Silicone and phosphate ester slipping layer for dye-donor element used in thermal dye transfer

A dye-donor element for thermal dye transfer comprising a support having on one side thereof a dye layer and on the other side a slipping layer comprising a lubricating material dispersed in a polymeric binder, the lubricating material comprising a partially esterified phosphate ester and a silicone polymer comprising units of a linear or branched alkyl or aryl siloxane.

This invention relates to dye-donor elements used in thermal dye transfer, 
and more particularly to the use of a certain slipping layer, comprising a 
lubricating material dispersed in a polymeric binder, the lubricating 
material being a partially esterified phosphate ester and a silicone 
polymer comprising units of a linear or branched alkyl or aryl siloxane, 
on the back side thereof to prevent various printing defects and tearing 
of the donor element during the printing operation. 
In recent years, thermal transfer systems have been developed to obtain 
prints from pictures which have been generated electronically from a color 
video camera. According to one way of obtaining such prints, an electronic 
picture is first subjected to color separation by color filters. The 
respective color-separated images are then converted into electrical 
signals. These signals are then operated on to produce cyan, magenta and 
yellow electrical signals. These signals are then transmitted to a thermal 
printer. To obtain the print, a cyan, magenta or yellow dye-donor element 
is placed face-to-face with a dye receiving element. The two are then 
inserted between a thermal printing head and a platen roller. A line-type 
thermal printing head is used to apply heat from the back of the dye-donor 
sheet. The thermal printing head has many heating elements and is heated 
up sequentially in response to the cyan, magenta and yellow signals. The 
process is then repeated for the other two colors. A color hard copy is 
thus obtained which corresponds to the original picture viewed on a 
screen. Further details of this process and an apparatus for carrying it 
out are contained in U.S. Pat. No. 4,621,271 by Brownstein entitled 
"Apparatus and Method For Controlling A Thermal Printer Apparatus," issued 
Nov. 4, 1986, the disclosure of which is hereby incorporated by reference. 
A problem has existed with the use of dye-donor elements for thermal 
dye-transfer printing because a thin support is required in order to 
provide effective heat transfer. For example, when a thin polyester film 
is employed, it softens when heated during the printing operation and then 
sticks to the thermal printing head. This causes intermittent rather than 
continuous transport across the thermal head. The dye transferred thus 
does not appear as a uniform area, but rather as a series of alternating 
light and dark bands (chatter marks). Another defect called "smiles", 
which are crescent shaped low density areas, is produced in the receiving 
element by stretch-induced folds in the dye-donor. Another defect is 
produced in the receiving element when abraded or melted debris from the 
backing layer builds up on the thermal head and causes steaks parallel to 
the travel direction and extending over the entire image area. In extreme 
cases, sufficient friction is often created to tear the dye-donor element 
during printing. It would be desirable to eliminate such problems in order 
to have a commercially acceptable system. 
European Patent Application No. 138,483 relates to dye-donor elements 
having a slipping layer on the back side thereof comprising a lubricant in 
a resin binder along with particulate material. A large list of 
lubricating materials is disclosed including various silicone and 
fluorine-containing surface active agents. The use of those materials in 
combination is not specifically taught, however. In addition, the slipping 
layer in that publication has a rough surface due to the presence of 
particulate material in order to prevent the dye-donor sheet from sticking 
to the thermal printing head. Such particulate material could have an 
abrading effect on the printing head, however, and is undesirable for that 
reason. 
U.S. Pat. No. 4,567,113 also relates to dye-donor elements having a 
slipping layer on the back side thereof comprising various materials 
including phosphoric acid esters. European Patent Applications Nos. 
163,145 and 169,705 also disclose various materials for slipping layers 
including compounds having a perfluoroalkyl group, silicone materials and 
fluorine-containing surface active agents. There is no disclosure in these 
references, however, of the use of the combination of materials taught by 
this invention to improve the performance of the slipping layer. 
Accordingly, this invention relates to a dye-donor element for thermal dye 
transfer comprising a support having on one side thereof a dye layer and 
on the other side a slipping layer comprising a lubricating material 
dispersed in a polymeric binder, and wherein the lubricating material is a 
partially esterified phosphate ester and a silicone polymer comprising 
units of a linear or branched alkyl or aryl siloxane. 
