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Author: Yung-Chieh Hung (2007-06-27); recommendation: Yeh-Liang Hsu (2007-06-27).
Note: This article is Chapter 5 of Yung-Chieh Hung’s PhD thesis “Development of an Innovative Patent-based Design Methodology.”

Chapter 5. Development of the design around algorithm

This section discusses the development of the design around algorithm and the integration with TRIZ to generate real engineering design concepts from the design problems suggested by the design around algorithm. The example of the portable magnetic impact tool (U.S. Patent 6,918,449) is also used to illustrate the detailed steps of implementation of the patent-based design process.

5.1 Purpose of the design around algorithm

As discussed in Chapter 4, a patent can be expressed as

                             (5.1)

                                                                                              (5.2)

where A is the design matrix that characterizes the patent. The components in matrix A are 0s and 1s representing the relation between functions and technologies of the patent.

Consider a series of design matrices of existing patents , i = 1, …, n, to be designed around. The purpose of the design around algorithm developed in this study is to generate a new design matrix  that is similar to one of the existing matrices , but does not infringe with any of the existing design matrices. That is, to generate  such that

         and                                                                              (5.3)

where “” means “is similar to”, and “” means “does not infringe with”.

Figure 5-1 shows the flowchart of the design around algorithm. To start with, the designer must identify the related patents to be designed around and to collect functions (DPs in Equation (5.1)) and core techniques (FRs in Equation (5.1)) of each related patent, as in standard patent analysis. Each patent is then symbolized by a “design matrix” converted from the DPs and FRs of the patent.

After transferring the related patents into design matrices, the designer has to assign the priority of DPs to be designed around. The priority of DPs to be designed around is given to those having the least influence in design matrix, which are the DPs having the least contribution to the FRs, and the DPs having minimal interaction with other DPs. The columns and rows of design matrix are sorted according to the number of non-zero elements.

After the priorities of DPs are decided, the “design around operation matrices” are applied to the design matrix to generate a new design matrix which is similar to but does not infringe with the design matrix of the patent to be designed around. In this research, four design around operation matrices are proposed. They are elimination, replacement, integration and decomposition. Note that the design around operation matrices will be applied to the DPs which were assigned highest priority to be designed around.

The design around operation matrices are applied in the order of “elimination” (to eliminate redundant component), “replacement” or “integration” (to make at least one constitutive DP substantially different), and “decomposition” (to replace a multi-functional technological characteristic with a few separate technological characteristics). New design matrices which do not infringe with the existing patents and the corresponding design problems are generated.

Based on the existing patent, TRIZ is used to transform the new design matrix back into a real engineering design concept. However, this transformation may fail because there may not be a feasible design corresponding to the new design matrix generated by the algorithm. If TRIZ fails to generate a feasible design, the algorithm is triggered again to apply the design around operation matrices to the second priority DPs. Finally, the process terminates when a feasible new design concept is generated.

Figure 5-1. Flowchart of the design around algorithm (New design matrices which do not infringe upon…)

5.2 Design around strategies

The judgment of infringement in patent lawsuits consists of three rules: the “all elements rule”, “doctrine of equivalents”, and “doctrine of file wrapper estoppel”. The first two judgments are commonly used to make sure whether or not a new design concept infringes with the original patents.

(1)   All elements rule

If all elements of claims can be literally read on the components that appear in the accused subject matter, the all elements rule is satisfied with a literal infringement. In other words, the infringement occurs if the accused subject matter contains all of the elements that constitute the claim.

(2)   Doctrine of equivalents

If the all elements rule is not satisfied, but the elements in the accused subject matter use substantially the same way as those in the claims, perform substantially the same function, and obtain substantially the same result, the techniques under investigation are considered to be equivalent to those in the claims. This is also known as the “triple identity (way/function/result) test”.

According to the “all elements rule” and “doctrine of equivalents”, five strategies of designing around can be recommended according to the constitutive requirements of patent infringements:

(1)   Eliminate one or more technological characteristics

This strategy is applied by using the concept of the all elements rule. One or more of the listed technological characteristics of an existing patent are eliminated considering their necessities or strategy of product development.

(2)   Replace one or more of claimed technological characteristics

This strategy is considered based on the doctrine of equivalents used in the process of patent infringement judgment. The implementation of this strategy is to replace at least one technological characteristic of prior art or other patents.

(3)   Change the functions or objectives of technological characteristics

This strategy is also considered based on the doctrine of equivalents. Designing around will be successful if one or more functions or objectives of unclaimed technological characteristics are not substantially the same as those of corresponding claimed ones.

