This paper proposes CLaP, a novel algorithm for processing massive amounts of high-resolution unannotated time series (TS) data generated from machines, smart devices, and environments. To overcome the predictive performance limitations of existing unsupervised learning-based time series state detection (TSSD) algorithms, CLaP utilizes self-supervised learning techniques to detect whether data segments originate from the same state. It quantifies confusion between segment labels and merges the labels of highly confused segments to improve overall classification performance. Experimental results using 405 time series data sets from five benchmarks demonstrate that CLaP outperforms six existing state-of-the-art algorithms in accuracy and efficiency, achieving an optimal trade-off between accuracy and execution time while demonstrating scalability to large-scale time series data. A Python-based implementation of CLaP is also provided.