Abstract: An electroacoustic transducer includes a driver, a diaphragm 13 driven to vibrate by the driver and emitting sound, a baffle 22 holding the driver and the diaphragm 13, first openings 25 extending through the baffle 22, an acoustic resistor 23 disposed on the back side of the baffle 22, and second openings 26 extending from the front side to the back side of the acoustic resistor 23. The baffle 22 is provided on the back side of the diaphragm 13. The first openings 25 are provided in the baffle 22. The second openings 26 are each disposed above one of the first openings 25 in the acoustic resistor 23. The electroacoustic transducer exhibits an excellent frequency response even if a sufficient volume of a space is not provided on the back side of the diaphragm 13.

Abstract: A wireless receiver includes an RF muting circuit that opens and closes a signal line of a demodulated signal according to a received carrier strength level, a noise muting circuit that opens and closes the signal line according to a noise level in the modulated signal, and an RF attenuation circuit that attenuates a RF signal handled in a RF amplifier circuit, and additionally includes a reception mode switching circuit which can simultaneously select at least any two values from those comprising one of a plurality of predetermined threshold values of the RF muting circuit, one of a plurality of predetermined threshold values of the noise muting circuit and one of a plurality of predetermined amount of attenuation of the RF attenuation circuits. This configuration allows to provide a wireless receiver having a stable reception characteristics without sound interruption or interferences in a multi-wave operation of wireless microphones.

Abstract: A narrow directional microphone includes a unit case having a front end portion to which a microphone unit is mounted, and a side surface functioning as a grip, an acoustic tube formed of resin material in a tubular shape, covering the microphone unit, and attached to the front end portion of the unit case such that the microphone unit is positioned to an inner bottom portion of the acoustic tube, a piezoelectric film that is arranged in at least one part of the acoustic tube, and that generates a detection output based on a mechanical deformation of the acoustic tube, and an output signal processing unit including an attenuation circuit that attenuates an audio signal from the microphone unit with the detection output from the piezoelectric film and sends the attenuated audio signal to a signal output unit.

Abstract: In a unidirectional microphone unit, stable frequency characteristics can be obtained, and manufacturing cost is reduced while preventing increasing of an external size. A microphone cap that covers a microphone element is included, and the microphone cap includes a porous ring member arranged in the front of the microphone element to form a first communication space communicating with a front acoustic hole in a center side, and a cylindrical member supporting a peripheral edge portion of the ring member and surrounding a periphery side of the microphone element, and forming a second communication space communicating with a rear acoustic hole in the periphery side of the microphone element, and the first communication space and the second communication space are communicated through the ring member.

Abstract: There is provided a boundary microphone inside which a unidirectional microphone unit is contained, the microphone including: a base plate; and a cover plate attached onto an upper face side thereof, wherein a thin and long tubular groove acting as an acoustic tube for making unidirectivity of the microphone unit a narrow directivity is formed on the base plate side, and therein, the microphone unit is contained. In order to prevent liquid from entering the tubular groove from the outside, between a peripheral edge part of the cover plate and the upper face of the base plate, a spacer that is composed of a water repellent thin film material and allows an inside of the tubular groove and outside air to communicate via acoustic resistance with a thin air layer is disposed so as to enclose an entire periphery of the tubular groove.

Abstract: A condenser microphone unit includes a diaphragm vibrated by acoustic waves, a fixed electrode disposed to face the diaphragm, and an insulation base making contact with a rim portion of the fixed electrode to support the fixed electrode, wherein a ring-shaped protrusion is provided on a rim portion of the insulation base, the ring-shaped protrusion protruding toward the fixed electrode with a radially inward taper and having a ring-shaped distal face to oppose the rim portion of the fixed electrode, the distal face of the ring-shaped protrusion supports the rim portion of the fixed electrode, and an adhesive is provided on a tapered surface of the ring-shaped protrusion positioned between the insulation base and the fixed electrode, the adhesive having property to shrink by curing. When the adhesive is cured, contact portions of the insulation base and the fixed electrode are tightly bonded together.

Abstract: A microphone amplifier unit, to which a microphone of a first form including an LED or a microphone of a second form without including an LED is connected, includes a microphone detecting unit that detects a connection state of the microphone of the first form or the second form based on potential information supplied to a specific terminal pin of a connector. In the microphone amplifier unit, appropriate circuit setting corresponding to functions of the respective microphones is made based on information obtained by the microphone detecting unit. With the configuration, a microphone connecting device that can commonly use the microphone of the first form and the microphone of the second form with a small number of pins is provided.

Abstract: A microphone is provided that ensures the electrical connection between a unit case and an audio-signal output circuit board. The microphone includes a unit case 10 having a shape of a hollow cylinder with a closed end and accommodating an electroacoustic transducer 20, an audio-signal output circuit board 40 connected to the electroacoustic transducer, and a microphone case accommodating the unit case and the audio-signal output circuit board, wherein the audio-signal output circuit board has a receiver 41 disposed on a portion of the peripheral edge of the audio-signal output circuit board, and an open end 11 of the unit case comes into contact with the receiver and is positioned when the unit case and the audio-signal output circuit board are accommodated in the microphone case.

Abstract: A condenser microphone unit is provided that can flatten a frequency response in a high frequency band. The condenser microphone unit includes a unit case having an acoustic-wave entering hole, and a diaphragm accommodated in the unit case. The diaphragm is configured to vibrate in response to acoustic waves from the acoustic-wave entering hole. In the condenser microphone unit, an acoustic resistor is disposed between the acoustic-wave entering hole and the diaphragm. The acoustic resistor includes two elastic members in pressure contact with each other. At least one of the two elastic members is curved in a convex shape before contacting the other of the two elastic members by the pressure contact. A convex surface of one of the two elastic members is a surface that comes in pressure contact with the other elastic member.

