Image forming apparatus

A development device that has communication port sealing means for sealing a communication port communicating a developer supporter container with a developer container. The development device is advantageous in cost reduction, easy manufacturing, and formation of high-quality images. In the development device which has a developing roller container for containing a developing roller, a developer container for containing a developer, a base member for forming a communication port communicating the developer roller container with the developer container, and a seal member that is adhered to the base member so as to cover the communication port, and which cancels sealing of the communication port by peeling off the seal member from the base member by pulling out the seal member in a direction parallel to an opened surface of the communication port, the base member is composed of a polypropylene resin having a bent section, and the seal member is adhered to the base member by thermal compression bonding.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an image forming apparatus such as a copying machine, facsimile apparatus, printer or the like, and more particularly to a development device used in such image forming apparatus, as well as a process cartridge using the development device.

2. Description of the Background Art

As a development device that is used in this type of image forming apparatus, there has conventionally be known a development device that has a developer supporter container, a developer container for storing the developer, a communication port communicating the developer supporter container with the developer container, and communication port sealing means for sealing the communication port. By providing the communication port sealing means in the development device, the developer can be prevented from leaking and dispersing from an opening section of the developer supporter container when carrying the development device alone. Also, since the developer is separated from the external air, deterioration of the developer that is caused when the developer contacts with the air can be prevented.

For example, Japanese Unexamined Patent Application Publication No. 2006-23619 discloses a development device that is provided with the communication port sealing means having a frame body for forming the communication port, and a seal member adhered to the frame body so as to cover the communication port. In this development device, the seal member adhered to the frame body of the communication port sealing means is peeled off when starting to use the development device, whereby the development supporter container and the developer container can be communicated with each other, and the developer can be supplied to the developer supporter container.

However, this conventional developer apparatus had to be designed such that the sheet thickness of the frame body of the communication port sealing means had to be thick in order to ensure the strength thereof for peeling off the seal member, or a bent section had to be provided on an end section of the frame body. In the case in which a PET resin (polyethylene terephthalate resin) is used as the material of the frame body, thickening the sheet thickness leads to increase of the cost. Moreover, when providing the bent section by means of a thick PET resin material, cracks and scuffing are formed on the bent section due to its hardness, causing poor mold formability. Furthermore, the seal member formed from a PET film into a two-sided tape was generally adhered to the frame body composed of the PET resin. However, when pulling out the seal member the two-sided tape that is nearly peeling off abuts on the developer supporter, whereby a developer layer on the developer supporter is sometimes damaged, or the completely peeled two-sided tape enters the developer supporter container, resulting in a defective image with white stripes and the like. Therefore, there was a problem that the use of such two-sided tape to adhere the seal member is not enough to obtain a high-quality image.

Technologies relating to the present invention are also disclosed in, e.g., Japanese Patent Application No. 3402872.

SUMMARY OF THE INVENTION

The present invention is contrived in view of the background described above, and an object thereof is to provide a development device that has communication port sealing means for sealing a communication port communicating a developer supporter container with a developer container, and that is capable of realizing cost reduction, easy manufacturing and formation of high-quality images, a process cartridge having this development device, and an image forming apparatus having either one of the above devices.

In an aspect of the present invention, there is provided a development device which comprises a developer supporter container for containing a developer supporter; a developer container for containing a developer supplied to the developer supporter; a frame body for forming a communication port that communicates the developer supporter container with the developer container; and a seal member that is adhered to the frame body so as to cover the communication port. Sealing of the communication port is canceled by peeling off the seal member from the frame body by pulling out the seal member in a direction parallel to an opened surface of the communication port. The frame body is composed of a polypropylene resin having a bent section, and the seal member is adhered to the frame body by thermal compression bonding.

In another aspect of the present invention, there is provided a process cartridge in which at least a latent image supporter and a development device for developing a latent image on the latent image supporter are integrally supported, and which is configured detachably with respect to an image forming apparatus main body. The development device comprises: a developer supporter container for containing a developer supporter; a developer container for containing a developer supplied to the developer supporter; a frame body for forming a communication port that communicates the developer supporter container with the developer container; and a seal member that is adhered to the frame body so as to cover the communication port. Sealing of the communication port is canceled by peeling off the seal member from the frame body by pulling out the seal member in a direction parallel to an opened surface of the communication port. The frame body is composed of a polypropylene resin having a bent section, and the seal member is adhered to the frame body by thermal compression bonding.

