Device with precision frequency stabilized audible alarm circuit

Patent metadata

Field	Value
Publication number	US-2017193762-A1
Application number	US-201514985080-A
Country	US
Kind code	A1
Filing date	Dec 30, 2015
Priority date	Dec 30, 2015
Publication date	Jul 6, 2017
Grant date	—

Abstract

Systems for ensuring an audible alarm circuit sounds at a minimum magnitude of loudness are provided. Different circuitry embodiments discussed herein are each capable of assisting the audible alarm circuit in maintaining a minimum loudness threshold. Audible alarm circuit operation optimization can be achieved using embodiments that fall within anyone of four general categories: compensation networks, direct drive, dynamic tuning, and microphone feedback based dynamic tuning. Use of such circuitry can increase production yields by compensating for manufacturing variations of alarm components and aging characteristics of the components.

First claim

What is claimed is:

1 . A device, comprising:
a three terminal piezo-electric buzzer; driver circuitry coupled to the piezo-electric buzzer and operative to drive operation of the piezo-electric buzzer, wherein the operation of the piezo-electric buzzer is characterized by a resonant frequency and buzzer phase; and compensation circuitry coupled to the piezo-electric buzzer and the driver circuitry to complete a circuit loop comprising the driver circuitry, the piezo-electric buzzer, and the compensation circuitry, the compensation circuitry operative to assist the driver circuitry in maintaining the piezo-electric buzzer in a stable oscillation by injecting additional phase into the circuit loop to supplement the buzzer phase and to enable the piezo-electric buzzer to operate at, or near, the resonant frequency.

2 . The device of claim 1 , wherein the compensation circuitry is selected from a plurality of different compensation circuitry configurations based on an optimization of the driver circuitry to achieve start up and stable oscillation over a band of frequencies that are part of production variation in the piezo-electric buzzer.

3 . The device of claim 1 , wherein the compensation circuitry comprises:
a 1-RC network; a 2-RC network; or a 4R2C network.

4 . The device of claim 1 , wherein the compensation circuitry comprises:
a resistor coupled to the piezo-electric buzzer and the driver circuitry; and a capacitor coupled to a node existing between the resistor and the piezo-electric buzzer.

5 . The device of claim 1 , wherein the compensation circuitry comprises
a first resistor coupled to the driver circuitry; a second resistor coupled to the first resistor and the piezo-electric buzzer; a first capacitor coupled to a node existing between the first and second resistors and ground; and a second capacitor coupled to a node existing between the second resistor and the piezo-electric buzzer and ground.

6 . The device of claim 1 , wherein the compensation circuitry comprises
a first resistor coupled to the driver circuitry; a second resistor coupled to the first resistor and the piezo-electric buzzer; a third resistor coupled to a node existing between the first and second resistors; a first capacitor coupled to the third resistor and ground; a fourth resistor coupled to a node existing between the second resistor and the piezo-electric buzzer; and a second capacitor coupled to the fourth resistor and ground.

7 . The device of claim 1 , wherein the compensation network further enables the piezo-electric buzzer to start oscillation.

8 . A device comprising:
a piezo-electric buzzer characterized as having a resonant frequency existing between first and second frequencies; driver circuitry coupled to the piezo-electric buzzer, the driver circuitry operative to provide a power signal to the piezo-electric buzzer; and a control unit coupled to the driver circuitry and operative to cause the driver circuitry to provide a frequency modulated power signal to the piezo-electric buzzer, wherein the frequency modulated power signal sweeps between the first and second frequencies such that when the modulated power signal is near the resonant frequency, the piezo-electric buzzer emits an audio output.

9 . The device of claim 8 , wherein the frequency modulated power signal is characterized by a rate and shape.

10 . The device of claim 9 , wherein the shape is a sinusoidal shape or a triangular shape.

11 . The device of claim 9 , wherein the rate defines a step change in the sweep between the first and second frequencies.

