U.S. patent number 3,867,882 [Application Number 05/352,570] was granted by the patent office on 1975-02-25 for apparatus for printing labels directly onto packages, containers and the like.
This patent grant is currently assigned to Houston Engineering Research Corporation. Invention is credited to Erick L. Ahlgren, Arthur H. McMorris, Joseph L. Schweppe.
United States Patent |
3,867,882 |
Ahlgren , et al. |
February 25, 1975 |
APPARATUS FOR PRINTING LABELS DIRECTLY ONTO PACKAGES, CONTAINERS
AND THE LIKE
Abstract
An apparatus for placing labels on cartons, containers and bales
which are subjected to having profile altering straps, bands, or
framing members on the exterior. The apparatus includes a probe
which finds the side of the carton and positions a probe relative
to the surface. When a framing member or strap is found, the
apparatus searches right and left and up and down to determine the
availability of an area sufficiently large to print thereon and
which thereafter prints a label directly on the surface by means of
an ink applicator which label is located between the framing
members or straps around the carton. A multiple head apparatus is
incorporated to print on several sides of the carton.
Inventors: |
Ahlgren; Erick L. (Houston,
TX), McMorris; Arthur H. (Houston, TX), Schweppe; Joseph
L. (Houston, TX) |
Assignee: |
Houston Engineering Research
Corporation (Houston, TX)
|
Family
ID: |
23385663 |
Appl.
No.: |
05/352,570 |
Filed: |
April 19, 1973 |
Current U.S.
Class: |
101/35; 347/37;
347/4; 101/481; 101/484; 400/30 |
Current CPC
Class: |
B65B
61/26 (20130101); B41F 17/24 (20130101) |
Current International
Class: |
B41F
17/00 (20060101); B41F 17/24 (20060101); B65B
61/26 (20060101); B65B 61/00 (20060101); B41f
017/24 (); G01d 015/18 () |
Field of
Search: |
;346/75 ;101/35,41-44,1
;197/1R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Crowder; Clifford D.
Claims
We claim:
1. A label printing apparatus for printing a label directly on a
package, comprising:
probe means for finding the package on which a label is to be
placed;
said probe means being movable relative to such a package to find a
side thereof and including means forming a signal indicative of
finding a side of the package, and means contacting the package
during printing;
print head means including means for applying ink for forming
characters which comprise a portion of a label;
means for moving said print head means and said probe means in a
specified pattern relative to the side of the package to enable
said print head means to form the label on the package, said means
for moving further including means responsive to said means
contacting the package to control inward and outward movement of
said print head means with respect to the package during printing;
and
control means for providing print signals to said print head means
indicating the label to be printed and driving signals to said
means for moving to control movement of said print head means with
respect to the package.
2. The apparatus of claim 1 wherein said label printing apparatus
is adapted to be placed adjacent to a path of movement of a
succession of packages, and further including means for orienting
the packages relative to said apparatus to enable a side to be
presented to said apparatus whereupon said probe means is extended
toward the side and moves into contact therewith.
3. The apparatus of claim 1 wherein said probe means and said print
head means are moved by said motive means along the height and
width of the side of a package.
4. The apparatus of claim 1 wherein said mean for moving
includes:
a pair of generally parallel and separated rotatable lead
screws;
a travelling nut on each of said lead screws;
a supportive structure spanning between said travelling nuts and
moved therewith;
a lead screw incorporated in said supportive structure at right
angles to said pair of lead screws;
a travelling nut on said lead screw; and
means connecting said travelling nut to said probe means to convey
movement in two orthogonal directions to said probe means.
5. The apparatus of claim 4 wherein said means for moving includes
means for moving said probe means bi-directionally along a third
orthogonal direction.
6. The apparatus of claim 5 wherein said print head means includes
means for positioning said print head means within a specified
range of a package.
7. The apparatus of claim 1 wherein said moving means moves said
probe means and said print head means as a unit along a path toward
and away from the package, and further including a motor and
connected motor control circuit means which drives said probe means
and said print head means along the path.
