COMBINATION VIBRATOR AND ELECTRICAL INDUCTOR DC TO DC/AC CONVERTER
Original Publication Date: 1995-Nov-01
Included in the Prior Art Database: 2002-Apr-04
The vibrator or silent alert used in pagers is a DC motor with a weight distribution that is unbal- anced about the axis of rotation. When a message is received the motor is connected to the battery and the unbalanced weight results in the entire pager vibrating, silently alerting the user ofa message recep- tion. Since the motor is idle almost all ofthe operat- ing time, it seems like a very good candidate for utilization of its elements for other functions within the product. There are typically three inductors associated with the armature of the motor, which is designed to have one connected between the two motor terminals at all rotation angles. In addition, the inductance value and losses are consistent with those used in DC to DC or AC converter applica- tions. This paper discusses the application of the motor inductance for a DC to AC voltage multiplier for a piezo alert tone element, and a DC voltage multiplier for an LED indicator or back lighting. These functions are compatible with the intended vibrator function and could be utilized at the same time ifdesired, see Figure 1.