developer supply roller 31 disposed opposite a developing roller 22 with a space left therefrom and used for conveying toner T to an area opposite the developing roller 22; and a suction pump 61, being a suction means, which sucks air through a suction hole 31a formed in the developer supply roller 31 and causes the toner T to adhere to the surface of the developer supply roller 31. In addition, the developer supply device includes a charge applying means having a charge emitting member 25 that applies charges to toner T without touching the toner during or before the passage of it through the area opposite the developing roller 22, and a mesh electrode 29 that is a counter electrode of the charge member 25. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention includes a developer supply device that supplies a developer to a developer carrier of a one-component developing device provided in an image forming apparatus such as a printer, a facsimile machine, and a copier, a one-component developing device, and the like. The present invention relates to an image forming apparatus.

As a conventional one-component developing device, there is one provided with a roller-like developer supply roller as developer supply means for supplying a developer to a developer carrier for developing a latent image on the latent image carrier. FIG. 6 shows an example of a conventional one-component developing device. A developing device 10 shown in FIG. 6 includes a developer supply roller 412 that is a roller-shaped developer supply member that supplies a developer to a developing roller 22 that is a developer carrier opposite to a photoreceptor 21 that is a latent image carrier. Is provided. As such a developer supply roller, a roller made of a foamable material having flexibility, that is, a so-called sponge roller is used.
FIG. 7 is a schematic diagram showing how the developer is transferred from the developer supply roller 412 to the developing roller 22 of the developing device 10 shown in FIG. As shown in FIG. 7, the developer supply roller 412 is brought into contact with the developing roller 22 through the toner T that is a one-component developer. As a result, the toner T carried by the developer supply roller 412 can be adhered to the developing roller 22 while being frictionally charged. As a result, charging of the toner T and supply of the toner T to the developing roller 22 can be performed.
When the toner T is supplied to the developing roller 22 as described above, a strong stress is applied to the toner T, so that the toner formed of resin is easily deteriorated. More specifically, an additive such as silica and titanium called fluidized particles attached around the toner base is buried in the toner resin, and the fluidity is lowered by the filling, so that the toner is transferred to the developing roller 22. T tends to adhere. Further, the toner T may be dissolved by applying frictional heat. When the toner T is dissolved, a so-called filming to the developing roller 22 occurs. In the configuration in which the toner T is charged by frictional charging with the developing roller 22, the surface of the developing roller 22 is covered with the resin of the toner T, so that the toner T is in the same state as the frictional charging between the toners T. As a result, the charged state of the toner T is in a state where a predetermined polarity and charge amount cannot be obtained, and background stains are liable to occur, and the development amount is reduced and the image quality is lowered.
In recent years, from the viewpoint of reducing energy consumption of the image forming apparatus due to environmental problems, the melting temperature of the toner has been lowered particularly in order to reduce energy consumed for fixing. When the melting temperature of the toner T is low, the toner T is easily dissolved by frictional heat at the time of supply to the developing roller 22, and filming to the developing roller 22 is likely to occur. Further, in order to improve the releasability of the toner with respect to the fixing member at the time of fixing, many conventional methods of mixing and adding a wax material into the toner from oil application to the fixing member have been performed. Such wax also causes the toner T to easily adhere to the developing roller 22 when the toner T is dissolved, and causes filming. Together, these points are further accelerating factors for the above-mentioned problems such as background contamination and degradation of image quality.

As a configuration capable of preventing the occurrence of problems caused by contacting the developer supply member as described above in a state of rubbing against the developer carrier via the developer, there is a developing device described in Patent Document 1. .
In the developing device described in Patent Document 1, a developer supply member is provided so as to be close to the developing roller and has a conductive wire-like member. In this wire-like member, a voltage is applied so that a potential difference between the wire-like member and the developer carrier is equal to or higher than a discharge start voltage, and a current having the same polarity as the developer charging polarity flows from the wire-like member to the developing roller. Yes. In the developing device of Patent Document 1, the toner in the vicinity of the wire member is charged by the discharge, the toner charged by the current from the wire member to the developing roller is directed to the developing roller, and the charged toner is supplied onto the developing roller. . With such a configuration, it is not necessary to rub the developer for charging the developer and supplying the developer to the developing roller. Therefore, as in the conventional developing device described with reference to FIGS. 6 and 7, it is possible to prevent the occurrence of problems caused by bringing the developer supply roller into contact with the developing roller in a state of rubbing against the developing roller via the developer. .

  However, in the developing device of Patent Document 1, the surface of the developing roller passes through the developer reservoir portion on the upstream side of the developing roller in the surface movement direction from the position where the developing roller and the wire-shaped member are close to each other. Then, the developer is transported to a position where the wire-like member and the developing roller are close to each other as the developer moves along the surface of the developing roller. Therefore, when the surface of the developing roller passes through the developer reservoir, the developer staying in the reservoir is brought into contact with the surface of the developing roller without being moved along with the surface movement of the developing roller. Therefore, the developing roller applies stress to the developer that is not carried or conveyed by the developing roller.

Therefore, the present applicant has proposed the following developing device in Japanese Patent Application No. 2008-205124. That is, an airflow discharge member that is disposed below the development roller so as to have a gap between the development roller and that has a plurality of openings for discharging an airflow, and is disposed below the airflow discharge member, and has a negative polarity. A charge discharging member that discharges charges. The airflow discharge member can pass electric charges. In addition, a potential difference is provided between the developing roller and the charge discharging member so that the charge discharging member has a higher negative potential than the developing roller. The developing device is provided with an air pump that discharges airflow upward from the opening of the airflow discharge member. With this configuration, the developer supplied between the airflow discharge member and the developing roller is disturbed and fluidized by the airflow released upward from the opening of the airflow discharge member. In addition, since the negative charge potential of the charge discharging member is higher than that of the developing roller, the negative charge discharged from the charge discharging member is applied to the upper developing roller by the potential difference between the developing roller and the charge discharging member. Move towards. Above the charge releasing member and below the developing roller, there is an airflow releasing member through which charges can pass, and above that there is a developer fluidized by the airflow discharged upward from the opening. For this reason, the upward charge discharged from the charge release member collides with the developer particles and charges the developer. The charged developer moves toward the developing roller due to a potential difference between the charge releasing member and the developing roller, and is carried on the developing roller, whereby the developer is supplied to the developing roller.
At this time, if the volume of the developer fluidized between the developing roller and the airflow discharge portion is large enough not to contact the developing roller, the developing roller does not contact the developer that is not carried or conveyed by the developing roller. Therefore, stress from the developing roller is not applied to the developer that is not carried or conveyed by the developing roller. Further, even when the volume of the developer is such that it contacts the developing roller, the fluidized developer is easy to move. For this reason, the developer roller does not carry or carry the developer roller compared to the conventional construction in which the developer roller rubs against the developer that is not carried or transported, but the developer roller contacts the developer that stays. Stress can be sufficiently reduced.

  However, in the developing device proposed in Japanese Patent Application No. 2008-205124, the following problems remain. That is, the developer supplied between the airflow releasing member and the developing roller approaches the developing roller by the airflow released from the opening of the airflow releasing member. At this time, there is a possibility that toner that is not sufficiently charged may electrostatically adhere to the developing roller. As a result, this is a problem that causes soiling and the like.

  The present invention has been made in view of the above problems, and its purpose is to provide the developer with charge imparting to the one-component developer and supply of the developer imparted with charge to the developer carrier. It is an object to provide a developer supply device, a developing device, and an image forming apparatus that can be performed with low stress and can suppress adhesion of a weakly charged developer to a developer carrying member.

