Author: YungChieh Hung (20070313);
recommendation: YehLiang Hsu (20070313).
Note: This article is Chapter 4 of YungChieh Hung’s
PhD thesis “Development of an Innovative Patentbased Design Methodology.”
Chapter 4. Design matrix representation of patents
The patentbased design process developed in this
research can be divided into four major stages as shown
in Figure 41. This
chapter discusses how the related patents obtained from patent analysis are
symbolized using the concept derived from axiomatic design (stage 1 and 2). The
example of a
portable magnetic
impact tool (U.S. Patent 6,918,449) is used again to illustrate the detailed
steps of implementation and required considerations of the patentbased design
process.
Figure 41.
Conceptual flowchart of the patentbased design process
4.1
Patent analysis
There are 3
major tasks in the patent analysis process:
(1)
Patent search and screen
The
first step of patent analysis is to search related patents. Keywords for searching patents can be
obtained by considering the names of products, brands, characteristics of
products and technologies, names of related competitive companies or patent
holders, and patent classification numbers. Searched results often have many
unrelated patents. Therefore, the designers have to read the specifications or drawings to screen
for related patents.
(2)
Develop the abstract lists of
patents
The next step is reading and analyzing each concerned patent to develop the abstract lists of patents. The
designers construe a
patented invention and record the disclosed techniques and functions in the
abstract list to establish the patent database. The
designers should not only understand and confirm the subject matter that is to
be resolved in this step, but also point out which techniques are used to
obtain the objectives of the investigated patents, and the roles and
contributions of each technique. Table 41 shows the abstract
list of U.S. Patent 6,918,449.
Table 41. The
abstract list of U.S. Patent
6,918,449
Title

Magnetic
impact tool

Patent No.

U.S. 6,918,449

Date of field

2004/3/24

Date of issued

2005/7/19

Assignee

Matsushita Electric
Works, Ltd.

Inventors

Shinagawa; Sou,
Nakayama; Satoshi, Sekino; Fumiaki

Analyst

David

Keywords

magnetic, impact,
rotate

UPC

173/2;
173/117; 173/176; 173/213;
173/93

IPC

B25B 21/02; H02K 7/14; H02K 7/10; H02K 49/10; H02K 49/00

Date of analysis

2006/7/1

Background of the invention
Figure (a) shows the major components of a portable power tool
driven by an electric motor. The rotational motion of the motor is
transmitted to a chuck that holds a tool output shaft by means of a hammer.
The motor is generally small due to restrictions imposed on the overall size
and weight of the portable power tools. Limited power of the small motor
might not be enough to drive the intended load. A hammer type of mechanism is
used to generate high output torque from a small drive.
Figure (a). Components of a portable power tool
As shown in Figure (b), the hammer
stores the rotational energy of the motor over a large angle of rotation, for
example, a half turn. Then the hammer hits the chuck to create an impact
torque over a small angle (for example 10 degrees) of rotation of the chuck.
In this type of portable power tool, loud noise is generated when the hammer
hits the chucks.
Figure (b). Top plan view of a hammer type
impact generator

Functions of the patent
l
Tighten/ loosen screw
l
Generate impact torque
l
Change magnetic flux

Results of the patent
The present applicants have previously proposed a magnetic impact
tool with which screws are tightened by using magnetic coupling to deliver a
strike without any contact, and obtaining a tightening rotational impact
force without a collision sound.

Means for solution, composition and
important figures
l
During the screwtightening
work, when the load torque is initially low, the magnetic hammer (2) and
magnetic anvil (1) begin to rotate together without any impact action. When
the load torque exceeds the magnetic attraction torque, the magnetic hammer
and magnetic anvil are not synchronized anymore. Impact action can be
generated, and screw tightening and loosening work can be carried out even if
a lowtorque motor is used.
l
This tool comprises a
magnetic bypass device (24) for distributing magnetic flux between the
magnetic anvil and the magnetic hammer, and a changing device (28) for
changing the distribution of magnetic flux by the magnetic bypass device (24).
l
The torque generated between
the magnetic hammer and magnetic anvil can be changed by the changing device
to vary the distribution ratio of the magnetic flux from the magnetic hammer
to the magnetic anvil.
Figure (c). U.S. Patent 6,918,449

Independent claims
l
A motor for generating
rotational force.
l
A drive shaft rotatably
driven by the motor.
l
A magnetic hammer rotatably
moved in a coupled state with the drive shaft.
l
A magnetic anvil which faces
the magnetic hammer and to which the rotational force is transmitted by
magnetic coupling, with one of the opposing surfaces of the magnetic hammer
and magnetic anvil having a magnetic pole, and the other having a magnetic
pole or magnetic body.
l
An output shaft rotated by
the magnetic anvil.
l
A magnetic bypass device that
bypasses the magnetic flux between the magnetic anvil and the magnetic
hammer, and changes the state of magnetic coupling there between.
l
A changing device that
changes the bypass quantity of the magnetic flux with the magnetic bypass
device, with the torque transmitted from the magnetic hammer to the magnetic
anvil being changed in accordance with the change in bypass quantity of the
magnetic flux varied by the changing device.








