JP2000305351A - Developing device for one component toner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make the size of a developing device small by efficiently removing toner that is remaining after developing on a developing roll where one component toner is carried and developing is carried out. SOLUTION: In this device, a feeding roll 42 is provided in pressurized contact with a developing roll 41 where the one component toner is carried and transported so that it comes into contact with the photoreceptor where an electrostatic latent image is carried. In addition, a removing rod 44 is provided to come into pressurized contact with the developing roll 41 from behind through an elastic plate 45 to eliminate the toner immediately after a developing range 46 where the developing roll 41 is faced to the photoreceptor 1 and the toner that is in a state where it is easily isolated from the developing roll 41 directly after developing is efficiently eliminated by the removing rod 44 with a small diameter. Furthermore, the device is made small by having the removing rod 44 installed close to the developing range 46 side.

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,
The need for toner concentration control is eliminated, the mechanism for stirring the developer can be simplified, and the developing roller can be reduced in size and weight.

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. 5, 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 disposed so as to be partially exposed at the opening of the developing tank and to be in contact with or separated from the photoconductor 1, for example. Therefore, a part of the region where the two oppose each other is a development region. The developing roller 5
1 may be arranged at a predetermined distance from the photoconductor 1.

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 51, 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 failure occurs due to aging and the life of the developing roller 51 is reduced. Be faster. Therefore, the collected toner needs to be surely removed from the developing roller 51.

For this purpose, Japanese Patent Application Laid-Open No. 4-2955871 discloses a plate-like scraping member 55 as shown in FIG. 5, wherein the tip of the scraping member 55 is provided so as to press 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. 6 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, a seal roller 56 made of a rotating elastic member (rubber) for removing toner is provided in place 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, according to the structure shown in FIG. 5 in which the scraping member 55 as the toner removing means after the development is provided, the toner can be removed satisfactorily. The toner (recovered toner) removed from the roller 51 cannot be efficiently reused. That is, only the scraping is performed.
2, the toner may not be satisfactorily circulated due to reuse of toner, and may accumulate in the lower developing tank.

Further, the toner removed by the scraping member 55 may be scattered without being collected in the developing tank 50. Therefore, the lower end of the developing tank 50 is
It is necessary to provide it so as to be close to the side or the surface of the photoconductor 1. However, in the case where the developer tank 50 is brought into close proximity, if the developing tank 50 comes into contact with the toner, it will scatter or disturb the developed image, so a gap will inevitably occur, and the toner removed by the scraping member 55 will scatter. Can not be prevented. Further, the tip of the scraping member 55 is
, The surface of the developing roller 51 may be damaged when the toner is scraped off.

In this respect, according to the structure shown in FIG. 6, the toner after development is removed by the rotating seal roller 56. Therefore, damage to the developing roller 51 can be prevented. In addition, the seal roller 5 after the removal
By providing the seal sheet 57 so as to be in pressure contact with the developing roller 6, it is possible to increase the sealing effect without scattering the toner removed from the developing roller 51.
Therefore, the problem of toner scattering can be solved.

However, since the one shown in FIG. 6 pays particular attention only to the point of removing the toner from the developing roller 51, the diameter of the seal roller 56 becomes substantially equal to the diameter of the supply roller 52. The whole device becomes large. Also,
After development, the seal roller 56
Near the developing roller 51. In this case, since the attracting force between the developing roller 51 and the toner acts strongly, the removal effect is reduced. Therefore, in order to increase the efficiency, it is necessary to make the roller diameter of the seal roller 56 as large as possible. As a result, the entire developing device becomes large.

The present invention has been made in view of the above problems, and in a developing apparatus using a one-component toner, it is intended to provide a developing device capable of reliably removing toner remaining on a developer roller after development and capable of being downsized. Aim.

Another object of the present invention is to provide a developing device capable of enhancing a sealing effect so that toner after removal is not scattered.

[0022]

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; A developing roller provided with a developing roller for transporting the developing roller to the developing roller, the rotatable removing rod being pressed against the developing roller immediately after the developing roller to remove the developed toner from the developing roller. Is provided.

