U.S. patent number 3,787,884 [Application Number 05/321,890] was granted by the patent office on 1974-01-22 for ink jet printer.
This patent grant is currently assigned to International Business Machines Corporation. Invention is credited to Frederick M. Demer.
United States Patent |
3,787,884 |
Demer |
January 22, 1974 |
INK JET PRINTER
Abstract
An ink jet printing system which writes on a record medium by
expelling droplets of liquid ink from the cavity of a jet head
which is reciprocated repetitively along the printing line. A
piezoelectric transducer is used to generate ink droplets on demand
under control of suitable storage and character generating
equipment. Characters are formed by generating dots in a 5 .times.
7 matrix as the head traverses back and forth. The record medium is
stationary during printing and is advanced one row space at the
completion of each horizontal row of dots and also one line space
at the completion of each row of characters.
Inventors: |
Demer; Frederick M. (Vestal,
NY) |
Assignee: |
International Business Machines
Corporation (Armonk, NY)
|
Family
ID: |
23252480 |
Appl.
No.: |
05/321,890 |
Filed: |
January 8, 1973 |
Current U.S.
Class: |
347/68; 346/139D;
400/583; 400/470; 347/37; 347/9; 400/328 |
Current CPC
Class: |
B41J
19/14 (20130101); B41J 2/15 (20130101) |
Current International
Class: |
B41J
2/145 (20060101); B41J 19/00 (20060101); B41J
2/15 (20060101); B41J 19/14 (20060101); G01d
015/18 (); B41j 003/04 (); G06k 015/02 () |
Field of
Search: |
;346/75,79,139D,140
;197/133R,1R |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Hartary; Joseph W.
Attorney, Agent or Firm: Gerald R. Gugger et al.
Claims
1. An ink jet printing system for writing on a record member by
expelling droplets of liquid ink which comprises:
an ink jet head comprising a body member having a cavity with a
nozzle portion at one end and a piezoelectric - metallic diaphragm
sealed at the opposite end;
means for supplying liquid ink to said cavity;
means for reciprocating said jet head back and forth across the
front of the writing surface of said record member;
storage and character generating circuit means responsive to input
data to be printed for pulsing said piezoelectric diaphragm whereby
droplets of ink are expelled from said nozzle to produce rows of
dots on the record member as the head reciprocates back and
forth;
counter circuit means for controlling the drive of said storage and
character generating circuit means;
transducer means controlled by the mechanical motion of the jet
head for producing synchronization pulses for controlling the drive
of said counter circuit means;
drive means for spacing said record member;
first means responsive to said counter circuit means for actuating
said drive means to space the record member at the completion of
each row of dots whereby characters are formed in a dot matrix;
and
second means responsive to said counter circuit means for actuating
said drive means to space the record member at the completion of
each row of
2. An ink jet printing system as in claim 1 wherein said liquid ink
is
3. An ink jet printing system as in claim 1 wherein said record
member may
4. An ink jet printing system for writing on a record member by
expelling droplets of liquid ink which comprises:
a rotatable helically grooved level winding screw having turn
around channels at each end, said winding screw extending across
the writing surface of the record member and in close proximity
thereto;
a carriage nut mounted on said winding screw and having a follower
riding in the helical grooves;
an ink jet head mounted on said carriage nut, said head comprising
a body member having a cavity with a nozzle portion at one end and
a piezoelectric - metallic diaphragm sealed at the opposite
end;
means for supplying liquid ink to said cavity;
means for rotating said winding screw whereby said jet head
traverses back and forth across the front of the writing surface of
said record member;
storage and character generating circuit means responsive to input
data to be printed for pulsing said piezolectric diaphragm whereby
droplets of ink are expelled from said nozzle to produce rows of
data on the record member as the head traverses back and forth;
counter circuit means for controlling the drive of said storage and
character generating circuit means;
transducer means controlled by the mechanical motion of the jet
head for producing synchronization pulses for controlling the drive
of said counter circuit means;
drive means for spacing said record member;
first means responsive to said counter circuit means for actuating
said drive means to space the record member at the completion of
each row of dots whereby characters are formed in a dot matrix;
and
second means responsive to said counter circuit means for actuating
said drive means to space the record member at the completion of
each row of
5. An ink jet printing system as in claim 4 wherein said transducer
means comprises a toothed wheel rotatable with said winding screw
and a magnetic
6. An ink jet printing system as in claim 4 wherein said drive
means comprises a one-way clutch and feed roll means adapted to
space either a
7. An ink jet printing system as in claim 4 wherein said liquid ink
supply means comprises a vertically adjustable ink container and
supply lines for feeding the liquid ink to the jet head by gravity
flow.
