Printing Member Selector And Drive Means

Abstract

A printing mechanism for printing a selected symbol combination or permutation code on an item of mail or the like. The mechanism includes a number of movable printing strikers adjacently arranged in accordance with the particular geometrical configuration of the code. The strikers are mechanically biased in a rest position and are selectively driven into a printing position by a drive and selection mechanism associated with each. According to the invention this drive and selection mechanism includes a sleeve coupled to a common "guide member" which moves between a selecting position and an operating position; an elongated pusher, movably arranged within the sleeve; an electromagnet arranged to selectively apply an attractive force against one end of the pusher; a catch, which is hinged to the sleeve, for driving the associated striker, when in a "catch position," from the rest position to the printing position when the sleeve is moved by the guide member from the selecting to the operating position; and a device coupling the other end of the pusher to the catch for moving the catch into and out of its catch position in response to the movement of the pusher relative to the sleeve.

Description

BACKGROUND OF THE INVENTION

The present invention relates to a printing mechanism for applying a permutation code to a symbol carrier; that is, for applying a distinguishing mark which contains a characteristic group of symbols or code elements selected from a total number of possible code elements. Such a printing mechanism may be used, for example, to apply machine readable symbols to items of mail which are to be automatically sorted.

Printing mechanisms suitable for this purpose are known in the art. One such apparatus, which is described in the German published Pat. application DAS 1,125,212, has a plurality of strikers, equal in number to the total number of code elements, arranged next to each other in accordance with the particular geometrical arrangement of the code elements. Each striker, which is elongated in shape, is provided with a printing stamp at one end and is slidably mounted so that it can be moved against the force of a return spring from a rest position into a printing position. Particular ones of the strikers are selected by a mechanism comprising a like number of correspondingly arranged latches which may be selectively shifted into a locked (catching) position or a nonlocked (empty) position by means of an electromagnetically actuated device. Finally a guide member is also provided to move the selection mechanism during each printing cycle from a rearward position (selecting position) to a forward position (operating position). Those printing strikers which are selected by the latches of the selection mechanism are consequently moved to their printing position to form the characteristic symbol.

As an improvement upon the particular printing mechanism disclosed in the above-mentioned German printed patent application, it has been suggested that each selection mechanism latch exhibit a stop face which assumes such a position, relative to the rear face of its associated printing striker when in the catch position that it abuts this rear face as the guide element moves the latch toward the operating or printing position. Those latches having their stop faces in the catch position therefore force their associated printing strikers to move with them. When a latch is in the nonlocked (empty) position, it allows the rear face of the printing striker to move past its stop face so that no symbol will be printed. This suggested type of selection mechanism has the advantage, with respect to the corresponding mechanism disclosed in the above mentioned German printed patent application, that it permits the printing strikers to be heated as necessary without heating any of the parts of the selection mechanism.

SUMMARY OF THE INVENTION

An object of the present invention is to provide an improved printing mechanism of the type described above which permits the individual printing strikers to be heated.

This object, as well as other objects which will become apparent in the discussion that follows, is achieved, according to the present invention, by providing a hinged hook or catch to serve as the latch of the selection mechanism. This hook is made with an abutment surface that can be swung into and out of the path of the striker as it is moved toward the striker.

More particularly, therefore, the present invention resides in the construction of the drive and selection mechanism associated with each printing striker. According to the invention this drive and selecting mechanism includes a sleeve coupled to the common guide member that moves between the selecting position and the operating or printing position. An elongated pusher is movably arranged within the sleeve and an electromagnet is provided to selectively apply an attractive force against one end of the pusher. The hook or catch, which is hinged to the sleeve so as to drive the associated striker when in its "catch position," moves the striker from its rest position to its printing position when the sleeve is moved by the guide member from the selecting to the operating position. Finally, the drive and selection mechanism is provided with a device coupling the other end of the pusher to the hook (catch) for moving the hook into and out of its catch position in response to the movement of the pusher relative to the sleeve.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a portion of a printing mechanism according to the preferred embodiment of the present invention. Included in the figure are a single printing striker and its associated drive and selection mechanism. A guide member is shown in its selecting position.

FIG. 2 is a cross-sectional view through a portion of the printing mechanism of FIG. 1 showing two printing strikers and the drive and selection mechanism associated with each. The guide member is shown in this figure in a position intermediate between the selecting and the operating positions.

FIG. 3 is a cross-sectional view through a portion of the printing mechanism of FIG. 1 showing two printing strikers and the drive and selection mechanism associated with each. The guide members are shown in this figure in its operating position.

FIG. 4 is a cross-sectional view of the drive and selection mechanism of a single printing striker. The catch member of this mechanism is illustrated in the empty, or nonlocked position.

FIG. 5 is a cross-sectional view of the drive and selection mechanism of a single printing striker. The catch member of this mechanism is shown here in the catching or locking position.

