Shock absorber cushion for flexographic printing plate and method of use

A sheet of elastomeric material that serves as a shock absorber and cushion for use between a flexographic printing plate and a printing cylinder during printing for compensating for variations in thickness, height and centricity of the printing cylinder and flexographic printing plate to prevent distortions in the image being printed that includes providing an elastomeric sheet having a longitudinal direction in the direction of circumferential travel of the cylinder circumference that includes a plurality or array of protrusions formed of the elastomeric material of predetermined cross-sectional shape and area and the material having a durometer to cushion the flexographic plate in such a way to provide the necessary compensation to ensure a high quality printed image at high speed. The cross-sectional shapes and the array of the longitudinal protrusions provide for material displacement zones that allows the elastomeric material to be compressed and return relatively instantaneously to its original height or near original height in sharing high quality printing compensating for tolerance errors between the drum size and the flexographic plate thicknesses.

BACKGROUND OF THE INVENTION
 1. Field of the Invention
 This invention relates to a shock absorber and cushion for use between a
 flexographic printing plate and a printing cylinder during printing that
 compensates for variations in thickness, height and centricity of the
 materials and equipment used for printing to enhance the image quality and
 efficiency of the flexographic printing process without increasing
 printing pressure.
 2. Description of Prior Art
 Flexography is a printing process used primarily in the packaging and
 newspaper industries. The flexographic process requires that a raised
 surface plate be used to transfer ink onto a given substrate. This is
 unlike lithography, which works on a flat plane based on the principle
 that oil and water do not mix. The gravure printing process is a recess
 process in which cells are engraved into the print cylinder that are then
 filled with ink and then transferred to the substrate.
 The flexographic printing process' unique capabilities include changing
 cylinder dimension (circumference) to accommodate As in most manufacturing
 and machine processes, there is a plus or minus tolerance in gauge
 (thickness) uniformity which may include: the print cylinder uniformity,
 both across and around the web; a tolerance in the material surface being
 printing on; and, the tolerance of the back cylinder which the substrate
 rides on as it maneuvers through the press in addition to other mechanical
 elements. Variations in tolerances require excessive pressure during
 printing on the flexographic plate to overcome inaccuracies which may
 smear and distort the print image such as halos and oval dots.
 Currently the raised imaged carriers (flexographic plates) adhere to a
 print cylinder using various methods which include clamps, pins, vacuum
 and most commonly, an adhesive tape applied to a flat seamless cylinder.
 There are various types of adhesive tapes used to adhere the flexographic
 printing plate to the cylinder. Although there are many variations of
 adhesive tape materials available, the materials used are routinely lumped
 into the following three categories:
 (1) Hard Tape--no significant or claimed cushioning affect. This tape is
 best used when large amounts of ink need to be applied at 100% strength
 (full strength). However, since this tape has no inherent ability to even
 out the mechanical tolerances of the printing press, more than minimal
 pressure is normally required. This pressure creates a distorted printed
 image appearing in various forms which may include hard edges around the
 outer portion of the line copy while leaving a halo adjacent to this hard
 edge. Depending upon impression required, text may be squeezed to a point
 where it begins to slur (elongated the print in a through-press
 direction).
 (2) Soft Tape--used as a cushion to allow even impression across and around
 the cylinder. This is because soft foam tape collapses or compresses under
 pressure in the areas that come into impression first which represent the
 largest circumference of the print package and must be impressed several
 thousands more until the entire image appears to be printing evenly and
 uniformly. Because of its softness, this material is used primarily when
 fine details or extremely small images are printed to help minimize the
 distortion that occurs under pressure with hard tape. Soft tape is
 traditionally used when printing half tones for screened pictorials,
 gradations and screen tints. Due to the soft nature of this cushioning
 element, the amount of pressure required to transfer a solid image is
 significantly compromised.
 (3) Medium tape used as a cushioning element considered to be of medium
 density. Medium tape is a compromise between the attributes of a soft tape
 used for printing fine graphics, and, hard tape used for images which need
 to print robust solids on the same printing surface using the same
 cushioning material.
