JP4606893B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an agitating member, a developing device, a process cartridge, and an image forming apparatus including these in an image forming apparatus such as a copying machine, a printer, and a facsimile machine.

In recent years, widespread use of full-color image forming apparatuses has led to demands for higher image quality, smaller size, and improved convenience. In particular, the performance of the developing device that forms a visible image by attaching toner to the electrostatic latent image on the surface of the photoreceptor greatly affects the image quality. For this reason, a two-component developing method using toner as a carrier is widely used, and in order to reliably mix the developer, many developments such as rotating the developer stirring member to increase the stirring force have been made. .
However, when the rotation speed of the stirring member is increased, especially when the developing device is continuously operated, both ends in the rotation axis direction of the stirring member rise in temperature, so that the two-component developer in the developing device deteriorates, The image quality deteriorates due to poor charging of the developer. Further, when the toner in the developing device is overheated, the toner is melted, and then the toner aggregates and solidifies, and the solidified toner is fixed in the developing device. In particular, when the solidified toner adheres to the bearing portion of the stirring member, there is a problem in that the rotation does not occur unless the torque of the rotating shaft is increased, and the rotating shaft is finally locked and cannot operate.

As a prior art improved to prevent the temperature of the stirring member from increasing, a thick portion and a thin portion are provided in the stirring member, and the ratio of the length in the radial direction of the thin portion in the stirring member is the rotation axis. configure it towards the end from the central portion in the direction is increased, the rigidity of said end portion is agitating member was lower than the central portion (e.g., Patent Document 1 see). Further, the developing in which a vent is formed to communicate the space between the bearing member and the seal member in the axial direction to the outside of the developing device so as to dissipate heat at both ends in the axial direction of the developer conveying member to the outside of the developing device. device has (e.g., Patent Document 2 see). Further, there is an image forming apparatus in which an intake fan and an exhaust fan are provided with a process cartridge interposed therebetween, and an air passage is configured to generate an air flow between the process cartridge and the fixing device (for example, Patent Document 3). see).

JP 2003-005498 A JP 2003-057927 A JP 2004-205651 A

  The above prior art does not provide a space by reducing the size of the stirring member and the process cartridge itself, so that the temperature rise of the stirring member is not sufficiently suppressed. In addition, since the air passage is not provided in the image forming apparatus in consideration of the gap between the units, if there are many gaps between the units around the process cartridge, the effect of the space formed as an air passage is sufficient. Cannot be used. This is because air flows in and out from other gaps, so that the space at the end of the process cartridge cannot function as an air path for cooling, and the function of suppressing the temperature rise at the end of the process cartridge is reduced. It is.

  The present invention has been made in view of the above problems, suppresses the temperature rise of the stirring member, prevents an excessive load from being applied to the rotating shaft of the stirring member, prevents deterioration of the developer, and achieves high image quality. The purpose is to provide images stably. It is another object of the present invention to provide a stirring member, a developing device, a process cartridge, and an image forming apparatus in consideration of downsizing and improvement in convenience.