In a preferred embodiment of the invention, the silicone material is 
present in an amount of from about 0.0005 to about 0.05 g/m.sup.2, 
representing approximately 0.1 to 10% of the binder weight, the phosphate 
ester is present in an amount of from about 0.001 to about 0.150 
g/m.sup.2, representing approximately 0.2 to 30% of the binder weight, and 
the polymeric binder is a thermoplastic binder representing about 1 to 
about 80% of the total layer coverage. 
Any silicone polymer can be employed in the invention providing it contains 
units of a linear or branched alkyl or aryl siloxane. In a preferred 
embodiment of the invention, the silicone polymer is a copolymer of a 
polyalkylene oxide and a methyl alkylsiloxane. This material is supplied 
commercially by BYK Chemie, USA, as BYK-320.RTM.. Another suitable 
silicone material is a polyoxyalkylene-dimethylsiloxane copolymer, sold as 
BYK-301.RTM.. Other suitable silicone materials include linear or pendant 
polyoxyalkylene-group block copolymers. 
Any partially esterified phosphate ester can be employed in the invention. 
In a preferred embodiment, the partially esterified phosphate ester 
contains one or two substituted or unsubstituted alkyl groups having from 
5 to about 20 carbon atoms such as C.sub.8 H.sub.17 O--CH.sub.2 CH.sub.2 
--, C.sub.6 F.sub.13 OC.sub.2 H.sub.2 --, C.sub.2 H.sub.5 O(CH.sub.2 
CH.sub.2 O).sub.6 --CH.sub.2 CH.sub.2 --, C.sub.12 H.sub.25 --, C.sub.16 
H.sub.33 --, HO(CH.sub.2 CH.sub.2 O).sub.5 --CH.sub.2 CH.sub.2 --, 
##STR1## 
or one or two substituted or unsubstituted aryl groups having from about 6 
to about 20 carbon atoms, such as C.sub.6 H.sub.5 --CH.sub.2 --, C.sub.6 
H.sub.5 --CH.sub.2 O(CH.sub.2 CH.sub.2 O).sub.10 --CH.sub.2 CH.sub.2 --, 
p--C.sub.9 H.sub.19 ----C.sub.6 H.sub.4)--, 2,4(n--CH.sub.3 OCH.sub.2 
CH.sub.2)(C.sub.6 H.sub.3)--, p--C.sub.8 F.sub.17 --(C.sub.6 
H.sub.4)--O(CH.sub.2 CH.sub.2 --O).sub.3 --CH.sub.2 CH.sub.2 --, 
p--CN--(C.sub.6 H.sub.4)--O(CH.sub.2 CH(CH.sub.3)O).sub.2 --CH.sub.2 
CH.sub.2 --; such groups having from 0 to about 30 linking groups such as 
alkylene oxide, sulfonamide, amide, carbonyl, sulfide, sulfone, imide, 
etc. In a highly preferred embodiment, the partially esterified phosphate 
ester contains one of two fluorinated alkyl or aryl groups. An example of 
such a material is the following 
##STR2## 
This material is supplied commercially by duPont as Zonyl UR.RTM. 
Fluorosurfactant. Another suitable partially esterified phosphate ester is 
Gafac RA-600.RTM. (GAF Corp.) which is described as a complex phosphate 
mono- and di-ester of nonionic surfactants of the ethylene-oxide adduct 
type. 
Any polymeric binder can be used in the slipping layer of the invention 
provided it has the desired effect. In a preferred embodiment of the 
invention, thermoplastic binders are employed. Examples of such materials 
include, for example, poly(styrene-co-acrylonitrile) (70/30 wt. ratio); 
poly(vinyl alcohol-co-butyral) (available commercially as Butvar 76.RTM. 
by Dow Chemical Co.; poly(vinyl alcohol-co-acetal); poly(vinyl 
alcohol-co-benzal); polystyrene; poly(vinyl acetate); cellulose acetate 
butyrate; cellulose acetate; ethyl cellulose; bisphenol-A polycarbonate 
resins; cellulose triacetate; poly(methylmethacrylate); copolymers of 
methyl methacrylate; poly(styrene-co-butadiene); and a lightly branched 
ether modified poly(cyclohexylene-cyclohexanedicarboxylate): 
##STR3## 
In a preferred embodiment of the invention, the thermoplastic binder is a 
styrene-acrylonitrile copolymer. 