(4)   Integrate two or more claimed technological characteristics

This strategy is also considered based on the all elements rule. The purpose of the integration of technological characteristics is to reduce at least one constitutive element of a claim while all functions are kept. This kind of integration should not be the simple combination of original claimed technological characteristics. The means or operation principles of the specific function must be substantially different from those of claims.

(5)   Decompose one technological characteristic into multiple technological characteristics

This strategy is applied by using the concept of the doctrine of equivalents. This strategy is opposite of strategy (4). The implementation of this strategy tries to replace a multi-functional technological characteristic with a few separate technological characteristics.

Table 5-1 summarizes the five design around strategies. The strategy “change the functions or objectives of technological characteristics” results in designs of different functions, therefore is not used in the design around algorithm developed here. The other 4 design around strategies, elimination, replacement, integration, and decomposition are considered in the design around algorithm discussed in the next section.

Table 5-1. Design around strategies

Design around strategy

Original patented technological characteristicsTechnological characteristics after designing around

Note

Elimination

 

Replacement

Technological characteristics:

 

Function: ,

Change

Technological characteristics:

,

Function: ,

Integration

has the same function as  

Decomposition

Decompose the function of intoand

5.3 Assigning priority to DPs to be designed around

Equation (5.4) shows the design matrix representation of U.S. Patent 6,918,449,

                                  (5.4)

There are 7 DPs in this patent. The priority of DPs to be designed around is given to those having the least influence in A, which are the DPs having the least contribution to the FRs, and the DPs having minimal interaction with other DPs. To assign the priorities, the columns of design matrix A are sorted according to the number of non-zero elements. Then the rows of design matrix A are sorted according to the number of non-zero elements.

In Equation (5.4), the design matrix A remains unchanged after sorting.  only contribute to one function , and and  only contribute to one function .  and  only interact with each other, while  interacts with 4 other DPs (, ,  and ) to achieve function . Therefore  and  have the highest priority to be designed around, and  has the second highest priority to be designed around. , ,  and  are considered lastly.

5.4 The design around operation matrix

After the priorities of DPs are decided, the “design around operation matrix” D is applied on the design matrix to generated a new design matrix :

                                                                                                 (5.5)

where  is called the “expansion matrix” of A, defined as

                                            (5.6)

and c is the number of expanded columns. Note that the patent represented by design matrix A is equivalent to that represented by design matrix , that is, A=. For example,

       

           (5.7)

The expansion matrix will be needed when new DPs are introduced in the design around process. Finally, the 4 design around strategies discussed in the previous section are converted into different design around operation matrices.

5.4.1 Elimination

If one or more components in concerned patent are found to be redundant, they can be eliminated directly to generate a solution with simplified components/functions. For example, in U.S. Patent 6,918,449, in order to avoid falling into the scope of all elements rule, eliminating the magnetic bypass device () or the changing device () can be considered first. Equation (5.4) shows the design matrix representation of U.S. Patent 6,918,449, where

        A=                                                                  (5.8)

Let

        D1=                                                               (5.9)

                                                       (5.10)

Clearly , because  has been eliminated, and the designing around is successful according to the all element rule. The new design can be expressed as

                                  (5.11)

                                                    (5.12)

As shown in Equation (5.12), there is a new design problem to be solved (), which can be translated into:

Design problem 1: “How to design a transformation  to achieve the function  (change magnetic flux) using component  (changing device)?”

The same process can be used for eliminating . Let

        D2=                                                               (5.13)

                                                       (5.14)

Clearly , because  has been eliminated, and the designing around is successful according to the all element rule. The new design can be expressed as

                                  (5.15)

                                                     (5.16)

As shown in Equation (5.16), there is a new design problem to be solved (), which can be translated into:

Design problem 2: “How to design a transformation  to achieve the function  (change magnetic flux) using component  (magnetic bypass device)?”

5.4.2 Replacement

“Replacement” means one or more components of the design matrix can be displaced by another component(s). The replacement does not take place haphazardly but reasonably. For example, in U.S. Patent 6,918,449, in order to avoid falling into the scope of doctrine of equivalents, replacing the magnetic bypass device () or the changing device () can be considered first. A new DP will be introduced in the replacement operation, therefore the expansion matrix of A is used:

                                                                (5.17)

To replace DP6 with DP8, let

        D3=                                                         (5.18)

                                              (5.19)

The technological characteristics of  must be different from those of , so that , and the designing around is successful according to the doctrine of equivalents. The new design can be expressed as

                            (5.20)

                                                      (5.21)

As shown in Equation (5.21), there is a new design problem to be solved (), which can be translated into:

Design problem 3: “How to design a transformation  and a new component  to achieve the function (change magnetic flux) using component  (changing device) and , while the technological characteristics of  are different from those of .”

