In a signal generation circuit for a compound acoustic actuator that generates a sound and a vibration in response to a frequency of a signal input to the compound acoustic actuator, the signal generation circuit comprising a plurality of signal data stored in a memory to generate a plurality of signals having mutually different frequencies, the plurality of signals at least including a signal, a frequency of which is equal to a resonant frequency causing the compound acoustic actuator to generate the vibration, a synthesizing means to synthesize a plurality of drive signals in accordance with the plurality of signal data so as to cause the compound acoustic actuator to generate the vibration, and a sweeping means to sweep the plurality of drive signals, repeatedly.
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
This application is a division of application Ser. No. 09/972,923, filed Oct. 10, 2001, now U.S. Pat. No. 6,617,966, and based on Japanese Patent Application No. 2000-312176, filed Oct. 12, 2000, by Chiemi Takahashi. This application claims only subject matter disclosed in the parent application and therefore presents no new matter.
A mobile wireless communication device has a speaker that functions as a vibration alert in addition to an audio output device. The speaker is selected from a group of speakers having variation in mechanical vibration resonant frequency. A drive signal sweeps back and forth across a sweep frequency range including the varient speaker mechanical vibration resonant frequencies. The drive signal drives the speaker causing it to vibrate at the mechanical vibration resonant frequency and in turn causing the mobile wireless communication device to vibrate, thereby alerting the user. In this manner, the same drive signal can be used to vibrate each speaker at the speaker's mechanical vibration resonant frequency despite the variation in mechanical vibration resonant frequencies among the group of speakers.