In order to achieve the above object, the invention of claim 1 is to develop a latent image by carrying a one-component developer on a surface that moves and supplying the one-component developer to the latent image on the latent image carrier. In the developer supply device for supplying the one-component developer to the developer-carrying member that is disposed opposite to the developer-carrying member, the one-component developer is held on the surface. The surface of the developer transport member moves endlessly and transports the one-component developer to a region facing the developer carrier, and air is sucked from a suction hole formed in the developer transport member. A suction unit that adsorbs the one-component developer on the surface of the developer conveying member, and the one-component developer before the one-component developer on the surface of the developer conveying member passes through the exit of the area facing the developer carrying member. Charge imparting means for imparting charge to the one-component developer in a non-contact manner with the developer The is characterized in that it comprises.
According to a second aspect of the present invention, in the developer supply apparatus according to the first aspect, a potential difference is formed between the developer conveying member and the developer carrying member in the facing region, and the development is performed in the facing region. The one-component developer on the surface of the agent conveying member is electrostatically adhered to the surface of the developer carrying member.
According to a third aspect of the present invention, there is provided the developer supply apparatus according to the second aspect, wherein the developer conveying member has a hollow portion and includes a plurality of suction holes communicating the surface and the hollow portion. The charge applying means includes at least a charge releasing member that discharges charges, and the charge releasing member is disposed in a hollow portion of the developer conveying member so as to face the developer carrying member. It is characterized by that.
According to a fourth aspect of the present invention, in the developer supply apparatus according to the third aspect, the charge applying unit includes a counter electrode facing the charge discharging member, and the counter electrode is connected to the developer carrying member and the developer carrier. It is arranged between the developer conveying member.
According to a fifth aspect of the present invention, in the developer supply device according to the third or fourth aspect, a dischargeable wire charger is used as the charge discharging member.
According to a sixth aspect of the present invention, in the developer supply device according to any of the third to fifth aspects, the diameter of the suction hole is made smaller than the diameter of the one-component developer.
According to a seventh aspect of the present invention, in the developer supply apparatus according to any one of the first to sixth aspects, the developer conveying member is disposed below the developer conveying member so as to be spaced from the developer conveying member. An airflow discharge unit that discharges an airflow toward the surface, and a developer transfer unit that transfers the one-component developer between the developer transport member and the airflow discharge unit are provided.
The invention of claim 8 is characterized in that, in the developer supply apparatus of claim 7, a developer pump is used as the developer transfer means.
The invention according to claim 9 further comprises a developer carrying member carrying a one-component developer, and a developer supplying means for supplying the developer to the developer carrying member. A developing device for developing a latent image by supplying a developer to a latent image on a latent image carrier, comprising the developer supplying device according to any one of claims 1 to 8 as the developer supplying means. Is.
According to the tenth aspect of the present invention, the developing unit develops the latent image by attaching a one-component developer to the latent image on the latent image carrier, and the resulting toner image is finally recorded on the recording material. In the image forming apparatus that performs image formation by transferring to the above, the developing device according to claim 9 is used as the developing means.

According to the present invention, the one-component developer is adsorbed on the surface of the developer transport member by sucking air from the suction hole formed in the developer transport member by the suction means. A certain developer can be adhered to the surface of the developer conveying member. In this way, a developer that is not in contact with the developer conveying member can be adhered to the surface of the developer conveying member, so that the developer conveying member and the developer are not brought into contact with each other on the surface of the developer conveying member. Developer can be deposited. Therefore, it is possible to prevent the developer conveying member from contacting the developer that is not held or conveyed by the developer conveying member, and the developer conveying member applies stress to the developer that is not held or conveyed by the developer conveying member. It becomes possible to suppress.
Further, even when the developer is adsorbed to the developer transport member by electrostatic force, a developer that is not in contact with the developer transport member can be adhered to the surface of the developer transport member. However. In this case, it is necessary to triboelectrically charge the developer before the developer is electrostatically adsorbed to the developer conveying member, and stress is applied to the developer. On the other hand, in the present invention, the developer is adsorbed on the developer conveying member by the air suction force, so that it is not necessary to triboelectrically charge the developer before adsorbing the developer on the developer conveying member. Therefore, the stress applied to the developer can be reduced as compared with the case where the electrostatic force is attracted to the developer transport member.
Further, before the one-component developer on the surface of the developer conveying member passes through the exit of the area facing the developer carrier, the developer is charged by applying a charge to the one-component developer by the charge applying unit. . Since the charge imparting means imparts a charge to the developer in a non-contact manner with the developer, stress applied to the developer can be reduced as compared with the one that imparts a charge by contacting the developer.
The charged developer is electrostatically moved to the developer carrier by the potential difference between the developer carrier and the developer transport member in the above-mentioned facing region, and the one-component developer on the developer transport member is developed. It is supplied to the agent carrier. At this time, if the volume of the developer adsorbed on the developer conveying member is such that it does not contact the developer carrying body, the developer carrying body does not contact the developer that is not carried or conveyed by the developer carrying body. . Therefore, the developer carrier does not apply stress to the developer that is not carried or conveyed by the developer carrier. Further, the weakly charged developer whose electrostatic attraction is weaker than the suction force of the suction means does not move to the developer carrier and remains adsorbed on the developer transport member. Therefore, only a sufficiently charged developer adheres to the developer carrying member, and deterioration of image quality such as background stains can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration diagram of a developing device according to a first embodiment; FIG. 3A is a cross-sectional view in the vicinity of a developing roller of the developing device; FIG. 1 is a schematic configuration diagram of a printer according to an embodiment. 6 is a graph comparing the charge amount distribution of the developer before charging and after charging by the developer supply device of Example 1; The graph which compared the additive burial rank of the developer with this invention and the conventional development apparatus. FIG. 2 is a schematic configuration diagram of a developing device according to a second embodiment, (a) is a cross-sectional view in the vicinity of a developing roller of the developing device, and (b) is a schematic diagram of a developer supply device in a cross section indicated by a broken line α in (a). 1 is a schematic configuration diagram of an example of a conventional one-component developing device. FIG. 7 is a schematic diagram showing how a developer is delivered to a developing roller of the developing device of FIG. 6. FIG. 7 is a schematic diagram showing a state in which the layer thickness of the toner T on the developing roller 22 of the developing device shown in FIG. 6 is regulated.

Hereinafter, an embodiment in which the present invention is applied to an electrophotographic printer (hereinafter simply referred to as a printer 100) as an image forming apparatus will be described.
FIG. 2 is a schematic configuration diagram of the printer 100 according to the embodiment.
The printer 100 forms a tandem image forming unit by arranging four image forming units of yellow, cyan, magenta, and black obliquely. In the tandem image forming unit, toner image forming units 20Y, 20C, 20M, and 20K as individual image image forming units are sequentially arranged from the upper left in the drawing. Here, the suffixes Y, C, M, and K of the respective symbols indicate members for yellow, magenta, cyan, and black, respectively. In the tandem image forming unit, the individual toner image forming units 20Y, 20C, 20M, and 20K are arranged around the drum-shaped photoconductors 21Y, 21C, 21M, and 21K as latent image carriers, respectively. C, M, K, developing devices 10Y, C, M, K, photoconductor cleaning devices 18Y, C, M, K, and the like are provided.

  Further, an optical writing unit 9 as a latent image forming unit is provided below the tandem image forming unit. The optical writing unit 9 includes a light source, a polygon mirror, an f-θ lens, a reflection mirror, and the like, and is configured to irradiate the surface of each photoconductor 21 with laser light based on image data. .