FIG. 6 is a cross-sectional view taken along the line C--D of FIG. 5. FIG. 6 shows the lines of cross section A-B of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENT

The preferred embodiment of the printing mechanism according to the present invention will now be described in detail with reference to FIGS. 1--6 of the drawings. As is there shown, the printing mechanism comprises a plurality of printing strikers 1 mounted between two guide plates 2 and 3 of a housing. These printing strikers are located next to each other in the geometrical arrangement required for the particular code to be printed. The strikers are elongated in shape and are mounted in such a way as to be moveable in the direction of their longitudinal axes from a normal or rest position (FIG. 1) to a printing position (FIG. 3, top). In the latter position they are pressed against the item 5 to be printed. Each printing striker is maintained in its normal or rest position by a return spring 4 which acts against a collar 1'.

If the printing strikers 1 are to be heated, the above-mentioned housing is also provided with heating apparatus, not shown. In this case it is possible, for example, to arrange a heating element in a suitable cavity or cavities in the guide plate 2, which is then constructed with correspondingly greater thickness.

On a common axis with each printing striker is arranged a pusher 6 which is mounted within a guide member consisting of guide plates 7 and 8. The pusher 6 may be shifted in the axial direction with respect to the guide member between a forward position (FIGS. 1 and 4; FIGS. 2 and 3, bottom) and a rearward position (FIG. 5; FIGS. 2 and 3, top). The pusher 6 is not mounted directly in the guide member 7 and 8, as would actually be possible, but in a separate sleeve 9 which is also axially moveable with respect to the guide element. As will be explained in detail below, this sleeve 9 can retreat during a particular operational stage of the printing cycle against the force of an equalizing spring 10 in the guide member 7 and 8; that is, the sleeve can be shifted back (toward the right as shown in FIG. 3, top). One end of the equalizing spring 10 abuts against the guide plate 8 while the other end acts upon a collar 11 of the sleeve 9. When the sleeve is in the rest position (FIGS. 1 and 2; FIG. 3, bottom) this collar 11 lies against the guide plate 7 of the guide member.

The pusher 6 carries a head 6' at its forward end as shown in FIGS. 4--6. This head 6' is of larger diameter than the pusher 6 and is provided with a slot 12 which is bridged by a pin 13. In order to accommodate the head 6' the forward portion of the bore of the sleeve 9 is made with a correspondingly greater diameter. The rearward movement of the pusher 6 is limited by the abutment of the head 6' against the flank of the smaller diameter portion of the bore of the sleeve 9 (FIGS. 5 and 6). The forward movement of the pusher 6 is limited by the abutment of a shapring 14, which surrounds the pusher, against the rearward end of the sleeve 9 (FIGS. 1 and 4; FIGS. 2 and 3, bottom).

The forward portion of the bore of the sleeve 9, which contains the pusher head 6', opens into a housing which is formed in part by two plates 9', Between these plates is arranged a hook or catch 15 which serves as a selection member for the associated printing striker 1.

The short forward portion of the catch 15 forms an abutment surface 15'. Its longer rearward portion is provided with a longitudinally extending opening 16 (FIG. 6). Both of the right hand ends of this long portion of the catch 15 are hinged in a seat 9" in the sleeve member 9. The catch 15 is swiveled by the forward and rearward movement of the pusher 6 so that its abutment surface 15' will move between a noncatch position (FIG. 4) and a catch position (FIG. 5). When in the latter position; the surface 15' will abut the rearward end of the striker 1 and drive it into the printing position.

The catch 15 is coupled to the pusher in the illustrated preferred embodiment by a plate 17 which forms a doubled-armed lever and by a tension spring 18. The plate or lever 17 is rotatably mounted on an axle 19 within the sleeve 9 and has a slot 17' which receives the pin 13 that passes through the head 6' of the pusher 6. The tension spring 18 is located in the opening 16 of the catch 15. The forward end of the spring is attached to the catch while the rearward end is connected to the lever 17. The point of connection between the spring and the lever 17 is so situated, with respect to the seat 9", that the lever 17, spring 18 and the catch 15 form a bistable tilting system.

The short forward portion of the catch 15 which forms the abutment surface 15' is made somewhat wider than the long portion that is arranged between the two plates 9' and projects laterally outward in a recess in each of the forward edges of the plates 9'. When the abutment surface 15' of the catch 15 is in the lower position, therefore, it lies flat against these recessed edges of the plates 9' (FIGS. 5 and 6). In the other stable position of the catch 15--that is, in the noncatch position--the forward short portion of the catch 15 lies against the upper projecting edges of the recesses of the plates 9' (FIG. 4).

In some cases it may be advantageous in practice to construct the long portion of the catch 15 as a flat spring which is so dimensioned as to be slightly squeezed or tensioned in one or both of the stable positions.

