JP3227142B2 - Wireless microphone with microphone unit as antenna - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a handheld wireless microphone, and more particularly, to a handheld wireless microphone that operates stably without being affected by contact with a metal body or a human body.

[0002]

2. Description of the Related Art Conventionally, a dipole antenna is generally used as a built-in antenna of a hand-held wireless microphone. For example, a wind screen having conductivity is connected to an output side of a transmission high-frequency circuit to form a wind screen. Japanese Patent Application Laid-Open No. Heisei 3-11962, which uses a dipole antenna as a hot-side element and uses a metal housing or a metal member (for example, a substrate or a built-in element) in a resin housing as a cold-side element. And a printed circuit board on which a conductive portion which operates as an element of a dipole antenna is formed in a resin housing of a wireless microphone (see Japanese Patent Application Laid-Open No. 10-108289). I have.

FIG. 2 is a schematic view of a hand-held wireless microphone using a wind screen as an antenna element on the hot side of a built-in antenna, with a part cut away. In FIG. 1, a wireless microphone 1 includes a conductive windscreen 3 having a microphone unit 2 provided therein, and a sound input to the microphone unit 2 is formed on a printed circuit board 5 via a lead wire 4. The transmitted signal is transmitted to the input unit of the transmission circuit 6. The transmission circuit 6 amplifies the audio signal received from the microphone unit 2 and outputs the amplified signal as a high-frequency signal. The high-frequency output section is connected to the conductive wind screen 3 via a lead wire 7. On the other hand, the housing 8 of the wireless microphone 1 is made of a conductive material such as metal, and the ground pattern on the printed circuit board 5 is connected to the housing 8 through the lead wire 9. Thus, the windscreen 3 operates as a hot-side antenna element, and the housing 8 operates as a cold-side antenna element. When the housing 8 is not conductive but is made of, for example, a non-conductive resin, an arbitrary metal member provided in the housing 8 is used as the cold-side antenna element.

As described above, since the wind screen 3 is conductive, when the wind screen 3 comes into contact with a surrounding metal body or a user's body, the output load of the transmission circuit 6 fluctuates, and noise may be generated. There is a disadvantage that there is. Further, when static electricity enters the transmission circuit 6 directly from the wind screen 3, the internal circuit may be broken. Furthermore, the housing 8 of the wireless microphone 1
Is made of metal, windscreen 3
When the user and the housing 8 are simultaneously held by hand, the antenna element on the hot side and the antenna element on the cold side are short-circuited, so that there is a problem that the transmission power fluctuates or attenuates greatly.

[0005]

SUMMARY OF THE INVENTION The present invention has been proposed to solve the above-mentioned problems associated with the conventional wireless microphone, and operates stably even when it comes into contact with a human body or a surrounding metal body. It is an object to provide a wireless microphone that can be used.

[0006]

According to a first aspect of the present invention, there is provided a wireless communication system comprising a microphone unit and a transmission circuit for transmitting an audio signal output from the microphone unit. A wireless microphone, wherein the microphone unit and a member for transmitting the audio signal from the microphone unit to the transmission circuit are antenna elements.

According to a second aspect of the present invention, in the wireless microphone according to the first aspect, the antenna element is not electrically connected to a windscreen.

According to a third aspect of the present invention, a lead wire is used as the member and a high-frequency choke is further provided, one end of the lead wire is connected to the microphone unit, and the other end of the lead wire is connected via the high-frequency choke. It is characterized by being connected to an input section of the transmission circuit.

According to a fourth aspect of the present invention, there is further provided a conductor which operates as a cold-side antenna element.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a wireless microphone according to the present invention will be described below with reference to FIG. Note that among the components shown in FIG. 1, the same or equivalent components as those in FIG. 2 are denoted by the same reference numerals.

