Using a Piezo Ceramic Ring as an Actuator

Thread Starter

philvb

Joined Sep 30, 2023
11
Hello All, I wanted to use the attached Piezo ring as an actuator to beam out ultrasonic waives. I only understand the basics of Piezo Ceramics, and in my reading and questioning, I'm not finding a use case for rings as an actuator, but more so discs. Is there a difference that would cause this Piezo Ceramic ring not to work?
 

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LowQCab

Joined Nov 6, 2012
3,925
A Piezo-Electric-Ultrasonic-Transducer acts very similar to a Tweeter-Speaker,
the exact shape of which, will determine it's pattern of dispersion.

A "Ring-Shape" may have an unpredictable, and/or, undesirable, dispersion-pattern,
whereas, a solid "Disc-Shape" will normally have a very predictable dispersion-pattern.
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Thread Starter

philvb

Joined Sep 30, 2023
11
A Piezo-Electric-Ultrasonic-Transducer acts very similar to a Tweeter-Speaker,
the exact shape of which, will determine it's pattern of dispersion.

A "Ring-Shape" may have an unpredictable, and/or, undesirable, dispersion-pattern,
whereas, a solid "Disc-Shape" will normally have a very predictable dispersion-pattern.
.
.
.
Thank you! That makes a lot of sense and clears up the murkiness.
 

bordonbert

Joined Feb 21, 2012
40
I think that, while LowQCab's advice is spot on, keep in mind that every ultrasonic transducer will have an unpredictable dispersion pattern within an enclosed space. As you probably know, the basic effect is the result of signals emanating from different spots on the transducer surface being in or out of phase when they meet at any point due to their differing path lengths to that point. This is unfortunately complicated by reflections within the room which will be quite strong if the space is relatively small. They will of course also add their contribution to the signal sources with a more random effect. The room reflections make the idea of a predictable pattern within the closed space a bit of a no-no to work out with any degree of reliability.

I do a lot of work with guitar speakers, (no, my job was as a "proper" engineer too), and they are notorious for beaming due to this concept. The bigger the transducer the more marked is the effect. That is the idea behind the "Mitchell Donut", (and why "Beam Blockers" which are a commercial solution can never work to reduce beaming). If you actually need things to be a little more predictable and the room reflection is not a factor you could look into the idea of the Mitchell Donut. He posts the full theory and solution online, and maybe try setting things up as he suggests. For a general purpose security alarm type of application or for just experimentation purposes with random scattering through a fixed closed space, I would guess it should not be necessary to worry about it.

What is your application for this and how are you planning on using the ring transducer? Do you have a dog?
 

Thread Starter

philvb

Joined Sep 30, 2023
11
Thank you for the details. This is actually experimentation using khz waives at low power on my own anatomy, joints in particular. There is research suggesting that low frequency, low power ultrasonic waives can produce healing/rejuvenation. My application would be to seal the transducer in plastic, submerge it in 3-4 inches of water, and put the joint on the actuator at very low wattage, such as 2-3 watts, which is what my reading suggests could work.
 

k1ng 1337

Joined Sep 11, 2020
906
Thank you for the details. This is actually experimentation using khz waives at low power on my own anatomy, joints in particular. There is research suggesting that low frequency, low power ultrasonic waives can produce healing/rejuvenation. My application would be to seal the transducer in plastic, submerge it in 3-4 inches of water, and put the joint on the actuator at very low wattage, such as 2-3 watts, which is what my reading suggests could work.
Please post some of this research. You might want to try the healing effects of an ordinary speaker on your sore joints then report back. I don't see how a higher frequency would be much different not to mention this area of "medicine" has been historically fraudulent.
 
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