Abstract: A detection unit has a fixed magnet, which is part of a magnetic circuit unit, and also has a movable magnet and a magnetic sensor, which are disposed below a cap. A fixed magnetic field component oriented toward a vibration direction acts on the magnetic sensor due to a leakage flux from the magnetic circuit unit. A movable magnetic field component acts from the movable magnet on the magnetic sensor in a direction crossing the fixed magnetic field component. A change in the angle of a detection magnetic field component, which is a combined vector formed from the magnetic field components in two directions, is detected by the magnetic sensor. According to the output in this detection, the operational position of the movable magnet is measured.

Abstract: In a speaker distortion correction device, an input signal passes through a nonlinear-portion correction filter and is input into a linear inverse filter. An output signal from the linear inverse filter is output into a speaker through an amplifier. For the nonlinear-portion correction filter, transfer characteristics (filter coefficients) are set that eliminate distortion due to nonlinear characteristics of the speaker. With a difference, as an error, between vibration of the speaker without distortion relative to an input signal and vibration of a vibration system of the speaker measured by a vibration measurement unit, an adaptive-algorithm execution unit performs an adaptive operation that adaptively updates filter coefficients of the linear inverse filter.

Abstract: A magnetic circuit section having a main magnetic gap and sub-magnetic gaps is used. A vibrator is vibrated by an electromagnetic force generated by a voice current, which flows through a voice coil and a magnetic flux crossing the main magnetic gap. When the voice coil approaches or enters a sub-magnetic gap, the voice current which flows through the voice coil is reversed, temporarily cut-off or attenuated.

Abstract: A vibrating unit includes a diaphragm and a bobbin, and a voice coil is secured to the bobbin. A detecting unit includes a moving magnet and a magnetic sensor. The magnetic sensor is disposed in a space surrounded by the bobbin, whereas the moving magnet is secured to an outer surface of the bobbin. Therefore, even when the moving magnet and a damper member move backward significantly, the magnetic sensor is prevented from being hit by the moving magnet and the damper member.

Abstract: In implementations of an audio system, when overheating of a speaker is detected, a controller controls first and second selectors to input an audio signal output by an audio source device to a cooling processing section and cause output of the cooling processing section to be output to the speaker. In the cooling processing section, a mixer mixes an audio signal obtained by removing a low-frequency component from the input audio signal by a high-pass filter with a cooling signal at an infrasonic frequency generated by a cooling signal generator and adjusted with a gain by a gain adjuster. An audio signal obtained by mixing the audio signal with the cooling signal is output from the cooling processing section via a nonlinear inverse filter. A gain setting section sets the gain such that power of the cooling signal matches power of the low-frequency component extracted by a low-pass filter.

Abstract: A vibrating unit includes a diaphragm and a bobbin, and a voice coil is secured to the bobbin. A detecting unit includes a moving magnet and a magnetic sensor. An annular magnet support is secured to a front edge of the bobbin, and the moving magnet is positioned and secured to the magnet support. The magnetic sensor is secured to a drive supporting unit. The moving magnet is secured to the bobbin, with the magnet support therebetween. This facilitates mounting and positioning of the moving magnet.

Abstract: A speaker includes a diaphragm having a perfectly circular hole in which a bobbin is attached and an oval or elliptical outer peripheral end. The diaphragm includes a perfectly circular cross-sectional area in the range of a predetermined height above a base having the perfectly circular hole. The diaphragm further includes an intermediate area whose outer surface has a small curvature radius above the perfectly circular cross-sectional area and an expanded area that is oval in cross section above the intermediate area.

Abstract: A detection unit has a fixed magnet, which is part of a magnetic circuit unit, and also has a movable magnet and a magnetic sensor, which are disposed below a cap. A fixed magnetic field component oriented toward a vibration direction acts on the magnetic sensor due to a leakage flux from the magnetic circuit unit. A movable magnetic field component acts from the movable magnet on the magnetic sensor in a direction crossing the fixed magnetic field component. A change in the angle of a detection magnetic field component, which is a combined vector formed from the magnetic field components in two directions, is detected by the magnetic sensor. According to the output in this detection, the operational position of the movable magnet is measured.

Abstract: In a speaker distortion correction device, an input signal passes through a nonlinear-portion correction filter and is input into a linear inverse filter. An output signal from the linear inverse filter is output into a speaker through an amplifier. For the nonlinear-portion correction filter, transfer characteristics (filter coefficients) are set that eliminate distortion due to nonlinear characteristics of the speaker. With a difference, as an error, between vibration of the speaker without distortion relative to an input signal and vibration of a vibration system of the speaker measured by a vibration measurement unit, an adaptive-algorithm execution unit performs an adaptive operation that adaptively updates filter coefficients of the linear inverse filter.

Abstract: A vibrating unit includes a diaphragm and a bobbin, and a voice coil is secured to the bobbin. A detecting unit includes a moving magnet and a magnetic sensor. The magnetic sensor is disposed in a space surrounded by the bobbin, whereas the moving magnet is secured to an outer surface of the bobbin. Therefore, even when the moving magnet and a damper member move backward significantly, the magnetic sensor is prevented from being hit by the moving magnet and the damper member.