Vertical drive technology is a unique speaker drive system developed by Sony as the basis for a totally new concept in listening styles: speakers as an inherent part of the interior décor. This technology has been commercialized as Sony's Sountina speaker system, which combines superb audio quality with sophisticated design. This page describes the principle behind vertical drive technology, and the audio and design benefits it provides.
What is Vertical Drive Technology? --- The Vertical Drive Principle
Vertical drive technology generates sound waves by means of vibrations created by an actuator mounted on the end surface of a diaphragm. Its key feature is the fact that sound is emitted in a vertical direction relative to the direction of vibrations produced by the actuator. Sony has used this principle in its Sountina speaker system, which works by vibrating the end surface of a cylindrical diaphragm, instantly propagating compressional waves along the length of the cylinder. These compressional waves apply force to the cylinder in a diametrical direction (vertically relative to the length of the cylinder) according to Poisson's ratio (*) of the solid. This force produces vibration in a diametrical direction, thereby emitting sound from the entire surface of the cylindrical diaphragm.
* This is the ratio between the extension or contraction that occurs along the direction of force applied to an elastic object, and contraction or extension occurring in a direction vertical to the direction of force.
The following provides an analysis of vibration modes on the diaphragm to explain vibration levels. The colors used to represent the vibration levels indicate the amplitude radially throughout the diaphragm. Figure 2 shows the result when a 5KHz sine wave (*) signal is used to vibrate the diaphragm through multiple vibrators. In this case, an analysis of vibration levels shows that amplitude is greatest in a diametrical direction, especially around vibration points, and that vibration does not spread throughout the entire diaphragm. As shown in Figure 3, however, if vibration is caused under the same conditions by actuators on just the end surface of the diaphragm, it spreads evenly throughout the entire diaphragm.
Sony wanted to use this drive technology to vibrate the diaphragm efficiently and produce high-quality sound. It achieved this by developing a new actuator with excellent responsiveness and the ability to produce large stresses. By using vibration analysis simulations and Sony's independently-developed audio materials measurement technology, Sony was able to select the optimal shape and materials for the diaphragm.
* This is the name of the waveform. Others include alternating wave form and pulsating waveform.