Abstract: A connector for a microphone and a microphone are provided that can prevent loose connections to a microphone stand. The connector for the microphone is to be inserted into a connector support hole of a microphone stand. The connector includes pins to be electrically connected to the microphone stand, a connector body accommodating the pins, a sleeve disposed on the outer circumferential surface of the connector body, and an elastic member for biasing the sleeve toward the rear end of the connector body. The sleeve has an insertion portion to be inserted into a space between the connector body and the connector support hole.

Abstract: In a wireless microphone having an antenna in a lower part of a main body, a wireless microphone in which a microphone main body serves as a ground plane, which secures stable antenna ground by being gripped by a user, and which is capable of obtaining good RF performance is provided. The microphone main body includes a holder member made of metal for holding at least an antenna circuit part, a cylindrical cover member made of metal for covering a periphery of the holder member, and a cylindrical grip end member made of metal, inserted into a rear end side of the cover member, and connected with a rear part side of the holder member. The holder member has conduction with the cover member via the grip end member.

Abstract: In a wireless receiver having a plurality of antennas for wireless microphones, variation in received signal strength from the plurality of antennas is eliminated when displayed on an indicator. The receiver includes a plurality of receiving circuits respectively corresponding to the plurality of antennas outputs a received signal strength as a detection voltage received by each of the antennas, an indicator that displays the received signal strength by the number of lighting segments, a lookup table in which a correspondence relation between a value of the detection voltage and the number of lighting segments of the indicator is set for each of the receiving circuits, and a display unit that refers to the lookup table based on the value of the detection voltage output from the plurality of receiving circuits and displays a level signal based on the number of lighting segments of the indicator set in the lookup table.

Abstract: A wireless receiver includes an RSSI generation circuit that obtains RSSI output corresponding to a carrier strength level of a received RF signal; a lookup table from which a threshold value corresponding to temperature information from a temperature sensor is read based on the temperature information; a comparison circuit that generates comparison output when the RSSI output is below the threshold value read from the lookup table, in which the threshold value is one input, and the RSSI output from the RSSI generation circuit is the other input; and a muting circuit that closes a signal line of an audio signal demodulated from the RF signal, and cuts off output of the audio signal, based on the comparison output from the comparison circuit. The above configuration enables the wireless receiver to eliminate fluctuation of a reception reaching distance relative to temperature change, and ensure stable mute operation.

Abstract: A microphone includes a microphone unit that converts a sound into an electrical signal. A tubular housing houses the microphone unit and includes a rear opening portion in a side surface. A step portion surrounds the rear opening portion in an inner surface of the housing. A plate-like shielding member is attached to the step portion from an inner surface side of the housing, and a circuit board housed in the housing in contact with the shielding member includes a ground pattern its side surface and in a contact position between the circuit board and the shielding member.

Abstract: A condenser microphone includes a first grounded-plate electron tube having a plate to which a dc power is supplied, and a cathode provided with an output terminal, a self-biasing circuit that is connected to the cathode of the first electron tube and that generates a grid bias voltage of the first electron tube by voltage drop with a cathode current, and a second grounded-cathode electron tube having a plate to which a series circuit of the first electron tube and the self-biasing circuit is connected as a load circuit. A positive phase output from a first condenser microphone unit is supplied to a grid of the first electron tube, and a reverse phase output from a second condenser microphone unit is supplied to a grid of the second electron tube.

Abstract: A microphone holder holds a microphone in which an upper surface and a lower surface of a step portion are formed on an outer surface of a housing, and the microphone holder includes: a holder which is formed in a cylindrical shape having openings on upper and lower sides and in which a plurality of through passages penetrating a wall of the cylindrical shaped body is provided; a sliding portion provided movably in a circumferential direction along the openings of the holder; a lock ring configured to cover the through passage formed to the holder, from an outer side by a lock plate extending from the sliding portion; and a contact member which is movably held in the through passage and can contact on an upper surface side of the step portion of the microphone.

Abstract: An audio output circuit of a condenser microphone includes a condenser microphone unit, first and second impedance conversion circuits that receive a positive phase output signal and a reverse phase output signal from the condenser microphone unit, first and second output circuits that output an audio signal from the condenser microphone unit in a balanced line to a balanced output terminals upon receipt of outputs of the first and second impedance conversion circuits. First and second impedance conversion circuits respectively use FETs as source follower circuits and supply first and second impedance conversion outputs generated across source resistors to the first and second output circuits. A voltage regulating device that generates a constant voltage is connected in series to the source resistors. With this configuration, an audio output circuit of a condenser microphone is provided, which solves a problem of operation instability caused by variation of Idss's of the FETs.

Abstract: An ear pad to be mounted to a base body to which a speaker unit is fixed includes an elastic body in which a plurality of elastic members having different coefficients of restitution are laminated together in a sound emitting direction of the speaker unit. A skin material covers an exterior of the elastic body. The elastic body includes a first elastic member arranged at a side of the base body, and a second elastic member laminated on and fixed to the first elastic member. The first and second elastic members respectively have ring shapes having a substantially same external diameter. The second elastic member has an inner peripheral surface having a different dimension compared to an inner peripheral surface of the first elastic member, and has a portion having a larger inner diameter than an inner diameter of the first elastic member.