8. The apparatus of claim 7 wherein said motor rotates a lead screw
which engages a travelling nut which is secured relative to said
probe means.
9. The apparatus of claim 7 including a pair of spaced guide means
adjacent to said probe means for mounting said probe means for
movement along the path.
10. The apparatus of claim 7 wherein said moving means includes a
support mounting said print head means to the rear of said probe
means.
11. The apparatus of claim 1 including
a generally upright support;
a carriage means movably mounted on said support;
second means for moving said carriage means vertically on said
support;
third means on said carriage movable to the right and left and
perpendicular to said second moving means;
said third means including a movable structure supporting said
movable means and said probe means for movement perpendicular to
the operation of said second means.
12. The apparatus of claim 11 wherein said second and third moving
means include stepping motors.
13. The apparatus of claim 11 wherein said second moving means
connects to a rotatable screw which advances said carriage
means.
14. The apparatus of claim 11 wherein said carriage means includes
a pair of parallel guide members, one of which is rotatable in
cooperation with said third moving means.
15. The apparatus of claim 1 further including an ink applicator in
said print head means which is supported above and to the rear of
said probe means.
16. A label printing apparatus for directly printing a label onto a
container, comprising:
a. printer means for forming the label by selectively applying ink
directly to the container under control of a series of print
signals;
b. print head means for moving said printer means in a sequence of
scanning movements with respect to the container so that the
printer may selectively apply ink to form the label on a surface of
the container; and
c. probe means for contacting the surface of the container being
printed and for sensing the position of said printer means with
respect to the container during printing;
d. control computer means comprising:
1. means for forming print signals, in accordance with the
information content of the label to be printed, to control ink
application by said printer means; and
2. means for providing driving signals to control movement of said
print head means in the sequence of scanning movements with respect
to the container wherein the label is directly printed onto the
container, and
e. means for controlling inward and outward movement of said print
head means with respect to the container in response to said probe
means to accommodate for small variations in the container
surface.
17. The apparatus of claim 16, wherein a succession of containers
are moved past said apparatus to receive labels with varying
information, and wherein said control computer means comprises:
means for forming print signals in accordance with the varying
information content of the labels to be printed.
18. The apparatus of claim 16, further including:
motor means for driving said print head means to thereby move said
printer means.
19. The apparatus of claim 18, wherein said means for providing
driving signals of said control means comprises:
motor drive circuit means for providing driving signals to said
motor means.
Description
BACKGROUND OF THE INVENTION
Many products from a variety of industrial, fiber and food plants
are manufactured in bulk and are packaged for shipment to
customers. Such packages take the form of bales with straps or
bands in the same fashion as cotton bales. Another form of
packaging often used includes a cardboard or thin wood container
which is reinforced on the exterior by a number of bracing members
of heavier stock. The straps, whether made of plastic or metal,
form an indentation which distorts the profile. The external
framing members protrude from the side and interrupt the smooth or
planar surface. The packaged products require labels which may
contain unique information regarding the package.
Heretofore, many labels have been made on detachable cloth or paper
gummed labels which are applied in some fashion to the surface.
Hand printing and attachment are costly and subject to error. If
they are placed over an external framing member or a strap, the
change in profile distorts the label and its attachment is less
certain.
With a view of placing labels directly on the surface of the crate,
carton, or bale the present apparatus is able to locate a generally
planar surface on the bale which is sufficiently large to receive
the label. The label is printed directly on the surface to avoid
the problem of transfer of adhesive labels and the like. The
apparatus is therefore capable of imprinting a label containing
information unique to a specific package, bale, carton or container
at a generally designated location on the item. It is further able
to position a printer head by movement in three orthogonal
directions under command of a digital control computer where basic
information about the package is supplied and imprinted.
One object of the present invention is to provide a sensing
mechanism which locates the package, bale, carton, container or the
like and positions the printer head at a beginning point selected
so that the label will be located on a generally smooth planar
surface.
