Back in 2007, Fenner Investment Ltd. sued Microsoft, Nintendo and Sony for infringement of U.S. Patent No. 6,297,751, relating to low voltage joystick port interfaces. Claim 1 is reproduced below:


1. An interface between a joystick device having a first source voltage and
a processor, comprising:
a Resistor-Capacitor (RC) network, connected to the joystick device, said
RC network having a capacitor that generates an analog joystick position
measurement signal; and
an interface circuit having a second source voltage that is lower than the
first source voltage, including
a buffer circuit, in a first operation mode of said interface, receiving
said analog joystick position measurement signal, outputting a first logic state
as a digital signal before said analog joystick measurement signal exceeds said
predetermined threshold, and outputting a second logic state as said digital
signal after said analog joystick measurement signal exceeds said predetermined
threshold; and
a pulse generator generating a pulse based on said digital signal in said
first operation mode of said interface, a width of said pulse representing a
coordinate position of said joystick device, the capacitance value of said
capacitor being a function of said predetermined threshold that prevents
deviation of the width of said pulse from expected values.

In 2009, the U.S. District Court in the Eastern District of Texas held in favor of the defendants, finding that summary judgment was appropriate with respect to both the issue of direct infringement and and the issue of the doctrine of equivalents. A summary of the issues and the District Court’s decision can be found here.

Subsequently and as noted here, Fenner Investments filed a notice of appeal in the U.S. District Court for the Eastern District of Texas on July 15, 2009. Specifically, Fenner appealed the final order granting summary judgment of noninfringement to Microsoft and Nintendo made in March 2009 and an August 2008 opinion interpreting the patent claim language at issue in the case.

Unfortunately for Fenner Investments (and fortunately for the defendants), the Federal Circuit issued its opinion on March 15, 2010, upholding the District Court’s decision. In addition to affirming the District Court’s findings, the opinion also indicates that the Federal Circuit does not address Fenner Investments’ arguments with respect to the construction of the term “processor.” The opinion does not provide an explanation as to why Fenner Investments’ arguments were not addressed by the court. The opinion can be found here.

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