JPH04219771A - Developing device - Google Patents

Abstract

PURPOSE:To recover toner remaining on a developing sleeve after processing and remove ghosts without providing a scraper for scarping a developer on the developing sleeve, which is necessary in conventional developing devices. CONSTITUTION:A developing device 17 comprises a toner recovering roller 176 provided in a position apart from a developing sleeve 171. A bias voltage of a bias supply 32 is applied to the toner recovering roller 176 whereby toner remaining on the developing sleeve 171 after processing is stuck to the toner recovering roller 176 which is not in contact with the developing sleeve 171, to be recovered.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device that accommodates a developer, deposits the developer on a developing sleeve, and enables visualization using the developer.

0002

[Prior Art] For example, in image formation using electrophotography, a latent image is formed and developed on an image carrier according to a document or image data, a toner image is formed on the image carrier, and then a toner image is formed on a transfer material. An image is obtained by transferring the toner image to.

A conventional developing device used for the above-mentioned development has a configuration as shown in FIG. 6, for example. That is, inside the developing device 17, a developing sleeve 171, supply rollers 172, 173, a magnet roller 174, a regulating member 175, a scraper 179, etc. are provided. The developing sleeve 171 encloses a fixed magnet roller 174, and is driven and rotated in a counterclockwise direction while maintaining a predetermined developing distance between the developing sleeve 171 and the circumferential surface of the image carrier 10. Note that the developing sleeve 171 and the image carrier 10 may be in contact with each other. The regulating member 175 is rigid and magnetic, and the developing sleeve 17
1 with a predetermined load without the presence of developer. A pair of stirring screws 172, 173 are
It has a screw structure, and functions to transport and circulate the developer in opposite directions, sufficiently stir and mix the toner and carrier, and then send the toner and carrier to the developing sleeve 171 as a developer.

[0004] The magnet roller 174 is composed of eight pole magnets of equal magnetic force, with N poles and S poles arranged at equal intervals, and a repulsion magnetic field is formed at the portion in contact with the scraper 179. In order to facilitate the peeling off of the developer, one pole is removed, resulting in seven poles, which are fixedly enclosed within the developing sleeve 171.

The stirring screw 172 and the stirring screw 173 are members that also serve as stirring members that rotate in opposite directions.
By the thrust of The developer is applied in a layered manner. The developer on the surface of the developing sleeve 171 is controlled by the regulating member 175, which is a cylindrical rod made of a magnetic material and is provided opposite to the magnetic pole of the magnet roller 174.
By pressing 71, it is shaped into a uniform thin layer.

[0006] This developer layer, which forms a thin layer by adhering to the peripheral surface of the developing sleeve 171, spreads the latent image on the peripheral surface of the image carrier 10, which is conveyed clockwise in the developing area, by the above-mentioned development interval. A toner image is formed through non-contact reversal development.

During this non-contact development, a developing bias containing an alternating current component in addition to a direct current component is applied to the developing sleeve 171 from a power source (not shown), and as a result, the developing sleeve 17
Only the toner in the developer is selectively transferred and adhered to the surface of the latent image.

The developer having consumed the toner component has a high carrier ratio, is transported by the developing sleeve 171, is peeled off and collected by the scraper 179, and is again mixed with a developer having a high toner ratio.

As mentioned above, when developing using an alternating electric field in a developing device using a two-component developer, the effect of selectively transferring only the toner to the surface of the latent image becomes high, so that the inside of the developing brush In other words, there is a difference (presence or absence) in toner density between the developing area and the non-developing area near the developing sleeve, and a so-called ghost occurs on the developing sleeve, and the difference in toner density on the developing sleeve affects memory during the next development. This resulted in poor development, deterioration in image quality, etc.

In the conventional developing device, in order to remove the above-mentioned ghost, the developer on the developing sleeve is scraped and removed by bringing the scraper into sliding contact with the developing sleeve as described above. Then, by applying new developer onto the developing sleeve and forming a thin layer,
This prevents poor development, deterioration in image quality, etc.

