ROBERT E. MALM, Ph.D

ATTORNEY AT LAW

 

CLAIMCRAFTED™ PATENT APPLICATIONS

 For Want of a Nail
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For Want of a Nail

The legal specification of an invention is provided by "claims" which particularly point out and distinctly claim the subject mater which the inventor regards as his invention.

An invention typically can take on many different forms called "embodiments." Quality claims are those written to include all possible embodiments of the invention except those disclosed in the prior art. Any embodiments excluded by the claims are the equivalent of free licenses to the public to practice the unclaimed embodiments of the invention.

Patent attorneys do not consciously avoid writing quality claims. They simply lack the ability or are compelled by their circumstances not to expend the time and effort required to write quality claims. Patent attorneys are usually not equipped by training or experience to envision the conceptual basis of an invention. A bachelor's degree in engineering, by itself, does not provide a patent attorney with the conceptual capabilities required to write quality claims. To illustrate the point, I describe below fictionally-embellished events from the past.

An inventor visited a patent attorney and described his invention. It was a device for measuring the angular rate of change of the orientation of a vehicle. The inventor described two embodiments of the invention and the patent attorney, in writing the specification for a patent application, produced the following two claims:

1. A turn indicator for vehicles comprising a weighted leaf spring elastically clamped at one end, so that it is forced to turn with the vehicle about an axis parallel to the spring but is free at its weighted end to vibrate at its natural period about a transverse axis, . . . and means for detecting and measuring the amplitude and phase of said torsional vibration [about the axis parallel to the spring] as an indication of the rate and direction of turn of the vehicle.

2. A rate of turn indicator comprising a base subject to being turned, a tuned fork having two tines elastically coupled to said base adjacent the junction of said tines, means for vibrating said tines periodically and rapidly so as to vary the space between the free ends of the same, and means responsive to variations in the twist between the junction of said tines and said base for detecting rotation of said base.

The inventor, in reviewing these claims, was quite satisfied. The patent attorney had claimed the invention exactly as the inventor had described it to him. What more could the patent attorney have done?

The inventor's patent attorney was a cut above the typical patent attorney. He consulted with the inventor and concluded that claim 1 could be written in somewhat broader terms as follows:

1A. A turn indicator for indicating orientation about an axis comprising a base which orients about such axis, a movable mass elastically coupled to said base with sufficient stiffness to force orientation of said mass with said base, but with sufficient resilience to permit a natural torsional period of oscillation, the elasticity of said mass also permitting free vibration alternately toward and away from said orientation axis of the same at a natural frequency the same as that of said torsional oscillation, and means for detecting and measuring the amplitude of the torsional oscillation about said axis for indicating the rate of orientation.

The patent attorney has replaced "weighted leaf spring" by "a moveable mass elastically coupled to said base". This appears to be a step in the right direction in that "a moveable mass elastically coupled to said base" is a more encompassing term than "weighted leaf spring".

The patent attorney also concluded that claim 2 could be written in broader terms by following the claim-1A pattern:

2A. Apparatus responsive to changes of orientation comprising a base, a plurality of movable masses normally positioned symmetrically about an axis therebetween, motive means for alternately drawing said masses toward said axis and repelling them from said axis, elastic torsional constraining means connecting said masses to said base, and means responsive to variations of orientation of said masses and said base about said axis for detecting rotation of said base about said axis.

Here, the patent attorney has made several steps in the right direction by replacing "tuned fork" by "plurality of movable masses". The use of "plurality of" rather than "two" covers a broader spectrum of devices.

The question at this point is whether the patent attorney really accomplished much (beyond extending the claim coverage from one or two masses to a plurality) by adding claims 1A and 2A to the specification.

Is a leaf spring the only embodiment of a movable mass elastically coupled to said base with sufficient stiffness to force orientation of said mass with said base, but with sufficient resilience to permit a natural torsional period of oscillation, the elasticity of said mass also permitting free vibration alternately toward and away from said orientation axis of the same?

It would appear that any elastically-deflectable elongated member, regardless of cross-sectional shape, would fall within the claim language. However, it is possible that an embodiment wherein masses are coupled by coil springs to a rigid rod which in turn is attached to the base would not be included under claims 1A and 2A. The patent attorney could have significantly broadened the claim coverage by substituting "elastically constrained to a point in a fixed position relative to said base" for "elastically coupled to said base".

Let us not dwell, however, on such minor incremental advancements toward a set of quality claims. Let us continue with our fictionalized account of how claims are prepared by the typical patent attorney.

In his initial meeting with the patent attorney, the inventor described two embodiments of his invention as follows:

A leaf spring clamped at one end, and preferably weighted at the other, so that it is forced to turn with the body about the major axis of the spring or an axis parallel thereto, but may vibrate like one tine of a tuning fork across said axis.

Two leaf springs clamped together and vibrating in opposition (i.e. a tuning fork).

It is apparent from claims 1 and 2 above that the patent attorney simply claimed the inventor's embodiments. And this was a good starting point. Claims for the embodiments of an inventor's invention are important components of a set of quality claims. But they are not the end-all that typical patent attorneys consider them to be.

