Note: Descriptions are shown in the official language in which they were submitted.
BACKGROUND OF THE INVENTION ~
The present invention relates to apparatus and methods . ::
~or the generation of patterns, and more specifically
concerns enhanced apparatus and methods ~or the expeditious
creation o~ patterns of high precision, optionally o~
several aspects and/or thicknesses (i.e. thick, non-planar
articles of complex-compound shapes), from a medium of
photographic film or wave-energy sensitive material, by a
combination of computer controlled mechanical and electrical
1 systems.
iSignage fabrication often makes use of masks or stencils
:i 45 prepared by ~anual or semi-automated means, a resource-
costly process for a single end product such as an etched
stone marker or unique sign. In the fabrication of thick-
film circuits, printed circuits and other patterned -::-
products, a high quality monochrome master pattern is
usually produced (on photographic film, plate or as a
printing screenj and then manipulated by various means in
order to transfer its pattern to a substrate previously
treated or coated with a pattern-receptive ma1:erial (said
material could variously be described as a fi:Lm, paint, ink,
~ -
1~2S912
resist, plastic resin or other, which is of a wave-energy
sensitive nature). Various automated means are available for
the production and subsequent use or transfer of such
images~
Photoplotters, whether of the classical type having a
shuttered light source modulated by Yarious lenses and
aperture sets, of the scanning laser type having raster
and/or vector scan modes, of the phototypesetter type, or,
of the movable image generator type moving in two axes such
as described in Canadian Pat. No. 1,236,927, can all serve
in the production of master images for the above described
- processes. However, each one of these photoplotter types has
problems or drawbacks, particularly where the number of
; 15 subsequent parts requiring a transferred image is very
small, where the image generation is to be performed onto
the substrate itself directly without transfer from a master
- image, or where the initial "master" image is intended to
; serve as the actual product (such as one-off sign~ and it is
required to have several colors, be of several types of
materials of various properties and/or have a greater
thickness than that of a nominal single film or coating
depth.
A classical photoplotter has a photohead which is
displaced in a plane, above a film, in X and Y axes by means
of high-precision electromechanical drivers which may or may
not be provided with error compsnsating devices. According
to numerical instructions corresponding to a description of
the desired image, appropriate settings of the shutter and
apertures in the photohead, in concert with the X and Y axes
displacements, combine to expose the film with a pattern of
the image. This type of master image creation has several
proble~s, including the restricted number of apertures (and
thus image details or types) which can be used by the
photohead as a set, the slow speed of exposure, and the
opportunity for cumulative or other displacement errors
which may arise due to the repeated and combined movements
in X and Y axes of the photohead. Due to its slowness, such
a machine is unsuitable for the exposure of images directly
onto treated substrates in a production-line context and, by
the same token, is economically handicapped in an
applic~tion requiring the preparation of a master image for
transfer to a very small number of substrates or where the
actual image itself is the end-product desired (such as a
sign). Further, such machines do not have the capacity to
create other than a monochrome image of a single material
type and/or thickness, and are impractical for the creation
of large sur~ace area images.
Phototypesetters, although excellent tools for the
production of high quality text images along a given printed
line, do not lend themselves ~o the creation of non-linear
random images, especially over medium to-large surface
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areas! whether for master image preparation or production-
line lmaging.
Recently, scanning laser photoplotters have become
available. By using a laser beam reflected and directed by a
galvanometer driven mirror, a complex image can be recorded
upon a wave-energy sensitive film or coated substrate. T~le
scanning scheme can be of a raster or vector scan nature,
according to the machine's design. Both modes are limited in
precision and accuracy primarily by the level of resolution
attainable by the galvanometer scAn heads, whose lineariky
and repeatability are presently of the order of +.5% and
+.01%, respectively. Such instructions also require special
processing in order to correct for pincushion and tangent
distortions, inherent to such scan heads. Scanning over
large areas can also be a problem, as th~ maximum deflection
or scan angle is of the order of 20, requiring a scan head
mounting height approximately equal to the greatest X or Y
axis value to be plotted; dynamic refocusing of the laser
beam over such large areas is also problematical, both in
the preparation of instructions for each instantaneous X-Y
location as well as in the synchronized operation of the
linear translator-mounted dynamic focusing lens. Although
fairly rapid in operation, such machines do not have the
capacity to create other than a monochrome image of a single
material type and/or thickness; as stated above they are
also i~practical for the creation of large surface area
images.
More recently another type of imaging machine, described
in U.S. Pat. No. 4,~75,330, has been used for creating three
dimensional objects. In a preferred embodiment, a layer of
electromagnetic wave sensitive liquid is cured in the shape
of a pattern by means of a single source of focused light
tor other single curing cause, such as an electron beam or a
sprayed chemical) which is displaced in two axes of a plane
adjacent to the liquid, much as a photohead is displaced
above a photographic film. As such, the speed of pattern
creation by this machine is no greater than in any other
case where separate X and Y mechanical drivers are used to
displace a light source or photohead; patterns created over
large areas are thus prepared relatively slowly, a
significant problem in a production-line environment. Thick
objects are created by mechanically driving the cured layer
away from the exposure surface of the liquid's container and
repeating the curing process on the new layer of uncured
liquid. Other means of creating patterns which are
specifically described include the use of a fiberoptic
faceplate covered cathode ray tube ~a pattern generating
method similar to that of the movable image generator
described in Canadian Pat. No. 1,236,927), and the use of
one or many physical masks between a columnated, broad
ultraviolet light source and the liquid, thus curing the un-
m sked areas. This last imaging method is the source of
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5 132~l2
several problems, as a different mask must be created for
each layer having a different pattern, and the masks must ~e
installed and removed at the proper time and in the proper
order. Due to these problems, such a machine i~ unsuitable
for the exposure of images directly onto treated substrates
in a production-line context, and is economically
handicapped in an application requiring the preparation of a
master image for transfer to a very small number of
substrates or where the actual image itself is the end-
product desired (such as a sign of a thick or textured
nature). Further, such machines do not have the capacity to
create images or objects of more than one type of material
(i.e. each layer is of the same color and composition), and
are impractical for the creation of large surface area
images or objects having large X and Y values~ since as the
physical size of the cured object increases so must the bulk
and level of complexity of the cured layer driving
mech~nism, a situation which can lead to problem~ in the
- minimization of static and dynamic deflections and ensuing
distortions in the cured object.
