Electrophotography – Machine operation
Reexamination Certificate
2002-11-22
2004-06-22
Chen, Sophia S. (Department: 2852)
Electrophotography
Machine operation
C399S401000
Reexamination Certificate
active
06754456
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 2002-12988, filed Mar. 11, 2002, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electrophotographic image forming apparatus having a duplex function, and more particularly, to a drive mechanism for an electrophotographic printer capable of operating an image forming apparatus using a low capacity motor and efficiently having a duplex function.
2. Description of the Related Art
An electrophotographic image forming apparatus is an apparatus, such as a printer or copier, that prints by forming an electrostatic latent image on a photosensitive body using a laser, developing this image using a developing agent, and transferring the image to an image transfer body. The present invention will be explained by referring to a laser printer, however, the present invention may be applied to any electrophotographic image forming apparatus.
Referring to
FIG. 1
, an electrophotographic image forming apparatus having a duplex printing function has a paper feeding unit, a developing unit, a fixing unit, a delivery unit and a duplex printing unit. This apparatus also includes a drive mechanism, which may be the known drive mechanism of
FIG. 2
, or the drive mechanism according to an embodiment of the present invention, as shown in
FIGS. 3 and 4
.
The paper feeding unit supplies an image transfer body (such as a sheet of paper) and includes a paper feeding cassette
1
, a feeding unit transfer roller
5
, and a registration roller
7
. Also, the paper-feeding unit can include a manual paper feeding tray
13
that can supply various types of image transfer bodies.
The paper feeding cassette
1
stacks a large number of the image transfer bodies and has a pickup roller
3
at the front end thereof to supply the stacked image transfer bodies one by one. The feeding unit transfer roller
5
conveys the image transfer body supplied by the pickup roller
3
to the registration roller
7
. The registration roller
7
aligns the front end of the image transfer body conveyed from the feeding unit transfer roller
5
and supplies the image transfer body to the developing unit. The manual paper feeding tray
13
supplies various types of image transfer bodies such as OHP film, an envelope or a labeling sheet, and conveys the image transfer body stacked on the manual paper feeding tray
13
to the registration roller
7
, using a multipurpose pickup roller
11
installed at the front end thereof.
The developing unit forms an image on the image transfer body according to the printing content transferred from a computer, and includes a laser scan unit
20
, a developing device
19
, an OPC drum
15
, and a developing unit transfer roller
17
.
The laser scan unit
20
is installed above the OPC drum
15
and scans a laser beam corresponding to the printing content according to a command from an image forming apparatus controller (not shown) on the OPC drum
15
.
The OPC drum
15
has a surface on which an electrostatic latent image is formed according to the laser beam and is installed above the developing unit transfer roller
17
. The electrostatic latent image is developed as a visible image by the developing agent supplied by the developing device
19
as the OPC drum
15
rotates, and the developed visible image is transferred to the image transfer body by the developing unit transfer roller
17
. The developing device
19
has the developing agent and develops an electrostatic latent image to a visible image by supplying the developing agent to the OPC drum
15
.
The fixing unit fixes an image, transferred by the developing unit to the image transfer body, on the image transfer body using heat and pressure, and has a fixing roller
21
and a pressure roller
23
.
A delivery unit discharges the image transfer body from the fixing unit when printing is completed and has a first delivery roller
25
, a second delivery roller
27
, a third delivery roller
31
and a delivery convey guide
33
.
In the case of duplex printing, a duplex printing unit returns a one-side printed image transfer body to the transfer roller
5
. Then the image transfer body returned to the transfer roller
5
passes the developing unit and the fixing unit to print on the other side. The duplex printing unit has a first duplex roller
35
, a first duplex convey guide
37
, a second duplex convey guide
39
, and a second duplex roller
41
to return the image transfer body. The first duplex roller
35
is installed in contact with the second delivery roller
27
, with an idle roller
29
therebetween.
A drive mechanism driving each structural unit of the electrophotographic image forming apparatus as described above will now be explained. The drive mechanism is installed at one side of each structural unit.
Referring to
FIG. 2
, a conventional drive mechanism of the electrophotographic image forming apparatus capable of duplex printing of
FIG. 1
has a first driving part and a second driving part.
The first driving part drives all described structural units except the third delivery roller
31
and has a first driving motor
50
, a first gear train
51
, and a second gear train
71
.
The first gear train
51
transmits the power of the first driving motor
50
to the pickup roller
3
, the transfer roller
5
, and the registration roller
7
and has an intermediate gear train
55
and a pickup roller gear train
59
. If the manual paper feeding tray
13
is attached, the first gear train
51
additionally has a multipurpose pickup roller gear train
69
for driving the manual paper feeding tray
13
.
A gear
52
at one end of the intermediate gear train
55
is engaged with a pinion
50
′ of the first driving motor
50
. An intervening gear
54
at the other end of the intermediate gear train
55
is engaged with a registration gear
63
coaxially connected with the registration roller
7
and a transfer roller gear train
61
coaxially connected with the transfer roller
5
. A gear
56
at one end of the pickup roller gear train
59
is engaged with the intermediate gear train
55
and the other end includes a pickup roller gear
58
coaxially connected with the pickup roller
3
. One end of the multipurpose pickup roller gear train
69
is a reverse roller gear
65
engaged with the transfer roller gear train
61
and the other end includes a multipurpose pickup roller gear
67
coaxially connected with the multipurpose pickup roller
11
. The reverse roller gear
65
is coaxially connected with a reverse roller
9
conveying the image transfer body together with the feeding unit transfer roller
5
.
The second gear train
71
transmits the power of the first driving motor
50
to the OPC drum
15
, the fixing roller
21
, the first delivery roller
25
, the first duplex roller gear
35
, and the second duplex roller
41
, and has an OPC drum gear train
75
, a fixing roller gear train and a second duplex roller gear train
93
having gears
91
and
92
.
The OPC drum gear train
75
has a transmission gear
72
at one end, which is engaged with the pinion
50
′ of the first driving motor
50
, and an OPC drum gear
74
at the other end, which is coaxially connected with the OPC drum
15
. The fixing roller gear train includes sub-fixing roller gear train
80
, a first delivery roller gear train
85
and a first duplex roller gear train
89
. The sub-fixing roller gear train
80
has a gear
77
at one end, which is engaged with the transmission gear
72
of the OPC drum gear train
75
, and a gear at the other end, which includes a fixing roller gear
79
coaxially connected with the fixing roller
21
. A gear
82
at one end of the first fixing roller gear train
85
is engaged with the fixing roller gear
79
, and the other end includes a first delivery roller gear
84
, coaxially connected with the first delivery roller
25
. A gear
86
at one end of the first dup
Chen Sophia S.
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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