JPH1138748A - Developing device and toner supply - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toner feeder and a developing device equipped therewith, whereby it is practicable to charge electrostatically the toner without pressing to a developing roller any strongly. SOLUTION: A supply roller 27 as a toner feeder rotates in confronting a photo-sensitive drum 25 as a toner carrier, and polyimide grains are contained at in least the facial part of an elastic roll 36 which the supply roller 27 has. The content of polyimide grains can enhance the chargeability of the toner to be put in touch between the supply roller 27 and developing roller 26.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device, and more particularly, to a developing device provided in an image forming apparatus such as a copying machine, a laser printer, and a facsimile, and a toner supply member provided in the developing device.

[0002]

2. Description of the Related Art A developing device provided in an image forming apparatus of this type, such as a copying machine, a laser printer, and a facsimile, includes:
The image forming apparatus includes a photosensitive drum on which an electrostatic latent image is formed, a developing roller that carries toner and supplies toner to the photosensitive drum, and a supply roller that supplies toner to the developing roller. The surface of the photoreceptor drum is charged by a charger, and a laser beam based on predetermined image data is irradiated on the surface of the photoreceptor drum by high-speed scanning to form an electrostatic latent image. Further, the developing roller is arranged so as to be in contact with the photosensitive drum, and is applied with a bias voltage having a constant voltage so that the toner carried from the developing roller is directed toward the electrostatic latent image.
The supply roller is made of a foam, and is arranged so as to be in contact with the developing roller in a state where the foam is compressed to some extent. Then, the toner contained in the toner box is sent to the developing roller by the rotation of the supply roller, and is brought into contact with these rollers between the supply roller and the development roller to be charged. The toner supplied onto the developing roller is carried in a thin layer on the surface of the developing roller by a blade or the like arranged on the side of the developing roller.
When the charged toner contacts the photosensitive drum by the rotation of the developing roller, the charged toner adheres to the electrostatic latent image formed on the photosensitive drum, and the toner is developed. The toner adhered on the photosensitive drum is then transferred to a sheet to achieve a predetermined printing.

[0003]

However, in such a developing device, the toner needs to be sufficiently charged in order to develop the toner satisfactorily. If the poorly charged toner is on the developing roller, when the toner is developed, the poorly charged toner adheres to an area other than the image formed by the electrostatic latent image, which may cause a development failure. is there.

On the other hand, in order to carry sufficiently charged toner on the developing roller, it is necessary to sufficiently contact the toner between the supply roller and the developing roller by bringing the toner into contact with these rollers to sufficiently perform triboelectric charging. For this purpose, it is necessary to strongly press the supply roller against the developing roller. However, if the supply roller is pressed too strongly against the developing roller, the developing roller is scratched, which causes a development defect such as a vertical streak.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems, and a toner supply member capable of sufficiently charging a toner without strongly pressing a developing roller. Another object of the present invention is to provide a developing device including the toner supply member.

[0006]

According to one aspect of the present invention, there is provided a toner carrier for supplying a toner to a latent image carrier on which an electrostatic latent image is formed, A toner supply unit for supplying toner to the carrier, the toner supply unit has an elastic roll that rotates facing the toner carrier, at least a surface portion of the elastic roll, It is characterized by containing polyimide particles. By containing polyimide particles at least on the surface of the elastic roll,
The chargeability of the toner contacted between the toner carrier and the toner supply can be improved. Therefore, it is possible to carry well charged toner on the toner carrier without strongly pressing the toner supply body against the toner carrier. Accordingly, the amount of toner having poor charging can be reduced, and the occurrence of developing failure of toner can be suppressed. Further, since it is not necessary to strongly press the toner supply member against the toner carrier, the toner carrier is not damaged, and development defects such as vertical stripes due to the scratch are less likely to occur. Furthermore, by containing polyimide particles, the abrasion resistance of the elastic roll can be improved. Therefore, a state in which the toner can be favorably charged can be maintained for a long time.

[0007] The invention described in claim 2 is the first invention.
In the invention described in (1), the elastic roll is made of a silicone foam or a urethane foam. When the elastic roll is made of a silicone foam or a urethane foam, the abrasion resistance and heat resistance of the elastic roll are improved, so that the toner has good abrasion resistance and heat resistance while ensuring good chargeability of the toner. An excellent elastic roll can be obtained.