[0011]

[Problems to be Solved by the Invention] However, in the method described above in which the scraper is brought into sliding contact with the developing sleeve to strip off the developer on the developing sleeve, since the scraper is brought into sliding contact, the developing sleeve is The rotating torque increases, which increases the load on the driving means for the developing sleeve. Also, the scraper and the developing sleeve wear out, resulting in significantly poor durability. Furthermore, the stress on the toner and developer on or near the developing sleeve increases. A number of problems have arisen, such as an increase in the amount of water and accelerated deterioration of the developer.

It is an object of the present invention to eliminate the need to provide a scraper that is in sliding contact with the developing sleeve, which is one of the roots of the many problems mentioned above, or to eliminate toner remaining on the developing sleeve before the scraper. An object of the present invention is to provide a developing device capable of removing ghosts.

[0013]

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a developing sleeve that performs development using an alternating electric field in a developing section with a two-component developer attached to the surface of the developing sleeve, and and a rotating member rotatably provided at a position further downstream in the rotational direction of the developing sleeve and away from the developing sleeve, and applying an alternating current electric field between the developing sleeve and the rotating member. This is achieved by a developing device characterized by:

[0014]

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a main sectional view of an electrophotographic image forming apparatus that can be equipped with a developing device of the present invention.

In FIG. 1, a photosensitive belt 10 serving as an image carrier is a flexible belt having a photosensitive layer deposited or coated on its surface, and is installed between two rotating rollers 11 and 12. It is stretched by a tension roller 13. At least one rotating roller rotates via a drive gear (not shown) that meshes with a gear provided on the apparatus main body, and conveys the photoreceptor belt 10 in a clockwise direction. Furthermore, the distance maintaining member 14 maintains a constant distance between the photoreceptor belt 10 and the developing device 17 of the present invention, which will be described later, making it possible to stably form a good image.

Charging means 1 is provided around the photoreceptor belt 10.
5, an exposure means 16, a developing device 17, a transfer means 18, and a cleaning means 19 are provided.

The charging means is provided to uniformly charge the photosensitive layer on the surface of the photoreceptor belt 10 to a predetermined polarity, and is an existing charger 15 such as a corona charger or a scorotron charger. For the body, a scorotron charger is preferably used.

The exposure means is a semiconductor laser writing system unit 16, which exposes the surface of the photoreceptor belt 10 charged by the charger 15 to form an electrostatic latent image.

The developing device is a plurality of developing devices 17Y, 17M, 17C, and 17Bk each containing developers of different colors, such as yellow, magenta, cyan, and black toners and carriers. Each of these developing units 17Y, 17M, 17C, and 17Bk has a function of developing an electrostatic latent image on the photoreceptor belt 10 into a toner image using a non-contact development method, as will be described in detail later. . Unlike the contact development method, this non-contact development method does not damage the toner image previously formed on the photoreceptor belt 10 and does not hinder the movement of the photoreceptor belt 10, so it is possible to obtain a good color image. I can do it.

The transfer means uses a transfer device 18 such as a transfer corona discharger to transfer the toner image formed on the photoreceptor belt 10 onto a transfer material. As this transfer means, an existing transfer member such as a transfer drum may be used instead of the transfer device 18.

The cleaning means 19 has a cleaning blade 191 and a cleaning roller 192, and is kept at a position apart from the surface of the photoreceptor belt 10 during the image forming process, and is used for cleaning after the toner image is transferred to the transfer material. It is provided so as to clean the photoreceptor belt 10 by coming into pressure contact with the surface of the photoreceptor belt 10 only occasionally.

The image forming process by the image forming apparatus having the above-described configuration is performed as follows.

First, when an image signal of a first color outputted from an image reading device separate from the image forming device is input to the laser writing system unit 16, a semiconductor laser in the laser writing system unit 16 (see FIG. (not shown)
A laser beam is generated. A polygon mirror 16 whose laser beam is rotated by a drive motor 161
2, and is projected onto the circumferential surface of the photoreceptor belt 10, which has been uniformly charged to a predetermined charge by the charger 15, through an fθ lens 163 and two mirrors 164, thereby forming a bright line.