The amount of polymeric binder used in the slipping layer of the invention 
is not critical. In general the polymeric binder may be present in an 
amount of from about 0.1 to about 2 g/m.sup.2, representing from about 1 
to about 80% of the total layer coverage. 
Any dye can be used in the dye layer of the dye-donor element of the 
invention provided it is transferable to the dye-receiving layer by the 
action of heat. Especially good results have been obtained with sublimable 
dyes. Examples of sublimable dyes include anthraquinone dyes, e.g., 
Sumikalon Violet RS.RTM. (product of Sumitomo Chemical Co., Ltd.), Dianix 
Fast Violet 3R-FS.RTM. (product of Mitsubishi Chemical Industries, Ltd.), 
and Kayalon Polyol Brilliant Blue N-BGM.RTM. and KST Black 146.RTM. 
(products of Nippon Kayaku Co., Ltd.); azo dyes such as Kayalon Polyol 
Brilliant Blue BM.RTM., Kayalon Polyol Dark Blue 2BM.RTM., and KST Black 
KR.RTM. (products of Nippon Kayaku Co., Ltd.), Sumickaron Diazo Black 
5G.RTM. (product of Sumitomo Chemical Co., Ltd.), and Miktazol Black 
5GH.RTM. (product of Mitsui Toatsu Chemicals, Inc.); direct dyes such as 
Direct Dark Green B.RTM. (product of Mitsubishi Chemical Industries, Ltd.) 
and Direct Brown M.RTM. and Direct Fast Black D.RTM. (products of Nippoin 
Kayaku Co. Ltd.); acid dyes such as Kayanol Milling Cyanine 5R.RTM. 
(product of Nippon Kayaku Co. Ltd.); basic dyes such as Sumicacryl Blue 
6G.RTM. (product of Sumitomo Chemical Co., Ltd.), and Aizen Malachite 
Green.RTM. (product of Hodogaya Chemical Co., Ltd.); 
##STR4## 
or any of the dyes disclosed in U.S. Pat. No. 4,541,830, the disclosure of 
which is hereby incorporated by reference. The above dyes may be employed 
singly or in combination to obtain a monochrome. The dyes may be used at a 
coverage of from about 0.05 to about 1 g/m.sup.2 and are preferably 
hydrophobic. 
The dye in the dye-donor element is dispersed in a polymeric binder such as 
a cellulose derivative, e.g., cellulose acetate hydrogen phthalate, 
cellulose acetate, cellulose acetate propionate, cellulose acetate 
butyrate, cellulose triacetate; a polycarbonate; 
poly(styrene-co-acrylonitrile), a poly(sulfone) of a poly(phenylene 
oxide). The binder may be used at a coverage of from about 0.1 to about 5 
g/m.sup.2. 
The dye layer of the dye-donor element may be coated on the support or 
printed thereon by a printing technique such as a gravure process. 
Any material can be used as the support for the dye-donor element of the 
invention provided it is dimensionally stable and can withstand the heat 
of the thermal printing heads. Such materials include polyesters such as 
poly(ethylene terephthalate); polyamides; polycarbonates; glassine paper; 
condenser paper; cellulose esters such as cellulose acetate; fluorine 
polymers such as polyvinylidene fluoride or 
poly(tetrafluoroethylene-co-hexafluoropropylene); polyethers such a 
polyoxymethylene; polyacetals; polyolefins such as polystyrene, 
polyethylene, polypropylene or methylpentane polymers; and polyimides such 
as polyimide-amides and polyether imides. The support generally has a 
thickness of from about 2 to about 30 .mu.m. It may also be coated with a 
subbing layer, if desired. 
The dye-receiving element that is used with the dye-donor element of the 
invention usually comprises a support having thereon a dye image-receiving 
layer. The support may be a transparent film such as a poly(ether 
sulfone), a polyimide, a cellulose ester such as cellulose acetate, a 
poly(vinyl alcohol-co-acetal) or a poly(ethylene terephthalate). The 
support for the dye-receiving element may also be reflective such as 
baryta-coated paper, polyethylene-coated paper, white polyester (polyester 
with white pigment incorporated therein), an ivory paper, a condenser 
paper or a synthetic paper such as duPont Tyvek.RTM.. In a preferred 
embodiment, polyester with a white pigment incorporated therein is 
employed. 