[0008] The invention described in claim 3 is the first invention.
In the invention described in (2), the polyimide particles have a particle diameter of 10 μm or less. If the particle diameter of the polyimide particles exceeds 10 μm, the particle diameter may be larger than the particle diameter of the toner, and the toner carrier facing the elastic roll may be damaged. Therefore, by using polyimide particles having a particle size of 10 μm or less, it is possible to obtain an elastic roll that can charge the toner satisfactorily without damaging the toner carrier and that is excellent in abrasion resistance and the like. .

According to a fourth aspect of the present invention, there is provided a toner supply member for supplying toner to a toner carrier for supplying toner to a latent image carrier on which an electrostatic latent image is formed,
The toner supply body has an elastic roll that rotates in opposition to the toner carrier, and at least a surface portion of the elastic roll contains polyimide particles. By including the polyimide particles in at least the surface portion of the elastic roll, it is possible to improve the chargeability of the toner contacted between the toner carrier and the toner supplier. Therefore, the well-charged toner can be carried on the toner carrier without strongly pressing the toner supply body against the toner carrier. Therefore,
Poorly charged toner can be reduced, and poor toner development can be prevented. Further, since it is not necessary to strongly press the toner supply member against the toner carrier, the toner carrier is not damaged, and development defects such as vertical stripes due to the scratch are less likely to occur. Further, by containing the polyimide particles, the abrasion resistance can be improved.
Therefore, a state in which the toner can be favorably charged can be maintained for a long time.

[0010]

FIG. 1 is a side sectional view showing a main part of an embodiment of a laser printer provided with a developing device of the present invention. In FIG. 1, a laser printer 1 includes a main body case 2, a first paper feed tray 3, a second paper feed tray 4 provided on a rear upper side of the main body case 2, and a paper transport mechanism 5 provided in the main body case 2. , A scanner unit 6, a process unit 7 as a developing device, a fixing unit 8 and the like. The scanner unit 6, the process unit 7 and the fixing unit 8 constitute a printing unit for printing on paper. Also, on the upper front side of the main body case 2, a top cover 10 capable of opening the upper surface side of the printing unit, and openable and closable between a closed position and an open position, and the printed paper 14 is opened and closed at the open position. A receiving tray 11 is provided.

First paper tray 3 and second paper tray 4
Can be detachably attached to the main body case 2, can set the paper 14 in a stacked state, and picks up a pickup roller 9 for feeding the stacked paper 14 one by one.
Are provided. The paper transport mechanism 5 is for transporting the paper 14 selectively fed from the first paper feed tray 3 and the second paper feed tray 4 to the process unit 7. It has a pair of feed rollers 12 provided on the lower end side and a pair of registration rollers 13 provided on the lower end side of the second paper feed tray 4.

The paper 14 fed from the first paper feed tray 3 by the pickup roller 9 is a pair of feed rollers 12
Is transferred to the pair of registration rollers 13, and after a predetermined registration, is conveyed to the process unit 7 by driving the registration rollers 13. The paper 14 fed from the second paper feed tray 4 by the pickup roller 9 is
After the predetermined registration, the sheet is conveyed to the process unit 7 by driving the registration roller 13.

The scanner unit 6 is disposed below the process unit 7 and includes a laser light emitting unit (not shown), a polygon mirror 20, reflection mirrors 21 and 23, a lens 22, and the like. Then, a laser beam based on predetermined image data emitted from the laser emitting section is passed or reflected in the order of the polygon mirror 20, the reflecting mirror 21, the lens 22, and the reflecting mirror 23 as shown by a chain line, and will be described later. Irradiation is performed on the surface of the photosensitive drum 25 of the process unit 7 by high-speed scanning.

