JP3495653B2 - One-component toner developing device - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device in which an electrostatic latent image formed on an electrostatic latent image carrier is visualized with a toner which is a colorant, and in particular, one component is used as the toner. The present invention relates to a developing device that uses a developer having a configuration.

[0002]

2. Description of the Related Art An image forming apparatus employing an electrophotographic system such as a copying machine or a printer forms an electrostatic latent image on the surface of a photoconductor which is an image bearing member carrying a latent image or the like. A developing device is provided which supplies a developer such as a toner, which is a colorant, to the photoconductor side in order to form a visible image, and selectively adheres the toner.

The developing device develops the electrostatic latent image formed on the photoreceptor, and the developed toner image is transferred to a sheet or the like as a transfer material. After the transfer, a part of the toner that could not be transferred remains on the surface of the photoconductor. The remaining unnecessary toner is removed from the surface of the photoconductor in order to repeat the next image formation. Therefore, a cleaning device for removing the toner remaining on the surface of the photoconductor after the transfer is provided, and the unnecessary toner removed by the cleaning device is accommodated in the accommodating portion 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 photoconductor is narrowed in response to the downsizing of the image forming device. Also, there is a strong demand for miniaturization.

Therefore, as a developing device, a developing device using a one-component toner without using a two-component developer comprising a toner and a magnetic carrier has been proposed and put into practice. . In the developing device using such a one-component toner, it is not necessary to control the toner concentration, and the volume of the developing tank can be significantly reduced because there is no carrier, and therefore the developing device can be downsized. . In accordance with this, the ease of maintenance and the like is also excellent. In other words, since it is not necessary to replace the deteriorated developer, especially due to the deterioration of the carrier, the maintenance for the replacement is unnecessary.

Further, since it is only necessary to replenish the toner, it is not necessary to detect the toner density, and the control for that is not required, so that the control is simplified. In particular, in a developing device using a one-component toner, it suffices to replenish the toner when necessary.

For example, as shown in FIG. 7, a developing device 4 for visualizing an electrostatic latent image formed on the photoconductor 1 is opposed to the photoconductor 1 which is an image carrier. It is arranged. The developing device 4 includes a toner 1 which is a one-component developer.
The developing roller 41 is rotatably provided so as to face the opening of the developing tank 40 containing 0. The developing roller 41 is partially exposed at the opening of the developing tank 40,
For example, it is arranged so as to be in contact with the photoconductor 1. This contacting area becomes the developing area.

The developing roller 41 carries one-component toner on its surface and conveys it to a developing area facing the photoconductor 1. After the development, the toner that has not contributed to the development is conveyed into the developing tank 40 and collected. In order to remove the collected toner from the surface of the developing roller 41 once, a supply roller 42 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 41 is scraped off. Then, the supply roller 42 is configured to newly supply the toner to the surface of the developing roller 41.

The one-component toner is supplied by the supply roller 42 and adsorbed on the surface of the developing roller 41, and a regulating member 43 pressed against the surface of the developing roller 41 is provided in order to regulate the adsorption amount. . The amount of toner that has passed through the regulating member 43 is regulated to a certain amount, and reaches the developing area in contact with the photoconductor 1 as described above, and becomes an electrostatic latent image formed on the surface of the photoconductor 1. Selectively adheres accordingly,
Development will be performed. A developing device having such a structure is proposed in, for example, Japanese Patent Laid-Open No. 3-33776.

Therefore, as the regulating member 43, there is a member having a plate shape and provided so as to be brought into pressure contact with the developing roller 41, instead of the roller structure shown in FIG. In such a configuration, the life of the plate-shaped regulating member 43 is determined by the degree of progress of wear of the contact portion that contacts the developing roller 41. This contact portion is the developing roller 4
When 1 rotates, it comes into sliding contact with the developing roller 41 and wears due to this contact. When this wear progresses and the contact portion becomes unusable, the life of the regulating member 43 is reached. In the leaf-spring-shaped regulating member 43, only a specific portion having a fixed contact portion is always in contact with the peripheral surface of the developing roller 41 and rubbed, and the contact portion remains unchanged, resulting in remarkable wear.

If a plate-like member is used as the regulating member 43, the structure can be simplified and the cost can be reduced. However, as described above, the contact portion with the developing roller 41 is significantly worn as described above. Become. Moreover, the regulation member 43
The toner sticking easily occurs at the contact portion with the developing roller 41. When the toner is fixed, the amount of the developing roller 41 adhered to that portion is different from that of the other portion, which is very thin, and a large amount of the toner partially adheres to destroy the uniform toner layer thickness state. This results in white streaks and black streaks due to development.

Therefore, there is a problem that the life of the regulating member 43 is shortened due to the above-mentioned problems caused by the abrasion and the toner adhesion.
Therefore, in the related art, the regulation member 43 has a roller structure as shown in FIG. 7, so that toner adhesion can be reduced and life can be extended without fixing the contact portion with the developing roller 41.

If the regulating member 43 is constituted by a roller, the amount of toner adhering to the developing roller 41 is naturally stable, and unevenness of the toner charge amount can be favorably prevented, so that there is an effect of more stable development. However, even if the regulating member has a roller structure, it is conceivable that the fixing of the toner will not be eliminated, but that the fixing will be caused by long-term use.

