Printing device for multiple recorders

A multiple recorder printing device for recording values of variable amounts on a moving recording tape in the form of consecutive symbols of the same or different colors includes a driven common drive means to both rotate the rotary printing head and move the printing head toward and away from the recording tape. The drive means permits rotation of the rotary printing head to be momentarily arrested during the period that a printing tip on the rotary printing head is in contact with the recording tape to assure clear printing on the recording tape without smudging.

BACKGROUND OF THE INVENTION 
This invention relates to a printing device for multiple recorders wherein 
values of variable amounts are recorded of a moving recording tape in the 
form of consecutive symbols, e.g. dots, in one or several colors. 
Printing devices of the type described herein include a rotary printing 
head which is adapted to be periodically moved toward and away from the 
recording tape and has a plurality of spaced printing tips or pins about 
its periphery. The printing head must be arranged such that while a 
printing tip is in contact with the recording tape, rotation of the 
printing head is arrested to avoid smudges. In the prior art this has 
required a complex drive unit including separate independent drive means 
for the rotating movement and for the lifting and lowering movement, 
respectively. A chopper bar or a rocker is provided to press down the 
printing head during the printing operation and a further mechanism is 
provided to lift the printing head following the printing operation. Thus, 
it will be appreciated that the drive mechanisms of prior art printing 
devices for multiple recorders have been relatively complex. 
It is an object of the present invention to provide a printing device for 
multiple recorders in which the drive mechanism for the printing head is 
substantially simplified with respect to both the lowering and lifting 
movement and the rotating movement of the printing head. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, the rotating movement of the 
printing head, as well as its lifting and lowering movements during the 
printing operation, are all directly derived from a continuously rotating 
drive rod. A cam plate supported on the drive rod controls a rocking lever 
by which the lifting and lowering movements of the printing head are 
affected. A pinion, also supported on the drive rod, and a series of gears 
also serve to rotate the printing head, provision being made for rotation 
of the printing head to be arrested momentarily during each succeeding 
printing operation.

DETAILED DESCRIPTION OF THE INVENTION 
Referring to the drawings, a pair of plates 2 and 3 are secured together in 
spaced relation by distance bushings 4 and bolts 5 to form a basic support 
structure. This support structure may be moved axially on a guide rod 6 
guided in a sleeve 7 firmly connected with the structure. The printing 
device is driven by rod 8 on which the structure is supported. The drive 
rod is formed preferably of three individual round section rods 9 held in 
position by pins 10 adjacent the ends of the rods. The three round section 
rods 9 are arranged to form a triangular configuration to simplify 
transfer of torque. 
A cam plate 11 which is driven by drive rod 8 contains on its periphery 
half as many recesses as there are printing tips on the periphery of the 
printing head to be described subsequently. A pinion 12 is mounted on the 
hub of the cam plate 11 with means 13 interposed between the cam plate 11 
and the pinion 12 permitting limited free relative rotation between the 
cam plate and the pinion. This means may be in the form of a projection 14 
on one part (cam plate 11 or pinion 12) which engages a limited recess 15 
of the other part (cam plate 11 or pinion 12) extending in the peripheral 
direction. 
Printing head 18 which is provided with spaced printing tips 19 about its 
periphery is attached to gear 17 which is driven through intermediate gear 
16 by pinion 12. A rocking lever 21 is pivotally supported on shaft 20 
which also rotatably supports the intermediate gear 16. One arm 20 of the 
rocking lever 21 carries a shaft 23 supporting the printing head 18. The 
other arm 24 of the rocking lever 21 includes a nose 25 adapted to engage 
the notches 26 of the cam plate 11. The rocking lever 21 may be biased in 
one pivotal direction by spring 27 if the printing device is arranged 
vertically as shown in the figures. The spring, however, is unnecessary if 
the printing device is arranged horizontally. 
A biased stop bolt 28 mounted on the arm 24 of the rocking lever 21 is 
adapted to cooperate with notches 30 of a stop plate 29 secured to gear 
17. The printing head 18 may be attached in the axial direction to the hub 
31 of the gear 17 by a snap seat 31a. Concurrent rotation of the printing 
head 18 and the gear 17 is assured by a pin 32 on the printing head which 
engages in a recess of the gear 17. With this arrangement the printing 
head 18 is easily exchanged for a different printing head. 
A recording tape 34 is guided via a roll 35 such that the printing tips 19 
on the printing head 18 will contact the recording tape 34 during each 
printing operation. 
It will be appreciated that the drive rod 8 serves both to rotate and to 
raise and lower the printing head 18. Upon rotation of the drive rod 8 the 
pinion 12 is rotated via cam plate 11 in the direction of arrow 36. This 
rotation is transmitted via intermediate gear 16 to gear 17 to rotate the 
printing head 18 in an anti-clockwise direction to position successive 
printing pins 19. Pivotal movement of the rocking lever 21, caused by the 
engagement of nose 25 with successive notches 26 of the cam plate 11, 
causes the printing head 18 to rise and fall during each printing 
operation. When the printing head 18 is moved toward the recording tape 34 
to effect printing, the pinion 12 is rotated by the gear 17 via the 
intermediate gear 16 because the spring bolt 28 has, shortly before, 
engaged a notch 30 in stop plate 29, i.e., the pinion 12 is running in 
advance of the drive rotation direction by the interposed means 13 
permitting limited relative rotation between the cam plate 11 and the 
pinion 12. As a result, the printing head 18 does not rotate during the 
actual printing when a printing tip 19 is in contact with the recording 
tape 34. To assure sufficient standstill time, a corresponding 
transmission ratio between the pinion 12 and gear 17 should be provided, 
i.e., at least a ratio of about 1:2. With the advance of the cam plate 12, 
the rocking lever 21 is pivoted to lift the printing head 18, the face of 
the notch 26 being pressed against the nose 25 of the rocking lever arm 
24. 
The printing head 18 is lowered under the action of spring 27. To break 
this lowering movement a tension spring 37 may be provided between the arm 
22 of the rocking lever 21, or an extension thereof, and the support 
structure 2,3 so that the contact pressure of the printing tips on the 
recording tape 34 may be reduced. 
The printing device may be provided with a pointer 39 which moves along a 
scale 40 simultaneously with displacement of the printing assembly. 
The printing device is so designed that it can be easily converted by 
interchanging the cam plate, the stop plate and the printing head to 
change the number of printing tips on the printing head, e.g. from six to 
twelve (6-12) printing tips. 
Preferably a substantial portion of the individual elements of the printing 
device may be made of lightweight plastic materials permitting quick 
setting time and a short dot sequence of the recorder. 
The present invention assures precisely synchronization between the raising 
and lowering of the printing head and the intermittent stopping of 
rotation of the printing head. The interposed means permitting limited 
relative rotation between the cam plate 11 and the pinion 12 insures that 
movement of the rocking lever 21 causes advance of the pinion 12 in the 
drive direction thus assuring the required short standstill time of the 
rotational movement of the printing head necessary during printing on the 
recording tape. The mechanical arrangement is simple and reliable.