JPH08123194A - Image forming device - Google Patents

Abstract

PURPOSE: To provide an image forming device capable of always keeping the gap between a developer carrier and an image carrier constant and reducing the maintenance cost. CONSTITUTION: A developing unit is arranged in contact with a photoreceptor drum 1 on which an electrostatic latent image is formed, in the parts of the developing sleeve 6d and gap rollers 6b of the developing unit and the gap (d) between the developing sleeve 6d and the drum 1 is kept constant Toner housed in the developing unit is supplied from the developing sleeve 6d to the drum 1 and the electrostatic latent image formed on the drum 1 is visualized with the toner. Since the gap rollers 6b are made of a material having hardness higher than that in the contact part of the drum 1 with the gap rollers 6b, they are not worn by the drum 1 exchanged at prescribed cumulative working time intervals. Thus, the gap between the drum 1 and the developing sleeve 6d is always kept constant, a developer is stably supplied and a high quality 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 image forming apparatus such as a copying machine.

[0002]

2. Description of the Related Art In a full-color copying machine, a photosensitive drum made of metal such as Al is used as an image bearing member on which an electrostatic latent image is formed, and a yellow electrostatic latent image is formed on the photosensitive drum.
A developing roller is provided as a developer bearing member of a developing device that supplies magenta and cyan developers to visualize an electrostatic latent image. To this developing roller, resin gap rollers that rotate in contact with the photosensitive drum are fixed at both ends in the axial direction perpendicular to the rotation direction of the photosensitive drum. The radius of these gap rollers is It is set larger than the radius.

Then, the developers of the respective colors carried by the developing rollers are sequentially supplied to the electrostatic latent images on the photosensitive drums, and the developers of the respective colors are superposed to develop the colors of the electrostatic latent images. Be done. As described above, in the full-color copying machine, since the developers of the respective colors are supplied to the same electrostatic latent image a plurality of times, the developing roller maintains a constant gap with respect to the photosensitive drum. It is necessary to carry out development in order to avoid color mixture and prevent toner scattering and carrier drop.

Even in a monochrome copying machine, when the gap between the developing roller and the photosensitive drum changes, toner scattering and carrier drop occur, and the quality of the formed image deteriorates.

Therefore, in this type of image forming apparatus, as described above, the radius of the developing roller is set to be smaller than the radius of the gap roller, and a predetermined distance is provided between the developing roller and the photosensitive drum. A gap is formed.

[0006]

In the above-mentioned conventional image forming apparatus, the gap roller is made of resin and has a hardness lower than that of the metal photosensitive drum, and the contact rotation speed of the gap roller is lower than that of the photosensitive drum. However, the gap roller wears over time, the gap between the developing roller and the photosensitive drum changes, and in a full-color copying machine, color mixing occurs and the quality of the formed image deteriorates. Become.

On the other hand, in Japanese Unexamined Patent Publication No. 5-119602, the hardness of the contact portion of the photosensitive drum with the gap roller and the hardness of the gap roller are made the same, and the gap between the developing roller and the photosensitive drum is set. There has been proposed an electrophotographic apparatus that keeps the temperature constant over time.

However, recent image forming apparatuses are required to operate at a high speed, the number of images formed in a unit time increases dramatically, and the photosensitive drum is electrostatically fatigued rather than worn out with respect to the photosensitive drum. However, in order to prevent the quality of the formed image from deteriorating, maintenance is usually taken to regularly replace the photosensitive drum. For such maintenance, it is desirable that the gap roller is not replaced at the time of replacement of the photoconductor drum and can be used up to the limit of the life of the device because the maintenance cost of the device is reduced.

The present invention has been made in view of the current state of the maintenance work of the image forming apparatus as described above, and the gap between the developer bearing member and the image bearing member is always kept constant to reduce the maintenance cost. Another object of the present invention is to provide an image forming apparatus capable of performing the above.

[0010]

In order to achieve the above object, the invention according to claim 1 is an image carrier on which an electrostatic latent image is formed, and the electrostatic latent image is supplied to the image carrier. A developer carrier that contains a developer that forms a visible image corresponding to the image;
It is provided on the developer carrying member and comes into contact with the image carrying member,
In an image forming apparatus having a contact member that keeps a gap between the developer carrier and the image carrier constant, the contact member is higher in hardness than a contact portion of the image carrier with the contact member. It is characterized by being formed of a material having hardness.

