JP3517451B2 - Process cartridge and image forming apparatus - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge and an image forming apparatus for forming an image using a developer.

[0002]

2. Description of the Related Art An image forming apparatus such as a printer forms a latent image by selectively exposing a photoconductor uniformly charged by a charging device to form a latent image by a developing device. At the same time, the image formed by the developer is transferred to a recording medium to record an image. In such a device, the maintenance of each member was performed by a professional service person.

Therefore, the photosensitive member, the charging device, the developing device, the cleaning portion and the like are integrally formed into a cartridge so that the user can load the cartridge into the main body of the apparatus to replenish the developer and extend the service life. It has been put into practical use that the parts of the photoconductor that have reached can be replaced and the maintenance is easy.

In such a process cartridge, it is necessary to apply a bias voltage to each of the charging roller forming the charging device and the developing roller forming the developing device, and to electrically ground the photosensitive member. In order to rotate such a charging roller and a developing roller, a contact member is brought into contact with the rotating body, and the main assembly of the apparatus and the rotating body are electrically connected via the electric contact.

[0005]

However, since the electric contact member has conventionally been made of a metal member having excellent conductivity, when the rotating member rotates during image formation, the metal members rub against each other at the contact portion. However, there was a problem that abnormal noises and abnormal noises occurred.

Therefore, in order to prevent the occurrence of the abnormal noise and the abnormal noise, the conductive grease is applied to the rubbing portions of the metals, but the grease applying work is performed manually by the surroundings. Therefore, there is a problem in that workability is poor because it is necessary to pay attention so as not to adhere to the member, and it is difficult to cope with automation of the production line to improve productivity.

The present invention is to solve the above-mentioned conventional problems, and an object of the present invention is to maintain good conductivity and to prevent the generation of abnormal noise or noise without applying grease or the like. An object of the present invention is to provide a process cartridge and an image forming apparatus having a contact member that can be prevented.

[0008]

A typical structure according to the present invention for achieving the above object is a process cartridge detachable from an image forming apparatus main body, which includes a photosensitive drum and a conductive cored bar. A charging roller for charging the photosensitive drum and a power supply terminal provided on the apparatus main body when the process cartridge is mounted on the apparatus main body, and for applying the charging roller to the charging roller. A power receiving terminal for receiving a bias voltage from the device body,
An electrode electrically connected to the power receiving terminal, the core metal and the electrode for supplying the bias voltage to the core metal
An electric contact member interposed between the electrode and the sliding contact with the electrode.
The portion having a protrusion, an electrical contact member made of a conductive resin member in which a conductive material is filled in a resin material made of polyphenylene sulfide , and the power receiving terminal,
The bias voltage is applied to the charging roller via an electrode, an electrical contact member made of a conductive resin member, and a cored bar.

[0009]

In the above structure, since the electric contact member having the projection is made of the conductive resin member, even if the contact member rubs against another metal contact without impairing the conductive performance. No abnormal noise or noise is generated.

Therefore, since it is not necessary to apply grease or the like as in the conventional case, it becomes easy to automate the production line.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a process cartridge and an image forming apparatus according to the present invention will be specifically described with reference to the drawings.

First Embodiment A first embodiment will be described with reference to FIGS. 1 to 8.
1 is a structural explanatory view of the image forming apparatus in which the process cartridge is mounted, FIG. 2 is a structural explanatory view of the process cartridge, FIG. 3 is an explanatory drawing of the cartridge mounting structure, and FIGS. It is a structure explanatory view of an electric contact member for applying a charging bias to a charging roller.

Here, as the order of the description, the overall structure of the image forming apparatus and the process cartridge will be described first, and then the structure of the electrical contact member will be described.

[Overall Structure] As shown in FIG. 1, this image forming apparatus A irradiates a laser beam L based on image information from an optical system 1 to a developer (hereinafter referred to as “photosensitive member”) on a photosensitive drum which is a photosensitive member. Image referred to as "toner". Then, in synchronization with the formation of the toner image,
The recording medium 2 is conveyed from the paper feed cassette 3a by the conveying means 3 including a pickup roller 3b, a pair of registration rollers 3c, and the like, and in the image forming portion cartridged as the process cartridge B, the toner image formed on the photosensitive drum is formed. Is transferred to the recording medium 2 by applying a voltage to the transfer roller 4 as a transfer unit, and the recording medium 2 is guided by the guide plate 3d and conveyed to the fixing unit 5.