  Further, an endless belt-like intermediate transfer belt 1 is provided as an intermediate transfer member along a tandem image forming portion arranged obliquely. The intermediate transfer belt 1 is wound around support rollers 1a, 1b, and 1c, and a drive motor (not shown) serving as a drive source is connected to a rotation shaft of the drive roller 1a among the support rollers. When this drive motor is driven, the intermediate transfer belt 1 rotates in the counterclockwise direction in the figure and the followable support rollers 1b and 1c rotate. Inside the intermediate transfer belt 1, primary transfer rollers 11 Y, 11 C, 11 M, and 11 C serving as primary transfer devices for transferring toner images formed on the photoreceptors 21 Y, C, M, and K onto the intermediate transfer belt 1. K is provided. The primary transfer rollers 11Y, 11C, 11M, and 11K sandwich the intermediate transfer belt 1 between the photoreceptors 21Y, 21C, 21M, and 21K, and form primary transfer nips.

  Further, a secondary transfer roller 5 as a secondary transfer device is provided downstream of the primary transfer rollers 11Y, 11C, 11M, and 11K in the driving direction of the intermediate transfer belt 1. A support roller 1b is disposed on the opposite side of the secondary transfer roller 5 and the intermediate transfer belt 1, and functions as a secondary transfer counter roller. The support roller 1b and the secondary transfer roller 5 The intermediate transfer belt 1 is sandwiched between the two to form a secondary transfer nip. Also provided are a paper feed cassette 8, a paper feed roller 7, a registration roller 6 and the like for storing a transfer P as a recording medium. Further, on the downstream side of the secondary transfer nip with respect to the traveling direction of the transfer paper P onto which the toner image has been transferred from the intermediate transfer belt 1 at the secondary transfer nip, a fixing device 4 for fixing the image on the transfer paper P, paper discharge A roller 3 is provided.

  Next, the operation of the printer 100 will be described. The photoreceptors 21Y, C, M, and K are rotated by the individual toner image forming units 20Y, 20C, 20M, and 20K, and the charging devices 17Y, 17C, 17M, and 17K are first rotated along with the rotation of the photoreceptors 21Y, 21C, 21M, and 21K. K uniformly charges the surfaces of the photoconductors 21Y, 21C, 21M, and 21K. Next, image data is irradiated with writing light by a laser from the optical writing unit 9 to form an electrostatic latent image on the photoreceptors 21Y, 21C, 21M, 21K. Thereafter, toner is attached by developing devices 10Y, 10C, 10M, and 10K, and the electrostatic latent images are visualized to form yellow, cyan, magenta, and black on each of the photoreceptors 21Y, 21C, 21M, and 21K. A monochromatic image is formed. Further, the drive roller 1a is driven to rotate by a drive motor (not shown), the other driven rollers 1b and 1c and the secondary transfer roller 5 are driven to rotate, the intermediate transfer belt 1 is driven to rotate, and the visible image is transferred to each of the visible images. The images are sequentially transferred onto the intermediate transfer belt 1 at the primary transfer nip. As a result, a composite color image is formed on the intermediate transfer belt 1. The surface of the photoconductors 21Y, 21C, 21M, and 21K after image transfer is cleaned by removing residual toner with photoconductor cleaning devices 18Y, 18C, 18M, and 18K, and preparing for image formation again.

  In accordance with the timing of image formation, the transfer paper P is fed out from the paper feed cassette 8 by the paper feed roller 7 and conveyed to the registration roller 6 and temporarily stops. Then, the sheet is conveyed to the secondary transfer nip while taking timing with the image forming operation. In the secondary transfer nip, the transfer paper P is sandwiched between the intermediate transfer belt 1 and the secondary transfer roller 5, and the toner image on the intermediate transfer belt 1 is secondarily transferred onto the transfer paper P.

  The transfer paper P after the image transfer is sent to the fixing device 4, the heat and pressure are applied by the fixing device 4 to fix the transferred image, and the paper is discharged out of the apparatus by the paper discharge roller 3. On the other hand, the intermediate transfer belt 1 after the image transfer is removed by the intermediate transfer body cleaning device 12 to remove residual toner remaining on the intermediate transfer belt 1 after the image transfer, so that the tandem image forming unit prepares for another image formation.

  The toner image forming portions 20Y, 20C, 20M, and 20K for the respective colors described above are integrally formed and are detachable process cartridges that can be attached to and detached from the main body. These integral process cartridges can be pulled out to the front side of the printer main body along a guide rail (not shown) fixed to the printer 100 main body. Further, the toner image forming unit can be loaded at a predetermined position by pushing the process cartridge into the back side of the printer 100 main body.

Next, a configuration that supplies toner T as a one-component developer to the developing roller 22 that is a developer carrying member of the developing devices 10Y, 10C, 10M, and 10K, which is a characteristic part of the present embodiment, will be described.
The four toner image forming portions 20Y, 20C, 20M, and 20K have the same configuration and operation. Accordingly, the developing device 10 will be described below with the subscripts Y, C, M, and K being omitted.

[Example 1]
Hereinafter, a first embodiment (hereinafter, referred to as a first embodiment) of the developing device 10 having a developer supply device having a feature of the present invention will be described.
FIG. 1 is a schematic configuration diagram of a developing device 10 according to the first embodiment. 1A is a cross-sectional view in the vicinity of the developing roller 22 of the developing device 10 on a surface orthogonal to the rotation axis of the developing roller 22, and FIG. 1B is a cross-sectional view indicated by a broken line α in FIG. 2 is a schematic diagram of a developer supply device 30 provided in the developing device 10. FIG.

A developer supply device 30 as developer supply means shown in FIG. 1 carries a toner T on a surface that moves on the surface, and supplies the toner T to a latent image on the photosensitive member 21 to develop the latent image. The toner T is supplied to the developing roller 22.
The developer supply device 30 according to the first exemplary embodiment includes a developer supply roller 31 that is a developer conveying member that is disposed so as to be spaced from the developing roller 22. Also, an airflow dispersion member 24a that is disposed below the developer supply roller 31 so as to have a space between the developer supply roller 31 and allows airflow to pass from below to above, and upward from the airflow dispersion member 24a. An airflow discharge unit 24 that is an airflow discharge unit including an air pump 60 that discharges air as an airflow is provided. Further, an agitator 28 as a developer transfer member for transferring the toner T in the hopper 14 as a developer storage portion for storing the toner T between the developer supply roller 31 and the airflow dispersion member 24 a is disposed in the hopper 14. Has been. Note that the developer transfer member is not limited to the agitator 28, and any developer may be used as long as the toner T, which is a one-component developer in the developer accommodating portion, is transferred between the airflow dispersion member 23 and the developer supply roller 31. Good. In addition, a charge releasing member 25 that discharges negative charges is disposed inside the developer supply roller 31. In addition, a mesh electrode 29 is provided between the developer supply roller 31 and the developing roller 22 as a counter electrode to which the charge discharged from the charge discharging member 25 reaches. In the developing device 10 according to the first exemplary embodiment, the charge release member 25 and the mesh electrode 29 constitute a charge applying unit that applies a charge to the toner T.

Hereinafter, each part of the developing device 10 of Example 1 will be described in more detail.
In the initial use state of the developing device 10, 100 to 150 [g] of toner T exists in the hopper 14. In this, an agitator 28 with blades around the rotation axis is disposed and is rotating. As a result, the developer can be transferred little by little between the airflow discharge portion 24 and the developer supply roller 31.

The airflow discharge unit 24 includes a box-shaped casing 24b whose upper end is open, an airflow dispersion member 24a that covers the opening of the casing 24b, an air pipe 26, and an air pump 60. The surface of the airflow dispersion member 24a has an inclination of about 5 to 10 [°] with respect to the horizontal plane. The airflow dispersion member 24a is a sheet member obtained by solidifying a PTFA resin, and is a porous body having a plurality of openings communicating in the vertical direction. The size of the plurality of openings of the airflow dispersion member 23 is smaller than the particle size of the toner T, and prevents the toner T from entering the casing 24b.
An air pump 60 is connected to the casing 24b via an air pipe 26, and an air flow F1 is supplied to the inside of the airflow discharge portion. The casing 24b is in a state where the airflow distribution member 23 is sealed except for the opening where the airflow dispersion member 23 is provided and the connection portion with the air pipe 26, and the air flow F1 supplied via the air pipe 26 is located above the opening of the airflow dispersion member 23. To be released.