The dye image-receiving layer may comprise, for example, a polycarbonate, a 
polyurethane, a polyester, polyvinyl chloride, 
poly(styrene-co-acrylonitrile), poly(caprolactone) or mixtures thereof. 
The dye image-receiving layer may be present in any amount which is 
effective for the intended purpose. In general, good results have been 
obtained at a concentration of from about 1 to about 5 g/m.sup.2. 
As noted above, the dye-donor elements of the invention are used to form a 
dye transfer image. Such a process comprises imagewise-heating a dye-donor 
element as described above and transferring a dye image to a dye-receiving 
element to form the dye transfer image. 
The dye-donor element of the invention may be used in sheet form or in a 
continuous roll or ribbon. If a continuous roll or ribbon is employed,it 
may have only one dye thereon or may have alternating areas of different 
dyes, such as sublimable cyan, magenta, yellow, black, etc., as described 
in U.S. Pat. No. 4,541,830. Thus, one-, two- three- or four-color elements 
(or higher numbers also) are included within the scope of the invention. 
In a preferred embodiment of the invention, the dye-donor element comprises 
a poly(ethylene terephthalate) support coated with sequential repeating 
areas of cyan, magenta and yellow dye, and the above process steps are 
sequentially performed for each color to obtain a three-color dye transfer 
image. Of course, when the process is only performed for a single color, 
then a monochrome dye transfer image is obtained. 
Thermal printing heads which can be used to transfer dye from the dye-donor 
elements of the invention are available commercially. There can be 
employed, for example, a Fujitsu Thermal Head (FTP-040 MCS001), a TDK 
Thermal Head F415 HH7-1089 or a Rohm Thermal Head KE 2008-F3. 
A thermal dye transfer assemblage of the invention comprises 
(a) a dye-donor element as described above, and 
(b) a dye-receiving element as described above, 
the dye-receiving element being in a superposed relationship with the 
dye-donor element so that the dye layer of the donor element is in contact 
with the dye image-receiving layer of the receiving element. 
The above assemblage comprising these two elements may be preassembled as 
an integral unit when a monochrome image is to be obtained. This may be 
done by temporarily adhering the two elements together at their margins. 
After transfer, the dye-receiving element is then peeled apart to reveal 
the dye transfer image. 
When a three-color image is to be obtained, the above assemblage is formed 
on three occasions during the time when heat is applied by the thermal 
printing head. After the first dye is transferred, the elements are peeled 
apart. A second dye-donor element (or another area of the donor element 
with a different dye area) is then brought in register with the 
dye-receiving element and the process repeated. The third color is 
obtained in the same manner. 
The following example is provided to illustrate the invention.

EXAMPLE 1 
A dye-receiving element was prepared by coating 2.9 g/m.sup.2 of Makrolon 
5705.RTM. polycarbonate resin (Bayer A. G.), 
1,4-didecoxy-2,5-dimethoxybenzene (0.32 g/m.sup.2) and FC-431.RTM. (3M 
Corp.) surfactant (0.016 g/m.sup.2) using a solvent mixture of methylene 
chloride and trichloroethylene on a titanium dioxide-containing 175 .mu.m 
poly(ethylene terephthalate) support. 
A cyan dye-donor element was prepared by coating on a 6 .mu.m poly(ethylene 
terephthalate) support a dye layer containing the following cyan dye (0.28 
g/m.sup.2), duPont DLX-6000 Teflon.RTM. micropowder (0.016 g/m.sup.2), and 
FC-431.RTM.(3M Corp.) surfactant (0.009 g/m.sup.2) in a cellulose acetate 
butyrate (14% acetyl, 38% butyryl) binder (0.50 g/m.sup.2) coated from a 
toluene/methanol solvent mixture. 
Cyan dye: 
##STR5## 
On the back side of the dye-donor, a subbing layer as described in 
Application Ser. No. 923,443, of Harrison, Kan and Vanier, filed Oct. 27, 
1986, entitled "Polyester Subbing Layer for Slipping Layer of Dye-Donor 
Element Used in Thermal Dye Transfer" was coated followed by various 
slipping layers coated from solvent mixtures of propyl acetate, butanone, 
butyl acetate and methanol as follows: 
Control 1--Support only. No layer. 