Therefore, in Japanese Patent Laid-Open No. 2-116872, a member for cleaning the regulating member 43 having a roller structure is provided to remove the toner once attached to the regulating member 43. As the cleaning member, the tip of the plate-shaped member 49 is strongly pressed against the roller surface to forcibly scrape off the toner adhering to the surface of the regulating member 43.

[0015]

As described above, in the case of the roller-constituting regulating member 43, the contact portion with the developing roller 41 is not always fixed, so that toner adhesion or the like is reduced. Further, by providing the cleaning member 49, toner adhesion can be eliminated.

However, when the toner is scraped off by the cleaning member, the pressure contact condition with the regulating member becomes a problem, and its adjustment and the like becomes very troublesome. In particular, if the pressure contact force is increased, the effect of scraping off the toner is increased, but the regulation member 4
3 becomes a problem, causing a problem of life due to scratching or the like.

In particular, in order to surely remove the toner adhering to the regulation member by the cleaning member, it is necessary to press the tip of the cleaning member so as to strongly dig into the regulation member 43. If the position of the tip is displaced or the tip is formed irregularly, the damage of the regulating member becomes a serious problem. As a result, the regulation state of the toner by the regulation member becomes unstable.

The amount of toner carried on the current image roller 41 as described above, i.e. be formed in the regulating member and the plate and the roller-shaped regulating the layer can not solve the problem of the life of the regulating member. Regarding the toner adhesion between the regulating member and the developing roller, if the regulating member has a roller structure,
Although it is alleviated, the problem of providing the cleaning member 49, that is, the above-mentioned service life cannot be solved.

Further, the developing roller 41 and the roller 43, which is a regulating member, are rotated during the developing operation, and the contact portions that are pressed against each other are not always fixed. However, when the development is completed, the rotation of the developing roller is stopped and the regulating roller 43 is stopped at the same time. At this time, the toner is interposed between the developing roller and the regulation roller, and there is a fear that the interposed toner is fixed by an appropriate pressure. However, heretofore, the defect due to such a matter has not been considered at all.

In view of the above-mentioned problems, the present invention has a roller structure as a regulating member that regulates the amount of toner adhered to the developing roller in a developing device using a one-component toner, and does not damage the toner without damaging it. An object of the present invention is to provide a developing device that eliminates the occurrence.

Another object of the present invention is to prevent toner from sticking after development, and to prevent toner sticking by performing a post-treatment after development.

[0022]

A developing device using a one-component toner according to the first aspect of the present invention for achieving the above-mentioned object according to the present invention is a developing area for carrying a one-component toner and facing an electrostatic latent image carrier. A developing roller that has a developing roller that conveys the toner to the developing area, and the regulating roller that regulates the amount of toner that adheres to the developing roller before the developing roller conveys the toner to the developing area. In the apparatus, in response to the completion of the developing operation of the developing device, the rotation of the regulating roller is continued, and the potential difference between the developing roller and the regulating roller is opposite to the potential difference during the developing operation, and the toner is regulated by the regulating roller. It is characterized in that a control unit is provided, which switches and controls the voltage value supplied to the regulation roller so that the value is pulled toward the side.

According to the developing device having such a structure, the regulating roller is provided so that the amount of the one-component toner adhered to the developing roller can be regulated to a predetermined amount, and the same portion is not always contacted. To be rotated. Therefore, it is possible to prevent the life from being shortened due to abrasion or the like. Further, the developing roller and the regulation roller are stopped after the development, and in order to prevent the toner interposed therebetween from being fixed by pressure or the like, the regulation roller is continuously driven to rotate, and at the same time, the toner is moved to the regulation roller side. Since the switching control is performed according to the relationship of the potential difference that attracts the toner, the toner attached and remaining on the developing roller side, in particular, the toner at the position in contact with the regulation roller is scraped off. Therefore, even if the rotation of the regulation roller is stopped, the intervening toner is scraped off at that point, so that the adhesion of the toner between the rollers is prevented.

Therefore, in the developing device characterized by the constitution according to the first aspect of the present invention, if the control section is arranged to stop the rotation of the developing roller after the completion of the developing operation, the portion which is naturally stopped. It is possible that the toner is scraped off, and the toner is fixed at the contact portion without being interposed between the toner and the regulation roller.

Further, in the developing device characterized by the constitution according to the above-mentioned first invention, in the control section, the potential of the developing roller is set to 0, and the voltage value supplied to the regulating roller is equal to or lower than the discharge start voltage. With the configuration in which the switching control is performed so as to supply the voltage of the polarity opposite to the charging polarity of the component toner, the toner is efficiently attracted from the developing roller side to the regulation roller side, and the toner is scraped off by the rotation of the regulation roller. Increase. Moreover, since the discharge start voltage is set to be equal to or lower than the discharge start voltage, the influence of the discharge can be eliminated. That is, it is possible to prevent the toner from being melted and fixed due to the heat generated by the discharge, and at the same time preventing the toner from being charged by the discharge.
Stable charge can be maintained.