Another object of the present invention is to provide a sensing
mechanism which locates steel bands which have been placed around a
package or bale so that printing on the steel bands can be avoided.
The ability to move in three dimensions enables the print head to
follow the print surface even though that surface is not perfectly
planar and is not exactly parallel with the plane of the printer
mechanism. In other words, the printer mechanism can follow the
surface whether it is planar, slightly contoured or not perfectly
aligned.
SUMMARY OF THE PRESENT INVENTION
The present invention includes a print head which is carried on an
XYZ system capable of movement along an orthogonal axes. It is
preferably adapted to be positioned adjacent to a conveyor or other
path where packages or cartons travel. The package or carton is
weighed or other information is provided as an input to a storage
device. The storage device is scanned by a digital control computer
which reads the input information such as weight, destination,
consignee and the like. The digital control computer formats the
information. It is formatted to fall within a surface area of a
specified range. The carton is curbed and the print head is
positioned above a probe which locates the sidewall of the carton.
The probe extends outwardly until the carton is engaged. It then
moves horizontally and vertically to find a generally smooth
portion of the facing surface on which the label can be imprinted.
It particularly locates external frame members or bands which
distort the planar surface. Once an area of sufficient size has
been located, the print head is positioned at a beginning point and
scans across the designated area printing directly onto the carton.
Thereafter, the probe which locates the surface and the print head
are withdrawn and the carton can move on. One embodiment discloses
two print head mechanisms which are arranged at 90.degree. to print
on different faces of a generally rectangular carton. Additional
print heads can be used.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing a dual head labeled printing
mechanism installed at right angles relative to a conveyor for
printing on two faces of a container or carton;
FIG. 2 is an elevation view of one print head which is mounted for
movement in orthogonal directions;
FIG. 3 is a view taken along the line 3 -- 3 of FIG. 2 showing a
plan view of print head carrier and associated apparatus;
FIG. 4 is a view taken along the line 4 -- 4 of FIG. 2 showing the
apparatus of FIG. 3 in side view;
FIG. 5 is a sectional view taken along the line 5 -- 5 of FIG. 3
and further including internal details of construction;
FIG. 6 is a side view, partly in section, of the print head
mechanism and apparatus which extends it toward a carton for
imprinting;
FIG. 7 is a bottom view of the apparatus shown in FIG. 6;
FIG. 8 shows a path of the print head on a typical bale; and
FIG. 9 is a schematic block diagram of the electronic apparatus
associated with the direct label printing apparatus; and,
FIG. 10 is a schematic of one motor and the drive circuit for its
operation .
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Attention is first directed to FIG. 1 of the drawings where the
present invention is indicated by the numeral 10. It is installed
adjacent to a conveyor 11. The conveyor 11 transfers a container or
carton 12. The carton 12 has external framing members 13 on it.
They interrupt the integrity of the generally planar sides and
prevent the application of a label at a random position on a side.
Rather, a clear space must be located by the present invention
which then works with the clear space left between the bands. The
clear space on which the label ought to be printed is indicated
generally by the numeral 14, it being understood that the face
where the printing actually will occur is facing the apparatus 10.
The significant point is that the area 14 is generally between the
frame members 13 which destroy the generally smooth profile.
The carton 12 may be formed with steel or plastic bands. They wrap
tightly around the cardboard or canvas covered bulk shipment and
hold the contents in. They function differently in that they
distort the profile in a manner differently from the framing member
shown but the net result is the same.
A third type of container includes those which are generally
rectangular, having no straps or framing members, leaving generally
planar sides which are usually perpendicular to another.
In FIG. 1, the numeral 15 identifies a print head assembly which is
duplicated at two locations which are preferably at right angles to
one another for printing on right angle faces of the container 12.
Only one may be required in many circumstances and to this end, one
of the two can be omitted. On the other hand, three or more print
heads may be included. Inasmuch as they are identical in
construction and operate in the same manner, it is believed that a
description of only print head assembly 15 will suffice.
