Electrophotography – Having particular structure – Modular or displaceable
Reexamination Certificate
2000-02-02
2001-04-17
Lee, Susan S. Y. (Department: 2852)
Electrophotography
Having particular structure
Modular or displaceable
C347S116000, C399S301000
Reexamination Certificate
active
06219508
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus, including a plurality of printing assemblies arranged in series, intended to make a multicolor record.
2. Description of the Related Art
The image forming apparatus of the electrostatic recording type comprises a photosensitive body (photosensitive drum), a charger,. an optical head for forming an electrostatic latent image on the photosensitive body, a developing device for developing the electrostatic latent image into a toner image, and a transfer element (transfer roller) for transferring the toner image onto paper. The charger, the optical head, the developing device and the transfer element are arranged to surround the photosensitive body to form a charged toner image while the photosensitive body rotates one revolution. The charged toner image is transferred from the photosensitive body onto paper by a transfer element, and the paper is then sent to a fixing device and is discharged.
The photosensitive body, the charger, the optical head, the developing device and the transfer element constitute a printing assembly. The image forming apparatus capable of making a multi-color record comprises a plurality of printing assemblies each including a photosensitive body, a charger, an optical head, a developing device and a transfer element. When, for example, developing agents of four colors, i.e., yellow, magenta, cyan and black are to be used, the image forming apparatus is equipped with four printing assemblies containing respective developing agents. The image forming apparatus of the tandem type in which a plurality of printing assemblies are arranged in series, is particularly effective in executing printing at high speed.
The paper is conveyed through the plurality of printing assemblies arranged in series, and a fixing device arranged after the assemblies, by a paper conveyer belt. The toner images formed by the printing assemblies of the respective colors are superposed on the paper to form a color image. In order to bring the printing positions into agreement, the printing assemblies print positioning marks on the paper conveyer belt, and an optical sensor reads the marks printed on the paper conveyer belt. Based on the marks thus read out, the printing positions and the printing timings of the plurality of printing assemblies can be adjusted.
The image forming apparatus is further equipped with a top cover which is rotatably mounted on the frame. Upon opening the top cover, the interior of the frame becomes accessible. That is, upon opening the top cover, the constituent members of the print assemblies arranged inside the frame can be repaired or replaced. In particular, the toner must be replenished as it decreases in the developing device. It is desired that the toner can be replenished with ease. Usually, the top cover is locked to the frame by a lock member, and is opened by hand after the locking of the lock member is released.
In the image forming apparatus of the electrostatic recording type, one print assembly includes a photosensitive body, a charger, an optical head, a developing device and a transfer element. The photosensitive body, the charger and the developing device are detachably mounted to the frame as a developing unit. The optical head is mounted to the top cover. When the top cover is opened, therefore, the optical head is lifted together with the top cover. Thus, the user is allowed to access the developing device and so on, and the manufacturer is allowed to maintain the optical heads.
In the image forming apparatus equipped with a plurality of printing assemblies, a plurality of optical heads are mounted to the top cover, and the developing units are detachably mounted to the frame. Moreover, the top cover includes a control board for controlling the optical heads, sheet metal for shielding the control board, and a base frame for mounting the optical heads and the control board. Therefore, the top cover is very heavy. Besides, the image forming apparatus has been designed to be capable of effecting the printing even on large papers and, hence, employs large constituent members, causing the top cover to become even heavier. If the top cover becomes heavier, it is difficult for the operator to lift the top cover. Besides, many constituent members must be efficiently arranged in the limited space in the interior of the apparatus.
A laser beam must not be allowed to leak to the exterior when the top cover is opened. A laser beam which leaks in unexpected directions when the top cover is opened may enter the eyes of the operator. This is not desirable.
SUMMARY OF THE INVENTION
The object of the present invention is to provide an image forming apparatus which enables a top cover to be easily opened and closed, and enables the interior of the frame to be easily accessible upon opening the top cover, facilitating the replacement of expendables and the maintenance and testing of the apparatus.
Another object of the present invention is to provide an image forming apparatus in which the constituent members are efficiently arranged inside the frame.
A further object of the present invention is to provide an image forming apparatus capable of shutting off the optical passage of the optical reading unit when the apparatus is not in use.
The image forming apparatus, according to the present invention comprises a frame, a top cover movably mounted to the frame, a lock member for locking the top cover to the frame, a cover lifting mechanism for lifting the cover by a predetermined amount relative to the frame when the lock member is released, a plurality of print assemblies for forming images of different colors, a fixing device, and a paper conveyer belt for conveying paper through the plurality of printing assemblies and the fixing device. Each of the printing assemblies comprises a photosensitive body, a charger for charging the photosensitive body, an optical head for forming an electrostatic latent image on the photosensitive body, a developing device for developing the electrostatic latent image into a toner image, and a transfer element for transferring the toner image onto a paper, the optical head being mounted to the top cover.
Owing to this constitution, the top cover is lifted up by a predetermined amount relative to the frame by the cover lifting mechanism when the lock member is released. The predetermined amount will be, for example, a distance which permits fingers to be inserted between the frame and the top cover. Therefore, the operator is allowed to easily open the top cover using finger pressure.
The following constitution can be employed together with the above-mentioned constitution.
Provision is made of a switch which is linked to the cover lifting mechanism to detect the opening or closure of the top cover.
The apparatus has a front end and a rear end, the fixing device is disposed near the rear end of the apparatus, and the top cover is mounted to turn about a rotary support point disposed at a position on the rear side of the fixing device.
The cover lifting mechanism is disposed near the front end of the apparatus, and comprises a rod engageable with the top cover, a spring for urging the rod in a direction in which the top cover opens, and a stopper for stopping the rod at a predetermined position.
The photosensitive body, the charger and the developing device in each of the printer assemblies are formed as a developing unit, and the frame has a resin guide for positioning the optical head and the developing unit independently for each of the print assemblies.
The angle of the optical head when the top cover is closed is set to lie over a range of from 91 to 120 degrees with respect to the horizontal from the side of the rotary support point.
The photosensitive body, the charger and the developing device in each of the printing assemblies are formed as a developing unit, and the frame has a guide which permits the developing unit to be attached or detached at an angle over a range of from 1 to 45 degrees with respec
Houki Youji
Nagatomi Tsutomu
Nakayasu Hirofumi
Armstrong Westerman Hattori McLeland & Naughton LLP
Fujitsu Limited
Lee Susan S. Y.
LandOfFree
Image forming apparatus with belt mark sensor does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Image forming apparatus with belt mark sensor, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image forming apparatus with belt mark sensor will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2504893