The latest addition to Murata’s family of piezoelectric ceramic speakers is ultra-thin, just 1.2mm in thickness, with side ventilation in its sturdy metal housing helping to keep the thickness down. The VSLBP1913E series’ unique rectangular shape improves its frequency response and minimises ‘dead-space’ in handheld devices. The series’ flat frequency response makes it suitable for the replay of voice and music in today’s thin and stylish mobile phone handsets.
Since piezoelectric ceramic speaker actuators have no magnetic parts such as magnets or coils, they are almost entirely EMI-free. Moreover, as piezo speakers are primarily a capacitive load, they can dramatically reduce power consumption, especially in the voice band.
Frequency response of the new rectangular speakers is much improved over circular diaphragms as the rectangular ones are multi-modal – multiple oscillation modes can be generated along the long and short sides of the diaphragm, to create as many ‘peaks’ on the frequency axis as possible. Another improved feature of the VSLBP1913E series is the soft and flexible resin film the diaphragm is mounted on. This film reduces the primary resonant frequency and damps resonant characteristics of the piezo ceramic, contributing to flattening the frequency characteristic. The diaphragm’s multi-layered piezo ceramic construction creates powerful sound, up to a sound pressure level (SPL) of 90 dB maximum (measured at 1 kHz, 5.0 Vrms, sine wave, at 0.1 m, 0 dB:20 µPa).