In order to solve the above problems, the present invention has the following features.
The image forming apparatus according to the present invention is an image forming apparatus having at least a process cartridge integrally supporting an image carrier and a developing device, and an optical unit, wherein the developing device rotates with a stirring unit for stirring the developer. The stirring unit conveys the developer in a direction perpendicular to the rotation axis, and the radii of both end portions of the stirring unit formed in the rotation axis direction are set at the central part of the stirring unit. A stirring member that is smaller than the radius is provided, and the inner surface radius of the lower portion of the casing that houses the stirring member is made substantially equal to the radius of each of the both end portions and the central portion of the stirring portion, so that both end portions of the casing are made smaller. The process cartridge, the side plate of the image forming apparatus main body for guiding the attachment and detachment of the process cartridge, and the optical unit by reducing both ends of the casing A space is formed between the image forming apparatus and a vent hole communicating with the space is provided in the image forming apparatus, and an air passage is formed between the process cartridge and the image forming apparatus so as to generate an air flow. it characterized by cooling the inside of the apparatus.
By reducing both ends of the casing of the process cartridge in accordance with the reduction in both ends of the agitating member, a sufficient space is provided between both ends of the process cartridge and the image forming apparatus main body to form an air passage. In addition, it is possible to effectively dissipate heat while suppressing the temperature rise of the stirring unit and the process cartridge. Further, the deterioration of the developer is prevented, and the influence of the solidification of the toner and the rotating shaft of the stirring unit and the image due to the fixation of the toner can be prevented, so that a high-quality image can be stably provided. In addition, by reducing both ends of the stirring member, the effect of suppressing the temperature rise of the stirring unit can be exhibited without requiring complicated cooling means, and the convenience is improved without increasing the size of the image forming apparatus. Can be made.
Further, the optical unit is disposed close to the process cartridge to reduce unnecessary gaps, so that the space at the end of the process cartridge can exhibit an effect as an air path for cooling.
In the conventional machine, the vicinity of the side plate in the main body of the image forming apparatus is blocked by the process cartridge and the optical unit, and it is difficult for the air flow from the bottom to the top, but the main body of the image forming apparatus as in the present invention. Since there is a space in the inner side plate, an air flow is generated due to a change in the fluid density due to a temperature change (hereinafter referred to as “natural convection”), and the end of the process cartridge, in particular, the stirring portion of the developing portion. The edge can be cooled.

The image forming apparatus of the present invention is further characterized in that the vent is provided in the image forming apparatus so as to be positioned upstream and downstream of the air flow generated in the space.
Since air flows easily due to natural convection, the air in the image forming apparatus is easily circulated with outside air, and the cooling effect of the end of the process cartridge is promoted.
The image forming apparatus of the present invention further includes a plurality of the process cartridges, and the process cartridges are arranged so that the spaces are connected in series.
By arranging the process cartridges vertically, natural convection is likely to occur and cooling efficiency is improved. Even if a complicated cooling means is not required, the effect of suppressing the temperature rise of the stirring unit can be exhibited, so that the image forming apparatus can be downsized. In addition, the effect can be obtained even when the process cartridges are arranged not only vertically but also obliquely to some extent.
In the image forming apparatus of the present invention, an external air intake port and / or an exhaust port are further provided in the image forming device so as to be positioned upstream and downstream of the air flow generated in the space. It is characterized by.
Since air flows easily due to natural convection, the air in the image forming apparatus is easily circulated with outside air, and the cooling effect of the end of the process cartridge is promoted. If the frequency of use of the image forming apparatus is low, there is a cooling effect even if either the intake port or the exhaust port is provided.

The image forming apparatus of the present invention is further characterized in that either or both of an intake fan for taking in air from the outside and an exhaust fan for exhausting to the outside are provided between the intake port and the exhaust port. .
When the air flow is forcibly generated by the fan (hereinafter referred to as “forced convection”), the air in the image forming apparatus is more easily circulated with the outside air, and the end of the process cartridge is cooled more quickly. There is. If the frequency of use of the image forming apparatus is low, there is a cooling effect even if either the intake fan or the exhaust fan is provided. In the image forming apparatus of the present invention, the process cartridge further includes the optical unit. It is a process cartridge in which a casing shape is formed so that a space (hereinafter referred to as an optical path) for irradiating light from a unit and the space are connected.
By connecting the optical path and the space, an air flow can be generated around the photoconductor in the optical path, which is effective for cooling around the photoconductor. By cooling the periphery of the photoconductor, problems such as filming of the photoconductor can be solved. Further, in the optical path in the process cartridge, a minute amount of developer fine powder from the photosensitive member may stay in a small amount, but by connecting to the space, the fine powder can be prevented from staying.
In the image forming apparatus of the present invention, the optical unit further includes a cooling fan that sucks air from outside air into the optical unit and exhausts it from a window on the optical path, and the space connected to the optical path is used as an air path. The exhaust fan is configured to exhaust to the outside.
In general, a dust-proof glass is used at the exit of the optical path of the optical unit to prevent dust from the process cartridge and the surroundings from entering the optical unit. In the present invention, dust-proof glass is not required, and the cost can be greatly reduced by using the intake fan as a cooling fan attached to the optical unit. Further, by generating forced convection by the fan, the process cartridge can be efficiently cooled without requiring complicated cooling means, and the image forming apparatus can be downsized.