The carton 12 travels the conveyor 11 and is curbed or cornered to
be brought into near proximity to the present invention. By way of
example, a single print head assembly can be positioned adjacent to
the side of a conveyor and a set of converging curbs can be used to
align the carton. In the arrangement shown in FIG. 1, it can be
cornered by the high edge plates adjacent to the conveyor system,
then imprinted and thereafter permitted to travel the remainder of
the conveyor system. In any case, it is only necessary that the
carton or container be brought in the near proximity and its
presence detected. For this purpose, a photocell 16 positioned at a
point above the container 12 responds to the interruption of light
from a light source below the container and below the conveyor to
indicate near proximity of the container. When the photocell 16
forms a signal, the labeling equipment 10 begins operation.
The print head assembly 15 is shown better in FIG. 2. The
surrounding structural housings has been omitted for sake of
clarity. In FIG. 2, a supportive framework 17 extends across the
bottom of the equipment and supports an upstanding pair of columns
18. The columns 18 are identical and to this end, a description of
one will suffice for the other. The two columns 18 each support
similar apparatus. The columns are, in fact, parallel to long
screws having a helix or thread extending their full length. Each
column 18 supports and aligns a travelling nut assembly at 19.
Again, the travelling nut assembly is duplicated at both sides of
the apparatus.
The travelling nut assembly 19 is guided by the support column 18.
The travelling nut has a span or length which is defined by an
external housing. The housing supports a pair of smooth, parallel
horizontal guide bars 20. The guide bars 20 span the horizontal
distance between the travelling nut assemblies 19. They are
preferably spaced apart. The guide bars or rods 20 support a
carriage generally indicated at 21 which will be described in
greater detail hereinafter. A lead screw 22 is parallel to the
guide bars 20 and positioned between them. The lead screw extends
to the right hand travelling nut assembly 19 as shown in FIG. 2 and
is operatively connected with a drive motor 23. The drive motor 23
is geared down by an appropriate gear box or belt and pulley
mechanism. It rotates the lead screw 22.
Attention is momentarily directed to FIG. 3 where the motor 23 is
shown to the side of the travelling nut assembly 19. It is
supported by an appropriate bracket 24. The guide rods 20 and the
lead screw 22 are arranged vertically one above the other.
Going now to FIG. 6, the numeral 25 identifies an upright frame
member of the carriage 21 which spans the three parallel members 20
and 22. It supports a travelling nut 27 which is engaged with
threads on the lead screw 22 so that rotation of the lead screw
moves the travelling carriage 21 to the right or left. Returning
now to FIG. 2 of the drawings, the operation of the equipment will
be described in so far as it relates to travel to the right and
left as viewed in FIG. 2 or movement along the X-axis. The carriage
21 is guided by the guide bars 20. The motor 23 through an
appropriate gear box rotates the shaft 22. The threaded shaft
engages the travelling nut 27 which is built into the carriage 21.
Rotation in one direction advances the carriage 21 to the right and
rotation in the opposite direction advances it to the left. The
range of movement is of course limited by the travelling nut
assembly 19 which is supported on the upright columns 18 as viewed
in FIG. 2. In other words, the carriage 21 can move to and fro
limited by the width of the apparatus.
The foregoing is directed to the mechanics of movement in the
X-direction. For movement in the X-direction, it will be observed
that a single lead screw and single travelling nut is used. Of
course, alignment of the equipment is maintained by the use of the
parallel guide rods 20. The vertical dimension in FIG. 2 will then
be defined as the Y-direction. Movement in the Y-direction is
guided by the columns 18. This advances all of the X-axis apparatus
as a unit. For a better understanding of operation of this
equipment, attention is momentarily directed to FIG. 5 of the
drawings. The numeral 30 identifies the Y-axis drive motor. It is
connected through appropriate gears at 31 and then to a drive shaft
32 which spans the apparatus. The drive shaft 32 at its left hand
end extends to a fixed housing 33. A bushing 34 supports the shaft
32 in the housing. A bevel gear 35 is placed on the shaft 32 and
engages a mating bevel gear 36. The bevel gear 36 is supported
adjacent to the shaft 32 and the other gear 35 by means of a
bushing 37 which bushing rests in a wall 38 of the housing 33. The
gear 36 is locked to an upright shaft 42 which of course is a lead
screw. The travelling nut assembly 19 includes a structural portion
39 which enables the travelling nut to be connected with the guide
bars 20 and a generally tubular housing 40 which contains the
travelling nut assembly itself.