The fixing means 5 comprises a driving roller 5a and a fixing roller 5b containing a heater, and applies heat and pressure to the recording medium 2 passing therethrough to fix the transferred toner image. Then, the recording medium 2 is conveyed by the discharge roller pair 3e and discharged to the discharge section 6.

On the other hand, in the process cartridge B constituting the image forming section, as shown in FIGS. 1 and 2, a photosensitive drum 7 having a photosensitive layer on a cylindrical surface of aluminum is rotated and the surface thereof is charged by a charging means. It is uniformly charged by applying a voltage to a certain charging roller 8, and the optical image from the optical system 1 is exposed on the photosensitive drum 7 through the exposure unit 9 to form a latent image, which is developed by the developing means 10. . This developing means 10
The toner in the toner reservoir 10a is fed by the toner feeding member 10b, the developing roller 10d having the fixed magnet 10c built therein is rotated, and a toner layer to which a triboelectric charge is applied by the developing blade 10e is formed on the surface of the developing roller 10d. By transferring the toner to the photosensitive drum 7 according to the latent image, a toner image is formed and visualized.

Then, after a voltage having a polarity opposite to that of the toner image is applied to the transfer roller 4 to transfer the toner image onto the recording medium 2, the cleaning blade 11a is used for the photosensitive drum 7.
Scrape off the toner remaining on the
The residual toner on the photoconductor drum 7 is removed by the cleaning means 11 which collects the waste toner in the waste toner reservoir 11c.

Each component such as the photosensitive drum 7 holds a toner container 12a forming a toner reservoir 10a, a developing frame 12b holding a developing roller 10d, a photosensitive drum 7, a charging roller 8 and a cleaning means 11. Cleaning frame
12c and a shutter member 12d for protecting the photoconductor drum 7 from exposure to radiation are housed in a housing constituted by combining them and made into a cartridge, which is detachably attached to a cartridge attaching means provided in the apparatus main body 13. It

The cartridge is mounted by opening the front unit 14 of the apparatus main body 13 as shown in FIG. That is, a front unit 14 that can be opened and closed by a hinge 14a is attached to the front portion of the apparatus body 13, and when the front unit 14 is opened, cartridge mounting means is provided in the apparatus body 13.

As shown in FIG. 3, the cartridge mounting means comprises a drum pin 15 for pivotally supporting the photosensitive drum 7, and
A guide part 16 formed outside the cleaning frame 12c and a click spring part 17 having a spring property are provided on both side surfaces. On the other hand, the device body 13 has a click hole in which a guide hole portion 18 for guiding the guide portion 16 and a click spring portion 17 are inserted.
Positioning portions 20 for positioning the photosensitive drum 7 and the photosensitive drum 7 are formed on both side surfaces. Therefore, the process cartridge B is positioned and mounted in the image forming apparatus A by inserting the guide portion 16 of the process cartridge B along the guide hole portion 18. Then, when the process cartridge B is mounted, the drum drive gear 21 axially supported on the side surface of the apparatus main body 13 is attached to the photosensitive drum 7, and the drum gear 22 (see FIG.
Driving force can be transmitted to the photoconductor drum 7.

The shutter member 12d is opened and closed centering on the shaft 12d1 (see FIG. 2) along with the attachment / detachment of the process cartridge B by an opening / closing mechanism (not shown).
When the cartridge B is attached to the image forming apparatus A, the cartridge B is opened, and when the cartridge B is removed from the image forming apparatus A, the cartridge B is closed.

{Structure of Electric Contact Member} Next, the structure of the electric contact member for electrically connecting the charging roller 8 and the apparatus main body 13 will be described.

As shown in the sectional view of FIG. 4, the charging roller 8 has a conductive elastic layer 8b on a cored bar 8a, a high resistance elastic layer 8c thereon, and a protective film 8d on the surface. Have. The cored bar 8a has conductivity, and by supplying a bias voltage to the cored bar 8a, the surface of the photosensitive drum 7 is uniformly charged via the charging roller 8.

