JPH11184352A - Process cartridge - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a process cartridge more excellent than a conventional process cartridge. SOLUTION: An image carrier 2 is rotatably attached to a receiving aperture 14A provided on a waste developer storage part 14 and receiving developer removed by a cleaning member 4 removing the developer adhering to the image carrier 2 in a state where a part of the carrier 2 is exposed. The aperture 14A is covered with the carrier 2, the member 1l and a developer leakage preventing member 15 so as to hermetically seal the inside S of the storage part 14. Meanwhile, by forming a communicating aperture 18 on the hermetically sealed storage part 14 so that the inside S may communicate with the outside, the surface of the carrier 2 positioned on the inside S and the outside of the storage part 14 respectively is exposed in the same atmosphere. Thus, the adapting speed of the carrier 2 to environment is made equal and irregular image density can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process cartridge removably mounted on a main body of an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile, and the like, and more particularly, to the prevention of image density unevenness.

[0002]

2. Description of the Related Art Conventionally, an electrophotographic image forming apparatus such as a printer, a copying machine, a facsimile, etc., which is detachably mounted on a main body, has at least an image carrier, and a cleaning member for removing a developer adhered to the image carrier. There is also provided a process cartridge having a receiving opening for receiving the developer removed by the cleaning member, and a waste developer accommodating portion in which an image carrier is rotatably attached to the receiving opening in a partially exposed state. .

FIG. 11 is a sectional view showing an example of such a conventional process cartridge, and FIG. 12 is a sectional view showing an example of an electrophotographic image forming apparatus in which the process cartridge is detachably mounted. .

A photosensitive drum 2 as an image carrier is rotatably mounted on the process cartridge 1, and a charging roller 3 as a contact charging member and a cleaning blade 4 as a cleaning member abut on the photosensitive drum 2. Installed.

A main body 5a of the electrophotographic image forming apparatus 5
A vibration voltage in which an AC voltage and a DC voltage are superimposed is applied to the process cartridge 1 mounted on the photosensitive drum 2 via the charging roller 3, whereby the peripheral surface of the photosensitive drum 2 is subjected to a contact charging process to obtain a predetermined charge. It has become.

When an image is formed, the charged surface of the photosensitive drum 2 is scanned and exposed by a laser beam emitted from a laser scanner 7 mounted on the image forming apparatus, so that the desired image information is obtained. An electrostatic latent image is formed. Then, the latent image formed on the photosensitive drum is developed by attaching a toner as a developer by a developing device 8 arranged to face the photosensitive drum 2. Further, the image formed on the photosensitive drum is conveyed in the order of the transfer unit 9 and the fixing unit 10 provided in the image forming apparatus main body 5a, and the fixed image on the recording paper 11 is completed.

On the other hand, the toner remaining on the photosensitive drum 2 at the time of transfer is scraped off by the cleaning blade 4 and removed before the photosensitive drum 2 is charged again. Then, the removed toner is collected by the rake member 13 disposed in contact with the photosensitive drum 2, and is received from the receiving opening 14A formed in the waste toner accommodating portion 14, which is the waste developer accommodating portion. The toner is accumulated in the waste toner container. The rake member 13 has a receiving opening 14A.
It also plays a role in preventing toner from leaking from the toner cartridge.

Incidentally, there are places at both ends of the photosensitive drum 2 where the cleaning blade 4 and the rake member 13 do not come into contact. To prevent leakage of waste toner from a gap formed at this place, as shown in FIG. Then, a toner leakage prevention member 15 formed of felt or the like is attached.

[0010] In addition to those described with reference to FIG. 11, there are process cartridges in which members necessary for image formation are unitized, including those integrating a developing unit and those omitting a charging member. In any of the process cartridges, the receiving opening 14 is provided to prevent leakage of waste toner.
A is tightly sealed.

On the other hand, in the electrophotographic image forming apparatus, as shown in FIG. 14, a subbing layer 2b, a charge generation layer 2c and a charge transport layer 2d are sequentially formed on a conductive substrate 2a as a photosensitive member (photosensitive drum) 2. Laminated ones are generally used. In particular, since an organic substance is used as a material of the charge generation layer 2c and the charge transport layer 2d, such a photoconductor is called an organic photoconductor.

