Dual aldc decompressors inside printer asic

Details Dual aldc decompressors inside printer asic Dual aldc decompressors inside printer asic

2000-04-14

2001-10-09

Jeanpierre, Peguy (Department: 2819)

Coded data generation or conversion

Digital code to digital code converters

C358S001200, C714S819000

Reexamination Certificate

active

06300885

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to data buffering/transformation systems, in particular to data buffering/transformation systems that utilize lossless compression and decompression algorithms or hardware to maximize limited memory resources.
2. Description of Related Art
In prior art buffering/transformation systems such as system
10
shown in
FIG. 1
, data is received and then buffered or stored in a data storage unit
12
prior to transmission. The received data may be buffered because it is received at a data rate greater than the data rate of the transmitted data. In addition, the received data may be data that needs to be transformed to a different format before it can be transmitted. In such embodiments, the received data may be buffered or stored in the data storage unit
12
prior to its transformation and transmission.
In either case, the data is stored or buffered temporarily in the data storage unit
12
. The data storage unit
12
capacity may be determined as a function of the differential data rates (input/output rate), burst rates, and the time required to transform the received data. Due to high storage prices, the storage cost that the buffering/transformation system
10
requires can be prohibitive. In order to reduce the storage size (total effective storage capacity) and, thus the system cost, some prior art systems have added a combination compressor/decompressor (“C/D”)
14
.
The C/D
14
compresses received data prior to storage in the data storage unit
12
. Consequently, the storage requirements for the system
10
may be reduced. The C/D
14
also decompresses data stored in the data storage unit
12
prior to transmission. Preferably, the received data is compressed using a lossless compression algorithm such as Adaptive Lossless Data Compression (“ALDC”), which is well known by those of ordinary skill in the art. See, for example, commonly assigned U.S. Pat. No. 5,572,209 “Method and apparatus for compressing and decompressing data,” Farmer et al. issued Nov. 5, 1996.
In conventional systems that transform or manipulate data prior to transmitting the data, data is received, compressed, and then stored in its received or raw format in the data storage unit
12
. Data in the data storage unit
12
may then be retrieved, decompressed by C/D
14
, and transformed for transmission. A transmission system may be coupled to the system
10
to receive the transmitted data. Depending on the transmission system's rate or status, the transformed data may also need to be buffered prior to transmission. C/D
14
compresses the transformed data and stores the compressed transformed data in data storage unit
12
. Next, C/D
14
retrieves the transformed data in data storage unit
12
, decompresses the data, and transmits the decompressed data. Thus, C/D
14
is required to decompress stored, compressed, received or raw data so that the data can be transformed, compressed, and returned to memory. C/D
14
is further required to decompress stored, compressed, transformed data to be transmitted. C/D
14
may limit system
10
throughput due to the simultaneous decompression demands.
A data buffering/transformation system is needed to overcome these and other problems of the prior art.
SUMMARY OF THE INVENTION
The present invention provides a data buffering system that can decompress raw or received data while decompressing transformed data. The data buffering system includes a combination compressor and first decompressor which is coupled to a data storage unit. The system also includes a second decompressor coupled to the data storage unit. In this system, the combination compressor and first decompressor compress a received data signal for storage in the data storage unit. The second decompressor decompresses the compressed received data signal.
In one embodiment of the data buffering system, the combination compressor and first decompressor as well as the second decompressor are all lossless. Further, the received data signal may be an encoded data signal. The data buffering system is coupled to a data processing unit. The combination compressor and first decompressor decompresses the compressed received data signal stored in the data storage unit and passes the decompressed data signal to the data processing unit. The data processing unit converts the encoded data signal into a decoded received data signal. Further, the combination compressor and first decompressor compresses the decoded received data signal for storage in the data storage unit. The second decompressor then decompresses the compressed decoded received data signal stored in the data storage unit.
In a further embodiment the received data signal is an encoded print signal and the decompressed decoded data signal is a decoded print signal. The data buffering system is a data buffering/transformation system that transforms an encoded data signal into a decoded data signal.


REFERENCES:
patent: 3980809 (1976-09-01), Cook
patent: 5050006 (1991-09-01), Ogawa
patent: 5247638 (1993-09-01), O'Brien et al.
patent: 5572209 (1996-11-01), Farmer et al.
patent: 5704020 (1997-12-01), Hanyu et al.
patent: 5740282 (1998-04-01), Hurd
patent: 6002814 (1999-12-01), Chadez
patent: 6026508 (2000-02-01), Craft
patent: 6121903 (2000-09-01), Kalkstein
patent: 6130630 (2000-10-01), Grohs et al.

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