  By means for solving the above-mentioned problems, the present invention is able to effectively dissipate heat by suppressing temperature rises at the ends of the stirring member, the developing device and the process cartridge. In addition, the optical unit is disposed close to the process cartridge to reduce unnecessary gaps. Further, natural convection and forced convection are effectively generated, and the space at the end of the process cartridge serves as an air path for cooling. The effect was able to be demonstrated. Further, the deterioration of the developer was prevented, and the solidification of the toner and the influence of the rotating shaft of the stirring member and the image due to the fixation of the toner were prevented, and a high-quality image could be stably provided. Further, by reducing both ends of the agitation unit, the effect of suppressing the temperature increase of the agitation member can be exerted without requiring complicated cooling means, and the development device, the process cartridge, and the image forming apparatus can be reduced in size and convenience. It was possible to improve the performance.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to FIGS. However, these are merely embodiments and do not limit the scope of the claims of the present invention.

FIG. 1 is a schematic diagram illustrating the configuration of the image forming apparatus 1.
The image forming apparatus 1 includes an optical unit 1a, a paper feed roller 1b, a paper feed cassette 1c that stores recording paper 3, a transfer belt 1d, and a fixing roller 1e. The process cartridge 2 is attached to the image forming apparatus 1 in a detachable form. The recording paper 3 stored in the paper feed cassette 1c is conveyed to the photoreceptor 2d by the paper feed roller 1b. The visible image by the toner adhering to the photoreceptor 2d is transferred to the recording paper 3 by the transfer belt 1d. The recording paper 3 is fixed at the fixing nip portion and discharged to the outside of the image forming apparatus 1. The optical unit 1a includes a polygon motor, a polygon mirror, an Fθ lens, a laser diode, a mirror, and the like (not shown).

FIG. 2 is a cross-sectional view showing the configuration of the process cartridge 2.
The process cartridge 2 includes a photoreceptor 2d and at least one process means. The process means of this embodiment uses a charging roller 2a for charging the photosensitive member 2d, a toner storage portion 2b for developing, and a cleaning unit 2c for removing toner remaining on the surface of the photosensitive member 2d. ing. The photosensitive member 2d is rotated in the clockwise direction. At that time, the photosensitive member 2d is charged by the charging roller 2a and irradiated with a laser beam from the optical unit 1a to form an electrostatic latent image on the photosensitive member 2d. The electrostatic latent image is developed by a developing device.
The developing device is disposed as a developing means on the side of a cylindrical photosensitive member 2d that is an image carrier. A developing device as a casing 10 having an opening formed toward the photoreceptor 2d, a developing roller 5 having a built-in fixed magnet as a developer carrying member partially exposed from the opening, and carried on the developing roller 5. A developing blade 6 for adjusting the amount of the developer being conveyed, a toner storage portion 2b as a space for storing the developer, and the like. The developing means means that the developer in the toner container 8 is sent to the developing roller 5 side by the stirring member 9 via the toner supply port 8a, rotates the developing roller 5, and develops a specified amount frictionally charged by the developing blade 6. This means that a developer layer is formed on the surface of the developing roller 5, the developer is supplied to the developing area of the photoreceptor 2d, and the latent image is developed to form a toner image.
The toner storage portion 2b refers to a space between the toner supply port 8a and the developing roller 5 that are constituted by the casing upper portion 10a and the casing lower portion 10b. The toner storage portion 2b is a space for storing an appropriate amount of developer so that the developer sent from the developing roller 5 to the photosensitive member 2d can be appropriately replenished.
The developer is conveyed from the toner replenishing port 8a to the toner storage portion 2b. Even when the amount of the developer is reduced, the developer is conveyed toward the developing roller 5 by the left side inclination of the casing upper portion 10a and the developer's own weight. . A predetermined amount of developer is always taken in on the developing roller 5, and the toner density of the developer is always kept at a certain density or higher. Thus, since the toner density can be controlled within a substantially constant range, the toner density sensor, an optical image density sensor for detecting the image density of the reference toner image formed on the photoreceptor 2d in order to know the developing ability of the developer, A complicated toner density control mechanism using a toner replenishing member or the like becomes unnecessary.