However, there continues to exist a need for an automated
means of rapidly and precisely creating multicolored,
multicomponent thin images or patterns upon coated
substrates, as well as there continues to exist a need for
an automated means of rapidly and precisely creating
multicolored, multicomponent thick patterns of arbitrary
height.
i 30 Accordingly, it is an object of the present invention to
provide such a means, through the implementation of a method
and apparatus which avoids or minimizes the above de~cribed
complicated means of light source displacement and alignment
methods in two axes, of light ~ource focusing, of physical
mask placement, of the displacement of succe~siYe object
layers away from a li~uid surface and focussed light source,
as well as of other problems associated with the existing
art.
SUMMARY OF THE INVENTION
In general terms, the present invention provides a new
and improved sy~tem for creating a pattern or image upon a
photographic film or other wave-energy sensitive media, and
permits the creation of several, varying patterns or images
upon a corresponding number of thicknesses of wave-energy
sensitive media, each thickness being of the same or
differing color and/or composition.
In transposing the general principles of the present
invention into a preferred embodiment thereof, which is
presented by way of example and not by way of limitation, an
energy beam generator, which may be a non-columnated source
of ultraviolet and/or near-ultraviolet light, shuttered by
;
132~912
an array of transvective liquid crystal cells (or an
equivalent linear source of discretely addressable energy
beams), is displaced in a continuous fashion along a single
axis in a plane adjacent to an energy sensitive medium upon
which a pattern or image is to be exposed. Accordinq to the
instantaneous and absolute linear displacement of the energy
beam generator, the appropriate liquid crystal cells are
instructed to be transmittive or non-transmittive, causing
those areas below the transmittive cells to be exposed, thus
forming an instantaneous incrament, cross-wise to
displacement, of the overall pattern or image. Instantaneous
electromechanical displacement error is minimized or
eliminated by causing the liquid crystal cells to be
transmittive or non-transmittive as a function of
displacement measurements which are independent of the
nominal displacement commands or instructions received by
the displacement driver. Non-instantaneous errors due to
such sources as driver backlash are also redressed, by such
means as operating the drive system for a short distance
before the nominal initial exposure area is reached.
In the case where a single photographic film or thickness
of wave-energy sensitive media is to be exposed, a single
one-direction passage of the energy beam generator suffices
- 25 to transfer the entire desired single image or pattern to
the film or media. In the case where several, varying
; patterns or images are to be exposed upon a corresponding
number of thicknesses of wave-energy sensitive media, each
thickness being of the same or dif~ering color and/or
composition, a method of introducing such thicknesses is
required. The preferred embodiment of a method of
introducing such thicknesses to the exposure plane, which
may be the top surface of a portion of the machine, of a
non-wave-energy sensitive film or plate, or of a previously
exposed thickness of wave-energy sensitive media, is by
means of a non-aerosol atomized application or flooding of
the plane, with the use of fluid wave-energy sensitive media
such as paint, ink, resist, plastic resin, fluidized powder
or other material.
BRIEF ~ESCRIPTION OF THE DRAWINGS
Figure 1 is a perspective drawing of a presently
preferred apparatus incorporating the present invention's
principles of operation: it is in the form of a three-
quarter view in which, for the purposes of clarity, a
section and c~rtain components such as the control system,
cables, material transfer tubes and others are excluded.
Figure 2 is a top view illustrating an example of several
different pattarn features intended for exposure onto a
wave-energy sensitive media in order to create a film image,
or into a wave-energy sensitive fluid in order to create a
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7 13259~2
cured pattern, for use in the production of circuits,
signage, thick patterns, articles and other products, or as
an intermediate step to other ends.
~igure 3 is a top view, pictorial representation of a Y
axis exposure at a given X axis location: feature outline
points are obtained from information in the pattern from
Figure 2.
Figure 4 illustrates in top view the staggered placement
of several discrete arrays (of transvective liquid crystal
cells, light emitting diodes or other equivalent linear
imaging arrays) in order to form a compound array.
Figure 5 depicts in an end view the embodiment of a~
optical method of nullifying the offset effects of the
staggered arrays illustrated in Figure 4.
Figure 6 depicts in perspective a pictorial
representation of the embodiment of an alternative linear
wave-energy beam imaging device, such as a light emitting
diode array, affixed upon an exposure slide.
Figure 7 depicts in perspective an embodiment of an
exposure slide suitably equipped for the deposition and cure
of a flowable solid pha~e material.
Figure 8 illustrates the major links between the
presently preferred embodiment of the invention's expo~ure
apparatus and its control system.
