COMMISSIONER'S DECISION
OBVIOUSNESS: Threaded Fastener
The application relates to an improved threaded screw fastener. It was
found that the applicant has made a patentable advance in the art.
Final Action: Reversed - Suggested a claim for allowance.
***********************
This decision deals with a request for review by the Commissioner of
Patents of the Examiner's Final Action dated June 25, 1975, on applica-
tion 149,369 (Class 85-46). The application was filed on August 14,
1972, in the name of Geoffrey Dreger, and is entitled "Thread System."
The Patent Appeal Board conducted a Hearing on March 23, 1977, at which
Mr. D.G. Finlayson represented the applicant. Also in attendance was the
inventor, Mr. G. Dreger.
The application relates to a threaded member capable of being driven into
low density materials. The member has a sharp thread with its leading
angle substantially larger than its trailing angle. The following drawing
from the application shows the threaded member:
(See formula 1)
In the Final Action the examiner refused the application for failing to
define a patentable invention over the following United States patents:
2,350,346 June 6, 1944 Gaskell
2,380,724 July 31, 1945 Crooks
2,742,074 April 17, 1956 Rosan
Claims 1 to 5 were withdrawn. Former claim 6, now claim 1, is the only
claim before us.
The Gaskell patent discloses a threaded member having a thread with a
leading angle of 35ø and a trailing angle of 15ø. Figure 1 of Gaskell,
shown below, illustrates that invention
(See formula 1)
The Crooks patent relates to a wood screw retaining means. The thread
of the screw having a steep pitch of approximately 4 to 8 threads per inch.
That invention is illustrated by Figure 1 of that patent as shown below:
(See formula 2)
The Rosan patent is directed to a removable mounting insert member which is
used in conjunction with a fastening member.
In the Final Action the examiner set forth his position (in part) as follows
(we need only be concerned with the remarks as they apply to former claim 6,
now claim 1):
...
Claim 6 recites in essence the features presented in claims
1-5. Claim 6 is therefore rejected for the same considera-
tions as offered above.
The application is rejected as comprising no patentably novel
subject matter in view of the cited art.
Regarding applicant's response of January 10, 1975 it is held
that
the thread angle 30· - 15· as claimed as against Gaskell's
angle of 35· - 15· is so close that the difference is in-
significant for all practical purposes. Gaskell, moreover,
offers solution to the same type of problem, as stated in column
2, lines 39 ff: "the front face of the thread being inclined
to the vertical at a greater angle than conventional threads
can be driven into the wood with the application of a small
torque, while the rear face of the thread approaching a
buttress thread provides adequate bearing on wood or
similar materials, when tension loads are applied to the
screws and eliminating the possibility of splitting." While the
applicant's explanation is not so specific as that of
Gaskell cited above, it is easy to see that the object is
the same, and there is no significant deviation from the thread
angles.
The self tapping characteristics of applicant's screw are well
known and used in industry, and even if they had been claimed,
they would have contributed nothing to the patentability of
the device. Therefore applicant's argument that "Rosan never
considered a self-tapping screw. This certainly removes Rosan
as an anticipation of broad claim 1" does not apply.
Spacing between the threads has been dealt with in all three
references. Thus Crooks recognizes that "the lesser number
of threads per inch is a great factor in the holding power,
in as much as the fibre of the wood adjacent the shank is cut
or broken at fewer points." Crooks mentions further on
Bakelite, fibre or metal heads to wooden or plastic barrels,
though no specific ratio between thread height and pitch
is given. Gaskell states: "The screw is provided with
threads 4 having a pitch preferably of the order of eight
threads per inch." Rosan specifies the thread pitch as 1.54
to 1.125 of the thread height as compared with applicant's
pitch as being 2.2 to 3 of the thread height. Rosan, confronted
essentially with applicant's problem, increases the height
of the threads, and decreases the thread width, thus in effect
increases the distance between the threads.
Since there is no subject matter in the disclosure that is
unobvious and inventive over the prior art, this application
is refused.
Tn response to that action the applicant presented his views (in part) as
follows:
...
The applicant contends that the Examiner's rejection of the
single claim retained herein is based upon combining details
of several prior art disclosures, one of which Rosan, is not
directed to the subject matter of the two references of
Crooks and Gaskell. Particularly, Rosan directes his device
to a reduced diameter locking ring for an insert and the
insert.