  FIG. 3 is an embodiment of the process cartridge 2 in which both end portions of the casing 10 that accommodates the stirring member 9 are reduced in accordance with reduction in both end portions of the stirring portion. The inner surface radius of the casing lower portion 10b of the process cartridge 2 is made substantially equal to the respective radii of both end portions and the central portion of the stirring portion to form a space.

  FIG. 4 is a view showing the end shape of the process cartridge 2. The hatched portion is a cross-sectional view taken along the line B-B in FIG.

  FIG. 5 is a side view of the process cartridge of FIG. A surface that is one step lower than the longest surface of the process cartridge 2 is formed.

  FIG. 6 is a top view when a space is formed between the process cartridge 2 and the image forming apparatus 1 main body side plate. By forming a space around the developing member, particularly around the end of the stirring member, heat can be dissipated with respect to the heat generated in the bearing portion due to the rotation of the stirring member 9, and heat conduction to the main body of the image forming apparatus 1 is reduced. Can do.

  FIG. 7 is a top view when a space is formed between the process cartridge 2, the image forming apparatus 1 main body side plate, and the optical unit 1a. In FIG. 6, a space is simply formed between the process cartridge 2 and the image forming apparatus 1 main body side plate without considering the optical unit 1 a. However, if there are many gaps between the units around the process cartridge 2, the effect of the space formed as the air path cannot be sufficiently exhibited. This is because air flows in and out from other gaps, so that the space at the end of the process cartridge cannot function as an air path for cooling, and the function of suppressing the temperature rise at the end of the process cartridge is reduced. It is. In order to solve such a problem, the optical unit 1a is disposed close to the process cartridge so as not to create an unnecessary gap.

  FIG. 8 is an example of a monochrome machine in which the intake port 21 and the exhaust port 22 are installed on the same side plate of the main body of the image forming apparatus 1. The shielding plate 20 shields fixing heat and circulates air from the intake port 21 to the exhaust port 22 so as to smoothly flow as indicated by arrows. The air flow is promoted, and cooling in the process cartridge 2 and the image forming apparatus 1 main body is promoted.

  FIG. 9 is an example of a monochrome machine in which the intake port 21 and the exhaust port 22 are installed on opposite side plates of the main body of the image forming apparatus 1. In the conventional machine, the vicinity of the side plate in the main body of the image forming apparatus is blocked by the process cartridge and the optical unit, and it is difficult for the air flow from the bottom to the top, but the main body of the image forming apparatus as in the present invention. Since there is a space in the inner side plate, natural convection occurs, and the end of the process cartridge 2, in particular, the end of the stirring member of the developing unit can be cooled.

  FIG. 10 is an example of a tandem color machine showing an air path when a plurality of process cartridges 2 are vertically arranged. A gap S serving as an optical path from the optical unit 1a is provided between the process cartridges 2 so that the optical path and a space formed at the end of the process cartridge 2 are connected so that air flows smoothly. .

