Patent Application
20110228634
As detailed in U.S. Pat. No. 7,369,458, the entire teachings of which are incorporated herein by reference, sonar devices have widespread use in sport fishing, navigation, scuba diving, as well as any number of other recreational or commercial activities. A sonar system often includes a sonar unit and a transducer. The sonar unit includes a display for providing information to the operator. The transducer is often mounted under the waterline and is responsible for generating a sonic pulse (or sound pulse) and receiving echoes from objects in the water, from the bottom surface, or both.
The sonar unit often includes the electronic circuitry that produces a sonar pulse consisting of several cycles of a sonic signal at a fairly high output power. This pulse is delivered to the transducer usually via a shielded twisted pair cable. After transmission of the pulse, the transducer is typically used to “listen” for echoes. Received echoes produce very small signals, on the order of a few milli-volts, which are sent via a transmission line to a receiver circuitry in the sonar unit. In the sonar unit, the received echoes are amplified, filtered, and analyzed.
Acoustic transducers, especially broadband, communication, and weapons system transducers are prone to self-heating due to the high power and long duty cycles.
An example embodiment of the present invention relates to a method and corresponding apparatus for controlling the temperature of an acoustic transducer. The example embodiment monitors the temperature of the acoustic transducer and controls the temperature as a function of adjusting one or more characteristics of the acoustic transducer.
Another embodiment of the present invention relates to a method and corresponding apparatus that obtains temperature information from an acoustic transducer. The example embodiment compares the obtained temperature information against a database of known temperature values associated with transducer characteristics and controls the temperature of the acoustic transducer as a function of adjusting the transducer characteristics.
Yet another embodiment of the present invention relates to a method and corresponding apparatus that obtains characteristics information including information regarding at least one of impedance, voltage, current, phase angle, or temperature of internal transducer components from an acoustic transducer. The example embodiment compares the characteristics information against a database of known temperature values associated with transducer characteristics information values and adjusts the temperature as a function of adjusting the transducer characteristics information to reduce self-heating of the transducer.
The characteristic information of the transducer may include drive waveform of the transducer.
The foregoing will be apparent from the following more particular description of example embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views.
The drawings are not necessarily to scale, emphasis instead being placed upon illustrating embodiments of the present invention.
a-8c illustrate high-level functional diagrams of example embodiments for monitoring temperature in a transducer.
A description of example embodiments of the invention follows.
A Transducer ID system (XducerID®, available from Airmar Technology Corp. Milford, N.H.) includes an echosounder 110, a transducer 120 (e.g., an acoustic transducer), and a communication bus (communication cable) 130. The transducer 120 may contain one or more piezoelectric elements 123 having varying characteristics that are contained within a housing 122 of the transducer assembly 120 that can be adapted to be mounted to a marine vessel 105. The echosounder 110 contains electronic circuitry for driving transducer element 123 (such as a piezoelectric element) within the transducer 120 to transmit a sonic acoustic pulse and for amplifying and filtering received echoes from the piezoelectric elements 123. Certain embodiments may include using other transducers known in the art such as magnetostriction transducers or electrodynamic transducers together with the transducer ID system.
The transducer 120 may further include a non-volatile memory device (not shown) within a microprocessor, microcontroller, or state machine that contains the characteristic information of the transducer. The microcontroller, upon system initialization or power-up, may communicate the characteristic information of the transducer from the memory device to the echosounder 110 via the communication bus 130.
The communication bus 130 may be a single conductor (wire) plus a ground return in the transducer cable, a multi wire bus, or a fiber optic cable. In a Transducer ID system 100, the echosounder 110 and the transducer both include a certain amount of circuitry. The echosounder 110 provides power to the circuitry in the transducer 120. In certain embodiments, the communication bus 130 may provide power to the memory device and the microcontroller embedded in the transducer and/or allow bidirectional serial communication (e.g., half duplex) between the echosounder 110 and the transducer 120. A cable shield may be used as the ground return of the communication bus 130.
In certain embodiments, the echosounder 110 and the transducer 120 may communicate via a wireless connection.
In certain embodiments, the transducer 120 may communicate with the echosounder 110 via an optional wireless communications link (not shown). Generally, any form of communications available in the art may be used to communicate between the transducer and the echo sounder.
The transducer 120 may further include a temperature sensor such as a thermistor. In certain embodiments, the transducer 120 may include multiple thermistors (e.g., up to three thermistors) for monitoring transducer 120, water temperature, and/or water temperature in transducer housing for sonar dome or in-hull designs.
In certain embodiments, the echosounder may employ a command (e.g., “MEAS_TEMP”) to instruct the transducer 120 to obtain temperature readings. In some embodiments, the temperature readings are taken on power-up by default and at 1 second intervals while remaining powered-up. In response, the transducer 120 measures the temperature on the thermistors and stores these values in the memory buffer for corresponding temperature fields. In certain embodiments, temperature may be monitored by periodically sending a “READ_TEMP” command to the transducer.