After determining how the embodiments of an invention works, a patent attorney interested in writing a set of quality claims should seek to determine the basic principles of operation of the invention.

The inventor of the tuning-fork gyro was very helpful in this regard. He identified the principles of operation with the following words:

Upon rotation of the base, the mass is constrained by its elastic connection to rotate along with the base, but its inertia compels it to lag slightly behind the base in rotation about the selected axis, by an average angle of displacement substantially proportional to the angular acceleration of the base. Moreover, since the moment of inertia of the mass about the selected axis is alternately increasing and decreasing periodically, the relative angular displacement between the base and the mass varies periodically and synchronously with the variation of the moment of inertia of the mass. The amplitude of the periodic variation of angular displacement between the mass and the base is substantially proportional to the rate of change of orientation of the base about the selected axis, i.e., substantially proportional to the angular velocity of the base.

Readers—raise your hands if you now understand the principles of operation of the tuning-fork gyro.

Those of you who did not raise your hands would probably be joined by most patent attorneys. And most patent attorneys, not understanding the principles of operation of the tuning-fork gyro, would throw up their hands and be content with just claims 1A and 2A.

The patent attorney preparing the tuning-fork gyro patent application was provided some additional helpful information by the inventor who said:

It is not necessary for the purpose of the present invention that a tuning fork be employed as the device for periodic variation of moment of inertia. Any suitable arrangement for periodically varying the moment of inertia of a mass may be employed for this purpose.

The patent attorney did not include a claim for "any suitable arrangement" highlighted above, and one might wonder why he did not. It would have been such a magnificently-broad claim for the invention.

The answer is that the inventor, in reviewing this all-encompassing claim, informed the patent attorney that the claim would appear to include the "wineglass" resonator that is the ancestor of the hemispherical resonator gyro. The angular rotation sensing capabilities of a vibrating wineglass was a discovery of G. H. Bryan who published his findings in 1890.

The problem faced by the patent attorney at this point was how to write a claim like the "any suitable arrangement" claim but which excluded the "wineglass" resonator. Not knowing much about the equations of motion for a solid body and the role played by the moment of inertia, the patent attorney found the solution of the problem beyond his capabilities. He contented himself with the claims he had already written for the inventor's species.

The situation just described is not unusual where the subject matter of the invention has deep roots in science or technology. If the patent attorney is incapable of understanding the principles of operation of the invention, it is unlikely that he will be able to write quality claims.

Some years after our inventor received a patent for his leaf-spring species, a second inventor obtained a patent for another species of the first inventor's invention. The second inventor described the structure of his invention as follows:

A pair of cantilevered piezo-electric crystals 28 and 30 are radially oppositely positioned and attached to structural member 26. Crystals 28 and 30 are adapted to support probes 32 and 34 respectively.

The second inventor described the operation of his invention as follows:

Any rotation of housing16 about an axis normal to the axis of shaft 22 causes fluid 36 to shift in rotating chamber means 10 to cause probes 32 and 34 to be deflected upward or downward in accordance with the instantaneous position of probes 32 and 34 relative to the axis of rotation of the applied angular velocity. As probes 32 and 34 turn about the axis of shaft 22 they are deflected in a substantially sinusoidal deflection pattern thereby to flex crystals 28 and 30 to generate an electrical voltage which is a sinusoidal voltage, the phase of which is a measure of the position of the axis of applied angular velocity normal to shaft 22, and the amplitude of which is a measure of the amplitude of applied angular velocity about an axis normal to the axis of shaft 22.

The second inventor mounted two of the first inventor's leaf springs in opposition on a shaft and caused the leaf springs to rotate about an axis rather than to vibrate back and forth.

One sees by this example the potential value of having a patent with quality claims. The second inventor's invention at first glance seems quite different from the first inventor's. And yet both inventions operate in accordance with the same scientific principles. The first inventor had the opportunity of participating in the revenue stream from the second inventor's invention but was unable to capitalize on his opportunity because his patent did not include a set of quality claims.

In order to show the ideal outcome of the above-described situation, we assume the patent attorney responsible for preparing the first inventor's patent application becomes indisposed and a technically-expert patent attorney (TEPA) takes over the case. TEPA does a bit of research and discovers that another way of describing the operation of the first inventor's invention is:

An arrangement of one or more discrete masses wherein each mass moves cyclically in one direction at one time and in the opposite direction at another time, the angular velocity of the arrangement being determined by measuring the coriolis accelerations of the one or more masses.

Note that the first inventor's vibrating leaf springs and the second inventor's rotating leaf springs both can be characterized as an arrangement of one or more discrete masses wherein each mass moves cyclically in one direction at one time and in the opposite direction at another time.

TEPA writes a claim based on the forgoing and lo and behold, achieves a "genus" claim. The "genus" claim reads on both the first inventor's species and the second inventor's "species" and yet does not read on the "wineglass" species.

 

© 2002 Robert Malm