As shown in FIG. 5, both ends of the cored bar 8a are supported by bearings 23, and the bearings 23 are provided with the cleaning frame 12c and the bearings.
By being urged in the direction of the photosensitive drum 7 by a spring 24 which is contracted between the photosensitive drum 7 and 23, the photosensitive drum 7 comes into a predetermined pressure contact with the photosensitive drum 7 and is rotated by the rotation of the photosensitive drum 7. It has become.

A cap 25 as an electric contact member is covered on the end face of the cored bar 8a in the thrust direction, and the electrode 26 is elastically contacted with the cap 25 with a load of 50 to 200 gf. Then, the process cartridge B is the apparatus main body 13
When mounted by the mounting means, the power receiving terminal 27 on the side of the process cartridge B and the power feeding terminal 28 on the side of the apparatus main body 13 come into contact with each other, and the power source 29 on the side of the apparatus main body 13 and the process cartridge B
The side electrode 27 is electrically connected.

Here, the cap as the electric contact member
The reference numeral 25 is made of a conductive material for making a resin material such as polyphenylene sulfide (hereinafter referred to as “PPS”) have conductivity, for example, a conductive resin filled with carbon fiber or the like.

It is often said that the PPS is excellent in insulation as one of the properties common to polymer materials, and the PPS also has good insulation and arc resistance even under high temperature and high humidity. Have sex. However, “the new technology of imparting conductivity to polymers, the actual development of new applications and their practical application-
On page 126 of "Comprehensive Materials Collection" (published by Chubu Business Development Center, January 25, 1983)
PS has a specific resistance of about 10 ⁶ Ωcm, but when exposed to AsF ₅ vapor, the specific resistance becomes 1 Ωcm, and the conductivity is improved 10 ⁶ times by doping with AsF ₅ . According to crystal analysis, adjacent Ferni rings are tilted ± 45 ° with respect to the plane formed by sulfur. Therefore, it is possible that the electrons are delocalized in the polymer via the d orbital of sulfur to improve the conductivity. Is stated.

Further, since PPS is generally excellent in fluidity and heat resistance, it is possible to increase the filling amount of the conductive substance as compared with other resins, and to increase the filling amount of the conductive substance. By doing so, the moldability is slightly deteriorated, but it is superior to other resins.

Therefore, PPS is suitable as a base resin for a conductive resin, since the resin itself is potentially conductive and the amount of conductive material can be increased.

Regarding the conductive substance filled in the PPS, a substance having a smaller size is more likely to be uniformly dispersed up to the surface portion of the resin, and stable conductivity can be obtained. However, if it is too small, it becomes difficult for the conductive substances to come into contact with each other, and it becomes difficult to form a conductive path. Therefore, the size of the conductive substance is 5 to 20 μm for the fiber diameter.
It is preferable to use a fiber having a length of m and a fiber length of 100 to 500 μm.
Furthermore, the higher the content of the conductive substance, the better the conductivity. For example, when the content rate was 30%, the resistance value was 50 to 150Ω. If the content is 30% or less, the resistance value increases and the stability is poor. When the content is 30% or more, the resistance value decreases and the stability also improves. However, if the content is too high, moldability and the like gradually become a problem.

Therefore, the content rate of the conductive material should be set to an optimum value in accordance with the required conductive performance, usage conditions and the like. In this example, as the conductive material to be filled, stable conductivity was obtained when the carbon fiber content was in the range of 20 to 50%, and good image formation was possible.

The contact pressure between the cap 25 and the electrode 26 ensures contact between them, and the metal bar 8a on the side opposite to the side on which the cap 25 is provided hits the cleaning frame 12c by pressing the electrode 26. Suppressing scraping of the frame 12c,
Moreover, in order to reduce the rotation load of the core metal 8a, about 50-200gf
It is preferable to make the load low.

In this embodiment, in order to make the contact between the cap 25 and the electrode 26 more reliable, as shown in FIG. 6, a projection 25a having a triangular cross section (may be a semicircle or the like) is formed on the contact end surface of the cap 25. At least two or more are provided. This is because if the conductive material filled in the conductive resin forming the cap 25 is unevenly dispersed in the resin, a conductive path due to the conductive material is not formed between the electrode 26 and the cored bar 8a, and the conductive failure is caused. Occur. At this time, if the protrusion 25a is provided as described above,
The conductive substance is locally concentrated on the protrusion 25a, and the conductive substance is sufficiently protruded at the tip of the protrusion 25a.
When contacting the protrusion 25a with a constant load, the electrode 26 and the cap
Stable conductive performance can be obtained by contact with the conductive material sufficiently protruding from the tips of the projections 25a of 25.

