Facsimile and static presentation processing – Static presentation processing – Communication
Reexamination Certificate
1998-08-13
2001-04-24
Popovici, Dov (Department: 2622)
Facsimile and static presentation processing
Static presentation processing
Communication
C358S001160
Reexamination Certificate
active
06222636
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed to a method and apparatus for storing images (rasters) on one or more disk drives for subsequent printing on a high-speed copier or printer. Compressed images are stored in a disk storage module that minimizes the disk transfer bandwidth required while optimizing overall system throughput.
BACKGROUND OF THE INVENTION
High-speed digital copiers and printers require temporary storage for images prior to printing them. This image storage subsystem serves two important purposes. First, it decouples the speed at which input images are acquired (scanned or rasterized) from the speed at which they are printed. Second, the temporary storage allows multiple copies of a document to be produced without having to re-acquire the input images; i.e., rescan the document or in the case of an input from a computer rerasterize the data from a coded form or object form used in a page description language. For high-volume printing, where multiple sets of large documents need to be produced, the temporary storage is most economically implemented using disk drives. Compressing the images before they are stored on the disks can further increase the capacity of the temporary storage.
A system using disk drives to store images prior to printing them is disclosed in U.S. Pat. No. 5,142,667 to Dimperio et al. The patent describes a system which uses several disk drives to implement a disk memory which is used to store images prior to subsequent processing or printing. Dimperio et al. describe various experiments and algorithms for determining the throughput of the system based on the disk bandwidth, but do not determine the minimum disk bandwidth required for full output productivity.
U.S. Pat. No. 5,495,339 to Stegbauer et al. similarly discloses a disk memory for image storage. This patent also discloses the use of a resource manager to schedule the use of the disk drives. Since the disclosed system may not have sufficient disk bandwidth to read images in time to optimally print them, the resource manager determines when it is necessary to reduce output productivity by inserting a print pitch skip. A similar resource management approach is disclosed by May et al. in U.S. Pat. No. 5,375,202. Both of these resource managers require predicting when a series of disk access operations will be completed in the future. Such predictions are difficult to make given the variability of disk access times and the inability to predict when disk soft errors will occur.
A system that uses image compression in conjunction with a disk memory is disclosed in U.S. Pat. No. 5,130,809 to Takayanagi. By using a compression algorithm that operates at a constant compression rate, the size of the image is reduced and the disk bandwidth required to store the image is similarly reduced. However, to achieve the constant compression rate disclosed by Takayanagi, a non-lossless compression algorithm, such as block approximation or adaptive prediction coding, must be used. This results in reduced image quality when the image is subsequently printed, since the decompressed image is not identical to the original input image.
U.S. Pat. No. 5,611,024 to Campbell et al. discloses the use of a lossless image compression algorithm to reduce the amount of memory required to store an image. The compressed images are stored in solid-state memory that is intended to store only a small number of pages. The system disclosed by Campbell et al. does not use disk drives to achieve the capacity required for high-volume printing in which large numbers of images must be stored to maximize output productivity. Without using disk drives, the images would have to be stored in solid-state memory, which is considerably more expensive.
SUMMARY OF THE INVENTION
It is an object of the invention to optimize overall printing system performance by maximizing the output productivity of the marking engine. Therefore, the disk storage module is able to provide data at the rate required to keep the marking engine running at full capacity for any sequence of images printed on the printing system.
Another object of the invention is to efficiently maximize the number of images that can be stored in the image storage subsystem. Therefore, the images are compressed before they are placed in the disk storage module, and decompressed before they are needed for further image processing or printing.
Yet another object of the invention is to provide a means to load images into the image storage subsystem at substantially the same time images are being retrieved for processing or printing. Operation in this manner prevents the image storage subsystem from restricting the flow of images through the printing system and enables the overall performance of the printing system to be maximized.
Briefly, the invention is directed to an electronic image storage subsystem that is part of a larger printing system. The image storage subsystem provides temporary storage for images prior to subsequent processing or printing. The subsystem is based on a disk storage module which stores compressed images until they are needed. The disk storage module has an aggregate bandwidth sufficient for printing worst-case compressed images at the full rated speed of the marking engine.
In accordance with a first aspect of the invention there is provided a printer apparatus comprising a marking engine subsystem for recording information on an image recording member at a maximum sustainable data recording rate; and an image storage subsystem for buffering image data for output to the marking engine subsystem, the image storage subsystem including an input for receiving rasterized image data a data compressor that operates on the rasterized image data to compress the rasterized image data to form compressed image data a disk storage module that receives, stores and outputs the compressed image data a semiconductor RAM memory device that stores at least one page of the compressed data a data decompressor that operates on the compressed data output by the RAM memory device and decompresses the compressed data to decompressed rasterized image data for output to the marking engine subsystem; and a RAM controller that controls the RAM memory device for outputting the compressed data from the RAM memory device to the decompressor, the disk storage module outputting compressed data to the RAM memory device at a data rate fast enough so that when the data is decompressed the decompressed rasterized image data is available to the marking engine to operate at the maximum sustainable recording rate of the marking engine subsystem.
In accordance with a second aspect of the invention there is provided a method of operating an image storage subsystem for output of image data to a marking engine subsystem for recording information on an image recording member at a maximum sustainable data recording rate, the method comprising inputting rasterized image data to a data compressor device, a compressing the rasterized image data to form compressed image data, a storing the compressed image data in a disk storage module, outputting the compressed image data from the disk storage module to a semiconductor RAM memory device that stores at least one page of the compressed image data and decompressing the compressed data to decompressed rasterized data for output to the marking engine subsystem. The disk storage module outputs compressed image data to the RAM memory device at a data rate fast enough so that when the data is decompressed the decompressed rasterized image data is available to the marking engine so as to allow the marking engine to operate at the maximum sustainable data recording rate of the marking engine subsystem.
REFERENCES:
patent: 4949190 (1990-08-01), Thompson
patent: 5047955 (1991-09-01), Shope et al.
patent: 5130809 (1992-07-01), Takayanagi
patent: 5142667 (1992-08-01), Dimperio et al.
patent: 5170263 (1992-12-01), Hisatake et al.
patent: 5367383 (1994-11-01), Godshalk et al.
patent: 5375202 (1994-12-01), May et al.
patent: 5384646 (1995-01-01), Godshalk
Leimbach James D.
Nek Press Solutions LLC
Popovici Dov
LandOfFree
Disk-based image storage system invention disclosure does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Disk-based image storage system invention disclosure, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Disk-based image storage system invention disclosure will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2459179