Homework 10: Patent Liability Analysis

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18 Οκτ 2013 (πριν από 4 χρόνια και 8 μήνες)

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ECE 477

Digital Systems Senior Design Project

Rev 8/09

Patent Liability Analysis

Team Code Name: ______
POV Machine
______________________ Group No. ___

Team Member Completing This Homework: ________
Eric Glover

mail Address of Team Member: __

@ purdue.edu






among the best papers submitted for this assignment. Very few
corrections needed for version submitted in Final Report.


Very good

all requirements aptly met. Minor additions/corrections needed for
version subm
itted in Final Report.



all requirements considered and addressed. Several noteworthy
additions/corrections needed for version submitted in Final Report.



all requirements basically met, but some revisions in content should
be made fo
r the version submitted in the Final Report.



all requirements met at a nominal level. Significant revisions in
content should be made for the version submitted in the Final Report.


Below the passing threshold

major revisions required to

meet report
requirements at a nominal level.
Revise and resubmit.

Resubmissions are due within
one week

of the date of return, and will be awarded a score of
“6” provided all report requirements have been met at a nominal level.


ECE 477

Digital Systems Senior Design Project

Rev 8/09




The project is a device that operates on the principle of persistence of vision (POV). A column of
LED lights is
spun around at sufficient speed with each light turning on at precise moments to
create the illusion of an image floating in midair. A moto
r spins the LED’s at approximately
1800 RPM. The project includes a stationary base unit and a rotary component. Data is
transferred between the two segments using a wireless transceiver. Power is transferred using a
set of slip rings. Each unit contains a

microprocessor. The stationary component is used to
generate pixel maps and interact with the user. The rotary component controls the LED’s to
generate an image based on the input pixel map. The image is able to be updated while the
machine is in operatio
n. It is also able to display the image in a user
determined direction, either
by manual input or by receiving input from a
RF beacon. The project uses a system of four
antennas to detect the angle of arrival of a signal from the RF beacon. This input is t
processed by the device to enable the option of displaying the output image in the same direction
as the RF beacon. Lastly, the project incorporates
a zero
position sensor both to determine speed
and to provide a reference for image display offset.


sults of Patent and Product Search

Several patents were researched to determine patent liability for the project. The project was
determined to have two primary functions. These functions are the ability to display an image
using persistence of vision and
also the ability to measure the angle of arrival of an RF
Three patents were researched from the area of persistence of vision, and one patent was
researched from the area of RF angle of arrival


The first patent covering the field of p
ersistence of vision is Patent 4,689,604. The patent
application was filed on March 3, 1983. This patent describes a device that uses three LED bars
to display an image using the persistence of vision concept. The device spins at between 1200
and 1800 RPM.

incorporates an on
board microprocessor and a zero
position sensor. However,
this device includes only a rotational compone
nt and no stationary component


The second patent to be discussed is Patent 5,302,965, which was filed on October 15, 1991.
described device utilizes both a stationary and rotary section. Power is transferred between the
ECE 477

Digital Systems Senior Design Project

Rev 8/09


components using slip rings

and d
ata is transferred using a rotary transformer. The device uses

16 LED bars. The logic for the device consists entirely of
flops and gates instead of using a
microcontroller. The device also relies on precise motor speed control instead of including a
position sensor. The projected image is provided by input through an on
board data socket


The final patent rese
arched on persistence of vision technology is Patent 5,748,157. The patent
was filed on December 27, 1994.
This device is unique compared to the other patents because it
does not operate with a motor. Instead the device is hand
held and relies on the user
to wave it to
create an image. The device includes an array of LED’s and a periodically actuated switch to
measure the cycle time of a cycle a
nd the initiation of the cycle


Patent 2,489,304 describes a system used for determining the bearing of a sin
gle short burst or

of energy from a transmitter. A pulse is received on a system of two pairs of directional
antennas. One of the two pulses is delayed before being compared with the other pulse by a
receiver. The two pairs of antennas are used to el
iminate ambiguity about the direction of the
signal. In this manner the angle of arrival of the input RF signal is determined