The developer supply roller 31 is a porous body having a hollow portion and having a plurality of suction holes 31a in which the hollow portion and the outer peripheral surface communicate with each other. A shaft member (not shown) is connected to one end of the hollow portion of the developer supply roller 31 so as to close the hollow portion. A drive motor (not shown) is connected to a shaft member (not shown), and rotates the developer supply roller 31 in the clockwise direction in the drawing. An air pipe 32 connected to a suction pump 61 is provided at the other end of the hollow portion of the developer supply roller 31 so as to block the hollow portion. Since one end of the hollow portion of the developer supply roller 31 is blocked by the shaft member, when the suction pump 61 is driven, air is sucked from the suction hole 31a of the developer supply roller 31 (in the first embodiment, 5 [L / min] is set).
In the hollow portion of the developer supply roller 31, a charge release member 25 is disposed. The charge release member 25 of the first embodiment is a wire charger including a wire and a casing surrounding the wire, and is a colontron. In the first embodiment, the wire is disposed in the hollow portion of the developer supply roller 31 so as to face the mesh electrode 29. The distance between the wire and the outer peripheral surface of the developer supply roller 31 is 5.5 [mm], the casing surrounding the wire is grounded, its width W is 15 [mm], and height H is 8 [mm]. It is. The dimensions including these casings are not one, but are determined based on the characteristics of the discharge, and the degree of freedom is sufficiently wide. Examples of the charge discharging member 25 include a mountain-shaped plate electrode, a needle electrode including a plurality of needles, and the like, and by disposing each in the hollow portion of the developer supply roller 31, The function as the charge discharging member 25 can be exhibited.

  The size of the suction hole 23 a of the developer supply roller 31 is smaller than the particle size of the toner T. By making the size of the suction hole 31a of the developer supply roller 31 smaller than the particle size of the toner T, the toner T is prevented from entering the charge releasing member 25 side. As a result, the toner T can be prevented from adhering to the charge discharging member 25, and the charge discharging member 25 can be maintained in a fresh state. The porous body constituting the developer supply roller 31 has a fibrous structure, and preferably has a configuration that allows discharge charges and air to pass therethrough and does not allow the toner T to pass through. For example, Temish manufactured by Nitto Denko Corporation Etc. are preferred.

  Between the developer supply roller 31 and the developing roller 22, a mesh electrode 29 is disposed as a counter electrode of the charge discharging member 25. In Example 1, since the distance between the mesh electrode 29 and the developing roller 22 is 6 [mm] and the applied voltage is 100 [V], the electric field between the mesh electrode 29 and the developing roller 22 is 16.7 × 103. [V / m]. The area of the opening of the mesh electrode 29 is usually preferably 30 to 50%. The lower the area ratio of the electrode 29, the higher the efficiency with which charge can be imparted to the toner T. However, if the opening area ratio is too low, it becomes difficult for the charged toner T to pass through the electrode 29, so it is necessary to determine the value with an appropriate balance. The electrode disposed between the developer supply roller 31 and the developing roller 22 is not limited to a mesh shape, and may be a plurality of wires (for example, tungsten having a diameter of 40 to 90 [μm]). It becomes possible to select from the relationship. Further, the developing roller 22 can be used as a counter electrode. In this case, there is an advantage that the number of parts can be reduced. On the other hand, by providing a mesh electrode 29 as a counter electrode between the developer supply roller 31 and the developing roller 22, the potential difference between the charge discharging member 25 and the mesh electrode 29, and the mesh electrode 29 and the developing roller 22 By adjusting each potential difference, it is possible to independently control the charge application to the toner T and the supply of the toner T to the developing roller 22. For this reason, a more uniform image can be maintained over time. In the developing device 10 according to the first exemplary embodiment, the charge discharging member 25 and the mesh electrode 29 are provided in a facing region where the developing roller 22 and the developer supply roller 31 are opposed to each other. It may be arranged on the upstream side in the movement direction and on the downstream side of the region where the toner T is supplied from the airflow dispersion member 24a to the developer supply roller 31. In this case, it is necessary to provide an electrode for forming an electric field between the developing roller 22 and the developer supply roller 31 separately from the charge discharging member 25. It can be charged in advance. Further, since the counter electrode that faces the charge releasing member 25 does not need to allow the toner T to pass therethrough, a plate-like member or the like can be used, and the efficiency with which a charge can be imparted to the toner T can be improved. Further, the charge discharge member 25 is provided inside the casing 24 b of the airflow discharge unit 24, and the counter electrode is provided inside the developer supply roller 31, so that the toner T is charged between the developer supply roller 31 and the airflow discharge unit 24. May be given.

  The distance between the developer supply roller 31 and the development roller 22 is a maximum of several millimeters, and the set value can be appropriately selected by determining the electric field strength formed by the developer supply roller 31 and the development roller 22.

Next, the operation of the developer supply device 30 will be described.
Due to the rotation of the agitator 28, the toner T in the hopper 14 is supplied to the surface of the airflow dispersion member 24a little by little. By the agitator 28, the toner T supplied to the surface of the airflow dispersion member 24a disturbs the toner T in the direction perpendicular to the surface of the airflow dispersion member 24a by the release of the air F1 from the airflow discharge portion 24, and fluidizes the toner T. Further, since the airflow dispersion member 24a has an inclination of about 5 to 10 [deg.] With respect to the horizontal plane, the toner T in a state fluidized by the action of gravity on the surface is applied to the surface of the airflow dispersion member 24a. And move to a region facing the developer supply roller 31. The toner T that has moved to the area facing the developer supply roller 31 is attracted to the surface of the developer supply roller 31 by a suction force.

  When the toner T is in the accumulated state, an adhesion force due to contact of the individual toners T is generated, and a lump is formed. Therefore, the toner T remaining in the hopper 14 may form a lump, and the lump toner T may move to the surface of the airflow dispersion member 24a. In the first embodiment, since the airflow discharge portion 24 is provided, such a block of toner can be individually separated by the air discharged from the airflow discharge portion 24. The individually separated toner T is attracted to the developer supply roller 31. Therefore, the bulk toner T is not attracted to the surface of the development supply roller 31. Further, the toner T adsorbed on the surface of the developer supply roller 31 closes the suction hole 31 a on the surface of the developer supply roller 31, so that many layers of toner T are not adsorbed on the developer supply roller 31. As a result, the toner T can be held on the surface of the developer supply roller 31 in a substantially single layer state (preferably in a finely packed state).

  In addition, since the toner T is moved to the area facing the developer supply roller 31 by air, it is compared with the apparatus that mechanically moves the toner T to the area facing the developer supply roller 31 such as a transport screw. Thus, the stress applied to the toner T can be reduced. Further, since the toner T is attracted to the developer supply roller 31 by sucking air, the toner T that is not in contact with the developer supply roller 31 can adhere to the surface of the developer supply roller 31. As a result, it is possible to suppress contact between the toner T that is not adsorbed on the surface of the developer supply roller 31 and the developer supply roller 31, and it is possible to prevent stress from being applied to the toner T on the surface of the airflow dispersion member 24 a. can do.

