JPH05158387A - Image forming device - Google Patents

Abstract

PURPOSE:To prevent the vibration of an electrifying member side from being transmitted to an image carrier side, and simultaneously, a big electrifying noise from being made with a simple means when an electrifying member is brought into contact with an image carrier to electrify it. CONSTITUTION:In this image forming device electrifying the image carrier 1 in such a manner that the electrifying member 2 on which a voltage having an AC component is impressed, is brought into contact with the image carrier 1 whose inside is hallowed, a vibration absorbing member 20 for partitioning the image carrier 1, is provided in a prescribed location in the axial direction of the image carrier 1. When the voltage having the AC component is impressed on the electrifying member 2, it is vibrated, and tries to transmit the vibration to the image carrier 1. However, when the vibration absorbing member 20 is provided inside the image carrier 1, it is rigid, and the vibration is hardly transmitted. On the other hand, even if a columnar inside the image carrier 1 is vibrated, the vibration is damped by the vibration absorbing member 20 and the big electrifying noise is not made.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrostatic image forming apparatus such as an electrophotographic copying machine or a laser beam printer (LBP), and more particularly to an image forming apparatus in which an image carrier is charged by a contact type charging member. ..

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a corona charger utilizing corona discharge is widely used to uniformly charge a photosensitive drum which is an image carrier. Since a large amount of ozone is generated at the time of charging, a contact-type charging member that does not generate a large amount of ozone has been used in recent years.

FIG. 12 shows an image forming apparatus using this contact type charging member. That is, the charging roller 2 (charging member) made of a conductive member is brought into contact with the photosensitive drum 1 so as to be driven to rotate, and a predetermined voltage is applied to the charging roller 2, so that the charging roller 2 causes the photosensitive drum to move. It is uniformly charged. In this case, a bias voltage in which an AC voltage is superimposed on a DC voltage is applied to the charging roller 2 in order to make the charging uniform.

[0004]

However, while the charging roller 2 is in contact with the photosensitive drum 1, the charging roller 2
If a bias voltage having an AC component is applied to the charging roller 2, electric vibration is generated in the charging roller 2, and the charging roller 2 generates a charging sound that is a vibration sound. Then, the charging roller 2
The vibration of (1) is also transmitted to the photosensitive drum 1 side, causing the photosensitive drum 1 to resonate, increasing the charging sound, and causing blurring or unevenness in the image.

In particular, since most of the photosensitive drums 1 are composed of a hollow cylinder whose both ends are open, there is a disadvantage that they easily resonate, and if they resonate, the charging noise increases greatly.

In order to prevent the vibration of the photosensitive drum 1, it is possible to fill the photosensitive drum 1 with lead, rubber or the like to increase the weight of the photosensitive drum 1. However, in this way, the photosensitive drum 1 is provided. There is an inconvenience that the weight of the process cartridge 5 and the image forming apparatus main body 14 is increased, and it becomes difficult to move and carry the process cartridge 5 and the image forming apparatus main body 14.

The present invention has been made in view of the above problems, and an object of the present invention is to, when charging a charging member to contact an image carrier, charge the image carrier by a simple means. It is an object of the present invention to provide an image forming apparatus that can prevent the transmission to the image forming apparatus and does not generate a large charging noise.

[0008]

In order to achieve the above object, the present invention provides an image carrier by bringing a charging member to which a voltage having an AC component is applied into contact with an image carrier having a hollow interior. An image forming apparatus in which the body is charged is characterized in that a vibration absorbing member for partitioning the inside of the image carrier is provided at a predetermined position in the axial direction of the image carrier.

[0009]

When the charging member to which a voltage having an AC component is applied is brought into contact with the image carrier to charge the image carrier, the charging member vibrates to generate a charging sound. Then, the vibration of the charging member is also transmitted to the hollow image carrier, which causes image blurring and resonance of charging sound by the image carrier. It is considered that this resonance is caused by the vibration of the hollow image carrier causing the air column in the image carrier to vibrate in its axial direction.