Here, it is known that various characteristics of such an organic photoreceptor change depending on ambient temperature and humidity. FIGS. 15 and 16 are graphs showing how the potential (VL) changes according to temperature and humidity when a certain organic photoreceptor is charged to a certain potential and then exposed with a certain amount of light. It is.

Note that these characteristic changes often change slowly rather than instantaneously when the environment changes. This is affected by the incompatibility of the material used in the organic photoreceptor with the environment, and organic photosensitive materials having higher environmental adaptability are being actively studied.

By the way, in the process cartridge 1 described with reference to FIG. 11, the surface of the photosensitive drum 2 is exposed from the waste toner accommodating portion 14, that is, the cartridge container (hereinafter, the waste toner accommodating portion is referred to as a cartridge container) 14, There is a portion facing the inside S of the cartridge container sealed with the container 14, the cleaning blade 4, the rake member 13, and the toner leakage prevention member 15.

Here, when the temperature and humidity around the process cartridge 1 are changed and left in the environment for a certain period of time, the speed (aging speed) at which the photosensitive drum 2 adapts to the environment inside and outside the cartridge container 14 differs. As a result, the potential (VL) at the time of exposure of the photosensitive drum 2 changes over the entire circumference of the photosensitive drum.

When an image is formed on such a photosensitive drum 2, density unevenness occurs in portions having different potentials (VL), and the image quality is significantly reduced. However, the potential difference generated over the entire circumference of the photosensitive drum gradually decreases as the aging of the surface of the photosensitive drum facing the space inside the cartridge container progresses as time passes to the environment.

The change in the potential (VL) of the photosensitive drum 2 due to the temperature and humidity is caused not only when the process cartridge itself is moved to a different environment, but also when the process cartridge itself is moved to a different environment.
It also occurs due to an environmental change inside the apparatus that occurs when an image is formed by mounting the process cartridge in the image forming apparatus.

[0017]

SUMMARY OF THE INVENTION An object of the present invention is to provide a process cartridge which is superior to a conventional process cartridge.

[0018]

According to the present invention, at least an image carrier, which is detachably mounted on the main body of an electrophotographic image forming apparatus, and a cleaning member for removing a developer adhered to the image carrier, Having a receiving opening for receiving the developer removed by the cleaning member;
A process cartridge having a waste developer accommodating portion rotatably mounting the image carrier in the receiving opening while partially exposing the image carrier, wherein the image carrier, the cleaning member, and the developer leakage preventing member A communication opening for communicating between the inside and the outside of the waste developer accommodating portion, which is closed and closed by the receiving opening, is formed in the waste developer accommodating portion.

Further, the present invention is characterized in that the communication opening is closed with a sealing member having air permeability.

Further, according to the present invention, when air blowing means is provided inside the electrophotographic image forming apparatus main body, air from the air blowing means can flow into the waste developer accommodating section through the communication opening. It is formed at a position.

Further, the present invention is characterized in that the communication opening is formed in a bottom surface of the waste developer accommodating portion.

Further, the present invention is characterized in that the waste developer accommodating portion is provided with an exhaust opening for exhausting the air blown from the air blowing means flowing through the communication opening.

Further, the present invention is characterized in that the exhaust opening is provided at a position where air from the air blowing means does not flow.

Further, the present invention is characterized in that the exhaust opening is closed with a sealing member having air permeability.

Further, as in the present invention, the image carrier is partially accommodated in the receiving opening provided in the waste developer accommodating portion and for receiving the developer removed by the cleaning member for removing the developer attached to the image carrier. Is rotatably mounted in a state where is exposed, and the receiving opening is closed by an image carrier, a cleaning member, and a developer leakage preventing member, thereby sealing the inside of the waste developer accommodating portion. On the other hand, by forming a communication opening in the sealed waste developer storage unit to communicate the inside and the outside of the waste developer storage unit, the image carrier surfaces located inside and outside the waste developer storage unit, The image carrier can be exposed to the same atmosphere, and the speed at which the image carrier adapts to the environment can be equalized.

[0026]

Embodiments of the present invention will be described below.

FIG. 1 is a sectional view of a process cartridge according to a first embodiment of the present invention. In the figure, the same reference numerals as those in FIG. 11 indicate the same or corresponding parts.

In FIG. 1, reference numeral 16 denotes a process cartridge, which is a unit in which the photosensitive drum 2, the charging roller 3, and the cleaning blade 4 are integrated, and which is detachable from the main body of the image forming apparatus as a replacement unit. It was done.