DETAILED DESCRIPTION
In transposing the general principles of the present
invention into a preferred embodiment thereof, which is
presented heréin for the purposes of exposition, an energy
beam generator, in the form of a liquid crystal cell
shuttered source of ultraviolet and near ultraviolet light
is displaced in a continuous fashion over a photosensitive
film or a thickness of wave-energy sensitive fluid media
(liquid or solid3 in order to impa~t an image or pattern to
the film or to create an image or pattern of cured material
in the fluid media. A pattern or image of any density or
complexity can be created, by appropriately ordering the
liquid crystal cells to become transmittive or non-
transmittive at any given absolu~e displacement or
coordinate location. Appropriate information for the
preparation of automated actuating instructions for the
liquid crystal cells can be o~tained directly from a pixel
survey of a computer graphic representation of the pattern
or image in question, or, alternatively, I`rom a translation
of an existin~ geometric description of the said pattern.
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8 132~91 ~
The liquid crystal cell array permits the exposure of the
entire width of the film or media underneath it and, since
this array is placed perpendicular to the single axis of
displacement, the stepless process of exposure can be
performed very quickly and with the correction of any
displacement errors, as measured by a separate absolute
displacement sensor, in a continuous fashion by controlling
the transmittive/non-transmittive state of each liquid
crystal cell as a function of the previously prepared
pattern instructions and the instantaneously sensad absolute
displacement.
The maximum value of displacement speed is effectively
limited, in order of growing importance, by the sensing
delay of the absolute displacement sensors, the
transmittive/non-transmittive operation of the liquid
crystal cells, the transmittive/non-transmittive command
processing time, the exposure or curing speed of the target
media, the intensity of the wave-energy source, the
displacement acceleration/velocity values of the single axis
drive, and, in the case of the introduction of more than one
color or composition of thickness for a fluid media target,
the time of application of the said fluid media and the
refocussing of the shuttered light source. As compared to
other image creating systems displacement errors are
- minimized by li~iting physical movement of the energy source
to a single axis and maintaining its displacement at a
constant rate rather than requiring it to repeatedly start
and stop.
The presently preferred apparatus for the application of
the present invention's principles of operation is
illustrated in Figure 1 (for the purposes of clarity,
certain components such as the control system, cables,
material transfer tubes and others are excluded in this and
other figures, although it is understood that the required
numbers and types of such links are related to the described
equipment a6 depicted in each figure: Figure 8 illustrates
the basic relations and virtual links). A stiff space frame
10 forms the structural base and support of the machine.
Exposure ~essel 11 has a flat bottom surface 12 into which
are formed several rows of apertures (not shown) open upon a
chamber (not shown) evacuated by vacuum pump 14, thus
providing a means of supporting and temporarily immobilizing
the photographic film, plate or other substrate upon which a
single or a series of images or patterns, such as a circuit
pattern or an advertising image, is to be exposed. According
to the absolute dimensions of the apparatus or of the
intended end-product, one of vessel ll's walls may be
gasketed and hinged in order to facilitate the removal of
the said product (hinged wall is not shown). Mounted at an
upper edge of vessel ll is a solenoid valve 40 linked by
means of a length of high pressure tubing (not shown) to a
reservoir of non-reactive gas (not shown), said valve 40
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9 132a~12
allowing the introduction of said non-reactive gas into said
vessel 11 by means of low-pressure tubing 41. Edgewise fluid
draining depressions 15a and 15b (15b hidden from view by
the wall of vessel 11 with the section) are formed adjacent
to surface 12's longest edges (X axis). Formed at the bottom
of each depression lsa and 15b are several apertures (not
shown), said apertures utilized as the sources and sinks of
curable fluids of various colors and compositions when it is
desired to create patterns or images of varying color and/or
composition. Said curable fluids are stored in remote
reservoirs (not shown) and trans~erred from said reservoirs
to said apertures by means of bi-directional pumps (not
shown) and associated tubing (not shown). Linear bearing
guideways 17a and 17b are fixed upon the longer (X axis) top
1~ surface edges of frame 10, aligned in such a way as to be
coplanar to each other, within certain error limits, in a
plane parallel to and above surface 12. Linear bearing
blocks 18a and 18b rest upon guideways 17a and 17b and have
a single degree of freedom in the X axis.
Resting upon and affixed to bearing blorks 18a and 18b is
a gantry 19 which has Z axis linear bushings (not shown) and
transfer shaft pairs 20a and 20b passing through it. Slide
21, affixed to the lower extremities of shaft pairs 20a and
20b, is dri~en in either direction along the Z axis by servo
actuator 22, and monitored by a magnetic Z axis displacement
transducer composed of a linear scale 28 affixed upon a
surface formed upon one of the rods of transfer shaft pair
20b, extending along the full Z axis travel len~th, and a
position sensor readerhead 29 mounted upon-gantry 19. A
height level gage 38 for monitoring Z axis height of fluid
exposure media lies within the confines of vessel 11 at an
appropriate location affixed to frame 10. Gantry 19 and the
attached slide 21 are displaced in either direction along
the X axis by a metal positioning ~elt 23, which is driven
by servo motor 24 and supported by pulleys 25a and 25b.
Gantry l9's position is monitored by a magnetic X axis
displacement transducer composed of a linear scale 30
affixed to the frame 10, adjacent to guideway 17a and
extending along the full X axis travel length, and a
position sensor readerhead 31 mounted upon bearing block
18b. Belt bracket 26 transfers X axis translation forces
from belt 23 to gantry 19 along a line equidistant to
guideways 17a and 17b while allowing the placement of Z axis
actuator 22 along a coincident line by maintaining
sufficient belt slack between its two belt fixation points.