 The present invention eliminates or minimizes the negative attributes of
 the tape product(s) described above available today. This includes
 inconsistency in gauge of the raw material currently available which is
 said to vary by plus or minus several thousands of an inch. With foam
 technology, foam cells or voids are filled with air, and during
 impression, under high spots, air is forced away and needs time to return
 to cells and thus return to initial tape height or dimension prior to the
 next revolution of the press. Cell inflation delay requires the press to
 run at lower speeds when working with a softer foam tape, soft or medium.
 The slower drum speeds provide the time for the foam cell tape material to
 rebound between successive impressions. Throughout a very long print run,
 the adhesive tape material gradually loses ability to rebound. Constant
 monitoring is required throughout the run and most often results in color
 shifts and unacceptable print at some point in time, which is normally
 over one million impressions--but in most cases not greater than three
 million impressions.
 U.S. Pat. No. 3,285,799 discloses a printing blanket for long periods of
 use in offset lithography which is composed of a polymeric film and woven
 backing, an ink transfer layer, and a resilient compressible support
 layer. The support layer has an external surface subdivided by grooves
 which leaves flat surfaced islands. The blanket is used as an intermediate
 to transfer an ink image from a printing plate to paper. The support layer
 has a durometer of at least 60 Shore A. The support layer contains at
 least about 0.005 cubic inches of voids per square inch of blanket surface
 but total void volume does not exceed 40%.
 U.S. Pat. No. 5,325,776 discloses a cushioning backing sheet metal material
 positioned between a flexographic printing cylinder and a flexible
 printing plate. The cushioning sheet is an elastomeric material containing
 widely spaced, closed cell voids which provide pockets within which the
 encapsulated air can be pneumatically compressed when force is applied,
 and which all rebound rapidly when the force is relieved. A disadvantage
 of the closed-cell cushioning material fatigues and looses compression and
 resilience qualities, and thus print quality deteriorates.
 BRIEF SUMMARY OF THE INVENTION
 A shock absorber and cushion for use directly or indirectly under a
 flexographic printing plate in order to compensate for variations in
 thickness, height and centricity of the printing cylinder and flexographic
 plate during the printing process. The invention includes a sheet of
 elastomeric material sized to be placed around the printing plate
 cylinder, said elastomeric sheet having predisposed displacement zones
 resulting from creating voids within the elastomeric material of
 predetermined thicknesses of the material sheet providing a path of least
 resistance for the displacement material for maintaining an even
 impression along the flexographic plate both across and around the
 printing plate cylinder.
 The sheet of elastomeric material includes a predetermined geometric
 pattern that define the displacement zones which are essentially
 circumferential in direction, i.e. linear raised protrusions that extend
 in the direction of the printing path and that can be in parallel rows,
 spaced apart, circumferentially around the printing cylinder and in the
 direction of the printing drum rotation. The elastomeric sheet in
 accordance with the present invention has a plurality or an array of
 spaced-apart zone displacements of a predetermined geometrical
 cross-sectional shape and size which are preferably in a parallel array in
 the direction of the rotation of the printing cylinder (substantially
 circumferential) relative to the printing cylinder. The spaced apart
 displacement zones allow the elastomeric material to be radially displaced
 to accommodate variations in thickness, height and centricity of both the
 flexographic plate and the print cylinder to which it is mounted.
 The linearity of the protrusions could vary somewhat perhaps to around
 45.degree.. The geometric pattern is designed to deliver varying amounts
 and levels of displacement or compression resistance thus controlling the
 impression required for fine graphics and the resilience necessary to
 print large solids. By way of example, most, if not all, geometric shapes
 in view will provide the necessary displacement zone. The displacement
 zone is a combined product of the geometric cross-sectional area and shape
 itself and is greatly influenced by the distance placed between these
 protrusion elements as well as the durometer of the elastomeric material.
 It is important that any geometric shape run (with or without break)
 in-press direction around the print cylinder. The press direction is
 described as the direction the printed material travels through the press.
 The importance of putting this geometric shape in-press direction creates
 the path of most resistance for displacement around the cylinder forcing
 the displacement across the cylinder in such a way as to not distort the
 printed image.
