Ultrasonic MEMS transmitter

摘要

Ultrasonic transmitters that can be used for ranging in mobile devices are disclosed. In some examples, an ultrasonic transmitter device can be configured to transmit ultrasonic signals in multiple frequency bands. The transmitter can include multiple sets of ultrasonic transmitters, each capable of transmitting in a different frequency band. In other examples, frequency-adjustable ultrasonic transmitters can be used. The transmitters can be configured to change one or more of a length, mass, or tension of a membrane to change a resonant frequency of the membrane. In some examples, the transmitter can include a non-uniformly shaped membrane capable of vibrating at more than one resonant frequency. The ultrasonic transmitters can be included within a housing configured to control the flow of air within and out of the housing. The transmitter membrane can further be formed on a patterned substrate configured to increase the sound pressure levels produced by the transmitter.

主权项

1. A transmitter comprising:
a drum; a membrane coupled to the drum; a first electrode coupled to the drum; a second electrode coupled to the membrane; and a plurality of posts disposed within the drum, wherein the plurality of posts have non-uniform heights such that: while the membrane is in a first configuration, a first post of the plurality of posts causes the membrane to have a first length; and while the membrane is in a second configuration, a second post of the plurality of posts causes the membrane to have a second length, different from the first length; wherein the membrane is configured to transmit an ultrasonic signal at a first frequency, corresponding to the first length, when a signal having a first DC voltage component is applied to the first electrode, and wherein the membrane is configured to transmit an ultrasonic signal at a second frequency, corresponding to the second length, when a signal having a second DC voltage component is applied to the first electrode.