Further, in the developing device according to the first aspect of the invention having the above-mentioned structure, the control section causes the restriction roller to continuously rotate after completion of the development operation at least one rotation of the restriction roller. By setting the time and controlling so that the rotation of the regulation roller is stopped after the lapse of the time, the effect of writing the toner on the developing roller side is enhanced, so that the problem of toner sticking can be reliably eliminated.

Further, the first feature of the above-mentioned configuration
In the developing device according to the invention, the regulating roller is rotated in the opposite direction at the contact portion with the developing roller, and is configured to be continuously rotated in that direction after the completion of the developing operation by the control unit. Once you have naturally increased scraping overlooked Shi effect of the toner, the toner is not to be fixed at a pressure in the developing roller and the press contact portion after stop of the rotation of the regulating roller.

[0028]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. An embodiment of the developing device of the present invention will be described with reference to FIGS. FIG. 1 is a diagram including a control circuit portion relating to voltage supply control and drive control to a developing device according to the present invention, and FIG. 2 is a control procedure by the developing device of the present invention shown in FIG. 1, that is, after completion of development. Showing the control flow chart of
FIG. 3 is a timing chart thereof, and FIG. 4 is a configuration diagram for explaining the outline of the structure of the developing device according to the present invention. Further, FIG. 5 is a schematic configuration diagram showing an example of an image forming apparatus provided with the developing device of the present invention.

First, the schematic structure of the image forming apparatus will be described with reference to FIG. Reference numeral 1 is a photoconductor that is disposed substantially in the center of the main body of the image forming apparatus and constitutes an image bearing member that carries an electrostatic latent image formed in a drum shape that is rotationally driven in the arrow direction at a constant speed during an image forming operation. Is. Various image forming process means are arranged so as to face the periphery of the photoconductor 1.

The means (apparatus) constituting the above-mentioned image forming process includes a charger 2 for uniformly charging the surface of the photosensitive member 1, an optical system for irradiating an image 3 of light according to an image (not shown), and exposure by the optical system. The developing device 4 according to the present invention for visualizing the electrostatic latent image formed on the surface of the photoconductor 1 by the above, and the sheet-like sheet to which the developed image (image of the toner 10) is appropriately conveyed. Transfer device 5 for transferring to the sheet of paper P, residual developer (toner) not transferred to the surface of the photoconductor 1 after transfer
A cleaning device 6 that removes the charge, a charge eliminator 7 that removes the electric charge remaining on the surface of the photoconductor 1, and the like are arranged in this order in the rotational direction of the photoconductor 1.

The sheet P is accommodated in a large amount in, for example, a tray or a cassette, and one sheet of the accommodated sheet is fed by the feeding means and faces the photoconductor 1 on which the above-mentioned transfer device 5 is arranged. The toner image formed on the surface of the photoconductor 1 is fed to the transfer area so as to coincide with the front end of the toner image. The sheet P after the transfer is peeled off from the photoconductor 1, and the fixing device 8
Sent to.

The fixing device 8 fixes the unfixed toner image transferred onto the sheet as a permanent image.
A surface facing the toner image is composed of a heat roller heated to a temperature for melting and fixing the toner, and a pressure roller or the like for pressing the heat roller to bring the paper P into close contact with the heat roller is provided. Are configured. The paper P that has passed through the fixing device 8 is discharged to the outside of the image forming apparatus via a discharge roller and onto a discharge tray (not shown).

If the image forming apparatus is a copying machine, the optical system (not shown) irradiates the copy original with light and irradiates the reflected light from the original as an optical image 3. Alternatively, if the image forming apparatus is a printer or a digital copying machine, the optical system irradiates an optical image in which a semiconductor laser is driven ON-OFF according to image data. Particularly in a digital copying machine, image data obtained by reading reflected light from a copy original with an image reading sensor (CCD element or the like) 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. Further, in the printer, an optical image is converted according to image data from another processing device such as a word processor or a personal computer, and the image is irradiated. Not only the semiconductor laser but also an LED element, a liquid crystal shutter, etc. are used for the conversion into the optical image.

As described above, when the image forming operation in the image forming apparatus is started, the photoconductor 1 is rotationally driven in the direction of the arrow, and the surface of the photoconductor 1 is uniformly charged by the charger 2 to the potential of the specific polarity. It After this charging, the optical image 3 is irradiated by the above-described optical system, and an electrostatic latent image corresponding to the optical image is formed on the surface of the photoconductor 1. In order to visualize this electrostatic latent image, it is developed by the next developing device 4. In the present invention, this development is development with a one-component toner, and the toner is selectively attracted to the electrostatic latent image formed on the surface of the photoconductor 1 by, for example, electrostatic force, and the development is performed.

The toner image on the surface of the photosensitive member 1 thus developed is electrostatically transferred onto the sheet P, which is conveyed in synchronization with the rotation of the photosensitive member 1, by the transfer device 5 arranged in the transfer area. Transcribed. In this transfer, the transfer device 5 charges the back surface of the sheet P with a polarity opposite to the charging polarity of the toner, so that the toner image is transferred to the sheet P side.

After the transfer, a part of the toner image that has not been transferred remains on the surface of the photoconductor 1, and this residual toner is removed from the surface of the photoconductor 1 by the cleaning device 6, and
In order to reuse the above, the surface of the photoconductor 1 is neutralized by the static eliminator 7 to a uniform potential, for example, approximately 0 potential.

