JP2000172073A - Developing device by one component toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the efficiency at the time of removal of residue toner after one component toner is carried and developed by a developing roller and the removed toner is recovered and fed again. SOLUTION: In this developing device, a feeding roller 42 is provided to come into a pressurized contact against the developing roller 41 carrying and transporting the one component toner so that it comes into contact with a photoreceptor carrying an electrostatic latent image. In addition, a recovering roller 44 is provided which is abutted to the feeding roller 42 before the feeding roller 42 and the developing roller 41 are abutted in order to eliminate the residue toner after developing in the developing range of the developing roller 41 facing the photoreceptor 1. The recovering roller 44 is driven to rotate so that it is rotated in the same direction as the other roller in ranges where it comes into contact with the developing roller 41 and the feeding roller 42, the residue toner after developing is removed by the recovering roller 44, the removed recovered toner is fed to the feeding roller 42 and this toner is fed again to the developing roller 41.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device for visualizing an electrostatic latent image formed on an electrostatic latent image carrier with a toner as a colorant, and more particularly, to a one-component toner. The present invention relates to a developing device using a developer having a configuration.

[0002]

2. Description of the Related Art In an image forming apparatus employing an electrophotographic method, such as a copying machine or a printer, an electrostatic latent image is formed on a surface of a photosensitive member which is an image carrier such as a latent image, and the electrostatic latent image is formed into a visible image. A developing device is provided which supplies a developer such as a toner as a colorant to the photoreceptor side to form an image and selectively attaches the toner.

[0003] The developing device develops the electrostatic latent image formed on the photoreceptor, and the developed toner image is transferred to a transfer material sheet or the like. Then, after the transfer, a part of the toner that has not been transferred remains on the surface of the photoconductor. The remaining unnecessary toner is also removed from the photoreceptor surface in order to repeatedly perform the next image formation. Therefore, a cleaning device that removes the toner remaining on the surface of the photoconductor after the transfer is provided, and the unnecessary toner removed by the cleaning device is stored in a storage unit in the cleaning device.

Therefore, in the image forming apparatus having the developing device as described above, the space for arranging the process means for forming an image around the photoreceptor is reduced in accordance with the miniaturization. There has been a strong demand for miniaturization.

Therefore, as a developing device, a developing device using a one-component developer, for example, a non-magnetic toner, instead of a two-component developer comprising a toner and a magnetic carrier has been proposed and put into practice. It became so. According to such a developing device using a one-component toner, compared with a developing device using a developer including a toner and a carrier,
Control of toner concentration becomes unnecessary, the mechanism for stirring the developer can be simplified, and the developing roller can be reduced in size and weight, which is excellent not only in size reduction but also in cost reduction.

Further, since there is no need to adjust the concentration of the developer and there is no carrier that is not consumed, the simplicity of maintenance and the like is excellent. In other words, there is no need to replace a deteriorated carrier with a new one,
Maintenance for the replacement is not required.

Further, it is only necessary to replenish the toner, there is no need to detect the toner density, and no control is required for that, so that the control is simplified. In particular, in a developing device using a one-component toner, it is only necessary to replenish the toner when necessary.

For example, as shown in FIG. 4, a developing device 50 for visualizing an electrostatic latent image formed on the photoconductor 1 is opposed to the photoconductor 1 as an image carrier. Are located. The developing device 50 is rotatably provided with a developing roller 51 partially exposed through an opening in a developing tank containing a toner as a one-component developer. The developing roller 51 is arranged such that a part thereof is exposed at the opening of the developing tank and comes into contact with the photoreceptor 1, for example. The contact area is a development area. Also,
The developing roller 51 may be arranged at a predetermined distance from the photoconductor 1 in some cases.

The developing roller 51 carries a one-component toner on its surface and conveys the toner to a developing area facing the photoreceptor 1. After the development, the toner not contributing to the development is transported into the developing tank and collected. In order to temporarily remove the collected toner from the surface of the developing roller 51, a supply roller 52 is provided so as to be in pressure contact with the developing roller 41, and the toner carried on the surface of the developing roller 51 is scraped off. The supply roller 52 is configured so that toner is newly supplied to the surface of the developing roller 51.

The one-component toner is supplied by the supply roller 52 and is adsorbed on the surface of the developing roller 51, and a regulating member (blade) 53 pressed against the surface of the developing roller 51 is provided to regulate the amount of adsorption. Have been. The regulating member 5
The amount of the toner that has passed through 3 is regulated to a fixed amount, reaches the developing area in contact with the photoconductor 1 as described above, and is selected according to the electrostatic latent image formed on the surface of the photoconductor 1. It will adhere to the surface and development will be performed.

Further, in order to perform development well, the developing roller 51 is supplied with a normal developing bias voltage (Va) from a power supply circuit 54. This developing bias voltage is
The voltage value is set so that toner adheres to the electrostatic latent image and toner does not adhere to the background area (background portion other than the image) of the photoconductor.

With the above configuration, the one-component developer, that is, the toner is attracted to the developing roller 51 and transported to the developing area, so that the toner adheres to the electrostatic latent image on the photosensitive member,
Therefore, adhesion of the toner to the background other than the latent image is prevented, and normal development can be performed.

