Handheld device having ultrasonic transducer for axial transmission of acoustic signals
View Patent ↗A handheld stylus having an elongated housing, a writing and drawing implement disposed within the housing and including a tip extending through an opening at an end of the housing where ultrasonic waves radiate therefrom and are used for determining a position of the stylus; and at least one ultrasonic transducer disposed within the housing. The transducer may be a cylindrical piezoelectric transducer having a holder and a cylindrical piezoelectric film spanning between at least two spaced apart cylindrical surfaces of the holder, or a flat transducer having a diaphragm, and a piezoelectric material disposed on a surface of the diaphragm.
1. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film; and
an inner electrode segment disposed on an inner surface of the film;
a cover spaced from the outer surface of the film, the cover including a flange restricting propagation of the radiating acoustic energy along a propagation path defined along an exterior of the film;
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to an excitation voltage applied to the film via the electrode segments.
2. The transducer of claim 1 , further comprising a reflector disposed at an end thereof for redirecting the radiating acoustic energy in an opposite direction.
3. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film;
an inner electrode segment disposed on an inner surface of the film;
a reflector disposed at an end thereof for redirecting the radiating acoustic energy in an opposite direction;
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to an excitation voltage applied to the film via the electrode segments.
4. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film; and
an inner electrode segment disposed on an inner surface of the film,
wherein: the at least two spaced apart cylindrical surfaces comprising a plurality of spaced apart cylindrical surfaces;
the film spanning between at least two pairs of the plurality of spaced apart cylindrical surfaces of the holder;
the outer electrode segment comprising a plurality of outer electrode segments; and
the inner electrode segment comprising a plurality of inner electrode segments; and
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to an excitation voltage applied to the film via the electrode segments.
5. The transducer of claim 4 , further comprising a cover spaced from the outer surface of the film, the cover including a flange restricting propagation of the radiating acoustic energy along a propagation path defined along an exterior of the film.
6. The transducer of claim 5 , further comprising a reflector disposed at an end thereof for redirecting the radiating acoustic energy in an opposite direction.
7. The transducer of claim 6 , further comprising a reflector disposed at an end thereof for redirecting the radiating acoustic energy in an opposite direction.
8. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film;
an inner electrode segment disposed on an inner surface of the film;
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to an excitation voltage applied to the
film via the electrode segments and wherein the excitation voltage has a frequency which has a wavelength in a propagation medium, and a width of each of the electrode segments is about half of the wavelength.
9. The transducer of claim 8 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer.
10. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film;
an inner electrode segment disposed on an inner surface of the film;
a drive circuit for sequentially applying an excitation voltage to the electrode segments of the transducer; and
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to the excitation voltage applied to the film via the electrode segments.
11. The transducer of claim 4 , wherein the excitation voltage has a frequency which has a wavelength in a propagation medium, wherein about half of the wavelength is more than a width of each of the electrode segments.
12. The transducer of claim 11 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer.
13. The transducer of claim 4 , further comprising a drive circuit for sequentially applying the excitation voltage to the electrode segments of the transducer.
14. The transducer of claim 4 , wherein the holder restricts propagation of the radiating acoustic energy along a propagation path defined within an interior of the film.
15. The transducer according to claim 4 , wherein the electrode segments have a center to center distance of one-half of a wavelength and the electrode segments are driven such that every other one is driven in-phase with every adjacent electrode segment in opposite phase drive.
16. An ultrasonic transducer comprising:
a holder having at least two spaced apart cylindrical surfaces;
a cylindrical piezoelectric film spanning between the at least two spaced apart cylindrical surfaces of the holder;
an outer electrode segment disposed on an outer surface of the film; and
an inner electrode segment disposed on an inner surface of the film;
wherein the transducer radiates acoustic energy substantially along a longitudinal axis thereof in response to an excitation voltage applied to the film via the electrode segments and wherein the excitation voltage has a frequency which has a wavelength in a propagation medium, and a width of each of the electrode segments is about 10 to 20 percent greater that one-half the wavelength.