Affixed upon slide 21 is a wave-energy generator, whose
presently preferred embodiment is a non-columnated source of
- 5~ light emitting ultraviolet and/or near-ultraviolet
wavelengths, shuttered by an array of transvective li~uid
crystal cells 33. Light shield housing 34 surrounds and
encapsulates the said light source, preventing light output
from any direction other than through one or through several
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132~912
transmittive state liquid crys~al cell(s) of array 33.
Housing 34 also serves as a conduit for the supply and
exhaustion through hoses (not shown) of a cooling media such
as air propulsed by a fan (not shown). As re~uired in order
to satisfy a wide range of Y axis width constraints, two or
more discrete light sources and a corresponding number of
discrete arrays of transvective liquid crystal cells may be
combined to form a continuous wave-energy generator of
compound design. The transvective liquid crystal cells of a
single unit of the presently preferred array are aligned in
a linear row having a density of the order of 100 cells per
centimetre, each cell equipped with a focussing lens. The
vertical Z axis mobility of slide 2~ permits the focussed
light exiting from any transmittive state liquid crystal
cell's lens to impinge upon the exposure surface at an
optically correct distance according to: the thickness of
the photographic film or plate to be exposed, the number of
thicknesses of curable fluids of various colors and/or
compositions to be cured, or the 2 axis height variations of
a wave-energy sensitive material lying upon or bonded to a
substrate exhibiting curvature along the X axis (such as a
windshield or other piece of curved glazing from a road
vehicle).
In the case of an exposure surface having no significant
variations in height in the Z axis over the total travel
length along the X axis, such as a flat photogra~hic plate
or an even thickness of fluid, the appropriate Z axis height
of slide 21 is set to a desired value prior to scanning
according to either a known value for media thickness or
data obtained from gage 38. Slide 21 is thus driven by
actuator 22 until its physical position, according to Z axis
position feedback from readerhead 29, corresponds to the
desired one. The Z axis height setting is maintained as
gantry 19 and slide 21 are driven in the X axis by belt 23
over the full scanning travel length required. As slide 21
is displaced in the X axis, exposure of the media takes
place over the full Y axis scanning width simultaneously.
High precision imaging is obtained as the Y axis exposure
instructions sent to array 33 are synchronized with and
depend upon the actual physical X axis location of the array
and slide as determined with feed~ack from readerhead 31.
Positioning errors due to backlash, driver slippage, tharmal
expansion and other sources are thus minimized, while severe
misalignment of individual crystal cells in an array can be
compensated for by an anticipated or retarded cell state
instruction set specific to each cell.
Figure 2 is an illustration of an example of a pattern 50
intended for exposure onto a wave-energy sensitlve media, in
order to create a film image or a pattern of cured fluid.
Pattern 50 is made up of several pictorial features,
including a thick curved line 51, three adjacent rectangles
52, 53 and 54, the written word "FLOWER" 55, the Japanese
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11 132~gl2
Hiragana characters 56 meaning flower, and a figurative line
drawing o~ a flower 57. This pattern's features lie within a
coordinate grid having X and Y axes. According to the
principles of the present invention, pattern 50 represents a
set of points; each point is defined as the intersection of
two lines, one parallel to the X axis of a width
corresponding to the inverse of array 33's lineal density
and the other line parallel to the Y axis of a width
corresponding to the smallest unit of linear displacement
capable of being detected by X axis readerhead 31. In the
presently preferred embodiment of the invention, each of
these points has X and Y dimensions of the order sf .05 mm
by .~ mm. Each feature in pattern 50 is represen~ed as a
subset of such points, some of which contrast with th~ir
surroundings and thus form line segments to create feature
outlines or filled areas: these may be referred to as
outline points. As the physical scale of the pattern to be
exposed increases, from an area o~ a few square centimetres
to one of several square metres, the actual number of points
required to describe the pattern as well as the effective
attainable resolution of the pattern also increases.
Within pattern 50, each feature outline point falling
along the virtual line 58 corresponds to the physical
placement of a cell in array 33, within certain small error
limits (virtual line 58 is of width .05 m~, is parallel to
the Y axis and intersects the X axis at X=4). A source of
light shuttered by a device such as array 33 can expose an
equivalent image of the feature outline points along line 58
by instructing the liquid crystal cells corresponding to the
said points to be transmittive, while the remaining cells
corresponding to the background are instructed to maintain a
non-transmittive state. Figure 3 is a pictorial
representation of such an exposure, the result of which is
an image 60 consisting of two discrete feature outline
points 62 and 63, as well as a set of adjacent feature
outline points 61. Points 62 and 63 of Figure 3 correspond
to the feature outline points in Figure 2 of the
intersection between rectangle 54 and virtual line 58. In
the same manner, the set of adjacent points 61 of Figure 3
correspond to the feature outline points in Fiqure 2 of the
intersection between the filled ~eature 51 and virtual line
58. Similar contiguous line exposures of feature outline
points from X=0 to X=6 in increments of X=.05 mm would
~5 result in an image corresponding to the original pattern 50
of Figure 2. By this means, the presently preferred
apparatus is capable of rapidly exposing large numbers of
contiguous image line segments of essentially any dimension,
as t~e speed of line exposure is not related to line length
in the Y axis and is stapless in displacement along the X
axis.