FIG. 2 is an enlarged side sectional view showing a process unit 7 as a developing device. Next, the process unit 7 will be described with reference to FIG. 2, a process unit 7 includes a photosensitive drum 25 as a latent image carrier, a developing roller 26 as a toner carrier, a supply roller 27 as a toner supplier, a scorotron charger 28, a transfer roller 29, a cleaning roller 30, a toner box 31, and the like are housed, and have a cartridge structure that can be attached to and detached from a predetermined portion in the main body case 2. And this process unit 7
The toner can be supplied by attaching the toner cartridge 32 to the toner box 31 in a state in which is removed from the main body case 2. The toner in the toner cartridge 32 is agitated by the agitator 34 and discharged from the toner supply port 33 opened on the side of the toner box 31. The toner used here is a non-magnetic one-component toner. A supply roller 27 is rotatably disposed at a side position of the toner supply port 33, and a developing roller 26 is rotatably disposed opposite to the supply roller 27. Supply roller 27
Is a metal roller shaft 35 formed of various steel materials.
And an elastic roll 3 covering the periphery of the roller shaft 35.
The elastic roll 36 is formed of a conductive foam. The developing roller 26 has a metal roller shaft 37 made of various steel materials and an elastic roll 38 covering the periphery of the roller shaft 37. It is formed of a conductive rubber body that is harder than the body. And the supply roller 27
The elastic roll 36 is in contact with the elastic roll 38 of the developing roller 26 while being compressed to some extent.

On the other hand, the photosensitive drum 25 is
Is in contact with the developing roller 26 at a lateral position, and is rotatably disposed. Also, the photosensitive drum 25
Is charged by a scorotron-type charger 28 and is exposed by the high-speed scanning of the laser beam from the scanner unit 6 described above, and is statically based on predetermined image data. An electrostatic latent image is formed.

The toner discharged from the toner supply port 33 is supplied to the developing roller 2 by the rotation of the supply roller 27.
6 and is carried as a thin layer having a constant thickness on an elastic roll 38 of the developing roller 26 by a blade 39 disposed on the side of the developing roller 26. At this time, the toner supplied to the developing roller 26 is moved between the elastic roll 36 of the supply roller 27 and the elastic roll 38 of the developing roller 26.
The elastic rolls 36 and 38 come into contact with each other and are charged by friction. The shaft 37 of the developing roller 26 includes
A bias voltage of a constant voltage is applied by a constant voltage DC power supply device (not shown) so that the toner carried from the elastic roll 38 of the developing roller 26 is directed to the electrostatic latent image on the photosensitive drum 25. Then, when the toner carried on the elastic roll 38 of the developing roller 26 comes into contact with the photosensitive drum 25 due to the rotation of the developing roller 26, the toner forms an electrostatic latent image formed on the surface of the photosensitive drum 25. The toner is developed by attaching to the image. Beside the photosensitive drum 25, this photosensitive drum 25
Is provided, and the toner attached to the electrostatic latent image is transferred to the paper 14 while the paper 14 passes between the photosensitive drum 25 and the transfer roller 28, and the paper 14 is Is sent into the fixing unit 8 and is fixed.

The toner remaining on the surface of the photosensitive drum 25 is temporarily recovered by the cleaning roller 30 and then recovered by the developing roller 26 via the photosensitive drum 25 at a predetermined timing. Also, the toner box 3
Two auger members 40 and 41 are rotatably disposed in the vicinity of the first toner supply port 33, and each auger member 40 and 41 transfers the toner discharged from the toner supply port 33 to the inside of the casing 24. So that it is evenly dispersed.

The fixing unit 8, as shown in FIG. 1, heat-fixes the toner transferred to the paper 14, and
A heating roller 42, a pressing roller 43 pressed by the heating roller 42, and a pair of discharge rollers 44 provided downstream of the rollers 42 and 43 for discharging the paper 14 to the outside of the main body case 2. Equipped, heating roller 42
After the transferred toner is thermally fixed by the pressing roller 43, the toner is discharged onto the discharge tray 11 by the discharge roller 44.