The toner T adsorbed on the developer supply roller 31 is conveyed to a region facing the developing roller 22. In the region facing the developing roller 22, due to the electric field formed between the charge discharging member 25 and the mesh electrode 29, the charge discharged from the charge discharging member 25 moves in the direction of the developing roller 22 on which electrostatic attraction acts. To do. Then, the charge is applied to the toner T closing the suction hole 31 a through the suction hole 31 a of the developer supply roller 31. The toner T on the surface of the developer supply roller 31 that is sufficiently charged by being charged in the opposite area is statically generated by an electric field formed by the developing bias applied to the developing roller 22 and the voltage applied to the charge releasing member 25. Due to the attraction force, it moves electrostatically to the developing roller 22 against the attractive force and adheres to the surface of the developing roller 22. On the other hand, the toner T that is not sufficiently charged has a higher attractive force than the electrostatic attractive force due to the electric field between the developing roller 22 and the developer supply roller 31 and does not move to the developing roller 22. It continues to be adsorbed on the surface of the agent supply roller 31. As a result, it is possible to suppress low-charged or uncharged toner from adhering to the surface of the developing roller 31, and it is possible to suppress deterioration in image quality such as background stains. Further, the toner can be attached to the developing roller 22 without contacting the developer supplying roller 31 with the developing roller 22 through the toner T. Thereby, stress applied to the toner T when the toner T is supplied from the developer supply roller 31 to the developing roller 22 can be reduced. Further, since the toner in the substantially single layer state (preferably in a finely packed state) adheres to the surface of the developer supply roller 31, the development roller 22 surface can be developed without any number of layers of developer. A substantially one-layer developer can also be adhered to the surface of the roller 22.
On the other hand, the toner T that has not moved to the developing roller 22 is applied with a bias voltage, collected by the developer collecting member 27 that rotates in the same speed and in the same direction as the developing supply roller 31, and collected by the developer collecting member 27. The toner T is scraped off by the cleaning blade and returned to the hopper as appropriate.

  In the conventional developing device shown in FIG. 6, as shown in FIG. 8, the regulating blade 413 is brought into contact with the developing roller 22 via the toner T and pressed in order to prepare a developer thin layer before development. Thus, the film is leveled to a certain thickness, and the developing roller 22 faces the latent image carrier and development is performed. When such a thin layer is formed (FIG. 8), a strong stress is applied to the toner T, so that the toner T is easily deteriorated in a process using the toner T formed of resin. On the other hand, in the first embodiment, as described above, the developer in a substantially one-layer state can be adhered to the surface of the developing roller 22, so that the regulation of pressing with the toner T on the developing roller 22 as shown in FIG. Leveling by the blade 413 becomes unnecessary. As a result, the stress on the developer can be reduced as compared with the conventional developing device.

  In the first embodiment, since the charge is applied to the toner T adsorbed on the surface of the developer supply roller 31, the toner T is more efficiently compared with the prior application (Japanese Patent Application No. 2008-205124). Can be charged. This is because, as in the prior application, air is discharged from the airflow discharge member and charge is applied to the toner floating from the airflow discharge member, so the distance between the toner and the charge discharge portion is increased. It is difficult for electric charge to adhere to On the other hand, in the first embodiment, since charge is applied to the toner T adsorbed on the surface of the developer supply roller, the distance between the charge releasing member and the toner can be made shorter than that of the previous application. , The electric charge tends to adhere to the toner. As a result, the uncharged / weakly charged toner can be quickly charged to a predetermined charge amount, and the toner T can be charged more efficiently than in the prior application (Japanese Patent Application No. 2008-205124).

  The toner T adhering to the developing roller 22 adheres to the photoconductor 21 by the latent image electric field of the photoconductor 21 and the electric field generated by the developing bias applied to the developing roller 22 in the developing region, and is developed and visualized. On the other hand, the undeveloped toner T may be directly adhered to the developing roller 22 and transported again to the developing region for use in development, or may be collected from the developing roller by a collecting means and appropriately transferred to a hopper. You may make it return.

A power source Vd that applies a voltage to the developing roller 22, a power source Vch that applies a voltage to the charge discharge member 25, and a power source Ve that applies a voltage to the mesh electrode 29 are DC power sources.
Under the conditions of the first embodiment, the developer thin layer characteristic on the surface of the developing roller 22 that has passed through the region facing the developer supplying roller 31 due to surface movement is an adhesion amount of 0.33 [mg / cm ² ]. The average charge amount was −10.2 [μC / g].
Here, the toner T on the surface of the developing roller 22 that has passed through the region facing the developer supply roller 31 was collected, and the charge amount distribution was compared with the toner T before being used in the developing device 10. FIG. 3 shows a comparison of charge amount distributions. In FIG. 3, “before charging” is a graph showing the charge amount distribution of the toner T before being used in the developing device 10, and “after charging” passes through a region facing the developer supply roller 31 in the developing device 10. 4 is a graph showing a charge amount distribution of toner T on the surface of the developed roller 22. The charge amount distribution shown in FIG. 3 is data obtained by sampling 1000 to 3000 toners T using E-Spart Analyzer manufactured by Hosokawa Micron Corporation.
As shown in FIG. 3, it can be confirmed that the peak value of the charge amount distribution is shifted in the direction in which the negative charge is strengthened by the voltage applied to the charge releasing member, and further, the negative charge is strengthened as a whole. As a result, it was confirmed that an almost uncharged toner was given a charge by discharging, and when the toner T was supplied to the developing roller 22, an effect of increasing the negative charge amount distribution was obtained.

Next, the developing roller 22 that can be used in the developing device 10 of the present embodiment will be described.
Examples of the surface layer coating material of the developing roller 22 include a material containing a resin such as silicon, acrylic, polyurethane, or rubber. Another example of the material is a material containing fluorine. A so-called Teflon (registered trademark) material containing fluorine has low surface energy and excellent releasability, so that developer filming over time hardly occurs. Also, as general resin materials that can be used for the surface layer coating material, polytetrafluoroethylene (PTFE), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), tetrafluoroethylene / hexafluoropropylene polymer (FEP) , Polychlorotrifluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE), chlorotrifluoroethylene / ethylene copolymer (ECTFE), polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), etc. Can be mentioned. In order to obtain conductivity, a conductive material such as carbon black is often contained in this. Further, another resin may be mixed so that the toner TT adheres uniformly to the developing roller 22. Regarding the electrical resistance, the bulk resistivity including the coat layer is set, and the resistance and adjustment of the base layer are performed so that it can be set to 10 ³ to 10 ⁸ [Ω · cm]. Since the volume resistivity of the base layer of the developing roller 22 used in this embodiment is 10 ³ to 10 ⁵ [Ω · cm], the volume resistivity of the surface layer may be set slightly higher.

  Since the printer 100 according to this embodiment uses the rigid drum-shaped photosensitive member 21 based on an aluminum tube, the developing roller 22 of the developing device 10 has a hardness of 10 to 70 [°] when a rubber material is selected. The range of JIS-A) is good. The diameter of the developing roller 22 is preferably 10 to 30 [mm]. In the developing device 10 of the present embodiment, one having a diameter of 16 [mm] is used. Further, the surface of the developing roller 22 was appropriately changed to have a roughness Rz (10-point average roughness) of 1 to 4 [μm]. The range of the surface roughness Rz is 13 to 80 [%] with respect to the volume average particle diameter of the developer, and is a range in which the developer is conveyed without being buried in the surface of the developing roller 22. Here, silicon, butadiene, NBR, hydrin, EPDM, or the like can be used as a rubber material for the developing roller 22. Further, in order to reduce the hardness of the developing roller 22, an endless belt using a thin metal plate can be used.

  The developer used in the developing device 10 of the present embodiment needs to have an average particle diameter of 3 to 8 [μm] in order to realize a high quality image. The developer has a weight average particle size of 3 to 8 [μm], more preferably 4 to 7 [μm]. If the weight average particle size is less than 2 [μm], problems such as contamination in the machine due to scattering of the developer after long-term use, image density reduction in a low-humidity environment, and poor photoreceptor cleaning are likely to occur. When the weight average particle size exceeds 8 [μm], the resolution of fine spots of 100 [μm] or less is not sufficient, and the image quality tends to be inferior due to many scattering to non-image areas.