On the other hand, the sheet P after transfer is peeled off from the photoconductor 1 and conveyed to the fixing device 8. This fixing device 8
At this point, the toner image on the sheet P is melted and pressure-bonded to the sheet P by the pressure applied between the rollers to be fused. This fixing device 8
The sheet passing through the sheet is discharged as a sheet P having the image formed thereon to a discharge tray or the like provided outside the image forming apparatus.

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

The structure of the developing device for developing with one-component toner will be described with reference to FIG.
Includes a developing roller 41 rotatably in a developing tank 40 containing a one-component toner, for example, a non-magnetic one-component toner 10, and a supply roller 42 for supplying the one-component toner 10 to the developing roller 41 side. A screw roller 9 for feeding the one-component toner 10 to be replenished as needed into the developing tank 40 is provided on the right side of the figure of 40.

The developing roller 41 provided in the developing tank 40 has a developing area facing the photoconductor 1 in the figure in order to convey toner to the developing area which is partially exposed and faces the photoconductor 1 described above. Are provided so as to rotate in the same direction. The supply roller 42 described above is pressed against the developing roller 41 at a position opposite to the developing area.

As the structure of the developing roller 41, for example, the surface of a metal roller (including the rotating shaft) is coated with a porous elastic body such as sponge. As the elastic material such as sponge, if carbon such as polymer foam polyurethane is dispersed, or if ion conductive solid rubber or the like is used, it is possible to maintain a predetermined resistance value such as toner fusion. As described later, it works effectively when the developing bias voltage is supplied.

A drive motor (not shown) is connected to the developing roller 41, and the developing roller 41 is rotationally driven in the direction of the arrow in the figure. One-component non-magnetic toner 1
0 is attracted to the surface of the developing roller 41 that rotates, and is conveyed to the developing area facing the surface of the photoconductor 1. Further, since the developing roller 41 is pressed against the surface of the photoconductor 1, the pressed area becomes the developing area, and the one-component toner 1
0 is attracted to the electrostatic latent image on the surface of the photoconductor 1 and developed.

The above-mentioned one-component toner 10 is, for example, a one-component non-magnetic toner having an average particle diameter of about 10 μm, and polyester type toner or styrene acrylic type toner is used.

A developing bias voltage Va is supplied from the developing bias power supply circuit 11 to the developing roller 41. The developing bias voltage Va is set to such a polarity and voltage value that toner is attached to the electrostatic latent image formed on the photoconductor 1 and toner is not attached to other areas, that is, non-image areas.

The supply roller 42, in the rotation direction, is located at a portion (press contact area) facing the developing roller 21.
It is driven to rotate in the opposite direction to the rotation direction of.
The supply roller 42 uses the same material as the developing roller 41, and the electrical resistance can be adjusted with the same resistance adjusting material as the developing roller 41. Further, in order to further increase the elasticity of the supply roller 42, a foamed material is used, and the amount of the foaming agent used is larger than that of the developing roller.

A bias voltage Vc is applied from the bias power supply circuit 12 to the supply roller 42, and generally, the toner is pushed (moved) to the developing roller 41 side, that is, the toner on the supply roller 42 side. Bias voltage is set in the direction of repelling the toner and supplying it to the developing roller 41. For example, when the toner of negative polarity is used, a larger bias voltage Vc is supplied to the supply roller 42 on the negative side.
Is being applied to.

A drive motor (not shown) is connected to the developing roller 41 and the supply roller 42, and by being driven to rotate in the direction of the arrow in the figure, the supply roller 42 supplies toner to the developing roller 41 and after development. The residual toner on the surface of the developing roller 41 that has not contributed to the development is peeled off (removed). The toner 10 supplied by the supply roller 42 is adhered to the surface of the developing roller 41, and the amount of toner adhered to the surface of the developing roller 41 is appropriately pressed before being conveyed to the developing area facing the surface of the photoconductor 1. The amount of toner adhesion is regulated by the regulation roller 43, which is a member for regulating the toner, to regulate the toner layer thickness to a constant value.

The regulation roller 43 is pressed against the developing roller 41 with an appropriate pressure. This regulation roller 43
The developing roller 41 is rotationally driven in the same direction as the developing roller 41 so as to rotate in mutually opposite directions at a position where the developing roller 41 comes into contact. The regulation roller 43 has a hard roller configuration made of a metal material, a hard resin material, or the like, and a predetermined amount is supplied from the bias power supply circuit 13 in order to set the toner 10 precharged by the supply roller 42 to a desired charge amount. Is supplied with the voltage Vb. Even with this bias voltage Vb, toner 1
0 pushing direction to the developing roller 41 side, a large value to a negative polarity side more if negative toner For example are set.
The bias voltage Vb supplied to the regulation roller 43 is
The developing bias voltage Vb supplied to the developing roller 21 and the absolute value are set to a larger value.

