Typewriting machines – Sheet or web – Including programmed-control-system for record-medium feed
Reexamination Certificate
2000-12-20
2003-10-21
Nolan, Jr., Charles H. (Department: 2854)
Typewriting machines
Sheet or web
Including programmed-control-system for record-medium feed
C400S061000, C400S070000, C400S076000, C400S613000
Reexamination Certificate
active
06634817
ABSTRACT:
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 which can use a functional unit that can be detachably mounted in a main body of the image forming apparatus and that includes a nonvolatile memory capable of communicating with the main body of the image forming apparatus.
2. Description of the Related Art
FIG. 9
is a cross-sectional view illustrating the configuration of an electrophotographic printer, serving as an image forming apparatus.
In
FIG. 9
, an electrostatic latent image is formed on a photosensitive drum
1
. A charging roller
2
uniformly charges the photosensitive drum
1
. An optical unit
6
scans the photosensitive drum
1
with a laser beam
6
. The laser beam
6
is emitted from the optical unit
5
. A developing unit
3
develops the electrostatic latent image formed on the photosensitive drum
1
by the laser beam
6
, using a toner.
A transfer roller
4
transfers the toner image formed on the photosensitive drum
1
onto a predetermined sheet. A fixing unit
7
fuses and fixes the toner on the sheet. Printing sheets are mounted in a standard cassette
8
. A standard-cassette sheet feeding roller
9
picks up a sheet from the standard cassette
8
.
There are also shown a manual sheet insertion tray
10
, and a manually-inserted-sheet feeding roller
11
. Discharging rollers
12
discharge the sheet to the outside of the printer. A registration sensor
13
performs registration of the leading edge of the sheet for printing by detecting the leading edge of the conveyed sheet. A discharged-sheet sensor
14
confirms that the sheet has normally been discharged through the fixing unit
7
. A sensor
15
detects the presence/absence of sheets in the standard cassette
8
. A sensor
16
detects the presence/absence of sheets for manual insertion. A process cartridge
17
includes the photosensitive drum
1
, the charging roller
2
and the developing unit
3
, and is detachable relative to the main body of the printer. The sheet after printing is discharged onto a discharged-sheet tray
18
.
Each of these units operates according to an instruction from an engine control unit (to be described later). The engine control unit also performs printing processing by controlling the units based on instructions from a printer controller (to be described later).
The process cartridge
17
is usually used in order to facilitate maintenance of the printer. It has been proposed to provide a nonvolatile memory within the process cartridge
17
, and write data relating to the state of use of the process cartridge
17
and other data in the nonvolatile memory, for example, in order to control the life of the photosensitive drum
1
included in the process cartridge
17
.
FIG. 10
is a block diagram illustrating an example of control units of the printer.
In
FIG. 10
, a printer controller
101
performs communication with a host computer, develops received image data into information that can be printed by the printer, and exchanges signals with an engine control unit
102
. The engine control unit
102
controls the respective units within the printer by means of serial communication.
A sheet-conveyance control unit
103
executes feeding and conveyance of the printing sheet from each sheet feeding unit (or sheet feeding tray) to the discharged-sheet tray
18
, based on instructions from the engine control unit
102
. An optical-system control unit
104
executes driving of a scanner motor for scanning the photosensitive drum
1
by the laser beam
6
, and on/off control of the laser beam
6
, based on instructions from the engine control unit
102
. A high-voltage-system control unit
105
provides high-voltage outputs necessary for an electrophotographic process, such as charging, development, transfer and the like, based on instructions from the engine control unit
102
.
A fixing-temperature control unit
106
performs temperature control of the fixing unit
7
based on an instruction from the engine control unit
102
, detection of abnormality in the fixing unit
7
, and the like, based on instructions from the engine control unit
102
. A sheet-sensor input unit
107
transmits information from sheet sensors within the sheet feeding units (the cassette and the tray) and a sheet conveying path to the engine control unit
102
. A jam detection unit
108
detects a failure during sheet conveyance. A failure detection unit
109
detects a failure within the printer. A process cartridge in which, as shown in
FIG. 10
, a nonvolatile memory
111
capable of exchanging data with the engine control unit
102
is mounted, and data can be read from and written into the engine control unit
102
has also been proposed as the process cartridge
17
.
In the above-described configuration, the following approach may be considered as an approach for accessing the nonvolatile memory
111
from the printer controller
101
.
The engine control unit
102
performs the processing of reading the entire contents of the nonvolatile memory
111
with a predetermined timing, and storing the read contents into a memory (not shown) within the engine control unit
102
. When the engine control unit
102
is requested the contents of the nonvolatile memory
111
from the printer controller
101
, the contents which have been read from the nonvolatile memory
111
and stored in the memory within the engine control unit
102
are transmitted to the printer controller
101
.
FIG. 11
illustrates a protocol for such processing in the form of a timing chart.
A /SCLK signal is a clock signal for synchronism of serial communication output from the printer controller
101
to the engine control unit
102
. A /SC signal is a command/status signal output/responded in synchronization with the clock signal for synchronism. A command is instruction information output from the printer controller
101
to the engine controller
102
. A status is status information relating to the engine control unit
102
transmitted from the engine control unit
102
in response to the command from the printer controller
101
.
Upon reception of a command
120
to request reading of memory contents A from the printer controller
101
, the engine control unit
102
instantaneously transmits information relating to the memory contents A read in advance from the nonvolatile memory
111
and stored in the memory of the engine control unit
102
, as status data
121
.
However, since the above-described approach is specified such that the engine control unit
102
instantaneously responds to a request of reading/writing of the contents of the memory
111
from the printer controller
101
, the engine control unit
102
must acquire in advance the entire contents of the nonvolatile memory
111
and store the acquired contents in the memory provided in the engine control unit
102
.
Accordingly, the engine control unit
102
must have a surplus memory capacity covering the capacity of the nonvolatile memory
111
. If information to be stored in the nonvolatile memory
111
increases, not only the memory capacity of the nonvolatile memory
111
but also the memory capacity of the engine control unit
102
must be increased, resulting in an increase in the cost of the apparatus.
Particularly if a cartridge mounting a nonvolatile memory whose capacity is larger than the capacity of the memory incorporated in the engine control unit
102
appears in the future, there is the possibility that the cartridge
17
cannot be normally utilized if the capacity of the memory of the engine control unit
102
cannot be increased.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an image forming apparatus in which a detachable unit mounting a memory is mountable in a main body of the apparatus, and in which the capacity of a memory mounted in the main body of the apparatus can be smaller than the capacity of the memory mounted in the detachable unit.
It is another object of the present invention to provide
Canon Kabushiki Kaisha
Fitzpatrick ,Cella, Harper & Scinto
Nolan, Jr. Charles H.
LandOfFree
Image forming apparatus 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, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Image forming apparatus will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3126569