Description
BACKGROUND OF THE INVENTION
Fluid droplet printing has been known in the prior art as
exemplified by the system shown and described in U. S. Pat. No.
3,596,275 which issued on July 27, 1971. In systems of the type
described in this patent, a jet of writing fluid or ink is caused
to issue from a nozzle in the form of a succession of tiny
individual droplets which are directed toward the surface of a
record member. As the individual droplets are formed, they are
given an electrostatic charge which is a function of the
instantaneous value of an input signal which is to be recorded. The
charged droplets are caused to pass between a pair of electrostatic
deflection plates. A constant high voltage charge is applied to the
deflection plates to produce a constant high voltage electric field
between the two plates. As the charged droplets pass through the
electric field, they are deflected from their normal path by an
amount which is a function of the magnitude of the charge on each
of the droplets and in a direction which is a function of the
polarity of the charge on the individual droplets. Each droplet of
the ink or writing fluid has its own unique charge characteristic
for directing it to the desired print position on the record
member.
It can be understood that systems of the above patented type are
relatively complex, costly, and difficult to implement. And for
some applications, this type of printer system is neither desirable
nor required. In the present application to be described, it was
desired to provide a low cost and simple printer for the production
of a hard copy duplicate of a message selected from those displayed
on a CRT terminal.
SUMMARY OF THE INVENTION
In the present invention an asynchronous liquid jet printer system
is provided which writes on a record medium by expelling droplets
of liquid ink from the cavity of a jet head which is reciprocated
repetitively along the printing line by way of a carriage nut and
level winding screw means. Attached to the drive shaft of the level
winding screw is a timing gear from which a magnetic head derives
the basic synchronization pulses for the jet head electronic
driving circuits. Liquid ink is fed to the cavity by gravity flow
and the back of the cavity is closed with a sealed in piezoelectric
-- metallic diaphram sandwich. This piezoelectric transducer is of
the extensional type in which motion is generated by applying a
voltage to the piezoelectric crystal in a radial direction. The
application of pulses to the transducer from suitable storage and
character generating equipment results in the generation of ink
droplets on demand.
Characters are formed by generating dots on a 5 .times. 7 matrix, 5
horizontally and 7 vertically, as the head traverses back and forth
so that printing occurs in both directions. The record medium is
stationary during the actual printing of each row of dots and
during the turn around time of the jet head at the end of each row,
a paper advance solenoid is actuated. At the end of seven of these
paper "character-row" advance cycles, all of the selected
characters for one line have been printed and during an eighth
cycle a line space solenoid is actuated to advance the paper to the
desired position for the top row of dots of the next character
row.
In the present embodiment, printing occurs 40 characters wide which
occupy a space of 4 inches. The circuitry for driving the printer
is addressable by switches to print selected characters in each of
the 40 character positions. To test character sequences and format,
to demonstrate graphics, and to print selected text an IBM 1130
computer system is attachable to the printer electronics. The 1130
in this case controls print-out from punched cards through Fortran
using an 1132 write statement.
The present system provides a relatively inexpensive liquid jet
printer which is adapted to duplicate character generation borrowed
from an associated CRT terminal. It also has advantages over other
ink jet systems in that the liquid ink is not pressurized, no drop
deflection system is necessary, and no guttering of unused ink is
necessary.
It is, then, a primary object of the present invention to provide a
novel low cost asynchronous liquid jet printer.
A further object of the present invention is to provide a novel
liquid jet printer wherein the liquid ink is not pressurized and no
drop deflection system is necessary.
A still further object of the present invention is to provide a low
cost liquid jet printer which is adapted for the production of a
hard copy duplicate of a message selected from those displayed on a
CRT terminal.
The foregoing and other objects, features and advantages of the
invention will be apparent from the following more particular
description of a preferred embodiment of the invention as
illustrated in the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view showing the ink jet printer
constructed in accordance with the present invention.