Here, the toner which does not contribute to the development after the development is recovered by the rotation of the developing roller 51 as described above. At this time, if the toner is sent to the developing area again with the residual toner remaining on the developing roller 51, the toner is fused to the developing roller 51, so that a developing defect occurs and the life of the developing roller 51 is shortened. Therefore, the collected toner needs to be surely removed from the developing roller 51.

For this purpose, Japanese Patent Laid-Open Publication No. Hei 4-2955871 discloses a plate-like scraping member 55 as shown in FIG. 4, which is provided so that the tip of the scraping member 55 is pressed against the developing roller 51. The scraping member 55 is provided on the downstream side in the rotation direction of the developing roller 55 from the developing area facing the photoconductor 1. As a result, the toner remaining on the developing roller 55 after the development is removed by the scraping member 55, and new toner is supplied to the surface of the developing roller by the next supply roller 52.

FIG. 5 shows a Japanese Patent Application Laid-Open No. 63-60161.
According to the device described in Japanese Patent Application Laid-Open Publication No. H10-209, there is a device in which a rotating elastic roller 56 for removing toner is provided instead of the scraping member. The elastic roller 56 described in the above publication is rotated in opposite directions so as to be in the same direction at the contact position with the developing roller 51. As a result, the developed toner adhered to the developing roller 51 is removed.

[0016]

As described above, the structure of the scraping member 55 as the toner removing means after development having the structure shown in FIG. 4 can perform the toner removal satisfactorily. The removed toner (collected toner) cannot be efficiently reused. That is,
The toner is only scraped off, and cannot be fed to the supply roller 52, so that the toner is not circulated or reused satisfactorily and may accumulate in the lower developing tank.

On the other hand, according to the structure shown in FIG. 5, the toner after development is removed by rotation. However, in this case, the developing roller 51
The removed toner adheres to the elastic roller 56 and is not sent to the supply roller 52 as it is. In addition, after the removal, it is necessary to provide a blade 57 for removing the toner adhered to the surface of the elastic roller 56 again.

Therefore, it is necessary to separately provide a scraping blade 57, which complicates the structure. Further, since the toner is scraped off by the blade, the toner is not efficiently sent to the supply roller 52, so that the reuse efficiency is also low.

The present invention has been made in view of the above-described problems, and in a developing apparatus using a one-component toner, the removal of the toner remaining on the developer roller after development is ensured, and the efficiency of reusing the removed toner is improved. An object is to provide a developing device.

In particular, it is an object of the present invention to provide a developing device which removes toner after development adhered to a developing roller and supplies the toner to a supply roller.

[0021]

According to a first aspect of the present invention, there is provided a developing device using a one-component toner, comprising: a developing region which carries a one-component toner and faces an electrostatic latent image carrier; And a supply roller for supplying toner to the development roller, the development roller being in contact with the development roller on the downstream side of the development region of the development roller and on the upstream side of the supply roller. A collecting roller for removing and collecting the developed toner so as to be in the same direction in the contact area, and bringing the collecting roller into contact with the supply roller, and rotating the supply roller in the contact area. Characterized by being driven to rotate in the same direction as

According to the one-component toner developing device having such a configuration, the developing roller carries the toner to the area facing the image carrier and supplies the toner, so that the electrostatic latent image is visible with the toner. Image. Then, the toner not contributing to the development is collected in the developing device while being held by the developing roller. At this time, the toner is removed by a contacting recovery roller before the supply roller that supplies the toner to the developing roller.
Even if the removed and collected toner adheres to the collection roller, the toner is supplied to the supply roller because the collection roller is in contact with the supply roller. As a result, the toner collected after the development is efficiently removed by the collection roller, and the toner is continuously supplied to the supply roller. Therefore, the recovered toner is efficiently supplied to the developing roller via the supply roller together with another new toner.

Thus, the collected toner is efficiently circulated and reused without stagnation. Then, it is possible to prevent the toner attached to the developing roller from being fused and shortening the life of the developing roller.

According to the second aspect of the present invention, in the developing device for a one-component toner, the toner adhering to the developing roller is supplied with respect to the developing bias voltage Va supplied to the developing roller. It is characterized in that a bias voltage Vd in the transfer direction is supplied to the rotating roller. With such a configuration, the developed toner adhered to the developing roller is transferred to the collecting roller by a force acting electrostatically, and the removal efficiency is increased. Therefore, even if the pressure with which the collecting roller is pressed against the developing roller is weakened, a sufficient removing effect can be obtained, and the effect of fusing the toner to the developing roller can be further suppressed.

According to the third aspect of the present invention, the peripheral speed of the collecting roller is higher than the peripheral speed at which the developing roller is rotated. Thus, the effect of removing the toner adhered to the developing roller after development can be enhanced.

According to the fourth aspect of the present invention, in the one-component toner developing device having the above-described structure, the pressing force at the position where the collecting roller contacts the developing roller is reduced by the collecting roller. Is larger than the pressure contact force at the position where it contacts the supply roller. Thus, by increasing the pressure contact force with the developing roller, the effect of removing the toner adhered to the developing roller after development is naturally increased. Then, the toner removed from the developing roller contacts the next supply roller and is efficiently supplied through the supply roller. At this time, by reducing the pressing force between the supply roller and the collection roller, the supply action can be promoted, and toner can be removed and supplied more efficiently without increasing the overall drive torque. Becomes

Further, according to the invention as set forth in claim 5, in a one-component toner developing device having the above-mentioned configuration. The recovery roller is formed of an elastic member, and the elastic member is set lower than the surface hardness of the developing roller and the supply roller. According to this configuration, even when the collection roller is in contact with the developing roller and the supply roller with an appropriate pressure, the amount of heat generated due to friction and the like can be suppressed, and the action of fusing the toner to the developing roller and the like is suppressed. You.

