JPS5818359Y2 - wireless microphone - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a wireless microphone, and particularly to a wireless microphone using a lumped constant antenna such as a ferrite antenna.

Conventionally, some wireless microphones can be used either as an integrated type in which the microphone element and the transmitter body are integrated, or as a separate type in which the microphone element and the transmitter body are connected via a microphone cord.

In such wireless microphones that use lumped constant antennas such as ferrite antennas, one end of the lumped constant antenna is connected to the output side of the transmitter circuit, the other end is connected to a common line, and one end of the microphone element is connected to the output side of the transmitting circuit. was connected to the input side of the transmitting circuit, and the other end was connected to a common line.

Therefore, when this wireless microphone is used as a separate type, the high frequency current flowing through the ferrite antenna flows to the microphone cord via a common line, and the microphone cord functions as an antenna, making the transmission slower than when used as an integrated type. The radio waves were getting stronger.

Therefore, the strength of the transmitted radio waves differs between when the same wireless microphone is used as a separate type and when it is used as an integrated type.

In general, the radio wave strength that allows anyone to use a wireless microphone without a license is determined by the Radio Law, and as mentioned above, the radio wave strength differs when used as an integrated type and when used as a separate type. The following problems arise.

In other words, if an integrated type is used to meet the standards of the Radio Law, if a separate type is used, the strength of the transmitted radio waves will exceed the standards of the Radio Law, and if a separate type is used, it will be made to meet the standards of the Radio Law. However, when using an integrated type, the strength of the transmitted radio waves was weak, and satisfactory performance could not be obtained.

Therefore, it was desired to develop the Yares microphone in 2007, which could provide radio wave strength that met the standards of the Radio Law, whether it was an integrated type or a separate type.

The purpose of this invention is to provide a wireless microphone that can provide the same radio wave strength whether it is used as a separate type or as an integrated type.

This invention will be explained below based on three illustrated embodiments.

A first embodiment is shown in FIG. 2 is a transmitter main body, and a printed circuit board 4 is housed inside.

A low frequency amplification circuit 6, an oscillation modulation circuit 8, and a high frequency circuit 10 connected in series are formed on this printed circuit board 4.

Further, the printed circuit board 4 is also formed with a + side power supply common line 12 and a - side power supply common line 14 for supplying operating current to these circuits.

Each of these circuits is configured with a negative ground.

The + side power supply common line 12 is connected to the + side electrode of the battery 16,
The − side power supply common line 14 is connected to one electrode of the battery 16 .

The output side of the high frequency circuit 10 is connected to one end of the ferrite antenna 18, and the other end is connected to the + side power supply common line 12.

The input side of the low frequency amplifier circuit 6 is connected to one terminal 22 of a jack 20 provided on the transmitter body 2 via a high frequency blocking coil 18 with small inductance, and the other terminal 24 is connected to a high frequency blocking coil 26 with small inductance. It is connected to the one side power supply common line 14 via.

28 is a microphone cord, and a plug 30 is attached to one end thereof.

This plug 30 can be inserted into the jack 20.

A jack 32 is also provided at the other end of this microphone cord 28.
is installed.

This jack 32 is the same as jack 20.

Reference numeral 34 denotes a microphone element, which is configured, for example, as a dynamic type, and further includes a plug 36.

This plug 36 is the same as the plug 30, and has one terminal connected to one terminal of the microphone element 34, and the other terminal connected to an external terminal of the microphone element 34.

Therefore, by inserting the plug 36 of this microphone 34 into the jack 20, connecting the plug 36 to the jack 32 of the microphone cord 28, and connecting the plug 30 of the microphone cord 28 to the jack 20, a low frequency amplification circuit is generated. By connecting the microphone element 34 to 6, it can be used as an integrated type or a separate type.

In the wireless microphone configured in this way, the current flowing through the ferrite antenna from the high frequency circuit 10 during operation flows to the + side power supply common line 12, so the microphone cord 2
Almost no high-frequency current flows through microphone cord 28.
does not function as an antenna.

In this embodiment, a high frequency blocking coil 18.degree. 26 is provided, but these are unnecessary in theory.

However, in reality, a very small amount of the high frequency current flowing through the ferrite antenna 18 flows from the + side power supply common line 12 to the low frequency amplifier circuit 6, or flows from the + side power supply common line 12 via the battery 16 to the one side power supply. There is a possibility that it may flow to the common line 14.

As a result, a very small amount of high-frequency current flows through the microphone cord 28 in the case of the separate type, which functions as an antenna, and a very small amount of radio frequency current flows in the microphone cord 28 in the case of the integrated type and in the case of the separated type. Strength may vary.

In order to prevent this, high frequency blocking coils 18 and 26 with small inductance are provided.

However, even if these are not installed separately, by connecting the other end of the ferrite antenna 18 to the + side power supply line 12, the strength of the radio waves can be made almost the same, so these may be omitted. It is possible.

In this wireless microphone, the other end of the ferrite antenna 18 is connected to the power common line with the opposite polarity to the power common line to which the other terminal 1 of the microphone element (the terminal not connected to the input side of the low frequency amplification circuit 6) is connected. is connected, so ferrite antenna 1 is connected to microphone cord 28.
No high frequency current flows from the microphone cord 28, and the microphone cord 28 does not function as an antenna.

Therefore, in an integrated state, the best radio wave strength is the maximum radio wave strength that can be used without a license under the Radio Law)
If this wireless microphone is adjusted so that it can be used as a separate type or as an integrated type, almost the same strength of transmitted radio waves can be obtained.

In the above embodiment, each circuit is configured to have one ground, so the ferrite antenna 18 is connected to the + side power supply common line 12. However, when configured to be connected to + ground, the ferrite antenna 18
8 may be connected to the one side power supply common line 14.

Furthermore, although a dynamic type microphone element is used as the microphone element 34, an electret condenser type microphone element may also be used.

In that case, the terminal that is not connected to the input side of the low frequency amplification circuit 6 of the microphone element is connected to the one-side power supply terminal 14 if the FET, which is an impedance conversion element incorporated in the microphone element, is an N-channel. If FETfJ'=P channel, it needs to be connected to the + side power supply terminal 12.

[Brief explanation of drawings]

The figure is a schematic diagram of an embodiment of the wireless microphone according to this invention. 6...Low frequency amplifier circuit (transmission circuit), 8...
...Oscillation modulation circuit (transmission circuit), 10...High frequency circuit (transmission circuit), 12...+ side power supply line, 14... - side power supply line, 18...
Ferrite antenna (lumped constant antenna), 28...
...Microphone cord, 34...Microphone element.

Claims (1)

[Scope of utility model registration request] A transmitter circuit and + and - side power supply common lines for supplying operating current to the transmitter circuit are provided in the main body, and a microphone cord is connected between one of these power supply common lines and the input side of the transmitter circuit. A wireless microphone comprising a microphone element separate from the main body so as to be directly connectable, one end of the lumped constant transmitting antenna connected to the output side of the transmitting circuit, and the other end connected to the other end of the common power line. 0