On the other hand, regarding the sub-scanning direction, a belt index (not shown) corresponding to a specific position of the photoreceptor belt 10 is detected, or a print command signal is received, and the process is performed based on this detection or command signal. A main scanning line on which modulation of the semiconductor laser by the image signal is started is determined. When scanning is started, in the main scanning direction, the laser beam is detected by an index sensor (not shown), and based on this detected signal, modulation of the semiconductor laser by the image signal of the first color is started. The modulated laser beam is scanned over the surface of the photoreceptor belt 10. Therefore, a latent image corresponding to the first color is formed on the uniformly charged surface of the photoreceptor belt 10 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photoreceptor belt 10.

This latent image is developed by a developing device 17Y containing yellow toner corresponding to the first color among the developing means, and a yellow toner image is formed on the surface of the photoreceptor belt 10. Thereafter, the photoreceptor belt 10 is rotated while holding the yellow toner image on its surface.
After passing under the cleaning means 19 which is spaced apart from the surface of the second color, image formation of the second color begins.

That is, the photoreceptor belt 10 on which the yellow toner image has been formed is uniformly charged again by the charger 15, and then the image signal of the second color is inputted to the laser writing system unit 16, and the above-mentioned first color image signal is input to the laser writing system unit 16. As in the case of the image signal of one color, writing is performed on the surface of the photoreceptor belt 10 to form a latent image. The latent image is developed by a developer 17M containing magenta toner as the second color. A magenta toner image is formed in the presence of a previously formed yellow toner image.

Similarly, after forming a latent image using the third color image signal, a cyan toner image is formed in the developing device 17C containing cyan toner, and furthermore, after forming a latent image using the fourth color image signal, a black toner image is formed. Developing device 17Bk that stores toner
The black toner image is superimposed on the surface of the photoreceptor belt 10 to form a color toner image on the surface of the photoreceptor belt 10.

Each of these developing devices 17Y, 17M, 17C,
A DC or even AC bias is applied to the 17Bk developing sleeve, and the photoreceptor belt 1 has its base grounded.
0, reversal development (jumping development) is performed in a non-contact manner.

The color toner image formed on the surface of the photoreceptor belt 10 as described above is supplied from a paper feed cassette 20 by a paper feed roller 21, and is transferred to a transfer material by a timing roller 22 in synchronization with the color toner image. transcribed. The transfer device 18 performs transfer by applying a high-voltage power output having a polarity opposite to that of the toner.

The transfer material onto which the color toner image has been transferred in this manner is reliably separated and conveyed upward by the photosensitive belt 10, which changes direction rapidly (with a small diameter curvature) along the rotating roller 11. After the toner is melted and fixed on the transfer material by the fixing roller 23, the transfer material is discharged by the paper discharge roller 24 onto the upper surface of the upper cover 25 which also serves as a paper discharge tray.

On the other hand, the photoreceptor belt 10, which has completed the transfer of the color toner image onto the transfer material, is further conveyed clockwise to the cleaning blade 191 and the cleaning roller 1.
Remaining toner is removed and cleaning is performed by the cleaning means 19 with 92 in pressure contact. Waiting for the end of cleaning, the cleaning blade 191 is separated from the photoreceptor belt 10 again, and a little later, after the cleaning roller 192 smoothes out the toner accumulated on the tip of the cleaning blade 191, the cleaning roller 192 is separated. , enters a new image formation process.

Next, before explaining the developing device of the present invention, the developer used in the developing device of the present invention will be explained. The developer used in the present invention is a two-component developer that can easily triboelectrically charge toner particles and can use color toner without color turbidity caused by magnetic substances. This two-component developer is composed of a ferrite core coated with a resin material and has a particle size of 10 to 100 μm (preferably 30 μm).
A developer composed of an insulating magnetic carrier having a particle diameter of 1 to 60 μm and a non-magnetic toner having a particle size of 1 to 10 μm is particularly preferably used. The insulating properties of the carrier not only allow a high alternating electric field to be applied to the developing device, but also have the effect that breakdown does not occur even when a high electric field is applied between the developing sleeve 171 and the collection roller 176. The structure of the toner will be explained below.