[0028]

Embodiments of the present invention will be described below in detail with reference to the drawings. One embodiment of the developing device of the present invention will be described with reference to FIGS. FIG. 1 is a view showing a developing device according to the present invention, which is disposed opposite to a photoreceptor which is a carrier of a latent image in the image forming apparatus, and FIG. FIG. 4 is a view for explaining the principle of removing toner and supplying removed toner to a supply roller. FIG. 3 shows FIG.
1 is a configuration diagram for schematically describing the structure of an image forming apparatus provided with the developing device of the present invention shown in FIG.

First, a schematic configuration of the image forming apparatus will be described with reference to FIG. Reference numeral 1 denotes an image carrier that is disposed substantially at the center of the main body of the image forming apparatus and carries an electrostatic latent image formed in a drum shape that is driven to rotate at a constant speed in an arrow direction (S1) during an image forming operation. Photoreceptor. Various image forming process means are arranged around the photosensitive member 1 so as to face each other.

Means (apparatus) constituting the image forming process include a charger 2 for uniformly charging the surface of the photosensitive member 1, an optical system for irradiating an image 3 with light corresponding to an image (not shown), and an exposure system using the optical system. The developing device 4 according to the present invention for visualizing the electrostatic latent image formed on the surface of the photoreceptor 1 as a result, and a sheet-like image to which the developed image 10 (toner image) is appropriately conveyed. A transfer device 5 for transferring to the paper P, a cleaning device 6 for removing a residual developer (toner) not transferred to the surface of the photoconductor 1 after the transfer, and a static eliminator 7 for removing charged charges remaining on the surface of the photoconductor 1 are provided. In this order, photoconductor 1
Are arranged in the rotation direction.

The sheets P are stored in a large amount, for example, in a tray or a cassette. One sheet of the stored sheets is fed by feeding means, and the sheet P is opposed to the photosensitive member 1 on which the above-described transfer unit 5 is disposed. Is transferred to the transfer region where the toner image formed on the surface of the photoconductor 1 coincides with the leading end of the toner image. After the transfer, the sheet P is removed from the photoreceptor 1 by the action of, for example, a peeler 9 provided in parallel with the transfer unit 6 and removed from the back surface of the sheet P, and sent to the fixing device 8.

The fixing device 8 fixes the unfixed toner image transferred onto the sheet as a permanent image.
A surface opposed to the toner image is formed of a heat roller heated to a temperature at which the toner is melted and fixed, and a pressure roller or the like is provided which is pressed against the heat roller to bring the sheet P into close contact with the heat roller. It is composed. The sheet P that has passed through the fixing device 8 is discharged out of the image forming apparatus onto a discharge tray (not shown) via a discharge roller.

If the image forming apparatus is a copying machine, the optical system (not shown) irradiates a copy original with light and irradiates light reflected from the original as a light image 3. Alternatively, if the image forming apparatus is a printer or a digital copier, the optical system emits a light image obtained by driving a semiconductor laser ON-OFF according to image data. Particularly in digital copiers, image data obtained by reading reflected light from a copy original with an image reading sensor (CCD element, etc.) is input to an optical system including the semiconductor laser, and an optical image corresponding to the image data is output. I am trying to do it. In the printer, the light is converted into an optical image corresponding to image data from another processing device, for example, a word processor or a personal computer, and is irradiated. This conversion into an optical image uses not only a semiconductor laser but also an LED element, a liquid crystal shutter and the like.

As described above, when the image forming operation in the image forming apparatus is started, the photosensitive member 1 is driven to rotate in the direction of the arrow, and the surface of the photosensitive member 1 is uniformly charged to a specific polarity by the charger 2. You. After this charging, the optical image 3 is irradiated by the above-described optical system (not shown), and an electrostatic latent image corresponding to the optical image is formed on the surface of the photoconductor 1. In order to visualize the electrostatic latent image, the electrostatic latent image is developed by a developing roller 41 included in the developing device 4. In the present invention, this development is development with one-component toner, and the toner is selectively attracted to an electrostatic latent image formed on the surface of the photoreceptor 1 by, for example, electrostatic force, and development is performed. Here, a portion surrounded by a broken line in FIG. 3 corresponds to the developing region 46.

The toner image on the surface of the photoreceptor 1 thus developed is electrostatically transferred onto a sheet P conveyed appropriately in synchronization with the rotation of the photoreceptor 1 by a transfer unit 5 disposed in a transfer area. Transcribed. In this transfer, the transfer device 5 charges the back surface of the sheet P with the polarity opposite to the charging polarity of the toner, thereby transferring the toner image to the sheet P side.

After the transfer, a part of the untransferred toner image remains on the surface of the photoconductor 1, and the residual toner is removed from the surface of the photoconductor 1 by the cleaning device 6.
The surface of the photoreceptor 1 is neutralized by the neutralizer 7 to a uniform potential, for example, substantially zero potential in order to reuse.