As shown in FIGS. 7 and 8, the cap is
The contact end surface of 25 may be provided with a ring-shaped protrusion 25b. The cap 25 provided with the protrusion 25b can also obtain stable conductive performance similarly to the cap 25 provided with two or more protrusions 25a. It is preferable that the cap 25 provided with the ring-shaped protrusion 25b is brought into contact with the electrode 26 'having a two-leg contact terminal with a low load of about 50 to 200 gf.

As described above, by forming the cap 25 as an electric contact member that comes into contact with the electrodes 26, 26 'by the conductive resin, even if the electrodes 25, 26' made of metal are rubbed, abnormal noise is generated. No strange noise is produced. Therefore, unlike the conventional case, it is not necessary to apply grease or the like to the contact portion, and the assembling process of the charging roller 8 can be automated.

[Other Embodiments] The process cartridge B according to the present invention described above is not limited to the case of forming a single color image as described above, but a plurality of developing means are provided and a plurality of color images (for example, a two color image, It can also be suitably applied to a cartridge that forms a three-color image or full-color image.

As the developing method, various known developing methods such as a two-component magnetic brush developing method, a cascade developing method, a touchdown developing method and a cloud developing method can be used.

The photoconductor is not limited to the photoconductor drum, but includes the following, for example. First, a photoconductor is used as the photoconductor, and examples of the photoconductor include amorphous silicon, amorphous selenium, zinc oxide, titanium oxide, and organic photoconductor (OPC). The shape on which the photoconductor is mounted includes, for example, a drum-shaped, belt-shaped rotating body, a sheet-shaped body, and the like. Generally, a drum-shaped or belt-shaped one is used. For example, in the case of a drum type photoconductor, a photoconductor is vapor-deposited or coated on a cylinder of aluminum alloy or the like. Is.

Further, as a method for cleaning the toner remaining on the photosensitive drum, the cleaning means may be constituted by using a blade, a fur brush, a magnetic brush or the like.

In the above-mentioned embodiment, the photosensitive drum, the developing roller, etc. are made into a cartridge, and the process cartridge is mounted to form an image. However, the photosensitive drum, the developing roller, etc. are made into a cartridge. Alternatively, even an image forming apparatus directly attached to the apparatus body can be applied to the present invention.

That is, the photosensitive drum and charging means for uniformly charging the photosensitive drum, developing means for forming a toner image on the photosensitive drum, and the toner image formed on the photosensitive drum are transferred to a recording medium. In an image forming apparatus having an image forming apparatus having a transfer means for carrying out, a carrying means for carrying a recording medium, etc. in the apparatus body, an electric contact member for electrically connecting a charging roller and a power source of the apparatus body is made of a resin made of PPS. It is composed of a conductive resin member in which a conductive material is filled, and is placed between the core metal of the charging roller and the electrode to rub against it.
The same effect can be obtained even when the electric contact member is configured to come into contact through the protrusion provided on the electric contact member .

Further, although the laser beam printer is exemplified as the image forming apparatus in the above-mentioned embodiment, the present invention is not limited to this, and other image forming apparatus such as an electrophotographic copying machine, a facsimile machine, a word processor, etc. It is also possible to use for.

[0043]

As described above, according to the present invention, when electrically connecting the charging roller and the apparatus main body, the PPS is applied to the rubbing portion.
Since the connection is made through the resin member, it is possible to prevent the abnormal noise and the abnormal noise from being generated from the rubbing portion.

At this time, the rubbing portion is the electric contact member.
The conductive material is locally concentrated on the protrusions, so that stable conductive performance can be obtained with a constant contact load.

Further, since it is not necessary to apply conductive grease or the like to the rubbing portion as in the conventional case, it is possible to automate the assembly production line.

[Brief description of drawings]

FIG. 1 is a configuration explanatory view of an image forming apparatus with a process cartridge attached.

FIG. 2 is an explanatory diagram of a configuration of a process cartridge.

FIG. 3 is an explanatory diagram of a cartridge mounting configuration.

FIG. 4 is a cross-sectional explanatory diagram of a charging roller.

FIG. 5 is an explanatory diagram of a power supply configuration to a charging roller.