By arranging the removal rod immediately after the development area, the efficiency of removing the toner adhered to the development roller after development can be improved. In other words, in the developing area, the toner tends to move toward the carrier between the latent image carrier and the toner. That is, for development, the toner is sucked toward the latent image carrier,
The toner has a very strong tendency to separate from the developing roller, and can be easily removed. Therefore, even if the removing rod is not strongly pressed against the developing roller immediately after the developing area, the removing rod can be removed satisfactorily and the removing efficiency can be increased. Further, since the removal becomes easy without increasing the diameter of the removal rod, the entire developing device can be downsized.

According to the second aspect of the present invention, there is provided a one-component toner developing apparatus having the above-described structure.
The removal rod has a circular section and a small diameter to be provided immediately after the downstream side of the development area, and the back surface is provided so as to be pressed against the development roller by an elastic plate. And According to such a configuration, if the entire developing device can be reduced in size, and the rear surface of the removing rod is pressed through the elastic plate and pressed against the developing roller, the elastic plate is integrated with the developing tank. When it is formed, the adhesion in the developing tank can be improved, and the sealing effect of the collected toner can be enhanced.

According to the third aspect of the present invention, in the one-component toner developing apparatus having the above-described structure, the removing rod is formed of a conductive member and has the same polarity as the toner. In addition, a voltage lower in absolute value than the developing bias voltage supplied to the developing roller is supplied. By supplying such a bias voltage, the effect of removing the toner from the developing roller is promoted, and at the same time, the toner is not attached to the toner removing rod side.
The toner can be collected and efficiently reused.

According to a fourth aspect of the present invention, in the apparatus for developing a one-component toner, the removing rod is provided in a direction opposite to a rotation direction of the developing roller. Is driven to rotate at a peripheral speed higher than the peripheral speed at which it is rotated. Since the rotation speed of the removing rod is high, the effect of removing the toner attached to the developing roller side is further enhanced.

On the other hand, in the one-component toner developing device having the above-mentioned configuration, according to the invention of claim 5, a position downstream of the removing rod in the rotation direction of the removing rod with respect to the pressure contact position between the removing rod and the developing roller. The tip of a scraping member for scraping off the toner adhered to the removing rod by pressing against the removing rod is abutted, and the scraping member is fixed to the elastic plate. With this configuration, the removed toner is collected in the developing tank, and does not scatter outside. Moreover, since the surface of the removing rod can be reliably cleaned by the scraping member, the effect of removing the toner by contacting the developing roller again can be enhanced. In this case, the removal rod can be made of a hard material, and is not damaged by the scraping member.

According to a sixth aspect of the present invention, in the one-component toner developing apparatus having the above-described structure, an elastic member is interposed between the removing rod and the elastic plate. . In this way, the removing rod can be pressed against the developing roller by the elastic member, so that a more stable pressed state can be maintained, and the fear of damaging the developing roller surface can be eliminated, and the removal efficiency can be promoted. Also, if the elastic member is made of a foamed member,
Naturally, the cleaning effect is enhanced, and the toner can be removed from the developing roller in a clean state.

In the above-described configuration, the effect of removing the toner adhering to the developing roller after the development is enhanced, and the development failure due to the fusion of the toner to the developing roller is eliminated, and the development can be stabilized for a long period of time.

[0030]

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. 2 is a view showing toner after development adhering to a developing roller in FIG. 3 is an enlarged view of a main part showing another embodiment for enhancing the removing effect, and FIG. 3 is an enlarged view of a main part showing still another embodiment.

FIG. 4 is a structural diagram for schematically explaining the structure of an image forming apparatus provided with the developing device of the present invention shown in FIG.

First, the 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.

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.

Means (apparatus) constituting the image forming process include a charger 2 for uniformly charging the surface of the photoreceptor 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 a charged charge remaining on the surface of the photoconductor 1 are provided. In this order, photoconductor 1
Are arranged in the rotation direction.