From descriptive data, the preparation of instructions
for the crsation of any pattern or image can he the rPsult
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12 1325912
of various procedures, while the actual type or format of
such instructions can take many shapes. For the embodiment
presently preferred, the use of an initial source of raster-
like data is the most practical means of preparing
instructions for the control of discretely-operated
transvective liquid crystal cells. Although such data can be
obtained from manual means, complex patterns having an area
greater than a few square centimetres would render such a
task extremely time-consuming. An expeditious way of
lQ obtaining this data is to design the pattern with the
assistance of a computer graphics system, a function of
which is to create a numeric file containing a vector or
raster format description of the pattern. The numeric file
is thence translated by an appropriate computer program into
a set of successive linear outline point records, each
record containing the location in X and Y axis values of the
outline points falling along tne line X = Xprevio~ + ~X
specific to that record, as shown in the example above. The
new file containing these records has a format similar to a
look-up table, a table of instructions specifying which
array cells must be transmittive at any givsn X displacement
value in order to create a line image upon a wave-energy
sensitive medium. In the case where there exist Z axis
height variations in the target surface, the records in the
above file hold an appended field for Z axis height: a solid
modelling computer graphic system is useful in generating
the original data for such pattern records. In the case
where more than one thickness of liquid curing media is
required, whether of the same or differing color and type of
material, the records of the above file hold appended fields
for color and material type, respectively. In Figure 2 the
three rectangles 52, 53 and 54 of pattern 50 can thus be
cured from one or a multiple of thicknesses of fluid media,
such media being of the same or differing color and type of
wave-energy sensitive material, according to the
instructions contained in one or more record files; in the
same manner, each of the petals of flower 57 can be made to
be a different color and to exhibit a different acuity of
curvature in the XZ plane, according to the number of
thicknesses of media and the pres~ribed configuration of
each thickness. Existing patterns described in other types
of formats, such as the so-calle~ Gerber format used in
conjunction with traditional photoplotters, or plotting
instructions such as the so-called HPGL format, can all be
translated by simple software routines into a format
applicable to the presently preferred embodiment.
In reference to such a record file, the presently
preferred embodiment exposes an image by following certain
procedures. A control system, consisting of a small
conventional computer, possesses sufficient storage to
contain the entire set of pattern record files required to
describe a given pattern of an indeterminate number of
thicknesses, each of which may be of various colors and/or
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13 132~912
material types. The control system can be made to operate
various types of software, including a purpose written
program capable of calculating from pattern re~ord file
input data all of the commands required for the control of
the above described preferred embodiment. Upon its
activation the program initially verifies the status of
several of the machine's component parts, such as the X axis
position of gantry 19, the Z axis position of slide 21, the
Z axis height of any fluid which may be present in exposure
vessel 11, as well as the status of any other component
whose condition may change in the course of a pattern
exposure. After initial machine condition criteria have been
reviewed, the program prompts the user for the name of the
pattern record file to be used in the present exposure
session. If the appropriate file has not been previously
entered into the computer's storage memory, the program then
req~ests the user for a direct input of it. After having
obtained the correct file the program examines it to
determine the type of exposure media required as well as the
physical dimensions of the finished pattern, in X,Y and Z
axis, in order to inform the user whether or not the machine
is capable of creating the desired pattern image. Following
this general systems check the program informs the user of
the machine's condition and requests permission to undertake
certain corrective actions, such as driving gantry 19 and
slide 21 to their absolute zero positions, or,
alternatively, requests that the user perform an adjustment,
such as topping-off one or more reservoirs of wave-energy
curing fluid, as required; the program may also call for the
; 30 placement of such fluidized media having a certain chemical
composition or color in specifically numbered reservoirs.
According to pattern record file information, the program
then requests the placement upon surface 12 of a planar
media of a film which may or may not be wave-energy
sensitive. Subsequent to confirmation by the user that such
a placsment has taken place the planar media is immobilized
through the actuation of pump 14 and, if a liquid wave-
energy curing media is specified by the pattern record file,
the program orders the liquid corresponding to the first
record to be pumped onto the substrate, in an appropriate
amount. By actuating solenoid valve 40 the program may also
cause a non-reactive gas to be introduced into vessel 11, in
order to displace atmospheric oxygen which may inhibit the
cure of certain media. The actual exposure sequence can now
commence.
Initially, at the absolute zero point on the X axis, all
of the transvective liquid crystal cells of array 33 are in
a non-transmittive state; thus, no exposure occurs~ The
program causes a relay to activate the source of light
shielded by housing 34, and then calls upon an exposure
control routine to commence the review of the linear outline
point records of the file concerned. The first record is
read: the Y axis location of each indiYidual outline point
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~32~9~2
14
to be exposed at the first appropriate X axis position is
translated into a set of signals stored in an electronic
device (such as an array of latches). The routine then
issues a command to drive gantry 19 at a speed consistent
with the intensity of the said source of light within
housing 34, as well as with the sensitivity of the exposure
media. When the first appropriate X axis position is reached
(which may be at X = 0, according to the given pattern) the
latches, each of which is linked to a single liquid crystal
cell of array 33, simultaneously transfer their stored
signal to their respective cells. According to the signal
received, the cell may revert from a non-transmittive state
to a transmittive one, or, maintain a non-transmittive
state. Those areas of the wave-energy sensitive material
impinged upon by light passing through the transmittive
state cells are exposed or cured. As the signal transfer
occurs, and before sufficient time has elapsed to allow
gantry 19 to travel to the X axis position corresponding to
the second record as measured by readerhead 31, i.e. at X =
Xpre~io~ + X, the routine reads the second record and causes
a new set of signals to be transferred to the latches. Upon
reaching the second X axis record point the latches again
simultaneously transfer their signals to their respective
cells. According to the nature of the signal, and the
required exposure outline at that displacement value along
the X axis, each individual liquid crystal cell of array 33
may indep~ndently exhibit a state which is transmittive or
non-transmittive. As gantry 19 continues its stepless
displacement along the X axis the routine reiterates the
process of setting cell state transmittivity according to
the contents of each record corresponding to the
instantaneous increment of X axis displacement. When the
last record is read the routine issues commands to cause
belt 23 to stop driving gantry 19 and to induce a non-
transmittive state in all of the cells of array 33, at whichpoint control of the machine reverts back to the main
program. The exposed film or patterned substrate may now be
removed.