Analysis of Patent Liability

POV Machine

has many similarities with other previously patented devices. The project
es a zero
position sensor, a quick rotational speed (~1800 RPM), and an on
microcontroller with the system described in Patent 4,689,604. However, since a patent is only
valid for 20 years this patent is out of date. These components may be u
sed free
ly in the design
the potential for

In Patent 5,302,965 there are additional similarities with
the current design. This patent describes a device that incorporates both stationary and rotary
components. The inclusion of slip rings to t
ransfer power is also shared between the two designs.
However, slip rings are common knowledge and are not the subject of the patent. Although data
is transferred between the stationary and rotary components in both designs, this is done in a

different way between the two systems. In the version described in the patent, the
data is transferred through a rotary transformer. This substantially limits the data rates. However,
in the POV Machine’s design the data is transferred through a wireless
transceiver. This allows
ECE 477

Digital Systems Senior Design Project

Rev 8/09


for much faster data transfer rates and is a substantially different method than the rotary
The POV Machine shares little in common with Patent 5,748,157. The POV
Machine and the system described in the patent both dis
play images using a single column of
LED’s, but one is controlled using a motor and the other relies on a user to wave the device.
These are substantially different methods. Finally, the angle of arrival detection used by the POV
Machine is done in a very
similar way to the method described in Patent 2,489,304. Both use an
array of four antennas and delay one of the signals before comparing them with a receiver.
Fortunately, this patent is well out of date and the methods described in the patent can be free
used by the POV Machine.


Action Recommended

The existence of Patent 4,689,604 and Patent 2,489,304 show that the idea of using a persistence
of vision machine
to display an image
and also detecting the angle of arrival of an RF signal are

free to use w
ithout worry about infringement. These technologies have been patented for long
enough that the original ideas are no longer protected. The POV Machine also does not need to
be adjusted to avoid infringing on the design described in Patent 5,748,157. Altho
ugh both
display images using persistence of vision, the methodologies are very different. One uses a
motor to generate the cyclical motion, and the other relies on a user’s gestures. The only
potential for infringement lies with Patent 5,302,965. Both the

POV Machine and the device
described in the patent accomplish their tasks by using a stationary and rotary component.
However, it could be argued that since the system described in the patent does not use a
microcontroller, it is fundamentally different f
rom the team’s design. Fortunately though, this
patent expires in less than two years so if it is determined that there is infringement under the
doctrine of equivalents, the team can simply wait out the expiration of the patent before
producing the device



Four patents were analyzed to determine the possibility for infringement if the POV Machine
were to be produced and sold. Three of these patents described systems that used the theory of
persistence of vision to produce images. The fourth patent

discussed a method for measuring the
angle of arrival of an RF signal, which is an added feature of the POV Machine.

ECE 477

Digital Systems Senior Design Project

Rev 8/09


The idea of displaying images using the concept of persistence of vision is not a new invention


is no longer protected by intelle
ctual property rights. This is evidenced by Patent
4,689,604 which describes a system for displaying images using this technology, but which was
filed in March of 1983
. Similarly, the concept of detecting the angle of arrival from an RF
transmitter using a
n array of antennas and a delay line is described in a patent that is out of date
(Patent 2,489,304). Since these are the primary functions of the device, the patent liability of the
design is low.
ECE 477

Digital Systems Senior Design Project

Rev 8/09


List of References


Edward F
. Sokol

Moving visual display apparatus

U.S. Patent 4,689,604, March 3,


Barry J. Belcher et al, “
”, U.S. Patent 5,302,965, October 15, 1991.


Richard O. Eason, “
Display apparatus utilizing persistence of vision
”, U.S. Patent
5,748,157, December 27, 1994.


Marchand et al, “
Direction Finder
”, U.S. Patent 2,489
,304, June 27, 1945.