FIG. 2 is a front elevation view of the machine of FIG. 1 and shows
the ink jet head and the level winding means.
FIG. 3 is a side elevation view of the right side of the machine of
FIG. 1 and shows the drive mechanism.
FIG. 4 is a side elevation view of the left side of the machine of
FIG. 1 and shows the paper advancing mechanism.
FIG. 5 is a diagram illustrating the method of character
generation.
FIG. 6 is a diagram illustrating the scan data time and the pulse
rate.
FIG. 7 is a schematic diagram of the ink jet.
FIG. 8 is a block diagram of the circuitry for controlling the
printer.
FIG. 9 is a perspective view showing the ink jet head and carriage
assembly .
DESCRIPTION OF PREFERRED EMBODIMENT
Referring to FIGS. 1 and 2, the printer apparatus of the present
invention comprises a base plate 10 to which is attached the
plexiglass side plates 11 and 12. At the back of the machine, there
is pivotally mounted a hopper 13 which may be used, if desired, to
hold a stack of fanfold forms which may be of paper or card stock.
In front of the hopper, there is rotatively mounted in slots cut in
the side plates a shaft 14 which carries a supply paper roll 15. In
front of the paper roll, a motor 16 is attached to the right side
plate so that there is clearance between the underside of the motor
and the machine base plate. Fastened to the baseplate underneath
the motor is a paper guide plate 17 which curves upward at the
front of the machine, as shown in FIG. 3. The paper guide plate
extends across the machine and directly behind the top portion of
it is a platen bar 18 which is fastened to the side plates of the
machine. Across the top of the platen is a slitting bar 19 which
has a groove 20 extending across the front of it so that, if
desired, a portion of the paper may be slit from the roll and
removed by running a knife, or the like, along the groove.
Referring to FIG. 2, at the front of the machine there is a pair of
roller bearings 21 which are rotatable on a shaft 22 fastened on a
pair of spring brackets 23. In the paper guide plate, a pair of
slots 24 are cut in alignment with the roller bearings and, as
shown in FIG. 4, on the other side of the guide plate there is a
shaft 25 journaled in the side plates. Fixed on this shaft is a
pair of feed rolls 26 which are in alignment with the slots and
which coact with the roller bearings to advance the paper. Fastened
to the inside of the paper guide plate are three spring fingers 27
which serve to hold the paper against the platen bar 18. To
initially feed the paper into printing position, the paper is
manually advanced along the inside of the paper guide plate 17
until it reaches the feed rolls 26 which are then operated to
advance the paper the rest of the way by manually turning the feed
roll shaft counterclockwise by way of the knurled knob 28 fastened
on the end of the shaft.
To automatically advance the paper when printing is being carried
out, the feed roll shaft 25 is connected to a roller-bearing sprag
clutch 29 which operates to rotate the shaft only in the
counterclockwise direction. A paper advance arm 30 is connected to
the feed roll shaft by way of the clutch and the other end of the
arm is connected to a pair of solenoids 31 and 32 mounted on a
support bracket 33. Electronic circuitry selectively pulses
solenoid 31 during character generation to advance the paper for
dot row scanning and solenoid 32 is selectively pulsed for line
spacing between character rows. The increment that these solenoids
raise the paper advance arm 30 is translated to paper motion by a
return spring 34 which returns the arm down against an adjustable
stop screw 35 to effect the counterclockwise rotation of the feed
roll shaft through the sprag clutch 29. In the present embodiment,
solenoid 31 produces a paper advance of 0.0167 inch and solenoid 32
an advance of 0.064 inch.
As shown in FIG. 4, plexiglass cover plates 36 and 37 are provided
and fastened on the top of plate 37 is a U-shaped wire member 38
over which the paper is fed so that the paper is kept away from the
motor to thereby prevent heating of the motor. It should be
understood that it is not necessary to use roll paper and that
individually inserted cut sheets can be used. For some
applications, the cut sheets may be preferred such as, for example,
when duplicating a message selected from a CRT display.