In the case of a pattern created in a liquid wave-energy
curing media, the program determines whether more than one
thickness is specified in the pattern's record file. If an
additional thickness of the same material is required, a
speciîic volume of the liquid is caused to bs pumped from
the original reservoir into exposure vessel 11, the level of
which is continuously measured by height level gage 38.
~epending on the magnitude in height change of the liquid
media's exposure surface, as measured by gage 3$, the
program may cause slide 21 to be moved a~ay from the surface
in the Z axis by means of actuator 22 in order to permit the
focussed light exiting from any transmittive state liquid
crysta~ cell's lens to impinge up~n the exposure surface at
an optically correct distance. The exposure routine is
recalled, and the same or different pattern is caused to b~
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13259~2
created by a repetition of the process described above. In
this case the initial position of gantry lg is not where X
is equal to zero but rather at the opposite end of its
travel along the X axis, at the displacement value (X =
X~axi~) where the previous scanning pass had ended. In order
to avoid wasting the time which would be required to drive
the gantry from X = Xmaxi~ to X = O, the routine initiates
exposure of the additional thickness by reading the outline
point records in reverse order, i.e. starting with the cell
transmittivity states at X = xDa~i~, then at X = XpreYio~ -
X, and so on until the gantry reaches the end of itsbackward travel at X = 0. At this point the routine once
again returns control of the machine back to the main
progr~m, which must determine anew if an additional
thickness is required and whether the above procedure is to
be repeated. Following the exposure and cure of the final
thickness, the pattern or article may be removed.
A case may arise, when a pattern is created in a liquid
wave-energy curing media, where the program determines that
an additional thickness of a different material or of a
different color is required. In such a situation the liquid
remaining from the previous exposure pass must be drained
from vessel 11 by means of a specific aperture among those
formed in fluid draining depressions 15a and 15b. The task
or removing liquid from the previous exposure surface is
assisted by the use of an air knife (not shown) mounted on
slide ~1. As the slide is caused to travel from the position
X - X~axi~ tG X = O, or vice-versa, the air knife is made
to operate by a command from the program activating a
solenoid valve, directing a planar shaped air flow in the
direction of surface 12, said flow in turn driving the
uncured liquid material towards depressions 15a and 15b.
According to the appended data of the record file, a
specific volume of the subsequent liquid is then pumped from
its reservoir into vessel 11, by means of the apertures in
depressions 15a and 15b, in order to provide a thickness of
material of the appropriate color and/or composition to act
as the current exposure surface. As the height of the new
material's exposure surface is not necessarily the same as
the previously exposed one, as measured by gage 38, the
program may cause slide 21 to be moved in relation to the
surface in the Z axis by means of actuator 22, in order to
permit the focussed light exiting from any transmittive
state liquid crystal cell's lens to impinge upon the new
exposure surface at an optically correct distance.
Obviously, if a sufficient number of thicknesses of the
previous exposure media have been cured and have attained a
great enough height in the Z axis, slide 21 may collide with
them as it is driven to the correct focussing distance: in
order to avoid such an occurence t~e ultimate number of
thicknesses of any given l~quid of a given color or type may
not be exposed in unbroken succession. ~ather, the program
determines, following its initial examination of the pattern
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record file, how many successive thicknesses of a given type
or color of liquid are to be cured in order to ~inimize the
number of draining and filling operations required by the
provisional alternation from one color or composition to
another. In between the draining and filling operations, the
exposure routine is recalled, and the same or different
pattern is caused to be created by a repetition of the
scanning process described previously. Upon surrender of the
routine's control of the machine back to the main program,
the latter must determine anew if an additional thickness of
material of the same or differing color and/or composition
is re~uired, and whether the above procedure is to be
repeated.
In the case where there exist Z axis height variations in
the actual target surface, e.~. where a wave-energy
sensitive material lies upon or is bonded to a substrate
exhibiting curvature along the X axis (such as a windshield
or other piece of curved glazing from a road vehicle), slide
21 must be incrementally displaced in the Z axis in order to
maintain an optically correct distance over the course of a
single exposure pass, from the minimum to the maximum value
of displacement in the X axis. As it reads the pattern
records and determines the appropriate signals to be sent to
the liquid crystal cells according to the instantaneous X
axis position, the program also reads the record's appended
field for Z axis height and issues a simultaneous command to
actuator 22 for the adjustment of slide 21's height
according to the latter's instantaneous X axis position.
