Matsushita Electric Industrial and Matsushita Electronic Components have jointly developed a set of clear flat speakers that can be affixed to LCD monitors, without blocking their screen display, to enable sound transmission. Currently available flat speakers vibrate the flat panel from behind, using a diaphragm such as those found in conventional speakers, but cannot be mounted on the front surface of LCD monitors. Clear-panel speakers can be employed, but voice coils connected to diaphragms and magnetic circuits cannot be made transparent, and thus they block the display screen.
The Matsushita speakers have an air gap of 100 µm between their clear panel and the LCD’s glass plate. Operation relies on a conventional diaphragm, which generates variations in the surrounding air pressure when it moves. These variations are transmitted through a sound hole at the end of the display to the air gap, to indirectly vibrate the clear panel. This is what the manufacturers call “aero-drive technology.”
The speakers also support stereophonic playback. With two diaphragms, they transmit the variations in air pressure through sound holes on both sides of the display to the air gap, which requires no partition in the center of the display. So even in stereo, the screen display is free from blockage.
An added benefit is that the flat speakers consume one-twenty-fifth the power consumed by existing flat speakers. The reason, according to Sawako Usuki, senior engineer of the audio group at the Multimedia Develop-ment Center, Matsushita Electric Industrial, is that, “It requires little energy to operate a large panel like a lever as the panel is indirectly driven through the agency of air.”
No detailed information on sound quality has been disclosed, but Tadashi Abe, group manager of the audio group, explains, “These cannot provide the performance of high-end speakers that cost hundreds of thousands of yen, but they produce the same level of sound quality as speakers for similar applications, such as PDAs.”
Nonetheless, sound quality seems to be reduced somewhat at high frequencies compared to low frequencies, with the air gap set at 100 µm. With a smaller gap, high-frequency sound improves, but the volume is lower with the clear panel vibrating at a lower amplitude. The current air gap has been selected as optimal given its immediately envisioned applications. The manufacturers plan to launch touch panels with speaker functions for PDAs and car navigation equipment within this year. Prices will be higher than those of conventional touch panels and speakers, due not to material costs but to the process of attaching the clear panel with a gap of 100 µm.
Matsushita Electric Industrial hopes not only to sell the new speakers as electronic components for touch panels, but also to collaborate with the audiovisual section to develop LCD television sets with speaker functions on the display screen.
Matsushita Electric IndustrialFax (81) 6-6900-9677
www.matsushita.co.jp
