This section presents the 3D design printed free-form speaker based on the principles of sound reproduction electrostatic (ESR). It discusses the principles of operation and design them and then outlines the basic categories of 3D printed speakers investigated in this paper. We discuss the details of the fabrication technique of the speakers, their properties, and report their experimental evaluation. Electrostatic Sound Reproduction basic principle of electrostatic sound reproduction aresimple and explored in depth in the 1930s. 

Conductive thin diaphragm and plate electrodes are separated by material, for example, the air insulation, the dielectric permittivity ε (Figure 2a). The audio signal is amplified to ~ 1000 V and is applied to the electrodes, charging relative to the ground is connected to the diaphragm. As the charging electrode, an electrostatic attraction force is developed between the electrodes and the diaphragm

3D Printed Speaker Design Space
3D printed speaker can take many shapes and forms which leads to many unique applications. Figure 4 explores some forms that become possible with the technology of printed speakers. It is clear that we can make the traditional flat planer speaker (Figure 4, above) are common these days and that has been explored before. Therefore, we did not explore these categories speaker in this paper. At the next level of complexity speaker can take a variety of basic 3D geometric shapes including traditional speaker coneshaped, cylindrical, spherical and others (Figure 4, middle). 

All these forms produce sound in all directions around the speaker, ie, omnidirectional sound production. Note that the speaker geometric design a 3D using traditional speaker technology challenge. By using our 3D printed speaker approach, however, designing various geometric speaker is relatively trivial problem. We'll talk about it in the newspaper. Aspects of the most challenging and important than 3D printed speakers is that hey are integrated into objects of arbitrary shape, being part unobtrusive and invisible from their design (Figure 4, below). 3D printed speaker technology provides an alternative to traditional techniques integrate loudspeaker functions into objects and said.

Diaphragm Design for 3D Printed Speakers

The main factors affecting the quality of printed speakers is the design of the diaphragm. Figure 5 presents the measurement results for two diaphragm displacement 3D printed with a thickness of 1.0 mm and 0.5 mm and a weight of 5.94 g and 3.65 g, respectively, driven by a sinusoidal signal of 100 Hz. The LK-H057 Keyence® laser displacement sensor is used to measure the movement of the diaphragm at a sampling rate of 20 kHz with an accuracy 0.025 m. In addition to displacement, a Extech® 407 730 Sound Level Meter (SLM) is used to measure the sound pressure level (SPL) 30 cm from the speaker. 

Experiments show that the speaker a) printed work as designed, and b) lighter and thinner diaphragm produces significantly greater displacement and sound for louder. In fact, the movement almost doubled when we reduce the thickness of the diaphragm half. speaker emitted energy increases with increasing displacement, which is supported by measurements resulted in 54.8 and 53.2 dBSPL dBSPL for 0.5 mm and 1.0 mm diaphragm using 2 kHz input signal. The last observation, while seeming simple, are not clear. As the diaphragm becomes thinner, they have also become much more flexible. Initially it was not clear to us that the thinner, but more flexible, diaphragm will outperform a slightly thicker and stiffer. Experiments show that the stiffness of the diaphragm is not as important as the thickness and weight. This discovery allows us to significantly expand the range of materials and processes that can be used to create 3D printed diaphragm effective for speaker