Similarly, in order to achieve the above object, the invention according to claim 2 corresponds to the electrostatic latent image, and an image carrier on which an electrostatic latent image is formed, and the electrostatic latent image supplied to the image carrier. A developer carrier that contains a developer that forms a visible image, and a developer carrier that is provided on the developer carrier and comes into contact with the image carrier so that the gap between the developer carrier and the image carrier is constant. In an image forming apparatus having a contact member for holding the contact member,
It is characterized in that the inner ring is a radial rolling bearing formed of an insulating material.

[0012] Similarly, in order to achieve the above object, the invention according to claim 3 corresponds to the electrostatic latent image, and an image carrier on which an electrostatic latent image is formed, and the electrostatic latent image supplied to the image carrier. A developer carrier that contains a developer that forms a visible image, and a developer carrier that is provided on the developer carrier and comes into contact with the image carrier so that the gap between the developer carrier and the image carrier is constant. In an image forming apparatus having a contact member for holding the contact member,
The rolling element is a radial rolling bearing formed of an insulating material.

[0013]

According to the first aspect of the invention, the developer carrier is disposed in contact with the image carrier on which the electrostatic latent image is formed at the contact member portion, and the developer carrier and the image carrier are connected. The gap is kept constant. Then, the developer carried on the developer carrier is supplied to the image carrier, and the electrostatic latent image formed on the image carrier is visualized by the developer. In this case, since the contact member is formed of a material having a hardness higher than the hardness of the contact portion of the image carrier with the contact member, the contact member contacts the image carrier replaced every predetermined cumulative operating time. Does not wear, the gap between the developer bearing member and the image bearing member is kept constant, and a stable supply of the developer is performed.

According to the second aspect of the present invention, the developer bearing member is disposed in contact with the image bearing member on which the electrostatic latent image is formed at the contact member portion, and the developer bearing member and the image bearing member are connected. The gap is kept constant. Then, the developer carried on the developer carrier is supplied to the image carrier, and the electrostatic latent image formed on the image carrier is visualized by the developer. in this case,
Since the contact member is a radial rolling bearing whose inner ring is made of an insulating material, the contact member does not wear with respect to the image carrier that is replaced every predetermined cumulative operating time, and the developer carrier and the image carrier are not worn. The gap with the body is kept constant, the developer is stably supplied, and the operation of applying the developing bias to the developer carrier is also performed.

According to the third aspect of the present invention, the developer carrying member is disposed in contact with the image carrying member on which the electrostatic latent image is formed at the contact member portion, and the developer carrying member and the image carrying member are provided. The gap is kept constant. Then, the developer carried on the developer carrier is supplied to the image carrier, and the electrostatic latent image formed on the image carrier is visualized by the developer. in this case,
Since the contact member is a radial rolling bearing in which the rolling element is formed of an insulating material, the contact member does not wear against the image carrier replaced every predetermined cumulative operating time, and the developer carrier and the image carrier are not worn. The gap with the body is kept constant, the developer is stably supplied, and the operation of applying the developing bias to the developer carrier is also performed.

[0016]

【Example】

[First Embodiment] First, the first embodiment of the present invention will be described with reference to FIG.
Or, it demonstrates with reference to FIG. FIG. 1 is an explanatory diagram showing a configuration of a main portion of the present embodiment, FIG. 2 is an explanatory diagram showing an overall configuration of the present embodiment, and FIG. 3 is an explanatory diagram showing a configuration of a main portion of a modified example of the present embodiment. .

In FIG. 2, reference numeral 1 denotes a photosensitive drum on which a latent image is formed. The charger 2 for charging the photosensitive drum 1 with respect to the peripheral surface 1a of the photosensitive drum 1 and the residual of the photosensitive drum 1 are left. A discharging lamp 5 for discharging the electric potential, a cleaning device 8 for removing the residual toner on the photosensitive drum 1 by a cleaning blade 8a, a transfer device 7 for transferring the toner image of the photosensitive drum 1 on a transfer paper, and a discharging device for the photosensitive drum 1. A pre-transfer exposure device 3 for irradiating light for use and a developing device 6 for supplying toner to the latent image on the photosensitive drum 1 to form a toner image are arranged counterclockwise in this order.

Then, the photosensitive drum 1 is rotated in the clockwise direction, and an original image is exposed on the photosensitive drum 1 by the exposure device 9 between the charging device 2 and the developing device 6.
Between the pre-transfer exposure device 3 and the transfer device 7, the transfer paper P is supplied to the photosensitive drum 1 by the registration roller 13 and the pressure roller 14.

