`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`
`
`RARITAN AMERICAS, INC. D/B/A RARITAN COMPUTER, INC.,
`Petitioner
`
`
`
`v.
`
`
`
`SERVER TECHNOLOGY, INC.,
`Patent Owner
`
`
`
`Case IPR2015-01597
`
`U.S. Patent No. 7,043,543
`Title: Vertical-Mount Electrical Power Distribution Plugstrip
`Filed: August 15, 2001
`Issued: May 9, 2006
`
`
`
`DECLARATION OF DR. MARK HORENSTEIN
`IN SUPPORT OF PETITION FOR INTER PARTES REVIEW OF
`U.S. PATENT NO. 7,043,543
`
`
`
`
`
`
`
`
`
`
`
`
`Raritan v. Server Technology
`
`RARITAN EXHIBIT 1030
`
`
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`
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`
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`DECLARATION OF DR. MARK HORENSTEIN
`
`I, Mark Horenstein, hereby declare as follows:
`
`Petitioner Raritan Americas, Inc. d/b/a Raritan Computer, Inc. has retained
`
`me to provide my opinions in support of their Petition for Inter Partes Review of
`
`U.S. Patent No. 7,043,543. I also provided a declaration in support of their recent
`
`Petition for Inter Partes review of the closely related U.S. Patent No. 7,702,771 on
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`July 15, 2015 (Case IPR2015-01596). I am being compensated for my time at my
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`standard rate of $290 per hour. I have no interest in the outcome of this
`
`proceeding.
`
`I. Background and Qualifications
`
`1.
`
`I am a Professor of Electrical Engineering at Boston University. A
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`copy of my curriculum vitae and list of publications is attached as Exhibit A.
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`2.
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`I have a Bachelor of Science degree from the Massachusetts Institute
`
`of Technology, a Master of Science degree from the University of California at
`
`Berkeley, and a Ph.D. from the Massachusetts Institute of Technology, all in
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`Electrical Engineering.
`
`3.
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`I am currently a tenured professor at Boston University in the
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`Department of Electrical and Computer Engineering. I have been on the faculty of
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`Boston University since 1979, first as an Assistant Professor, then as an Associate
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`Professor, and now as a full Professor. I also served as Associate Chair for
`
`
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`1
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`
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`Undergraduate Programs in the ECE department for a total of twelve years (1990-
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`
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`1998; 2012-2015), and as Associate Dean for Graduate Programs and Research for
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`nine years (1999-2008). I have an active program in teaching and research in areas
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`relevant to power switching technology. I am a Registered Professional Engineer
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`(Electrical) in the Commonwealth of Massachusetts.
`
`4.
`
`Prior to my employment at Boston University, I worked for Spire
`
`Corporation in the areas of high-voltage systems and pulsed power.
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`5.
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`As part of my work at Boston University, I have taught various
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`courses to electrical engineering students over the years. These courses have
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`included, among others, introduction to engineering, electric circuit theory,
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`introductory and advanced electronics, electromagnetics, modern-active circuit
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`design, and power electronics. I was also responsible for developing and teaching
`
`our department’s first Senior Capstone Design course, which I taught for 10 years
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`over the period 1990 to 2000. The course, by my design, continues to be based on
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`a customer model in which the students design a product or system for an outside
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`company or customer.
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`6.
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`A large part of my graduate training involved the study and design of
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`AC power distribution systems. I also have considerable experience in electrical
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`wiring, having served as an apprentice to a Master Electrician during my college
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`years. I have taught both undergraduate and graduate students. Since 1979 and
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`
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`2
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`
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`until the present day, literally thousands of students under my tutelage have
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`
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`graduated from Boston University with Bachelor’s and Master’s degrees in
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`electrical engineering. These students fulfilled their degree requirements in part by
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`taking courses taught by me.
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`7.
`
`As part of my work as a professor at Boston University, I have
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`engaged in various research projects and outside interests. My research projects
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`have included such areas as experimental electromagnetics and electrostatics,
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`electrostatic safety, power-electronics applications, solar energy, and micro-
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`electromechanical systems.
`
`8.