On the right hand side of FIG. 5, similar apparatus is likewise
incorporated. It is arranged somewhat differently in that the bevel
gear is located on the left rather than on the right. However, the
remainder of the apparatus is the same in construction and
arrangement.
The structure of FIG. 5 enables the motor 30 to rotate the shaft 32
which then rotates the lead screws 42. The lead screws rotate in a
common hand or direction. The travelling nuts 19 supported on the
lead screws are not free to rotate but rather traverse the length
of the lead screws because of the structural interconnection
between the travelling nuts assemblies 19 as illustrated in FIG. 2.
Thus, motion in the Y direction is accomplished under the urging of
the motor 30.
The travelling nuts mentioned to this juncture are preferably ball
nut drive mechanisms manufactured and supplied by Thomson
Industries, Inc. The motors are preferably manufactured by the
Superior Manufacturing Company of Connecticut and sold under the
trademark "Slo-syn." The motors step 1.8.degree., or 200 steps per
revolution. The driving circuit is also supplied by the same
source.
Attention is directed to FIG. 4 of the drawings where the numeral
42 identifies the vertical lead screw which is spaced to the rear
of and parallel to the guide post 18. As shown in FIG. 4, the
travelling nut 40 is engaged with the lead screw 42. Rotation of
the screw 42 imparts upward or downward movement to the travelling
nut 40 and hence to the assembly 19 which is attached to it. The
same apparatus is duplicated on both sides of the equipment so that
the X-axis apparatus previously described moves upwardly and
downwardly in the Y-direction.
Attention is next directed to FIG. 6 and FIG. 7 which show the
print head carriage 21. As will be recalled, it has an upstanding
bracket 25 which engages the guide bars 20 and the horizontal lead
screw 22. This maintains the equipment generally horizontal without
regard to movement along the X or Y-axes. The apparatus shown in
FIG. 6 and 7 jointly includes a drive motor 45 connected to a gear
box 46 for driving a belt 47 which connects to a pulley 48 and
rotates a shaft 49. The shaft 49 is just above a fixed bottom plate
50 which is fixed to the upstanding bracket 25. The lead screw 49
engages a travelling nut 51 which travels forewardly and rearwardly
in the Z-direction upon rotation of the screw 49. As shown better
in FIG. 7, the numeral 50 identifies the fixed portion of the
bottom which does not move in the Z-direction. The fixed portion
includes a fixed cylinder 52 located along both edges. A slidable
rod 53 extends into and out of the cylinder 52. The cylinder 52
serves as a guide for the rod 53 which reciprocates. This is
duplicated at both sides of the apparatus. The rod 53 extends
outwardly to a bumper 54. The bumper 54 supports a mounting plate
55 on the top side. The mounting plate is adapted to receive an ink
printer 56. More will be noted concerning the printer
hereinafter.
Returning now to FIG. 7, the bumper 54 carries a projecting probe
59. The probe 59 is also movable along the Z-axis. It is spring
loaded by a spring 60 mounted around a shaft 61 for purposes of
guidance. A switch 62 responds to the force of the spring 60. The
switch forms signals which drive the motor 45. The switch 62 is off
when the spring force is in a specified range. When the force is
outside the range, the motor is driven to move the probe in a
direction to alter the spring force to the desired range. When the
force is in the specified range, the print head is in an operable
range of the surface on which it prints. When the range is
incorrect, the printing may be distorted.