Referring to FIGS. 1, 2 and 9, the reciprocating ink jet head and
carriage assembly will now be described. Journaled in the side
plates at the front of the machine is a level winding screw 39. The
screw is driven by means of a gear 40 thereon which is connected by
a belt 41 to a gear 42 on the shaft 43 of the motor. The motor runs
at a synchronous speed of 1800 rpm moving the jet head 44
bidirectionally across the face of the paper by means of a carriage
nut 45 riding on the level winding screw. The level winding screw,
similar to that found in fisherman's reels, has turn around
channels at each end which transfer a pivot follower 46 riding in
the helical grooves to the alternate return groove of the screw.
The follower 46 is captured in the carriage nut 45 which carries
the jet head 44 by means of a bracket 47. The carriage nut is acted
upon by friction and torques induced by a flat spring 48 fastened
between the nut and the base of the machine and the nut is
prevented from turning by engagement of a sliding surface 49 on the
nut to a sliding surface 50 on top of the paper guide plate. A
microswitch 51 at the left end of the winding screw is actuated by
the carriage nut to start a count for printing, as will be later
described. As best seen in FIG. 3, attached to the drive shaft of
the level winding screw is a 60 tooth timing gear 52 from which a
permanent magnetic transducer (variable reluctance) 53 derives the
basic synchronization pulses for the jet head electronic driving
circuits.
Referring now to FIG. 7, there is shown the details of the jet head
44. Liquid ink is fed to the cavity 54 by gravity flow and is
introduced to the cavity by 2 curved pipe 55 at the top and the
drops are generated for printing on demand. The body 56 and nozzle
portion 57 are preferably of teflon due to the fact that teflon
resists wetting and thereby resists free bleeding of the jet. The
nozzle diameter would typically be in the order of 0.004 inch in
diameter.
The back of the cavity is closed with a sealed in piezoelectric -
metallic diaphragm sandwich. The disc 58 of this sandwich is
typically 3/16 inch in diameter and 0.008 inch in thickness.
Fastened central to this disc, by epoxy, is a piezoelectric ceramic
wafer 59 which is 5/8 inch in diameter and 0.008 inch in thickness.
This piezoelectric transducer is of the extensional type in which
motion in a radial direction is generated by applying a voltage to
the piezoelectric crystal. Application of a positive pulse produces
inward radial motion of the crystal which buckles the metallic
diaphragm inward, in the manner of an oil can diaphragm being
pushed inward, and liquid is expelled from the cavity. The
application of one pulse produces one droplet of liquid or ink. The
application of two pulses produces two droplets, etc. As shown in
FIG. 9, a metal slide plate 60 is provided on the end of the
bracket 47. This plate slides across the paper and prevents the end
or tip of the jet nozzle from contacting the paper.
Referring now to FIGS. 2 and 4, a supply of liquid ink is placed in
a container 61 mounted on a platform 62 which is vertically
adjustable by way of a slide plate 63 and screw 64 so that the
height of the container can be adjusted to control the gravity flow
of the ink. An air vent hole 65 in the cap of the container
prevents an air lock and assists the gravity flow. The ink flows
out of the container through a liquid line 66 and is directed to a
T-connector block 67 fastened at the front of the base plate. The
loop of flat spring 48 is actually split and the two ends are
overlapped and fastened between the block and the base to provide,
in effect, a pair of twin oscillating springs. From the connector
block 67, the ink is directed by way of two balanced liquid lines
68 and 69 upward to another T-connector block 70 which is supported
on a mounting plate 71 fastened to the carriage nut 45. The
oscillating springs 48 also serve to support these liquid lines, as
well as the electrical lines to the jet. From the connector block
70, the ink is directed through a liquid line 72 supported in a
bracket 73 mounted on the carriage nut and the ink is then directed
from line 72 through the curved pipe 55 and into the cavity 54 in
the jet head 44. The liquid lines 68, 69 and 72 are actually
connected to the connector block 70 by way of metering restrictor
connectors 74 which comprise little needle inserts. During printing
when the jet head assembly is reciprocating, the liquid lines 68
and 69 are also reciprocated and as the head direction reverses,
these lines will bend and act as pumps to cause liquid surges. The
purpose of the restrictor connectors is to iron out these surges so
that there will be no bleeding of liquid from the jet onto the
paper. Connected to the top of the T-connector block 70 is a bubble
chamber 75 having an air vent hole 76 on top. This chamber
functions to prevent the build-up of pressure in the connector
block 70 and thus prevent liquid surges. The chamber and restrictor
connectors serve as a simple pressure filter system.