Therefore, a vibration absorbing member for partitioning the image bearing member is provided at a predetermined position in the axial direction of the image bearing member to make the image bearing member as rigid as possible to make it difficult to transmit the vibration from the charging member, and The vibration of the air column is damped by this vibration absorbing member. In particular, if the vibration absorbing member is provided at the maximum amplitude position of the vibration wave of the air column (so-called antinode position of the vibration wave), the vibration wave damping effect of the vibration absorbing member is increased.

[0011]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

First, a first embodiment of the present invention will be described with reference to FIGS.
Will be described.

FIG. 5 shows a cross section of an image forming apparatus (copier). In FIG. 5, reference numeral 1 denotes a photosensitive drum (electrophotographic photosensitive member) as an image bearing member which is rotated in the arrow direction. Around the photosensitive drum 1, a charging roller 2 serving as a charging unit, a developing unit 3 serving as a developing unit, and a cleaning unit 4 serving as a cleaning unit are arranged, and these process devices are arranged inside the cartridge frame 5a together with the photosensitive drum 1. Is integrally stored in the apparatus main body 14 as the process cartridge 5.
It is removably arranged inside. This process cartridge 5 is intended to facilitate maintenance and the like by replacing the entire process cartridge 5 instead of replacing the individual device when the internal device reaches the end of its life.

A transfer charger 6 is disposed on the exposed side of the photosensitive drum 1 from the cartridge frame 5a, and a sheet feeding cassette 7 and a sheet feeding cassette 7 are provided on the sheet feeding side between the transfer charger 6 and the photosensitive drum 1. A paper roller 8, a registration roller 9, etc. are provided,
On the paper discharge side, a conveyance unit 10, a fixing device 11, a paper discharge roller 12,
A paper discharge tray 13 is arranged. Further, above the process cartridge 5, an image reading / exposing section including a lamp 14, a short focus lens 15 and the like is arranged.

That is, when the photosensitive drum 1 uniformly charged to a predetermined potential by the charging roller 2 is exposed to the image light L through the image reading and exposing section, an electrostatic latent image is formed on the photosensitive drum 1. It is formed. The electrostatic latent image is directed toward the developing device 3 as the photosensitive drum 1 rotates, and toner is supplied by the developing device 3 to be visualized as a toner image. The toner image is transferred to the photosensitive drum 1 via the transfer charger 6.
Of the photosensitive drum 1 which has been transferred onto the transfer material P from which the residual toner has been cleaned by the cleaning device 4, and is prepared for the next image formation.

On the other hand, the transfer material P in the paper feeding cassette 7 is taken out one by one by the paper feeding roller 8 and then sent to the registration roller 9, where the timing is adjusted by the registration roller 9 and the photosensitive drum 1 side. Is supplied to. Then, the transfer material P having the toner image transferred from the photosensitive drum 1 is sent to a fixing device 11, and the toner image is fixed as a permanent image by the fixing device 11, and then, via a paper discharge roller 12. The sheets are stacked on the discharge tray 13.

As shown in FIG. 6, the charging roller 2 is a charging member that is driven to rotate while being in contact with the photosensitive drum 1 to uniformly and primarily charge the outer surface of the photosensitive drum 1.
As shown by, the cored bar portion 2a of the rotating shaft made of a ferromagnetic material, and the charging part 2b formed concentrically around the cored bar portion 2a (conductive material such as high resistance rubber in which carbon is dispersed). (Formed from a member). When charging the charging roller 2, the core metal portion 2
A bias voltage in which an AC voltage is superimposed on a DC voltage is applied to a, and the charging roller 2 uniformly charges the photosensitive drum 1 to the same voltage as the DC component of the bias voltage. The AC component of the bias voltage has a function of uniformly charging the photosensitive drum 1 with the charging roller 2.

