Producing distributed vibration by a single piezoelectric ceramics for a small tactile stimulator

A small tactile display that can be attached to a mobile terminal device or a handheld game controller will enhance user experience in virtual worlds. This paper proposes an ultrasonic vibrator which has a compact mechanism to produce vibratory stimulation on human skin using a pin array driven by a single piezoelectric actuator. Amplitude modulations of the ultrasonic vibration can generate tactile sensations even if a finger is fixed on the vibrator. To generate enough stimulation to deform the skin, resonance of the piezoelectric actuator was designed. We proposed a new mechanical design method to arrange arbitrary distributions of vibration for the pin array using the principle of a dynamic vibration absorber. Detailed designs were conducted by finite element analysis. We successfully designed a smart vibrator which had a size of 17 times 17 times 3.65 mm and a weight of about 4 g. The vibrator could mount on the joystick of the PlayStation2 controller. Trial experiments of tactile presentation showed that the prototype vibrator could generate vibratory feelings in the range of 30 - 50 Hz and 200 - 300 Hz. In addition, stimulation corresponding to joystick operation generated some rubbing-like sensation.