Electrophotography – Machine operation
Reexamination Certificate
2003-07-22
2004-11-30
Ngo, Hoang (Department: 2852)
Electrophotography
Machine operation
C399S090000
Reexamination Certificate
active
06826376
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
This application claims the benefit of Korean Application No. 2002-43017, filed Jul. 22, 2002, Korean Application No. 2003-10809, filed Feb. 20, 2003, and Korean Application No. 2003-40666, filed Jul. 21, 2003, all filed in the Korean Intellectual Property Office, the disclosures of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an image forming apparatus, and more particularly to an image forming apparatus that is readily redesignable for purposes such as an addition of an improvement or a new function, and a component arrangement method of the same.
2. Description of the Related Art
Image forming apparatuses such as laser printers receive print data from an image processing apparatus such as a personal computer and reproduce the received print data on a printing medium such as a paper sheet. Recently, such image forming apparatuses have been incorporated into a multi-functioned machine such as a fax-copier image forming apparatus.
As the image forming apparatus technology rapidly advances, the molding and the printed circuit board (PCB) are requiring more frequent updating. However, the metal molding by nature requires a longer time than the PCB for a design process, and also requires a reliability test after the design is completed. Accordingly, there is usually a three to five year interval until the image forming apparatus is redesigned, and usually, it is the PCB which is the subject of the redesign.
Meanwhile, due to individual characteristics, the design for the metal mold and the PCB are usually planned by separate companies. Thus, the metal mold generally needs to be equipped with various motors to drive the image forming apparatus and a PCB to control the motors. Usually, the motor and the PCB for motor control are available as a set, and when used to design the image forming apparatus, because the PCB has a verified quality, a reliability test time may be reduced. In contrast, if one buys the metal mold and PCB separately and attempts to design an image forming apparatus using them, since the user is also required to prepare and install components such as a random access memory and Flash ROM (or mask ROM, or EPROM) to store programs to drive the processor, the user would require a significant amount of time to complete the design.
FIG. 1
is a block diagram of an example of a conventional laser printer. The laser printer includes an image processing unit
20
, a switching mode power supply (SMPS)
30
, an engine controlling unit
40
, a high voltage power supply (HVPS)
50
and an engine mechanism
60
.
The image processing unit
20
converts the print data received from a host computer
10
into image data such as bit map data which are processible at the engine controlling unit
40
. The SMPS
30
generates power for driving the image processing unit
20
, the engine controlling unit
40
, the HVPS
50
and the engine mechanism
60
. The engine controlling unit
40
controls the driving of the engine mechanism
60
in accordance with the image data applied from the image processing unit
20
. The engine mechanism
60
is driven by the engine controlling unit
40
to reproduce an image on the printing medium such as a paper, and includes necessary mechanical devices such as a motor, a roller and an organic photoconductor (OPC). The engine controlling unit
40
includes a processor (not shown), a random access memory (not shown) and a Flash ROM (or mask ROM, or EEPROM; not shown) to drive the processor. The engine controlling unit
40
controls the operation of the mechanical devices such as a motor, a roller and an OPC in response to the image data.
FIGS. 2A and 2B
are block diagrams of the image processing unit
20
and the engine controlling unit
40
of FIG.
1
. First, the image processing unit
20
of
FIG. 2A
includes an interface unit
21
which receives the print data from the host computer
10
, a central processing unit (CPU)
23
to control the overall operation of the image processing unit
20
, a ROM
22
to store various control programs and application programs for driving the CPU
22
, a random access memory (RAM)
24
to temporarily store data generated during the print data processing, and an EEPROM
25
for storing initial conditions or control set values of the image processing unit
20
.
The engine controlling unit
40
shown in
FIG. 2B
includes a ROM
41
to load control programs for the turn-on or resetting of the engine controlling unit
20
on the CPU
42
, a CPU
42
to control the overall operation of the engine controlling unit
40
according to the programs stored in the ROM
41
, a random access memory (RAM)
43
to temporarily store the data generated by the program execution of the CPU
42
, an EEPROM
44
to store set values for setting control data or the operational states of the engine mechanism
60
, and an engine interface unit
45
to provide interface between the engine mechanism
60
and the CPU
42
.
As described above, conventionally, the engine controlling unit
40
and the image processing unit
20
were formed on separate PCBs, each of which being equipped with the processor
23
,
42
, the ROM
22
,
41
, the random access memory
24
,
43
and the EEPROM
25
,
44
. Accordingly, a separate interface (not shown) was required for the data transmission between the processors
23
,
42
of the two separate PCBs. For example, for the processors
23
,
42
to support different input/output interfaces, an interface circuit is inevitably required to convert two different data formats of the processors
23
,
42
. The requirement for the extra parts such as an interface circuit increases the unit price of the image forming apparatus, while degrading the data transmission speed between the processors
23
,
43
.
FIG. 3
is a schematic sectional view illustrating the engine mechanism
60
of FIG.
1
. The engine mechanism
60
includes a photosensitive drum
61
having an electrically-chargeable layer to facilitate formation of an electric potential difference at the area charged by the exposure to the light of the light source, a laser scanning unit (LSU)
63
which converts the image data into optical signals, irradiates the optical signals onto the photosensitive drum
61
to form an electrostatic latent image by the electric potential difference, a developing unit
64
which sequentially supplies toners of respective colors onto the photosensitive drum
61
, a transfer unit
65
which transfers the toner image from the photosensitive drum
61
onto a printing paper P, and a fusing unit
66
which fixes the transferred toner image on the printing paper P.
The developing unit
64
includes four toner reservoirs
64
a
~
64
d
that sequentially feed toners of respective colors such as yellow Y, magenta M, cyan C and black B to develop the image on the photosensitive drum
61
. The reference numeral
64
e
denotes a developing roller which applies yellow color toner onto the photosensitive drum
61
. Although not shown, the developing roller is also provided to the other toner reservoirs
64
b
~
64
d.
The transfer unit
65
includes a transfer belt
65
a
that serves as a transfer medium for the toner image of the photosensitive drum
61
, a first transfer roller
65
b
which transfers the toner image of the photosensitive drum
61
onto the transfer belt
65
a
, and a second transfer roller
65
c
which transfers the toner image of the transfer belt
65
a
onto the printing paper P.
The image forming apparatus, constructed as above, forms a desired electrostatic latent image on the photosensitive drum
61
as the laser beam is irradiated from the LSU
63
onto certain areas of the photosensitive drum
61
that is charged to a predetermined potential by the charging unit
62
.
Next, the electrostatic latent image is developed by the developing unit
64
, in which usually the yellow Y, magenta M, cyan C and black B toners of the toner reservoirs
64
a
~
64
d
are sequentially fed onto the photosensitiv
An Seung-deog
Eom Yoon-seop
Kim Yong-geun
Park Sang-sin
Yang Cheol-ju
Ngo Hoang
Samsung Electronics Co,. Ltd.
Staas & Halsey , LLP
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