Effect of sheet-metal thickness and hardness on the life cycle and sliding force of a novel ultraslim spring unit for a semi-automatic sliding mechanism used in IT devices

Abstract

Great strides made in the industries manufacturing components for IT devices have facilitated the development of cellular phones that are either similar in size or smaller than previously existing phones. In addition, the functions carried out by devices such as MP3 players, digital cameras, and GPS devices are now being incorporated into cellular phone, the quintessential IT device. However, there are limitations on the extent to which the sizes of the components can be reduced due to technical reasons pertaining to mechanical and/or electrical properties, the manufacturing process, and the structure of the assembly. In addition, more emphasis than ever is being placed on the design of a cellular phone as it has come to be regarded as a necessity; thus, like an accessory, it needs to be stylish, highly mobile, and portable, regardless of advances in technology. To develop phones that meet these requirements, the thickness and degree of design freedom have to be reduced and improved, respectively. With this in mind, we propose a novel spring unit for the slide mechanism of a cellular phone as a practical alternative not only for maintaining the mobility and portability of the phone, but also for increasing competitiveness as this component helps to reduce the thickness of the phone. In addition, it provides a degree of freedom that allows other hardware components in the phone to be placed and adjusted more freely than conventional spring units built for the same purpose. Experiments conducted indicate that the life cycles and sliding forces of our proposed spring can be easily set by merely controlling the thickness and hardness of the sheet metal plate used for fabricating the spring. Furthermore, our proposed spring can be used to further reduce the thickness of the existing IT devices while preserving their performance and reliability. We believe that our etching process using heat-treated sheet metal can be widely applied to fabricate springs for various applications that require minimized thickness.