12 . The device of claim 9 , wherein the rate is selected based on a time interval between buzzer events and buzzer output power.

13 . The device of claim 8 , wherein the audible output comprises a shimmering audible output.

14 . The device of claim 8 , wherein the control unit can selectively cause the driver circuitry to apply one of a plurality of different frequency modulation schemes, wherein each of the different frequency modulation schemes causes the piezo-electric buzzer to emit a different audio output.

15 . The device of claim 8 , wherein the piezo-electric buzzer characterized as having a first resonant frequency existing between first and second frequencies and a second resonant frequency existing at a third frequency, and wherein the control unit is operative to provide a provide a frequency modulation signal that causes the piezo-electric buzzer to emit audio energy at the first and second resonant frequencies.

16 . A maximum resonance driving device comprising:
an electroacoustic transducer; driver circuitry coupled to the transducer, the driver circuitry operative to drive operation of the transducer; control circuitry coupled to the driver circuitry, the control circuitry operative to provide a signal that can vary output of the driver circuitry; and sense circuitry coupled to an output of the driver circuitry and to the control circuitry, the sense circuitry operative to:
monitor the output of the driver circuitry; and
instruct the control circuitry to change a value of the signal based on the monitored output such that the transducer emits an audio signal having at least a minimum magnitude.

17 . The device of claim 16 , wherein the driver circuitry, the control circuitry, and the sense circuitry operate together to maximize the magnitude of the audio output of the transducer.

18 . The device of claim 16 , wherein the sense circuitry instructs the control circuitry in real-time.

19 . The device of claim 16 , wherein the control circuitry comprises an adjustable network that can vary output of the driver circuitry, and wherein the sense circuitry is operative to instruct the control circuitry to change a value of the adjustable network based on the monitored output such that the transducer emits an audio signal having a maximum magnitude.

20 . A device comprising:
an electroacoustic transducer; driver circuitry coupled to the transducer, the driver circuitry operative to drive operation of the transducer; control circuitry coupled to the driver circuitry, the control circuitry operative to provide a signal that can vary output of the driver circuitry; a microphone; sense circuitry coupled to the control circuitry and the microphone, the sense circuitry operative to:
monitor an output of the microphone; and
instruct the control circuitry to change a value of its adjustable network based on the monitored output of the microphone such that the transducer emits an audio signal having at least a minimum magnitude.

21 . The device of claim 20 , wherein the sense circuitry instructs the control circuitry in real-time.

22 . The device of claim 20 , wherein the transducer is coupled to the control circuitry, and wherein the sense circuitry permanently configures the adjustable network to use as a phase shift network that supplements a phase of the transducer to enable stable operation of the transducer.

23 . The device of claim 20 , wherein the control circuitry comprises an adjustable network that can vary output of the driver circuitry, and wherein the sense circuitry instructs the control circuitry to change a value of its adjustable network based on the monitored output of the microphone such that the transducer emits an audio signal having a maximum magnitude.

Assignees

• Google Inc

Inventors

• Warren Daniel Adam
• Heyl Lawrence Frederick
• Ho Dietrich
• Aina Morakinyo John
• Smith Ian C
• Saperstein William
• Vadathavoor Bhaskar

Classifications

• H04R17/00

  Piezoelectric transducers; Electrostrictive transducers (piezoelectric or electrostrictive elements in general H10N30/00; details of piezoelectric or electrostrictive motors, generators or positioners {H10N30/00}) · CPC title

• G08B3/10 Primary

  using electric transmission; using electromagnetic transmission · CPC title

• G08B29/18

  Prevention or correction of operating errors (G08B29/02, G08B29/12 take precedence) · CPC title

• H04R3/00

  Circuits for transducers (arrangements for producing a reverberation or echo sound G10K15/08; amplifiers H03F) · CPC title

• H04R2430/01

  Aspects of volume control, not necessarily automatic, in sound systems · CPC title