To realize incremental product innovation, the key problems of existing products need to be identified and solved with feasible innovation schemes. This study examines the generation process of innovation schemes by integrating Quality Function Deployment (QFD) and the Theory of Inventive Problem Solving (TRIZ). This study has the following advantages: first, this study proposes new rules for distinguishing physical conflicts with technical conflicts and the method for calculating conflict importance after building House of Quality (HoQ) in QFD. Second, an improved integrated model of QFD and TRIZ is constructed, which generates innovation schemes by solving not only the conflicts between technical characteristics but also the problems of product parts. Third, the uncertainty and subjectivity of the data provided by decision-makers in the evaluation process of innovation schemes are processed by interval grey numbers. Moreover, a cone model is built to make the evaluation results more reliable. Last, a case study of water purifiers is conducted to illustrate the validity of the generation process of incremental product innovation schemes.