(1) Thermoplastic resin (binder) 80
~90wt% Examples: polystyrene, styrene acrylic polymer, polyester, polyvinyl butyral, epoxy resin, polyamide resin, polyethylene, ethylene vinyl acetate copolymer, etc., or mixtures of the above.

(2) Pigment (coloring agent) 0-15wt
% Examples: Black: Carbon black yellow: Benzidine derivative Magenta: Rhodamine B lake, Carmine 6B, etc. Cyan: Copper phthalocyanine, sulfonamide derivative dye, etc.

(3) Charge control agent 0wt% to 5wt
% Plus toner: Nigrosine-based electron-donating dyes, alkoxylated amines, alkylamides, chelates, pigments,
Quaternary ammonium salt, etc. Negative toner: Electron-accepting organic complex, chlorinated paraffin, chlorinated polyester, polyester with excess base,
Chlorinated copper phthalocyanine, etc.

(4) Examples of fluidizing agents: colloidal silica, hydrophobic silica, silicone varnish, metal soap, nonionic surfactants, etc.

(5) Cleaning agent (prevents toner filming on the photoreceptor) Examples: fatty acid metal salt, silicic acid having an organic group on the surface,
Fluorine surfactants, etc.

(6) Filler (Improvement of image surface gloss,
Reduction of raw material costs) Examples: Calcium carbonate, clay, talc, pigments, etc. In addition to these materials, a small amount of magnetic powder may be included to prevent fogging on the image surface and toner scattering. As this magnetic powder, triiron tetroxide, γ-ferric oxide, chromium dioxide, nickel ferrite, iron alloy powder, etc. with a particle size of 0.1 μm to 1 μm are used, and the content is 0.1 wt% to 5 wt%. In order to maintain clear colors, it is desirable that the content be 1 wt% or less.

[0039] Granules 100 obtained by mixing, kneading, crushing, and classifying each of the materials (1), (2), (3), and (6) above.
0 to 0.8 parts of (4) and 0 to 0.3 parts of (5) are added and mixed to obtain a toner.

Note that adhesive resins such as wax, polyolefins, ethylene vinyl acetate copolymer, and polyurethane rubber are used as resins suitable for pressure fixing toners that are plastically deformed and fixed to paper with a force of about 20 kg/cm. It will be done.

Next, the developing device according to the present invention will be explained. The developing device of the present invention is used in the developing device 17 of the above-mentioned image forming apparatus, etc., and its main structure is shown in FIG. 2, and a perspective view is shown in FIG. 3. Note that, as described above, the photoreceptor belt 10 is composed of a flexible conductive belt 10a and a photosensitive layer 10b covering the surface thereof, and the conductive belt 10a is grounded.

A developing sleeve 171, stirring screws 172, 173, a magnet roller 174, a regulating rod 175, a toner collecting roller 176, a scraping plate 177, a sealing plate 178, etc. are provided inside the developing device 17, which is a developing device. It is being

The stirring screws 172 and 173 are spiral-shaped stirring members that rotate in opposite directions, and by circulating the toner and the magnetic carrier contained in the developing device 17, they stir and mix the two. This is a member that allows That is, the two-component developer consisting of toner and carrier is thoroughly stirred and mixed while being circulated by the stirring screws 172 and 173, thereby being frictionally charged and made into a homogeneous developer, and then supplied to the developing sleeve 171. be done.

The toner is supplied to the toner supply means (not shown) when the toner concentration, which is the ratio of toner to carrier, is below a predetermined value, according to a toner concentration sensor (not shown) provided in the developing device 17. (not shown)
The toner is supplied from a toner supply port 34 provided at the end of the toner.