On the other hand, the toner 10 conveyed to the developing area facing the photoconductor 1 is selectively adhered according to the electrostatic latent image formed on the surface of the photoconductor 1, and the electrostatic latent image is colored with the toner. To visualize. Then, the toner 10 that has not contributed to the development is returned into the developing tank 40 by the rotation of the developing roller 41. At the returning position, a toner seal member 44 is provided so as to be in pressure contact with the developing roller 41. The seal member 44 is arranged in front of the supply roller 42 in the rotation direction of the developing roller 41, and one end thereof is fixed to the developing tank 40 so as to be appropriately brought into pressure contact with the developing roller 41. The developing roller 41 is pressed against the developing roller 41 by utilizing its spring property.

As described above, the developing device 4 uses the toner 1
0 is conveyed to a region facing the photoconductor 1, and the latent image on the surface of the photoconductor 1 is visualized. The toner image on the surface of the photoconductor 1 is transferred to the sheet P, which is appropriately conveyed in the transfer area as described above, by the action of the transfer device 5, and the sheet passes through the fixing device 8 to the outside of the image forming apparatus. Is discharged.

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

The features of the present invention, that is, the embodiment of the developing device 4 of the present invention will be described in detail below with reference to FIGS.

(Embodiment of the Invention) The developing roller 41 is
As described above, the structure will be described in more detail. The developing roller 41 has, for example, a rotating shaft made of stainless steel having a diameter of 18 mm and a conductive agent such as carbon black added thereto, and has a low volume efficiency of about 10 ⁶ Ωcm, JIS-A.
Conductive urethane rubber with a hardness of 60-70 degrees has a diameter of 34 mm
And the surface roughness Rz = 3 to 6 μm.
(According to JIS B-0601). The developing roller 41 has a contact depth of 0.
It is pressed against the toner layer with a thickness of 1 mm to 0.3 mm, and is rotationally driven in the direction of the arrow through a drive motor (not shown).
The peripheral speed of the developing roller 41 is 285 mm / sec.
Driven by. These are merely examples and the present invention is not limited thereto.

The developing bias voltage Va of the developing bias power supply 11 supplied to the rotating shaft of the developing roller 41 is the photosensitive member 1 when the charging characteristic of the one-component toner is, for example, negative.
To the relationship between the charge potential, but is set to, for example, -350 V.

Next, the supply roller 42 also has a function of agitating the toner in the developing tank 40 and removing the residual toner after the development by the developing roller 41 from the developing roller 41. The supply roller 42 has a rotation shaft covered with a conductive porous foam member.

The above porous foam has a low volume efficiency of about 10 ⁵ Ωcm and a porous cell density of 80 to 140.
It is made of a conductive urethane foam with a unit / inch and an Asuka F hardness of 60 to an Asuka C hardness of 30 degrees. In this polyurethane foam, 5 parts by weight or more and 15 parts by weight or less, and in some cases about 70 parts by weight of carbon black is mixed with 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 having the above-mentioned cell density, for example, polyurethane foam and carbon black are mixed, stirred with a whisk, and after foaming, they are heated and blown to form a stainless steel rotating shaft having a diameter of 8 mm. The supply roller 42 is formed by covering the periphery so as to have a diameter of 20 mm.

The supply roller 42 is pressed against the developing roller 41 so as to have a contact depth of about 0.5 mm to 1 mm, and has a peripheral speed of 17 through a drive motor (not shown) in the direction of the arrow.
It is driven to rotate at 0 mm / sec. The supply roller 42 is supplied with the voltage Vc (for example, -500V) from the toner supply bias power source 12 on the rotation shaft.

Further, the regulating roller 43 is rotated as shown in FIG. 4 and is pressed against the developing roller 41 with an appropriate pressure. As a result, the toner is triboelectrically charged, and an electric charge suitable for development is applied to the toner, and at the same time, the amount of adhesion to the developing roller 41 is regulated to be constant.

The regulation roller 43 is made of, for example, a metal material or a hard resin material. In addition, the regulation roller 43
Is driven to rotate in the same direction as the developing roller 41, that is, in the counterclockwise direction in FIG. 4, and the amount of toner on the developing roller 41 supplied by the supply roller 42 is set to, for example, about 10 to 15 μm as a toner layer thickness. regulate. Similarly, on the roller shaft of the regulation roller 43, the regulation bias voltage V for regulating the toner layer from the toner layer thickness regulation bias power source 13 is applied.
b (-450V) is supplied.

The toner which is a non-magnetic one-component developer used in the present invention will be described below. This one-component toner is a styrene-acrylic copolymer 80 to 90 parts by weight, carbon black 5 to 10 parts by weight, and a charge control agent 0 to 5 parts by weight. By classification, a negatively charged toner having an average particle size of about 5 to 10 μm can be obtained. To this toner, silica (Si) added internally or externally in order to improve fluidity is obtained.
O ₂₎ to be added 0.5 to 1.5 parts by weight, it is possible to obtain a one-component toner of non-magnetic.

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

The non-magnetic one-component toner is not limited to the above-mentioned composition materials, and the following compositions can be used in the developing device of the present invention.