On the other hand, the sheet P after the transfer is peeled off from the photoreceptor 1 by the action of the peeler 9 and is conveyed to the fixing device 8. In the fixing device 8, the toner image on the sheet P is melted, and is pressed and fused to the sheet P by a pressing force between rollers. The sheet passing through the fixing device 8 is discharged as a sheet P on which an image has been formed to a discharge tray or the like provided outside the image forming apparatus.

(One Embodiment of Developing Device of the Present Invention) Next, the structure of the developing device of the present invention will be described with reference to FIG. That is, a configuration example of the developing device using one-component toner of the present invention will be described in detail.

First, referring to FIG. 1, the structure of a developing device for developing with one-component toner will be described. The developing device 4 is provided in a developing tank 40 containing a one-component toner, for example, a non-magnetic one-component toner. And a supply roller 42 for supplying one-component toner to the developing roller 41 side.

The developing roller 41 provided in the developing tank 40 is partially exposed through the opening of the developing tank 40 and is used for transporting the toner to the developing area 46 facing the photosensitive member 1 described above. Are provided so as to be rotated in the same direction in a development area facing the photoconductor 1. The supply roller 42 described above is pressed against the development roller 41 at a position opposite to the development area.

The developing roller 41 has a structure in which, for example, the surface of a metal roller (including a rotating shaft) is coated with a porous elastic material such as a sponge. If an elastic body such as a sponge is made of a polymer foamed polyurethane or the like in which carbon is dispersed, or an ion conductive solid rubber is used, a predetermined resistance value that does not cause toner fusion or the like can be maintained. , As described later, it works effectively when the developing bias voltage is supplied.

The developing roller 41 is connected with a drive motor (not shown), and is shown in the direction of the arrow (S3) in the figure.
Is driven to rotate. The one-component non-magnetic toner is attracted to the surface of the rotating developing roller 41 and is transported to the developing area 46 facing the surface of the photoconductor 1. Since the developing roller 41 is pressed against the surface of the photoconductor 1, the pressed area becomes the developing area 46, and the one-component toner is attracted to the electrostatic latent image on the surface of the photoconductor 1 and developed. become.

The one-component toner is a non-magnetic one-component toner, for example, a styrene-acryl copolymer 80 to
A material having a composition of 90 parts by weight, 5 to 10 parts by weight of carbon black, and 0 to 5 parts by weight of a charge controlling agent is mixed, kneaded, pulverized, and classified to obtain a negatively charged toner having an average particle size of about 5 to 10 μm. Obtainable. To this toner, 0.5 to 1.5 parts by weight of silica (SiO ₂ ) added internally or externally to improve the fluidity is added to obtain a non-magnetic one-component toner.

The toner is not limited to negatively charged toner, but may be positively charged toner. This can be easily obtained by appropriately selecting a binder resin, a charge control agent, and the like as main components. Further, the toner is not covered with black toner for monochrome copying machines and printers, but can be applied to color toners for color copying machines and printers.

Further, the non-magnetic one-component toner is not limited to the above-mentioned composition material, and can be used in the developing device of the present invention even if it has the following composition.

The thermoplastic resin, which is the binder resin as the main component, may be polystyrene, polyethylene, polyester, low molecular weight polypropylene, epoxy, polyamide, polyvinyl butyral, or the like, in addition to the styrene-acrylic copolymer.

As the coloring agent, in the case of a black toner, there are furnace black, nigrosine dyes, metal-containing dyes and the like in addition to the above-mentioned carbon black. For color toners, benzidine yellow pigment for yellow, phonon yellow, anilide acetoacetate insoluble azo pigment, monoazo pigment, azomethine dye, etc., xanthene magenta dye for magenta, phosphotungsten molybdate lake pigment, anthraquinone Dyes, coloring materials comprising xanthene dyes and organic carboxylic acids, thioindigo, naphthol-based insoluble azo pigments, and the like, and copper phthalocyanine-based pigments for cyan.

Further, in addition to, for example, silica as an external additive used as a fluidizing material of the toner, colloidal silica, titanium oxide, alumina, zinc stearate, polyvinylidene fluoride, and a mixture thereof may be used.

Further, as the charge control agent, azo-based metal-containing dyes, organic acid metal complex salts, chlorinated paraffins and the like can be used for negatively charged toners. For positively charged toners, nigrosine dyes, fatty acid metal salts, amines, quaternary ammonium salts, and the like can be used.

The developing bias voltage Va is supplied from the developing bias power supply circuit 11 to the developing roller 41 that performs development using the one-component toner having the above-described configuration. The developing bias voltage Va is set to a polarity and a voltage value so that toner adheres to the electrostatic latent image formed on the photoconductor 1 and toner does not adhere to other areas, that is, non-image areas.

The supply roller 42 rotates in a direction opposite to the developing roller 21 (pressure contact area).
The direction (S) shown in FIG.
It is rotationally driven in 2). The supply roller 42 uses the same material as the developing roller 41, and the electric resistance can be adjusted with the same resistance adjusting material as the developing roller 41. In order to further increase the elasticity of the supply roller 42, a foamed material is used, and a foaming agent having a larger amount than the developing roller is used.

A bias voltage Vc is applied to the supply roller 42 from the bias power supply circuit 12. In general, the toner is pressed (moved) toward the developing roller 41, that is, the toner on the supply roller 42 side is discharged. The bias voltage is set to the direction in which the repulsion is supplied to the developing roller 41. For example, when a negative polarity toner is used, a larger bias voltage Vc is applied to the supply roller 42 on the negative polarity side.

