1. Field of the Invention
The invention relates to offset-type printing mechanisms for high-speed printing of magnetic ink character recognition (MICR) symbols which use a conventional spool of print ribbon.
2. Background Art
Offset-type printing mechanisms typically require that depleted spools of ribbon media be replaced at regular integrals by less-skilled personnel. Because such printing mechanisms typically include spring tensioner, guide and locking elements to ensure correct installation, location and control of the ribbon and ribbon replacement mechanisms must be designed with an eye to swift, self-evident and foolproof ways of replacing ribbon for minimum downtime.
Existing approaches fail to address all of these concerns. Existing approaches typically require operators to learn and remember a specific routine of steps for ribbon replacement, deviation from which will lead to problems.
For the foregoing reasons, there is a need for an improved ribbon spool lock assembly for use in offset-type printing mechanisms.
It is an object of the invention to provide an improved ribbon spool lock assembly in which the operator can only replace the ribbon by a series of steps which are designed-into the mechanism and which cannot be deviated from.
The invention involves mechanisms designed in such a way that ribbons cannot be replaced incorrectly. The invention also involves mechanisms which temporarily displace other machine elements which would interfere with ribbon replacement.
In carrying out the invention, a ribbon spool lock assembly for use in a print mechanism is provided. The print mechanism is of the type in which ribbon spools are required to be locked in place radially when the mechanism is functioning. The invention uses a positive radial spool lock for this purpose. This lock must be opened by some operator interaction when ribbon is to be replaced.
The print mechanism also includes a pivoting ribbon tension arm, which applies tension to the ribbon for printing-related purposes. The tensioner arm must be pivoted out of its normal operating position when ribbon is to be replaced, and held out of position during the replacement process. Yet the tensioner arm must be returned to the normal operating position before normal printing recommences.
According to the invention, a rotating locking hub is built into the side of the printing mechanism. The locking hub includes a locking feature that protrudes into the printing mechanism in such a way as to radially lock the ribbon spool in the correct position for printing.
A preferred approach employs a pair of linked rotating hubs built into each side of the printing mechanism. The locking hubs include locking features that protrude into the printing mechanism in such a way as to radially lock the ribbon spools in the correct positions for printing. In this way, each end of each ribbon spool is radially locked.
Further, in the preferred approach, the locking hubs are pivoted into a released or unlocked position by way of two pivoting lock arms. These lock arms may be designed to be operated with the operator's fingers. When in the released position, the linked locking hubs are pivoted out of the exit/entry path of the ribbon spools. This allows the ribbon spools to be removed and replaced.
In another comprehended feature of the invention, the pivoting lock arms contain additional features which interlock with the pivoting ribbon tensioner arm to automatically pivot and lock the tensioner arm to its load ribbon position.
Accordingly, in operation of the preferred embodiment of the invention, an operator cannot remove ribbon spools until the locking hubs are rotated to the correct released positions by means of the two pivoting lock arms. This causes the tensioner arm to rotate to the correct load ribbon position. Once the operator threads the new ribbon through the printer mechanism and initially tensions the printer system manually or by some other automated ribbon advanced feature, the pivoting ribbon tensioner arm is caused to rotate forward and automatically release the two pivoting lock arms. At this point, springs cause the linked locking hubs to rotate back to the correct lock position for printing.
It is appreciated that the preferred embodiment contains features which lock both ribbon spools (supply and takeup) with a pair of linked locking hubs and two pivoting lock arms. Various changes may be made in the implementation of the invention according to the needs of a particular design of a printing mechanism. For example, locking hubs could be used to secure only one spool of ribbon. Further, for example, the entire system may be operated automatically rather than by manual operation, in which case the interlocking of various parts in their correct positions would be by sensors and electronic control rather than by physical, mechanical interlocks.
As shown in
With continuing reference to
In accordance with the invention, system 10 may incorporate a printing mechanism including the improved ribbon spool lock assembly. For example, encoder 32 or encoder 36 could include a printing mechanism including the improved ribbon spool lock assembly.
Printing mechanism 50 is equipped with a pair of ribbon spools, and requires that the ribbon spools be locked in position radially when printing mechanism 50 is functioning. The locking function is provided by a positive radial spool lock which must be opened by some operator interaction when ribbon is to be replaced.
Driving shaft part 114 includes gear drive means 120, and first bearing/locating surface 122. The hand-separable function is provided by a push-and-turn arrangement 136 built into the two-piece shaft assembly 100. As shown, end 130 of cooperating shaft part 116 extends through aperture 124 of driving shaft part 114, and this cooperation provides the locking mechanism for locking the shaft parts together.
Cooperating shaft part 116 includes second bearing/locating surface 132. Spring means enclosed within shaft part 116 provide both the locking force for the push-and-turn function and the necessary lateral force to clamp the two shaft halves onto the ribbon spool to eliminate lateral tolerance variations.
Shaft assembly 100 locates the ribbon spool radially and in all three axes of translation and provides the necessary rotational bearing and locating surfaces to position the ribbon spool correctly in the printing mechanism 50. In the printing mechanism 50, the shaft allows the ribbon spool to rotate to unwind/rewind correctly, and provides gear drive means to drive/retard the rotating ribbon spool.
It is appreciated that shaft assembly 100 is exemplary, and a variety of shaft assemblies could be used in combination with a print mechanism having a ribbon spool lock assembly made in accordance with the invention.
With continuing reference to
Printing mechanism 50 includes side plates 74. A pair of linked rotating hubs 76 are built into each side 74 of printing mechanism 50. Locking hubs 76 include locking features 78 that protrude into print mechanism 50 in such a way as to radially lock the ribbon spools in the correct positions for printing. In this way, each end of each installed ribbon spool is radially locked. Slots 80 and 82 are for receiving the ribbon spools.
Locking hubs 76 are pivoted into a released or unlocked position by way of two pivoting lock arms 84. Lock arms 84 may be designed to be operated with the operator's fingers. When in the released position, the linked locking hubs 76 are pivoted out of the exit/entry path (slots 80 and 82) of the ribbon spools. This allows the ribbon spools to be removed and replaced.
In the preferred embodiment, pivoting lock arms 84 include additional features which interlock (interlocking is shown in
Rotating hubs 76, with locking features 78 that protrude into printing mechanism 50, are linked by link 88. As shown, locking hubs 76 are in the normal operating positions in
In
In operation of the preferred embodiment of the invention, an operator cannot remove ribbon spools until locking hubs 76 are rotated to the correct released positions (
Although the preferred embodiment is illustrated with features that lock each side of each ribbon spool (supply and takeup) by utilizing a pair of linked locking hubs on each side of printing mechanism 50, together with two pivoting lock arms 84, other implementations are possible. Appropriate locking hubs could be used to secure only one spool of ribbon. As well, it is possible that the entire system may be operated automatically rather than by manual operation, in which case the interlocking of various parts in their correct positions would be by sensors and electronic control rather than by physical, mechanical interlocks.
While embodiments of the invention have been illustrated and described, it is not intended that these embodiments illustrate and describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention.
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