Printing – Stenciling – Rotary machines
Reexamination Certificate
1999-08-30
2001-05-29
Hilten, John S. (Department: 2854)
Printing
Stenciling
Rotary machines
C101S484000, C101S232000, C271S256000, C271S258020, C400S637100, C400S636000, C400S708000
Reexamination Certificate
active
06237485
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a stencil printer, and more particularly to control of paper supply to a stencil printer.
2. Description of the Related Art
There has been known a stencil printer in which a stencil master is wound around a printing drum and a printing paper is supplied between the printing drum and a press roller which are rotated in contact with each other so that ink supplied inside the printing drum is transferred to the printing paper through the imagewise perforations in the stencil master while the printing paper is conveyed pinched between the printing drum and the press roller.
In such a stencil printer, it is required that the printing paper is supplied between the printing drum and the press roller so that the printing paper is accurately positioned with respect to the stencil master wound around the printing drum. For this purpose, in a conventional stencil printer, paper supply, paper conveyance, printing and paper discharge are effected for each rotation of the printing drum by use of gear mechanisms and/or cam mechanisms which are driven by rotation of the printing drum.
More specifically, the conventional stencil printer comprises a primary paper supply section which feeds out printing papers one by one from a stack of printing papers on a paper supply table, a secondary paper supply section which is provided with a timing roller pair which feeds the printing paper received from the primary paper supply section to between a printing drum and a press roller, a printing section which supplies ink from an ink supply section inside the printing drum to the printing paper which is conveyed pinched between the printing drum and the press roller so that the ink is transferred to the printing paper through a stencil master, and a paper discharge section which discharges the printing paper from the printing drum after printing. A series of actions, paper supply, paper conveyance, printing and paper discharge, are timed on the basis of a detected angular position of the printing drum and a detected position of the printing paper.
In such a conventional stencil printer, printing on one printing paper is done in one rotation of the printing drum irrespective of the length of the printing paper (the dimension as measured in the direction of conveyance of the printing paper). Accordingly, the permissible maximum length of a printing paper basically depends on the circumference of the printing drum, and since the printing actions including paper supply, paper conveyance, printing and paper discharge are controlled detecting the angular position of the printing drum and the position of the printing paper, the permissible maximum length of a printing paper is generally slightly smaller than the circumference of the printing drum.
Recently, there has been a demand for a stencil printer which can print on printing papers which are longer than the permissive maximum length (will be referred to as “overlong printing paper”, hereinbelow). In such a case, printing is made only on a part of the printing paper. When printing is to be made on such overlong printing papers, the printing drum completes one rotation before the printing paper is completely discharged from the printing drum, and accordingly, the paper supply action for the next printing paper must be initiated before the preceding printing paper is completely discharged from the printing drum. That is, supply of the next printing paper must be initiated while the trailing end portion of the preceding printing paper is still between the pair of timing rollers or between the printing drum and the press roller.
In the conventional stencil printers, the primary and secondary paper supply sections are generally arranged to convey the printing paper at a speed higher than that at which the printing paper is conveyed by the printing drum and the press roller, and accordingly when supply of a next printing paper is initiated while the trailing end portion of the preceding printing paper is still between the pair of timing rollers or between the printing drum and the press roller, the leading end portion of the next printing paper can collide with the trailing end portion of the preceding printing paper, thereby causing paper jam and the like.
SUMMARY OF THE INVENTION
In view of the foregoing observations and description, the primary object of the present invention is to provide a stencil printer which can continuously make print on overlong printing papers without trouble.
In accordance with the present invention, there is provided a stencil printer comprising
a printing drum which is rotated bearing thereon a stencil master,
a press roller which is pressed against the printing drum,
a paper supply means which supplies a printing paper to between the printing drum and the press roller so that the printing paper is conveyed pinched between the printing drum and the press roller, and
a paper supply control means which controls the paper supply means so that the paper supply means supplies the printing paper to between the printing drum and the press roller at a first predetermined angular position of the printing drum for each rotation of the printing drum,
wherein the improvement comprises that
a paper length input means generates a paper length signal representing that the printing paper is an overlong printing paper which is larger than a standard length in a length as measured in the direction of conveyance of the printing paper, and
said paper supply control means controls the paper supply means, when the paper length input means generates the paper length signal, so that the printing paper supplied next by the paper supply means does not collide with the printing paper under printing.
In this specification, the term “standard length” means the permissible maximum length of a printing paper which can be printed by one rotation of the printing drum and basically depends on the structure of the printing drum, the paper supply mechanism, the paper conveying mechanism and the like.
The paper supply control means may control the paper supply means in any manner when the paper length input means generates the paper length signal provided that the printing paper supplied next by the paper supply means does not collide with the printing paper under printing. For example, the paper supply control means may control the paper supply means when the paper length input means generates the paper length signal so that the paper supply means does not initiate paper supply until the preceding printing paper is completely discharged, so that the paper supply means initiates the paper supply later than the normal timing, or so that the paper supply means conveys the next printing paper at a speed lower than that at which the preceding printing paper is conveyed during printing.
In one embodiment, the paper supply control means inhibits the paper supply means from supplying the next printing paper while the printing paper under printing is being conveyed through the printing drum and the press roller.
In another embodiment, said paper supply means comprises a primary paper supply section which feeds out the printing paper from a stack of the printing papers at a fourth predetermined angular position of the printing drum and a secondary paper supply section comprising a pair of timing rollers which supplies the printing paper fed from the first paper supply section to between the printing drum and the press roller at the first predetermined angular position of the printing drum, and
said paper supply control means inhibits the primary paper supply section from feeding out the next printing paper at the fourth predetermined angular position of the printing drum while the printing paper under printing is being conveyed through the pair of timing rollers.
When the paper supply means comprises the timing rollers, the paper length input means may comprise
a paper detecting means which detects whether the printing paper exists near the pair of timing rollers at a predetermined timing, and
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Grohusky Leslie J.
Hilten John S.
Nixon & Peabody LLP
Riso Kagaku Corporation
Studebaker Donald R.
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