  FIG. 11 shows an example of a tandem color machine in which the intake port 21 and the exhaust port 22 are installed on the same side plate of the main body of the image forming apparatus 1. By arranging the process cartridge 2 vertically, an air flow is generated by natural convection from the bottom to the top, and the air flow can be easily made. Further, the effect can be obtained even when the process cartridge 2 is arranged not only vertically but also obliquely to some extent. Further, since there is a fixing device in the vicinity of the exit of the connection space of the process cartridge 2, a shielding plate 20 is arranged to block heat from the fixing device.

  FIG. 12 is a diagram showing the air flow in the example of the tandem color machine of FIG. By making the space at the end of the process cartridge 2 linear in this way, the air flow becomes smooth, and not only the stirring member end of the developing portion of the process cartridge 2 is cooled, but also the surrounding units and image formation The temperature rise inside the apparatus 1 body can be suppressed.

  FIG. 13 shows an example of a tandem color machine in which the intake fan 23 and the exhaust fan 24 are installed on the same side plate of the main body of the image forming apparatus 1. When forced convection is generated by the fan, the air in the image forming apparatus 1 is more easily circulated with the outside air, and the end of the process cartridge 2 is cooled more quickly. In addition, when the frequency of use of the image forming apparatus 1 is low, there is a cooling effect even if either the intake fan 23 or the exhaust fan 24 is provided. Therefore, the image forming apparatus 1 can be appropriately selected according to the specifications of the image forming apparatus 1. .

  FIG. 14 is a diagram illustrating the air flow in an example of a tandem color machine in which the intake port 21 and the exhaust fan 24 are installed on the same side plate of the main body of the image forming apparatus 1. Even if only the exhaust fan 24 is provided, the air in the image forming apparatus 1 is easily circulated with the outside air due to the occurrence of forced convection, so that there is a cooling effect.

  FIG. 15 is a diagram showing the air flow when the cooling fan 25 is attached to the lower part of the optical unit 1a of FIG. Air is sent into the optical unit 1a from the cooling fan 25 to cool the optical unit 1a. The air sent in is exhausted from a window on the optical path, and a space from the end of the process cartridge 2 connected to the optical path is used as an air path, and exhausted from the exhaust fan 24 to the outside. As a result, the temperature rise in the optical unit 1a, the developing unit of the process cartridge 2, the surrounding units, and the image forming apparatus 1 main body can be suppressed.

FIG. 16 is a diagram showing in detail the flow of air when the cooling fan 25 is attached to the lower part of the optical unit 1a. A cooling fan 25 for sucking outside air through a filter (not shown) is attached to the lower part of the optical unit 1a. The wind pressure discharged from the window on the optical path generated by the cooling fan 25 is P1, the negative pressure generated by the exhaust fan 24 is P2, and the wind pressure applied from the air path on the process cartridge side toward the window on the optical path of the optical unit 1a is P3. In this case, the dust from the optical path window of the optical unit 1a can be blocked by always setting P1> P3. This is because dust from the process cartridge 2 and the surroundings can be prevented from entering the optical unit 1a from the window on the optical path of the optical unit 1a by the reverse flow of air.
Normally, the dust in the outlet of the process cartridge 2 and the circumferential Rika et optical path of the optical portion 1a is using the dust-proof glass in order to prevent from entering the optical unit 1a. In the present invention, dust-proof glass is not required, and the intake fan 23 is also used as the cooling fan 25 attached to the optical unit 1a, so that a significant cost reduction can be achieved. Further, by generating forced convection by the fan, the process cartridge 2 can be efficiently cooled without requiring complicated cooling means, and the image forming apparatus 1 can be downsized.

