Mitsubishi Denki Kabushiki Kaisha

Mitsubishi Electric Engineering Company, Limited

Noboru Kyouno

Makoto Koura

Toshimitsu Seri

Noboru Yashima

Seiki Suzuki

Masayuki Ishida

Shinji Takeuchi

Susumu Fujiwara

Isao Otsuka

Tsuyoshi Nakada

Fumio Suzuki

Teruho Yamada

Ko Nishino

Yoshiharu Osuga

Syoji Kasajima

Kazumi Honma

A motional feedback (MFB) signal control unit includes a vibration displacement calculating part which generates a vibration displacement detecting signal in response to the input of a vibration detecting signal from a vibration detecting coil of a speaker unit, a vibration speed calculating part which generates a vibration speed detecting signal in response to the input of the vibration detecting signal, a processed signal generating part which generates a feedback signal in response to the input of the vibration displacement signal and the vibration speed detecting signal, and an adder which adds the feedback signal to a sound signal outputted from a sound reproducing unit so as to input the sound signal to a driving voice coil of the speaker unit.

Sound control unit and sound system

A speaker system includes a plurality of double-voice-coil speaker units fitted to a closed type cabinet and connected in parallel with each other so that first voice coils are connected to each other at the same polarities, and second voice coils are connected to each other at the same polarities, and a single impedance compensating circuit is connected in series to the second voice coils for making the input impedance as the speaker system constant.

Speaker system

In a speaker system employing a bass reflex or Kelton type cabinet intends to solve deterioration in efficiency of a speaker caused by an increase in impedance otherwise occurring on both sides of the antiresonance frequency, and to improve the sound radiating efficiency. The speaker system comprises a plurality of dual-voice-coil speaker units (20) which are attached to a bass reflex or Kelton type cabinet (50) and made up of first voice coils (21) connected in parallel to each other with the same polarities joined into one terminal and second voice coils (22) connected in parallel to each other with their same polarities joined into one terminal, and one impedance compensation circuit (10) connected in series to the plurality of second voice coils, which are connected in parallel to each other, for thereby keeping constant the input impedance as a parameter of the speaker system.

An accident sound detection circuit includes an accident sound detection block that detects an accident sound from a sound signal inputted from an environmental sound detection unit and outputs an accident sound detection signal a power spectrum calculator for obtaining a power spectrum in regard to a sound signal when acquiring the accident sound detection signal outputted from the accident sound detection block as a trigger signal, a spectrum pattern calculator for forming a pattern of the power spectrum, and a pattern comparator circuit for comparing the formed spectrum pattern and a set pattern set in a pattern generating circuit beforehand and generating a final accident sound detection signal if the patterns coincide with each other.

Accident sound detection circuit

An accident sound detection circuit includes an accident sound detection block that detects an accident sound from a sound signal inputted from an environmental sound detection unit and outputs an accident sound detection signal, a power spectrum calculator for obtaining a power spectrum in regard to a sound signal when acquiring the accident sound detection signal, outputted from the accident sound detection block, as a trigger signal, a spectrum pattern calculator for forming a pattern of the power spectrum, and a pattern comparator circuit for comparing the formed spectrum pattern and a set pattern set in a pattern generating circuit beforehand and generating a final accident sound detection signal if the patterns coincide with each other.

To avoid degradation of the acoustic signal radiated from the opening of the ducted horn of a ducted horn type speaker, under influence of the ducted horn, below the characteristic of the speaker itself, and input terminal for receiving an audio signal, a non-recursive digital filter for varying the input audio signal, a power amplifier for amplifying the varied signal, and speaker for replaying the amplified signal are provided. The non-recursive digital filter realizes the inverse characteristic of the transfer characteristic of the ducted horn.

Acoustic replay device

An accident sound detector counts the number of records of detected accident sounds in a predetermined period of time. The accident sound detector varies the amplification of input sound signals according to the number of records or their variation to limit the number of records, thereby making it possible to increase the recording time of a recording medium without overwriting the records. The detector includes an amplifier for amplifying a sound signal from an ambient sound detector. An accident sound detector circuit and a record controller detect and record an accident sound by comparing an output value from the amplifier to a threshold. A counter circuit counts the number of detected signals of the accident sound detector circuit. A comparator compares the count value of the counter circuit with a reference count value. An amplification controller circuit controls the amplification of the amplifier based on output of the comparator.

Accident sound detector

A speaker system includes an acoustic horn disposed in a cabinet. The acoustic horn is cone-shaped, is composed of a porous sound absorbing material, and has an aperture for interconnecting a space at the rear of a speaker unit and a space in the acoustic horn. A sound absorbing member or a passive radiator is disposed at the aperture.

In a digital channel divider of the present invention, a plurality of filters are connected in parallel, which can set a desired transmission frequency response optionally for a digital input signal, so that signals outputted from each filter are outputted independently. In order to flatten the amplitude characteristic of an overall transmission frequency response of each channel and to obtain a linear phase frequency response, a time series impulse response is calculated based on an inverse characteristic and this time series impulse response is made to be a filter factor, and this filter factor and and the digital input signal are calculated by convolution operations.

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Tokyo, Japan

Noboru Kyouno