Conditional Limitations In Control System Claims

Most control systems utilize something akin to if-then software logic. This typically involves determining if a condition is met, and then taking some action depending on whether the condition is met or not met. Such logic is often at the heart of an invention.

A recent trend at the USPTO is to treat claims having if-then type features as "conditional" elements. I.e., optional elements that can be read out of the claims. Of course, this makes rejecting the claims easy since the Examiner no longer needs to actually find the claimed elements in the state of the art. This trend obviously follows the precendential PTAB decision of in re Schulhauser.

Two recent PTAB decisions illustrate that whether or not limitations are required is not always so easy to identify. 

A first example, 11/455,442, relates to a navigation system operating method for collecting traffic information:

A method of collecting traffic information, comprising: ...
determining, by the navigation system, that a position of the vehicle has changed and subsequently determining whether the location reference code which represents that portion of the road network upon which the vehicle is located has changed;
when the location reference code has not changed, obtaining a second vehicle speed representative of the speed of the vehicle, and
when the location reference code has changed, determining, by the navigation system, an average vehicle speed of the vehicle on the portion of the road network represented by the previous location reference code by averaging the first and second vehicle speeds of that vehicle, and transmitting, by the navigation system, data that indicates the previous location reference code and the average vehicle speed from the vehicle to a central traffic facility.

Here, the claim explicitly requires determining a condition, and then taking a first action when the condition is not met, and taking a second action when the condition is met. Nevertheless, the Board found the limitations conditional:

Contrast this with another decision issued by the PTAB where similar claim language was interpreted to require the limitations.  In 12/121,832, the invention related to a method for vehicle heating.

A method of operating a heating system in a vehicle, the method comprising the steps of:

(a) determining if a power plant is operating;

(b) determining if a temperature of a coolant in a power plant coolant loop is above a predetermined temperature threshold;

(c) when the temperature in the power plant coolant loop is not above the predetermined temperature threshold and the power plant is operating, actuating a valve to isolate a heater core coolant loop from the power plant coolant loop, activating a coolant pump in the heater core coolant loop and activating a coolant heater in the heater core coolant loop to heat the coolant in the heater core coolant loop before the coolant flows through a heater core in a first direction, and

(d) actuating the valve to direct the coolant from the heater core coolant loop into the power plant coolant loop and the coolant from the power plant coolant loop into the heater core coolant loop and through the heater core in the first direction when the temperature in the power plant coolant loop is at or above the predetermined temperature threshold.

Here, the Examiner addressed the issue under Section 112, arguing that the claim was unclear because one can infringe the claim by performing only step (a) because the remaining steps do not apply if the power plant is not operating.

The PTAB found otherwise:

So, while the PTAB does not directly find that all of the claimed elements (a)-(d) are required, the rest of the decision goes on to analyze the cited references and find that they do not disclose limitation (d), implying that said limitation must be considered when analyzing the claims. Interestingly, ALJ Horner wrote the decision in Schulhauser as well as in this case where the rejection was reversed!

Because it is not exactly clear how the PTAB will decide these cases, nor how Examiners will examine such claims in the years to come, various strategies might be included when drafting an application. For example, one might combine the mutually exclusive actions into a single step - although it is unclear if this really would make a difference. Another option is to include system claims with instructions stored in memory, as these structural elements should not be considered optional in the same sense as the reasoning in Schulhauser. Still another option includes writing claim actions that must occur "during" or "while" certain conditions, as these should not be considered conditional on those conditions occurring. Even another option might include claiming a method that transitions from one state to the other based on the condition being met or not. Clearly there must be a way for a method to claim the if-then operations, since Schulhauser makes clear that the problem was the claims "as written" under the BRI.