A large number of sheets P are accommodated in, for example, a tray or a cassette, and the accommodated sheets are fed one by one by feeding means, and are opposed to the photoreceptor 1 on which the above-described transfer device 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 of 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. 4 corresponds to the development 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 to transport 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 46 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 36.

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.

A drive motor (not shown) is connected to the developing roller 41, 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 internally or externally added 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, etc., in addition to the styrene-acrylic copolymer.

As a coloring agent, in the case of a black toner, in addition to using the above-described carbon black, there are furnace black, nigrosine dyes, metal-containing dyes, and the like. 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.

A 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 41 (pressure contact area).
The direction shown in FIG. 4 (S
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 directions indicated by arrows S3 and S2 in FIG.
2 supplies toner to the developing roller 41,
The residual toner on the surface of the developing roller 41 that has not contributed to the development after the development is removed (removed). The toner supplied by the supply roller 42 is attached to the surface of the developing roller 41 and before being conveyed to a developing area opposed to the surface of the photoreceptor 1, the amount of toner adhering to the developing roller 41 is appropriately pressed. The blade 43, which is a regulating member, regulates the amount of adhered toner and regulates the toner layer thickness to a constant value.

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 antinode on 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 metal spring blade 43 has the following characteristics.
Spring steel such as SUP, SUS301, S
Stainless steel such as US304, SUS420J2 and SUS631, 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 21, or to a value that is larger in absolute value.

On the other hand, the toner conveyed to the developing area 46 facing the photoreceptor 1 is selectively adhered in accordance with the electrostatic latent image formed on the surface of the photoreceptor 1, and changes the electrostatic latent image to the color of the toner. To 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 removal rod 44 having a circular cross section is pressed back to the developing roller 41 immediately after the return position, that is, immediately after the developing area 46 where the photosensitive member 1 and the developing roller 41 abut on the downstream side in the rotation direction of the developing roller 41. It is provided so as to be pressed against the developing roller 41. This removal rod 44
Is disposed in the rotation direction where the supply roller 42 and the developing roller 41 are pressed against each other.
Are driven to rotate in the same direction at the pressed position.

In order to remove the toner from the developing roller 41, the removing rod 44 is rotatably provided at both ends of the rod via a bearing or the like, and is movable toward the developing roller 41 via the bearing. It is provided as follows. The back surface of the removing rod 44, that is, the surface opposite to the position where it comes into contact with the developing roller 41 is pressed by the elastic plate 45, and is pressed against the surface of the developing roller 41 by the urging force of the elastic plate 45.

One end of the elastic plate 45 has the developing tank 4
0, and the removal rod 44 is
Is brought into pressure contact with the developing rod 41. The elastic plate 45 may be provided integrally with the developing tank 40. That is, the elastic plate 45 is
0, and the elasticity of the removal rod 45
Is pressed against the developing roller 41 side.

The removing rod 44 is formed, for example, in the shape of a round bar, and is made of a hard material such as metal or hard resin. here,
The diameter of the removal rod 44 of the present invention is reduced so that it can be provided as close as possible to the development area 46 as shown in the figure. The diameter is set to about several mm. Thus, it is possible to provide the photosensitive member 1 so as to be brought into close contact with the developing roller 41 immediately after the development without being brought into contact with the surface of the photoconductor 1 after the development.

The removing rod 44 is configured to receive rotation from a driving means other than the developing roller 41, for example, a motor, and is driven to rotate in a direction opposite to the rotating direction of the developing roller 41. Have been. Further, in order to efficiently remove the toner adhering to the developing roller 41 after the development, it is rotationally driven at a peripheral speed higher than the peripheral speed of the developing roller 41.

In the above configuration, the removal rod 4
4 is provided, and the developing roller 4 is driven to rotate.
It acts so as to remove the toner adhered to 1 after development. In particular, since the rotation direction is the same direction at the contact position with the developing roller 41 and the toner is rotated in the direction of scraping the toner into the developing tank 40, the scraped toner does not scatter.