In another aspect of the present invention, there is provided an image forming apparatus which comprises a charging device for charging a surface of a latent image supporter; a latent image forming device for forming an electrostatic latent image on the latent image supporter; and a development device for developing the electrostatic latent image to form a toner image. The development device comprises: a developer supporter container for containing a developer supporter; a developer container for containing a developer supplied to the developer supporter; a frame body for forming a communication port that communicates the developer supporter container with the developer container; and a seal member that is adhered to the frame body so as to cover the communication port. Sealing of the communication port is canceled by peeling off the seal member from the frame body by pulling out the seal member in a direction parallel to an opened surface of the communication port. The frame body is composed of a polypropylene resin having a bent section, and the seal member is adhered to the frame body by thermal compression bonding.

In another aspect of the present invention, there is provided a color image forming apparatus which comprises a charging device for charging a surface of a latent image supporter; a latent image forming device for forming an electrostatic latent image on the latent image supporter; and a plurality of development devices for developing the electrostatic latent image to form a toner image. Each of the development devices comprises: developer supporter container for containing a developer supporter; a developer container for containing a developer supplied to the developer supporter; a frame body for forming a communication port that communicates the developer supporter container with the developer container; and a seal member that is adhered to the frame body so as to cover the communication port. Sealing of the communication port is canceled by peeling off the seal member from the frame body by pulling out the seal member in a direction parallel to an opened surface of the communication port. The frame body is composed of a polypropylene resin having a bent section, and the seal member is adhered to the frame body by thermal compression bonding.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, an electrophotographic printer (simply referred to as “printer100” hereinafter) is described as an embodiment of the image forming apparatus to which the present invention is applied. It should be noted that an image formation section is described as the process cartridge.

First of all, the basic configuration of the printer100is described.

FIG. 1shows a schematic configuration of the printer100. In the figure, the printer100has four process cartridges6Y, M, C and K for generating toner images in colors of yellow, magenta, cyan and black (marked as “Y,” “M,” “C” and “K” hereinafter) respectively. These process cartridges respectively use Y, M, C and K toners in different colors as image forming substances, but other configurations thereof are the same, and these process cartridges are replaced at the end of their lives. For example, the process cartridge6Y for generating a Y toner image has, as shown inFIG. 2, a photoreceptor1Y as a drum-like image supporter, a drum cleaning device2Y, an electricity removing device (not shown), a charging device4Y, a development device5Y, and the like. This process cartridge6Y is detachable with respect to the printer100main body, and wear-out parts thereof can be removed at once.

The charging device4Y charges, uniformly, the surface of the photoreceptor that is rotated clockwise shown in the figure by driving means which is not shown. The surface of the photoreceptor1Y, which is charged uniformly, is subjected to exposure scanning by laser beam L and then supports a Y electrostatic latent image. This Y electrostatic latent image is developed into a Y toner image by the development device5Y that uses a Y toner. Then, the toner image formed on the photoreceptor1Y is intermediately transferred onto an intermediate transfer roller8. The drum cleaning device2Y removes toner obtained after the intermediate transfer step and thereby remaining on the surface of the photoreceptor1Y.

Moreover, the electricity removing device removes the residual electric charge of the cleaned photoreceptor1Y. By this electricity removal, the surface of the photoreceptor1Y is initialized to prepare for the next image formation. For the other process cartridges6M, C and K as well, M, C and K toner images are formed on photoreceptors1M, C and K similarly and then intermediately transferred onto an intermediate transfer belt8.

An exposure device7is disposed in a lower section of the process cartridges6Y, M, C and K that are previously shownFIG. 1. The exposure device7, which is latent image forming means, irradiates and exposes the photoreceptor of each of the process cartridges6Y, M, C and K with the laser beam L. By this exposure, Y, M, C and K electrostatic latent images are formed on the photoreceptors1Y, M, C and K respectively. It should be noted that the exposure device7irradiates the photoreceptors by means of a plurality of optical lenses or mirrors, while using a polygon mirror, which is rotary drive by a motor, to scan the laser beam L generated from a light source.

