JP2002229349A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a photoreceptor drum from being vibrated by an impact made when recording paper is inserted in and ejected from space between the photoreceptor drum and a transfer roller. SOLUTION: A 1st regulating member 22 is provided separately from the photoreceptor drum 12 on a drum shaft 21, and a 2nd regulating member 23 is provided separately from the transfer roller 16 on a roller shaft 25, then the peripheral surfaces of the members 22 and 23 are made to abut on each other. Thus, displacement amount with the impact made when the recording paper 19 is inserted in the space between the drum 12 and the roller 16 is reduced, and the vibration applied to the drum 12 is reduced. Thus, a toner image formed on the drum 12 and an unfixed toner image transferred to the recording paper 19 are not vibrated, whereby image irregularity and image blur are prevented and the excellent image is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic image forming apparatus such as a copying machine, a facsimile, a printer, and the like, and more particularly, to an image carrier and a transferer arranged in a predetermined positional relationship with the image carrier. The present invention relates to a configuration of a roller.

[0002]

2. Description of the Related Art An image forming apparatus transfers a toner image formed on a photosensitive drum onto a recording sheet and forms an image on the recording sheet. Conventionally, a high quality printed image can be obtained. There is a need for an image forming apparatus.

FIG. 6 shows a part of a conventional image forming apparatus 1, FIG. 6 (1) shows a sectional view, and FIG. 6 (2) shows a simplified model. As shown in FIG. 6A, the photosensitive drum 2 has a hollow cylindrical photosensitive drum tube portion 4.
3 and a pair of drum flanges 6 that close the openings at both ends of the photosensitive drum tube portion 43. A drum shaft 8 that penetrates the photosensitive drum 2 in the axial direction is a photosensitive drum 2
The drum shaft 8 is rotatably supported by a pair of drum-side bearings 40 provided at both ends.

The transfer roller 3 is formed in a cylindrical shape, and its axis A2 is arranged parallel to the axis A1 of the photosensitive drum 2. A roller shaft 7 that penetrates the transfer roller 3 in the axial direction;
Is formed coaxially with the transfer roller 3, and the roller shaft 7 is rotatably supported by a pair of roller-side bearings 42 provided at both ends. The roller shaft 7 is connected to a pair of resilient urging members 5 in the axial direction, and is provided with a pair of tracking rolls 4 in the axial direction, and a restricting means according to the present invention. The roller shaft 7 is pressed toward the drum shaft 8 by the urging member 5, and each tracking roll 4 comes into contact with the photosensitive drum 2, so that a predetermined amount of space is provided between the photosensitive drum 2 and the transfer roller 3. Gap H
Is formed. Such a conventional image forming apparatus 1
Is disclosed in JP-A-9-218549.

In such an image forming apparatus 1, since a gap is formed between the peripheral surface of the photosensitive drum and the peripheral surface of the transfer roller, the photosensitive drum and the transfer roller do not slide, and the photosensitive member does not slide. The photosensitive layer on the peripheral surface of the drum is prevented from being worn and peeled off, and the toner image can be satisfactorily transferred to the recording paper to prevent image disturbance.

Further, in addition to the image forming apparatus in which a predetermined amount of gap is formed between the peripheral surface of the photosensitive drum and the peripheral surface of the transfer roller by the restricting means such as a tracking roll as described above, a restricting means is also provided. There is an image forming apparatus configured to press the peripheral surface of the photosensitive drum and the peripheral surface of the transfer roller with a predetermined pressing force. Such a conventional technique is disclosed in Japanese Unexamined Patent Application Publication No.
No. 65173.

In such an image forming apparatus, since the peripheral surface of the photosensitive drum is in contact with the peripheral surface of the transfer roller,
Since the peripheral surface of the photosensitive drum and the peripheral surface of the transfer roller are pressed against each other with a stable predetermined pressure contact force, the transfer electric field (or potential difference) acting between the peripheral surface of the photosensitive drum and the peripheral surface of the transfer roller is greatly increased. The toner image can be satisfactorily transferred to the recording paper without any need and without a problem such as a missing character due to a high pressing force.

[0008]

SUMMARY OF THE INVENTION An outer peripheral surface of an image carrier such as a photosensitive drum, a photosensitive belt and an intermediate transfer member for carrying a toner image, and a transfer roller for transferring the toner image on the image carrier onto a recording paper In the above-described related art in which the positional relationship with the peripheral surface is regulated by the urging member and the regulating means such that the positional relationship with the peripheral surface becomes a predetermined positional relationship, there are the following problems.