Here, since the diameter of the removing rod 44 is very small, the sealing roller 6 having a shape as shown in FIG.
It seems that the effect of removing the toner is lower than that of the toner. However, the removing roller 4 having the smallest possible diameter is used.
4, the toner can be removed by pressing against the developing roller 41 near the developing area 46. As a result,
The toner can be reliably removed.

That is, in the developing area 46 where the developing roller 41 faces the photoconductor 1, the toner adhering to the developing roller 41 is removed by the developing bias and the electrostatic latent image formed on the photoconductor 1. The generated electric field tends to be attracted to the photoconductor 1 side. Therefore, the toner floats from the surface of the developing roller 41, and the adhesive force to the developing roller 41 is small and the toner is easily released. In particular, when an AC voltage is superposed on the developing roller 41 in a state where the toner of the developing roller 41 and the photoconductor 1 are not in contact with each other, the toner reciprocates between the photoconductor 1 and the developing area 46. It is in such a state.

Therefore, the development area 46 immediately after the development
When the removal rod 44 is pressed against the vicinity of the toner, the toner that is easily released can be easily removed from the developing roller 41. Further, even if the contact pressure of the removal rod 44 at that time is not increased, the removal efficiency is improved, and it is possible to reliably remove the toner while preventing the toner from being fused by a large pressure.

However, the residual toner adhering to the developing roller 41 gradually separates from the developing area 46, so that when the toner is largely separated from the photosensitive member 1, the developing roller 4
The adhesive force that adheres to one side gradually increases. Therefore, in order to remove the toner, it is necessary to increase the diameter of the seal roller and the like shown in FIG. 6 and increase the pressing force. As a result, the developing device tends to be large. In this regard, according to the present invention, as described above, the pressing force and the like can be reduced, so that damage to the toner and the like can be reduced, fusion and the like can be prevented, and the apparatus can be downsized.

Further, in the structure of the present invention, the removal rod 44 has an elastic plate 45 on the back surface of the developing roller 4.
If it is configured so as to be pressed into contact with the developer tank 1, it is in a sealed state in the developing tank 40, and the removed toner is not scattered. In addition, the toner adhering to the developing roller immediately after the development has a weak adhesive force, which may cause the toner to be scattered. However, the toner can be collected by the removing rod 44 in the developing tank 40 before the toner is scattered. Increase.

At this time, the bias voltage Vd can be supplied from the power supply circuit 14 to the removing rod 44 by keeping the removing rod 44 conductive. The bias voltage Va is set to a voltage value that is smaller in absolute value than the developing bias voltage Va supplied to the developing roller 41, and has the same polarity as the charged one-component toner. As a result, the removing effect can be further enhanced, and the toner immediately after development, which has a weak adhesive force to the developing roller 41, can be removed.
It can be shifted to the fourth side, and the collection efficiency can be increased. Further, by having the same polarity as the toner, strong adsorption of the toner to the removal rod 44 is prevented, and separation from the removal rod 44 can be easily performed.

(Other Embodiments of the Present Invention) As described above, in one embodiment of the present invention, the configuration in which the removing roller 44 is provided so as to approach immediately after the development by the developing roller 41, and the rotational direction and , The peripheral speed, and the relationship between the supplied bias voltage and the toner removal efficiency can be improved.

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

In order to enhance the effect of removing the toner, the position of the removing rod 44, the bias voltage (Vd), the rotation direction and the peripheral speed as described above, as well as the development of the removing rod 44 as shown in FIG. A scraping member 47 for scraping off the toner that has been removed by the removal rod 44 and is attached to the rotation rod downstream of the pressure contact position with the roller 41 is provided so as to be pressed against the removal rod 44.

The scraping member 47 has an L-shaped cross section as shown in FIG.
The end of the other side is fixed to the surface of the removing rod 44 so as to be pressed against the surface of the removing rod 44.

By providing such a scraping member 47, when the toner T remaining on and adhered to the developing roller 41 is removed by the removing rod 44 and collected in the developing tank 40,
The toner T adhered to the surface of the removal rod 44 can also be scraped off reliably. Then, the removing rod 44 is again pressed against the surface of the developing roller 41 in a clean state, and acts to increase the removing efficiency. In this case, the scraping member 4
One end of the fixing member 7 is fixed to the elastic plate 45 integrated with the developing tank 40, so that it also acts as a sealing member, and efficiently blows out and scatters the collected toner out of the developing tank 40. Can be prevented.