In the case of contact charging the photosensitive drum by the charging roller 2, an attractive force and a repulsive force alternately act between the surface of the charging roller 2 and the surface of the photosensitive drum 1 due to the AC component of the bias voltage. Vibration is generated in the charging roller 2. This vibration of the charging roller 2 causes the charging roller 2
Not only does it generate a vibrating noise (charging sound) with a high frequency to itself, but it is also transmitted to the photosensitive drum 1 side and vibrates the photosensitive drum 1 to cause image blurring and the like. Further, since the photosensitive drum 1 can be regarded as a hollow cylinder, the vibration of the photosensitive drum 1 causes the internal air column to vibrate, which resonates with the charging sound to further increase the charging sound. in this case,
As shown in FIG. 4, since the photosensitive drum 1 can be regarded as a cylinder whose both ends are open, the vibration wave (sound wave) W of the air column causes an antinode Wa having the largest amplitude A at both axial ends of the photosensitive drum 1. .. The antinode Wa of the vibration wave W is considered to be the place where the energy of the vibration wave W is the largest.

Therefore, in the present invention, a simple partition plate 20 is arranged at the position of the antinode Wa of the vibration wave W of the air column of the photosensitive drum 1.
By partitioning the inside of the photosensitive drum 1 at the predetermined axial position by the partition plate 20, the photosensitive drum 1 is made rigid so that the vibration of the charging roller 2 is hard to be transmitted to the photosensitive drum 1 side, and the partition plate 20 also serves as the photosensitive drum. The vibration wave W of the air column in No. 1 was attenuated to suppress the generation of resonance charging sound as small as possible.

That is, as shown in FIG. 1, the photosensitive drum 1
When a vibration wave for one wavelength is generated in the inner air column, for example, a vibration absorbing member made of rubber or the like having an outer diameter of 30.2 mm as shown in FIG. 2 is provided at both axial end portions and an intermediate portion of the photosensitive drum 1 having an inner diameter of 30 mm. The disk-shaped partition plate 20 made of is press-fitted and attached. By doing so, the photosensitive drum 1 becomes rigid and the vibration of the charging roller 2 is less likely to be transmitted, image blurring and the like can be reduced, and even if vibration of the air column occurs in the photosensitive drum 1, the antinode of the vibration wave W is generated. Since the partition plate 20 is located at the position Wa, the vibration wave W is attenuated and the resonance charging sound becomes small.
In this case, since the partition plate 20 may be thin, the weight of the photosensitive drum 1 does not increase so much, and there is no difficulty in carrying the process cartridge 5 or carrying the apparatus body 14.

The pattern of the vibration wave W generated in the air column in the photosensitive drum 1 is the frequency f of the vibration of the photosensitive drum 1.
Since various changes are caused by the vibration waves, vibration waves having various wavelengths as shown in FIG. 3 are generated in the air column in the photosensitive drum 1. For example, (a) in the figure shows a case where a vibration wave W of ½ wavelength (λ / 2) is generated in the air column in the photosensitive drum 1 having a constant length, and (b) in the figure shows one wavelength (λ). ), A vibration wave W of 3/2 wavelength (3λ / 2) is shown in (c), and a vibration wave W of 2 wavelength (2λ) is generated in (d). Shows. Therefore, when the partition plate 20 is put in the photosensitive drum 1, it is necessary to know the pattern of the vibration wave W generated in the air column in the photosensitive drum 1.

On the other hand, since the frequency of vibration of the photosensitive drum 1 can be calculated by design, the pattern of the vibration wave W generated in the air column inside the photosensitive drum 1 can be estimated in advance. Therefore, as shown in FIG. 3, the position of the antinode Wa of the vibration wave W at both ends in the axial direction of the photosensitive drum 1 as well as at the intermediate portion can be known from the pattern of the vibration wave W generated in the air column inside the photosensitive drum 1, The partition plate 20 can be placed here.

Here, if the axial length of the photosensitive drum 1, the speed of sound in the atmosphere, and the frequency f of the vibration wave W generated in the air column inside the photosensitive drum 1 are known, the wavelength λ of the vibration wave W can be known and The pattern of the vibration wave W generated in the air column in the drum 1 can be understood. Table 1 shows, for example, the axial length 3 of the photosensitive drum 1.
40 mm (a size capable of forming an image on the transfer material P having a maximum size of A3) and a sound velocity in the atmosphere of 340 m / s, the frequency f and the wavelength of the vibration wave W for each pattern of the vibration wave W in FIG. It shows ON.

