Abstract: The disclosure is directed to a wearable device that is configured to secure itself based on signals received from a pulse sensor. According to one implementation, the pulse sensor includes a light source (e.g., a light-emitting diode) and a photo sensor. The light source, under the control of a processor, shines light having a particular wavelength (e.g., green or infrared). The photo sensor generates signals based on light that it senses. For example, when the light from the light source reflects off a person's skin, then the photo sensor will generate signals based on the reflected light that the photo sensor detects. In this manner, the wearable device can accurately determine whether it is being worn by a user (e.g., by taking a photoplethysmogram) and, when necessary, secure the wearable electronic device.

Abstract: The disclosure is directed to a wearable device that is configured to secure itself based on signals received from a pulse sensor. According to one implementation, the pulse sensor includes a light source (e.g., a light-emitting diode) and a photo sensor. The light source, under the control of a processor, shines light having a particular wavelength (e.g., green or infrared). The photo sensor generates signals based on light that it senses. For example, when the light from the light source reflects off a person's skin, then the photo sensor will generate signals based on the reflected light that the photo sensor detects. In this manner, the wearable device can accurately determine whether it is being worn by a user (e.g., by taking a photoplethysmogram) and, when necessary, secure the wearable electronic device.

Abstract: A circuit (800) for controlling at least one piezoelectric actuator (142) includes a piezoelectric drive circuit (802) that generates unidirectional voltage drive signal, also referred to as Vout, at node (804). The piezoelectric actuator drive circuit (802) includes a boost switcher circuit or charging circuit (806), a buck switcher circuit or pulsed current sink discharge circuit (808) and a control signal generating circuit (810) that receives an input control signal (812) from, for example, a keyboard processor or other suitable processor (604) indicating that the device has requested generation of haptic feedback utilizing the piezoelectric actuator (142). The control signal generating circuit (810) provides at least two pulse-with-modulated control signals, one to control the charging circuit and one to control the discharging circuit to produce the unidirectional voltage drive signal, that in one example is a raised cosine drive signal (904).

Abstract: A circuit (800) for controlling at least one piezoelectric actuator (142) includes a piezoelectric drive circuit (802) that generates unidirectional voltage drive signal, also referred to as Vout, at node (804). The piezoelectric actuator drive circuit (802) includes a boost switcher circuit or charging circuit (806), a buck switcher circuit or pulsed current sink discharge circuit (808) and a control signal generating circuit (810) that receives an input control signal (812) from, for example, a keyboard processor or other suitable processor (604) indicating that the device has requested generation of haptic feedback utilizing the piezoelectric actuator (142). The control signal generating circuit (810) provides at least two pulse-with-modulated control signals, one to control the charging circuit and one to control the discharging circuit to produce the unidirectional voltage drive signal, that in one example is a raised cosine drive signal (904).