(3)
Develop technology/function matrix
Lastly, the
technology/function matrix is constructed to classify each concerned patent. The
technology/function matrix is used to investigate which techniques can produce
the specific functions. The column of the matrix represents the functions while
the row lists the disclosed techniques. The technologies and functions are
obtained from the patent abstract lists of each concerned patent. Table 42 shows an example of technology/function
matrix of U.S. Patent 6,918,449.
Table 42. Technology/function matrix
Functions
Technologies

Tighten/ loosen screw

Generate impact torque

Change magnetic flux

Motor

●

●


Magnetic hammer

●

●


Magnetic anvil

●

●


Drive shaft

●

●


Output shaft

●



Magnetic bypass device



●

Changing device



●

4.2
Axiomatic design
In this
research, each concerned patent in the technology/function matrix is then symbolized by a “design matrix”, which
is inspired by the “axiomatic design” methodology proposed by Suh [2001].
Axiomatic design is a system design methodology using matrix method to
analyze the transformation of customer needs into functional requirements,
design parameters, and process variables. The axiomatic design approach consists of two
axioms. Axiom 1, which is called the independence
axiom, deals with the relationship between functional
requirements (FRs) and design parameters (DPs). Axiom 2, which is called the information axiom,
deals with the complexity of the design. In this research, Axiom 1 is used for
representing each patent that to be designed around. A
brief introduction to
Axiom 1 is described below.
Let there be m components represented by a set of
independent FRs where FR is the vector of functional requirements. DPs in the
physical domain are characterized by vector DP with n components. The design process is choosing the right set of DPs
to satisfy the given FRs. The design matrix representing the relationship
between FRs and DPs vectors is expressed as
_{} (4.1)
_{} (4.2)
Equation (4.1) is a design equation for the design of a product,
where_{} is a “design matrix” that characterizes the product design.
The components in the design matrix are either “0” or “1”.
A cell takes a “0” if varying the design parameter has no effect on
the corresponding functional requirement and a “1” if it does.
In general, Equation (4.1) may be written in terms of its elements
as,
_{} (4.3)
where n is the number of DPs.
4.3
Design matrix representation
In the “technology/function” matrix in Table 42, the “technologies”
resembles the design parameters (DPs), and the “function” resembles the
functional requirements (FRs) in Equation (4.3). In this case,
FR_{1}
= Tighten/ loosen screw
FR_{2}
= Generate impact torque
FR_{3}
= Change magnetic flux
The corresponding DPs are as follows:
DP_{1}
= Motor
DP_{2}
= Drive shaft
DP_{3}
= Magnetic hammer
DP_{4}
= Magnetic anvil
DP_{5}
= Output shaft
DP_{6}
= Magnetic bypass device
DP_{7}
= Changing device
The technology/function matrix in Table 42 can be expressed as
_{} (4.4)
where
_{} is the transformation
matrix which transfers the DRs into FRs. For example, in Equation (4.4)
_{} (4.5)
The first
equation above means that “Transforming components motor,
drive shaft, magnetic hammer, magnetic anvil, and output shaft achieves
function of tightening/ loosening screw.” Similarly, the second equation above
means that “Transforming components motor, drive shaft, magnetic hammer, and magnetic anvil achieves the
function of generating impact torque”; the third equation above means that “Transforming components magnetic bypass device and changing
device achieves the function of changing magnetic flux.”
In summary, a patent can be represented
by the following equation:
_{} (4.6)
or
_{} (4.7)
where
[FR] is a column vector of the “functions”
of the patent, and [DP] is a column
vector of the “technologies (components)” of the patent. Both [FR] and [DP] are extracted directly from the technology/function table of
the patent. Matrix A is a design
matrix that characterizes the patent. The components in matrix A are 0s and 1s
representing the relation between functions and technologies. Finally row
vector T is a transformation matrix which transforms the technologies into
function.
Reference
Suh, N. P., “Axiomatic Design: Advances
and Applications,” New York: Oxford University
Press, 2001.