1 is a diagram illustrating a configuration of an image forming apparatus. It is sectional drawing which showed the structure of the process cartridge. It is one Embodiment figure of the process cartridge which made the both ends of the casing which accommodates a stirring member small according to having made the both ends of the stirring part small. FIG. 4 is a diagram illustrating an end shape of a process cartridge. FIG. 5 is a side view of the process cartridge of FIG. 4 as viewed from an arrow A. FIG. 6 is a top view when a space is formed between the process cartridge and the image forming apparatus main body side plate. FIG. 3 is a top view when a space is formed between a process cartridge, an image forming apparatus main body side plate, and an optical unit. This is an example of a monochrome machine in which an intake port and an exhaust port are installed on the same side plate of the image forming apparatus main body. This is an example of a monochrome machine in which an intake port and an exhaust port are installed on opposing side plates of the image forming apparatus main body. It is an example of a tandem color machine showing an air path when a plurality of process cartridges are arranged vertically. This is an example of a tandem color machine in which an intake port and an exhaust port are installed on the same side plate of the image forming apparatus main body. It is a figure showing the flow of the air in the example of the tandem color machine of FIG. This is an example of a tandem color machine in which an intake fan and an exhaust fan are installed on the same side plate of the image forming apparatus main body. It is a figure showing the flow of the air in the example of the tandem color machine which installed the intake port and the exhaust fan on the same side plate of the image forming apparatus main body. It is a figure showing the flow of air when a cooling fan is attached to the lower part of the optical part of FIG. It is the figure which represented in detail the flow of the air when a cooling fan was attached to the lower part of an optical part.

DESCRIPTION OF SYMBOLS 1 Image forming apparatus 1a Optical part 1b Paper feed roller 1c Paper feed cassette 1d Transfer belt 1e Fixing roller 2 Process cartridge 2a Charging roller 2b Toner storage part 2c Cleaning part 2d Photoconductor 3 Recording paper 5 Developing roller 6 Developing blade 8 Toner container 8a Toner supply port 9 Stirring member 10 Casing 10a Casing upper part 10b Casing lower part 20 Blocking plate 21 Intake port 22 Exhaust port 23 Intake fan 24 Exhaust fan 25 Cooling fan

Claims (7)

A process cartridge that integrally supports at least the image carrier and the developing device;
In an image forming apparatus having an optical unit,
The developing device includes a stirrer for stirring the developer and a shaft serving as a rotation center, and the stirrer transports the developer in a direction perpendicular to the rotation axis, and the stirrer formed in the rotation axis direction. A stirring member in which the radius of both end portions is smaller than the radius of the central portion of the stirring portion,
The inner radius of the lower portion of the casing that houses the stirring member is substantially equal to the radius of each of the both end portions and the central portion of the stirring portion, and both end portions of the casing are made small,
By reducing both ends of the casing, a space is formed between the process cartridge, the side plate of the image forming apparatus main body for guiding the attachment and detachment of the process cartridge, and the optical unit,
Providing an air vent in the image forming apparatus to communicate with the space, forming an air path so that an air flow is generated between the process cartridge and the image forming apparatus, and cooling the inside of the process cartridge and the image forming apparatus. An image forming apparatus. The image forming apparatus according to claim 1, wherein the vent is provided in the image forming apparatus so as to be positioned on an upstream side and a downstream side of an air flow generated in the space. The image forming apparatus according to claim 1, wherein a plurality of the process cartridges are provided, and the process cartridges are arranged so that the spaces are connected in series. 4. The image forming apparatus according to claim 1, wherein one or both of an external air intake port and an air exhaust port are provided in the image forming apparatus so as to be positioned upstream and downstream of the air flow generated in the space. The image forming apparatus according to any one of the above. The image forming apparatus according to claim 4 , wherein one or both of an intake fan that takes in air from the outside and an exhaust fan that exhausts the air to the outside are provided between the intake port and the exhaust port. 6. The process cartridge according to claim 1, wherein the process cartridge is a process cartridge having a casing shape so that a space for irradiating light from the optical unit and the space are connected to each other. Image forming apparatus. The optical unit has a cooling fan that sucks air from outside air into the optical unit, and exhausts air from a window on the optical path, and exhausts air from the exhaust fan using the space connected to the optical path as an air path. The image forming apparatus according to claim 5, wherein the image forming apparatus is an image forming apparatus.

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