When recording paper is inserted between the surface of the image carrier and the surface of the transfer roller, the positional relationship between the photosensitive drum and the transfer roller is determined by the relationship between the surface of the image carrier and the surface of the transfer roller. When the recording paper is discharged from the surface of the image carrier and the surface of the transfer roller, the recording paper is returned to the original position by the urging member. At this time, an impact force acts on the image carrier by inserting and discharging the recording paper. In particular, when a thick recording paper or a recording paper having irregularities is inserted, the impact force becomes large.

[0010] When such an impact force acts, the image carrier is displaced in a short time, and the toner image carried on the image carrier and the unfixed toner image transferred to the recording paper are vibrated. There is a problem in that blurring of an image, blurring of an image, and the like occur, and a high-quality image cannot be obtained. In particular, when the image carrier, the transfer roller, and the like are formed of a hollow body, the vibration of the image carrier becomes larger when an impact force acts on the outer peripheral surface of the hollow portion.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention has been made in view of the above-mentioned problems. Even if there is an impact generated when a recording sheet is inserted and ejected, the image carrier and the recording sheet are not vibrated. It is an object of the present invention to provide an image forming apparatus capable of performing an excellent transfer.

[0012]

According to the present invention, there is provided an image carrier for carrying a toner image, the image carrier being urged toward the image carrier and having a predetermined positional relationship with the image carrier by a regulating means. In the image forming apparatus having the transfer roller disposed, the regulating unit is provided to be spaced apart from an axial end of the image carrier and between the transfer roller axis and the image carrier axis. An image forming apparatus characterized in that:

According to the present invention, the image carrier and the transfer roller are positioned in a predetermined positional relationship by the regulating device, and the regulating device is provided axially outward of the image carrier. Therefore, the amount of displacement of the image carrier due to the impact force at the time of inserting and discharging the recording paper can be reduced. This will be described with reference to FIGS.

FIG. 1 shows a part of an image forming apparatus 10 according to an embodiment of the present invention, and FIG.
(2) shows a simplified model.

As shown in FIGS. 1 (1) and 6 (1), in order to compare the conventional apparatus with the apparatus of the present invention, for example, the position of the regulating means disposed on the axis of the image carrier, for example, the photosensitive The dimensions of the body drum, the bearing position, the characteristics of the urging means, the dimensions of the drum shaft, and the material of each member are the same in the conventional apparatus and the apparatus of the present invention. In the conventional device 1, the regulating means 4 is in contact with the outer periphery of the photosensitive drum 2, and is provided with the roller-side bearing 40 and predetermined dimensions L1 and L2. On the other hand, in the apparatus 10 of the present invention, the regulating means 50 is separated from the photosensitive drum 12 and provided with the roller-side bearing 28 and predetermined dimensions L3 and L4. Therefore, the dimension between the roller-side bearing and the regulating means is shorter in the dimensions L3 and L4 of the apparatus of the present invention than in the dimensions L1 and L2 of the conventional apparatus.

The magnitude of the impact force generated when the recording paper is inserted and ejected depends on how much the transfer roller is displaced from the axis of the photosensitive drum. Therefore, when the thickness of the recording paper is the same, the magnitude of the impact force generated in the image forming apparatuses of the related art and the present invention is the same. However, since an impact force is generated at the position of the regulating means for regulating the positions of the photosensitive drum and the transfer roller, the position of the impact force is different between the case of the prior art and the case of the present invention.

Therefore, as shown in FIGS. 1 (2) and 6 (2), the dimensions L3 and L4 between the bearing and the regulating member in the present invention are shorter than the dimensions L1 and L2 in the conventional case. The moment around the bearing due to the force F is smaller in the present invention. Therefore, the deflection of the drum shaft due to the impact force F is smaller in the present invention, and the displacement amount and the vibration of the surface of the photosensitive drum carrying the toner image are smaller than in the prior art.

As described above, according to the present invention, the displacement and vibration of the image carrier can be reduced when the impact force due to the passage of the recording paper is applied, and the toner image on the image carrier is favorably printed on the recording paper. Can be transferred to

In addition, in the image forming apparatus of the present invention, it is not necessary to lengthen the size of the image carrier in the axial direction in order to abut the regulating member. Can be reduced, and the cost of a consumable but expensive image carrier can be reduced.

Further, the invention is characterized in that the regulating means is made of a material that absorbs impact.

According to the present invention, since the restricting means is made of a shock absorbing material, the restricting means absorbs a shock when the recording paper is inserted and discharged, and reduces a shock applied to the image carrier and the recording paper during image transfer. can do.