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

Further, as the colorant, in the case of a black toner, in addition to the above-mentioned carbon black, there are furnace black, nigrosine type dye, metal-containing dye and the like. And for color toner, benzidine yellow pigment for yellow, phonon yellow, acetoacetic acid anilide insoluble azo pigment, monoazo pigment, azomethine dye, etc., xanthene magenta dye for magenta, phosphotungsten molybdate lake pigment, anthraquinone Dyes, coloring materials composed of xanthene dyes and organic carboxylic acids, thioindigo, naphthol insoluble azo pigments, and copper phthalocyanine pigments for cyan.

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

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

In the developing device 4 using the one-component toner as described above, the adhering amount of the toner 10 is regulated by the regulating roller 43 pressed against the developing roller 41 so that the toner 10 has a constant layer thickness. After that, the toner 10 is conveyed to the developing area to develop the electrostatic latent image on the surface of the photoconductor 1. At this time, the bias voltages Va, Vb, and Vc are supplied to the developing roller 41, the supply roller 42, and the blade 43, respectively, and good development is performed by these.

The photoconductor 1 has a photosensitive layer made of an organic material having a negative charging property formed on the surface of a drum-shaped conductive substrate, and has a diameter of, for example, 65 mm and a peripheral speed of 190 mm / sec in the direction of the arrow in FIG. It is driven to rotate.
The photosensitive member 1 is uniformly charged to about the surface potential, for example, about -550V with a charging device 2 in FIG.

(Example of Control of Developing Device According to the Present Invention) In the developing device 4 according to the present invention, the developing roller 4 in FIG.
1. The rotation drive of the supply roller 42, the supply roller 42, and the regulation roller 43 and the supply control of the bias voltage are controlled by the control unit 50 that controls the entire drive of the image forming apparatus main body described with reference to FIG. In the developing device shown in FIG. 4, the control unit 50 causes the power supply circuits 11 to 13 to supply the bias voltages to the rollers via the control circuit 51. Further, in order to control the drive of the developing roller 41, the supply roller 42, and the regulation roller 43, the rotation is performed via the rotation drive control circuit 52 of those drive units, and the image including the control of various process means shown in FIG. It is configured to execute a control for forming.

In the present invention, when the developing device 4 is driven,
At the time of development, as in the conventional case, as described above, by supplying a predetermined bias voltage through the power supply circuits 11, 12 and 13, the electrostatic latent image formed on the photoconductor 1 is formed by toner. Visualize. Therefore, in response to the image formation command, the control unit 50 forms an electrostatic latent image on the photoconductor 1 by rotating the photoconductor 1 and driving the charger to expose the light image.

The electrostatic latent image is then developed by the developing device 4. Therefore, the control unit 50 rotates the developing roller 41 via the drive control circuit 52. At the same time, the supply roller 42 and the regulation regular roller 43 are rotationally driven in the arrow direction in FIG. As a result, the developing roller 41 is regulated to a certain amount of toner layer thickness, and the regulated toner is conveyed to the developing area. The control unit 50 controls the supply roller 42 and the regulation roller 43 in order to obtain a certain amount of toner layer.
Is rotated in the direction shown in the drawing, and the voltage control circuit 51 is controlled so as to supply the determined bias voltage from each of the power supply circuits 11 to 13.

In this way, when the image forming operations are sequentially executed and the developing operation is completed, the control section 50
The stop of the developing process by the developing device 4 is controlled. In this case, in the present invention, the control according to the control flowchart of FIG. 2 and the timing chart of FIG. 3 is executed.

Before describing the control after development according to the present invention, a conventional control case will be described with reference to FIG. FIG. 3
As shown in (b), the developing operation is executed by the image forming operation as described above, and when the developing operation is completed,
The rotation of the developing roller (developer carrier) 41 is stopped, and the rotation of the regulation roller 42 is also stopped accordingly (O
FF) Then, in synchronism with the rotation stop of the developing roller 41 and the regulating roller 43, the supply of the developing bias voltage Va and the bias voltage Vb of the regulating roller is cut off (OF
F) Yes.

Therefore, the toner remains on the developing roller 41 between the regulating roller 43 and the developing roller 41, and the developing roller 41 stands by in a pressed contact state. Therefore, the toner may stick to that portion. If the next developing operation is started due to the adhesion of the toner, the toner layer cannot be made uniform by the regulation roller 43, which may cause defective development.

On the other hand, according to the present invention, the developing device 4
When the developing operation is executed and the developing is completed, the post-processing for stopping the operation of the developing device in response to the developing operation is the control unit 5.
Executed through 0. The processing procedure is as shown in FIG. 2, and the timing chart thereof is shown in FIG.

That is, in response to the completion of the developing operation by the developing device 4, the control section 50 executes the control shown in FIG.
In FIG. 2, first, a developing roller 41 which is a developer carrying member.
Drive is stopped via the drive control circuit 52. At the same time, the control unit 50 stops the supply of the developing bias voltage Va, that is, turns it off (S11). That is, FIG.
As shown in (a), the control unit 50 is synchronized with the timing (time point) in response to the completion of the developing operation by the developing device 4.
Stops the rotation of the developing roller 41 and stops the supply of the developing bias voltage Va to the developing roller 41, that is, sets it to 0 potential (turns off). At this time, the supply roller 42 is also stopped from rotating, and the supply of the bias voltage Vc is also stopped (OFF).