In order to control the striker-selecting movements of the pushers 6, a plurality of electromagnets 21 are rigidly mounted in a plate 20 behind the guide plates 7 and 8 so as to selectively apply attractive forces to armatures 6" which form the rearward end of each pusher 6.

The guide plates 7 and 8 are moved back and forth during each printing cycle from a rearward position (selecting position, FIG. 1) to a forward position (operating position, FIG. 3). This movement can be effected by any suitable means known in the art such as a cam drive (not shown).

The preferred embodiment of the printing mechanism, shown and described, operates in the following manner. When the guide plates 7 and 8 move into the selecting position (FIG. 1) the armatures 6" of each of the pushers 6 abut against their associated electromagnets 21 or against the plate 20. This causes all the pushers to move into their forward positions thus driving all the selection members (catches) 15 into their noncatch or upper stable positions (FIG. 4). Certain ones of the electromagnets 21 will next be excited in correspondence with the desired code; the remaining electromagnets will receive no current. As a result, when the guide plates 7 and 8 are then moved forward (FIG. 2) toward the operating position all of those pushers 6 which are associated with an excited electromagnet will be drawn toward their rearward positions (FIG. 2, top) causing the corresponding selecting members (catches) 15 to drop into their catch positions (FIGS. 2 and 3, top; FIG. 5).

As the guide plates 7 and 8 continue to move forward toward the operating position (FIG. 3), the abutment surfaces 15' of those selection members which are in the catch position (FIG. 3, top) will abut the rear faces of the associated printing strikers 1 and drive them forward into their printing position. Those abutment surfaces 15' of the catches 15 which have remained in the noncatch positions (FIG. 3, bottom) will simply move past on one side of the rear faces of their associated printing strikers 1.

During the printing process the rear surface of the head 6' of the pusher 6 abuts against the forward edge of the smaller diameter portion of the bore of the sleeve 9. When this occurs, the sleeve 9, as well as the catch 15 and the printing striker 1, can retreat with respect to the guide plates 7 and 8 against the force of the spring 10 to equalize any unevenness in the item 5 on which the symbol is printed.

It will be understood that the above description of the present invention is susceptible to various modifications, changes and adaptations.

Claims

We claim:

1. Printing mechanism for printing selected symbol combinations on a carrier such as an item of mail or the like, said mechanism comprising, in combination:

a. a housing;

b. a plurality of striker means, arranged in said housing, for printing a symbol on such carrier, said striker means being movable with respect to said housing between a rest position and a printing position;

c. a plurality of return springs, each associated with one of said striker means, for biasing said striker means in said rest position;

d. a guide member which is movable with respect to said housing between a selecting position and an operating position; and

e. a plurality of drive means each associated with one of said striker means and arranged in said guide member, for driving selected ones of said striker means from said rest position to said printing position when said guide member is moved from said selecting position to said operating position, each drive means including:

1. a sleeve member coupled to said guide member;

2. a pusher movably arranged within said sleeve member and having two ends;

3. an electromagnet rigidly connected to said housing, for selectively applying an attractive force against one end of said pusher;

4. catch means, which is hinged to said sleeve member, for driving the associated one of said striker means from said rest position to said printing position when said sleeve member is moved by said guide member and said catch means is in a catch position, and for leaving said striker means in said rest position when said sleeve member is moved by said guide member and said catch means is out of its catch position; and

5. means, coupling the other end of said pusher to said catch means, for moving said catch means into and out of said catch position in response to the movement of said pusher with respect to said sleeve member, whereby selected ones of the plurality of pushers may be moved with respect to the plurality of sleeves by excitation of corresponding ones of the plurality of electromagnets during the time that said guide member is moved from said selecting position to said operating position, thereby to move selected ones of said striker means from said rest position to said operating position.

2. The printing mechanism defined in claim 1, wherein said coupling means includes a double armed lever, hinged in said sleeve member, said lever being arranged to swivel in response to the movement of said pusher.

3. The printing mechanism defined in claim 2, wherein said pusher is arranged to move in a linear direction.

4. The printing mechanism defined in claim 3, wherein said coupling means further includes spring means for transmitting the swivel motion of said lever to the movement of said catch means.

5. The printing mechanism defined in claim 4, wherein said spring means is connected between said lever and said catch means, the points of connection of said spring means and the point at which said catch means is hinged to said sleeve member being arranged, relative to each other, so as to form a bistable tilting system, whereby said catch means is in a stable position both when in and when out of said catch position.

6. The printing mechanism defined in claim 5, wherein said spring means is a tension spring.

7. The printing mechanism defined in claim 1, further comprising means for spring coupling said sleeve member to said guide member, thereby to compensate for differences in the thickness of the carrier upon which the symbols are printed.