Dynamic assignment of group addresses for controlling...

Details Dynamic assignment of group addresses for controlling... Dynamic assignment of group addresses for controlling...

1998-08-01

2002-09-10

Mancuso, Joseph (Department: 2724)

Facsimile and static presentation processing

Static presentation processing

Communication

C358S001130, C358S001140

Reexamination Certificate

active

06449054

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Technical Field
This invention relates to document printing and duplication. More particularly, this invention relates to a network for high-speed, parallel document printing and duplication.
2. Description of Related Art
Large offices and fast turn-around copy centers run multiple printers and copy machines in parallel to speed processing of printing and duplication. Conventionally, a digital input document is created on a scanner
103
or other input device. The digitized input document may then be sent through dedicated cables
101
to multiple laser printers
105
or other output devices as shown in FIG.
1
(
a
).
Alternatively, as shown in FIG.
1
(
b
), a network compatible scanner
104
or other input device may send the digitized input document to a local area network (LAN)
102
, such as an Ethernet network, to network compatible laser printers
106
or other output devices. The scanner
104
shown in FIG.
1
(
b
) may be, for example, a GP200 model digital copier available from Canon Inc.
Such networks
102
are conventionally operated by sending packets from the scanner
104
to each individual printer
106
. An individual printer
106
receives from the network
102
those packets which have a destination address identifying the individual printer
106
. Practically speaking, such a system is limited to about six (6) printers
106
when implemented via a 10 megabit per second Ethernet network
102
.
Such a system is shown in FIG.
2
.
FIG. 2
is a schematic diagram showing the data
202
for a document “n” being sent over a conventional network
102
six (6) times by a scanner
104
, in order to be received and printed by six (6) printers
106
. In such a system, the data
202
transmitted over the network
102
must double in order to cause two printers
106
to each produce a copy of the same document. Data
202
transmitted must increase by a factor of N in order to cause N printers
106
to each produce a copy of the same document.
In particular, at a resolution of 600 dots per inch (dpi), an 8.5 inch by 11 inch monochrome scanned image (1 bit per scanned pixel) contains about 4.2 Mbytes of data. Transmitting 4.2 Mbytes of data across a typical 10 BaseT (10 megabits per second) Ethernet network takes approximately 5 seconds. This transmission time is too long and significantly impacts the speed at which multiple copies of the document are printed. The time may be reduced to about 0.5 second by compressing the data (e.g., via JBIG or Group
3
fax compression techniques). Nevertheless, transmitting twenty (20) compressed pages (each 4.2 Mbytes of data before compression) still requires about ten (10) seconds of network transfer time. This is still a substantially long time, which adversely affects system performance.
From the above discussion, it is apparent that what is needed is a system in which the network transfer time of a document to multiple printers is decreased in order to enhance the speed at which multiple copies may be printed.
SUMMARY OF THE INVENTION
In order to avoid the above discussed drawbacks, a high-speed, parallel document printing and duplication system sets up each of the multiple laser printers (
106
) with each a conventional individual network address and a new shared group network address. Each printer (
106
) “listens” to the network (
102
) for document data (
402
) sent to its group address. The assignment of printers (
106
) to sending devices (
104
) is controlled by a dynamic group addressing computer (
302
). Each printer (
106
) also may confirm receipt of document data (
402
) by sending a confirmation packet to the sending device (
104
). Such a system permits large numbers of printers (
106
) to receive each document without crowding the network (
102
) bandwidth and slowing system performance. Moreover, such a system enables dynamic reconfiguration of group assignments, which results in flexibility in the use of the multiple printers (
106
) to simultaneously print a number of jobs at various speeds.


REFERENCES:
patent: 5528605 (1996-06-01), Ywoskus et al.
patent: 5548578 (1996-08-01), Matsune et al.
patent: 6049528 (2000-04-01), Hendel et al.

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