`
`I have authored two books that are used by engineering students:
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`Design Concepts for Engineers, 5th Ed., Upper Saddle River, NJ: Prentice Hall,
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`2015; and Microelectronic Circuits and Devices, 2nd Ed., Upper Saddle River, NJ:
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`Prentice Hall, 1996. I have also authored chapters on industrial applications of
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`electrostatics in two reference books, and I have published numerous journal
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`articles in the field of electrical engineering. In addition, I am named as an
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`inventor on five different patents, all of which are related in various ways to
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`electrical engineering.
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`II. Materials Considered
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`9.
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`In forming my opinions, I have considered my knowledge, my
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`experience, and the following documents, which I understand are exhibits to the
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`3
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`
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`accompanying Petition for Inter Partes Review, as well as the other materials cited
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`
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`herein and/or in the Petition:
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`U.S. Patent No. 7,043,543 to Ewing (Ex. 1001);
`U.S. Patent No. 7,702,771 to Ewing (Ex. 1002);
`U.S. Patent No. 5,949,974 to Ewing (Ex. 1012);
`MasterSwitch VM Power Distribution Unit User Guide, December
`1999 (“MSVM User Guide”) (Ex. 1013);
`MasterSwitch VM Power Distribution Unit Installation and Quick
`Start Manual, December 1999 (“MSVM Quick Start”) (Ex. 1014);
`PowerNet SNMP Management Information Base (MIB) v3.1.0
`Reference Guide, November, 1999 (“MSVM PowerNet Guide”) (Ex.
`1015);
`U.S. Patent No. 6,741,442 to McNally (Ex. 1017);
`Baytech Remote Power Control Unit Owner’s Manual, BayTech
`Manual Publication #U140E125-05, January 2000 (“Baytech
`Manual”) (Ex. 1018);
`Baytech Vertical-Mount Data Center Power Control Press Release,
`October 13, 1999 (“Baytech Press Release”) (Ex. 1019);
`Download of Baytech RPC Series Webpage from web.archive.org,
`capturing webpage as of October 6, 2000 (“Baytech Webpage”) (Ex.
`1020);
`U.S. Patent No. 5,650,771 to Lee (Ex. 1022);
`U.S. Patent No. 6,476,729 to Liu (Ex. 1023);
`U.S. Patent No. 5,595,494 to Wiebe (Ex. 1024);
`U.S. Patent No. 4,853,619 to Paulsen (Ex. 1025);
`Systems Enhancement Corporation PA-800 Manual, October 1, 1996
`(Ex. 1026);
`Systems Enhancement Corporation PA-800 Manual, October 31, 1996
`(Ex. 1027;
`APC Symmetra User’s Manual, rev. October, 1997 (Ex. 1028);
`
`
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`4
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`
`
`•
`•
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`APC PowerStruXure User’s Manual, November 2001 (Ex. 1029); and
`Materials from the prosecution history and reexaminations of STI
`patents and the litigation between STI and APC.
`
`10.
`
`I am also familiar with many of the issues relevant to this IPR
`
`request because of my prior consulting work on behalf of American Power
`
`Conversion Corp. related to the patents of Server Technology, Inc. Specifically,
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`on May 16, 2011, I provided a declaration on behalf APC in an inter partes
`
`reexamination of U.S. Patent No. 7,043,543 (Reexam Control No. 95/001,485). I
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`have also served as an expert witness on behalf of APC in its ongoing litigation
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`with STI involving both the ‘543 and ‘771 patents (District of Nevada, Case No.
`
`06-00698-LRH-VRP). I testified in the jury trial in this litigation on May 21, 2014
`
`and prepared a report, dated May 27, 2011, regarding the invalidity of the ‘543 and
`
`‘771 patents.
`
`III. Level of Ordinary Skill in the Art
`
`11.