The developing sleeve 171 includes a magnet roller 174, and a regulating rod 175 and a toner collecting roller 176 are arranged around the developing sleeve 171. Developing sleeve 171
A constant gap (0.3 to 1 mm, preferably about 0.5 mm) is always maintained between the developing sleeve 171 and the photoreceptor belt 10 by an abutment roller (not shown) provided coaxially with the developing sleeve 171. ing. Further, it is preferable that the developing sleeve 171 is configured to move relative to the magnet roller 174, and it is particularly preferable that the developing sleeve 171 is rotated while the magnet roller 174 is fixed. In this case, the rotation of the developing sleeve 171 at the position facing the photoreceptor belt 10 is in the same direction as the conveyance direction of the photoreceptor belt 10 and is almost the same as or faster than the conveyance speed of the photoreceptor belt 10. is preferred. That is, the developing sleeve 171 is preferably rotated at a linear velocity of 1.2 to 2.0 times in the same direction as the conveyance direction of the photoreceptor belt 10 at a position facing the photoreceptor drum 10 .

The magnet roller 174 has an N pole and an S pole.
It is composed of 8 fixed magnets with equal magnetic force and poles are alternately arranged at equal intervals, and a repulsive magnetic field is formed on the downstream side of the toner collection roller 176, which will be described later, to facilitate peeling off of the carrier. In order to do this, one pole is missing, resulting in 7 poles. In this embodiment, the magnetic roller 174 composed of an eight-pole magnet is used, but in general, in order to keep the magnetic brush of the developer in the developing device low and to ensure appropriate magnetic force, A developing sleeve diameter of 8 to 20 mm, preferably 300 to 900 Gauss, and a magnetic roller of 8 to 16 poles are used. Further, in this embodiment, one pole of the magnet roller 174 is missing, but it is not necessary to have one pole missing.

The regulating rod 175 is rigid and magnetic, and is provided at a position opposite to the magnetic pole of the magnet roller 174, as shown in the figure. Further, the regulating rod 175 is pressed against the developing sleeve 171 with a predetermined load in the absence of developer, and the stirring screws 172, 17
This member forms the developer supplied from the developing sleeve 171 into a uniform thin layer of 100 to 450 μm, preferably around 300 μm. Note that the regulating rod 175 is not limited to a rod-shaped body as in the present embodiment, but may be a blade or the like as long as it can form the developer adhered onto the developing sleeve 171 into a thin layer.

The developer formed in a thin layer on the developing sleeve 171 is conveyed together with the developing sleeve 171, and forms a latent image on the circumferential surface of the photoreceptor belt 10 in the developing area at the above-mentioned developing interval. Reversal development occurs upon contact and a toner image is formed.

During this non-contact development, the bias power supply 30
A developing bias containing an alternating current component in addition to a direct current component is applied to the developing sleeve 171, and as a result, only the toner in the developer is selectively transferred (flying) from above the developing sleeve 171 to the surface of the latent image and is exposed to light. It adheres to the body belt 10. The bias power supply 30 is a power supply that applies a bias voltage between the developing sleeve 171 and the photoreceptor belt 10, and the developing sleeve 171 is connected to the bias power supply 30 and the protective resistor 3.
It is grounded via 1.

This bias power supply 30 applies a Peak-Peak voltage (VP-P) of 1.5 to the DC component of -600V.
By applying to the developing sleeve 171 an AC bias voltage with a kV and 4 kHz AC component superimposed, toner is effectively drawn from the thin developer layer on the developing sleeve 171 toward the latent image surface on the photoreceptor belt 10. supply. Note that the surface potential of the photoreceptor belt 10 is -7 in the non-exposed area.
00V, -700 to -10 depending on the amount of exposure in the exposed area
It is 0V.

The toner collection roller 176 is a member for removing only the toner from the developer remaining on the developing sleeve 171 after development,
There is always a constant gap (0.3~
1 mm, preferably about 0.5 mm). Further, it is preferable that the toner collection roller 176 is configured to move relative to the developing sleeve 17.
In particular, the rotation of the toner collection roller 176 is such that the rotation of the toner collection roller 176 is such that the rotation of the toner collection roller 176 causes the development sleeve 171 to
It is preferable that the conveying speed of the developing sleeve 171 is almost the same as that of the developing sleeve 171, or faster than that. That is, the toner collection roller 176 is preferably rotated at a linear velocity of 1.0 to 2.0 times in the same direction as the conveying direction of the developing sleeve 171 at a position facing the developing sleeve 171. The toner collection roller 176 is grounded via a bias power source 32 and a protective resistor 33, which will be described later.

