Supervision of transducers

• US 4,037,222 A
• Filed: 10/02/1975
• Issued: 07/19/1977
• Est. Priority Date: 10/02/1975
• Status: Expired due to Term

• Current Assignee: Elektrowatt AG Bellerivestrasse
• Original Assignee: Gulf & Western Manufacturing Company
• Inventors: Solomon, Elias E.
• Primary Examiner(s): Swann, III, Glen R.
• Application Number:
  US05/618,760
• Time in Patent Office: 656 Days
• Field of Search: 340/261, 340/409, 340/411, 340/214, 340/248 E, 340/248 R, 340/253 B, 340/253 Q, 340/52 F, 340/63, 340/224, 340/416, 179/175.1 A
• US Class Current: 181/139
• CPC Class Codes: G08B 29/10 Monitoring of the annunciator circuits
• CPC Class Codes: H04R 27/00 Public address systems circuits for preventing acoustic reaction H04R3/02; circuits for distributing signals to loudspeakers H04R3/12; monitoring or testing arrangements for public address systems H04R29/007; amplifiers H03F
• CPC Class Codes: H04R 29/007 for public address systems public address systems per se H04R27/00
• CPC Class Codes: H04R 3/00 Circuits for transducers , loudspeakers or microphones

Abstract

The operability of one or more audio speakers is monitored by continuously transmitting a non-audio signal on the lines connecting to the speakers and providing a vibration sensitive transducer such as a piezoelectric transducer which continuously picks up the signal. The output from the transducer couples to detection circuitry which may comprise an amplifier and gate or trigger circuit. The output of the detection circuitry couples either via the existing speaker lines or via a separate supervision line to an alarm device. When the speaker or speaker lines are inoperative the non-audio signal is not present and the gate circuit transmits an alarm signal to an alarm device. In one embodiment the detection circuitry is supplied power directly from the speaker lines via a rectifier means. In another embodiment the detection circuitry includes an oscillator, one associated with each speaker and each constructed to oscillate at a different frequency. With this arrangement the supervisory line may connect to a decoder for sensing the oscillator frequency when a fault occurs to thereby identify the malfunctioning speaker.

Claims

1. A system for monitoring the operation of at least one loud speaker means which has connected thereto an input signal line upon which audio signals are impressed for transmission to the speaker means, said system comprising;

means for coupling an alternating supervisory signal on the input signal line,

vibration sensitive transducer means directly responsive to mechanical deflections of the cone of the speaker and means for mounting the transducer means to the cone of the speaker means whereby the transducer means is responsive to the vibrations of the speaker means for providing an electrical alternating signal corresponding to the frequency of vibration of the speaker means,

and detection means coupled from the transducer means and responsive to the absence of the electrical alternating signal for generating an alarm condition indicative of the inoperability of the speaker means or input signal line.

2. A system as set forth in claim 1 wherein the transducer means includes a piezoelectric transducer.

3. A system as set forth in claim 1 including a plurality of speakers and like plurality of detection means.

4. A system as set forth in claim 3 wherein each said detection means comprises an amplifier means and gate means and further comprising a common alarm device to which all the gate means couples.

5. A system as set forth in claim 4 including a supervisory line coupled between detection means and alarm device so that the alarm device is disposed remote from the speakers.

6. A system as set forth in claim 1 including means coupled from the audio input line for providing operating power to the detection means.

7. A system as set forth in claim 6 wherein said means for providing operating power comprises an AC-to-DC converter means.

8. A system as set forth in claim 7 wherein said AC-to-DC converter means includes a rectifier means.

9. A system as set forth in claim 1 wherein the detection means includes a detection circuit, an alarm device and means coupling the detection circuit to the alarm device.

10. A system as set forth in claim 9 wherein the means coupling comprises a separate supervisory line independent of the audio input line.

11. A system as set forth in claim 9 wherein the means coupling comprises the audio input line.

12. A system as set forth in claim 3 including a common alarm means.

13. A system as set forth in claim 12 wherein said detection means includes an oscillator which is disabled when the speakers are operative and transmits a tone signal to the alarm means when one of the speakers malfunctions.

14. A system as set forth in claim 13 wherein an oscillator is associated with each speaker and each oscillator has a different operating frequency.

15. A system as set forth in claim 14 including means coupled from the oscillators for detection of the frequency of any oscillator that operates in response to a malfunctioning speaker.