`
`In forming my opinions as presented in this declaration, I have
`
`applied the perspective of one of ordinary skill in the art before the time frame of
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`the ‘543 patent. I believe that a person of ordinary skill in the art would have been
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`someone who had a bachelor’s degree in electrical engineering or computer
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`engineering plus approximately one to three years of industrial experience in the
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`field of either intelligent-power distribution devices or electrical-power distribution
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`units (or equivalent). I understand that the time frame of invention that is to be
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`5
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`
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`applied to the ‘543 patent is before August 15, 2001, its filing date. I also
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`
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`understand that the Patent Owner may contend that the time of invention must be
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`before December 8, 2000, the filing date of an earlier STI patent. My opinions do
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`not change if I apply the perspective of one of ordinary skill in the art at this earlier
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`time around the year 2000.
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`12.
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`Furthermore, I believe that my position as a professor who teaches,
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`and has previously taught, students of electrical and computer engineering has
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`given me an excellent understanding of what a person of ordinary skill in the art
`
`would have known before the time of invention.
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`13.
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`In my positions at Boston University, particularly as the Associate
`
`Chair for Undergraduate Programs, I have been actively involved in determining
`
`what courses and concepts should be taught to engineering students. I have also
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`advised these students and taught their courses. A core foundation of our student
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`advising, as well as the mode by which we train students, involves a firm
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`understanding of what electrical and computer engineers must know before
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`entering the engineering profession upon graduation in order to succeed in the
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`workplace. I also have regular conversations with alumni and the directors of our
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`Career Development Office to amplify my understanding of these issues.
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`14.
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`In my role as a professor, I have interacted with many engineering
`
`students, and I have had many opportunities to observe what engineering students
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`6
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`actually know following graduation as they enter the engineering workplace. I had
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`
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`this same understanding before the time frame of the ‘543 patent.
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`15.
`
`As a specific example of both the curriculum choices made to
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`prepare students for jobs as electrical and computer engineers, and my interactions
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`with these students, I note that in 1990, the Department of Electrical and Computer
`
`Engineering at Boston University instituted a required Senior Capstone Design
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`project course. The task of developing this course was assigned to me. The
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`requirement for engineers to complete a senior design project has been retained as
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`a graduation requirement continuously ever since. In designing this course, I chose
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`to base it on a customer model, whereby the course instructors solicit real-world
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`customers in need of a product or system to be designed. This model for the
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`course is still in place as of today, and it also has been adopted by other
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`departments in the College of Engineering.
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`16.
`
`Products of the type described in the ‘543 patent are commensurate
`
`in complexity with some of the senior design projects that I have supervised over
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`the years. Projects of this type would have been straightforward and routine before
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`the time of invention. In fact, the very first project that I assigned when the course
`
`began in 1990 was a system for the remote monitoring of AC electrical power
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`consumption and current at outlet points, and the reporting back of the data to a
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`computer via an RS-232 network. RS-232 communication can be considered a
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`7
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`precursor to the Ethernet type of communication that is the backbone of the current
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`
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`Internet.
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`17.
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`Prior to the time of invention, an engineer having recently entered the
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`work force would definitely have had the skills to design a product with outlets,
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`switching components (such as relays), sensor elements (such as current sensors),
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`input/output devices (such as electronic or numeric displays), control components
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`(such as one or more processors or logic units) and communications components
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`(such as a network interface). The use of communication components for both the
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`remote receiving of information regarding operation of the product and the
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`supplying of commands to control the product was also well within the skill set of
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`an engineer entering the work force before the time frame of the ‘543 patent. This
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`latter fact is evident given the project that I assigned to ECE students as early as
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`1990.
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`18.
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`I further note that an engineer who had recently entered the work
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`force in the time frame of the ‘543 patent would have recognized that operation of
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`the components that make up the disclosed invention would not be affected by the
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`form factor of the housing. Specifically, an engineer entering the work force
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`would have expected the components to perform the same functions whether
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`packaged in a vertical housing or a horizontal housing, or in a one-piece housing or
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`a multi-piece housing. This fact regarding the similarity of horizontal vs. vertical
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`8
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`
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`form factors for electrical devices − particularly for devices in which gravity is an
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`
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`irrelevant parameter − is evident in a variety of electrical and electronic devices
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`that were in widespread use in the time frame of the invention. Early (pre-laptop)
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`personal computers, for example, could be placed on a desk in either a horizontal
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`or vertical position with equal ease, and would function the same irrespective of
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`orientation. (As of today, in fact, I have two desktop computers in two offices; one
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`is oriented vertically, and the other horizontally.) The same was true for
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`unintelligent plugstrips which, I observed, were mounted both horizontally (on lab
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`benches) or vertically (inside panel racks).