 The cushioning element is compromised of two layers: one is the base layer
 which consists of any metallic or polymeric film material which is
 dimensionally stable; or, MYLAR that is no less than 0.002 in thickness
 and without a limit to maximum thickness. This material is used as a
 stabilizing base for the second layer which contains the geometric
 protrusion array made of elastomeric material of a predetermined durometer
 whose resilience at normal operating temperatures will deform and fill the
 adjacent displacement areas under various amounts of stress. The
 cross-sectional shape of each protrusion strip may be a trapezoid by way
 of example. The strips are parallel spaced apart at a predetermined
 distance and across the cylinder width. Suitable elastomeric materials
 include, but are not limited to, polybutadience, polyisoprene,
 polychloroprene; and olefin copolymers such as styrene-butadiene
 copolymers, nitrile rubbers (e.g. acrylonitrile-butadiene copolymer),
 ethylene-propylene copolymer, and butyl rubber (e.g., isobutylene-isoprene
 copolymer). Elastomers which are thermoplastic are also suitable as the
 cushion layer and include, but are not limited to, styrenediene-stryene
 triblock copolymers, such as polystyrenepolybutadiene-polystyrene (SBS),
 polystyrene-polyisoprene-polystyrene (SIS, or polystyrene-poly
 (ethylenebutylene)polystyrene (SEBS); thermoplastic polyester and
 polyurethane elastomers; and thermoplastic polyolefin rubbers (polyolefin
 blends). Suitable elastomers also include chlorosulfonated polyethylene,
 polysulfide, polyalkylene oxides, polyphosphazenes, elastomeric polymers
 and copolymers of acrylates and methacrylates, and elastomeric copolymers
 of vinyl acetate and its partially hydrogenated derivatives.
 In an alternate embodiment, the layer of elastomeric material can also be
 compromised of multiple layers with different Shore A hardness. Each
 circumferential protrusion could be made of two or more layers of
 materials of different durometers to further efficiently control the
 resistance. The required resistance may vary and be altered to respond to
 the various print market such as corrugated, news print, poly/plastic
 sheets and paper which may require different rsistances. Being able to
 control these individual factors, a wide range of refinements for various
 cushioning requirements are possible. These protrusions from top to base
 formed from the elastomeric material should be greater than 10% of the
 total volume from floor to ceiling and should not exceed 80%. The most
 preferable ratio is between 15% and 50% volume of material to displacement
 void. The area adjacent the protrusion material mass shall be considered
 displacement void zones. The embodiment of this displaceable protrusion
 material is currently created by using photopolymer plate material from
 various manufacturers including but not limited to DuPont's "Cyrel.RTM.",
 Polyfiberons' "Epic.RTM." and BASF's "NyloFlex.RTM." photopolymerizable,
 photocrosslinkable or both. The photopolymerizable layer compromises an
 elastomeric binder, at least one monomer and an initiator, where the
 initiator is preferably a photoinitiator having sensitivity to actinic
 radiation. Any photopolymerizable compositions which are suitable for the
 formation of flexographic printing plates can be used for the present
 invention. Examples of suitable compositions have been disclosed, for
 example, in Chen et al, U.S. Pat. No. 4,323,637, Gruetzmacher et al, U.S.
 Pat. No. 4,427,749 and Feinbert et al., U.S. Pat. No. 4,894,315.
 The processes available to manufacture the cushion include laser engraving,
 mechanical engraving, molding vulcanized rubber, extruding and other
 current technologies.
 The cushion is mounted between the plate cylinder surface and the
 flexographic plate base. The cushion may be glued to the cylinder surface
 and to the flexographic plate surface. Alternatively, sticky tape may be
 used to attach the cushion with adhesive to the drum cylinder and also to
 the flexographic plate surface.
 The cushion may be mounted so that the protrusions engage the bottom of the
 flexographic plate or conversely such that the protrusions engage the
 surface of the plate cylinder. In the preferred embodiment, the
 protrusions would engage the print cylinder surface and be essentially
 inverted relative to the flexographic plate surface. Whether upside down
 or right-side up, depending on the point of view, it is important that the
 protrusion strips must be disposed to run parallel or in the direction of
 the circumferential drum rotation. The cushion material could also be used
 with any other flexographic plate mounting system that may include vacuum,
 clamps, sleeves, pins or other mechanical attachment.