On the lower side of the exposure device7shown in the figure, there is disposed paper feeding means that has a paper containing cassette26, a feed roller27incorporated therein, a pair of resist rollers28and the like.

The paper containing cassette26contains a plurality of stacked transfer papers P which are recording bodies, and the feed roller27is in contact with the top transfer paper P. Once the feed roller27is rotated in a counterclockwise direction shown in the figure by the unshown driving means, the top transfer paper P is fed toward between the pair of resist rollers28.

The pair of resist rollers28are rotary driven so as to slip the transfer paper P therebetween, but stop rotating once the paper is slipped therebetween. Then, the pair of resist rollers28sends the transfer paper P toward a secondary transfer nip, which is described hereinafter, at an appropriate time. In the paper feeding means having such a configuration, the combination of the feed roller27and the pair of resist rollers28, which are timing rollers, configure convening means. This conveying means is for conveying the transfer papers P from the paper containing cassette26, which is containing means, to the secondary transfer nip described hereinafter.

In an upper section of the process cartridges6Y, M, C and K shown in the figure, there is disposed an intermediate transfer unit15for endlessly moving the intermediate transfer belt8, which is an intermediate transfer body, while winding the intermediate transfer belt8. This intermediate transfer unit15has not only the intermediate transfer belt8but also four primary transfer bias rollers9Y, M, C and K, and a belt cleaning device10. The intermediate transfer unit15further has a secondary transfer backup roller12, a cleaning backup roller13, and a tension roller14.

The intermediate transfer belt8is wrapped around these three rollers and at the same time endlessly moved in the counterclockwise direction shown in the figure by the rotary drive of at least one of these rollers. The primary transfer bias rollers9Y, M, C and K each holds the intermediate transfer belt8with each of the photoreceptors1Y, M, C and K, the intermediate transfer belt being endlessly moved in the above manner, whereby a primary transfer nip is formed therebetween. Such formation of the primary transfer nips is a way to apply, to the back of the intermediate transfer belt8(inner periphery of the loop), a transfer bias having a polarity opposite to that of the toner.

The rollers besides the primary transfer bias rollers9Y, M, C and K are all electrically connected to ground. During the process in which the intermediate transfer belt8sequentially passes through the Y, M, C and K primary transfer nips as the intermediate transfer belt8is moved endlessly moved, the Y, M, C and K toner images on the respective photoreceptors1Y, M, C and K are superimposed sequentially and then primarily transferred. Accordingly, a toner image with four superimposed colors (referred to as “four-color toner image” hereinafter) is formed on the intermediate transfer belt8.

The secondary transfer backup roller12and a secondary transfer roller19hold the intermediate transfer belt8therebetween to form a secondary transfer nip. The four-color toner image formed on the intermediate transfer belt8is transferred onto the transfer paper P at this secondary transfer nip. Transferred residual toner, which was not transferred onto the transfer paper P, remains on the intermediate transfer belt8that has passed through the secondary transfer nip. Such toner is cleaned off by the belt cleaning device10.

At the secondary transfer nip, the transfer paper P is held between the intermediate transfer belt8and the secondary transfer roller19that move on the surface of each other in forward directions thereof, and then conveyed in the opposite direction from the pair of resist rollers28. When the transfer paper P that is sent out from the secondary transfer nip passes through between rollers of a fixing device20, the four-color toner image that has been transferred on the surface is fixed to the transfer paper P by heat and pressure. Thereafter, the transfer paper P is ejected to the outside of the machine through a pair of paper ejection rollers29. A stack section30is formed on an upper surface of the printer main body, and the transfer papers P that are ejected to the outside of the machine by the pair of paper ejection rollers29are stacked sequentially on this stack section30.

Furthermore, a bottle container31is disposed on the lower side of this stack section30. This bottle container31contains toner bottles32Y, M, C and K that are developer containers for containing the Y, M, C and K toners. The toner bottles32Y, M, C and K are arranged downward for the respective toner colors on the bottle container31. The Y, M, C and K toners inside the respective toner bottles32Y, M, C and K are replenished appropriately to the development devices of the process cartridges6Y, M, C and K respectively via a toner replenishing device, which is not shown.

