JPH08211817A - Image forming device - Google Patents

Abstract

PURPOSE: To provide high quality images and to increase speeds by providing an elastic member at least either between the flange shaft of an image carrier end portion and a bearing supporting this or between the shaft of a charging member and a bearing supporting this. CONSTITUTION: The bearing 5 of a flange shaft 4 for rotary-driving an image carrier 1, the bearing 7 of a shaft 6 made of an electrically conductive material for loading a charging roller 2 and a contact portion 8 with the frame body of a cartridge provided with the frame body for supporting the image carrier 1 and the charging roller 2 and a cleaner 3 are constructed by elastic materials. Thus, vibrations produced when an AC voltage is impressed as a charging bias via the shaft 6 and noises due to the vibrations are reduced as many as possible. Because of reduced vibrations and noises, enlargement of the driving sections and other members due to deterioration in image quality and the increased weight of the image carrier caused by charging differences because of reduction in the frequency of the charging bias is eliminated.

Description

Detailed Description of the Invention

[0001]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrostatic transfer process such as an electrostatic copying machine and a printer.

[0002]

2. Description of the Related Art The known image forming apparatus as described above includes a step of charging a photoconductive layer on the surface of an image carrier having a photoconductive layer formed on the surface of a conductive cylindrical body by a charging means. are doing.

Conventionally, a corona discharger has been often used as a charging means, but recently, a means such as a charging roller or a charging blade which comes into direct contact with an image bearing member requires a low applied voltage, and ozone. As is well known, it is becoming more and more popular due to advantages such as low occurrence of

In this type of contact-type charging means, an AC voltage is applied as a charging bias in order to evenly charge the photoconductive layer on the surface of the image bearing member. For this reason, it is inevitable that the charging member and the image carrier vibrate at the time of applying the bias, and noise is generated by hitting each other.

In order to avoid such a problem, hitherto, measures have been taken to reduce the frequency of the charging bias. At the same time, however, such means tend to cause uneven charging, and there is a limit to speeding up the image forming apparatus. Further, when the image signal is a digital signal, for example, when the number of input pixels is increased to improve the image quality in a laser beam printer or the like, there is a problem that the influence of charging unevenness due to the frequency decrease becomes remarkable.

Further, in order to avoid noise, it has also been proposed that a rigid body is usually enclosed inside a hollow cylindrical image carrier to increase its weight and reduce vibration noise.

At the same time, however, the filling of the image carrier with such an image carrier causes an increase in the weight of the driving system, an increase in the cost of the compound, and a decrease in the productivity. There is a problem that post-treatment such as recycling becomes difficult because the material such as aluminum cannot be treated as a single component.

The present invention has been made to cope with such a situation, and enables an image carrier capable of effectively preventing noise generated during charging, and high image quality and high speed using the image carrier. It is an object of the present invention to provide such an image forming apparatus.

[0009]

Configuration of the Invention

In order to achieve the above-mentioned object, the present invention comprises an image carrier and a contact type charging member which is disposed in contact with the image carrier, and these are mounted on a cartridge outer frame. In the cartridge for the image forming apparatus covered by the above, at least one of the image bearing member end flange shaft and the bearing supporting the shaft and the shaft of the charging member and the bearing supporting the shaft are elastic. An image forming apparatus cartridge (1) in which materials are arranged, or an image carrier, a contact-type charging member arranged in contact with the image carrier, and a cleaning unit are provided, and these are provided in a cartridge outer frame. In a covered cartridge for an image forming apparatus, an elastic member is provided at a contact portion between a cartridge outer frame of a container of a cleaning unit and a cartridge frame supporting an image carrier and a charging member. The ridge (2) or the cartridge (3) of the above (1) or (2), wherein the charging member is a charging roller, or the cartridge (3) of the above (1) or (2) An image forming apparatus cartridge (4), the member of which is a charging blade, or an image forming apparatus (5) including the cartridge described in (1) or (2) above.

With such a structure, it is possible to significantly reduce the charge unevenness due to the vibration and noise generated by the application of the charging bias at a low cost, and the vibration propagates to the cartridge or each part of the image forming apparatus to improve the image quality. Deterioration can be prevented.