 The cushion, in accordance with the present invention, can be mounted onto
 the plate cylinder with adhesive, glue or double-sided adhesive tape.
 Thus, the cushion is directly against the printing plate, or indirectly,
 if you consider that glue or adhesive tape holds the cushion to the
 cylinder and to the printing plate.
 In alternate embodiments, the cushion and protrusions could be extruded on
 the back of the flexographic printing plate so that it becomes part of the
 printing plate itself. In that case, the cushion and plate would be
 together as one single entity and then would be mounted by adhesive or
 other fastener onto the print cylinder. It is also in another embodiment
 possible that the plate cylinder surface itself could include permanently
 a particular cushion. And yet another possible alternate embodiment would
 be that the cushion is actually a cylindrical sleeve that is stretched
 over and placed on the print cylinder surface that can be put on and off
 as a sleeve.
 It is an object of this invention to provide an improved cushion or shock
 absorber for use in the flexographic printing process to compensate for
 variations in thickness, height and centricity of the materials and
 equipment used in flexographic printing to enhance image quality and
 efficiency without increasing printing pressure which distorts the
 ultimate printed image.
 It is another object of this invention to provide a cushion between a
 flexographic plate and printing drum that retains its resiliency without
 fatigue over extremely long printing runs without reducing image quality.
 In accordance with these and other objects which will become apparent
 hereinafter, the instant invention will now be described with particular
 reference to the accompanying drawings.

PREFERRED EMBODIMENT OF THE INVENTION
 Referring now to the drawings, and in particular FIG. 1, the present
 invention, which is used as a shock absorber or cushion, is shown
 generally at 10 comprised of a sheet of elastomeric material 12 that is
 shown positioned above a plate cylinder 14 having a surface 16 that is
 used with a flexographic plate, (not shown in FIG. 1) for printing. In the
 operating position, the elastomeric sheet 12 is in fact disposed around
 the circumference of cylinder 14 and may be glued or otherwise fixed to
 the cylindrical surface 16 around the drum. A double-sided stickback
 adhesive sheet can be employed to affix the cushion to the drum. The arrow
 shows the direction of the drum rotation and also, therefore, the
 direction of the elastomeric sheet 12 in operation. In the preferred
 embodiment, the protrusion strips engage the drum surface.
 A flexographic printing plate used for printing is affixed (glued) on top
 of cushion 12. Therefore, the elastomeric sheet 12 acts as a shock
 absorber or cushion between the drum surface and the flexographic printing
 plate which is attached by glue on top of the cushion 12.
 Once the plate and cushion 12 are installed, the flexographic printing
 process would then proceed as normal. If the cylinder 14 has tolerance
 errors in diameter or if the thicknesses of the flexographic plate vary
 from the ideal norm, the cushion 12 allows for compressive displacement to
 allow equal pressure on the flexographic plate during its operation of
 printing so that the final printing does not have flaws (bright/dark spots
 or slur). Because of the compressive displacement of the cushion 12,
 excessive printing pressure on the plate is not necessary that would
 otherwise distort the image forming elements.
 Referring now to FIG. 2, the elastomeric sheet 12 is shown (partially cut
 away as a segment) that is comprised of a MYLAR support base 18 that has a
 plurality of trapezoidally-shaped (in cross-section) photopolymer
 elastomeric protrusions 20 which are attached to MYLAR sheet 18 and are
 essentially parallel strips in a parallel array and spaced apart by a
 predetermined distance as shown by area 22 that separates adjacent
 protrusions 20.
 Each trapezoidally-shaped protrusion 20 includes a small flat top surface
 24 that is parallel to the top surface of support base 18, a pair of
 converging sidewalls 28 that converge to the top wall 24 and a bottom wall
 26 affixed to base 18.