The motor 45 advances the printer 56 along the Z-axis in the
following manner. The motor drives the shaft 49 which rotates
causing the travelling nut 51 to be advanced or retracted. Movement
of the travelling nut 51 is coupled to the mounting plate 55. The
plate 55 moves forwardly and backwardly guided by the rods 53 which
prevent canting of the plate 55. The apparatus advances until the
probe 59 touches the surface of the carton. The probe 59 is pushed
inwardly, compressing the spring. When the spring is compressed to
a specified force, a signal is formed by the switch 62. The signal
is supplied, interrupting operation of the motor 45. The switch 62
thus responds to pressure applied by the spring. It operates the
motor 45 when the probe 59 is not touching anything or when the
spring is excessively compressed. In other words, the spring 60
tolerates a range of variation in which the motor 45 is not
operated at all. However, pressure in the spring 60 which is too
small or too great initiates operation of the motor 45. From this
description, it will be understood how the apparatus has a range of
tolerance for slight variations in the surface on which the label
is to be printed.
The probe 59 thus senses the presence of the surface on which the
label is to be printed. It positions the printer 56 at a location
where the surface is neither too close or too far. The probe 59
thus responds to either the contour in the case of a wooden crate
or to the presence of steel bands, in the case of band wrapped
cartons to determine the location of the obstacles of printing. For
detection of steel bands, the probe preferably incorporates a
ferrous material sensitive head. The head forms a signal when a
steel band is encountered. In the detection of wooden framing
members about a crate as exemplified in FIG. 1, it forms an
indication of an encounter with an external framing member when it
is unable to traverse any further, indicating that it has abutted
against the edge of a framing member. In that instance, the profile
is indicated by a fairly abrupt change in surface, so abrupt that
the probe is unable to move over the change in surface. The surface
change may not be so extreme and will be detected in the instance
of a profile change where a plastic band is used by observing the
derivative of the motor driving signal.
Attention is next directed to FIG. 8 of the drawings which
illustrates the container or carton 12 and shows how a single
letter will be painted on the exterior. The carton or container 12
is preferably of wooden construction for purposes of this example,
although it should be understood that such carton may be formed
from numerous other known materials. A band, strap or external
frame member 13 is formed about carton 12 for structural
reinforcement. In the example, three framing members are included,
two being vertical and the third being horizontal and somewhat near
the bottom. Once the carton 12 is sensed in near proximity of the
equipment, the probe 59 is slewed to a programmed XY position.
Along the Z-axis, the carriage 21 is retracted. Once it is slewed
to a specified XY position which is indicated by the numeral 63a in
FIG. 8, it begins to search for the frame members 13 which
determine the writing field. For purposes of definition, the
numeral 63 identifies the writing field which must be spaced
between the frame members. The writing field must typically equal
or exceed a specified minimum. For instance, suppose that the
weight and destination are to be painted on the carton or container
12. This may require a specified surface area such as 4 inches in
vertical height and 10 inches horizontally. Of course, these
dimensions are specified and the apparatus then searches for an
area or writing field 63 which equals or exceeds these
dimensions.
The apparatus is programmed to a beginning point 61 which will be
assumed to be in the writing field, or between the frame members
13, and not to the side where it may be impossible to obtain
sufficient space to write on the crate 12. In any event, the
apparatus is slewed to the beginning point 63a. At this juncture, a
choice can be made whether the apparatus will search horizontally
vertically, or in combination. For simplicity sake, the numeral 64
identifies the route which the probe follows where a vertical
search is first begun. If there is only one horizontal framing
member, it is wise to locate it and to this end, the vertical
search is begun from the beginning point, and the probe moves
downwardly along the path 64. When it encounters the frame member
13, the probe then travels along the path 65 adjacent to the frame
member until a vertical frame member is encountered. It then
travels upwardly along the indicated path 66 until adequate
vertical clearance is measured. Again, this is a dimension which is
specified in the beginning. At this juncture, two sides have been
located. The remaining question is whether or not the horizontal
clearance is adequate. The apparatus then travels along the path 67
to measure the horizontal clearance. This too will then be tested
to determine if it is adequate. In some instances, it will not be
necessary to measure along the path 67 because it is known that the
vertical framing members are more than a sufficient distance apart
to enable the label to be placed on the carton. For instance, the
distance might exceed by three or four fold the maximum width of
the label. In that event, there is not need to seek out the right
hand framing member 13 because more than adequate clearance is
available. However, assuming the worst case, the path 67 shows the
route which the probe travels to find the right hand frame member.