In this case, as described above, the removal rod 44
If the bias voltage Vd having the same polarity as that of the toner T is supplied to the toner, the scraping effect by the scraping member 47 is improved, and a further removing effect can be expected.

In FIG. 2, the scraping member 47 is provided at the downstream position where the residual toner of the developing roller 41 has been removed from the removing rod 44. However, as shown in FIG. An elastic member such as rubber having a cleaning function or a foam member 48 is provided between them. With this configuration, the pressure contact state between the removing rod 44 and the developing roller 41 is kept good, and the sealing property of the collected toner is improved. In addition, the cleaning of the surface of the removing rod 44 is also performed. You can do it at the same time.

In the structure shown in FIG. 3, the sealing effect is also enhanced as described with reference to FIG.
The toner adhering to the developing roller 41 can be removed and pressed against the developing roller 41 again in a clean state, so that the removing effect can be enhanced. Further, since the pressing of the removing rod 44 against the developing roller 41 can be assisted by the elastic member 48 or the like,
It is possible to maintain a stable pressure contact state, stabilize the removing action, and prevent the developing roller 41 from being damaged.

(Embodiment) An embodiment in which the effect of the structure shown in FIG. 1 has been confirmed will be described below.

The photosensitive member 1 was driven at a diameter of 65 mm and a peripheral speed of 190 mm / sec in the direction of arrow S1, and the photosensitive member surface potential was charged to -550V.

The developing roller 41 has a volume resistivity of about 10 MΩcm to which a conductive agent such as carbon black is added.
A conductive urethane rubber having a JIS-A hardness of 60 to 70 degrees and a diameter of 34 mm was used. This developing roller 41
Has a surface roughness of Rz = 3 to 6 μm (according to JIS B-0601), is brought into contact with the photoreceptor 1 via a toner layer at a contact depth of 0.1 to 0.3 mm, and has a peripheral speed of 285 mm in the direction of arrow S3. / Sec. A developing bias voltage Va of -450 V was supplied through a stainless steel shaft having a diameter of 18 mm of the developing roller 41.

The supply roller 42 has a volume efficiency of about 0.1 M
As a conductive foam roller having a diameter of 20 mm made of conductive urethane foam having an Ωcm, a cell density of 80 to 140 cells / inch, and an Asuka F hardness of 60 degrees to an Asuka C hardness of 30 degrees. The supply roller 42 is brought into contact with the developing roller 41 at a contact depth of 0.5 to 1 mm, and the peripheral speed 17 in the direction of arrow S2.
Rotation was performed at 0 mm / sec, and -550 V was supplied as a bias voltage Vc via a shaft having a diameter of 8 mm.

The blade 43, which is a regulating member, is a stainless steel plate having a thickness of about 0.1 mm and is 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.

The one-component toner includes 80 to 90 parts by weight of a styrene-acrylic copolymer and 5 to 1 parts of carbon black.
0 parts by weight, 0.5 to 1.5 parts by weight of silica as an external additive, and 0 to 5 parts by weight of an electrification control agent.
An uncharged toner having a size of 10 to 10 μm was used.

Then, the diameter of the removing rod 44 according to the present invention is made of metal having a diameter of about 3 mm, and is disposed close to the downstream side of the developing area 46 at a position about 10 mm downstream of the pressure contact between the photosensitive member 1 and the developing roller 41. To bring the developing roller 41 into pressure contact. The rotational speed of the removing rod 44 is set to a peripheral speed of 3
It was driven to rotate at 00 mm / sec, and a bias voltage of -300 V was supplied.

In such a configuration, the developing roller 4
It was confirmed that after the development of No. 1, the removal was efficiently performed by the removal rod 44. In particular, by using the developing roller 41 for a long time, it was confirmed that there was no evidence that the toner was adhered and fused, and stable development could be performed for a long time. Further, the provision of the removing rod 44 did not cause any damage to the surface of the developing roller 41.