Sonar transducers, especially broadband, communication, and weapons system transducers are prone to self-heating due to the high power and long duty cycles. Certain embodiments of the present invention relate to transducer thermal management. Specifically, some embodiments may use a three-pronged systems approach to control heating within acoustic transducers when they are being driven at high power levels, at large duty cycles, or both. The transmit waveform may be a pure tone, or a swept frequency, or any other broadband waveform useful for sonar or communications purposes. Duty cycle may be the ratio of pulse (or burst) duration divided by the time interval between pulses.
Certain embodiments may use passive thermal mitigation, information received from the internal microprocessor embedded in the transducer (hereinafter referenced as “eXID”), and active measurement of impedance, voltage, current, phase, and temperature to adjust power and/or duty cycle applied to a transducer to control transducer self-heating and to optimize system performance.
Some embodiments may provide redundancy in the monitoring of important characteristics within the transducer (e.g., temperature and impedance) to protect against thermal runaway and transducer failure, while optimizing the performance of the transducer-echosounder system. This redundancy allows for the system to be configured and utilized achieving the same goal in one or more of three different ways.
In certain embodiments, the echosounder 110 may include an amplifier 205 capable of providing the proper waveform 208, using the appropriate frequencies, at a suitable voltage level, and for an appropriate pulse duration and pulse repetition rate. The echosounder queries transducer 120 for internal temperatures of the transducer 120. Upon receiving the internal temperature data 222 of the transducer 120, the echosounder 110 cross-references (optionally using a logic 270) this received temperature data against stored temperature vs. impedance data of the transducer 120 (the impedance data of the transducer 120 may be stored on the transducer 120), and adjusts its power 260 and/or duty cycle 250 to optimize system performance, reduce thermal runaway and damage to the transducer 120.
In certain embodiments, the echosounder 110 may also use its ability to measure these parameters to compare the measurements with the temperature vs. impedance data provided by transducer assembly 120 (if available in the transducer) and to verify the results.
Passive thermal mitigation strategies control the heating of transducer assembly 120 components. These include the use of common medium and high thermal conductivity materials (e.g., aluminum, copper, steel, as well as composite filler-loaded plastics and tapes) to provide as much passive cooling to the transducer as possible. Active measurements, and the transducer 120 itself, provide additional thermal control if the passive measures are insufficient, thus reducing damage to the transducer and allowing for increased (higher) drive levels when the transducer is being cooled by forced convection or operating in colder environments.
The echosounder 110 may be configured to have certain capabilities in order to thermally manage a transducer and add redundancy to the system. The echosounder 110 may be configured to query and read the transducer 120 for transducer element 220 and water temperatures as well as the stored data of temperature vs. impedance to assist in the control of the power and duty cycle. The echosounder 110 may also be configured to measure impedance actively by monitoring the voltage V, current I and phase angle φ of the transducer. The echosounder 110 may also be configured to monitor the internal temperatures of the transducer components if the temperature measuring capability of transducer 120 is not used. By recognizing a change in either component temperatures or impedance, or both, the echosounder 110 can control the power level, or duty cycle, or both of the transducer 120 to match the current impedance and temperature conditions to provide constant temperature operation and/or to control against thermal runaway and optimize system performance.
The ability of an echosounder 110 to read the transducer 120 and measure impedance, voltage, current, and phase may allow any transducer 120 to be attached to the echosounder 110 and driven optimally. The echosounder 110 may be able to query the transducer 120 for stored information such as power rating and nominal operating frequency, conduct measurements on the transducer 120, adjust its own output to match the characteristics of the transducer, and optimize system performance by providing the best drive level and duty cycle for the transducer 120.
a is a high-level functional diagram of an example embodiment 801 for monitoring temperature in a transducer. The example embodiment 801 includes a temperature monitoring unit 540 that monitors temperature of an acoustic transducer (not shown) and controls the temperature of the acoustic transducer by adjusting one or more characteristics of the acoustic transducer.
b is functional diagram of an example embodiment 802 for monitoring temperature in a transducer. The example embodiment 802 includes an echosounder 110 that obtains temperature data from a transducer 120. The echosounder 110 includes a comparison unit 570 that compares the obtained temperature information against a database of known temperature values associated with transducer characteristics. The echosounder 110 further includes a control unit 560 that controls the temperature of the transducer 120 by adjusting the transducer drive waveform.
a is a high-level diagram of an example embodiment 803 for monitoring temperature in a transducer. The example embodiment 803 includes an echosounder 110 in communication with an acoustic transducer 120. The echosounder 110 employs a characteristics information obtaining unit 810 to obtain characteristics information including information regarding at least one of impedance, voltage, current, phase angle, or temperature of internal transducer components from the transducer 120. The echosounder further includes a comparison unit 570 that compares the characteristics information against a database of known temperature values associated with transducer characteristics information values. An adjustment unit 560 included in the echosounder 110 adjusts the temperature by adjusting the transducer drive waveform to reduce self-heating of the transducer.
The teachings of all patents, published applications and references cited herein are incorporated by reference in their entirety.
While this invention has been particularly shown and described with references to example embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
This application claims the benefit of U.S. Provisional Application No. 61/243,895, filed on Sep. 18, 2009 and U.S. Provisional Application No. 61/303,612, filed on Feb. 11, 2010. The entire teachings of the above applications are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 61243895 | Sep 2009 | US | |
| 61303612 | Feb 2010 | US |