Here, details of the developer are shown below.
As resins, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene acrylic resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, polyethylene resin, silicon resin, butyral resin, terpene There are resins, polyol resins and the like. Examples of vinyl resins include styrene such as polystyrene, poly-p-chlorostyrene, and polyvinyltoluene, and homopolymers thereof: styrene-p-chlorostyrene copolymer, styrene-propylene copolymer, styrene-vinyltoluene copolymer. Polymer, styrene-vinyl naphthalene copolymer, styrene-methyl acrylate copolymer, styrene-ethyl acrylate copolymer, styrene-butyl acrylate copolymer, styrene-octyl acrylate copolymer, styrene-methacrylic copolymer Acid methyl copolymer, styrene-ethyl methacrylate copolymer, styrene-butyl methacrylate copolymer, styrene-α-chloromethyl methacrylate copolymer, styrene-acrylonitrile copolymer, styrene-vinyl methyl ether copolymer Coalescence, styrene-vinyl ethyl acetate Copolymer, styrene-vinyl methyl ketone copolymer, styrene-butadiene copolymer, styrene-isoprene copolymer, styrene-acrylonitrile-indene copolymer, styrene-maleic acid copolymer, styrene-maleic acid ester Styrene copolymers such as copolymers: polymethyl methacrylate, polybutyl methacrylate, polyvinyl chloride, polyvinyl acetate and the like.

The polyester resin is composed of a dihydric alcohol as shown in the following group A and a dibasic acid salt as shown in the group B, and further a trihydric or higher alcohol as shown in the group C or Carboxylic acid may be added as a third component.
Group A: ethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4 butanediol, neopentyl glycol, 1,4 butenediol, 1,4-bis (hydroxymethyl) cyclohexane Bisphenol A, hydrogenated bisphenol A, polyoxyethylenated bisphenol A, polyoxypropylene (2,2) -2,2′-bis (4-hydroxyphenyl) propane, polyoxypropylene (3,3) -2, 2-bis (4-hydroxyphenyl) propane, polyoxyethylene (2,0) -2,2-bis (4-hydroxyphenyl) propane, polyoxypropylene (2,0) -2,2′-bis (4 -Hydroxyphenyl) propane and the like.
Group B: maleic acid, fumaric acid, mesaconic acid, citraconic acid, itaconic acid, glutaconic acid, phthalic acid, isophthalic acid, terephthalic acid, cyclohexanedicarboxylic acid, succinic acid, adipic acid, sebacic acid, malonic acid, linolenic acid, or These acid anhydrides or esters of lower alcohols.
Group C: Trivalent or higher alcohols such as glycerin, trimethylolpropane and pentaerythritol, and trivalent or higher carboxylic acids such as trimellitic acid and pyromellitic acid. As the polyol resin, an alkylene oxide adduct of an epoxy resin and a dihydric phenol, or a compound having one active hydrogen in the molecule that reacts with the glycidyl ether and the epoxy group, and an active hydrogen that reacts with the epoxy resin in the molecule. There are those obtained by reacting two or more compounds.

The following are used as pigments used in the developer of the present embodiment.
Examples of black pigments include azine dyes such as carbon black, oil furnace black, channel black, lamp black, acetylene black, and aniline black, metal salt azo dyes, metal oxides, and composite metal oxides.
Examples of yellow pigments include cadmium yellow, mineral fast yellow, nickel yellow, navel yellow, naphthol yellow S, hansa yellow G, hansa yellow 10G, benzidine yellow GR, quinoline yellow lake, permanent yellow NCG, and tartrazine lake. .
Examples of the orange pigment include molybdenum orange, permanent orange GTR, pyrazolone orange, Vulcan orange, indanthrene brilliant orange RK, benzidine orange G, and indanthrene brilliant orange GK.
Examples of red pigments include Bengala, Cadmium Red, Permanent Red 4R, Resol Red, Pyrazolone Red, Watching Red Calcium Salt, Lake Red D, Brilliant Carmine 6B, Eosin Lake, Rhodamine Lake B, Alizarin Lake, Brilliant Carmine 3B.
Examples of purple pigments include fast violet B and methyl violet lake.
Examples of blue pigments include cobalt blue, alkali blue, Victoria blue lake, phthalocyanine blue, metal-free phthalocyanine blue, phthalocyanine blue partially chlorinated, first sky blue, and indanthrene blue BC.
Examples of green pigments include chrome green, chromium oxide, pigment green B, and malachite green lake.

  These can use 1 type (s) or 2 or more types. Especially in color developers, it is essential to uniformly disperse a good pigment. Instead of putting the pigment directly into a large amount of resin, a master batch in which the pigment is once dispersed at a high concentration is prepared and diluted. The method of throwing in the form is used. In this case, a solvent is generally used to help dispersibility. However, there is a problem of environment and the like, and the developer used in this embodiment is dispersed using water. When water is used, temperature control is important so that residual moisture in the masterbatch does not become a problem.

  A release agent can be internally added to the developer used in the exemplary embodiment in order to prevent an offset at the time of fixing. Release agents include natural waxes such as candelilla wax, carnauba wax, rice wax, montan wax and derivatives thereof, paraffin wax and derivatives thereof, polyolefin wax and derivatives thereof, sazol wax, low molecular weight polyethylene, and low molecular weight polypropylene. And alkyl phosphate esters. The melting point of these release agents is preferably 65 to 90 [° C.]. When the temperature is lower than this range, blocking during storage of the developer is likely to occur, and when the temperature is higher than this range, an offset is likely to occur in a region where the fixing roller temperature is low.

An additive may be added to the developer for the purpose of improving the dispersibility of a release agent or the like. As additives, styrene acrylic resin, polyethylene resin, polystyrene resin, epoxy resin, polyester resin, polyamide resin, styrene methacrylate resin, polyurethane resin, vinyl resin, polyolefin resin, styrene butadiene resin, phenol resin, butyral resin, terpene resin, There is a polyol resin or the like, and a mixture of two or more of these resins may be used.
Crystalline polyester may be used as the developer resin. It is an aliphatic polyester having crystallinity, having a sharp molecular weight distribution, and increasing the absolute amount of its low molecular weight as much as possible. This resin undergoes a crystal transition at the glass transition temperature (Tg), and at the same time, the melt viscosity suddenly decreases from the solid state and exhibits a fixing function to paper. By using this crystalline polyester resin, the Tg and molecular weight of the resin can be lowered too much, and the developer can be fixed at low temperature. Therefore, there is no decrease in storage stability associated with a decrease in Tg. Further, there is no excessively high gloss and offset resistance deterioration due to the low molecular weight. Therefore, the introduction of the crystalline polyester resin is very effective for improving the low-temperature fixability of the developer.
The circularity of the developer particles was measured as an average circularity using a flow particle image analyzer FPIA-1000 (manufactured by Toa Medical Electronics Co., Ltd.).

Further, the developer used in the present embodiment adheres or fixes an inorganic fine powder to the developer surface as a fluidity improver. The average particle size of the inorganic fine powder is suitably 10 to 200 [nm]. When the particle size is smaller than 10 [nm], it is difficult to produce an uneven surface having an effect on fluidity. When the particle size is larger than 200 [nm], the powder shape becomes rough, and the developer shape Problems arise.
As the inorganic fine powder, oxidation of Si, Ti, Al, Mg, Ca, Sr, Ba, In, Ga, Ni, Mn, W, Fe, Co, Zn, Cr, Mo, Cu, Ag, V, Zr, etc. And composite oxides. Of these, fine particles of silicon dioxide (silica), titanium dioxide (titania), and alumina are preferably used. Furthermore, it is effective to perform a surface modification treatment with a hydrophobizing agent or the like. Typical examples of the hydrophobizing agent include the following.
Dimethyldichlorosilane, trimethylchlorosilane, methyltrichlorosilane, allyldimethyldichlorosilane, allylphenyldichlorosilane, benzyldimethylchlorosilane, bromomethyldimethylchlorosilane, α-chloroethyltrichlorosilane, p-chloroethyltrichlorosilane, Chloromethyldimethylchlorosilane, chloromethyltrichlorosilane, hexaphenyldisilazane, hexatolyldisilazane, etc.