After development, the developer is transferred to the photoreceptor belt 1.
Toner that has been unevenly consumed depending on the latent image of 0 remains on the developing sleeve 171 and is conveyed as the developing sleeve 171 rotates. In order to improve the efficiency of removing this residual toner, an AC bias is applied from the bias power supply 32 to the toner collecting roller 176, and as a result, only the toner in the developer remaining on the developing sleeve 171 is selectively removed. Moves onto the collection roller 176 (flying)
and adhere.

Since the bias for reverse development is applied to the developing sleeve 171, the bias power supply 32 is connected to the ground state or to the DC state via the protective resistor 33.
A state of +300 to -300V is applied when developing bias is applied.

By applying the voltage from the bias power supply 32 to the toner collection roller 176 in this manner, the toner remaining on the developing sleeve 171 is removed from the toner collection roller 176.
76 and ghosts on the developing sleeve 171 can be effectively removed.

The scraping member 177 is the toner collection roller 17
This is a member for scraping off the toner adhering to the surface of the toner collection roller 176, and is a so-called cleaning blade, scraper, etc. that is in sliding contact with the circumferential surface of the toner collection roller 176. The scraping member 17
The toner scraped off by the stirring screw 172
, 173 to mix and stir with the carrier.

After the toner components are consumed, the toner collection roller 1
Developing sleeve 171 with residual toner collected by 76
In this case, the carrier ratio of the developer on the developing sleeve 171 becomes extremely high, and a developer with a high toner ratio is mixed again, and the developer is again subjected to development.

Note that the bias power supply 30 for development performs constant current control or constant voltage control regarding the DC component and AC component, while the bias power supply 32 for toner recovery
It is preferable that constant current control is performed. Also,
The sealing member 178 is a flexible member that prevents the developer contained in the developing device 17 from spilling outside the developing device 17. Further, the bias power source 32 may use an AC bias voltage having a DC component that attracts toner to the collecting roller 176 similarly to the developing sleeve 171.

FIG. 4 is a diagram showing a configuration in which a scraper 179 is inserted into the developing device 17 shown in FIG. The developer from which the toner has been removed in advance by the collection roller 176 and which is mostly composed of carrier is scraped off by the scraper 179.
Fall. The developer such as the recovered toner and carrier is conveyed and agitated by the rotation of the screw-shaped stirring screw 172, and the toner is further supplied from the toner supply port 34 of the developing unit, and the mixed developer is transferred to the screw-shaped stirring screw 172. 173 and is fed to the developing sleeve 171. Note that this case is the same as that in FIG. 2 except that the position of the stirring screw is changed in order to facilitate the supply of developer to the developing sleeve 171.

Next, a developing device free from toner density control to which the present invention is applied will be described with reference to FIG. 5 as another embodiment. Incidentally, among the numbers in the figure, the same numbers as those in the above-mentioned embodiment have the same configuration and function as the above-mentioned developing device.

Only toner is stored in the toner container in the developing device 17, and a supply rod 17a is rotatable in the direction of the arrow within the toner container. In addition, the supply rod 17
A flexible Mylar plate 17b is provided at the tip of the toner plate 17a, and as the supply rod 17a and the Mylar plate 17b rotate, the toner contained in the toner container is sent to the toner supply roller 17c. Note that if the fed toner becomes excessive, it will overflow and be sent from above.

The toner fed by the supply rod 17a and the mylar plate 17b is transferred to the magnetic roller 174 by the toner supply roller 17c rotating in the direction of the arrow.
The toner is supplied to the developing sleeve 171 containing the toner, adheres to the carrier already attached to the circumferential surface of the developing sleeve 171, and adheres to the developing sleeve 171 as a developer.