According to yield or productivity requirements, a given
machine may be intended for use as a unit dedicated to the
~reation of patterns through the cure of a limited number of
thicknesses of wave-energy sensitive liquid of a limited
number of colors, where the absolute value of each color's
single thickness is not subject to close tolerances e.g. the
production of certain types of signage. In such a situation,
an alternative to the use of apertures (located in
depressions 15a and 15b) as the source of curable liquids of
various colors and compositions is the use of a series of
spray nozzles or atomization bells (ultrasonic,
electrostatic or other) placed upon slide 21 (this placement
is not shown). In such a configuration, slide 21 is called
upon initially to travel across the entire X axis exposure
area at an optimum Z axis height for the most efficent
atomized placement of the curing li~uid. Following such a
placement, slide 21's Z axis height is set, by means of
actuator 22, to a value corresponding to an esti~ated
opt cally correct distance for the curing of the deposited
liquid, and slide 21 is caused to travel again across the
entire X axis exposure area in order to create a pattern by
means of an implementation of the exposure routine described
previously. Removal of uncured excess wave-energy sensitive
liquid, prior to the deposition of an additional arbitrary
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17 132~912
thickness of a different color of a similar liquid, is
performed by means of an air knife, as previously described.
The excess liquid is drained, as in the previous case, by
sink apertures in depressions 15a and 15b. Thence, the
atomized placement of an additional arbitrary thickness of a
different color of a similar liquid takes place, the
exposure routine is repeated, and the entire process is
iterated until the completion of the desire~ product. Such a
means of akomized placement and pattern creation in wave-
1~ energy sensitive liquid is appropriate f~r substrates havingan essentially flat surface as well as those having Z axis
height variations in the actual target 3urface, e.g. where
the wave-energy se~sitive-liquid material is deposited upon
a substrate exhibiting curvature along the X axis.
Figures 4 and 5 illustrate how, in order to satisfy a
wide range of Y axis width constraints, two or more discrete
arrays of transvective liquid crystal cells may be combined
to form a continuous wave-energy shutter of compound design.
As liquid crystal cell arrays have certain end conditivns
and termination characteristics, abutting them end-to-end
results in an excessively great distance between the last
cell of the initial array and the first cell of the next
array. The use of such a compound array in the previously
described preferred embodiment would preclude exposure or
cure of those areas passing under the gap between the last
and first cells of adjoining discrete arrays. As shown in
Figure 4, in order to avoid such a gap between adjoining
arrays 71 and 72, these are placed upon slide 70 so that the
Y axis distance between the last cell of array 71 and the
first cell of array 72 is the same as that between two
contiguous cells in a single array. Additional discrete
arrays such as 73 can be affixed in a like manner, according
to the width of the supporting surface in question (e.g. the
appropriate width of slide 70, which is equivalent to slide
21 of Figure 1) and the Y axis exposure or curing breadth
required. Either a single sufficiently long source of
ultraviolet or near-ultraviolet light, or, several
individual sources specific to each discrete array, may
serve as the source of wave-energy for the compound array.
Obviously, the staggered placement of arrays 71, 72 and 73
induses an X axis offset between the colinear cell
centerlines of arrays 71/73 and the cell centerline of array
72 (cell centerlines along the Y axis). The magnitude of
this offset, Xoffset, is of the order of the width of ~n
array package or housing.
The staggered exposure effects of the compound array
offset can be corrected by several means. For the case where
so the discrete arrays are staggered, as in Figure 4, in such a
way as to be mounted normal to slide 21 and thus normal as
well to surface 12 of Figure 1 (i.e. so that the light
passing through their transmittive state cells impinges
perpendicularly up~n exposure surface 12), a time delay
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18 132~2
(given by the result of Xoffset divided by slide 21's X axis
velocity) is imparted to the cell transmittivity state
signals sent to the arrays which are non-leading, relative
to the immediate direction of motion along the X axis.
Figure 5 depicts an optical method of nullifying the effects
of the offset: the staggered arrays represented as elements
74 and 75 are affixed upon a slide 78 ~slide 78 is
equivalent to slide 21 of Figure 1) at angles about the Y
axis equal in magnitude but opposite in sign, so that the
light 76 passing tnrough their transmittive state cells
impinges upon exposure surface 77 (surface 77 is equivalent
to surface 12 of Figure 1) along a single line parallel to
the Y axis. In such a scheme the Z axis distance between
arrays 74/75 and the exposure surface 77 is of critical
importance in maintaining the separate beams of the
staggered arrays along a single line on surface 77.
In the presently preferred embodiment of this invention's
principles, the wave-energy generator affixed upon slide 21
is a non-columnated source of light within housing 34
emitting ultraviolet and/or near-ultraviolet wavelengths,
shuttered by an array of transvective liquid crystal cells
33. An alternative to the array of transvective liquid
crystal cells for the shuttering of the said light source is
an array of transvective electrochemichromic cells, whose
function and operation would essentially be the same. The
combination of a single light source with individually
addressable shutters can also be replaced by a high
resolution array of individually addressable light sources,
such as an array of light emitting diodes with or without
individual focussing lenses or fiberoptic guides. Figure 6
depicts a light emitting diode array 80, affixed upon a
slide 81 (slide 81 is equivalent to slide 21 of Figure 1).
Diodes emitting light at wavelengths particularly suited to
the curing of monomeric or oligomeric solutions now exist,
as well as linaar diode arrays having a density greater than
100 diodes per centimetre, each diode squipped with a
focussing lens or fiberoptic guide. Another alternative is
the use of a linear ~lectroluminescent or plasma display
system, suitable for use with wave-energy sensitive
mat~rials likely to be cured or exposed at the specific
wavelengths emitted by such systems, along with an array of
focussing lenses or fiberoptic guides. Any of ~hese
alternatives can be affixed upon a slide equivalent to slide
21 of Figure 1, in the form of staggered arrays or as a
single unit along the full required exposure breadth on the
Y axis, as a source of directed wave-energy for the creation
of an image or pattern, thus acting as an equivalent
replacement for the shuttered light source originally
described.