Once it has been found, the distance of the path 67 is measured and
if adequate, the label can be printed.
The numeral 56 in FIG. 6 identifies the printer apparatus. It is
preferably a bought item manufactured by the A. B. Dick Company and
sold under the trademark "Videojet." It is an apparatus which has a
small orifice which sprays a procession of droplets of ink across a
charged plate and the droplets of ink form a character or
impression shaped by control circuits in the apparatus. The
apparatus is used in the following manner. The numeral 68
identifies a slight downward step and the apparatus then begins a
scanning mode or movement along the path or scan 69. The path 69 is
the first writing path. The Videojet equipment is operated in a
manner such that no ink is applied to the crate 12 except when a
character is to be printed. Characters, however, are not printed
individually, rather, an entire line of characters is scanned in
horizontal motions and ink is applied so that several scans will
write an entire line. The scan 69 is the first one where ink is
applied.
For purposes of explanation, the letter B is shown in FIG. 8. The
scan 69 moves along the top edge of the letter B and applies ink at
70 which is a portion of the top of the letter B and applies ink at
70 which is a portion of the top of the letter. The scan 69 moves
all the way to the left and the device then indexes downwardly
again along the path indicated at 71. The downward movements at 68
and 71 are of necessity fairly short. It then enables the equipment
to form a subsequent scan along the path indicated at 72. Again, no
ink is applied except when the equipment is so commanded and ink is
then applied to continue building up the character as illustrated
in FIG. 8. The scans which move horizontally alternate in
direction. There is no need to return the apparatus from the right
hand end of each scan to the left before beginning another
operation. In other words, the return trip itself is, in fact, a
scanning operation.
Horizontal scanning to and fro is continued proceeding from the top
of the labeled area 63a to the bottom. The print field 63a is then
imprinted with the appropriate label. When the last ink has been
applied, the equipment can be retracted. That is, the printer 56 is
retracted along the Z-axis to a withdrawn position.
During actual printing, the probe 59 is in contact with the
surface. It is able to accommodate small variations in profile.
This is accommodated at the spring 60. Moreover, the motor 45 can
be operated to slightly advance or retract the printer 56. This
will enable it to write over a rough surface. The probe will be
observed to be in contact with the print field 63a at a point
somewhat below the place where the ink is actually applied. It is
preferable to write from top to bottom so that ink previously
applied is not smeared by the probe. The vertical gradation in
print is subject to variation depending on how large the print is
to be. The coarseness or fineness thereof and other scale factors.
To this end, the incremental downward steps 68 and 71 are
preferably specified so that the fineness or degradation in the
print meets some standard.
Attention is next directed to FIG. 9 of the drawings which is
schematic block diagram of the electronics included with the
apparatus. It is generally indicated by the numeral 80. The numeral
81 identifies a digital control computer where information to be
printed is input from a source 82. This is subject to variation of
worldwide range. It may typically include weight and destination.
It is formatted and appropriate scale factors applied. The data
from the computer 81 is next supplied to a printing system
interface 85. This printing system interface equipment 85 is
equipment which is supplied with the Video Jet printing equipment
from the A. B. Dick firm. The data is supplied from the interface
85 to a printing system controller which forms print signals for
the printer 56. The signals are binary in form in that they control
the application of ink. In addition, the probe forms signals
indicating its contact with the carton or crate 12. These signals,
in conjunction with position sensors 92, indicate the whereabouts
of the printer 56 with respect to the XYZ-axes.