[0011]

DESCRIPTION OF THE PREFERRED EMBODIMENTS "FIG. 1" is a schematic side sectional view of an essential part of a process cartridge detachably mountable to an image forming apparatus, showing an embodiment of the present invention. A charging roller 2 is disposed in contact with a cylindrical image carrier 1. Reference numeral 3 is a cleaning blade attached to the cleaning device for removing residual toner.

Further, reference numeral 4 is a flange shaft for rotationally driving the image bearing member, which is received by the bearing 5. Reference numeral 6 designates a shaft made of a conductive material on which the charging roller 2 is mounted, through which a charging bias is applied by a power source (not shown). Reference numeral 7 is a bearing that shafts the shaft 4. Further, reference numeral 8 indicates a contact portion between the frame supporting the image carrier 1 and the charging roller 2, the cleaning device, and the cartridge frame.

In such a device, the bearings 5, 6 and the frame 8 are made of an elastic material. In this case, since relative rotation is involved between the shaft 4 and the bearing 5 and between the shaft 6 and the bearing 7, and lubricity and wear resistance are required, a thin metal layer is formed on the surface of the elastic material. Alternatively, it is preferable to use a fluororesin material.

As the elastic material, synthetic rubber such as urethane rubber, chloroprene rubber, silicone rubber, propylene rubber, styrene-butadiene rubber, etc. are preferable in consideration of their effectiveness in vibration and sound proofing.

As the substrate of the image bearing member, metal, particularly aluminum, is preferable in consideration of moldability and workability. As the photoconductive layer on the surface of the image bearing member, a conventionally known photoconductive layer may be formed into a film by an appropriate means. However, when the contact charging member is used, the organic photoconductive layer is suitable.

For drive transmission of the formed image carrier end portion,
The material of the flange used for bearings is moldability,
From the viewpoint of workability, slidability, durability, etc., aluminum,
Polycarbonate and the like can be preferably used.

As a charging member, it is needless to say that a charging blade other than the illustrated charging roller can be used.
As the material, an elastic material such as rubber in which carbon, metal powder, or the like is dispersed to adjust the volume resistivity appropriately can be used.

The bias voltage applied to the charging roller is
An oscillating voltage in which a voltage value is periodically changed with time, which is formed by superimposing an AC voltage on a DC voltage, is suitable. For example, as disclosed in JP-A-63-149668,
It is preferable that the peak-to-peak voltage is at least twice the charging start voltage of the image carrier when only the DC voltage is applied.

The waveform of the applied voltage is not limited to a sine wave, and a rectangular wave, a triangular wave, a sawtooth wave, a pulse wave generated by turning on / off a DC power source, or the like can be used as appropriate. A sinusoid containing no waves is preferred.

Examples of the present invention will be described below.

Example 1 An aluminum cylinder having a diameter of 30 mm, a length of 254 mm and a wall thickness of 0.75 mm was prepared as a substrate of an image bearing member, and a photosensitive layer having the following composition was formed on the surface thereof. (1) Conductive coating layer The main constituent is a powder of tin oxide and titanium oxide dispersed in a phenol resin. Film thickness 1
8μ (2) Undercoat layer Mainly composed of modified nylon and copolymerized nylon. Thickness 1.0 μ (3) Charge generation layer Mainly composed of a disazo pigment having an absorption band in the long wavelength region dispersed in an acrylic resin.
Film thickness: 0.2 μ (4) Charge transport layer Mainly composed of a hydrazone compound having hole transportability dissolved in a polycarbonate resin. Film thickness: 25 μ The image carrier thus constructed was incorporated into a cartridge of an image forming apparatus, and a urethane rubber having a thickness of 1.5 mm was attached to the shaft of the image carrier flange and the bearing of the frame on the cartridge side at this time. .

The contact surface between the urethane rubber and the image bearing flange was coated with a fluororesin (polytetrafluoropolyethylene).

This cartridge was mounted on a laser beam printer, and the charging noise when a charging bias was applied to the charging roller was measured. At this time, the process speed of the device is 47 mm / sec, the DC voltage is -650 V, and the frequency is 470.
An oscillating voltage with a peak-to-peak voltage of 2000 V was applied by superimposing an AC voltage of Hz.

The sound is measured by installing the above device in an anechoic chamber with a background noise of 30 db (A), and placing a sound level meter [50 cm on the front surface of the image carrier (direction orthogonal to the axis of the image carrier)]. NL-02 ”(manufactured by Rion Co., Ltd.) was placed. The printer is modified so that it can drive only the image carrier and does not generate operating noise from other parts.

