Mitros:Homework 3 (2/4/2011)

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Relevant Patents

Glencoe/Rolf patent 2739518 (Issued in 1956, however, the device was marketed in May 1951, before Graham's '798 patent was filed)

Graham '811


Argument for Obviousness

In analyzing patent '798, it has been determined that the patent is invalid in light of the content of the previous art (as will be shown by both the '811 Graham patent and the Glencoe device) as well as the level of skill required to devise the item contained in patent '798 is not beyond that of an ordinary mechanic skilled in the art. Therefore, by section 103 the patent falls under the category of obvious as has been established through the precedent of the court and should be found invalid.

In order to establish the nature of the previous art, both the Glencoe mechanism and patent '811 were taken into consideration. Patent '811 claims to contain "a plow structure wherein the pumping action of the ground working tools enhance the desirable features of the plow and...improved mounting [that] reduces or eliminates the breakage of the ground working devices since they yield automatically under action of the springs when they strike immovable objects such as rocks or other destructions." Patent '798 claims mostly the same functioning except with a "simple and efficient manner and without producing destructive strains on the plow frame or excessive wear on the mounting parts." When comparing the structures of the two items contained within the patents the two mechanisms are very similar in nature. Both achieve the same general motion of allowing the shank to rise over solid objects in the ground by attaching the shank to a spring and hinge system rigidly attached to a plow. There are two noticable differences between the two different systems. In '811, the shank is sandwiched between the fixed upper plate of the hinge and the lower plate which rotates relative to the top plate on a revolute joint. When a force is applied on the end of the shank, the part of the shank that rests in between the hinge pushes down on the lower plate, compressing the spring and rod device. When the force is no longer applied, the stored potential energy of the spring pulls both the lower plate and the shank back to its initial position. The shank is in not rigidly attached to the lower hinge and is preventing from sliding by the rod and spring system that passes through the hinge and shank. In the '798 patent the shank is attached beneath the lower plate of the hinge. This is done by using a stirrup towards the back of the plate and bolting the front end of the shank and plate together. This different mounting prevents the "excessive wear on mounting parts" mentioned earlier. In patent '811, when the shank and lower plate were forces to rotate down, the shank had to use the rear edge of the upper plate as a fulcrum point to engage and push the lower hinge down. Over time this would wear out the upper plate. By attaching the shank to the bottom of the lower plate, this engagement with the upper plate was eliminated and the subsequent wear that was caused by it. However, this is not something that would be outside the skills of an ordinary mechanic in the art. Both patents require that one of the hinge plates be rigidly attached to the plow in order for the system to allow the proper motion of the shank. This left one of two options for positioning the shank on the moving plate. Either positioning the shank above the moving plate, as was done first in '811, or finding a way to mount it to the bottom of the moving plate, as was later done in '798. A mechanic who was seeking to address the wear out problem would be faced with only one other possible configuration with which to mount the shank to the underside of the hinge. In this configuration, instead of pushing on the hinge, the shank would have to pull on it. This would require that the shank be rigidly attached to the hinge as was done in '798. Since there was only one of two possibilities for mounting the shank in the design, and the essential construction required to either push the lower hinge in the one configuration, or pull the hinge in the other configuration, it can be assumed that an ordinary mechanic skilled in the art would be capable of producing the item contained in '798.

In the Glencoe patent, it claims to contain an invention that "relates to shank holders...which must necessarily be able to rock or pivot at its forward end to permit the implement to yield when exceptionally heavy obstructions are met."

Argument for Nonobviousness