At the same time, the rotation of the regulation roller 43 is continued via the drive control circuit 52, and the bias voltage Vb supplied to the regulation roller 43 is controlled by the voltage control circuit 51.
Switching control is performed in the positive direction via (S12). For example, as shown in FIG. 3A, the control circuit 51 supplies the bias voltage Vb of −450 V to the negatively charged toner during the developing operation, but the control circuit 51 responds to the completion of the developing operation and outputs the voltage of +100 V. Controls switching to bias voltage.

After that, the bias voltage switched after the completion of development supplied to the regulation roller 43 is set to a time t which will be described later in detail (S13), and the set time t is set.
It is confirmed whether or not has passed (S14). If this set time t is confirmed (passed), the rotation of the regulation roller 43 is stopped, and at the same time, the supply of the switched bias voltage Vb is stopped (OFF) (S15), and the post-processing after the development is completed. finish.

By executing the control by the developing device 4 as described above, it is possible to prevent the residual toner which is interposed in the pressure contact portion between the regulation roller 43 and the developing roller 41, including during standby, from being fixed. You can do it. The action of the present invention that can prevent this will be described below.

[0081] In the developing apparatus 4, during the developing process, i.e. during operation, at least the developing roller 41, the regulating roller 43 and are rotated in the direction of, respectively it, bias voltage that is determined is supplied . For example, in the example described above, −350V is supplied to the developing roller 41 and −450V is supplied to the regulation roller 43.

In relation to the bias voltage during the developing operation, the negatively charged toner is pushed toward the developing roller 1 side.
FIG. 6A shows this state in the arrow direction. The toner removed by the regulation roller 43 is not attracted to the regulation roller 43 side because of the above-mentioned relationship,
Then, unnecessary toner on the developing roller 41 is scraped off, and the toner layer is regulated to an appropriate thickness. And
Since the regulation roller 43 is not always pressed against the developing roller 41 at the same portion, toner adhesion is suppressed.

When the developing operation is completed, as described above, the developing bias voltage Va of the developing roller 41 becomes O.
The bias voltage Vb that is FF (0 potential) and is supplied to the regulation roller 43 is switched and controlled to + 100V. Further, the rotation of the regulation roller 43 is maintained. In this case, as shown in FIG. 6B, the bias voltage Vb for regulating the layer thickness is the developing bias voltage Va of the developing roller 41.
As a result, the voltage becomes higher by 100 V, and there is a potential difference relationship in which the toner is attracted toward the regulation roller 43 side as shown by the arrow. That is, the toner adhering to the developing roller 41 is attracted to the regulating roller 43 side while the regulating roller 4
3 will be rotated.

The toner attracted to the regulation roller 43 in this way drops like being scraped into the developing tank 40 without being fixed to the regulation roller 43. At this time, the potential difference between the regulation roller 43 and the developing roller 41 is 10
It is as low as 0V, and there is no discharge between them.

That is, although the potential difference depends on the impedance and the like, it is conceivable to start the discharge when the potential difference exceeds 400V. Due to this discharge, the heat melts the toner and there is a risk that it will stick, but
According to the above-described example of the present invention, there is no fear of starting the discharge, and the toner adhering to the developing roller 41 side can be scraped off by the regulation roller 43. Therefore, the toner pressed against the developing roller 41 and the regulation roller 43 is efficiently scraped off, and the fixed toner is not present. Therefore, the cause such as the toner sticking can be eliminated, and the toner is fixed by the heat generated by the discharge. It will not be done.

Further, the time during which the regulation roller 43 is continuously rotated in accordance with the completion of the developing operation, that is, the predetermined time t, may be set to at least the time during which the regulation roller 43 makes one rotation. Therefore, from the time when the switching control of the bias voltage Vb to the regulation roller 43 is performed, the regulation roller 4
The time t for 3 to make one rotation or more is set. Particularly, as the time t for continuously rotating the regulation roller 43, the regulation roller 4 is
By setting the time for 3 to about 5 to 6 rotations, the preferable result that the defect of the fixing of the toner can be eliminated was obtained.

As described above, the developing device 4 of the present invention
In (1), after the development is completed, only the rotation of the regulating roller 43 is continued and the rotation of the developing roller 41 is stopped. Then, the potential difference that allows the toner adhering to the developing roller 41 to easily move to the regulating roller 43 side is set. As a result, the toner attached to the developing roller 41 between the developing roller 41 and the regulation roller 43 can be scraped off, and the toner can be prevented from sticking to the developing roller.

Further, according to the above-mentioned case, since the potential difference between the developing roller 41 and the regulating roller 43 after the completion of the development is set to 100 V, the electric discharge does not occur after the development as described above. Without being limited to this example, the bias voltage Vb supplied to the regulating roller 43 with respect to the developing roller 41 may be set to a value such that the toner attached to the developing roller 41 is attracted to the regulating roller 43 side. good. In this case, the setting voltage difference below the discharge start voltage child between the developing roller 41 and the regulating roller 43 are preferred.

Particularly, when the discharge is generated, there is a fear that the toner or the like adhering to the developing roller 41 may be fixed due to the heat generated by the discharge, and the toner may be reversely charged or excessively charged by the discharge to be charged. It can prevent the quantity from becoming unstable.