The same process can be used for replacing . Let

        D4=                                                         (5.22)

                                              (5.23)

The technological characteristics of  must be different from those of , so that , and the designing around is successful according to the doctrine of equivalents. The new design can be expressed as

                            (5.24)

                                                     (5.25)

As shown in Equation (5.25), there is a new design problem to be solved (), which can be translated into:

Design problem 4: “How to design a transformation  and a new component  to achieve the function (change magnetic flux) using component  (magnetic bypass device) and , while the technological characteristics of  are different from those of .”

5.4.3 Integration

As discussed earlier, “integration” combines two or more different components, and the technological characteristics of the resulting design are substantially different from those of original components. For example, in U.S. Patent 6,918,449, in order to avoid patent infringement by the all elements rule, the new product can be obtained through integration of the two technological characteristics of  and . Again a new component will be introduced in the integration operation, therefore the expansion matrix of A is used:

                                                                (5.26)

To integrate  and  into , let

        D5                                                      (5.27)

                                              (5.28)

Clearly , because  and  have been integrated into , and the designing around is successful according to the all element rule. The new design can be expressed as

                            (5.29)

                                                      (5.30)

As shown in Equation (5.30), there is a new design problem to be solved (), which can be translated into:

Design problem 5: “How to design a transformation  to achieve the function  (change magnetic flux) using a new component , while the technological characteristics of  are different from those of  and .

5.4.4 Decomposition

In “decomposition”, one major component is decomposed into several subordinate components, while the technological characteristics of the new components are different from those of the original components. Two or more new components are introduced and the expansion matrix of A is used:

                                                           (5.31)

To decomposed  into  and , let

        D6                                                   (5.32)

                                         (5.33)

The technological characteristics of  and  must be different from those of , so that , and the designing around is successful according to the all element rule. The new design can be expressed as

                      (5.34)

                                                     (5.35)

As shown in Equation (5.35), there is a new design problem to be solved (), which can be translated into:

Design problem 6: “How to design a transformation  and two new components  and  to achieve the function (change magnetic flux) using two new components  and , while the technological characteristics of  and  are different from those of .”

To decomposed  into  and , let

        D7                                                   (5.36)

                                                (5.37)

The technological characteristics of  and  must be different from those of , so that , and the designing around is successful according to the all element rule. The new design can be expressed as

                      (5.38)

                                                      (5.39)

As shown in Equation (5.39), there is a new design problem to be solved (), which can be translated into:

Design problem 7: “How to design a transformation  and two new components  and  to achieve the function (change magnetic flux) using two new components  and , while the technological characteristics of  and  are different from those of .”

After applying the 4 design around operation matrices to the components with the highest priority to be designed around, 7 new design matrices, and therefore 7 new design problems are generated. In the following section, TRIZ is used to find real engineering design concepts that solves these new design problems.

5.5 Generate real engineering design concepts using TRIZ

5.5.1 Solving design problem 5

In this section, the contradiction matrix and the inventive principles of TRIZ are used to solve these new design problems. For example,

Design problem 5: “How to design a transformation  to achieve the function  (change magnetic flux) using a new component , while the technological characteristics of  are different from those of  and .

The contradiction matrix in the TRIZ theory contains 39 design parameters and 40 inventive principles for solving related engineering design problems. As shown in table 5-2. the designer searches in 39 design parameters to find the ones matching with the functions in the design problem, and the “inventive principles” appear in the corresponding bracket are the possible guidelines to generate the “transformation”.

For design problem 5 described above, Parameter 10 (force) is selected as the feature for achieving the function of “changing magnet flux” by . In the mean time, we hope that it is easy for  to change magnetic flux. Therefore Parameter 33 (ease of operation) is selected as the feature not to be deteriorated in Table 5-2.

As shown in Table 5-2, four inventive principles can be obtained. They are Principle 1 (segmentation), Principle 28 (Mechanical interaction substitution), Principle 3 (local quality), and Principle 25 (self-service).

Table 5-2. The contradiction matrix

Undesired result

 

 

Feature to change

1

33

39

Weight of moving object

Ease of operation

Productivity

1

Weight of moving object

 

 

 

 

 

 

 

 

 

 

10

Force

 

 

1, 28, 3, 25

 

 

 

 

 

 

 

39

Productivity

 

 

 

 

 

After reviewing the four principles, Principle 28 was utilized to generate the new concept in the portable magnetic impact tool. In TRIZ, Principle 28 has four explanations:

a.     Replace a mechanical system with an optical, acoustical, thermal or olfactory system.

b.     Use an electric, magnetic or electromagnetic field to interact with an object.

c.     Replace fields that are: stationary with mobile, fixed with changing in time, random with structured.

d.     Use fields in conjunction with ferromagnetic particles.