In this embodiment, in the present embodiment, the elastic roll 36 of the supply roller 27 is made of a silicone foam or a urethane foam, and at least the surface of the foam has polyimide particles. Is contained. The silicone foam or urethane foam can be obtained by a known foam molding method using a known raw material. Further, to contain the polyimide particles, when foaming a silicone foam, or a urethane foam, the foaming material of the silicone foam, or the foaming material of the urethane foam, the polyimide particles are compounded by kneading or the like. Then, it can be contained by foaming with these raw materials. In the foam thus obtained, the polyimide particles exist in a dispersed state. By dispersing the polyimide particles in the foam, even if the surface portion is worn by long-term use, the polyimide particles are not eliminated and the durability can be improved. The polyimide particles may be added to a foaming raw material at the time of foaming, or may be impregnated into a foam after foaming by a known method. This impregnation is performed, for example, by immersing the foam in an impregnation liquid prepared by dispersing polyimide particles in advance and then drying the foam. In this case, the polyimide particles
Retained on the surface of the foam. According to the impregnation method, polyimide particles can be easily and reliably contained in the surface of the foam. The polyimide particles to be contained preferably have a particle size of 10 μm or less. When the particle size of the polyimide particles exceeds 10 μm,
The toner may be larger than the particle diameter of the toner, and the developing roller 26 may be damaged. Therefore, the developing roller 2 is made of polyimide particles having a particle size of 10 μm or less.
6 is not damaged.

As described above, by containing the polyimide particles in the elastic roll 36 of the supply roller 27, the elastic roll 36 of the supply roller 27 and the elastic roll 3 of the developing roller 26 are formed.
8, the chargeability of the toner contacting these elastic rolls 36 and 38 can be improved. Therefore, even if the supply roller 27 is not strongly pressed against the developing roller 26, the well-charged toner can be carried on the elastic roll 38 of the developing roller 26.
Accordingly, the amount of toner having poor charging can be reduced, and the occurrence of developing failure of toner can be suppressed. Further, since the supply roller 27 does not need to be strongly pressed against the developing roller 26, the developing roller 26 is not damaged, and development defects such as vertical stripes due to the damage are less likely to occur. Further, by containing the polyimide particles in the elastic roll 36 of the supply roller 27, the wear resistance of the elastic roll 36 can be improved. Therefore, a state in which the toner can be favorably charged can be maintained for a long time. Therefore,
It is possible to obtain the process unit 7 in which poor development hardly occurs and which has excellent durability.

The elastic roller 36 of the supply roller 27
Is made of a silicone foam or a urethane foam, the abrasion resistance and heat resistance of the elastic roll 36 can be improved. Therefore, it is possible to obtain the elastic roll 36 having excellent abrasion resistance and heat resistance while ensuring good chargeability of the toner, and to obtain the process unit 7 which is less likely to cause poor development and has more excellent durability. be able to.

[0022]

As described above, according to the first aspect of the present invention, since the toner supply member which can charge the toner satisfactorily and can maintain the state for a long time is provided. It is possible to obtain a developing device that hardly causes poor development and has excellent durability.

According to the second aspect of the present invention, it is possible to provide a toner supply member having excellent abrasion resistance and heat resistance while ensuring good charging properties of the toner. In addition, a developing device having higher durability can be obtained. According to the third aspect of the present invention, it is possible to provide a toner supply member capable of satisfactorily charging the toner without damaging the toner carrying member. And a developing device having excellent performance can be obtained.

According to the fourth aspect of the present invention, it is possible to obtain a toner supply member which can charge the toner satisfactorily and maintain the state for a long period of time.

[Brief description of the drawings]

FIG. 1 is a side sectional view showing a main part of an embodiment of a laser printer including a developing device of the present invention.

FIG. 2 is an enlarged side sectional view showing a process unit.

[Explanation of symbols]

 7 Process Unit 25 Photosensitive Drum 26 Developing Roller 27 Supply Roller 36 Elastic Roll

Claims (4)

[Claims] 1. A developing device, comprising: a toner carrier for supplying toner to a latent image carrier on which an electrostatic latent image is formed; and a toner supplier for supplying toner to the toner carrier. The developing device is characterized in that the toner supply body has an elastic roll that rotates to face the toner carrier, and at least a surface portion of the elastic roll contains polyimide particles. 2. The elastic roll comprises a silicone foam,
The developing device according to claim 1, wherein the developing device is made of a urethane foam. 3. The polyimide particles having a particle size of 10 μm.
The developing device according to claim 1, wherein: 4. A toner supply for supplying toner to a toner carrier that supplies toner to a latent image carrier on which an electrostatic latent image is formed, wherein the toner carrier is the toner carrier. A toner supply body having an elastic roll that rotates in opposition to the above, wherein at least a surface portion of the elastic roll contains polyimide particles.