Numeral 18 denotes a cartridge container 14 for rotatably holding the photosensitive drum 2 so that a part thereof is exposed and the remaining part faces the receiving opening 14A, the cleaning blade 4, the rake member 13, the toner A communication opening formed in the cartridge container 14 to allow communication between the inside S of the cartridge container sealed with the leakage prevention member 15 and the outside.

The communication between the inside S of the cartridge container and the outside as described above allows air to freely flow through the inside S of the cartridge container through the communication opening 18, whereby the inside and outside of the cartridge container can be respectively connected. Can be exposed to the same atmosphere.

Here, by exposing the surface of the photosensitive drum 2 to the same atmosphere as described above, the aging speed of the photosensitive drum 2 inside and outside of the cartridge container becomes substantially equal, thereby changing the temperature and humidity around the process cartridge. Even in this case, partial potential fluctuation does not occur on the surface of the photosensitive drum, and the occurrence of image density unevenness due to this is prevented.

The process cartridge 16 of this embodiment and the conventional process cartridge 1 (see FIG. 11)
Is left in a normal temperature and normal humidity environment (23 ° C./60%) for 24 hours, then transferred to a low temperature and low humidity environment (10 ° C./5%), and a halftone image is output every other hour in the same environment, and the comparison is performed. As a result, the table shown in FIG. 2 was obtained. Here, in the same figure, x indicates a case where density unevenness has occurred, and 〇 indicates a case where density unevenness has not occurred.

As shown in FIG. 2, in the conventional process cartridge 1, density unevenness occurs on the halftone image even after 3 hours, whereas in the process cartridge 16 of the present embodiment, it is left untreated. One hour later, image unevenness has not already occurred in image output.

As described above, the communication opening 18 is formed in the cartridge container 14, and the air can freely flow in and out of the cartridge container S through the communication opening 18. The aging speed of the surface can be made almost equal. As a result, even when the temperature and humidity around the process cartridge change, it is possible to suppress the occurrence of partial potential fluctuation on the surface of the photosensitive drum, and to prevent the occurrence of uneven image density.

Next, a second embodiment of the present invention will be described.

FIG. 3 is a sectional view of a process cartridge according to the present embodiment, and FIG. 4 is a sectional view of an electrophotographic image forming apparatus in which the process cartridge is detachably mounted. In FIG. 3, the same reference numerals as those in FIG. 1 and in FIG. 4, the same reference numerals as those in FIG. 12 indicate the same or corresponding parts, respectively.

In FIG. 3, reference numeral 19 denotes a process cartridge. The process cartridge 19 integrates the photosensitive drum 2, the charging roller 3, and the cleaning blade 4, and is detachable from the image forming apparatus main body as a replacement unit. .

In the same figure, reference numeral 17 denotes a communication opening formed in the cartridge container 14 for communicating the inside S of the cartridge container with the outside. Here, as shown in FIG. 4, when the electrophotographic image forming apparatus 5 is operated, the communication opening 17 is provided with an air flow (blowing) 24 generated inside the main body by an electric fan 23 which is a blowing means provided in the main body 5a. Is formed on the bottom of the cartridge container 14 shown in FIG. In FIG. 4, reference numeral 28 denotes a recording paper storage unit that stores and stores the recording paper 11, and 29 denotes a transport device that transports the recording paper 11 to the process cartridge 19.

The communication opening 17 allows the inside S of the cartridge container to communicate with the outside, thereby reducing the aging speed of the photosensitive drum 2 inside and outside the cartridge container, as in the first embodiment described above. The values can be made substantially equal, and the occurrence of uneven image density can be prevented.

On the other hand, the communication opening 17 is closed by a seal member 25 made of a fluorine-based compound sheet of a porous film having air permeability. And
By closing the communication opening 17 with the air-permeable sealing member 25 in this way, it is possible to prevent toner from leaking from the cartridge container 14 without preventing air from flowing in and out of the communication opening 17.

Further, this allows the communication opening 17 to be formed in a place where the toner naturally falls and blows out of the container, for example, in the lower part of the cartridge container, and the communication opening 17 is formed. The degree of freedom in selecting a place to be performed can be increased.