The developing roller 41 and the supply roller 42 are connected to a drive motor (not shown), and are driven to rotate in the direction of the arrow in FIG. The toner remaining on the surface of the developing roller 41 that has not contributed to the development is peeled (removed). The toner supplied by the supply roller 42 adheres to the surface of the developing roller 41, and the photosensitive member 1
Before being conveyed to the developing area facing the front surface, the blade 43, which is a member for appropriately regulating the amount of toner adhering to the developing roller 41, regulates the amount of adhered toner and regulates the toner layer thickness to a constant value. are doing.

The blade 43 is pressed against the developing roller 41 with an appropriate pressure. The blade 43 is formed of a blade component or the like made of a plate-like metal material,
The antinode (surface) portion near the front end is pressed against the developing roller 41. Therefore, the toner supplied to the developing roller 41 is regulated to a predetermined charge amount and a predetermined thickness by a predetermined set pressure and a set position of the blade 43, and is conveyed to a developing region which is in opposing contact with the photoconductor 1.

The blade 43 as the regulating member is provided such that one end is fixed to the developing tank 40 side and the other end of the free end side is pressed against the surface of the developing roller 41 by elastic deformation having spring property. Have been. The blade 43 is made of, for example, a metal plate such as phosphor bronze or stainless steel (SUS) having a thickness of about 0.05 to 0.5 mm. Along the rotation axis direction) is pressed against the antinode portion near the tip. Thereby, the developing roller 4 is
The amount of the one-component toner carried on one surface via the supply roller 42 is made constant, and the toner is conveyed to a developing area in contact with the photoconductor 1.

The blade 43 having a spring property made of metal is
Spring steel such as SUP, SUS301, S
Stainless steel such as US304, SUS420J2, SUS631, etc., C1700, C1720, C5210, C7
The same alloy such as 701 can be used. And
The tip of the blade 43 that contacts the developing roller 41 has a surface slightly inclined in a direction away from the developing roller 41. For this reason, the inclined surface of the blade 43 may be mechanically cut, polished, or bent, or a tip-shaped tip formed and processed into a desired shape may be attached with a conductive adhesive or the like, or a step may be formed on the blade tip. It is manufactured by a processing method such as applying a metal foil from there over with a conductive adhesive or the like.

Also in the blade 43 having such a configuration, a predetermined voltage Vb is supplied from the bias power supply circuit 13. Also in the bias voltage Vb, a larger value is set in the direction in which the toner is pushed from the blade 43 toward the developing roller 41, for example, in the case of negative polarity toner, on the negative polarity side. Further, the bias voltage Vb supplied to the blade 43 may be set to the same potential as the developing bias voltage Vb supplied to the developing roller 41, or to a value larger in absolute value.

On the other hand, the toner conveyed to the developing area facing the photoreceptor 1 is selectively attached according to the electrostatic latent image formed on the surface of the photoreceptor 1, and the electrostatic latent image is formed by the color of the toner. Visualize. Then, the toner that has not contributed to the development is returned into the developing tank 40 by the rotation of the developing roller 41. The return position, that is, the photosensitive member 1 and the developing roller 4
1 is located on the downstream side in the rotation direction of the developing roller 41 from the developing region where the developing roller 41 contacts, and the supply roller 42 and the developing roller 41
A collection roller 44 constituting a toner charge elimination unit is provided on the upstream side of the position where the contact roller contacts with the developing roller 41 so as to be pressed against the developing roller 41. The collection roller 44 is disposed at a position where the supply roller 42 contacts the developing roller 41, that is, at an upstream side in the rotation direction of the developing roller 42.
In order to appropriately press the developing roller 41 against the developing roller 41, the developing roller 41 is rotationally driven in the direction of the arrow (S5) in FIG.

The collecting roller 44 is formed by coating a stainless steel rotating shaft with elastic rubber in order to remove the toner more efficiently than the developing roller 41, and a bias voltage for attracting the toner of the developing roller. Vd is supplied from the power supply circuit 14 to the shaft portion.

Here, the feature of the present invention will be described. The collecting roller 44 is not only provided in pressure contact with the developing roller 41 as shown in FIG.
It is also provided so as to be in pressure contact with the supply roller 42 that supplies the toner to the supply roller 1. In addition, the rotation direction of the collection roller 44 is the same in the position where it is in pressure contact with the developing roller 41, and is also the same direction in the position where it is in pressure contact with the supply roller 42. I have.

The photoreceptor 1 has an underlayer coated on the surface of a metal or resin conductive substrate, a carrier generation layer (CGL) as a layer thereon, and a carrier containing polycarbonate as a main component on the outermost layer. An OPC photoreceptor formed by applying a moving layer (CTL) is used. In the present invention, the present invention is not limited to such a photoreceptor, but may be any carrier that carries an electrostatic latent image.

As described above, the developing device 4 conveys the toner to the area facing the photoconductor 1 and visualizes the electrostatic latent image on the surface of the photoconductor 1. As described above, the toner image on the surface of the photoconductor 1 is transferred to the sheet P appropriately conveyed in the transfer area by the operation of the transfer device 5, and the sheet P is discharged by the operation of the peeling device 9. Then, the toner image is peeled off from the surface of the photoconductor 1, passes through the fixing device 8, and is discharged out of the image forming apparatus.