In particular, we decided to apply “use an electric, magnetic or electromagnetic field to interact with an object” to solve the new design problems.

In the new design concept, the new componentconsists of four solenoids. The four solenoids are mounted on the magnetic anvil, and the impact torque can be changed by varying the distribution ratio of the magnetic flux by operating a switch for setting the output of the electric current value. In this concept, the new component has already integrated the function of the changing device and the magnetic bypass device.

5.5.2 Solving design problem 4

Use design problem 4 in Section 5.4.2 as another example,

“How to design a transformation  and a new component  to achieve the function (change magnetic flux) using component  (magnetic bypass device) and , while the technological characteristics of  are different from those of .”

For design problem 4 described above, Parameter 10 (force) is selected as the feature for achieving the function of “changing magnetic flux” by . In the mean time, we hope to increase efficiency of magnetic flux by the . Therefore Parameter 21 (performance) is selected as the feature not to be deteriorated in Table 5-3.

As shown in Table 5-3, four inventive principles can be obtained. They are Principles 19 (periodic action), Principles 35 (transformation of physical and chemical states of an object), Principles 18 (mechanical vibration), and Principles 37 (complexity of control).

Table 5-3. The contradiction matrix

Undesired result

 

 

Feature to change

1

21

39

Weight of moving object

Performance

Productivity

1

Weight of moving object

 

 

 

 

 

 

 

 

 

 

10

Force

 

 

19, 35, 18, 37

 

 

 

 

 

 

 

39

Productivity

 

 

 

 

 

After reviewing the three principles, Principle 19 was utilized to generate the new concept in the portable magnetic impact tool. In TRIZ, Principle 19 has three explanations:

a.     Replace a continuous action with a periodic one (impulse).

b.     If an action is already periodic, change frequency.

c.     Use pauses between impulses to provide additional action.

In particular, we decided to apply “replace a continuous action with a periodic one” and “use pauses between impulses to provide additional action” to solve the new design problems.

In the new design concept, the new component  consists of two induction coils. This new component  and magnetic bypass device () are mounted on magnetic anvil (). The electromagnetic anvil is positioned at 180 degrees relative to each other. When a voltage is applied to the induction coils, it produces a magnetic field. The force of the induction coil’s magnetic field attracts the magnetic hammer. By changing the voltage, the intensity of the magnetic field can be changed.

The function of impact torque in this new design concept is explained in Figures 5-2(a) ~ 5-2(c). In these figures, only a magnetic hammer and an electromagnetic anvil are illustrated to simplify the explanation. Referring to Figure 5-2 (a), a small clockwise rotation of the hammer (for example, 5 degrees) makes the hammer attracted magnetically towards the forward anvil. Under the torque of magnetic attraction, voltage is applied to the solenoid and the hammer accelerates towards the forward anvil. In Figure 5-2 (b), the shifting angle formed between the hammer and the anvil is equal to zero. At this angle, magnetic field lines emanating from the anvil travel through the ferromagnetic material of the corresponding hammer to complete the magnetic circuit. Accordingly, the hammer is at a stable equilibrium, being attracted strongly to the anvil. Note that the voltage is still applied to the solenoid during their action. Referring to Figure 5-2 (c), if the hammer rotates slightly in a clockwise direction (for example, 5 degrees), the hammer feels a pull towards the anvil due to magnetic attraction. If the electric current in the solenoid is briefly cut off, the magnetic attraction torque is reduced, establishing the magnetic impact condition.

Figure 5-2. The operation of the new design concept

Note that, the  (changing device) in U.S. Patent 6,918,449 comprises a micromotor, a worm gear and a pinion gear. In the new design concept,  consists of two induction coils. Therefore, the technological characteristics of  are different from those of , and the designing around is successful according to the doctrine of equivalents.

5.5.3 Discussions

The designer can try to find solutions for other design problems utilizing TRIZ. However, a good engineering design concept cannot be generated “automatically” by TRIZ. It still depends on the domain knowledge and experience of the designer. Moreover, transformation from a design matrix to an engineering design concept may fail because there may not be a feasible design corresponding to the new design matrix generated by the algorithm. For example, referring to the Section 5.4.1,

Design problem 2: “How to design a transformation  to achieve the function  (change magnetic flux) using component  (changing device)?”

This transformation fails, because the component  only performs the function “move magnetic bypass device”, it is unable to change magnetic flux by itself.