It also appears that despite the availability of the leading
and trailing thread angle of Gaskell and the pitch of Crooks
in the years 1944-45, there is no evidence or suggestion
that these two isolated elements might be combined and some
10-12 years later there is no evidence that the thread depth
of Rosan might be varied to incorporate the thread angles
or the pitch dimension of the two prior art items. The
applicant contends that this is a mosaic on the part of
the Examiner of isolated elements that were patented at widely
spaced intervals of time and that a period of more than ten
years elapsed from the last of the prior art items before
the present invention which is directed to a specific
combination was devised in response to an indicated demand
in a number of industries directly related to the general
subject matter area of the prior art references.
...
The applicant believes that the prima facie view of the Examiner
of non-patentability must be displaced in the present application
to conclude that sufficient is disclosed and claimed to support
a patent in view of the experiments required, the expiry of more
than ten years from the latest of the pertinent prior art refer-
ences and the demonstrated need for the applicant's solution as
supported by the approaches made to the applicant by skilled
artisans in the use of threaded fastener means.
It is the applicant's contention that to deny it protection for
the screw that is exactly and specifically and narrowly defined
in the single claim retained is to contravene the general
principles of a Letters Patent for limited monopoly and is
contrary to all Canadian judicial pronouncements with respect
to the granting of patents for worthwhile novel and utilitarian
developments in response to indicated needs and requirements.
We have considered with care the able and informative arguments presented
at the Hearing by Messrs. Finlayson and Dreger. They attempted to show
that inventive ingenuity was required in developing the instant screw
fastener. We might add that we have no quarrel with the rationale of
the jurisprudence discussed by Mr. Finlayson. The line staff was equally
spirited and firm in its attempt to show a lack of inventive ingenuity.
We have also considered the points raised in the Affidavit by the inventor,
Mr. Dreger, who is as a matter of interest, Vice-President, Research and
Development of the applicant (P. L. Robertson Manufacturing Company,
Limited). Some of the points raised in the affidavit will be commented
on later. The applicant also submitted a further brief and samples of
the screw fasteners to the Board after the date of the Hearing.
The issue to be considered is whether the applicant has made a patentable
advance in the art. We hasten to say that in the present situation such
issue is a difficult one to solve. Claim 1 (former claim 6) reads as follows:
A screw threaded member for use with materials having a
density in the range from about 15 to about 60 pounds
per cubic foot comprising a root portion of predetermined
diameter, a single continuous external sharp-edged thread
portion having a leading angle of 30ø and a trailing
angle of 15ø, the depth of said thread portion being from
30 to 40 percent of the diameter of said root portion,
and the spacing between threads being from 2.2 to 3 times as
great as said thread depth.
The applicant advanced the argument that the examiner was using a mosaic
of patents to deny patentability. We are satisfied, however, that the
cumulative effect of the prior art should be considered when deciding in-
ventiveness (see DeFrees and Better Machine Co. v D.A. Acc. Ltd. 25 Fox P.C.
58 at 59) .
It was made clear at the Hearing that there was indeed a problem to be
solved by the inventor. This is well documented in the affidavit by Mr. Dreger.
The problem was basically one of developing an improved screw fastener for
use in low density materials. The basic question of course is whether or
not the problem was solved in an inventive manner. As a result of this
problem the inventor directed the research to design a screw fastener that
would meet the following criteria:
1. A metal threaded fastener of a type similar to wood
or tapping screws for use with applications using
man-made, low-density materials, replacing such
historically used materials such as wood or plywood.
2. A fastening means per above that can be used in
low-density materials as well as in other
historically used materials.
3. A fastening means not requiring predrilling of holes
in any of the above materials.
4. A fastening means competitive with historically used
fasteners but of superior holding power to same.
5. A fastener that can be produced on present equipment
with modified tooling and at present day speeds.
In considering Rosan it is clear that the treads of the fastener could only
feasibly be cut from a blank and are not normally within the scope of rolling
capabilities. This type of fastener would also require a predrilled hole
before application.
The Gaskell patent does show a threaded fastener where the front face of the
threads is inclined to the vertical at an angle of thirty five degrees while
the rear face of the thread is inclined at an angle of fifteen degrees to the
vertical. This is substantially the same included angle as used by the
applicant. One basic difference is that the applicant continues his thread
to the tip of the screw ending in a sharp point. Gaskell on the other hand
has a blunt end and requires a predrilled hole for application. No predrilled
hole is required for the fastener of the present application.
It is fair to say that Crooks recognized that "the lesser number of threads
per inch is a great factor in the holding power, in as much as the fibre of
the wood adjacent the shank is cut or broken at fewer points." This is of
course only one feature of the present alleged invention. Crooks requires a
predrilled hole however, for application.