The position sensors are mechanically connected to the apparatus
shown in FIGS. 2 - 7 inclusive to indicate the whereabouts of the
printer 56. These signals are provided to a printer mechanism
interface 83. The digital control computer 81 provides signals to
the printer mechanism interface 83 which then delivers driving
signals to the XYZ-axis controllers 86, 87 and 88, inclusive. They
form motor drive signals for the motors 23, 30, and 45. These
signals are delivered to the print head assembly 15 previously
described. Of course, a signal is provided for each motor. The
print head assembly 15 includes limit switches. Limit switches are
provided on the travelling assembly 19 which limit movement in the
X-direction. These limit switches provide override signals to the
X-axis control 86. Continued operation of the controls 86, 87 and
88 is indicated to the printer mechanism interface 83. This enables
the printer mechanism interface to indicate to the computer 81 the
whereabouts of the printer 56 and the possiblity of encountering a
limit. It will be understood that two types of limits can be
encountered. One is a limit where the apparatus moves in the X, Y
or Z-direction to the limit of its capabilities. That is to say,
the motors 30, 23 or 45 have extended the equipment to the maximum.
A second type of limit is that indicates by the position sensors
92. This is a limit which arises from the shape or construction of
the package. This information is provided in the event of a
defectively constructed crate or container, one which has ruptured
or the like.
Attention is directed to FIG. 10 where a typical motor drive
circuit is shown. The preferred motor is the "slo-syn" previously
mentioned. The motor 23 is driven by a translator circuit 97 which
forms driving pulses applied on four wires to the motor which
causes it to step incrementally through a step of 1.8.degree.. The
translator is controlled in operation by a signal conditioning
circuit 98 which is supplied with the following inputs. One input
is a direction signal which controls direction of rotation. Another
input is the off-on input. A third input is an enable signal which
enables an oscillator in the translator to run. Only one output is
required and that is an end of step signal. Preferably, a pulse
indicates completion of a step. The pulse is returned to the
computer 81 (FIG. 9) to permit it to move on with the next step or
operation. When the next step is finished, still another pulse
indicates completion of the step and enables the next step.
The computer receives and scales the data to be formated. The
format must be converted to a scale which takes into account the
gear ratio and actual physical measure of each step. The computer
scans the data to be printed in its format and breaks it down into
print signals for the printing means. Printing control is a binary
function. As was discussed relative to FIG. 8, the formated data is
horizontally scanned and broken into a series of binary print
signals.
Several factors relating to use of the present invention ought to
be noted. The device is well able to print on curved surfaces.
While the drawings and description connote a planar surface, many
cardboard or wrapped cartons bulge and distort so that various
portions of the surface on which the label is printed may be
described as a curved surface. In like manner, the present
invention can be used to print on drums and the like provided the
included angle of the arc of the printed label is not so great that
distortion occurs. For instance, it can print a label on a barrel
or drum along the length of the drum if the label is only one or
two lines tall. Printing around the diameter is limited by
distortion at the extreme sides of the message where the included
angle is great. The limits on angle may vary. For example,
legibility is preserved where the included angle of the label is
only 20.degree. to 30.degree.. When the angle is about 50.degree.
or so, the distortion becomes noticable. When angles of this size
are encountered, the label should be reformatted to decrease its
total width, perhaps increasing label height, and thereby reducing
the included angle.
Printing speed can be enhanced by using two or more print heads
which print lines which are interlaced. The number can be increased
subject to increased cost, and the speed of printing will be
increased accordingly. When two or more print heads are used, they
are offset from one another. This does not create any problem in
operation inasmuch as the scanning of the formated data interlaces
the lines and the drying time of the ink is normally
immaterial.
While the foregoing is directed to the preferred embodiment, the
scope is determined by the claims appended hereto.
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