The method of character generation is outlined in FIG. 5 with the
relative jet head and paper motions shown at the bottom of the
chart. Print dots 77 are generated starting at the left side of the
paper and as the head traverses to the right. All of the top dots
of selected characters are printed in this "character row" motion.
During the turn around time, the paper advance solenoid 31 is
actuated and the spring 34 completes the paper advance for a
scan-to-left jet dot generation cycle. All of the second row dots
of the selected characters are printed during this right to left
head motion. A similar turn around cycle set-up and paper advance
now takes place. At the end of seven of these paper "character row"
advance cycles, all of the selected characters for one line have
been printed. During an eighth cycle, the line space solenoid 32 is
actuated and the spring advances the paper one line space. The
first scan of the next line of selected characters starts when the
head begins advancing to the right. In each case, the paper advance
is at rest during the character jet printing function and printing
thus occurs in both directions. Typical dimensions of the
characters and dot spacing are shown in FIG. 5. In the present
embodiment, printing occurs 40 characters and the 40 characters
occupy a space of 4 inches on a paper width of 5 inches. Of course,
other dimensional formats could be used.
The 5 .times. 7 character matrix is used to produce a message 40
characters in line width and 6 lines in length with line density
being 6 lines per inch. Character width and spacing are such as to
give a character density of 10 characters to the inch. The level
winding screw 39 which actuates the jet head is designed with a
lead of one turn per revolution and, as has been described,
directly attached to the screw is the 60 tooth emitter or magnetic
impulse wheel 52 from which impulses are sensed by the magnetic
reluctance pick-up head 53. These impulses are basic to the control
of all of the electronics of the machine, as will be described.
Since there is a character density of 10 characters to the inch and
since the winding screw moves the jet head laterally one inch
during 60 impulses, it is seen that with the 5 .times. 7 dot matrix
a character space of one dot exists between characters in
horizontal or line direction spacing. The character and character
space increments are 0.1 inches. The vertical dot spacing is made
approximately 0.016 inches resulting in a between line spacing of
approximately 0.067 inches for a line spacing of 6 lines to the
inch. This is shown graphically in FIG. 5 where the characters
"ETO" are sketched by dot position. At the bottom of FIG. 5 there
is shown how 7 horizontal "raster" mechanical scans of a controlled
dot position ink emitter generate these characters. It will be
noted that the first scan is from left to right, the next scan from
right to left, etc. A scan data time and pulse rate for a 4 inch
write to the right, turn around, and write to the left cycle is
shown in FIG. 6. During R-1, R-2, R-3 and R-4, the top line of 10
characters are written as the head moves horizontally one inch per
turn.
Referring now to the block circuit diagram shown in FIG. 8, the
motor 16, operating at 1800 rpm, drives the level winding screw 39
and the timing emitter gear 52 which is a 60 tooth wheel with one
tooth removed at the "home" position. This wheel is adjusted at
assembly to have an axial position on the level winding screw such
that the missing emitter tooth is registered with the magnetic
reluctance pick up head 53 at the first level winding screw
crossover after left turn around. The jet head is also aligned at
assembly to have a common perpendicular axis to this first level
winding screw crossover after left turn around. The magnetic
impulses are sensed by the head 53 and the impulses are fed to a
magnetic emitter -- amplifier -- shaper 78. The missing pulse from
the missing home tooth on the emitter wheel is reinserted and
identified as a home pulse in this amplifier. The output from
amplifier 78 feeds a six stage ring counter 79 and this counter,
because of the 5 character dot positions plus the single dot
character - space, as shown in FIG. 5, gives one character pulse
output for each six emitter pulses received. The character pulses
from counter 79 feed an up-down binary counter 80 and the purpose
of this counter is to count the chosen number of characters per
page width, which in the present embodiment is 40. By means to be
described, the first dot of the first character will be printed at
the first scan left level winding screw crossover after left turn
around. The up-down counter 80, therefore, counts 40 character
positions as the first print scan to the right proceeds to
completion. At the 40 character count, one output of the up-down
counter goes down in voltage level along a line 81 which signals
the read only storage (ROS) enable line in a 5 .times. 7 matrix
character generator 82 resulting in stopping further scan one
character generation signals. The jet head is now carried into
mechanical turn around on the right turn around section of the
level winding screw. The signal on line 81 to the character
generator ROS stays down during the entire turn around time.