Under these conditions, the sound pressure Xdb (A) when the image carrier is not driven and the sound pressure Ydb when the image carrier is driven.
(A) was measured, and the difference Δ = Y−Xdb (A) was taken as the noise generated by charging.

[Example 2] The measurement was performed in the same manner as in [Example 1] except that the bearing member of the flange shaft of the image bearing member was made of urethane rubber.

[Comparative Example 1] In [Example 1], the measurement was performed under the same conditions as in [Example 1] except that the urethane rubber bearing was not used in the flange portion of the image carrier.

[Embodiment 3] An image carrier similar to that of [Embodiment 1] was assembled in a cartridge, and an iron ring was attached to the contact surface between the shaft of the charging roller and the urethane rubber bearing. At this time, the bearing portion of the cartridge was slightly ground so that the shaft of the charging roller could be easily mounted. Such a cartridge was mounted on a laser beam printer, and the results were measured in the same manner as above.

Example 4 The measurement was performed in the same manner except that the urethane rubber used in [Example 3] was silicon rubber.

[Embodiment 5] An image carrier similar to that in [Embodiment 1] is incorporated in a cartridge, and a frame body for supporting the image carrier and the charging roller of the cartridge, a cleaning container and a cartridge outer frame. Urethane rubber was attached to the contact area of.
With such a cartridge, the sound was measured in the same manner as in [Example 1].

[Embodiment 6] Except that silicone rubber is attached to the contact portions of the cleaning container and the outer frame of the cartridge in [Embodiment 5],
The measurement was performed in the same manner as above.

[Example 7] The image carrier used in [Example 1], the charging roller used in [Example 3], and the cartridge used in [Example 5] were used. ] Was measured under the same conditions.

The results of the above experiments are shown in the chart of FIG. Considering the above results, the increase Δ of the sound pressure is 4 db.
In the following cases, it was confirmed that the operation as an image forming apparatus can be performed at a stable sound range level without any problem in terms of hearing and function of the apparatus in practical use.

[0034]

As described above, according to the present invention,
An elastic material is mounted as a cushioning material or a bearing on the flange portion of the image carrier, the connection part of the charging member, the frame part supporting the image carrier and / or the charging member, the cleaning part, and the contact part with the outer frame of the cartridge. As a result, it is possible to suppress as much as possible the vibration that occurs when an AC voltage is applied as the charging bias and the noise that results from this.

Thus, in order to suppress vibration and noise,
It is not necessary to reduce the image quality due to uneven charging due to the reduction of the frequency of the charging bias, and to increase the weight of the image carrier to increase the size of the driving unit and other members. In addition, by suppressing the vibration at the charging portion, the operation of the cartridge and the image forming apparatus including the cartridge can be stabilized, which largely contributes to obtaining a high quality image.

[Brief description of drawings]

FIG. 1 is a schematic side sectional view of a main part of an image forming apparatus cartridge showing an embodiment of the present invention.

FIG. 2 is a chart showing the experimental results of the example of the present invention and the comparative example device.

[Explanation of symbols]

 1 image carrier 2 charging roller 3 cleaning blade 4 flange shaft of image carrier 5 bearing 6 shaft of charging roller 7 bearing 8 frame

Claims (5)

[Claims] 1. A cartridge for an image forming apparatus, comprising: an image carrier; and a contact-type charging member disposed in contact with the image carrier, the cartridge being covered with an outer frame of the cartridge, wherein the image carrier end flange. A cartridge for an image forming apparatus, in which an elastic material is provided at least on one side between a shaft and a bearing supporting the shaft and between a shaft of the charging member and a bearing supporting the shaft. 2. A cartridge for an image forming apparatus comprising an image carrier, a contact-type charging member disposed in contact with the image carrier, and a cleaning unit, the cartridge being used for an image forming apparatus, the cleaning unit comprising: An image forming apparatus cartridge in which an elastic material is provided at a contact portion between a cartridge outer frame of a container and a cartridge frame that supports an image carrier and a charging member. 3. The charging device according to claim 1, wherein the charging member is a charging roller.
Alternatively, the image forming apparatus cartridge according to claim 2. 4. A cartridge for an image forming apparatus according to claim 1, wherein the charging member is a charging blade. 5. "Claim 1" and / or "Claim 2"
An image forming apparatus comprising the cartridge as described.