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`19.
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`One concept that is taught consistently to engineering students in
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`engineering curricula throughout the United States is that it’s important to consider
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`numerous design options before committing to the final design of a product. The
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`foundation of this process is the well-known, iterative “design cycle,” depicted in
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`the figure below taken from my book Design Concepts for Engineers. Engaging in
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`the design cycle forces design engineers to consider all possible design options for
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`a product under development, including its form factor and features. Another thing
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`taught routinely to engineering students is the concept that, in designing a product,
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`the requirements of the end user, as well as the environment in which the product
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`will be used, are very important considerations. While some users may insist on a
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`set of product specifications that include certain features from the list of possible
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`9
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`choices, others may insist on a different set of specifications, in whole or in part,
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`
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`from the same list. Meeting customer needs and specifications is a critical
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`component of product design.
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`Figure: “The Design Cycle”
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`IV. Intelligent Processing Circuitry in PDU Products
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`
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`20. Although the MSVM Literature and Baytech RPC-7 Literature do not
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`describe in detail all of the processing circuitry contained in their associated PDU
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`products, one of skill in the art would have understood certain basics of the
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`circuitry from the functions and structures that are disclosed in the product
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`documentation. One of skill would have appreciated that the MSVM Literature
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`
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`10
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`
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`and Baytech RPC-7 Literature reflect that each of the associated PDU products
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`contained intelligent processing circuitry related to the current measuring and
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`reporting systems and the ability of the PDUs to respond to commands.
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`21. For example, the MSVM Literature teaches that the MSVM PDU
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`included an LED display of information related to the current measured by a
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`current sensor in the PDU. (See, e.g., MSVM User Manual at 11.) One of skill in
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`the art would have readily understood the LED display to have been controlled by
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`intelligent circuitry within the PDU. The data signals provided by the current
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`sensor would also have been processed by intelligent circuitry within the PDU.
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`Without such circuitry, including the intelligent portion, the PDU could not
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`measure, display, or report current information as described in the MSVM
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`Literature. For example, in order to determine which LED state to display in a
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`PDU such as the MSVM (e.g., green, flashing green, or red) the PDU must first
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`demarcate the range of currents into discernible ranges, then measure and digitize
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`the actual PDU current, and then make a choice as to which LED state to display.
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`The PDU circuitry must then implement the chosen LED state. These operations
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`require intelligence on the part of the circuitry attached to the current sensor.
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`Given that the plugstrip portion of the MSVM had its own LED display, a skilled
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`person would understand this intelligent circuitry to reside inside the PDU.
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`22.
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`Further, one of skill in the art -- even one having only one to three
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`11
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`
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`years of industry experience -- would have understood that, in the architecture
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`
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`pictured in the MSVM Literature, the network interface card within the Controller
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`was receiving commands over a 10Base-T network (or other network) and
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`generating commands that could be communicated through the RJ-11 connectors
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`over the network to one or more PDUs. Processing circuitry within each PDU
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`would necessarily receive such a command and determine whether the command
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`was directed to that PDU. If so, processing circuitry inside the PDU would
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`generate signals to cause the relay-controlled outlets (or other component, as
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`appropriate for the command) within the PDU to execute the command. Also, in
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`reporting information for transmission over the 10Base-T network (or other
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`network), processing circuitry within each PDU would necessarily acquire a
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`measurement from a current sensor (or other component, as would have been
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`appropriate for the type of information being reported) and then cause it to be
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`transmitted over the network connecting the PDUs.
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`23.
