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Theory of Inventive Problem Solving (TRIZ) 295

9.3 TRIZ Problem-Solving Process
TRIZ has a four-step problem-solving process: (1) problem definition,
(2) problem classification and problem tool selection, (3) problem
solution, and (4) solution evaluation. We shall describe each step in
detail.

9.3.1 Problem definition
Problem definition is a very important step. The quality of the solution is
highly dependent on problem definition.
The problem definition starts with several questions:

1. What is the problem?
2. What is the scope of the project?
3. What subsystem, system, and components are involved?
4. Do we have a current solution, and why is the current solution not
good?

These are common questions to be asked in any engineering project.
By answering these questions, we are able to define the scope of the
project and focus on the right problem area.
Besides answering these common questions, several TRIZ methods
are also very helpful in the problem definition stage.

Functional modeling and functional analysis. After identifying the proj-
ect scope, it is very helpful to establish the functional model of the sub-
system involved in this project. Functional modeling and analysis enables
us to see the problem more clearly and precisely. We will recall the
toothbrush example to illustrate how functional analysis can help the
problem definition.

Example 9.4. Toothbrush Problem Revisited Assume that we are a tooth-
brush manufacturer, and the current regular toothbrush is not satisfactory
in performance, that is, teeth cannot be adequately cleaned. We can first
draw the following functional diagram:

Brush
Toothbrush Teeth
Mech.

By analyzing the functional diagram, we may come up with the following
possibilities:
1. The current lack of performance may be caused by “inadequate action,”
that is, the actual functional diagram is the following: