Typewriting machines – Including control of format and selection of type-face by...
Reexamination Certificate
2001-01-23
2004-10-19
Chau, Minh H (Department: 2854)
Typewriting machines
Including control of format and selection of type-face by...
C400S076000, C358S001150, C358S001900
Reexamination Certificate
active
06805502
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to printing and more particularly to determining optimal batch sizes for processing jobs in a printing environment.
BACKGROUND OF THE INVENTION
Conventional printshops are organized in a fashion that is functionally independent of print job complexity, print job mix, and total volume of print jobs. Typically, related equipment is grouped together. Thus, all printing equipment is grouped and located in a single locale. Similarly, all finishing equipment is grouped and located in a single locale. In other words, conventional printshops organize resources into separate departments, where each department corresponds to a type of process or operation that is performed to complete a print job.
When a print job arrives from a customer, the print job sequentially passes through each department. Once the print job is completely processed by a first department, the print job gets queued for the next department. This approach continues until the print job is completed. Unfortunately, this conventional approach leads to significant time delays and increased work-in-progress and inventory costs.
SUMMARY OF THE INVENTION
The present invention addresses the above-described limitations of conventional approaches to processing print jobs in a printshop. In particular, the present invention provides an approach to optimally dividing a print job into sub-jobs or “batches.” The batches may then be separately processed so as to optimize the total turnaround time it takes to complete the processing of the print job. The present invention selects an optimal batch size for batches so as to reduce the total turnaround time for the print job. The optimal batch size may vary depending on whether a print job is processed as a serial sequence of operations without assembly operations or whether the print job involves assembly operations.
In accordance with one embodiment of the present invention, a method is practiced in a printing environment, such as a printshop or lean document factory, that has equipment for processing print jobs. In accordance with the method, the selected print job is received and divided into batches. The size of each of the batches is selected to substantially optimize the time period it takes for the selected print job to be fully processed. In many cases, the batch size may be selected to be purely optimal, however, in other instances, the batch size may be selected to be merely substantially optimal. The batches are processed separately and concurrently to complete processing of the print job.
In accordance with another aspect of the present invention, a method of optimizing the printing of a print job is performed in a printshop. Each operation that is required to complete the print job is identified. The print job is for a specified number of production items. A processing time required for each operation per production item is determined along with an inter-batch handling time that is required to switch between batches for each operation. A setup time for each operation is determined. Based on the processing times, the inter-batch handling times and setup times for the operators, the batch sizes of batches for the print job are determined.
In accordance with an additional aspect of the present invention, a method is practiced in a printshop such that a print job is represented as a sequence of interconnected nodes. Each node represents an operation, and the nodes are interconnected by edges representing workflow between operations. Paths are identified in the sequence of nodes and edges wherein the paths extend from an initial node (that has no predecessor nodes interconnected to it) to a last node (that has no successor nodes interconnected to it) in the sequence of interconnected nodes representing the print job. A critical path is identified among the paths. The critical path is the one that takes the longest amount of time to complete processing of a batch. The print job is divided into batches of given batch sizes for processing by the printshop. The batch sizes are chosen to optimize processing time for the critical path.
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Maitra Samaresh C.
Rai Sudhendu
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