Incremental printing of symbolic information – Electric marking apparatus or processes – Electrostatic
Reexamination Certificate
1999-12-13
2001-06-26
Brase, Sandra (Department: 2852)
Incremental printing of symbolic information
Electric marking apparatus or processes
Electrostatic
C347S152000, C399S125000
Reexamination Certificate
active
06252619
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image-forming apparatus, and more particularly to the construction in an image-forming apparatus of a guide mechanism for guiding a printhead with respect to a print process cartridge.
2. Description of the Related Art
FIG. 21
is a perspective view of a conventional electrophotographic image-forming apparatus.
The conventional apparatus includes a rotatable lid
1
and a stationary main body
3
. The lid
1
is pivotally mounted to the main body
3
so that the lid
1
can be opened and closed relative to the main body
3
. The main body
3
incorporates a print process cartridge
7
having a photoconductive drum, not shown. There is provided an operating panel
3
a
at the front end of the main body
3
. Operating buttons and other controls, not shown, are provided on the operating panel
3
a.
Shafts
4
are provided at the rear end portions of opposed side walls of the main body
3
and extend toward each other into bearing holes
2
formed in the end portion of the lid
1
. Thus, when the lid
1
is rotated in a direction shown by arrow A, the lid
1
closes the opening of the main body
3
. A printhead assembly
6
having a printhead
5
therein is attached to the forward underside of the lid
1
. The printhead
5
is loosely held in the printhead assembly
6
so that the printhead
5
is movable to some extent within the printhead assembly
6
.
When the lid
1
is rotated in the direction shown by arrow A, the printhead
5
moves along an arcuate path into mating engagement with the print process cartridge
7
. The printhead
5
is formed with projections
5
a
at longitudinal end portions thereof. The print process cartridge
7
is formed with recesses, not shown, which receive the projections
5
a.
When the lid
1
closes the main body
3
, the projections
5
a
completely fit into the recesses in the print process cartridge
7
, so that the printhead
5
is accurately positioned with respect to the photoconductive drum in the print process cartridge
7
.
The printhead assembly
6
incorporates a compression spring, not shown. When the printhead
5
is fitted into the print process cartridge
7
, the compression spring urges the printhead
5
against the print process cartridge
7
, thereby preventing the printhead
5
from rattling. Pressing the printhead
5
against the print process cartridge
7
holds the printhead
5
at an accurate position relative to the photoconductive drum, thereby ensuring good print quality.
The operation of the aforementioned conventional image-forming apparatus will be described.
The compression spring urges printhead
5
outwardly from the printhead assembly
6
such that the printhead
5
is resiliently movable in the printhead assembly
6
. When the lid
1
is opened, the printhead
5
abuts part of the printhead assembly
6
. When the lid
1
is closed, the printhead
5
first engages the print process cartridge
7
and is pushed back by the print process cartridge into the housing of the printhead assembly
6
against the urging force of the compressed spring, so that the spring is further compressed.
The compression spring is compressed more when the lid
1
is closed than when the lid
1
is opened. Thus, the position of the printhead
5
when the lid
1
is opened differs from that when the lid
1
is completely closed.
Therefore, it is necessary to precisely adjust the position of printhead
5
with respect to the printhead assembly
6
after the projections
5
a
of the printhead
5
are fitted into the recesses formed in the print process cartridge
7
.
Thus, the orientation of the printhead
5
must be gradually changed in accordance with the rotation of the lid
1
so that while the lid
1
rotates in the arcuate path, the projections
5
a
are properly received into the recesses in the print process cartridge
7
. The housing of the printhead assembly
6
must be shaped, taking into consideration where in the arcuate path of the printhead
5
the print process cartridge
7
receives the printhead
5
. Thus, the housing has a complicated shape and must be manufactured with a high level of dimensional accuracy.
If the housing of the printhead assembly
6
is shaped such that the orientation of the printhead
5
gradually changes as the lid
1
rotates, the compression spring may urge the printhead
5
in directions that are different from the orientation of the printhead
5
depending on the rotational position of the lid
1
. The printhead
5
may not be smoothly oriented according to the shape of the housing. A similar problem occurs when the compression spring has not enough biasing force.
In an attempt to solve the aforementioned problems, the compression spring maybe other shapes, e.g., a cone-shaped spring, than an ordinary cylindrical coil spring. Further, springs having low spring constants or long springs may be used. However, springs of complicated shapes will be expensive.
SUMMARY OF THE INVENTION
The present invention is made in view of the aforementioned problems of the conventional apparatus.
An object of the invention is to provide an image-forming apparatus capable of printing with stable, reliable print quality.
Another object of the invention is to provide an image-forming apparatus where the housing of the printhead assembly that holds the printhead therein can be of a simple shape and therefore can be manufactured at low cost.
An image-forming apparatus according to the present invention comprises first, second, and third assemblies and a guide mechanism. The first assembly is a stationary main body that accommodates a print process cartridge therein. The main body has an opening that opens upward of the image-forming apparatus. The second assembly is a lid assembly that is rotatably, or pivotally, supported on the first assembly so that the second assembly is rotatable about an axis to open and close the opening. The third assembly is an exposing unit mounted to an inner side of the second assembly and extending parallel to the axis. The third assembly moves into mating engagement with the print process cartridge when the second assembly has completely closed the opening. The guide mechanism guides the third assembly into mating engagement with the print process cartridge when the second assembly is rotated. The guide mechanism may include the member of the holder that define a hole therein, a projection that projects from the third assembly and extends through the hole, and a guide groove into which the projection enters to be guided to the print process cartridge.
The second assembly includes a holder and an urging member. The holder loosely holds the third assembly. The urging member urges the exposing assembly in a direction in which the guide groove extends, against the print process cartridge when the third assembly has moved into mating engagement with the print process cartridge. The holder has a member that defines a hole therein. The guide mechanism includes the member that defines the hole in the holder, a projection that projects from said third assembly parallel to the axis and extends through the hole, and a guide groove formed in said first assembly. The guide groove receives the projection therein such that the projection is slidable in the guide groove.
The print process cartridge has a surface that extends parallel to the groove. The third assembly includes a support attached to an end of the third assembly. The support has a first projection that loosely projects parallel to the axis into the hole and a second projection that projects in a direction perpendicular axis. When the second assembly is rotated about the axis to close the opening, the second projection moves into contact engagement with the surface and then slides on the surface until the third assembly moves into mating engagement with the print process cartridge. The axis is substantially at a midway point of a distance over which the second projection slides on the surface until the third assembly has moved into m
Ueda Hidenori
Wakana Takashi
Brase Sandra
Oki Data Corporation
Rabin & Champagne, P.C.
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