At the Hearing it was stated that the instant fasteners greatly resist splitting
and especially when used in the end grain of hardwoods, and without the
necessity and expense of a predrilled hole. This was considered by the
inventor and his industrial informants as an unexpected-plus of the
instant screw fastener. Our attention was also directed to the commercial
success of the instant fastener, with one company alone "purchasing approx-
imately one million LO-ROOT (instant fastener) screws per month." This
may be of interest, but not necessarily conclusive as the requirement of
inventive ingenuity.
At first blush one might consider that the fastener as disclosed is obvious
in view of the prior art. We are not persuaded in the present circumstance
however, that it would be obvious to a skilled artisan in the fastener art
to consider combining the isolated elements of the three prior art patents
to arrive at the design of the instant (LO-ROOT) screw fastener, which can
be manufactured by present day rolling techniques, that do not require any
predrilling of holes, and that can be used in a wide range and variety of
materials. These elements are: the sharp included angle of the asymmetric
thread, the relatively small root diameter, and the distance between the
threads relative to the thread depth. The asymmetric thread is also continued to
the extreme point of the present fastener. It is also of interest to note
that what might be considered as the two basic references were issued to
patents in 1944 and 1945, whereas the filing date of this application is 1972.
The applicant also maintains that "the invention resulted from extensive
experiments and field tests of prototype fastening members which were all
produced within the scope of rolling capabilities and also covered several
angles of threads and spacing of threads."
In our view the examiner capably and fairly set forth his position, and
we agree that the cited art is closely allied to the point in question.
The examiner however, did not have the advantage of some of the points
which were brought out and discussed at great length at the Hearing. In
any event we observe that the applicant cancelled five of the six claims
refused by the examiner after the Final Action. This alone, at least in
part, indicates the correctness of the Final Action. At the onset we
mentioned that the issue before us was a difficult one, partly because the
prior art cited by the examiner was indeed pertinent and generally seemed
to teach the basic features in separate patents, and partly because of the
apparent difficulty in expecting to find a patentable advance in a screw
fastener. We hasten to add however, that without a Hearing a recommendation
to the Commissioner of Patents on this issue would have been much more
difficult.
Having considered all the arguments and points brought to the Board's
attention we are constrained to conclude, but not without some hesitation,
that the applicant has made a patentable advance in the art. We agree with
the applicant that the advance in the art is centered around the sharp
included angle of the asymmetric thread on the shank portion of the self-
drilling and self-tapping fastener. This thread must, of necessity, be
continued to the point thereof, in conjunction with a specified depth of
thread in relation to a set spacing of threads and the diameter of the
screw fastener. In addition we note that the root diameter of the instant
screw fastener is only slightly smaller than the unthreaded shank portion,
thus little if any additional wedging action occurs on a work piece as the
screw advances into a work piece beyond the thread. This characteristic,
we believe, is part of the merit in the present screw fastener being
suitable for use in, for example, the end grain of hardwoods.
Considerable discussion took place at the Hearing as to whether or not claim 1
(previous claim 6) clearly sets forth what the applicant alleged was the
advance in the art. We suggest that it does not, and should be amended to
state that the fastener is self-drilling and self-tapping. More important it
is essential to make it clear that the sharp included angle of the single
continuous asymmetric thread extends along at least a portion of the shank
of the screw member and to the extreme point thereof. This claim should also
refer to the diameter of the shank above the thread as being substantially the
same (or only slightly larger than) the root diameter.
In summary, we are satisfied that the applicant has made a patentable
advance in the art. There is, in our view, sufficient ingenuity that the Com-
missioner ought not to refuse a patent (cf Crosley Radio Corporation v.
Canadian General Electric (1936) S.C.R. 551 at 560).
We recommend therefore that the decision of the examiner in the Final Action
to refuse the claims be affirmed, but that the decision to refuse the
application be withdrawn. We also recommend that claim 1 (former claim 6)
be accepted when amended, as suggested above.
J.F. Hughes
Acting Chairman
Patent Appeal Board, Canada
I have studied the prosecution of this application and have carefully reviewed
the recommendation of the Patent Appeal Board. In the circumstance I have
decided beyond reasonable doubt that the applicant has made a patentable
advance in the art. I withdraw the Final Action as it pertains to the refusal
of the application, and I will accept claim 1 (former claim 6) when amended
along the guidelines set out by the Board. The applicant has six months
within which to submit the proposed amendment, or to appeal this decision
under the provision of Section 44 of the Patent Act.
J.H.A. Gariepy
Commissioner of Patents
Dated at Hull, Quebec
this 27th. day of May, 1977
Agent for Applicant
Meredith & Finlayson
77 Metcalfe St.
Ottawa, Ont.