In the developing device 4, toner remains on the developing roller 41 that has not contributed to the development after the development, and the residual toner is removed by the collecting roller 44 before reaching the position of the supply roller 42. The removed toner adheres to the supply roller 42 side by the collection roller 44 and is sent, and comes into contact with the supply roller 42. for that reason,
The toner is removed from the collecting roller by the supply roller 42, supplied to the supply roller 42 including other toner, and supplied again to the developing roller 41 including new toner.

The flow of supplying the developed toner to the developing roller 41 again as described above will be described in further detail with reference to FIG. In FIG. 2, at a contact position between the developing roller 41 and the collecting roller 44, the respective rollers are driven to rotate in the same direction. By this rotation, the toner adhering to the developing roller is removed by the rotating collecting roller 44. Then, the toner removed by the collection roller 44 is re-supplied at a position where the toner is next contacted with the supply roller 42,
This is supplied to the developing roller 41.

Here, if the rotation direction of the collection roller 44 is the same as the rotation direction of each of the developing roller 41 and the supply roller 42, that is, they are driven to be opposite to each other at the contact position, the toner adhering to the Although the removing effect is enhanced, the effect of removing the toner from the supply roller 42 is also enhanced. Therefore, the supply of the collected toner from the collection roller 44 to the supply roller decreases, and the supply roller 42
, The efficiency of supply to the developing roller 41 is greatly reduced.
Therefore, by rotating the collecting roller 44 as shown in FIG. 1, the effect of removing the toner from the developing roller 41 and supplying the removed toner to the supply roller 42 as shown in FIG. The efficiency of recycling is increased.

Further, it is not necessary to provide a special blade for removing the toner on the collection roller 44, and the supply roller 42
, It is possible to efficiently supply the recovered toner.

Next, in the developing device according to the above-described embodiment of the present invention, the relationship between the bias voltage Vd supplied to the collection roller 44 and the speed at which the collection roller 44 is rotated is further improved in other embodiments, particularly. An embodiment of efficient toner collection and resupply will be described.

(Other Embodiments of the Present Invention) The developing roller 41 is as described above, but the structure thereof will be described in more detail. The developing roller 41 is made of, for example, a conductive urethane having a volume low efficiency of about 10 ⁶ Ωcm and a JIS-A hardness of 60 to 70 degrees in which a conductive agent such as carbon black is added to an 18 mm shaft 41 a made of stainless steel such as metal. A rubber-coated conductive roller having a diameter of 34 mm is formed. The surface roughness Rz of the roller 41 is Rz
= 3 to 6 μm (according to JISB-0601). The developing roller 41 is pressed against the photoreceptor 1 with a contact depth of 0.1 mm to 0.3 mm via a toner layer, and has a peripheral speed of 2 through a driving motor (not shown) in the direction of the arrow.
It is driven to rotate at 85 mm / sec.

The developing roller 41 is supplied with a developing bias voltage Va of the developing bias power supply 11 and a developing bias voltage of -450 V, for example, when the charging characteristic of the one-component toner is negative, to the shaft 41a.

The recovery roller 44 for removing the toner remaining after the development of the developing roller 41 is driven to rotate in the direction shown in FIG. 1 while the developing roller 41 is pressed.
This collection roller 44 has a surface tank made of an elastic rubber,
It is driven to rotate at a peripheral speed of 300 mm / sec.
And, as the bias voltage Vd from the power supply circuit 14,
A voltage of 200 V is supplied so that the collected toner after the development is neutralized and collected at the same time.

With such a configuration, the negatively charged toner adhering to the developing roller 41 after the development is discharged at a position where it contacts the collection roller 44 in one minute, and is supplied to each of them. In the relationship between the bias voltages Va and Vd, the material is drawn toward the collection roller 44, and the collection, that is, the removal efficiency is further enhanced. This is also because an electrostatic force acts on the negatively charged toner to transfer to the collection roller 44 having a lower potential than the developing roller 41.

Therefore, as described above, the potential at which the toner easily moves to the collection roller 44 side is set to the collection roller 4.
4 is supplied, and the value is not limited to the value exemplified above. That is, the bias voltage Vd supplied to the collection roller 44 changes with the bias voltage Va supplied to the developing roller 41 depending on the charging polarity of the toner. However, the absolute value of | Va |> | Vd | is maintained. By doing so, the efficiency of removing the toner increases.

The peripheral speed of the collecting roller 44 is set higher than the peripheral speed of the developing roller 41. For example, in the above example, the peripheral speed of the developing roller 41 is 285 mm / sec, and the peripheral speed of the collection roller 44 is 300 mm / sec. Therefore, the toner adhering to the developing roller 41 is removed by the collecting roller 44 having a high rotation speed,
The removal efficiency increases. That is, since the speed of the collecting roller 44 is high, the contacting collecting roller 44 is
Since the next region comes further away and comes into contact with the developing roller 41, the toner removing effect is further enhanced.

Therefore, the peripheral speed of the collection roller 44 is
By setting the peripheral speed higher than the peripheral speed of the developing roller 41, the toner removing efficiency is further increased. This is of course further increased by simultaneously using the relationship between the bias voltages Va and Vd described above.