[0024]

[Table 1] Next, a second embodiment of the present invention will be described with reference to FIGS. It should be noted that components having the same functions as those of the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In this embodiment, the partition plates 20 of various types are placed at the position of the antinode Wa of the vibration wave W generated in the air column in the photosensitive drum 1.
The case of providing will be described. For the sake of clarity, the pattern of the vibration wave W generated in the air column inside the photosensitive drum 1 is the same as that shown in FIG.

FIG. 7 shows an opening 20 at the center as shown in FIG.
It shows a case where a donut-shaped partition plate 20 (having a vibration absorbing member such as rubber) having a is attached to the photosensitive drum 1. In this way, the pressurization of the partition plate 20 does not generate an unnecessary pressurization state in the photosensitive drum 1. Also, FIG.
Shows a case where a groove 1a is formed on the inner peripheral surface of the photosensitive drum 1 and a partition plate 20 (composed of a vibration absorbing member such as rubber) is fitted into the groove 1a. Thus, the fixed position of the partition plate 20 can be set accurately. In this case, it goes without saying that the partition plate 20 may have the opening 20a at the center thereof. Further, when the partition plate 20 is made of a shape memory alloy and the partition plate 20 is mounted inside the photosensitive drum 1, the temperature is raised to a small diameter, and when the partition plate 20 is returned to room temperature, it is returned to the original diameter. The partition plate 20 may be pressed into the photosensitive drum 1.

Further, as shown in FIG. 10, the partition plate 20
May have a substantially triangular shape, and a slight gap C may be provided between the inner surface of the photosensitive drum 1 and the partition plate 20. In this way, the pressurization of the partition plate C does not generate an unnecessary pressurization state in the photosensitive drum 1. Further, as shown in FIG. 11, the photosensitive drum 1 and the partition plate 20 may be integrated. In this way, the number of parts can be reduced and the number of assembling steps can be reduced.

[0028]

As is apparent from the above description, according to the present invention, since the vibration absorbing member for partitioning the image carrier is provided at the axial position of the hollow image carrier, the image carrier becomes rigid and is separated from the charging member. This makes it difficult to transmit vibrations, and the vibration absorbing member can damp vibrations of the air column generated in the image carrier. Therefore, vibration is less likely to occur in the image carrier, image blurring and the like are reduced, and resonance of charging sound by the image carrier is also reduced.

[Brief description of drawings]

FIG. 1 is a side sectional view of a photosensitive drum and the like when three partition plates are attached inside the photosensitive drum of the image forming apparatus according to the first embodiment.

FIG. 2 is a perspective view of the partition plate.

FIG. 3 is a side cross-sectional view of the photosensitive drum and the like when a plurality of partition plates are attached to the photosensitive drum of the image forming apparatus in accordance with a vibration wave pattern.

FIG. 4 is an explanatory diagram of a vibration wave generated in a photosensitive drum of the image forming apparatus.

FIG. 5 is a side sectional view of the image forming apparatus.

FIG. 6 is a perspective view showing a photosensitive drum and a charging roller of the image forming apparatus.

FIG. 7 is a side cross-sectional view of the photosensitive drum and the like when the first partition plate is attached inside the photosensitive drum of the image forming apparatus according to the second embodiment.

FIG. 8 is a perspective view of the partition plate.

FIG. 9 is a side sectional view of the photosensitive drum and the like when a second partition plate is attached inside the photosensitive drum.

FIG. 10 is a front cross-sectional view of the photosensitive drum and the like when a third partition plate is attached inside the photosensitive drum.

FIG. 11 is a side sectional view of a photosensitive drum or the like when a partition plate is integrally provided in the photosensitive drum.

FIG. 12 is a diagram for explaining a conventional technique.

[Explanation of symbols]

 1 photosensitive drum (image carrier) 2 charging roller (charging member) 20 partition plate (vibration absorbing member) W vibration wave

Claims (2)

[Claims] 1. An image carrier in which an image carrier is charged by bringing a charging member, to which a voltage having an AC component is applied, into contact with an image carrier having a hollow interior. An image forming apparatus, wherein a vibration absorbing member for partitioning the inside of the image carrier is provided at a predetermined position in the axial direction of the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the vibration absorbing member is provided at a maximum amplitude position of a vibration wave generated in the image carrier by the vibration of the charging member.