 The cushion 12 is comprised of a cushion layer of elastomeric material
 forming protrusions 20 and the MYLAR support base 18. The total volume of
 material occupied by each protrusion 20 and one adjacent void whose base
 is shown as surface 22 define a displacement zone which allow for vertical
 compression or displacement of each protrusion area into adjacent void
 space between the protrusions. When looking at a cross-section
 perpendicular to the movement of cushion 12 defined by arrow A along the
 drum surface, the cross-section across the width of the cushion shows the
 trapezoidal-shaped faces of the protrusion and a likewise
 trapezoidally-spaced void between protrusions. The dimensions of each
 protrusion, including the length of the top, the converging sidewalls, the
 base 26 and the displacement adjacent space which includes surface 22 and
 diverging walls between adjacent protrusions and the distance between the
 tops of adjacent protrusions are selected to meet a predetermined material
 to displacement zone of 30%-90%. Therefore, the area of the trapezoid
 forming a protrusion 20 would be approximately 10%-70% the entire area
 occupied by one trapezoid and one adjacent void area. The cross-sectional
 shape of each protrusion, perpendicular to the direction of travel, can be
 varied and is discussed in greater detail below. Also the protrusions are
 in straight lines, some lateral displacement such as a zigzag or slightly
 s-shaped strip with deviations less than 450 may be tolerated relative to
 the straight line direction of travel indicated by arrow A.
 The protrusions 20 are formed from a sheet of photopolymer material using
 known technology and can be of different geometric configurations as
 discussed below. The displacement necessary to be an effective shock
 absorber is figured by the pressure where a flexographic plate 30, as it
 rests on the top wall 24 of each of the protrusions, would be compressed
 by variations and errors in the centricity of the drum or the variations
 in the thickness of the flexographic plate 30 during operation or during
 the printing process itself.
 The purpose of the invention is to allow sufficient displacement vertically
 between the drum and the flexographic plate 30 that the elastomeric
 material, and in particular the protrusions 20, can be compressed or
 deformed downwardly and also return to their static position without wear
 or stress. The shape in cross-section, which would be perpendicular to the
 direction of arrow A as shown, of each protrusion 20, the specific
 dimensions of the base, the top, the sidewalls, and the spacing between
 protrusions along the base and the top wall, are factors in determining
 the amount of ultimate displacement therefore controlled resistance that
 occurs between the cylinder 14 and especially the drum surface 16, as
 shown in FIG. 1, and a flexographic plate 30, as shown in FIG. 2. It is
 important that the protrusions 20 have a longitudinal access in the
 direction of arrow A, which is also the circumferential direction of the
 drum movement during the printing operation. Under low stress at room
 temperature, the elastomeric protrusions will return to its original or
 near original height or gauge for extended printing runs.
 FIG. 3 shows a top plan view of the elastomeric sheet 12 and the spacing 22
 between adjacent protrusions 20. Also shown in FIG. 3 is the width of the
 top wall of protrusion 20 and how they are parallel to each other and
 spaced uniformly in strips across the entire width of cushion 12. Arrow A
 represents the direction of travel so that the cushion 12, as shown in
 FIG. 3, would actually be wrapped around the drum with the protrusions 20
 oriented in the direction of rotation of the drum circumferentially and in
 the direction of arrow A. Therefore, the width of the sheet 12 would
 constitute and be determined by the width of the drum itself. The printing
 drums do vary in size and width and in diameter, and the cushion would be
 manufactured in sufficient lengths and widths to accommodate drums of
 different diameters and widths. Also the spacing 22 between each
 protrusion helps define the total displacement area available.
 FIG. 4, again, shows the relationship between protrusions 20, which are in
 an adjacent parallel array. Each protrusion 20 includes a flat top wall
 24, a base 26 longer than the top 24 and the spacing 22 along the entire
 sheet base 18. In operation a flexographic plate 30 is glued to the MYLAR
 support base 18 and the drum surface is glued against each of the top
 walls 24 of all of the protrusions 20. The sheet 12 may be inverted in
 operation such that the mylar base 18 is glued against the drum surface.