In this embodiment, as shown in FIG.
The developing device 6 is provided with a developing sleeve 6d, and gap rollers 6b are fixed to both ends of the developing sleeve 6d at right angles to the rotation direction of the photosensitive drum 1, and the radius of the gap roller 6b is the radius of the developing sleeve 6d. The developing sleeve 6d and the peripheral surface 1a of the photosensitive drum 1 are set larger than
A development gap d is set between them.

Although not shown, the developing device 6 is provided with a paddle roller and a toner concentration sensor, and the toner agitated by the paddle roller is transferred from the developing sleeve 6d to the photosensitive drum 1.
The toner is supplied from the toner hopper to the developing device 6 based on the detection value of the toner density sensor. In this embodiment, the gap roller 6
b is formed of a material having a hardness higher than that of the material of the photoconductor drum 1 that contacts the gap roller 6b.

The operation of this embodiment having such a configuration will be described. After the transfer, the residual toner on the photosensitive drum 1 is removed by the cleaning blade 8a of the cleaning device 8 and the residual potential of the photosensitive drum 1 is removed by the static elimination lamp 5, and then the photosensitive drum 1 is uniformly charged by the charger 2. Be charged to. Then, the exposure device 9 exposes the original image to the photosensitive drum 1 that has reached the position of the exposure device 9, and a latent image of the original image is formed on the photosensitive drum 1.

When the latent image position of the photoconductor drum 1 reaches the position of the developing device 6, a predetermined gap d is formed between the photoconductor drum 1 and the photoconductor drum 1 by a gap roller 6b which rotates in contact with the photoconductor drum 1.
The toner is supplied to the photosensitive drum 1 by the developing sleeve 6b which holds and rotates, and a toner image corresponding to the latent image is formed on the photosensitive drum 1. This toner image is
The registration roller 13 and the pressure roller 14 transfer the image onto the transfer paper P supplied so as to be in contact with the photosensitive drum 1, and the image formation on the transfer paper is completed.

In this embodiment, the hardness of the material of the gap roller 6b is set higher than the hardness of the photoconductor drum 1 which is in contact with the gap roller 6b, so that it is not worn by the developing operation. Then, with respect to the photosensitive drum 1 that is regularly replaced due to its electrostatic life, the developing sleeve 6d is always operated with a predetermined gap d, and stable developing operation without toner scattering and carrier drop is performed. Let me do it
High quality imaging is performed until the device reaches its operational life.

As described above, according to this embodiment, the hardness of the material of the gap roller 6b is set to be higher than the hardness of the photosensitive drum 1 which is in contact with the gap roller 6b.
Even when the photoconductor drum 1 is replaced due to its electrostatic life, the photoconductor drum 1 is continuously used as it is, and the new photoconductor drum 1 is used.
On the other hand, it is possible to always operate the developing sleeve 6d while maintaining a predetermined gap to continue the high quality image forming operation and reduce the maintenance cost.

FIG. 3 shows a modified example of this embodiment, in which both ends of the photosensitive drum 1 are formed of resin flanges 1d, and the gap rollers 6b are brought into contact with the flanges 1d. Also in this case, the hardness of the material of the gap roller 6b is set higher than that of the flange 1d. In the case of FIG. 3 as well, the same operation as in the case of FIG. 2 already described is performed and the same effect is obtained.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. FIG. 4 is an explanatory diagram showing the configuration of the main part of this embodiment.

In the present embodiment, as shown in the figure, the gap rollers 6c of the first embodiment are replaced at both ends of the developing sleeve 6d in the axial direction perpendicular to the rotation direction of the photosensitive drum 1.
A radial rolling bearing 6c, in which a rolling element 20b is arranged, is fixed between the inner ring 20a and the outer ring 20c. The radial rolling bearing 6c has a structure in which the inner ring 20a is made of resin, ceramic,
It is made of an insulating material such as glass. The outer ring 20c and the rolling element 20b of the radial rolling bearing 6c are formed of high carbon chromium bearing steel or stainless steel defined by JIS. The configuration of the other parts of this embodiment is the same as that of the first embodiment already described, and therefore a duplicate description will not be given.

In this embodiment, the same developing operation as that of the first embodiment described above is performed, and since the inner ring 20a is made of an insulating material, the developing sleeve 6d and the photosensitive drum 1 are insulated from each other. Then, the developing bias can be applied to the developing sleeve 6d to perform the developing operation.

