In the early 1950s, Ibuka traveled in Asia and heard about Bell Labs' invention of the transistor. He convinced Bell to license the transistor technology to his Japanese company. While most Japanese companies were researching the transistor for its military applications, Ibuka and Morita looked to apply it to communications. Although the American companies Regency Electronics and Texas Instruments built the first transistor radio as joint venture, it was Ibuka's company that made them commercially successful for the first time.
In August 1955, Tokyo Tsushin Kogyo released the Sony TR-55, Japan's first commercially produced transistor radio. They followed up in December of the same year by releasing the Sony TR-72, a product that won favor both within Japan and in export markets, including Canada, Australia, the Netherlands and Germany. Featuring six transistors, push-pull output and greatly improved sound quality, the TR-72 continued to be a popular seller into the early sixties.
According to wikipedia