 In an alternate embodiment, the cross-sectional shape of the protrusions
 could be varied to something like shown in FIG. 5, which is a modified
 trapezoid that includes sidewalls 34 and 34A that converge along the top
 wall 36. Again, a flexographic plate 30, such as shown in FIG. 4, could
 rest along the top wall surfaces 36 in each of these protrusions so that
 displacement would be a downward compression between the flexographic
 plate 30 and a drum that would be along the bottom surface of 32 or the
 cushion could be inverted as discussed above.
 Print cylinders vary in both width and circumference. The circumferential
 range of print cylinders are available in circumferences from less than 6
 inches to over 40 inches. Dimensions of print cylinders change
 circumferentially based on the package repeat or length. Flexography uses
 a raised plate of varying thickness, ranging from 0.03 inches or less to
 greater than 0.155 inches. In the prior art, the adhesive/foam tape that
 was available came in different thicknesses and when the print cylinder or
 sleeves are ordered, the overall height of elements adhere to the cylinder
 plate or attached by a sleeve must be a known and consistent overall
 height. The tolerance for this variation is known as "cylinder undercut".
 One of the purposes of this invention is to provide an overall buildup of
 elements adhered to a print cylinder that add up exactly toward the proper
 undercut. Therefore, if in an example, a plate were 0.067 inches and the
 blanket were 0.020 inches, the undercut would be 0.087 inches. With the
 present invention, the plate would be 0.045 inches and an adhesive plate
 to blanket would be 0.002 inches while the blanket itself would be 0.030
 inches and the adhesive blanket to the cylinder would be 0.010 inches.
 This would result in an undercut of 0.087 inches.
 In accordance with this invention, there is a direct relationship between
 the elastomeric material durometer, the shape of the protrusion or
 displaced element, the materials height, shape and area of displacement.
 All tests to-date have involved wide-web presses thirty (30) inches and
 wider printing on a plastic polymer. A change in protrusion height,
 geometric shape of the elements, the durometer of the displacement
 material in addition to changes in the displacement zone may require
 further modifications which could be determined by each market segment,
 namely the print medium to be used in the printing process.
 EXAMPLE
 The characteristics in accordance with this invention were tested with
 displacement projections that were in straight line ranging in widths of
 0.001 inches to approximately 0.3 inches. The second characteristic of the
 pattern used is the spacing between images. The present invention in
 experiment realized various levels that were successful when the void
 space was at least equal to the materials' surface image with spaces as
 great as ten times the image width. In accordance with this example, the
 most preferable image top width was 0.004 inches while maintaining a space
 between images of 0.042 inches. This creates an image support that, at its
 most narrow point, was 0.004 inches in expanding in width from the top of
 the blanket to the mylar base approximately 0.021 inches.
 It is important that regardless of the geometrical cross-sectional shape
 that the protrusion element run essentially circumferentially, preferably
 without a break in the circumferential direction around the print
 cylinder, that is the press direction. The press direction is described as
 the direction the printed material travels through the press. The
 importance of putting this geometrical shape in the press direction
 creates the path of most resistance for displacement around the cylinder,
 forcing the displacement across the cylinder in such a way as to not
 distort the printed image. Small breaks (not full depth) in the protrusion
 strip element in the circumferential direction may be permitted for a
 specific configuration.
 Referring to FIG. 6, the cushion or shock absorber 12 is comprised of two
 layers. The first layer 18 is a dimensionally stable support base layer of
 MYLAR, metal, fabric, composite, or alternate flexible material or
 polymeric film material, which is dimensionally stable or MYLAR that is no
 less than 0.002 inches in thickness and without a limit to maximum
 thickness. The first layer 18 is used as a stabilizing base for the
 photopolymer second layer 20, which contains the elastomeric material and
 the plurality in array of circumferential protrusions whose resilience at
 normal operating temperatures will deform and fill the adjacent
 displacement areas under various amounts of compression or stress. They
 elastomeric protrusions return relatively instantly and rapidly to the
 original or near original dimension when the compression pressure is
 removed. The second layer 20, which is the elastomeric material, can be
 comprised of multiple layers with different Shore A hardness.