The inorganic fine powder is preferably used in an amount of 0.1 to 3% by weight based on the developer. If it is less than 0.1 [% by weight], the effect of improving the developer aggregation is poor. If it exceeds 3 [% by weight], the developer scatters between fine wires, contamination in the machine, scratches or abrasion of the photoreceptor, etc. Problems tend to occur.
In addition, a charge control agent may be attached or fixed to the surface of at least a powder composed of a resin and a pigment so that the powder surface shape has a small period and a large period. The average particle size is optimally as small as 10 to 200 [nm]. When the particle size is smaller than 10 [nm], it is difficult to produce an uneven surface having an effect on fluidity. When the particle size is larger than 200 [nm], the powder shape becomes rough, and the developer shape Problems arise.

  In addition, the developer used in the exemplary embodiment is further added with other additives, for example, a lubricant powder such as Teflon (registered trademark) powder, zinc stearate powder, and polyvinylidene fluoride powder within a range that does not substantially adversely affect the developer; Alternatively, a polishing agent such as cerium oxide powder, silicon carbide powder, and strontium titanate powder; or a conductivity imparting agent such as carbon black powder, zinc oxide powder, and tin oxide powder can be used in small amounts as a developability improver.

FIG. 4 is a graph comparing the developer burying rank of the developer over time between a developing device to which the present invention is applied and a conventional developing device. As shown in FIG. 4, in the present invention, the additive burying rank is maintained at 4.7 even if 100 [k sheets] is exceeded, whereas in the current one, the rank is 3 at 20 [k sheets]. , 50 [k] was ranked 1st.
In addition, the evaluation criteria of each rank of the additive buried rank shown in FIG. 4 are as follows.
Rank 1: All external additives are buried and not left on the surface.
Rank 2: Most external additives are buried in the toner and do not remain on the surface.
Rank 3: Most external additives are buried in the toner, but remain on the toner surface.
Rank 4: A state in which some external additives are buried.
Rank 5: The external additive is not buried.

  Thus, like the developer supply device 30 provided in the developing device 10 of the present embodiment, the developer is supplied to the developer carrier and the charge is applied to the developer without using the conventional triboelectric charging. By using non-electrostatic adhesion force and ion shower by discharge, image formation can be performed without applying mechanical stress to the developer, so that deterioration of the developer can be prevented over time. Quality can be maintained.

[Example 2]
Next, a second embodiment (hereinafter referred to as a second embodiment) of the developing device 10 having the developer supply device having the characterizing portion of the present invention will be described. Note that the description of the configuration common to the first embodiment is omitted.
FIG. 5 is a schematic configuration diagram of the developing device 10 according to the second embodiment. 5A is a cross-sectional view in the vicinity of the developing roller 22 of the developing device 10 on a surface orthogonal to the rotation axis of the developing roller 22, and FIG. 5B is a cross-sectional view indicated by a broken line α in FIG. 2 is a schematic diagram of a developer supply device 30 provided in the developing device 10. FIG.

In the developing device 10 of the second embodiment, the toner T is conveyed from the toner hopper 43 to the upper surface of the airflow dispersion member 24a above the airflow discharge section 24 by the powder pump 40, which is a developer pump, as shown in FIG. Supplied.
The powder pump 40 mainly includes a stator 42 and a rotor 41. This powder pump 40 is a so-called commonly known “Mono pump”, and a male screw type rotor 41 inserted into a female screw type stator 42 is connected to a drive shaft (not shown) via a connecting rod. Rotate around the eccentric center. As a result, the toner T, which is a transfer object, is sucked into the stator 42 by the pumping action of the rotor 41 having a circular cross section that rotates and moves in the longitudinal axial direction in the oblong hole (rotation eccentric space) of the cross section of the stator 42. Then, the toner T is discharged through the stator 42, and compressed air is supplied by an air supply device (not shown) before and after that to flow the toner T in a diffused state, thereby realizing the conveyance of the toner T. Thus, since the toner T can be flowed in a diffused state and the toner T can be transported, the stress applied to the toner during toner transport can be reduced. The toner in the toner hopper 43 is conveyed to the airflow discharge unit 24 by the powder pump 40 and then supplied to the surface of the developing roller by the same mechanism as in the first embodiment.

  As the powder pump 40, a material having a surface energy lower than that of the toner T (a material that is easily charged with a polarity opposite to that of the toner) on the inner surface of the stator 42 or the surface of the rotor 41, that is, on the inner wall of the powder pump 40. For example, by applying a resin material such as silicon or urethane with a thickness of about 1 to 10 [μm], or by forming a three-dimensional fiber structure inside the pump and applying the material that is easily charged to the structure portion. Further, the mechanical stress applied to the toner T before reaching the charging / supply area between the airflow releasing member 24 and the developing roller 22 can be greatly reduced.

As described above, as the first embodiment and the second embodiment, the best mode for carrying out the present invention has been described with reference to the drawings. Note that it is easy for a person skilled in the art to make other embodiments by changing or correcting the present invention within the scope of the claims, and these changes and modifications are included in the scope of the claims. The following description is an example of the best mode of the present invention, and does not limit the scope of the claims.
The developing method according to the present invention uses a one-component developing method used in a contact or non-contact developing method. As the contact or non-contact development method, various known methods are used. For example, contact development using an aluminum sleeve, contact development using a conductive rubber belt, non-contact development using a development sleeve in which a conductive resin layer containing carbon black, metal filler, etc. is formed on the surface of an aluminum tube. Etc.

As described above, the developer supply device 30 according to the present embodiment carries the toner T as a one-component developer on the surface that moves, and supplies the toner T to the latent image on the photosensitive member 21 that is a latent image carrier, thereby Toner is supplied to a developing roller 22 which is a developer carrying member for developing an image. The developer supply device 30 is disposed so as to be spaced from the developing roller 22 and has a developer supplying roller 31 serving as a developer conveying member that conveys the toner T to a region facing the developing roller 22. A suction pump 61 is provided as suction means for sucking air from the suction holes 31 a formed in the agent supply roller 31 and adsorbing the toner T on the surface of the developer supply roller 31. In addition, a charge applying unit including a charge releasing member 25 for applying a charge to the toner T in a non-contact manner with the toner T, a mesh electrode 29 serving as a counter electrode, or the like is provided during or before passing through the region facing the developing roller 22. .
With such a configuration, it is possible to reduce the stress applied to the toner T when the toner T is adhered to the surface of the developer supply roller. Further, the stress applied to the toner T when the toner T is charged can be reduced. Further, the stress applied to the toner T when the toner T is adhered from the developing supply roller 31 to the developing roller 22 can be reduced. Further, it is possible to suppress weakly charged toner and uncharged toner from adhering to the developing roller 22.

  Further, a potential difference is formed between the developer supply roller 31 and the developing roller 22 in the facing region between the developing roller 22 and the developer supplying roller 31, and the one-component developer on the surface of the developer supplying roller 31 is transferred in the facing region. Electrostatically adheres to the surface of the developing roller 22. Thus, the toner T can be attached to the developing roller 22 without contacting the developer supplying roller 31 with the developing roller 22 through the toner T. As a result, the stress applied to the toner T when the toner T is supplied from the developer supply roller 31 to the developing roller 22 can be reduced.