Next, a configuration of the development device5Y within the process cartridge6Y is described usingFIG. 2.

The development device5Y has magnetic field generating means on the inside thereof, and a developing roller51Y, which is a developer supporter that supports on the surface thereof a binary developer composed of a toner and a carrier and conveys the binary developer, is provided in a developing roller container53Y, which is a developer supporter container. Furthermore, the developing roller51Y is partially exposed from an opening section of a casing that forms the developing roller container53Y, and forms a developing area in cooperation with the photoreceptor1Y. Moreover, a developing doctor52Y, which is a developer controlling member for controlling the thickness of a layer of developer, is provided on an upstream side in a direction of the surface movement of the developing roller51Y from the developing area.

A developer container54Y for containing the developer is provided on the lower side of the developing roller container53Y, and there is also provided a communication port59Y for communicating the developer roller container53Y with a toner replenishing port58Y that delivers the toner into the developer container54Y. Moreover, the developer container54Y is partitioned with a partition wall77Y into a first developer container54Ya on the developing roller51Y side and a second developer container54Yb on the toner replenishing port58Y side. The first developer container54Ya and the second developer container54Yb each has a toner conveying screw (conveying body) for stirring and conveying the toner: a first conveying screw55Ya; and a second conveying screw55Yb. In an upper section of the toner replenishing port58Y, there are provided a shutter71Y for closing the toner replenishing port58Y, and a toner replenishing port case72Y that supports the shutter71Y and covers the toner replenishing port58Y.

The development device5Y contains the toner and carrier as the developer in advance, and toner that is consumed through development is replenished from the toner bottle32Y which is the toner container shown inFIG. 1, and, in response to this replenishment, is contained in the development device5Y.

Here, a reference numeral56Y indicates a density detecting sensor for detecting the toner density in the developer. Once this density detecting sensor56Y detects insufficiency of the toner density within the developer container54Y, a drive motor41Y is rotated by transmission of a replenishment signal from a controller57Y, and the toner bottle32Y is rotated, whereby the toner is replenished.

In addition, the development device5Y is formed large by an upper case75Y having an internal wall of the developing roller container53Y and a lower case76Y having an internal wall of the developer container54Y.

The operation of the development device5Y is described next.

The toner that is replenished from the toner bottle32Y into the development device5Y is replenished from the toner replenishing port58Y into the second developer container54Yb of the developer container54Y. The toner that is replenished into the second developer container54Yb of the development device5Y is stirred with the carrier by the second conveying screw55Yb. The developer within the second developer container54Yb that is composed of the toner and carrier is conveyed in an axial direction while being stirred by the second conveying screw55Yb. The developer that was conveyed by the second conveying screw55Yb and has reached an end section of the second developer container54Yb passes through an opening section at an end section of the partition wall77Y, and moves toward the first developer container54Ya. The developer within the first developer container54Ya is conveyed in the opposite direction from the developer within the second developer container54Yb while being stirred by the first conveying screw55Ya. Once the developer reaches an end section of the first developer container54Ya, the developer passes through the opening section at the end section of the partition wall77Y and moves toward the second developer container54Yb.

In this manner, the developers are caused to circulate within the developer container54Y by the first conveying screw55Ya and the second conveying screw55Yb.

Of the developer that is stirred and conveyed by the first conveying screw55Ya in the first developer container54Ya, developer that is drawn to the developing roller51Y passes through the communication port59Y, which is described hereinafter, and is then supported on the developing roller51Y. The carrier within this developer is drawn to the developing roller51Y by the magnetic force of a magnetic roller provided within the developing roller51Y, and is then supported on the developing roller51Y. The toner within this developer is stirred and thereby charged to a polarity opposite that of the carrier. Since electrostatic force is applied between the toner and carrier, the toner and the carrier are supported on the developing roller51Y. The developer supported on the developing roller51Y passes through a space between the developing doctor52Y and the surface of the developing roller51Y (doctor gap), whereby the thickness of the developer layer is controlled. Once the developer with controlled thickness is conveyed to the developing area facing the photoreceptor1Y, the developer forms a magnetic brush on the developing roller51Y due to the magnetic force of the magnetic roller.