 The protrusions in cross-sectional areas formed from the elastomeric
 material should be greater than ten percent (10%) of the total
 cross-sectional area from top 24 to the base 26 and should not exceed
 seventy percent (70%). The most preferable ratio is between fifteen and
 fifty percent (10%-70%). The area comprising the rest of the material mass
 shall be considered displacement zones or voids.
 FIG. 7 shows a pair of protrusions 25 as an example that has, from top to
 bottom, different layers of material of different durometers which would
 be used to control the effect of cushion resilience. The multi-layers of
 varying durometer would thus control initial displacement zone and the
 effective overall cushion resilience. The dotted line show the proposed
 displacement from a vertical or top down compression caused by tolerance
 errors in the printing equipment as discussed above. Thus, it can show
 that each area would have a different displacement, but the sum total
 would be at some desired total displacement.
 Referring now to FIG. 8, a plurality of different cross-sectional
 representative shapes for the protrusion strips are shown schematically
 that represent the possible cross-section of the protrusions as they are
 attached to the MYLAR sheet. The compression displacement expected is
 shown as dotted lines indicating displacement of adjacent protrusions in
 operation. In FIG. 8A, rectangles are shown and the dotted portions are
 shown curved due to downward compression on these elements.
 In FIG. 8B, trapezoids are shown that compress (as shown dotted), and they
 may contact each other.
 FIG. 8C shows a pair of ovals that can expand sideways (as shown dotted)
 for the displacement from top down.
 FIG. 8D shows a pair of circular protrusion elements that can expand (as
 shown dotted).
 FIG. 8E shows a pair of isosceles triangles spaced apart and the
 anticipated displacement (as shown dotted).
 FIG. 8F shows a pair of protrusions having a flat top portion somewhat
 arcuate sidewalls that can expand (as shown dotted).
 FIG. 8G shows elliptical protrusions or oval shape protrusions with their
 longer access being vertical and disposed adjacent each other (as shown
 dotted) showing the displacement.
 FIG. 8H shows six-sided figures with shorter edges at the top than the
 bottom, which are polygons, which would be next to each other (as shown
 dotted).
 FIG. 8I shows octagons and the resulting displacement as shown dotted.
 FIG. 8J shows protrusion elements that are star shaped in the top portion
 and the displacement expected as shown dotted.
 FIG. 8K shows somewhat arcuate protrusions with flat tops on them placed
 adjacent each other with the dotted lines showing compression
 displacement.
 FIG. 8L shows two somewhat circular cross-sectional units joined
 end-to-end, from top to bottom, and the dotted lines show the anticipated
 displacement during compression.
 FIG. 8M shows circular center bodies with rectangular tops and bottoms for
 protrusions, and the dotted lines show the anticipated compression.
 Referring back to FIG. 6, the preferred embodiment of the invention is
 shown to provide specific dimensions such as approximately 0.063 inches
 from center-to-center of each adjacent protrusion with the base of each
 protrusion being approximately being 0.021 inches in width at its base,
 and the spacing between protrusions along the base portion be 0.042
 inches. The dimensionally stable carrier 18 is 0.007 inches. The top wall
 24 is 0.004 inches approximately.
 FIGS. 9 and 10 show the invention in which (during printing) the cushion 12
 is positioned such that the tops 24 of the protrusions are affixed to the
 print drum/cylinder surface 16 while the support 18 would be glued to the
 flexographic printing plate 30. The cushion 12 remains the same in all
 structural respects.
 In summary, controlling the displacement longitudinally along the direction
 of the print drum travel with a continuous, or almost continuous, element
 in a parallel array has been found to greatly improve the shock-absorbing
 characteristics between the flexographic plate and the drum to greatly
 increase the accuracy and clarity of the printed material with longer runs
 because the material does not have to be replaced as often as the prior
 tape used for this purpose before. Variations will be possible in the
 geometric shape, the durometer and geometric configurations to vary the
 displacement based on a particular type of job and material or print
 medium required.
 The instant invention has been shown and described herein in what is
 considered to be the most practical and preferred embodiment. It is
 recognized, however, that departures may be made therefrom within the
 scope of the invention and that obvious modifications will occur to a
 person skilled in the art.