Hybrid piezoelectric device / radio frequency antenna

• US 9,660,324 B2
• Filed: 10/12/2015
• Issued: 05/23/2017
• Est. Priority Date: 03/05/2014
• Status: Active Grant

• Current Assignee: Fitbit, Inc. (Alphabet Inc.)
• Original Assignee: Fitbit, Inc. (Alphabet Inc.)
• Inventors: Baringer, William B.
• Primary Examiner(s): Nguyen, Hoang
• Application Number:
  US14/880,706
• Publication Number:
  US 20160036119A1
• Time in Patent Office: 589 Days
• CPC Class Codes: A61B 5/0002 Remote monitoring of patients using telemetry, e.g. transmission of vital signals via a communication network A61B5/07 takes precedence; transmission systems for measured values G08C; transmission H04B; transmission of digital information H04L; wireless communication networks H04W
• CPC Class Codes: A61B 5/02416 using photoplethysmograph signals, e.g. generated by infrared radiation A61B5/14552 takes precedence
• CPC Class Codes: A61B 5/02427 Details of sensor
• CPC Class Codes: A61B 5/02433 for infrared radiation
• CPC Class Codes: A61B 5/02438 with portable devices, e.g. worn by the patient
• CPC Class Codes: A61B 5/1123 Discriminating type of movement, e.g. walking or running A61B5/1116, A61B5/112 take precedence
• CPC Class Codes: A61B 5/4812 Detecting sleep stages or cycles
• CPC Class Codes: B06B 1/0644 using a single piezoelectric element B06B1/0688 takes precedence
• CPC Class Codes: H01Q 1/22 by structural association with other equipment or articles
• CPC Class Codes: H01Q 1/273 Adaptation for carrying or wearing by persons or animals
• CPC Class Codes: H01Q 1/48 Earthing means; Earth screens; Counterpoises
• CPC Class Codes: H01Q 21/28 Combinations of substantially independent non-interacting antenna units or systems multiple beam H01Q25/00
• CPC Class Codes: H01Q 9/0407 Substantially flat resonant element parallel to ground plane, e.g. patch antenna dipole H01Q9/285; monopole H01Q9/40
• CPC Class Codes: H01Q 9/0421 with a shorting wall or a shorting pin at one end of the element H01Q9/0414 takes precedence
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04W 4/027 using movement velocity, acceleration information
• CPC Class Codes: H10N 30/00 Piezoelectric or electrostrictive devices integrated devices or assemblies of multiple devices H10N39/00
• CPC Class Codes: H10N 30/03 Assembling devices that include piezoelectric or electrostrictive parts
• CPC Class Codes: H10N 30/072 by laminating or bonding of piezoelectric or electrostrictive bodies
• CPC Class Codes: H10N 30/20 with electrical input and mechanical output, e.g. functioning as actuators or vibrators
• CPC Class Codes: Y10T 29/42 : Piezoelectric device making
• CPC Class Codes: Y10T 29/49016 : Antenna or wave energy "plumbing" making

Abstract

A hybrid antenna including a piezoelectric device and an RF radiator. The hybrid antenna is capable of providing both RF and piezoelectric device functionality, e.g., radio frequency transmission/reception capabilities for radio frequency devices as well as sound-producing and/or energy-scavenging functionality via the piezoelectric device. The piezoelectric device may be in conductive contact with the RF radiator or may not be in conductive contact with the RF radiator.

Claims

1. An apparatus comprising:

a ground plane;

a radio-frequency radiator, the radiator offset from the ground plane in a direction substantially normal to the ground plane by a first distance;

a feed post conductively connected to the radiator; and

a piezoelectric assembly offset from the ground plane in a direction substantially normal to the ground plane by a second distance, the piezoelectric assembly configured to couple inductively with the radiator and being separated from the radiator by at least a housing structure of the apparatus, wherein the piezoelectric assembly, the radiator, the ground plane, and the feed post together form an antenna configured to produce electro-magnetic radio-frequency signals and receive electro-magnetic radio-frequency signals.

2. The apparatus of claim 1, wherein:

the piezoelectric assembly comprises a piezoelectric material, a first electrode, and a second electrode,

the piezoelectric material is positioned between the first electrode and the second electrode, and

the piezoelectric assembly is configured to produce a piezoelectric effect and configured to be powered through mutual inductive coupling with the radiator.

3. The apparatus of claim 2, wherein the piezoelectric material includes one or more compounds selected from the group consisting of:

gallium orthophosphate, langasite, barium titanate, lead titanate, lead zirconate titanate, lithium niobate, lithium tantalate, sodium tungstate, zinc oxide, Ba2NaNb5O5, Pb2KNb5O15, sodium potassium niobate, bismuth ferrite, sodium niobate, bismuth titanate, sodium bismuth titanate, and polyvinylidene fluoride.

4. The apparatus of claim 1, further comprising a current-blocking component, wherein:

the current-blocking component is configured to at least substantially block radio-frequency current from reaching the piezoelectric assembly; and

the current-blocking component is in conductive contact with the feed post.

5. The apparatus of claim 1, wherein the piezoelectric assembly at least partially overlaps the ground plane.

6. The apparatus of claim 1, wherein the apparatus further comprises an insulating layer that is interposed between the radiator and the piezoelectric assembly.