According to the present invention, the restricting means includes a first restricting member loosely fitted on a shaft of the image carrier and a second restricting member loosely fitted on a shaft of the transfer roller. Have
The first and second regulating members are in contact with each other.

According to the present invention, the first and second regulating members are provided so as to be loosely fitted to the shafts of the image carrier and the transfer roller, respectively. The first and second regulating members can be kept stationary without rotating in a state where they are in contact with each other. Therefore, each regulating member does not rotate together with the image carrier and the transfer roller, and the abutment surface of each regulating member is prevented from being worn. Further, foreign matter such as toner does not easily adhere to the contact surfaces of the respective regulating members, and an accurate predetermined positional relationship between the image carrier and the transfer roller can be formed.

Further, the present invention is characterized in that the restricting means is provided at a position outwardly separated from an axial end of the transfer roller.

According to the present invention, since the regulating means is provided apart from the end of the transfer roller, the amount of displacement of the transfer roller due to the impact force can be reduced when the recording paper is inserted and ejected.

[0026]

FIG. 2 is a sectional view showing a main structure of an image forming apparatus 10 according to one embodiment of the present invention. The image forming apparatus 10 is an electrophotographic system such as a copying machine or a printer.
This is an apparatus for forming an image on a recording sheet, and a mechanism for forming an image on the recording sheet is provided around a photosensitive drum 12 which is an image carrier. A charging mechanism 13 for uniformly charging the surface of the photoconductor drum 12, an exposure mechanism 14 for irradiating light for forming an electrostatic latent image on the surface of the photoconductor drum 12, A developing mechanism 15 for supplying toner to the electrostatic latent image formed on the surface of the photosensitive drum to form a toner image, and a transfer mechanism for transferring the toner image formed on the surface of the photosensitive drum to recording paper as a recording medium A roller 16, a cleaning blade 17 for cleaning the surface of the photosensitive drum, and a charging lamp 18 for removing residual charges on the surface of the photosensitive drum are arranged side by side.

In order to form an image in the image forming apparatus 10, first, the surface of the photosensitive drum 12 is charged to the charging mechanism 1.
3, an electrostatic latent image is formed by irradiating the charged photosensitive drum surface with a laser beam by an exposure mechanism 14 and a developing mechanism 15 supplies toner to the electrostatic latent image. A toner image is formed, the toner image is transferred onto a recording sheet sent between the transfer roller 16 and the photosensitive drum 12, and the recording sheet is heated by a heat fixing mechanism (not shown), and the toner image is transferred onto the recording sheet. Fix it.

The toner remaining on the surface of the photosensitive drum after the image transfer is removed by the cleaning blade 17.
The charge remaining on the surface of the photoreceptor drum is gradually charged by the slow charging lamp, and the image forming apparatus is prepared for the next image formation.

FIG. 3 is a cross-sectional view showing the vicinity of the transfer roller of the image forming apparatus 10 as viewed from the recording paper insertion side. As shown in FIGS. 1 and 3, the image forming apparatus 10 includes a photosensitive drum 12, a flange 20, a transfer roller 16, a first regulating member 22, a second regulating member 23, and an urging member 24.

The photosensitive drum 12 includes a photosensitive drum base 12a and a photosensitive drum base 1 formed in a hollow cylindrical shape.
2a is formed by a pair of drum flanges 20 closing the openings at both ends. A drum shaft 21 penetrating through the photosensitive drum 2 in the axial direction is formed coaxially with the photosensitive drum 12, and the drum shaft 21 is rotatably supported by a pair of drum-side bearings 28 provided at both ends.

The transfer roller 16 is formed in a cylindrical shape, and its axis A4 is arranged parallel to the axis A3 of the photosensitive drum 12. A roller shaft 25 that passes through the transfer roller 16 in the axial direction is formed coaxially with the transfer roller 16, and the roller shaft 7 is rotatably supported by a pair of roller-side bearings 29 provided at both ends. The roller-side bearing 29 is
The image forming apparatus 1 is mounted in the long hole 30 of the frame 27. The roller-side bearing 29 is formed by the long hole 30 so that the drum shaft 21
, Whereby the roller shaft 25 supported by the roller-side bearing 29 is supported so as to be able to approach and separate from the drum shaft 21. Therefore, in the embodiment, the transfer roller 16 is disposed below the photosensitive drum 12 and is supported so as to be able to move up and down.

A gear b is fixed to one end of the drum shaft 21 and meshes with a gear a to which a rotational force is transmitted from a rotation transmitting mechanism (not shown). As a result, the rotational force from the rotation transmission mechanism is transmitted to the photosensitive drum 12 via the gear a, the gear b, and the drum shaft 21. One of the flanges attached to the photosensitive drum 12;
That is, the gear groove 40 is formed on the peripheral surface of the flange 20 on the side where the gear b is formed.