According to the embodiment of the present invention, the negatively charged toner has been described as an example of the toner. However, when the positively charged toner is used, the bias voltage supplied to the developing roller 41, the regulating roller 43 and the like is of the positive polarity. You can do this. Then, as shown in FIG. 6, the potential difference is set so that the toner easily moves to the developing roller 41 side during development, and after the development is completed, the potential difference is set so that the toner is attracted to the regulation roller 43 side. It is sufficient to set the potential difference to the discharge start voltage or less.

Further, in the timing chart of FIG. 3A, the controller 50 of the developing device 4 according to the present invention
When the predetermined time t after the development is completed, the regulation roller 43
The control bias voltage Vb is controlled to the 0 potential, that is, the OFF state at the same time that the rotation of is stopped. If the regulation bias voltage is continuously supplied in a state where the rotation of the regulation roller 43 is stopped, Joule heat due to the flowing current is generated even if this voltage is equal to or lower than the discharge start voltage, and the toner between the rollers 41 and 43 is generated. There is a fear that the sticking of the sword will come.
Therefore, when the rotation is stopped, the supply of the restriction bias voltage Vb supplied to the restriction roller 43 is stopped to eliminate the above-mentioned inconvenience.

According to the above-described embodiment of the present invention, the case where the developing roller 41 is provided so as to contact the photosensitive member 1 has been described. However, the present invention is not limited to such an apparatus, and can be similarly applied to a developing apparatus of a system in which the developing roller 41 is arranged at a predetermined interval with respect to the photoconductor 1, and can be applied as it is. Of course.

[0093]

According to the developing device using the one-component toner of the present invention, the toner adhesion amount is regulated with respect to the developing roller that carries the toner and conveys the latent image to the developing position of the image carrier. By forming the regulation member in the shape of a roller, it is possible to regulate the amount of adhered toner constantly.

In this case, the bias voltage is switched and controlled so that the toner interposed between the developing roller and the regulation roller is fixed during the standby after the development, and a potential difference is generated so that the toner is attracted to the regulation roller side after the development. By performing the operation and continuing the rotation of the regulation roller, it is possible to effectively prevent the toner from sticking.

Further, by setting the potential difference between the rollers to be equal to or lower than the discharge start voltage, it is possible to prevent the toner sticking due to the discharge and the unstable charge amount of the toner.

[Brief description of drawings]

FIG. 1 is a diagram showing a control circuit configuration showing an example of a control example for explaining an embodiment of a developing device for a one-component toner of the present invention.

FIG. 2 is a control flowchart showing a control procedure in the control circuit configuration shown in FIG. 1, particularly a control procedure of a developing device after completion of development.

3A and 3B are timing charts showing control timings according to the control flowchart of FIG. 2, where FIG. 3A is a timing chart in the present invention, and FIG. 3B is a conventional timing chart.

FIG. 4 is a configuration diagram for explaining the internal structure of a one-component toner developing device of the present invention.

FIG. 5 is a configuration diagram showing a schematic configuration of an image forming apparatus including a developing device of the present invention.

FIG. 6 is a diagram for explaining the operation according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a configuration of a conventional developing device.

[Explanation of symbols]

1 Photoconductor (electrostatic latent image carrier) 4 Developing device 10 (non-magnetic) one-component toner 11 Power supply circuit for developing bias voltage supply 12 Power supply circuit for voltage supply to regulation roller 13 Power supply circuit for voltage supply to supply roller 40 developing tank 41 developing roller 42 Supply roller 43 Regulation Roller 50 control unit 51 Bias voltage control circuit 52 Rotation drive control circuit

Continuation of the front page (56) Reference JP-A-2-116872 (JP, A) JP-A-5-11598 (JP, A) JP-A-10-123831 (JP, A) JP-A-4-24668 (JP , A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/08 504 G03G 15/06 101

Claims (3)

(57) [Claims] 1. A developing roller that carries a one-component toner and conveys the toner to a developing area facing the electrostatic latent image carrier, and the developing roller is in a stage before the developing roller conveys the toner to the developing area. In a developing device having a regulating roller in which a regulating member for regulating the amount of toner adhered to the roller is formed into a roller shape, in response to completion of the developing operation of the developing device ,
The developing roller that has been rotationally driven is stopped, the regulating roller is continuously rotated , and the potential difference between the developing roller and the regulating roller is opposite to the potential difference during the developing operation and the toner is regulated to the regulating roller side. with the regulating roller a voltage value supplied to the switching control to become the control unit so as to be such a value draw to, and the control unit, the potential of the developing roller is set to 0 and the regulations
When the voltage value supplied to the control roller is below the discharge start voltage, development
A one-component toner developing device, which is controlled to switch to a voltage having a polarity opposite to that during operation . 2. The control unit sets the time for continuously rotating the regulation roller after the completion of the developing operation to a time at which the regulation roller makes at least one rotation, and after the time elapses ,
The control means is for stopping the rotation of the regulating roller and supplying the supply voltage.
2. The one-component toner developing device according to claim 1 , wherein the stop is performed . Wherein the regulating roller, the contact portion between the developing roller are rotated so that the opposite direction, it has to be continued rotation after completion development operation in that direction by the control unit The one-component toner developing device according to claim 1.