Control 2--Binder only of poly(styrene-co-acrylonitrile) (70:30 wt. ratio) 
(0.54 g/m.sup.2). 
Control 3--Binder and silicone material: poly(styrene-co-acrylonitrile) 
(70:30 wt. ratio) (0.54 g/m.sup.2) and BYK-320 silicone (0.0054 
g/m.sup.2). 
Control 4--Binder and phosphate ester: poly(styrene-co-acrylonitrile) 
(70:30 wt. ratio) (0.54 g/m.sup.2) and Zonyl UR phosphate ester (0.054 
g/m.sup.2). 
Control 5--Binder and phosphate ester at lower concentration: 
poly(styrene-co-acrylonitrile) (70:30 wt. ratio) (0.54 g/m.sup.2) and 
Zonyl UR phosphate ester (0.022 g/m.sup.2). 
Control 6--Neutralized phosphate ester with surfactant: Neutralized Zonyl 
UR phosphate ester (0.054 g/m.sup.2) and Aerosol OT (an anionic surfactant 
from American Cyanamid) (0.0027 g/m.sup.2) coated without binder from a 
methanol/water solvent. 
Slipping Layer 1 of Invention--Binder, silicone material and phosphate 
ester: poly(styrene-co-acrylonitrile) (70:30 wt. ratio) (0.54 g/m.sup.2), 
BYK-320 silicone (0.011 g/m.sup.2) and Zonyl UR phosphate ester (0.054 
g/m.sup.2). 
Slipping Layer 2 of Invention--Binder, silicone material and phosphate 
ester at lower concentration: poly(styrene-co-acrylonitrile) (70:30 wt. 
ratio) (0.54 g/m.sup.2), BYK-320 silicone (0.0054 g/m.sup.2) and Zonyl UR 
phosphate ester (0.022 g/m.sup.2). 
The dye side of each dye-donor element strip 1.25 inches (32 mm) wide was 
placed in contact with the dye image-receiving layer of the dye-receiver 
element of the same width. The assemblage was fastened in the jaws of a 
stepper motor driven pulling device. The assemblage was laid on top of a 
0.55 inch (14 mm) diameter rubber roller and a TDK Thermal Head (No. 
L-133) was pressed with a force of 8.0 pounds (3.6 kg) against the 
dye-donor element side of the assemblage pushing it against the rubber 
roller. 
The imaging electronics were activated causing the pulling device to draw 
the assemblage between the printing head and roller at 0.123 inches/sec 
(3.1 mm/sec). Coincidentally, the resistive elements in the thermal print 
head were pulse-heated from 0 up to 8.3 msec to generate an "area test 
pattern" of given density. The voltage supplied to the print head was 
approximately 22 v representing approximately 1.6 watts/dot (13 
mjoules/dot) for maximum power to the 0.1 mm.sup.2 area pixel. 
As each `area test pattern` of the given density was being generated, the 
force required for the pulling-device to draw the assemblage between the 
print-head and roller was measured using a Himmelstein Corp. 10010 Strain 
Gauge (10 lb. range) and 6-205 Conditioning Module. 
The following results were obtained at various steps of the test pattern: 
TABLE 1 
______________________________________ 
Relative Force (lbs) 
Step 0 Step 8 
Slipping 
(D-min) Step 2 Step 4 (D-max) 
Layer (D .about.0.08) 
(D .about.0.3) 
(D .about.1.1) 
(D .about.2.4) 
______________________________________ 
Control 1 
4.6 7.2 Tore Tore 
Control 2 
&gt;8.4 &gt;8.4 &gt;8.4 7.5 
Control 3 
6.0 7.3 5.1 4.8 
Control 4 
5.2 4.7 4.3 4.1 
Control 5 
5.7 5.4 4.6 4.2 
Control 6 
5.6 5.2 5.2 5.2 
Invention 1 
4.4 4.3 4.2 3.9 
Invention 2 
5.5 5.1 4.3 4.0 
______________________________________ 
The above data shows that the slipping layer composition of the invention 
minimizes the force required for passage through the thermal head in 
comparison to various control materials. In particular, when both the 
silicone polymer and the phosphate ester in the same amounts as the 
controls were added to the binder, the relative force went down to an 
amount which is better than the result obtained with either material 
alone. 
EXAMPLE 2 
A dye-receiving element was prepared as in Example 1. 