In order to test the effect of preventing image density unevenness in the process cartridge 19 according to the present embodiment, the process cartridge 19 is mounted on the electrophotographic image forming apparatus 5 shown in FIG. %)
An experiment was conducted to output images continuously.

In the electrophotographic image forming apparatus 5, during the above-described image forming operation, the internal temperature and humidity are determined by the environment around the image forming apparatus, heat generated by the fixing unit 10 and a power supply unit (not shown), and the like.
It changes sequentially under the influence of moisture and the like contained in the recording paper 11.
For this reason, in this experiment, image density unevenness was checked every 20 A4 sheets of printing, and at the same time, the temperature and humidity in the image forming apparatus and the temperature and humidity of the cartridge container 19 were measured. For comparison, the conventional process cartridge 1
The same measurement was carried out for.

The results of the experiment are as shown in FIGS. FIG. 5 shows the temperature change inside and outside the cartridge container of the present embodiment, FIG. 6 shows the temperature change inside and outside the conventional cartridge container, and FIG. 7 shows the presence / absence of image density unevenness.

Here, according to FIG. 5, in the process cartridge 19 of the present embodiment, the air flow 24 flows into the inside of the cartridge container S through the communication opening 17 provided in the cartridge container 19, whereby the cartridge container It can be seen that the same temperature and humidity as in the outside are obtained.

On the other hand, in the conventional process cartridge 1, as shown in FIG. 6, there is a deviation in temperature and humidity inside and outside the cartridge container, and as a result, as shown in FIG. .

As described above, the communication opening 17 is formed in the cartridge container 14, and the airflow flows from the communication opening 17 into the inside S of the cartridge container.
The temperature and the humidity inside the cartridge container S can be changed quickly in accordance with the temperature and the humidity inside the image forming apparatus which are significantly changed by the operation. Thereby, it is possible to prevent the occurrence of uneven image density due to the different aging speed of the photosensitive drum 2 inside and outside the cartridge container 14.

In this embodiment, a porous fluorine-containing compound sheet is used as the gas-permeable seal member 25. However, other materials may be used as long as they are gas-permeable and hinder the passage of toner. Instead, for example, urethane foam may be used.

Next, a third embodiment of the present invention will be described.

FIG. 8 is a sectional view of the process cartridge according to the present embodiment. In the figure, the same reference numerals as those in FIG. 3 indicate the same or corresponding parts.

In the same figure, reference numeral 30 denotes a process cartridge, and the cartridge container 14 of the process cartridge 30 has the same communication opening 17 as that of the second embodiment described above, and the communication opening 17. A discharge opening 32 is formed to discharge the airflow that has flowed into the cartridge container interior S from the outlet. The discharge opening 32 is formed at a position where the airflow does not flow.

Here, the cartridge container 14
By providing the discharge opening 32 in the communication opening 17
The inflowing airflow is smoothly discharged from the discharge opening 32 to the outside of the force cartridge container.

Thus, the exchange of the air inside the cartridge container S can be performed more smoothly, and the temperature and humidity inside the cartridge container are quickly changed in accordance with the temperature and humidity inside the image forming apparatus, which greatly changes due to the operation. be able to. Therefore, it is possible to prevent the occurrence of uneven image density due to the different aging speed of the photosensitive drum 2 inside and outside the cartridge container 14.

By the way, the discharge opening 32 is closed by a seal member 25 made of a fluorine-based compound sheet of a porous film having air permeability. By closing the discharge opening 32 with the air-permeable seal member 25 in this way, it is possible to prevent toner from leaking from the cartridge container 14 without obstructing discharge of air from the discharge opening 32.

In order to examine the effect of this embodiment,
A cross-sectional model of the process cartridge 30 was created and housed in, for example, the electrophotographic image forming apparatus 5 shown in FIG. 4, and the movement of air in the cartridge container during image formation was observed by capturing the flow of smoke of incense.

FIG. 9 is a view showing the state at that time. It can be seen that the air flow smoothly passes through the communication opening 17 on the air flow inflow side to the discharge opening 32 as shown in FIG.

A similar experiment was conducted with the process cartridge 19 according to the second embodiment, and the flow of air was as shown in FIG. That is, in the process cartridge 19, the air flowing from the communication opening 17 forms a convection in the cartridge container 14 and is discharged to the outside of the cartridge container again through the communication opening 17.