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`Similarly, given the current reporting and outlet control capabilities
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`described in the MSVM Literature, it also would have been readily apparent to one
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`of skill in the art that the MSVM PDU contained intelligent circuitry for
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`communications, control, and processing. The MSVM Literature makes clear that
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`the MSVM PDU plugstrip both responded to commands and generated information
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`for communication with the controller via its RJ-11 cable. Additionally, multiple
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`12
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`
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`plugstrips could be networked in a daisy-chained fashion using the RJ-11
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`
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`connections. For example, the figure shown below, found in the MSVM Literature
`
`(MSVM Quick Start at 10), shows four PDUs networked together to one
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`Controller, with the connections to the Controller made via RJ-11 connectors only.
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`A skilled person would know that the industry-standard RJ-11 connector has
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`(typically) four, or a maximum of six, conductors.
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`
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`24. As evidence that each MSVM plugstrip contained its own
`
`microprocessor, I note that the MSVM Literature indicates several on/off cycling
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`operations and delayed start operations that could be performed on individual
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`outlets inside the PDU. (MSVM User Guide at 6-10.) A skilled person would
`
`know that these operations would require a microcontroller to be inside the
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`plugstrip, with commands and information related to individual outlets transmitted
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`as addressed digital packets over the RJ-11-connected cable. Without a
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`microcontroller inside each PDU, it would be necessary to connect each outlet’s
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`relay and each current sensor via dedicated wires to the Controller. There are
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`13
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`simply not enough conductors in an RJ-11 connector and its cable to allow such
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`
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`connections to be made and to facilitate performing such operations upon
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`command by having dedicated wires from each outlet going to the Controller.
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`Thus, it would have been evident to a skilled person that the addressing, status, and
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`command signals would have been sent to and from the PDU via its RJ-11-
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`connected cable, with the local operations inside each plugstrip executed by a
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`microprocessor or microcontroller1. A skilled person would know that it would not
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`be possible for each of the current sensors and outlet relays in the PDU to be
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`connected directly to the Controller via the RJ-11 connector and cable.
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`25.
`
`I also note that the MSVM Literature teaches that the MSVM PDU
`
`could access a network via the RJ-11 modular port either with or without the
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`Controller portion. (See MSVM Quick Start at 10.) One of skill would have
`
`understood from the MSVM Literature that the MSVM PDU could connect to a
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`network through the Controller associated with the device when connected via the
`
`RJ-11 connector. Because the RJ-11 connector was a standard connector well
`
`before the time of invention, one of skill in the art would also have appreciated that
`
`the MSVM PDU could connect to any device having a compatible RJ-11
`
`connector. For example, any of a family of devices designed to connect to a
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`network could be interconnected in this way. One of skill would also have known
`
`1 For the purposes of this declaration, the terms “microcontroller” and
`“microprocessor” can be considered interchangeable.
`14
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`
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`that the MSVM PDU could connect to a network through a standard computer
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`
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`modem via the RJ-11 connector, thus eliminating the need for the Controller.
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`Furthermore, the MSVM PDU could also connect through a server or a
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`workstation capable of sending information to a network, or other equivalent
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`component or device. Such modem, server, and workstation network
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`configurations were common before the time frame of the ‘543 patent. Given
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`these configurations, one of skill would also have known from the MSVM
`
`Literature that one could remotely manage the MSVM PDU using the Telnet
`
`network protocol. (See also MSVM User Guide at 12.)
`
`26. For similar reasons, one of skill in the art would have understood that
`
`the Baytech RPC-7 Literature reflects the fact that the RPC-7 device had
`
`intelligent circuitry, e.g. a microcontroller, within the PDU. One of skill would
`
`have realized from the Baytech RPC-7 Literature that intelligent circuitry existed
`
`inside the RPC-7 PDU for the purpose of communications and processing; this
`
`fact would be evident given the network and outlet management capabilities
`
`described in the Baytech RPC-7 Literature. One of skill would also have
`
`understood from reading the Baytech RPC-7 Literature that information obtained
`
`via the current measurement circuitry would have been processed by intelligent
`
`circuitry. (See, e.g., Baytech Manual at 59; Baytech Press Release; Baytech
`
`Webpage at 3.) The Baytech RPC-7 Literature describes a “completely integrated
`
`
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`15
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`
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`device” with all of the components contained inside the PDU, including the
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`microcontroller and network controller. (See Baytech Press Release.) Without
`
`intelligent circuitry, the RPC-7 PDU would not have been capable of being a
`
`“completely integrated device” with measuring and reporting of current
`
`information as is described in the Baytech RPC-7 Literature.