Further, by disposing the charge release member 25 in the hollow portion of the developer supply roller 31 so as to face the development roller 22, the developer supply roller 31 and the development roller are developed by the potential difference between the charge release member 25 and the development roller 22. A potential difference can be formed with the roller 22. As a result, the electric charge can be discharged from the charge discharge member 25 toward the development roller 22 due to the potential difference between the charge discharge member 25 and the development roller 22. That is, the developing roller 22 can be used as the counter electrode 29. Then, the charge released from the charge release member 25 can give the charge to the toner T adsorbed on the developer supply roller 31 through the suction hole 31a in which the hollow portion and the surface communicate with each other. In addition, the toner T charged with an electric charge can be electrostatically moved to the developing roller 31 due to a potential difference between the charge releasing member 25 and the developing roller 31, and can be attached to the developing roller 31. As described above, the charge discharging member 25 is disposed in the hollow portion of the developer supply roller 31 so as to face the developing roller 31, thereby simultaneously achieving two functions of charge discharging and toner supply to the developing roller 22. Can be made.
Further, since charge can be applied to the toner T adsorbed on the surface of the developer supply roller 31, the toner T can be charged more efficiently than in the case where charge is applied to the flowing toner. Can be made.

  Further, by disposing the mesh electrode 29 as a counter electrode between the developing roller 22 and the developer supply roller 31, the potential difference between the charge discharging member 25 and the mesh electrode 29, the mesh electrode 29 and the developing roller 22, By adjusting the potential difference between the two, the charge application to the toner T and the supply of the toner T to the developing roller 22 can be independently controlled. For this reason, a more uniform image can be maintained over time.

  The charge discharging member 25 is a dischargeable wire charger. As a result, a region closest to the mesh electrode 29 can be set widely, the discharge amount is easily stabilized, and the toner T can be uniformly charged.

  Further, since the diameter of the suction hole 31a is made smaller than the diameter of the toner T, the toner T does not enter the charge releasing member 25 side, so that the charge releasing member 25 can be kept fresh.

  Also, an airflow discharge unit 24 that is disposed below the developer supply roller 31 so as to have a space between the developer supply roller 31 and discharges an airflow upward, and the developer supply roller 31. And a developer transferring means for transferring the toner between the air discharge unit 24 and the air flow releasing unit 24. According to such a configuration, the toner transferred between the developer supply roller 31 and the airflow release unit 24 is fluidized by the airflow released from the airflow release unit 24. As a result, the bulky toner can be separated individually, and the separated toner can be adsorbed to the developer supply roller 31. Therefore, it is possible to adhere the toner in a substantially single layer state (preferably, a finely packed state) onto the developer supply roller 31.

  Further, by using the powder pump 40 as a developer pump as the developer transfer means, the toner T can be flowed in a diffused state and the toner T can be transported, so that stress applied to the toner during toner transport is increased. Can be reduced.

  Further, the developing device 10 of the present embodiment includes a developing roller 22 as a developer carrying member that carries toner T, which is a one-component developer, and a developer supply unit that supplies the developer to the developing roller 22. Then, the toner T on the developing roller 22 is supplied to the latent image on the photosensitive member 21 which is a latent image carrier to develop the latent image. Since the developer supply device 30 described with reference to the first embodiment or the second embodiment is provided as the developer supply means, high-quality development can be performed stably over time. Further, there is no frictional charging between the member constituting the developing device 10 and the toner T, and it is possible to prevent the dissolved toner from adhering to the member, thereby extending the life of the developing device.

  Further, in the printer 100 as the image forming apparatus of the present embodiment, the developing unit causes the toner T, which is a one-component developer, to develop the latent image on the latent image on the photoreceptor 21 that is the latent image carrier. The toner image thus obtained is finally transferred to a recording material to form an image. Since the developing device 10 described with reference to the first or second embodiment is provided as a developing unit, high-quality image formation can be performed stably over time. Further, there is no frictional charging between the member constituting the developing device 10 and the toner T, and it is possible to prevent the dissolved toner from adhering to the member, thereby extending the life of the developing device. The overall life can be extended.

DESCRIPTION OF SYMBOLS 1 Intermediate transfer belt 3 Paper discharge roller 4 Fixing device 5 Secondary transfer roller 6 Registration roller 7 Paper feed roller 8 Paper feed cassette 9 Optical writing unit 10 Developing device 11 Primary transfer device 12 Intermediate transfer body cleaning device 17 Charging device 18 Photosensitive Body cleaning device 20 Toner image forming portion 21 Photoconductor 22 Developing roller 24a Airflow dispersion member 24 Airflow releasing portion 25 Charge releasing member 26 Air pipe 27 Recovery roller 28 Agitator 29 Mesh electrode 30 Developer supply device 31 Developer supply roller 31a Suction hole 40 Powder pump 41 Rotor 42 Stator 43 Toner hopper 61 Suction pump 100 Printer 412 Supply roller 413 Regulating blade

Japanese Patent No. 3817496

Claims (10)

Development in which a one-component developer is carried on a surface that moves, and the one-component developer is supplied to the latent image on the latent image carrier to develop the latent image. In the agent supply device,
Oppositely arranged so as to have a gap between the developer carrier and the one-component developer is held on the surface, and the surface moves endlessly so that the one-component developer is separated from the developer carrier. A developer conveying member that conveys to the facing area;
A suction means for sucking air from a suction hole formed in the developer transport member to adsorb the one-component developer on the surface of the developer transport member;
Charge that imparts a charge to the one-component developer in a non-contact manner with the one-component developer before the one-component developer on the surface of the developer conveying member passes through the exit of the area facing the developer carrier. And a developer supplying device. The developer supply device according to claim 1.
In the facing region, a potential difference is formed between the developer transport member and the developer carrying member, and in the facing region, a one-component developer on the surface of the developer transporting member is electrostatically applied to the developer carrying member surface. A developer supply device characterized in that the developer supply device is attached. The developer supply apparatus according to claim 2, wherein
The developer conveying member has a hollow portion, and is formed of a porous body having a plurality of suction holes communicating the surface and the hollow portion,
The charge imparting means includes at least a charge releasing member that discharges charges,
The developer supply apparatus, wherein the charge releasing member is disposed in a hollow portion of the developer transport member so as to face the developer carrying member. The developer supply device according to claim 3.
The charge applying means has a counter electrode facing the charge discharging member,
The developer supply apparatus, wherein the counter electrode is disposed between the developer carrier and the developer transport member. The developer supply device according to claim 3 or 4,
A developer supply apparatus using a dischargeable wire charger as the charge discharging member. The developer supply device according to any one of claims 3 to 5,
A developer supply apparatus, wherein the suction hole has a diameter smaller than that of the one-component developer. In the developer supply apparatus according to any one of claims 1 to 6,
An air flow releasing means disposed below the developer transport member so as to have a space between the developer transport member and discharging an air flow upward;
A developer supply apparatus, comprising: a developer transport unit configured to transport the one-component developer between the developer transport member and the airflow discharge unit. The developer supply apparatus according to claim 7.
A developer supply apparatus using a developer pump as the developer transfer means. A developer carrying member for carrying a one-component developer; and developer supplying means for supplying the developer to the developer carrying member. The developer on the developer carrying member is placed on the latent image carrier. In a developing device that supplies a latent image to develop the latent image,
A developing device comprising the developer supplying device according to claim 1 as the developer supplying means. An image in which the latent image on the latent image carrier is developed by attaching a one-component developer to the latent image to develop the latent image, and the resulting toner image is finally transferred to a recording material to form an image. In the forming device,
An image forming apparatus using the developing device according to claim 9 as the developing unit.

Images