  The patent database is often used in searches of inspirational stimuli for
innovative design opportunities because of its large size, extensive variety
and rich design information in patent documents. However, most patent mining
research only focuses on textual information and ignores visual information.
Herein, we propose a convolutional neural network (CNN)-based patent image
retrieval method. The core of this approach is a novel neural network
architecture named Dual-VGG that is aimed to accomplish two tasks: visual
material type prediction and international patent classification (IPC) class
label prediction. In turn, the trained neural network provides the deep
features in the image embedding vectors that can be utilized for patent image
retrieval and visual mapping. The accuracy of both training tasks and patent
image embedding space are evaluated to show the performance of our model. This
approach is also illustrated in a case study of robot arm design retrieval.
Compared to traditional keyword-based searching and Google image searching, the
proposed method discovers more useful visual information for engineering
design.