A slightly modified version of the presently preferred
embodiment makes use of a solid phase fluid naterial instead
of a liquid for the creation of thick patterns. A
y
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lg 132~912
homogeneous admixture of a finely ground material of stable
nature with a wave-energy sensitive binder ls used as a
substitute for the wave-energy sensitive liquids described
previously. The particles may be of an organic or inorganic
nature, either thermoset or thermoplastic; the binder may be
a wave-energy sensitive uncured liquid phase material, such
as a momomer/oligomer resin or adhesive, or a thermoplast in
liquid or solid phase. The characteristics and functions of
such an admixture are similar to those of the powdered ink
or toner material utilized in several types of xerographic
process machines. Figure 7 depicts a slide 90 which, for the
use of a solid phase material, replaces slide 21 of the
machine shown in Figure 1. The admixture passes through
small distribution hoppsrs 92a and 92b, having been
retrieved from a remote reservoir by means of a material
handling system (not shown). As slide 90 is driven in the X
axis, the admixture is uniformly distributed in front of the
slide through the wide gate of the hopper, 92a or 92b, which
is foremost in the direction of ~ravel. The admixture is
further spread into an even planar layer of regular
thickness by rectilinear plow blades 91a and 9~b, which
displace any excess material away from the exposure surface
(an alternative to such blades are cylindrical rollers of a
radius equivalent to the thickness of the said blades, said
rollers fulfilling the task of spreading and displacing the
admixture). The Z axis depth to which blades 91a and 91b
extend beyond the bottom surface of slide 90 is dependent
upon the mean particle size and wave-energy sensitivity of
the admixture, and is thus adjustable. As slide 90 passes
over the just spread thickness of admixture, the wave-energy
beam generator it carries causes a selective curing or
exposure of the admixture thickness, thus creating a
pattern, much as would occur in the previously described
case of a thickness of wave-energy sensitive liquid. The
curing process continues until slide 90 reaches the end of
its travel. If the control program determines that an
additional thickness of admixture, of the same or differing
composition and/or color, is to be cured in the same or
different pattern, the opposite hopper and blade will be
used to deposit and smooth out the selected admixture for
exposure as slide 90 returns in the opposite direction of
travel. The consecutive curing of admixture thicknesses
continues until the end of the pattern's records file is
reached.
Arl abreviated and general pattern forminq method for the
presently preferred embodiment is as follows:
1. Design a pattern or article.
2. Transform the above design into a pattern description
format compatible with the apparatus.
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13259~2
3. Edit the pattern data and append material type(s) as
well as color(s), as required.
4. Transfer said edited pattern data into computer
storage.
5. Execute the exposure program, which performs the
following functions:
initializes apparatus operations, including:
review of position of gantry and slide,
review of media height in exposure vessel as well
as in media reservoirs, and
review of other pertinent variables;
prompts user for said pattern data filename,
reviews and analyzes said pattern data, for:
an evaluation of the capacity of said apparatus to
create said pattern described by said pattern data,
an evaluation of the required types and quantities
of said fluidized wave-energy sensitive media in
said specific reservoirs,
an evaluation of the required film or substrate
type(s) in said apparatus,
an evaluation and optimization of exposure
schedule(s) for the curing of multiple thickness
patterns of several fluidized material types, and
an evaluation of other pertinent requirements of
said apparatus;
reports to the user the above status of said apparatus
and its current requirements, including:
a request for permission to correct the position of
said gantry and said slide, as well as other
pertinent conditions of said apparatus,
a requ~st to said user to place sufficient
quantities of said fluidized wave-energy sensitive
media in said specific reservoirs,
~Q
a request to said user to place required film or
substrate type in said apparatus, and
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21 t 3 2 3 9 1 2
a request to correct other pertinent requirements
of said apparatus;
prepares exposure conditions, as appropriate,
including:
the activation of said linear image generator in a
non-transmittive state,
causing a specified amount of said wave-energy
sensitive fluidized media to be placed upon said
exposure surface, and : .
causing said non-reactive gas to be introduced into
said exposure vessel,
causes exposure/cure to take place by calling upon a
patterning routine, which includes:
a verification that pertinent exposure conditions
are satisfied,
the input of the first lineal image data,
an initiation of continuous gantry displacement and
displacement travel monitoring, and
: ~ the setting and resetting of linear image generator transmittivity according to instantaneous gantry
displacement and line image records, until all .
lineal image data is exhausted;
: determines whether additional thicknesses are
required, and if so, iterates exposure condition
preparation and patterning routine call-up until the
pattern or article is completed, -
returns gantry to origin,
prompts said user for removal of said pattern or
article, and,
prompts said user for next pattern data filename or
for a request to exit from patterning activity.
As shown above, many embodiments and alternative
configurations of the described apparatus and control
methods may be used to implement the principles of the
present invention. However, they all have in co~mon the
- 50 concept of creating patterns in a wave-energy sensitive
material, of one or several thicknesses, by passing over the
material once or several times along one axis with an
exposure device in the form of an instantaneously
modulative, high resolution rectilinear source of discrete
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22 13~
beams of wave-energy, where the said material may be of
several natures, such as film, liquid, or a flowable solid,
and, during the course of the formation of a thick pattern
or article prepared from a wave-energy sensitive fluidized
material, the cured interstices of the thick pattern or
article remain static, and each individual interstice or
part thereof may be of the same or differing composition and
color. The aforestated comprehensive description is
presented by way of example and illustration only, the scope
and spirit of the present invention being limited merely by
the attached claims.
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