A transparent electrets loudspeaker for a LCD monitor

A transparent electrets loudspeaker is proposed in this study. The motivation of the current design is to make use of the largest area of a personal device, like a cell phone, to generate sound with better quality. It is well known that the cut-off frequency of a loudspeaker strongly depends on the size of it. Obviously, the screen is the best place to put a loudspeaker. However, the loudspeaker must be thin and transparent. It is composed of a pair of transparent perforated electrodes and an electrets diaphragm. Patterned spacers are placed between the electrodes and the diaphragm to prevent them from contacting each others. The diaphragm is driven by the electrodes and tiny pores are in these electrodes to allow air move in and out, so the generated sound transmit through the electrode. Several parameters are considered in a structure-fluid coupled finite element model, and the sound pressure level (SPL) is calculated to evaluate the performance of the loudspeaker. These parameters are the geometrical and material properties of the diaphragm and electrodes, the charge density of the diaphragm, pre-tension, the gap between electrodes, ratio and size of aperture, spacer pitch, and driving voltage.