Here, the surface of the developing roller51Y moves in the developing area in the same direction as, and at a linear speed faster than, the surface of the photoreceptor1Y. The carrier forming a magnetic brush on the developing roller51Y supplies toner adhered to the carrier surface to the surface of the photoreceptor1Y, while sliding on the surface of the photoreceptor1Y. At this moment, a developing bias is applied from an unshown power source to the developing roller51Y, whereby a development field is formed in the developing area. Between the electrostatic latent image on the photoreceptor1Y and the developing roller51Y, electrostatic force that is pulled toward the electrostatic latent image acts on the toner located on the developing roller51Y. Accordingly, the toner on the developing roller51Y adheres to the electrostatic latent image on the photoreceptor1Y. By this adhesion, the electrostatic latent image on the photoreceptor1Y is developed into a toner image of a corresponding color.

The communication port59Y and communication port sealing means which are the characteristics of the present embodiment are described next.

The development device5Y of the present embodiment is provided with the communication port59Y for communicating the developing roller container53Y with the first developer container54Y, and a communication port sealing member80Y that seals the communication port59Y. By providing such a communication port sealing member80Y, the developer can be prevented from leaking from an opening section of the developing roller container53Y and dispersing when carrying the process cartridge6Y alone. Moreover, the developer is separated from the external air, thus developer deterioration that is caused when the developer contacts with the air can be prevented from occurring.

FIG. 3shows a schematic configuration of the communication port sealing member80Y. The communication port sealing member80Y has a base member81Y, which is a frame body forming an opening as the communication port59Y, and a seal member82Y, which is directly thermal compression bonded to the base member81Y so as to cover the opening.

As shown inFIG. 3, an end section of the seal member82Y protrudes as a pulling section from an end section of the base ember81Y to the outside so that the seal member82Y can be pulled out. By pulling out the pulling section of the seal member82Y in a direction to the right parallel to the opened surface, the seal member82Y that is thermal compression bonded to the base member81Y is peeled off, whereby the opening formed on the base member81Y appears, and the communication port59Y communicating the first developer container54Ya with the developing roller container53Y is formed. Accordingly, the developer can be supplied from the first developer container54Ya to the developing roller container53Y through the communication port59Y.

Further, the base member81Y has a bent section83Y, which is formed by bending a base member end section that is positioned in a direction lateral to the direction of pulling out the seal member82Y. By providing such bent section83Y, the strength of the force of pulling out the seal member82Y in a direction parallel to the opened surface and thereby peeling off the seal member82Y from the base member81Y can be enhanced.

A resin material that is strong in bending, such as polypropylene (PP), is used as the material of the base member81Y. The reason that a polypropylene (PP) material is used is because the formability thereof is better than that of a PET resin, and because this material is stable since cracks and scuffing are not generated even on a thick polypropylene material. In the case where cracks are generated, dusts (scums) and other foreign matters on, for example, the cracked parts can enter the developer, resulting in a defective image with white stripes and the like.

Moreover, regarding the thickness of the material, the material having a thickness of 0.8 mm or less is used. By providing the bent section83Y in the base member81Y, the material having such thickness can have sufficient strength, compared to a flat plate. In addition, use of the polypropylene (PP) resin is less expensive compared to use of a PET resin.

For the seal member82Y, an easy-peel film (manufactured by Sun A Kaken Co., Ltd.) is used. The easy-peel film is a film with a four-layered structure having PET as a base material and constituted from PET25 μm/ONY/15 μm, PEF/30 μm, and KB/40 μm. The seal member82Y constituted from this easy-peel film is directly thermal compression bonded to the polypropylene base member81Y without using a two-sided tape, thus the two-sided tape can be prevented from abutting on the developing roller51Y when the seal member82Y is peeled off, or from entering the developing roller container53Y, whereby the occurrence of defective images can be inhibited. Furthermore, compared to the production process having two steps where the two-sided tape is attached first and then the seal member is attached, this embodiment has only one step of directly thermal compression bonding the sealing member, thus the communication port sealing member can be produced easily.

Next, a method of installing the communication port sealing member80Y is described with reference toFIG. 4AthroughFIG. 4C.