A gear d is fixed to one end of the roller shaft 25. The gear d meshes with the gear groove 40 formed in the aforementioned flange. Thereby, the photosensitive drum 1
2 is transmitted to the transfer roller 16. Therefore, the transfer roller 16 rotates in synchronization with the photosensitive drum 12, and
The inserted recording paper can be pinched and discharged.

The biasing members 24 are provided on the pair of roller shaft side bearings 29, respectively. The urging member 24 has elasticity, and is configured by, for example, a spring. As a result, the urging member 24 presses the transfer roller 16 toward the photosensitive drum 12.

FIG. 4 is a front view showing a part of the image forming apparatus 10 of FIG. The first regulating member 22 and the second regulating member 23, which are regulating means 50, are formed in a disk shape, and are provided on both sides of the photosensitive drum 12 and the transfer roller 16, respectively. By the urging member 24,
The roller shaft 25 is urged toward the drum shaft 21 and the first
A predetermined gap H is formed between the photosensitive drum 12 and the transfer roller 16 by the contact between the regulating member 22 and the second regulating member 23. The predetermined gap H is set smaller than the thickness of the recording paper.

The first regulating member 22 is provided for the photosensitive drum 12
Is loosely fitted to the drum shaft 21 at a position separated from the drum shaft 21. Similarly, the second regulating member 23 is loosely fitted to the roller shaft 25 at a position separated from the transfer roller 16 in a rotatable state. Also, the first regulating member 22
The second regulating member 23 has a shock absorbing means and is made of a resilient shock absorbing material such as resin or hard rubber.

FIG. 5 is a side view of FIG. 4, and FIG.
5 shows a state before the recording paper 19 is inserted, and FIG. 5B shows a state where the recording paper 19 is inserted. As shown in FIG. 5A, the recording paper 19 is composed of the photosensitive drum 12 and the transfer roller 1.
6 and is inserted between the photosensitive drum 12 and the transfer roller 16 as shown in FIG. At this time, since the thickness of the recording paper 19 is larger than the gap H between the photosensitive drum 12 and the transfer roller 16, the transfer roller 12 is separated from the photosensitive drum 12,
The distance between the photosensitive drum 12 and the transfer roller 16 increases, and the first regulating member 22 and the second regulating member 23 separate from each other. The transfer roller 16 is pressed by the urging member 24 so as to approach the photosensitive drum 12, and the recording paper 19 passes between the photosensitive drum 12 and the transfer roller 16 against this pressing force. . When discharging, the urging member 2
The first regulating member 22 and the second regulating member 23 come into contact again by the spring force of 4, and the distance between the photosensitive drum 12 and the transfer roller 16 returns to the predetermined gap dimension H.

That is, an impact occurs when the recording paper is inserted and ejected, but the first regulating member 22 and the second regulating member 2
3 is mounted at a position separated from the photosensitive drum 12 and the transfer roller 16, respectively, so that the moment acting due to the impact force can be reduced, and the radius of the photosensitive drum and the transfer roller can be reduced. Further, since the first and second regulating members are formed of a shock absorbing material, the impact force and the vibration due to the impact force are absorbed. In this manner, the vibration applied to the photosensitive drum 12 and the recording paper 19 is reduced.
The toner image formed on the recording paper and the unfixed toner image transferred to the recording paper are not vibrated, preventing image blurring and image blurring, and forming a good image.

Further, since the first regulating member 22 and the second regulating member 23 are provided so as to be loosely fitted to the drum shaft 21 and the roller shaft 25, respectively, even if the drum shaft 21 and the roller shaft 25 rotate, the first regulating member 22 and the second regulating member 23 are rotated. The first regulating member 22 and the second regulating member 23 can stand still in a contact state without rotating. Therefore, the first regulating member 22 and the second regulating member 23 do not rotate together with the photosensitive drum 12 and the transfer roller 16, and the contact surfaces of the first regulating member 22 and the second regulating member 23 are worn. Is prevented. Further, it is possible to form an accurate and constant gap H between the photosensitive drum 12 and the transfer roller 16 without foreign matters such as toner adhering to the contact surface.

The above embodiment is merely an example of the invention, and the configuration can be changed within the scope of the invention. For example, in this embodiment, the regulating means is used so as to form a predetermined gap H between the photosensitive drum as the image carrier and the transfer roller. However, the present invention is not limited to this. For example, the invention also includes an image forming apparatus that regulates the image bearing member and the transfer roller by a regulating unit such that the transfer roller is pressed against the image carrier at a predetermined pressure.

