Disney Research engineers Yoshio Ishiguru and Ivan Poupyrev formally presented their work on 3D interactive speakers at the recent Conference on Human Factors in Computing Systems in Toronto.
The speakers are based on electrostatic speaker technology that was first explored in the early 1930s but never widely adopted. This type of speaker is simpler than conventional electromagnetic speakers and includes no moving parts, which makes it suitable for producing with a 3D printer.
An electrostatic speaker consists of a thin, conductive diaphragm and an electrode plate, separated by a layer of air. An audio signal is amplified to high voltage and applied to the electrode; as the electrode charges, an electrostatic force develops between it and the diaphragm, causing the diaphragm to deform and produce sound as the audio signal changes.
A typical frequency response has not been made available for these types of speaker but it has been noted that there is relatively little bass response, although it does a good job of producing high frequency sounds, such as chirping birds, computer generated blips, and even the human voice. Sound reproduction of up to 60 decibels is possible.
“What’s more, it can generate sound across the entire face of the speaker,” Ishiguro noted. That makes it possible to not only produce directional, cone-shaped speakers but also omnidirectional speakers in which the entire 3D surface emits sound. Also, the speakers can be built with any number or configuration of electrodes; placing multiple electrodes in a curved speaker, for instance, makes it possible to vary the direction of the sound emitted.
Ishiguro and Poupyrev created conductive surfaces by spraying a nickel-based conductive paint and developed a method for making full-body compliant diaphragms using negative molds produced by 3D printing and spraying them with the conductive paint and with a polyethylene coating. Once multi material 3D printers are developed that can print functional electrical circuits and electrodes, these manual steps could be eliminated.
Despite the lack of bass, these look awesome and as well as having obvious commercial and industrial applications there would be a whole range of regular consumers people would be very happy with having their very own, unique, speakers in their life.