First, the communication port sealing member80Y is brought close to the lower case76Y (FIG. 4A). The bent section83Y of the communication port sealing member80Y is hooked to the partition wall77Y of the lower case76Y to bring the other side of the bent section83Y gradually close to a flat surface section78Y of the lower case76Y (FIG. 4B). The bent section83Y is hooked to the partition wall77Y, the other side of the bent section83Y is placed on the flat surface section78Y of the lower case76Y, and then the communication port sealing member is set so as to abut on a wall standing on the flat surface section78Y (FIG. 4C).

After setting the communication port sealing member80Y in this manner, the upper case75Y is set, and the communication port sealing member80Y is installed so as to be held between the upper case75Y and the lower case76Y. It should be noted that the communication port sealing member80Y may be attached to the flat surface section78Y of the lower case76Y, whereby the communication port sealing member80Y can be fitted stably. By providing the bent section83Y in the base member81Y in this manner, the setting properties can be improved.

Furthermore,FIG. 5AthroughFIG. 5Cshow a state in which the communication port sealing member80Y is set into the lower case76Y. Specifically,FIG. 5Ashows the lower case76Y and the toner conveying screws55Ya and55Yb in a state in which the communication port sealing member80Y is not yet set,FIG. 5Bshows a state in which the communication port sealing member80Y is set into the lower case76Y, andFIG. 5Cshows a state in which the communication port sealing member80Y is set into the lower case76Y, and then the developing roller51Y is set.

It should be noted that in the development device5Y of the present embodiment, the binary developer composed of a toner and a carrier is used, but a single component developer without a carrier may be used.

It should also be noted that the above embodiment describes the configuration in which the process cartridges6Y, M, C and K that respectively have the development devices5Y, M, C and K and the photoreceptors1Y, M, C and K can be detached from and attached to the printer100, but the present invention is not limited to this embodiment. The process cartridges may have at least the development devices5Y, M, C and K, and only the development devices may be detachable with respect to the apparatus main body. The present invention can be applied to such development devices5Y, M, C and K, and the same effects can be obtained. Moreover, the invention can also be applied to the image forming apparatus which uses the development devices5Y, M, C and K or the process cartridges6Y, M, C and K in which the above-described invention is implemented and, and still the same effects can be obtained.

As described above, according to the printer of the present embodiment, the base member81Y is composed of a polypropylene resin, thus the formability thereof is better than when using a PET resin, and the bent section can be provided even in a thick base member. Therefore, a communication port sealing member that has stronger force of pulling out the seal member82Y can be produced easily. In addition, since the base member is composed of the polypropylene resin, the communication port sealing member can be obtained inexpensively, compared to the case where a PET resin is used. Further, the seal member82Y is directly thermal compression bonded to the polypropylene base member81Y without using a two-sided tape, thus the occurrence of a defective image caused by a two-sided tape when peeling off the seal member82Y can be prevented. Also, there is only one manufacturing step of directly thermal compression bonding the seal member, thus the communication port sealing member can be produced easily.

The bent section83Y of the communication port sealing member80Y is hooked to the partition wall77Y of the developer container74Y to install the communication port sealing member80Y, whereby the setting properties can be improved.

Furthermore, the communication port sealing member80Y is installed so as to be held between the upper case75Y forming the developer roller container73Y and the lower case76Y forming the developer container74Y, whereby the communication port sealing member80Y can be stably supported.

Furthermore, after the communication port sealing member80Y is attached to the lower case76Y, the upper case75Y is placed on the communication port sealing member80Y so that the upper case75Y and the lower case76Y support the communication port sealing member80Y therebetween, whereby the communication port sealing member80Y can be supported more stably.

Moreover, the thickness of the base member81is set to 0.8 mm or less so that a light and inexpensive base member can be realized.

In addition, by configuring the process cartridge in which the photoreceptor1Y and the development device5Y are supported integrally, and which is detached from and attached to the image forming apparatus main body, the maintenance properties can be improved.

The above has described an embodiment of the present invention. However, according to the present invention, the development device, which has the communication port sealing means for sealing the communication port communicating the developer supporter container with the developer container, has the excellent effects, such cost reduction, easy manufacturing and formation of high-quality images.