U.S. patent number 3,817,365 [Application Number 05/365,130] was granted by the patent office on 1974-06-18 for automatic print head shifting device.
This patent grant is currently assigned to Triumph Werke Nurnberg A.G.. Invention is credited to Norbert Zimmermann.
United States Patent |
3,817,365 |
Zimmermann |
June 18, 1974 |
AUTOMATIC PRINT HEAD SHIFTING DEVICE
Abstract
Automatic shifting mechanism is provided to shift a pin matrix
type head normally positioned closely spaced from a printing plane
during printing to a retracted position away from the printing
plane during carriage return movement of a carriage supporting the
printing head. Movement of the printing head from printing and
retracted positions is controlled by carriage limit position.
Inventors: |
Zimmermann; Norbert (Nurnberg,
DT) |
Assignee: |
Triumph Werke Nurnberg A.G.
(Postfach, DT)
|
Family
ID: |
5853093 |
Appl.
No.: |
05/365,130 |
Filed: |
May 30, 1973 |
Foreign Application Priority Data
Current U.S.
Class: |
400/59;
101/93.04; 101/93.05 |
Current CPC
Class: |
B41J
25/3086 (20130101); B41J 25/308 (20130101) |
Current International
Class: |
B41J
25/308 (20060101); B41j 009/20 () |
Field of
Search: |
;197/1R,18,60,66,68
;101/93C,94 ;178/25 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
Primary Examiner: Pulfrey; Robert E.
Assistant Examiner: Eickholt; E. H.
Claims
The invention claimed is:
1. In a pin matrix printer having a printing plane, a pin matrix
housing and a carriage supporting said housing mounted for movement
relative to said printing plane in writing and carriage return
directions,
means on said carriage for releasably holding said housing in
printing position close to said printing plane to permit pins
supported therein to print against a record located in front of
said printing plane, said means being operative on release to
retract said housing away from said printing plane,
other means responsive to a carriage return signal for releasing
said holding means,
and further means cooperating with said means on said carriage for
restoring said matrix housing to said printing position on return
of said carriage to an initial beginning of line position.
2. In a pin matrix printer as recited in claim 1, said means on
said carriage for releasably holding said matrix housing comprising
lever means pivoted on said carriage and connected to said housing,
spring means biasing said lever in a direction to retract said
housing, and latch means for holding said lever against movement by
said spring means.
3. In a pin matrix printer as recited in claim 2, said other means
comprising a latch member, a spring biasing said latch member to
latching position, and means responsive to movement of said
carriage to an end of line position to operate said latch member
against its spring bias to release said lever means.
4. In a printer as recited in claim 3, said further means including
an abutment on said lever means, and a frame stop positioned to
engage said abutment when said carriage is returned to force said
lever means to latched position.
Description
This invention relates to pin matrix printers; more particularly,
it relates to an automatically operable shifting device for
controlling the spacing between a pin matrix print head and a
printing plane, and, specifically, it relates to a shifting device
operable to retract the printing head mounted on a movable carriage
to an inactive position spaced from the printing plane incident to
carriage return movement and to restore the print head to a
printing position closely adjacent the printing plane on return of
the carriage to a beginning of line position.
Pin type print heads, because of the short stroke of the pins to
effect printing, require that the spacing of the print head from
the printing plane be kept uniform to assure even density of print
from character to character. Previously, such print heads have been
associated with devices for controlling the spacing of the print
head from the printing plane according to the thickness of the
information bearing record. This has been accomplished by sensing
devices, for example, by heads resiliently spring biased toward the
printing plane or associated rollers mounted on the printing head
which ride against the record and cause the spring biased head to
retract according to record thickness sensed by the roller. Sensing
devices of this type which bear against the paper interposed
between print head and printing plane are apt, at the high return
speeds of the carriage supporting the print head, to damage the
paper and/or an inked ribbon and otherwise render illegible printed
information.
In accordance with this invention, the above problem is alleviated
in the provision of a print head shifting device operable to
increase the spacing between print head and printing plane during
return movement of a carriage supporting the print head to avoid
frictional contact between print head and record. In one
embodiment, the print head is associated with a spring biased lever
acting normally to retract the print head from a normal print
position closely adjacent the printing plane. Means are provided to
automatically urge said lever against its spring bias and to latch
it when a carriage supporting the print head reaches a beginning of
line position thereby to hold the print head in print position.
Further, means are provided to release the latch incident to a
carriage return command issuing when the carriage has moved to a
particular print location or on receipt of a prearranged signal
following printing of selected information in a line.
