JP2990669B2 - Wireless microphone - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wireless microphone, and more particularly, to a frequency output from a control circuit in a wireless microphone by a noise signal outside a voice band received by a dynamic microphone head. The present invention relates to a wireless microphone configured to remove a signal or a signal component corresponding to an operating frequency signal of a control circuit itself (hereinafter, referred to as a frequency signal related to the operation of the control circuit) in the wireless microphone.

[Conventional technology]

Wireless microphones are used in various fields, for example,
It is used as a wireless microphone for karaoke.

For example, in laser karaoke, a wireless microphone is installed at or near a TV monitor. In this case, a frequency signal outside the audio band, for example, twice the frequency of the horizontal synchronization signal leaks from the TV monitor, and the dynamic microphone head in the wireless microphone may catch the leak signal.

[Problems to be solved by the invention]

The frequency signal twice the frequency of the horizontal synchronizing signal is out of the audio band, but the wireless microphone is provided with a key switch that raises and lowers the pitch, and the key switch control circuit detects the operation state of the key switch. A control signal indicating the pitch is sent to the receiver.

In some cases, the frequency band of the control signal substantially matches the leak frequency signal from the TV monitor. As a result, when the wireless microphone captures the leak frequency signal from the TV monitor, an erroneous control signal is sent from the wireless microphone to the receiver, and the receiver encounters the problem of erroneously raising or lowering the pitch. I have.

Such a problem may occur not only in the malfunction of pitch, but also in other control circuits in the relationship between the frequency of the noise signal and the output frequency from the control circuit. Also,
The same is true not only when a wireless microphone is used near a laser karaoke but also when it comes from other noise sources. Furthermore, not only the receiver indirectly malfunctions due to an erroneous signal from the wireless microphone, but also a control circuit in the wireless microphone may directly malfunction due to some noise signal.

The present invention removes external noise in a wireless microphone, which is related to the operation of a control circuit in the wireless microphone, with a simple configuration and at a low cost under the space- and price-restricted conditions of a wireless microphone. The purpose is to:

[Means for solving the problem]

In order to solve the above problem, the present invention provides a wireless microphone in which a noise signal affects itself or a signal output therefrom near a frequency signal related to the operation of the control circuit before the control circuit. A filter for removing a frequency signal component of the noise signal component is provided.

That is, in the present invention, a microphone head, a modulation circuit, a high-frequency amplifier circuit, and an antenna are connected in series, and a pilot tone oscillation circuit and a pitch raising / lowering circuit are connected between the microphone head and the modulation circuit. In the wireless microphone, the notch filter having a center frequency at twice the frequency of the horizontal synchronization signal of the receiver and having a signal attenuation characteristic in a band of 1 to 2 KHz is provided near the microphone head and the modulation device. A circuit, the pilot tone oscillation circuit described above,
Provided between any of the above pitch raising and lowering circuits.

[Action]

Of the noise signal components detected by the dynamic coil head of the wireless microphone, the frequency signal component related to the operation of the control circuit in the wireless microphone is removed by a filter provided before the control circuit, and direct malfunction to the control circuit is prevented. Can be prevented or no false signal is emitted from the wireless microphone. Therefore, malfunction in the receiver can be prevented.

〔Example〕

As an embodiment of the wireless microphone of the present invention, a wireless microphone used for laser karaoke will be described with reference to the drawings.

In the drawing, the wireless microphone comprises a dynamic microphone head 1, a low frequency amplifier circuit 2, a notch filter 3, a modulation circuit 4, a high frequency amplifier circuit 5, an antenna 6, a pilot tone oscillation circuit 7, a pitch raising key control circuit 8,
Pitch down key control circuit 9, pitch up key switch
10, a pitch lowering key switch 11 is connected as shown.

The dynamic microphone head 1 detects a singer's voice signal, for example, a signal in a frequency band of 20 KHz. The signal detected by the dynamic microphone head 1 is amplified by the low frequency amplifier 2. The pilot tone oscillating circuit 7 outputs a pilot tone of a voice signal,
The frequency signal of is transmitted. The voice signal and the pilot tone are modulated by the modulation circuit 4, amplified by the high frequency amplification circuit 5 into a signal having an amplitude sufficient to be transmitted from the antenna 6, and transmitted from the antenna 6 to a receiver (not shown). The receiver receives a signal from the antenna 6 and outputs a reproduced voice signal of the singer from a speaker (not shown).