The developer attached to the developing sleeve 171 is conveyed by the developing sleeve 171 rotating in the direction of the arrow, and is formed into a thin layer by the regulating rod 175. Furthermore, the developer in a thin layer state is transferred to the developing sleeve 1.
71, the latent image on the circumferential surface of the photoreceptor belt 10 is reversely developed in a non-contact manner in the development area, and a toner image is formed on the photoreceptor belt 10.

During this non-contact development, the bias power supply 30
A developing bias containing an alternating current component in addition to a direct current component is applied to the developing sleeve 171, and as a result, the developing sleeve 17
Only the toner in the developer No. 1 selectively moves to and adheres to the latent image surface.

After the development is completed, the developer is transferred to the photoreceptor belt 1.
Toner that has been unevenly consumed according to the latent image of 0 remains on the developing sleeve 171, and is further conveyed as the developing sleeve 171 rotates. And the developing sleeve 17
A toner collection roller 17 provided at a position spaced apart from 1.
6, an AC bias is applied to the toner collection roller 176 by the bias power supply 32, and as a result, the developing sleeve 1
Only the toner in the developer remaining on the toner collecting roller 71 selectively moves (flying) and adheres to the toner collecting roller 176,
The remaining toner is removed.

After the toner components are consumed, the toner collection roller 1
Developing sleeve 171 with residual toner collected by 76
In this case, the carrier ratio of the developer on the developing sleeve 171 becomes extremely high, and a developer with a high toner ratio is mixed again, and the developer is again subjected to development.

On the other hand, the toner adhering to the toner collection roller 176 is scraped off by a scraping member 177 that is in sliding contact with the circumferential surface of the toner collection roller 176, and is again supplied to the developing sleeve 171 by the toner supply roller 17c. be done.

In the above two embodiments, the non-contact developing method has been described, but the present invention is not limited to this, and the present invention can also be applied to a developing device using the so-called contact developing method.

[0068]

As described in detail above, the present invention provides a toner collecting roller at a position apart from the developing sleeve in the developing device, and applies an alternating electric field between the developing sleeve and the toner collecting roller to improve the development speed. The present invention provides a developing device that can later decompose and recover toner remaining on a developing sleeve from a carrier.

As a result, since it is not necessary to bring the scraper that scrapes off the developer on the developing sleeve into sliding contact with the developing sleeve, which was necessary in the conventional developing device, the torque for rotating the developing sleeve is reduced, and the developing sleeve is rotated with less torque. The burden on the sleeve driving means is reduced, and even if a scraper is provided, the degree of sliding contact is reduced, the developing sleeve does not wear out, and the durability of the developing sleeve is significantly improved. This has the effect of suppressing the deterioration of. That is, the developing device of the present invention is to provide a developing device that can remove toner on the developing sleeve without providing a scraper that is in sliding contact with the developing sleeve, and can achieve the above-mentioned numerous effects.

[Brief explanation of the drawing]

FIG. 1 is a main sectional view of an electrophotographic image forming apparatus that can be equipped with a developing device of the present invention.

FIG. 2 is a sectional view showing the main structure of the developing device according to the present invention.

FIG. 3 is a perspective view showing the main structure of the developing device according to the present invention.

FIG. 4 is a sectional view showing the main structure of the developing device according to the present invention when a scraper is used.

FIG. 5 is a sectional view showing the main structure of a developing device free of toner density control to which the present invention is applied.

FIG. 6 is a sectional view showing the main structure of a conventional developing device.

[Explanation of symbols]

17 Developing device 171 Developing sleeve 172,173 Stirring screw 174 Magnet roller 175 Regulation rod 176 Toner collection roller 177 Scraping member 179 Scraper 17a Supply rod 17b Mylar board 17c Toner supply roller

Claims (2)

[Claims] 1. A developing sleeve that performs development using an alternating electric field in a developing section using a two-component developer attached to the surface of the developing sleeve, and a developing sleeve that is located downstream of the developing section in the rotational direction of the developing sleeve. A developing device comprising: a rotating member rotatably provided at a position spaced apart from the developing sleeve, and applying an alternating current electric field between the developing sleeve and the rotating member. 2. The developing device according to claim 1, further comprising an elastic member that slides on the circumferential surface of the rotating member.