On the other hand, in order to increase the efficiency of supplying the toner removed by the collection roller 44 to the developing roller 41 via the supply roller 42 again, the structure of the supply roller 42 will be further described. , Developing tank 4
The function also serves to agitate the toner within 0 and remove the residual toner after development by the developing roller 41 from the developing roller 41. The supply roller 42 is configured by covering a rotating shaft 42a thereof with a conductive porous foam member.

The porous foam is made of conductive urethane foam having a volume efficiency of 10 ⁵ Ωcm, a porous cell density of 80 to 140 cells / inch, and an Asuka F hardness of 60 to Asuka C hardness of 30 degrees. This polyurethane foam is mixed with carbon black in an amount of 5 to 15 parts by weight, and in some cases, about 70 parts by weight based on 100 parts by weight of the foam. The same polyurethane foam and carbon black as those used for the developing roller 41 are used.

In order to obtain a foam which forms the above-described cell density, for example, a polyurethane foam and carbon black are mixed, stirred by a whisk, and whisked, and then heated and blow-formed to form a metal (same as the developing roller 41). (Structure) to cover the circumference of the rotating shaft 42a having a diameter of 8 mm and a diameter of 20 m
m of supply rollers 42 are formed.

The supply roller 42 is pressed against the developing roller 41 to a contact depth of about 0.5 mm to 1 mm, and has a peripheral speed of 170 mm via a drive motor (not shown) in the direction of the arrow.
Is driven to rotate. The supply roller 42 is supplied with, for example, −550 V as a voltage Vc from the toner supply bias power supply 12 to a shaft 42 a made of stainless steel.

The blade 43 serving as a regulating member was made of a stainless steel plate having a thickness of about 0.1 mm, and was pressed against the developing roller 41. In particular, the blade 43 has a cantilever plate spring structure, and its free end side is brought into contact with the developing roller 41 and is elastically deformed to apply a predetermined pressure to the toner layer on the surface of the developing roller 41. This blade 4
3 is also supplied with −500 V as a bias voltage (Vb) from the power supply circuit 13.

Here, in order to efficiently remove the toner adhered to the developing roller 41, the peripheral speed of the collecting roller 44 is set to be sufficiently higher than the peripheral speed of the developing roller 41. . However, the collection roller 44 needs to contact the supply roller 42 and supply the removed and collected toner to the supply roller 42 side. Therefore, it is important to increase the speed more than necessary from the viewpoint of reuse in view of the relationship with the peripheral speed with the supply roller 42.

That is, the supply roller 42 and the developing roller 41
That is, in the supply area, that is, in the contact area, the toner is rotationally driven so as to be in opposite directions to each other so as to increase the toner supply efficiency. Therefore, the peripheral speed of the supply roller 42 is set lower than that of the developing roller 41. As a result, when the peripheral speed of the collection roller 44 is increased, the supply roller 42
Is further increased, and the efficiency with which toner is supplied from the collection roller 44 to the supply roller 42 is reduced.

Therefore, in order to maintain the efficiency of removing the residual toner adhering to the developing roller 41, the collecting roller 4
The peripheral speed of No. 4 is 290 to 320 mm based on the above example.
/ Sec. This is the developing roller 4
This corresponds to the peripheral speed of 285 mm / sec, which is about 5 (± 3)% of the peripheral speed of the developing roller 41, and the peripheral speed of the collection roller 44 may be increased accordingly. For example, the peripheral speed of the collection roller 41 is 340 mm / s
When the value of ec is increased, the peripheral speed of the supply roller 42 becomes twice or more, the toner of the supply roller 42 is removed from the collection roller, and efficient supply cannot be performed.

(Other Embodiments of the Present Invention) As described above, in one embodiment of the present invention, the collection roller 44
The relationship between the rotation direction, the contact state between the developing roller 41 and the supply roller 42, the peripheral speed and the bias voltage to be supplied was described, and the point of improving the toner removal and supply state was described.

The conditions for improving the efficiency of toner removal and recovery and the supply of the toner are not limited to those described above, and other conditions may be appropriately set.
The toner collection efficiency can be improved, and this will be described below.

In order to enhance the toner removing effect, the efficiency is greatly affected not only by the bias voltage, the rotational direction and the peripheral speed, but also by the pressing force between the collecting roller 44 and the developing roller 41 as described above.

However, the developing roller 41 of the collecting roller 44
If the pressing force is increased, the removal efficiency is increased, but the overall drive torque in the drive system is significantly increased. Further, when the recovery roller 44 is pressed against the supply roller 42, it is necessary to supply the recovered toner to the supply roller 42 side. By reducing the pressure contact force, the supply efficiency can be increased.

Therefore, considering the entire driving torque,
By making the pressing force of the collecting roller 44 against the developing roller 41 stronger than the pressing force of the supplying roller 42, the effect of removing the toner can be enhanced, and the effect of supplying the toner to the supplying roller 42 can be enhanced. That is, the collection roller 44
The pressing force against the developing roller 41 is increased so that the driving torque becomes the same as the entire driving torque when the pressing state between the developing roller 41 and the supply roller 42 is the same. Set to weaken. Thus, even if the entire driving torque is set to be the same, the effect of removing the toner from the developing roller 41 can be enhanced, and the supply efficiency of the toner supply roller 42 can be increased.