Accordingly, an object of the invention is to provide an automatic
system for varying the spacing between a pin matrix head and a
print plane according to the direction of movement of a carriage
supporting said print head.
Another object of the invention is in the provision of a system for
normally releasably holding a print head in printing position
closely adjacent a printing plane during movement of a carriage
supporting the print head in a printing direction and for releasing
said print head for movement away from said printing plane incident
to and over the interval of a carriage return movement to a
beginning of line position.
Other objects and many of the attendant advantages of this
invention will be readily appreciated as the same becomes better
understood by reference to the following detailed description when
considered in connection with the accompanying drawing in which
like reference numerals designate like or corresponding parts
throughout the figures thereof and wherein;
FIG. 1 is an elevational view showing a carriage supported pin
matrix print head in a retracted position with the carriage moving
in carriage return direction; and
FIG. 2 is an elevational view similar to FIG. 1 showing the print
head in printing position closely adjacent a printing plane after
movement of the carriage to a beginning of line position.
Referring now to the drawing wherein like reference numerals
designate like or corresponding parts throughout the several views,
there is shown in FIG. 1 a carriage 3 which is supported for
movement relative to a printing plane 4 on a pair of parallel guide
rails 5 parallel to the printing plane 4. The carriage 3 pivotally
supports a lever generally designated by reference numeral 6 as at
7 which has a rightwardly extending arm 8 the end of which is
coupled as by a pin 9 to the housing of a pin matrix print head
generally designated by reference numeral 11. The lever 6 also has
a downwardly extending arm 12 whose end is formed with a latching
recess 13 adapted to cooperate with a latching pin 14 on the end of
a horizontal latch member or bar 15. The other end of the latch
member 15 is pivotally mounted on the carriage as at 16 and a
spring 17 connected to an anchor 18 on the print head and to latch
member 15 intermediate its ends normally tends to bias the latch
member 15 upwardly into engagement with the end of lever arm 12.
The lever 6 is normally urged clockwise by a torsion spring 19
wrapped about pivot 7 and having an end coupled to lever arm 12 as
at 21. Thus, as shown in FIG. 1, the lever 6, since its recess 13
is to the left of the latching pin, is not latched by the latch
member 15, and, through its arm 8, retracts the print head 11 away
from the printing plane in the direction of arrow I a sufficient
distance to allow free carriage return movement of the carriage and
head by suitable conventional means without the print head
contacting a record positioned between the end of the print head
and the printing plane to receive printing.
As the carriage moves in the direction of arrow II or to the left
as viewed in FIG. 1, an abutment or pin 22, secured to the lever
arm 12 and extending upwardly from the plane of the drawing, will
encounter a frame abutment 23 in its path defining a beginning of
line or left margin position with the result that the lever 6 will
be moved counterclockwise, cam the latch member counterclockwise,
and be held by cooperative engagement of the latching pin 14 of the
latch member and the latching recess on the end of lever arm 12, as
shown in FIG. 2. This movement of the lever 6 against the bias of
its spring 19 will move the print head 11 in the direction of arrow
III (FIG. 2) to print position closely adjacent the printing plane
as illustrated in FIG. 2. Printing of a line of characters by pins
in the print head may be accomplished with the carriage moving in
the direction of arrow IV under control of suitable motive or
escapement mechanism. On some selected point in the line of print a
carriage return command will occur and function to release lever 6
from latch member 15 as by rocking the latch member
counterclockwise about its pivot with the result that the parts
will reassume their FIG. 1 position until again the carriage
returns to beginning of line position. In one embodiment, the
carriage return command may be a signal pulse that may be applied
to momentarily energize an electromagnet 25 located to attract the
latch member directly or through an armature (not shown) and rotate
it to release lever 6.
The objects of the present invention to regulate the distance
between the printing head and the printing counterbearing are
achieved by means of simple, readily produced components enabling
the distance between the printing head and the printing plane to be
increased for the return motion of the carriage so that damage to
the information carrier by the print head cannot occur even when
the return motion of the carriage takes place at a high rate of
speed.
The present invention is not limited to the embodiment described
and shown in the drawing, modifications being possible within the
scope of the idea behind the invention. For example, instead of the
detent pin of the latch member 15, the latch member 15 may be
provided with a recess into which the lever arm 12 snaps. It is
also possible to design the lever 6 itself so as to perform the
function of the pin 22 at the end of lever arm 12. Finally, the
disengagement of the lever 6 from the latch member 15 may also be
triggered by purely mechanical means rather than by the magnet, for
instance, in response to the carriage encountering the right margin
setter usually present in such printing systems together with an
appropriate design of the latch member 15.
* * * * *