On the other hand, when the singer operates the pitch-up key switch 10, during the operation, a frequency signal of, for example, 32.76 KHz is applied from the pitch-up key control circuit 8 to the modulation circuit 4, modulated and superimposed on the high frequency signal of the voice. , Are amplified by the high frequency amplifier circuit 5 and transmitted from the antenna 6 to the receiver.
Similarly, when the pitch-down key switch 11 is operated, a frequency signal of, for example, 38 KHz is transmitted from the pitch-down key control circuit 9 to the receiver from the antenna 6.

A pitch control encoder (not shown) of the receiver demodulates the frequency signal from the pitch-up key control circuit 8 or the pitch-down key control circuit 9 and converts the frequency control signal transmitted corresponding to the number of operations. The pitch is raised or lowered in response to the number of receptions.

The dynamic microphone head 1 is composed of a moving coil, detects a singer's voice signal, and radiates a TV radiated from a TV monitor installed in the vicinity thereof.
Twice the frequency of the horizontal sync signal of the monitor, 15.75KHz
Detects 31.5KHz noise signal. If the noise signal is output as it is from the antenna 6 when the notch filter 3 is not provided, the pitch control encoder of the receiver mistakenly recognizes the operation signal of the pitch raising key switch 10 and raises the pitch erroneously. .

However, in the embodiment of the present invention, the noise signal detected by the dynamic microphone head 1 is applied to the notch filter 3 through the low frequency amplifier circuit 2. The notch filter 3 has a center frequency of 31.5 KHz, which is twice the frequency of the horizontal synchronization signal of the TV monitor, and has a frequency of 1 to 2 KH near the center frequency.
It has filtering characteristics to attenuate signals in the frequency band of z. Therefore, when the signal amplified by the low frequency amplifier circuit 2 is applied to the notch filter 3, the band 20
The KHz audio signal passes through the notch filter 3, but 31.5KH
The noise signal from the TV monitor near z is attenuated (removed) and is not output from the notch filter 3. Therefore, dynamic microphone head 1 is 31.5KHz
Even when a nearby noise signal is captured, it does not affect a circuit subsequent to the notch filter 3, particularly an output signal from the pitch raising key control circuit 8.

The notch filter 3 may be provided before the pitch raising key control circuit 8, and may be provided before the low frequency amplifier circuit 2 as shown by the broken line in the figure.

The notch filter 3 having an attenuation characteristic in a narrow frequency band of about 1 to 2 KHz with a center frequency of 31.5 KHz has a simple circuit configuration, small dimensions, and is inexpensive. Therefore, it can be easily incorporated into a wireless microphone that is limited in space and price.

In the above embodiment, the case where the malfunction of the pitch is prevented by the frequency signal twice as high as the horizontal synchronizing signal from the TV monitor in the vicinity when the wireless microphone is used for laser karaoke has been described. The present invention is not limited to the above-described wireless microphone for laser karaoke, but can be applied to a case where a noise signal is removed from a wireless microphone used in an environment affected by various noise signals.

In the above-described embodiment, the case where the control signal from the raising key control circuit 8 is affected is illustrated. However, when the control circuit itself is affected by noise, the filter for preventing malfunction of the control circuit or the notch filter is used. In addition, a malfunction prevention filter can be provided in the wireless microphone.

〔The invention's effect〕

As described above, according to the present invention, even when the dynamic microphone head detects a noise signal out of the voice band, the operation of the control circuit in the wireless microphone or the control signal indicating the operation is substantially the same. Since the filter for removing noise signals having the same frequency is provided, no malfunction of the control circuit occurs in the wireless microphone, no wrong control signal is output, and the receiver does not malfunction.

[Brief description of the drawings]

The drawing is a circuit configuration diagram as one embodiment of the wireless microphone of the present invention. (Explanation of symbols) 1 ... Dynamic microphone head, 3 ... Notch filter, 4 ... Modulation circuit, 6 ... Antenna, 7 ... Pilot tone oscillation circuit, 8,9 ... Pitch up / down key control circuit, 10,11 ... Pitch up / down key switch.

Continuation of front page (58) Field surveyed (Int.Cl. ⁶ , DB name) H04R 3/00 H04B 1/04

Claims (1)

(57) [Claims] 1. A microphone head, a modulation circuit, a high-frequency amplifier circuit, and an antenna are connected in series, and a pilot tone oscillation circuit and a pitch raising / lowering circuit are connected between the microphone head and the modulation circuit. In the wireless microphone, a notch filter having a center frequency at twice the frequency of the horizontal synchronization signal of the receiver and having a signal attenuation characteristic in a band of 1 to 2 KHz is provided near the microphone head, the modulation circuit, A wireless microphone provided between the pilot tone oscillation circuit and the pitch raising / lowering circuit.