Tap sensitive alarm clock

摘要

A tap sensitive alarm clock has a housing (20), a vibration sensor (22) mechanically coupled to the housing for receiving a shock due to a user tapping the housing, and a control circuit (24) coupled to the vibration sensor for controlling a function of the alarm clock. An audio unit (26) is coupled to an audio circuit (25) for generating sound, e.g. a loudspeaker in an alarm clock or a wake up light. To avoid interference of the sound and the vibration sensor, the alarm clock is provided with a filter (23) coupled to the vibration sensor and the control circuit. The filter has a filter curve matched to block frequencies occurring in the sound. Advantageously it is avoided that the sound frequencies trigger the function, while the sensor is sensitive to other frequencies up to the frequency range of the sound for reliably detecting the tapping.

主权项

1. An apparatus comprising a tap-sensitive alarm clock including;
a housing; a vibration sensor mechanically coupled to the housing for receiving a shock due to a user tapping on the housing, said shock including components in a first frequency range; a control circuit coupled to the vibration sensor for controlling a function of the alarm clock; an audio unit coupled to an audio circuit for generating sound including components in a second frequency range that overlaps an upper end of the first frequency range, said second frequency range including frequencies in said upper end of the first frequency range and frequencies higher than the first frequency range; and an adjustable a filter coupled to the vibration sensor and the control circuit, said filter being adjusted to limit passage from the vibration sensor to the control circuit of only the shock components having frequencies in the first frequency range that are not also in the second frequency range.