FIG. 6 is an explanatory diagram of a cap end surface.

FIG. 7 is an explanatory diagram of a power supply configuration to a charging roller.

FIG. 8 is an explanatory diagram of an end surface of the cap.

[Explanation of symbols]

1 ... Optical system, 2 ... Recording medium, 3 ... Conveying means, 3a ... Cassette, 3b ... Pickup roller, 3c ... Registration roller, 3d ... Guide plate, 3e ... Ejection roller, 4 ... Transfer roller, 5 ... Fixing means, 5a ... drive roller, 5b ... fixing roller, 6 ... discharge section, 7 ... photoconductor drum, 8 ... charging roller,
8a ... core metal, 8b ... elastic layer, 8c ... elastic layer, 8d ... protective film, 9 ... exposure part, 10 ... developing means, 10a ... toner reservoir, 10
b ... toner feeding member, 10c ... magnet, 10d ... developing roller,
10e ... Developing blade, 11 ... Cleaning means, 11a ... Cleaning blade, 11b ... Squeeze sheet, 11c ... Waste toner reservoir, 12a toner container, 12b ... Developing frame body, 12c ... Cleaning frame body, 12d ... Shutter member, 13 ... Device body ,
14 ... Front unit, 14a ... Hinge, 15 ... Drum pin, 16 ...
Guide part, 17 ... Click spring part, 18 ... Guide hole part, 19 ...
Click recess, 20 ... Positioning part, 21 ... Drive gear, 22 ... Drum gear, 23 ... Bearing, 24 ... Spring, 25 ... Cap, 25a,
25b ... Protrusion, 26, 26 '... Electrode, 27 ... Power receiving terminal, 28 ... Power feeding terminal, 29 ... Power supply

─────────────────────────────────────────────────── --- Continuation of front page (56) Reference JP-A-6-89069 (JP, A) JP-A-60-206864 (JP, A) JP-A-62-27458 (JP, A) JP-A-56- 135549 (JP, A) JP-A-2-29677 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) G03G 15/00 G03G 15/00 550 G03G 21 / 16-21 / 18

Claims (4)

(57) [Claims] 1. A process cartridge attachable to and detachable from an image forming apparatus main body, comprising: a photosensitive drum; a charging roller having a conductive cored bar for charging the photosensitive drum; And a power receiving terminal for receiving a bias voltage for applying to the charging roller from the device body when the device is attached to the device body, and a power receiving terminal electrically connected to the power receiving terminal. An electrode to be connected, and the core metal for supplying the bias voltage to the core metal
And an electric contact member interposed between the electrode and
An electrical contact member made of a conductive resin member in which a conductive material is filled in a resin material made of polyphenylene sulfide , and an electric contact member having a protrusion in a portion that rubs against the electrode. A process cartridge, wherein the bias voltage is applied to the charging roller via an electric contact member made of a conductive resin member and a cored bar. 2. The conductive material filled in the resin material is carbon fiber having a fiber diameter of 5 to 20 μm and a fiber length of 100 to 500 μm, and the filling rate of the resin material is 20 to 50%. The process cartridge according to claim 1, wherein 3. The process cartridge according to claim 1, wherein the protruding portion of the electric contact member is configured to be brought into contact with another electric contact member with a load of 50 to 200 gf. 4. An image forming apparatus for forming an image on a recording medium, wherein a process cartridge is attachable / detachable, and which has a photosensitive drum and a conductive cored bar, and is for charging the photosensitive drum. When the roller and the process cartridge are mounted in the apparatus body, the power receiving terminal is in contact with a power supply terminal provided in the apparatus body and receives a bias voltage to be applied to the charging roller from the apparatus body. And an electrode electrically connected to the power receiving terminal,
The core metal for supplying the bias voltage to the core metal
And an electric contact member interposed between the electrode and
The electric contact member is formed of a conductive resin member having a conductive material filled in a resin material made of polyphenylene sulfide , and has a projection in a portion that rubs against the electrode. And a mounting means for mounting a process cartridge for applying the bias voltage to the charging roller via a core metal, and an electric contact member made of a conductive resin member, and an image formed on the photosensitive drum as a recording medium. An image forming apparatus comprising: a transfer unit for transferring to a recording medium; and a conveying unit for conveying a recording medium.