In FIG. 1, a hand-held wireless microphone 1 has a wind screen 3 in which a microphone unit 2 is provided, and a non-conductive casing 8 in which a printed circuit board 5 is built. The input of the transmitting circuit 6 is connected to one end of the high-frequency choke 10, and the other end of the high-frequency choke 10 is connected to the output of the microphone unit 2 via the lead wire 11. High frequency choke 10
May be mounted on the printed board 5 or may be formed on the printed board 5.

The hot side terminal of the high frequency output section of the transmission circuit 6 is connected via a lead wire 12 to a junction P between the lead wire 11 and the high frequency choke 10. Even with such connection, the high frequency choke 10 exists between the connection point P and the input section of the transmission circuit 6, so that the input section of the transmission circuit 6 floats at a high frequency. From flowing into the input section of the transmission circuit 6 can be prevented. On the other hand, inside the housing 8, the cold side terminal of the high-frequency output section of the transmission circuit 6 is connected to the printed circuit board 5.
Is electrically connected to the ground pattern formed at the bottom. As a result, the lead wire 11 and the microphone unit 2
Can be configured as a hot-side antenna element and a ground pattern formed on the printed circuit board 5 as a cold-side antenna element. As the cold-side antenna element, a metal conductor in the housing 8 may be used instead of the ground pattern formed on the printed circuit board 5, or the conductor 13 may be used as shown in the drawing. It may be provided along the wall surface of the housing 8.

[0013]

As described above with reference to one embodiment, according to the first and second aspects of the present invention, the microphone unit, which is an essential component of the wireless microphone, and the microphone unit are used in the transmission circuit. Since the member to be connected is an antenna element,
The following effects are obtained. (1) Even if a conductive windscreen is used, since the windscreen is not connected to the transmitting circuit, the antenna impedance is small even when the windscreen contacts a metal object or when the windscreen is grasped by hand. Fluctuates only, and the fluctuation of the radiation electric field is small. Therefore, it is possible to provide a wireless microphone that operates stably without generating noise due to frequency fluctuation of the oscillation circuit regardless of the usage state. (2) Since the windscreen and the antenna element can be set apart from each other, even if the windscreen is conductive and may pick up external static electricity, the static electricity jumps into the high-frequency circuit of the transmission circuit. Possibility is small. For this reason, the internal circuit is unlikely to be damaged by external static electricity. (3) Since the microphone unit is used as a part of the antenna element, the number of parts can be reduced.

According to the third aspect of the present invention, the high frequency choke is used to separate the input section and the output section of the transmission circuit at a high frequency, so that the high frequency signal output from the transmission circuit flows into the input side. Thus, it is possible to prevent a microphone amplifier or the like from malfunctioning.

According to the fourth aspect of the present invention, a balanced antenna such as a dipole antenna having a microphone unit and a member or a lead wire as a hot-side antenna element and a conductor as a cold-side antenna element can be formed. This has the effect.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating a configuration of a wireless microphone according to an embodiment of the present invention, with a portion cut away.

FIG. 2 is a schematic diagram illustrating a configuration of a wireless microphone that is conventionally used, with a part thereof being cut away.

[Explanation of symbols]

1: wireless microphone, 2: microphone unit, 3: wind screen, 5: printed circuit board,
6: transmission circuit, 8: housing, 10: high-frequency choke,
13: conductor,

Claims (4)

(57) [Claims] 1. A wireless microphone comprising a microphone unit and a transmission circuit for transmitting an audio signal output from the microphone unit, wherein the microphone unit and the audio signal are transmitted from the microphone unit to the transmission circuit. A wireless microphone, wherein a member for transmitting the signal to an antenna is an antenna element. 2. The wireless microphone according to claim 1, wherein a wind screen surrounding the microphone unit is not electrically connected to the antenna element. 3. The apparatus according to claim 1, wherein the member is a lead wire, further comprising a high-frequency choke, one end of the lead wire connected to the microphone unit, and the other end of the lead wire input to the transmission circuit via the high-frequency choke. The wireless microphone according to claim 1, wherein the wireless microphone is connected to a unit. 4. The wireless microphone according to claim 1, further comprising a conductor that operates as a cold-side antenna element.