As described above, according to this embodiment, in addition to the effects obtained in the first embodiment described above, the inner ring 20
Since a is formed of an insulating material, the developing sleeve 6d and the photosensitive drum 1 are insulated from each other, and the developing sleeve 6d
It is possible to apply a developing bias to the developing device and apply the developing bias as it is to a device of the type.

As a modification of this embodiment, the rolling element 2
It is also possible to form 0b with an insulator such as resin, ceramic, or glass, and to form the outer ring 20c and the inner ring 20a with high carbon chrome bearing steel or stainless steel specified in JIS. Even in this case, the same operation as this embodiment is performed, and the same effect as this embodiment can be obtained.

In each of the embodiments, the monochrome copying machine is taken up for description, but the present invention is not limited to each embodiment. For example, a plurality of developing sleeves are provided and the photosensitive drum is formed. The present invention can also be applied to a full-color copying machine that forms a color image by supplying toners of yellow, magenta, and cyan colors to the latent image.

[0032]

According to the first aspect of the present invention, the contact member that contacts the image bearing member to maintain a constant gap between the developer bearing member and the image bearing member contacts the contact member of the image bearing member. Since it is made of a material with a hardness higher than the hardness of the part,
For the image carrier that is replaced every predetermined cumulative operating time,
The contact member of the developer carrying member is not worn and the gap between the developer carrying member and the image carrying member is always kept constant, so that the latent image is always supplied with a stable developer and a high quality image is obtained. And the maintenance cost can be reduced. According to the invention described in claim 2, in addition to the effect obtained by the invention described in claim 1, a contact member that contacts the image carrier and holds the gap between the developer carrier and the image carrier constant is provided. Since the inner ring is a radial rolling bearing formed of an insulating material, the dimensional accuracy and rotation accuracy are high, the gap between the developer carrier and the image carrier can be maintained with higher accuracy, and the developing sleeve The present invention can be applied to an image forming apparatus that applies a developing bias. According to the invention of claim 3, in addition to the effect obtained by the invention of claim 1, a contact member for contacting with the image carrier to hold a constant gap between the developer carrier and the image carrier is provided. Since the rolling element is a radial rolling bearing formed of an insulating material, the dimensional accuracy and the rotation accuracy are high, and the gap between the developer carrier and the image carrier can be maintained with higher accuracy, and the developing sleeve The present invention can also be applied to an image forming apparatus that applies a developing bias to the image forming apparatus.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a main part of a first embodiment of the present invention.

FIG. 2 is an explanatory diagram showing an overall configuration of the same embodiment.

FIG. 3 is an explanatory diagram showing a configuration of a main part of a modified example of the same embodiment.

FIG. 4 is an explanatory diagram showing a configuration of a main part of a second embodiment of the present invention.

[Explanation of symbols]

 1 photoconductor drum 1d flange part 6 developing device 6a gap roller 6c radial rolling bearing 6d developing sleeve 7 transfer device 8 cleaning device 9 exposing device 20a inner ring 20b rolling element 20c outer ring

Claims (3)

[Claims] 1. An image bearing member on which an electrostatic latent image is formed, and a developer bearing member containing a developer which is supplied to the image bearing member and forms a visible image corresponding to the electrostatic latent image. Provided on the developer bearing member and in contact with the image bearing member,
In an image forming apparatus having a contact member that keeps a gap between the developer carrier and the image carrier constant, the contact member is higher in hardness than a contact portion of the image carrier with the contact member. An image forming apparatus characterized by being formed of a material having hardness. 2. An image bearing member on which an electrostatic latent image is formed, and a developer bearing member containing a developer which is supplied to the image bearing member and forms a visible image corresponding to the electrostatic latent image. Provided on the developer bearing member and in contact with the image bearing member,
In an image forming apparatus having a contact member that maintains a constant gap between the developer bearing member and the image bearing member, the contact member is a radial rolling bearing having an inner ring made of an insulating material. Image forming apparatus. 3. An image bearing member on which an electrostatic latent image is formed, and a developer bearing member containing a developer which is supplied to the image bearing member and forms a visible image corresponding to the electrostatic latent image. Provided on the developer bearing member and in contact with the image bearing member,
In an image forming apparatus having a contact member that keeps a gap between the developer carrier and the image carrier constant, the contact member is a radial rolling bearing in which the rolling element is made of an insulating material. Image forming apparatus.