In particular, even when the removal rod 44 is higher in hardness than the developing roller 41, the removal rod 44 is circular and has the same direction at the contact portion, so that there is no fear of scratching or the like. However, if the removing rod 44 is made of the same elastic rubber or the like as the developing roller 41, the nip at the pressure contact position with the developing roller 41 can be set longer, and the pressing force can be further reduced. Therefore, the toner removal efficiency is further increased, and the effect of preventing the developing roller 41 from being damaged is further enhanced.

The above-described developing device 4 has been described for developing with a single color, particularly, 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 the 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 high quality color image.

[0092]

According to the developing device using one-component toner of the present invention, the toner remaining after the development on the developing roller for developing can be efficiently removed, and the developing roller is damaged and the toner is fused. Etc. can be eliminated, and stable development can be performed over a long period of time.

Further, in removing the developing roller in the developing device, a removing rod is provided near the downstream side of the developing region, and by reducing the diameter of the removing rod as much as possible, the size of the developing device can be reduced. When the toner is removed by reducing the size of the toner, the toner can be removed in a state where the toner is separated from the developing roller by being located in the vicinity of the developing area, so that the efficiency is improved.

Further, the back surface of the removing rod is pressed against the developing roller by using an elastic plate,
It is possible to improve the efficiency of removal by improving the pressure contact, to enhance the sealing effect of preventing the toner from scattering after the removal, and to enhance the effect of preventing scattering.

[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 an enlarged view of a main part showing another aspect of one embodiment relating to post-processing of the removed toner by a removing roller for removing the toner remaining on the developing roller constituting the developing device shown in FIG. 1;

FIG. 3 is an enlarged view of a main part showing another mode of post-processing of the removed toner by a removing roller for removing the toner remaining on the developing roller constituting the developing device shown in FIG. 1 according to the embodiment;

FIG. 4 is a configuration diagram for explaining a configuration of a main part in an image forming unit in the image forming apparatus including the developing device having the configuration illustrated in FIG.

FIG. 5 is a diagram illustrating an example of a conventional developing device.

FIG. 6 is a diagram illustrating another example of a conventional developing device.

[Explanation of symbols]

Reference Signs List 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 14 power supply for supplying bias voltage Vd to removing roller Circuit 40 Developing tank 41 Developing roller 42 Supply roller 43 Blade (regulating member) 44 Removal rod 45 Elastic plate 46 Developing area 47 Scraping member 48 Elastic member

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 AD02 AD06 AD13 AD23 AD31 AD32 AD35 AD36 CA12 EA14 EA15 EA16 FA01 FA22 FA25

Claims (6)

[Claims] 1. A developing device comprising: a developing roller for carrying a one-component toner and transporting the toner to a developing area opposed to an electrostatic latent image carrier; A one-component toner developing device, comprising a rotatable removing rod pressed against the developing roller to remove the toner from the developing roller. 2. The removal rod has a circular section and a small diameter for providing immediately after the downstream side of the development area, and is provided such that the back surface thereof is pressed against the development roller by an elastic plate. The one-component toner developing device according to claim 1, wherein: 3. The removing rod is made of a conductive member, has the same polarity as the toner, and is supplied with a voltage lower in absolute value than the developing bias voltage supplied to the developing roller. The developing device for a one-component toner according to claim 1, wherein: 4. The apparatus according to claim 1, wherein the removing rod is driven to rotate in a direction opposite to a rotation direction of the developing roller and at a peripheral speed higher than a peripheral speed at which the developing roller is rotated. A one-component toner developing device. 5. A tip of a scraping member for scraping off toner adhered to the removal rod by pressing the removal rod downstream of the removal rod in the rotation direction of the removal rod with respect to the pressure contact position between the removal rod and the developing roller. 3. An apparatus according to claim 2, wherein said scraping member is fixed to said elastic plate. 6. An apparatus according to claim 2, wherein an elastic member is interposed between said removing rod and said elastic plate.