(1) Field of the Invention
This invention relates generally to an improved offset collator. More specifically, this invention relates to a unique set finisher which incorporates the improved offset collator with an offset stapler.
(2) Description of the Prior Art
An important, but more general application of the offset collation method is disclosed in the previously cited related U.S. Application to Lamos. Lamos defines the terms "collate," "sort" and the difference between these terms, which are old in the prior art, and the new term "offset collate," which is defined for the first time in the related application.
Lamos recognized that the size of conventional collators is directly dependent on the number of discrete bins and the physical dimensions of the bins. Generally, the number of discrete bins determines the maximum number of sets that can be collated in a particular job. Consequently, the physical dimensions of the discrete bins, characterized by their height, width and depth determine the maximum sheet size that can be processed and the maximum number of sheets per discrete bin.
Lamos also recognized that since there is an overall physical size limitation, the solution in the prior art machines has been to strike a balance between the maximum number of sets that can be collated in a job and the maximum number of sheets that can comprise a set. Thus, in order to meet the physical size requirements, typical prior art machines have a capacity of about 20 sets comprising 100 sheets each, giving a total sheet capacity of 2,000.
The solution to the physical size problem, as disclosed in the cited related application, was the invention of offset collator and method for accomplishing same. The solution was to invent a unibin collator and develop the method of offset collation so that sheets to be offset collated would be alternately offset from each other in an arcuate transport path and then inserted, in the proper order, into a unibin receiving station. Consequently, this apparatus eliminated the need for discrete bins. Due to the use of a single bin, the offset collation method and an arcuate transport path, the apparatus was smaller in physical size than typical prior art collators, but yet had the same total sheet capacity thereof.
Nevertheless, although the Lamos apparatus made many improvements over the prior art, there is still a need for an improved offset collator that is still small in the prior art sense and provides an offset collator that is simpler in operation, more reliable and simpler in construction.
Additionally, in the previously cited related U.S. application to Lamos, it was recognized that there are other job requirements that cannot be satisfied by a collator having a plurality of discrete bins. The example given was for a collator having a maximum set capacity of 20 and a maximum sheet capacity of 100 sheets per set still giving a total sheet capacity of 2,000. Although it has been found in practice that seldom will there be the concurrent job requirement of more than 20 sets and more than 100 sheets per set, there are situations where the job will require the number of sets to be more than 20 and the number of sheets to be more than 100 sheets per set. It is clear from this example that the specified collator cannot process these jobs in the conventional sense.
Thus, as suggested in the referenced application to Lamos, there is a need to eliminate limitations in job flexibility characterized by the number of discrete bins and the sheet capacity of each bin. Consequently, it was recognized that there is a need for collators having substantially infinite job flexibility limited only by the total number of sheets in a job rather than the total number of sets in a job or the total number of sheets in a set.
There is an additional need in job flexibility in the case where offset collation is not required but sortation is required. Collating is defined herein as the insertion of a copy of an original in each of a plurality of sets. Sorting is defined herein as the directing of a sheet or sheets to a given place or rank according to kind or class, e.g., by stacking jobs so as to be demarcated from each other. Consequently, there is a need for an apparatus that not only can perform the offset collation method more reliably, but can also, in the same apparatus, perform a sortation operation without loss of speed, reliability or convenience.
Finally, there is an additional need in the prior art, as applied to offset collators, which has not been addressed by either Lamos in the referenced application, or as far as is known, anywhere else in the prior art. This additional need is offset stapling. It is defined herein as the stapling of offset collated sets or offset sorted jobs such that the offset collated sets or offset sorted jobs are maintained in their proper order and proper offset posture before, during and after the offset stapling process.
Consequently, there is not only a need in the prior art for an improved offset collator that can also operate in an offset sorting mode, but an additional need for an offset stapling station cooperating with the improved offset collator to staple the finished offset collated sets or offset sorted jobs, thereby providing completed finished sets or jobs.