What are non magnetic speakers?
Non-Magnetic speakers are a useful tool in the audio component world. Also known as Piezo loudspeakers or simply piezos, they are most commonly found soldered to circuit boards inside of a wide variety of electronic devices. However, this represents only a small fraction of the total non-magnetic speaker market.
Traditional speakers use large magnets interacting with copper voice coils, resulting in mechanical motion that in turn, creates sounds. While these designs are very powerful and efficient, their magnetic properties have certain downsides. Due to their unique characteristics, non-magnetic speakers are seeing an uptick in integration.
As applications become more elaborate and increasingly sensitive to the world around them, engineers are looking for ways to get better results over a conventional loudspeaker.
Shop Piezo Speakers at Digi-Key
How does a Piezo device work?
Piezoelectronics are a group of minerals and compounds that have their atoms arranged in a unique way. Most elements have rigid, solid, repeating atomic arrangements. Piezo’s are a unique technology, they have their atoms arranged asymmetrically. At rest the arrangements of these atoms are in a neutral balance, but when the structure is deformed by an external force the atoms move and shift creating electrical potential. If you apply voltage instead of force you can make the ceramic compound deform on command. Apply an analog electrical audio signal and the piezo will move and play that signal as an audible sound wave
The piezoelectric elements are made of non-magnetic materials, ditching the permanent magnet that powers a traditional speaker. Piezos are now capable of providing similar sound pressure level (SPL) output in the same frequency range, providing accurate sound in the upper range as well as deep bass. For a more specific resonance frequency response there are piezo tweeters and used for a higher frequency output and woofers for lower frequencies to maximize sound quality and sound pressure.
What types of industry applications utilize piezoelectric audio components?
MRI (Magnetic Resonance Imaging)
MRI’s produce large magnetic field with high electromagnetic force, which render it impossible for typical dynamic loudspeakers to work in that environment. In addition, conventional loudspeakers will interfere with MRI’s readings, ruining the image.
Despite this, it is necessary to use an intercom system to allow the doctors in the control room to communicate with the patient in the MRI. Many patients have found it beneficial to listen to music during the procedure, especially considering that some scans can take up to 90 minutes! This is a key application for the ISL Products’ PZ-94 Speaker. You can learn more about the development of our PZ-94 speaker by reading this case study.
This is where larger piezo loudspeakers shine. The piezoelectric material is able to transmit the full range of sound with strong sound intensity to the MRI suites. Piezoelectric properties make this type of speaker uniquely suited for MRI suites. Being constructed entirely of non-magnetic substances, they are unaffected by the magnetic forces in the room while also having no effect on the scans.
Piezos are implemented in a wide range of medical applications in a variety of medical equipment from blood glucose meters to defibrillators, but the ones utilized in MRI suites are some of the largest and loudest around.
Light Weight
A surprising advantage of non-magnetic speakers is their weight, or lack thereof. Most traditional magnetic loudspeakers have a metal frame, copper coil windings, and a sizable magnet to produce sound. All three of these pieces are fairly heavy and make incorporating a speaker into a lightweight application a challenge.
Piezo loudspeakers and piezo buzzers and transducers on the other hand, are incredibly light and have unique electrical properties. Typically made of a plastic housing, quartz audio film, and little to no wire, these speakers make ideal solutions for products that need to move or travel.
If a product has to be super-light, piezo transducers can be used to resonate a device, removing the size and weight needed for a speaker cone and housing.
Efficiency
Piezo electric audio components are also a great way to increase the electrical efficiency of a system. their low electric current draw makes them an ideal choice for applications that run on battery systems. Their electrical impact on a system is significantly less than that of a magnetic speaker or tweeter.
Piezo components are also the most efficient way to produce high frequency sounds. While components like a piezo horn or black piezoelectric tweeter provide a smoother sound in the higher register, Piezo components excel as sirens and alarms in the ear-piercing sections of the audio band. This makes them a top pick for the security and safety industries. From smart lock to smoke detectors, piezoelectric elements are a top pick for their small size, high frequency output, and low power draw.
Piezo components are also used in a variety of voltages and impedance values.
Harsh Environments
Piezo speakers tend to outlive similarly performing magnetic speakers for a number of reasons. The use of phenolic cones reduces the probability of a cone or diaphragm tearing or dissolving over time. The cones are also indifferent to the humidity and moisture in the surrounding environment, as are the piezoelectric ceramic disk and plastic housing. The absence of magnetic material results in a lack of corrosion.
One of first piezoelectric loudspeakers that ISL Products developed was for use inside military vehicles. An advantage that came up during testing was that when an IED or explosion erupted nearby, it didn’t rupture the speaker.
Piezo loudspeakers are also immune to being over-driven, preventing burnouts and other failure modes due to improper use.
ISL Products has been designing and manufacturing electronic components like piezo speakers and buzzers for over 45 years. Reach out to our engineers today to discover a solution for your project!