A cyan dye-donor element was prepared by coating on a 6 .mu.m poly(ethylene 
terephthalate) support a dye layer containing the same cyan dye as in 
Example 1 (0.28 g/m.sup.2) and duPont DLX-6000 Teflon.RTM. micropowder 
(0.016 g/m.sup.2) in a cellulose acetate propionate (2.5% acetyl, 45% 
propionyl) binder (0.44 g/m.sup.2) coated from a toluene, methanol and 
cyclopentanone solvent mixture. 
On the back side of the dye-donor, a subbing layer as described in 
Application Ser. No. 923,443, of Harrison, Kan and Vanier, filed Oct. 27, 
1986, entitled "Polyester Subbing Layer for Slipping Layer of Dye-Donor 
Element Used in Thermal Dye Transfer" was coated. On top of this subbing 
layer, various slipping layers of a phosphate ester and a silicone 
component were coated in a poly(styrene-co-acrylonitrile) binder (70:30 
wt. ratio) (0.54 g/m.sup.2) from either a toluene and 3-pentanone or 
toluene and methanol solvent mixture. 
The phosphate esters used were duPont Zonyl UR.RTM. Fluorosurfactant, 
described above, and Gafac RA-600.RTM. (GAF Corp.), described above. The 
silicone used was BYK-320.RTM. (BYK-Chemie USA), described above. 
The elements were processed as in Example 1 to give the following results: 
TABLE 2 
______________________________________ 
Phosphate Relative force (lbs) 
Ester Silicone Step 2 
(g/m.sup.2) (g/m.sup.2) 
(D .about.0.3) 
______________________________________ 
Controls 
Zonyl (0) 0.011 3.7 
Zonyl (0) 0.032 2.5 
Zonyl (0.011) 0 2.7 
Zonyl (0.032) 0 2.0 
Invention 
Zonyl (0.011) 0.011 1.4 
Zonyl (0.032) 0.032 1.4 
Controls 
Gafac (0) 0.011 3.2 
Gafac (0) 0.032 3.3 
Gafac (0.011) 0 3.0 
Gafac (0.032) 0 1.5 
Invention 
Gafac (0.011) 0.011 1.3 
Gafac (0.032) 0.032 1.4 
______________________________________ 
The above data show that use of the phosphate ester component or the 
silicone component alone requires much greater force for passage through 
the thermal head than use of a lower total quantity of the combined 
components. When either phosphate ester was used in combination with the 
silicone, equally good results were obtained at low or high coverages. 
EXAMPLE 3 
Different Binders 
A dye-receiver was prepared as in Example 1. Dye-donors were prepared as in 
Example 2 except that on top of the subbing layer, various slipping layers 
of Gafac RA-320.RTM. phosphate ester and BYK-320.RTM. silicone were coated 
at the indicated level in either a poly(methylmethacrylate) or General 
Electric Lexan 141.RTM. bisphenol-A polycarbonate binder (0.54 g/m.sup.2) 
from a toluene and 3-pentanone solvent mixture. 
The elements were processed as in Example 1 to give the following results: 
TABLE 3 
______________________________________ 
Poly(methylmethacrylate) Binder 
Phosphate Relative force (lbs) 
Ester Silicone Step 2 
(g/m.sup.2) (g/m.sup.2) 
(D .about.0.3) 
______________________________________ 
Controls 
(0) 0 4.5 
(0) 0.022 2.5 
(0.022) 0 4.4 
Invention 
(0.011) 0.011 1.8 
(0.022) 0.022 1.6 
______________________________________ 
TABLE 4 
______________________________________ 
Bisphenol-A Polycarbonate Binder 
Phosphate Relative force (lbs) 
Ester Silicone Step 2 
(g/m.sup.2) (g/m.sup.2) 
(D .about.0.3) 
______________________________________ 
Controls 
(0) 0 4.7 
(0) 0.022 2.2 
(0.022) 0 2.3 
Invention 
(0.011) 0.011 2.1 
(0.022) 0.022 1.8 
______________________________________ 
The above data show that irrespective of the binder used, combinations of a 
partial phosphate ester and silicone polymer effectively reduce the force 
for passage through the thermal head. 
The invention has been described in detail with particular reference to 
preferred embodiments thereof, but it will be understood that variations 
and modifications can be effected within the spirit and scope of the 
invention.