7. The apparatus of claim 1, further comprising:

a first housing portion; and

a second housing portion, wherein;

the radiator is supported by the first housing portion,

the piezoelectric assembly is supported by the second housing portion, and

the first housing portion is mated to the second housing portion.

8. The apparatus of claim 7, wherein the ground plane is provided by a structure located on an opposite side of the first housing portion from the radiator.

9. The apparatus of claim 8, wherein the structure is selected from the group consisting of:

a printed circuit board, a flexible circuit board, a metal plate contained within the apparatus, and a metal plate at least partially providing an exterior surface of the apparatus.

10. The apparatus of claim 1, further comprising:

a plastic carrier; and

a substrate with a printed circuit, wherein;

the radiator is supported by the plastic carrier,

the plastic carrier is supported by the substrate with the printed circuit,

the substrate with the printed circuit acts as the ground plane, and

the piezoelectric assembly is also supported by the plastic carrier.

11. The apparatus of claim 1, wherein the housing structure has a first surface and a second surface, wherein:

the first surface and the second surface are nominally on opposing sides of a portion of the housing structure,

the radiator is formed by a metallization layer deposited on the first surface, and

the piezoelectric assembly is located on or adjacent to the second surface such that the second surface is interposed between the first surface and the piezoelectric assembly.

12. The apparatus of claim 1, wherein the housing structure proximate to the radiator is less than or equal to 2 mm, and wherein the first distance is between about 0.5 mm and 10 mm.

13. The apparatus of claim 1, wherein the piezoelectric assembly is substantially circular or substantially rectangular in overall shape.

14. The apparatus of claim 13, wherein the radiator is substantially circular in overall shape and:

the radiator has an average diameter of between 5 mm and 25 mm; and

the piezoelectric assembly has an average diameter of between 5 mm and 25 mm.

15. The apparatus of claim 1, wherein the radiator is O-shaped, C-shaped, L-shaped, U-shaped, or rectangular-shaped.

16. The apparatus of claim 1, wherein the radiator is configured to couple inductively and directly with the piezoelectric assembly.

17. The apparatus of claim 1, wherein the ground plane is a non-planar surface.

18. The apparatus of claim 1, further comprising:

a first housing portion of a wearable device; and

a second housing portion of the wearable device and mated to the first housing portion, wherein the radiator is supported in a recess between the first housing portion and the second housing portion, the recess being positioned outside a display cover of the wearable device.

19. The apparatus of claim 1, further comprising a shorting post conductively connecting the radiator to the ground plane, wherein:

the piezoelectric assembly, the radiator, the ground plane, the shorting post, and the feed post form an antenna configured to produce and receive electric radio-frequency signals in a Bluetooth-compatible frequency band.

20. The apparatus of claim 1, further comprising a shorting post conductively connecting the radiator to the ground plane, wherein:

the piezoelectric assembly, the radiator, the ground plane, the shorting post, and the feed post form an antenna configured to produce and receive electric radio-frequency signals in a GPS-compatible frequency band.

21. The apparatus of claim 1, wherein the radiator is interposed between the piezoelectric assembly and the ground plane.

22. The apparatus of claim 1, further comprising a first electrical conductor and a second electrical conductor, wherein the piezoelectric assembly comprises a piezoelectric material between a first electrode and a second electrode, the first electrical conductor connected to the first electrode and the second electrical conductor connected to the second electrode.

23. The apparatus of claim 1, wherein the piezoelectric assembly is configured to produce a sound or range of sounds.

24. The apparatus of claim 1, further comprising a battery, wherein the piezoelectric assembly is configured to scavenge energy by converting vibrations induced in the piezoelectric assembly into an electrical charge and output the electrical charge to the battery.

25. The apparatus of claim 1, wherein the antenna is a planar inverted-F antenna (PIFA).

26. A method comprising:

a) providing a radio-frequency radiator, a ground plane, and a feed post, wherein the radiator is separated from the ground plane by a first distance, and wherein the feed post is conductively connected to the radiator;

b) mounting the radiator to a first surface of a first housing component;

c) providing a piezoelectric assembly; and

d) placing the piezoelectric assembly such that the piezoelectric assembly is offset from the ground plane in a direction substantially normal to the ground plane by a second distance, and is configured to couple inductively with the radiator and is separated from the radiator by at least a housing structure but sufficiently close to the radiator to be coupled with the radiator, wherein the piezoelectric assembly, the radiator, the ground plane, and the feed post together form an antenna configured to produce electro-magnetic radio-frequency signals and receive electro-magnetic radio-frequency signals.

27. The method of claim 26, wherein the radiator is interposed between the piezoelectric assembly and the ground plane, the piezeoelectric assembly configured to be powered through mutual inductive coupling with the radiator.

28. The method of claim 26, further comprising:

providing a second housing component;

bonding the piezoelectric assembly to a second surface of the second housing component; and

mating the second housing component to the first housing component, wherein the piezoelectric assembly is bonded to the second surface in a location that causes (d) to be concurrently performed when the second housing component is mated to the first housing component.

29. The method of claim 28, wherein a recess between the first housing component and the second housing component is defined when the first housing component and the second housing component are mated together, wherein the radiator is supported in the recess.