In the present embodiment, the first regulating member and the second regulating member are brought into contact with each other to regulate the photosensitive drum and the transfer roller in a predetermined positional relationship. However, one regulating member is used. It may be restricted to a predetermined positional relationship. For example, by contacting the first regulating member with the shaft of the transfer roller, or by contacting the second regulating member with the shaft of the image carrier, the photosensitive drum and the transfer roller are regulated in a predetermined positional relationship. Is also good.

At least one of the first and second regulating members does not have to be provided directly on the shaft, but may be disposed between the axes A1 and A2 of the photosensitive drum and the transfer roller. Provide another member that is coaxial,
It may be provided between the axes A1, A2 via this member. Further, the first and second regulating members do not necessarily have to be disc-shaped, and may have other shapes.

Although the image bearing member has been described as an example of a photosensitive drum, it may be a photosensitive belt or an intermediate transfer member. In the case of the photoreceptor belt, a regulating means is provided between an axis of a shaft facing the transfer roller and an axis of the transfer roller among a plurality of shafts for rotating the photoreceptor belt without loosening.

[0044]

According to the present invention, it is possible to reduce the amount of displacement of the image carrier and the vibration applied to the image carrier itself when an impact force due to the passage of the recording paper acts. This prevents image blurring that occurred when inserting and ejecting recording paper,
Good image quality can be obtained.

Further, since the dimension of the image carrier for contact with the regulating means is not lengthened in the axial direction, the dimension of the image carrier in the axial direction can be reduced. The cost of the image carrier can be reduced.

Further, according to the present invention, since the regulating means can absorb the impact, the impact applied to the image carrier and the recording paper during the image transfer can be further reduced. Thereby, better image quality can be obtained.

Further, according to the present invention, since the abrasion of the contact surfaces where the first and second regulating members contact each other and the adhesion of foreign matter are prevented, an accurate constant distance between the image carrier and the transfer roller is ensured. Can be formed. As a result, a stable pressing force can be applied to the recording paper during image transfer,
The toner image can be transferred onto the recording paper without unevenness.

Further, according to the present invention, since the regulating means is provided apart from the end of the transfer roller, the displacement of the transfer roller due to the impact force can be reduced. As a result, it is possible to further reduce image blurring or the like that has occurred when the recording paper is inserted and ejected.

[Brief description of the drawings]

FIG. 1 shows a part of an image forming apparatus 10 according to an embodiment, and FIG. 1A is a sectional view, and FIG. 1B is a model diagram.

FIG. 2 is a cross-sectional view illustrating a main configuration of the image forming apparatus 10 according to the embodiment.

FIG. 3 is a cross-sectional view illustrating a vicinity of a transfer roller of the image forming apparatus 10;

FIG. 4 is a front view showing a part of the image forming apparatus 10 of FIG.

FIG. 5 is a side view of FIG.

FIG. 6 shows a part of a conventional image forming apparatus 1, in which FIG. 6A is a sectional view and FIG. 6B is a model diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Image forming apparatus 12 Photoreceptor drum 16 Transfer roller 19 Recording paper 20 Flange 21 Drum shaft 22 First restricting member 23 Second restricting member 24 Urging member 25 Roller shaft 27 Frame 28, 29 Bearing 30 Slot 50 Restriction means A3 Photoconductor drum axis A4 Transfer roller axis

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichi Takeda 22-22, Nagaikecho, Abeno-ku, Osaka-shi, Osaka F-term (reference) 2H032 AA05 BA01 BA23 2H035 CA07 CB01 CD13 CZ00 2H071 DA09 DA15 EA04 EA06 EA14

Claims (4)

[Claims] An image carrier that carries a toner image; and a transfer roller that is urged toward the image carrier and that is arranged in a predetermined positional relationship with the image carrier by a regulating unit. In the image forming apparatus, the regulation unit may be spaced apart from an axial end of the image carrier and provided between an axis of the transfer roller and an axis of the image carrier. . 2. An image forming apparatus according to claim 1, wherein said regulating means is made of a material that absorbs impact. 3. The regulating means has a first regulating member provided to be loosely fitted on a shaft of an image carrier, and a second regulating member provided to be loosely fitted on a shaft of a transfer roller. 3. The image forming apparatus according to claim 1, wherein the first and second regulating members are in contact with each other. 4. The image forming apparatus according to claim 1, wherein said regulating means is provided at a position outwardly separated from an axial end of the transfer roller.