Meantime, the up-down counter 80 is counting the ten more words
generated by the 60 tooth emitter wheel in this one revolution turn
around. At the end of this additional ten character turn around
time, the signal on line 81 from the up-down counter 80 is brought
back up in signal level allowing the character generator 82 to
again operate, this time as scan 2 proceeds to the left.
During the operation just described, the up-down counter 80 was
also sending character pulses to a row counter 83. The output of
the row counter, in the scan from left to right, identified row 1
along an output line 84. The output on line 84 goes to a logic
block 85 which controls whether the identified scan will print dots
from the character generator 82 in a left to right going
progression or in a right to left going progression in conjunction
with the 5 signal lines, identified as line 86, which leave the
ring counter 79 and also enter the logic block 85 to identify the
five dot times and to selectively gate the stored character out of
the character generator 82 along 5 lines, identified as line 87, in
the selected left or right progression. As shown in FIG. 5, scan 1
is to be a left to right progression as are scans 3, 5 and 7.
Similarly, upon right turn around the count in row counter 83
becomes even and the dot output from the character matrix is in a
right to left progression during scans 2, 4 and 6. The three output
lines from the row counter 83 are also shown as inputs to the 5
.times. 7 character matrix generator 82. Also, a branch line 88
from the row counter output line 84 feeds a solenoid driver block
89 for raster or inter-character output spacing at each turn
around. The row counter output lines 84, 90 and 91 feed an AND
block 92 and upon the count of eight rows, one output from the AND
block signals a solenoid driver block 93 to effect a line space.
Because of the mechanical structure of the solenoids 31 and 32,
both solenoid drivers 89 and 93 are activated at 8 row count with
the raster solenoid 31 aiding the line space solenoid 32 in
initiating the large line spacing.
The output from controls printing logic block 85 is taken to a
transducer driver block 94 to pulse the ink jet print head 44. A
branch output line 95 from the AND block 92 is taken to the AND
section of a single shot 96 whose purpose is to clear the counters.
The clearance of counters occurs at the end of row count 8 and the
coincidence of a new print cycle, as follows:
The microswitch or left margin switch 51, located at the left end
of the winding screw and actuated by the jet head carriage nut, is
connected to the latch section of logic AND block 97 and is held
after make until the missing tooth "home-pulse-signal" is received
at the first level winding screw crossover after left turn around.
At this time, the output of logic block 97 enters the AND section
of single shot 96 in conjunction with the row 8 count signal,
described above, and all of the counters are reset to zero and a
new count cycle is initiated.
The foregoing has described how information is read from the
character generator 82 by the machine operation and associated
electronics controlled by the level winding screw pulse emitter
wheel.
To select the character positions of a 40 character line buffer 98
that will either load that position or deliver that position to the
5 .times. 7 character matrix 82, six lines of address, identified
by the line 99, are delivered from the up-down binary counter 80 to
common lines, identified as line 100, which connect the 40
character line buffer 98 with a laboratory automatic interface unit
101. The line buffer comprises six 4 .times. 4, 64 bit, read-write
random access memories for the 40 characters. The interface unit is
essentially a digital multiplexer for channeling out of a suitable
computer 102 such as, for example, an IBM 1130. The common lines
between the line buffer and the interface unit may be disconnected
if manual switch loading of the 40 character line buffer is
desired. In this case, the same character will be read out of its
respective buffer position to the character matrix 82 as each
buffer address is received along line 99 to the buffer. In this
way, line after line of the same characters stored in the buffer
may be printed. Also, by manually changing switches represented by
the block 103 feeding the buffer, new characters may be manually
entered into the buffer.
Loading of the 40 character line buffer by the computer occurs
under control of the interface unit 101. A line, not shown, leaves
the row counter 83 bringing a line count of eight along the line
104 into the interface unit. During the "8" time, the line buffer
may be loaded from the computer. Under this control, a new set of
40 characters may be loaded at each "8" time or, in other words, on
a line by line dynamic basis as long as data is being received from
the computer in 40 character line widths.
While the invention has been particularly shown and described with
reference to a preferred embodiment thereof, it will be understood
by those skilled in the art that various changes in form and
details may be made therein without departing from the spirit and
scope of the invention.
* * * * *