As described above, by setting the pressure contact state of the collection roller 44 in a magnitude relationship from the relationship between the developing roller 41 and the supply roller 42, the effect of achieving the object of the present invention is further enhanced. In addition, by setting the relationship between the above-described bias voltage and the peripheral speed including this relationship, the effect is further enhanced.

For example, when the bias voltage is set, the toner removing effect is enhanced, and it is not necessary to increase the force of pressing the collecting roller 44 against the developing roller 41 more than necessary. The toner removing effect can be expected, and the driving torque can be reduced as a whole.

As described above, the collection roller 44
It is pressed against the developing roller 41 and the supply roller 42.
Therefore, when the hardness of the collection roller 44 is equal to or higher than the hardness of the developing roller 41 and the supply roller 42,
It is conceivable that friction occurs due to a difference in peripheral speed or the like in each contact area, and the fusion heat causes toner fusion or the like. Therefore, if the pressing force is reduced, the fusion of the toner due to the frictional heat can be reduced, but the effect of removing and supplying the toner is reduced as described above.

Therefore, the hardness of the elastic rubber of the collection roller 44 is made smaller than at least the hardness of the elastic rubber of the developing roller 41. Further, the hardness of the collection roller 44 is made smaller than the hardness of the elastic rubber of the supply roller 42. This allows
Damage such as friction at the contact position of the collection roller 44 with the developing roller 41 and the supply roller 42 can be reduced, and toner fusion and the like can be suppressed. The life of the developing roller 41 and the supply roller 42 can be extended by fusing the toner.

Here, the above-described developing device 4 has been described in the case of developing with a single color, especially with a black toner. In the present invention, since a non-magnetic one-component toner is used, it is not necessary to include magnetism in a magnetic toner or the like. As a result, it is possible to easily obtain toners of cyan, magenta and yellow qualities, and to perform development using these toners. Therefore, by using the toner of four colors and using it as a developing device for superimposing the toners of these colors, it is possible to reproduce a color image of high quality.

[0093]

According to the developing device using one-component toner of the present invention, the toner remaining after developing on the developing roller for developing can be recovered and efficiently reused. For this reason, residual toner remains on the developing roller as it is, and development failure when contributing again to development can be suppressed, and a reduction in the life of the developing roller due to toner fusion or the like can be eliminated.

Further, the present invention can achieve the object with a simple configuration without providing any special means for removing the toner and resupplying the removed collected toner.

Further, by arbitrarily setting a bias voltage, a rotation speed (peripheral speed), and the like to be supplied to the collection roller for removing the toner, the removal efficiency of the toner is improved, and the supply efficiency for reuse is improved. Becomes possible.

In addition, by considering the pressing state of the recovery roller and the hardness of the developing roller and the like, the life of the developing roller and the toner removing efficiency can be further improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of a developing device using one-component toner for describing an embodiment according to the present invention.

FIG. 2 is a diagram for explaining a flow of removing toner from a developing roller constituting the developing device shown in FIG. 1 and re-supplying the removed collected toner.

FIG. 3 is a configuration diagram schematically illustrating an overall structure of an image forming apparatus including the one-component toner developing device of the present invention illustrated in FIG. 1;

FIG. 4 is a diagram illustrating an example of a conventional developing device.

FIG. 5 is a diagram showing another example of a conventional developing device.

[Description of Signs] 1 Photoconductor (electrostatic latent image carrier) 4 Developing device 10 (Non-magnetic) one-component toner 11 Power supply circuit for supplying developing bias voltage Va to developing roller 13 Voltage Vc to supplying roller Supply voltage circuit 14 Power supply circuit for supplying bias voltage Vd to collection roller 40 Developing tank 41 Developing roller 42 Supply roller 43 Blade (regulating member) 44 Collection roller

Continuing on the front page (72) Inventor Hiroshi Tatsumi 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka Inside (72) Inventor Takayuki Yamanaka 22-22 Nagaikecho, Abeno-ku, Osaka-shi, Osaka F term (reference) 2H077 AC04 AC16 AD02 AD06 AD13 AD23 AD31 AD35 CA19 EA14 EA15 FA22 GA13

Claims (5)

[Claims] 1. A developing device comprising: a developing roller that carries a one-component toner and transports it to a developing area facing an electrostatic latent image carrier; and a supply roller that supplies toner to the developing roller. A collection roller is provided downstream of the development region of the roller and upstream of the supply roller, for contacting with the development roller and removing and collecting the developed toner so as to be in the same direction in the contact region, A one-component toner developing device, wherein a collection roller is also brought into contact with the supply roller, and is driven to rotate in the same direction as the supply roller in the contact area. 2. The method according to claim 1, wherein a bias voltage Vd in a direction in which toner adhering to the developing roller is transferred with respect to the developing bias voltage Va supplied to the developing roller is supplied to the rotating roller. A developing device for a one-component toner according to claim 1. 3. The one-component toner developing device according to claim 1, wherein the peripheral speed of the collecting roller is higher than the peripheral speed at which the developing roller is rotated. 4. A pressing force at a position where the collecting roller contacts the developing roller is larger than a pressing force at a position where the collecting roller contacts the supply roller. A one-component toner developing device. 5. The one-component toner according to claim 1, wherein the recovery roller is formed of an elastic member, and the elastic member is set lower than the surface hardness of the developing roller and the supply roller. Developing device.