`
`V. Multiple Intelligent Power Sections/Modules
`
`27. A person skilled in the art in the time frame of the ‘543 patent
`
`would have recognized that partitioning the circuitry tasked with controlling a
`
`number of relays, such as an intelligent-power section/module as described in the
`
`‘543 patent, could be accomplished in several ways. As part of the normal
`
`design process, a skilled person would have considered a system in which the
`
`control function is performed centrally by a single unit controlling all the relays.
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`Alternatively, the control circuitry could have been distributed into two, four, or
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`even more subdivisions or sections in which each subdivision of the circuitry
`
`controlled some subset of the relays. Yet another system might involve a
`
`combination of centralized and distributed control. Each of these options would
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`have been contemplated by the skilled person as a normal part of the design
`
`process. Contemplation of these design choices would have been more than
`
`obvious − it would have been expected as a normal part of the design process for
`
`any engineer designing a power distribution unit to meet a set of specifications.
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`16
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`28.
`
`Furthermore, I note that the prior art in existence long before the time
`
`of ‘543 patent, including the prior-art Ewing ‘974 patent, illustrates the well-
`
`known nature of intelligent power sections/modules. Ewing ‘974 broadly teaches
`
`“[p]rior art SNMP network management uses embedded microprocessor in almost
`
`every inter-networking device to support two-way inter computer communications
`
`with TCP/IP, of which SNMP is a member of the TCP/IP protocol suite.” (Ewing
`
`‘974 at col. 2:50-54, Figs. 1, 3-4.) Ewing ‘974 also teaches that it was well known
`
`to distribute power control into multiple intelligent power sections/modules. (See,
`
`e.g., Ewing ‘974 at col. 6:1-24, Figs. 1, 3; see also id. at col. 5:38-53, 8:28-31.)
`
`VI. Reasons to Use A Digital/Numeric Display in a PDU
`
`29.
`
`In my opinion, the choice to use widely-available digital/numeric
`
`displays, such as those pictured in the Lee and Liu patents, would have been
`
`considered as part of the design process by an engineer tasked with developing a
`
`means to present visual information related to current in a PDU. Given that the
`
`principles of design cycle and choice would have been taught in the engineering
`
`curricula of persons of skill, this routine understanding would have been known
`
`even to an engineer having just one to three years of industrial experience in the
`
`late 1990s or early 2000s. In my own case, as a student in the mid-1970’s, I first
`
`used a numeric display to replace an analog display mechanism (e.g., older
`
`“needle” type of meter). In the intervening years leading up to the time frame of
`
`
`
`17
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`
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`the ‘543 patent, numeric displays became cheaper and more widely available, so
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`
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`that by the late 1990s, the choice of using numeric displays, available as
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`commodity items sold by scores of vendors, would have been contemplated
`
`routinely as part of the design of a product which had to meet the requirement of
`
`presenting current-related information to a user. An electrical or computer
`
`engineer, even one having only one to three years of industrial experience, would
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`have known that such a display could be successfully incorporated into a product
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`using routine engineering principles and techniques. Given the various sizes
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`available for numerical display devices in the time frame of the ‘543 patent, there
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`is nothing about the form factor of either a vertical or a horizontal plugstrip that
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`would have led such an engineer to conclude that such a common component could
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`not be successfully integrated into either form factor in a straightforward and
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`predictable way. The purpose of a digital current display is to show numerical
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`information, and putting a digital current display in a PDU would do just that.
