Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2002-09-13
2004-06-15
Royer, William J. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C399S113000
Reexamination Certificate
active
06751428
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image forming device, such as a laser beam printer, a copying machine, or a facsimile device. More particularly, the invention relates to a process unit detachably loaded into the image forming device and a structure of the image forming device for receiving and accommodating the process unit.
2. Description of the Related Art
Conventional image forming devices, such as a laser beam printer, uses a process unit. The process unit is, for example, a combined unit of a photosensitive unit and a developing unit. The photosensitive unit includes a photosensitive drum and a charger. The developing unit includes a developing roller and a toner cartridge containing developing agent (toner) therein.
During the printing operation, the developing roller is urged against the photosensitive drum, so that the developing roller transfers toner onto the photosensitive drum. Also, the transfer roller is urged against the photosensitive drum.
For the sake of maintenance and for facilitating paper jam resolving job, the process unit is detachably mounted on the image forming device. That is, the process unit is unloaded from and loaded into the image forming device when paper jam occurs, for example.
U.S. Pat. No. 6,101,350 proposes horizontally loading the process unit. The horizontally loading type requires a locking mechanism to prevent the loaded process unit from being accidentally detached. To withstand strong detaching force to be imparted upon the process unit, a rigid locking mechanism is needed. However, the image forming device cannot be structurally simplified and made compact in size and also the cost of the image forming device cannot be lowered if the rigid locking mechanism is employed.
SUMMARY OF THE INVENTION
The present intention has been made to solve the aforementioned problems, and accordingly it is an object of the invention to provide an image forming device and a process unit in which the process unit can be easily loaded into the image forming unit and the process unit thus loaded cannot be easily detached.
Another object of the invention is to provide a process unit in which a developing unit can be easily mounted on and dismounted from a photosensitive unit.
Still another object of the invention is to provide an image forming device that has a simple structure for receiving a process unit and urging the developing roller against the photosensitive drum once the process unit is received and accommodated in a process unit accommodating section.
To achieve the above and other objects, there is provided, according to one aspect of the invention, an image forming device that includes a housing, a pair of first guides, a process unit, a process unit accommodating section, and a second guide. The first guides extend down to terminals. The process unit has a bottom wall and side walls. The side walls are formed with protrusions protruding outward. The protrusions are engageable with the first guides, and guided down along the first guides toward the terminals when the process unit is loaded into the housing. The process unit accommodating section is provided for receiving and accommodating the process unit. The second guide is formed between the first guides for guiding the bottom surface of the process unit from a top open space of the housing toward the terminal. The process unit is accommodated in the process unit accommodating section when the protrusions of the process unit have brought into abutment with the terminals and a trailing end of the process unit is rotated downward about an imaginary line connecting the protrusions.
With the image forming device thus constructed, the process unit can be easily accommodated in the process unit accommodating section. This can be done by engaging the protrusions with the first guide and placing the process unit on the second guide. When the protrusions formed in the process unit are brought into abutment with the terminals, the trailing end of the process unit is automatically rotated downward due to its own weight and accommodated into the accommodating section. Also, the process unit can be easily unloaded from image forming device by lifting the trailing end of the process unit, placing it on the second guide, and moving up along the second guide.
A posture maintaining member may be formed on the process unit for maintaining a posture of the process unit when accommodated in the process unit accommodating section.
Preferably, the first guide is in the form of an elongated U-shaped groove into which the protrusion is inserted, and the second guide is in the form of a rail having an upper flat surface on which the process unit slidably moves.
A locking mechanism may further be provided for locking the process unit to the housing. It is desirable that the locking mechanism be provided in the process unit accommodating section. The locking mechanism may be constructed to resiliently engage the trailing end of the process unit.
The process unit includes a photosensitive unit and a developing unit. The developing unit is detachably mounted on the photosensitive unit. The photosensitive unit includes a photosensitive drum, and the developing unit includes a developing roller. The protrusions are provided to the photosensitive unit. The rotational shaft of the photosensitive drum may be provided to project from the photosensitive unit. In such a case, the projected portions of the rotational shaft may be used as the protrusions.
A latching mechanism may be further provided for latching the process unit to the process unit accommodating section.
The process unit includes a photosensitive drum and developing roller. It is desirable that the process unit is accommodated in the process unit accommodating section while being urged toward a predetermined direction to urge the developing roller against the photosensitive drum.
The process unit may be formed with auxiliary guide members for determining a loading direction and unloading direction of the process unit when loading into and unloading from the housing.
It is desirable that the developing unit have a bottom surface on which a first posture maintaining member is formed for maintaining a posture of the developing unit when mounted on the photosensitive unit and that the photosensitive unit have a bottom surface on which a second posture maintaining member is formed for maintaining a posture of the photosensitive unit when accommodated in the process unit accommodating section. Preferably, the first posture maintaining member and the second posture maintaining member are mated with each other.
According to another aspect of the invention, there is provided an image forming device that includes a housing, a process unit, a process unit accommodating section, and developing roller moving mechanism. The housing has a pair of upstanding walls each formed with a first guide extending to a first terminal. The process unit is detachably mounted on the housing. The process unit includes a photosensitive unit and a developing unit. The photosensitive unit has at least a photosensitive drum and first projections. The first projections are engageable with the first guides. The first protrusions are guided down along the first guides toward the first terminals when the process unit is loaded into the housing. The developing unit has at least a developing roller. The process unit accommodating section is provided for receiving and accommodating the process unit. The process unit is accommodated therein when a trailing end of the process unit is rotated downwardly about an imaginary line connecting the protrusions that are located in the first terminals. The developing roller moving mechanism is provided for moving the developing roller toward the photosensitive drum. At this time, the developing roller is urged against the photosensitive drum.
With the image forming device thus constructed, when the developing roller is urged against the photosensitive drum by the developing roller movin
Brother Kogyo Kabushiki Kaisha
Royer William J.
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