As described above, in the present embodiment, the air that has flowed into the cartridge container through the communication opening 17 is discharged out of the cartridge container through the discharge opening 32. Therefore, the exchange of the air inside the cartridge container S can be performed more smoothly, and the temperature and humidity inside the cartridge container can be quickly changed in accordance with the temperature and humidity inside the image forming apparatus, which sequentially changes with the operation. . Thereby, it is possible to prevent the occurrence of uneven image density due to the different aging speed of the photosensitive drum 2 inside and outside the cartridge container.

[0059]

As described above, according to the present invention, the inside and outside of the waste developer accommodating portion are similarly brought into contact with each other by connecting the inside and the outside of the closed waste developer accommodating portion. And the speed at which the image carrier adapts to the environment can be equalized. Thus, it is possible to prevent the occurrence of uneven image density due to the different aging speeds of the image carrier inside and outside the waste developer storage section.

[Brief description of the drawings]

FIG. 1 is a sectional view of a process cartridge according to a first embodiment of the present invention.

FIG. 2 is a table showing whether or not density unevenness occurs when an image is formed using the process cartridge and a conventional process cartridge.

FIG. 3 is a sectional view of a process cartridge according to a second embodiment of the present invention.

FIG. 4 is a sectional view of an electrophotographic image forming apparatus in which the process cartridge is detachably mounted.

FIG. 5 is a table showing temperature changes inside and outside the cartridge container during image formation of the process cartridge according to the second embodiment.

FIG. 6 is a table showing temperature changes inside and outside a cartridge container during image formation of a conventional process cartridge.

FIG. 7 is a table showing whether or not density unevenness has occurred when an image is formed using the process cartridge according to the second embodiment and a conventional process cartridge.

FIG. 8 is a sectional view of a process cartridge according to a third embodiment of the present invention.

FIG. 9 is a diagram illustrating the movement of air inside a cartridge container according to the third embodiment.

FIG. 10 is a view for explaining the movement of air inside the cartridge container according to the second embodiment.

FIG. 11 is a sectional view of an example of a conventional process cartridge.

FIG. 12 is a cross-sectional view of an electrophotographic image forming apparatus in which the conventional process cartridge is detachably mounted.

FIG. 13 is a diagram illustrating an arrangement of a toner leakage prevention member of a conventional process cartridge.

FIG. 14 illustrates a general organic photoreceptor.

FIG. 15 is a table illustrating the temperature dependence of the potential of the general organic photoreceptor.

FIG. 16 is a chart for explaining the humidity dependency of the potential of the general organic photoreceptor.

[Explanation of symbols]

1, 16, 30 Process Cartridge 2 Photosensitive Drum 3 Charging Roller 4 Cleaning Blade 5 Electrophotographic Image Forming Apparatus 5a Electrophotographic Image Forming Apparatus Main Body 13 Rake Member 14 Waste Toner Container (Cartridge Container) 14A Receiving Opening 15 Toner Leakage Prevention Member 17 , 18 communication opening 25 seal member 32 exhaust opening

Claims (7)

[Claims] An image carrier, a cleaning member that removes a developer adhered to the image carrier, and a developing device that is removed by the cleaning member. A process cartridge having a receiving opening for receiving the developer, and a waste developer accommodating portion rotatably mounting the image carrier in the receiving opening in a state where a part of the image carrier is exposed. A communication opening for communicating between the inside and the outside of the waste developer accommodating portion, which is closed and closed by the cleaning member and the developer leakage prevention member, is formed in the waste developer accommodating portion. Characteristic process cartridge. 2. The process cartridge according to claim 1, wherein the communication opening is closed with a seal member having air permeability. 3. When an air blowing means is provided inside the electrophotographic image forming apparatus main body, the communication opening is formed at a position where air from the air blowing means can flow into the waste developer accommodating portion. The process cartridge according to claim 1, wherein 4. The process cartridge according to claim 3, wherein said communication opening is formed in a bottom surface of said waste developer accommodating portion. 5. The process according to claim 3, wherein the waste developer accommodating section is provided with an exhaust opening for exhausting the air blown from the air blowing means flowing from the communication opening. cartridge. 6. The air outlet according to claim 5, wherein the air outlet is provided at a position where air from the air blower does not flow.
The process cartridge as described. 7. The exhaust opening is closed with a gas-permeable seal member.
The process cartridge as described.