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`30. A person of skill would have recognized that a current-measuring
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`system, such as the one described in the MSVM Literature, the Baytech RPC-7
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`Literature, and the McNally and Ewing ‘974 patents, could interchangeably feed a
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`numeric display or an LED display (or even an analog meter). Regarding the first
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`two choices, a user might consult a numerical display to discern current levels
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`constituting normal, overload or underload conditions. Another user might prefer
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`one or more LEDs programmed to take on different states to display these same
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`current-level thresholds. Given the choice of selecting LED indicators, a user
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`would have knowledge of which current ranges and thresholds corresponded to the
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`various LED display states. The user could thus program certain thresholds for the
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`current state into the product, so that LEDs changed their state in relation to those
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`thresholds. If the choice were to use a numerical display, the user might know the
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`relevant thresholds and be able to compare them to the displayed current values. In
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`both cases, however, the display method would involve the same current levels
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`corresponding to the chosen states, and both would result in displaying the same
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`information. These approaches would thus have been recognized by a skilled
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`person as being interchangeable, alternative digital approaches for implementing a
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`means to display current-related information in a power distribution unit, with the
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`choice depending on the situation and preferences of the user.
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`31.
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`The prior art provides examples of components that display current
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`or power information. These examples include the LED display of the MSVM, as
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`shown in the MSVM Literature, the display as described in the McNally patent, the
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`numeric digital displays of Lee and Liu, the linear LED display, or “Load Meter”
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`described in the PA-800 Manual, or combinations of these displays, such as is
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`found in the Paulsen patent. Other types of displays were also known, including
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`analog (“needle”) meters. Engineering students in the time frame of the ‘543
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`19
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`patent would have been exposed to these types of devices as a result of their course
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`work, laboratory classes, and other studies prior to graduation, and would have also
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`recognized these components to be simple, alternative approaches for
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`implementing a display on a power distribution unit.
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`32. As a matter of routine engineering design, one of skill in the art at the
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`time of the invention would have considered whether digital/numerical information
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`about the current supplied by the PDU would have been helpful to the user. One of
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`skill would have appreciated that the obvious potential benefit of a multi-digit
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`display (such as those disclosed in Lee and Liu) over a single-LED display would
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`be to provide more information to the user about the actual value of the current, as
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`measured in amperes. If the user knew this detailed information about the current,
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`that user would be able to more accurately predict and prevent undesirable current
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`overloads, as is discussed in Lee and Liu.
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`33. As one example in practice, based on the MSVM Literature or the
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`McNally patent, a user could set the normal current level at 15 amperes (“amps”)
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`or below, the warning level threshold at 15 amps, and the maximum allowable
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`current at 20 amps. (Id.; MSVM User Guide at 5; McNally at col. 7:34-47, Fig. 4.)
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`In this example, for currents between 15 and 20 amps, the LED display would
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`flash green to warn the user that the warning zone had been entered and would help
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`prevent the transition to a current overload at 20 amps. By adding a digital display
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`20
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`such as the ones disclosed in Lee or Liu, however, the PDU would warn the user in
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`a different way by providing the actual value of current both below and above the
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`warning threshold. This information would help to prevent an overload by
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`showing the user incremental current values in amperes, e.g., the discrete values of
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`15 to 16…17… 18… 19… and 20 amps.
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`34.
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`Furthermore, one of skill might have been motivated to choose a
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`numeric, digital display when an end user desired or requested one. In such a unit,
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`the digits would display current information directly in units of amperes. Such a
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`display would provide no direct information, however, about the percentage of
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`maximum load being drawn by the PDU. In an alternative case, the user might
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`prefer a PDU having a linear LED load meter of the type found in the PA-800.
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`Such a user might want to know what percentage of the maximum allowable load
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`current was being supplied by the PDU without desiring instantaneous information
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`about the number of amperes. Yet other users might not desire this granularity of
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`information, preferring to rely on the network-reported current levels instead. The
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`preferred PDU design for such a user might have been the simple LED indicator
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`such as the one found in the MSVM. The point is that each of these displays
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`would have constituted one possible choice in the designer’s tool kit, with each
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`one, including the numerical, digital display option, motivated by different
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`circumstances or user preferences.
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`35.
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`For similar reasons, one of skill in the art at the time of the invention
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`would have had an additional reason to select a digital display, such as the ones
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`disclosed in Lee or Liu, for a PDU that had no display in the first place, such as the
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`one shown in the Ewing ‘974 patent (in view of Wiebe) or the Baytech RPC-7
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`Literature. As a matter of routine engineering design, one of skill would have
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`recognized benefits of a d