JPH027753A - Hand-free telephone system - Google Patents

Abstract

PURPOSE:To avoid the wire connection between a microphone and a transmission reception/section base section by sending an output of the microphone while applying frequency modulation to the output and receiving it by a reception antenna connecting to a transmission control circuit. CONSTITUTION:An FM transmitter 90 converting a transmission signal into an FM modulation wave and a microphone 91 are provided to a sun visor 8, a solar battery 97 is used as an external power supply, the output of the FM transmitter 90 is radiated from a transmission antenna 94 utilizing an inner frame of the sun visor 8, while a reception antenna and a receiver are provided to a transmission/reception base section, the radiated transmission signal is received through them and the signal is inputted to a transmission control circuit as the sender voice signal. Thus, the need of installation of a microphone cable is eliminated, the mount of the microphone to a body is not required, external appearance is excellent and the danger of the driving due to wires at the foot of the driver is avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a hands-free telephone device mounted on a moving body such as an automobile.

(Prior Art) FIG. 6 is a configuration diagram showing a state of implementation of a conventional hands-free telephone device installed in a passenger car. In the figure, 1 is a passenger car, and a transmitting/receiving device 2 is installed in the trunk of the car. An antenna 3 is attached to the roof of a passenger car 1, and is connected to a transmitting/receiving device 2 via an antenna cable 3a. 4 is a car battery, and a power cable 4
It is connected to the transmitting/receiving device 2 by a, and supplies power to the transmitting/receiving device 2. A transmitting/receiving base portion 5 is attached near the driver's seat of the passenger car 1, and is connected to the transmitting/receiving device 2 by a control cable 5a. The upper part of the transmitting/receiving base part 5 has a mechanism as a handset holder, and a handset 6 is placed thereon. Further, the handset 6 and the transmitting/receiving head unit 5 are connected by a curl cord 6a. Furthermore, the cabin of the passenger car 1 is equipped with a small cuff for hands-free calling, and a speaker cable 7 is installed.
It is connected to the transmitting/receiving base part 5 at a, and also connected to the sun visor 8.
A microphone 9 is mounted on and connected to the transmitting/receiving base portion 5 via a microphone cable 9a. Moreover, FIG. M7 is a perspective view showing in more detail the mounting situation near the driver's seat described in FIG. 6.

FIG. 8 is a block diagram showing a conventional hands-free telephone device, in which 11 is a stabilized power supply circuit, and 12 is a handset 6.
13 is a hook switch, 14 is a key 61 in the handset 6, and an analog switch is used to switch between a handset mode for making calls and a hands-free mode for making calls using a microphone and speaker; 14 is a hook switch;
Furthermore, it is a logic circuit for instructing display contents to the display 62, exchanging and processing these contents data with the transmitting/receiving device 2, and has a function of monitoring the state of the hook switch 13, and also has a function of monitoring the state of the hook switch 13, and It also instructs switching of the switch 12. Reference numeral 15 designates a transmitting amplifier that amplifies the level from the mouthpiece 63 in the handset 6 to a predetermined level, and 16 designates an interface circuit that amplifies or attenuates the level at which the earpiece 64 in the handset 6 can operate optimally. Reference numeral 17 denotes a transmission control circuit for optimizing the hands-free telephone operation by comparing the level of the transmitting signal from the microphone 9 and the level of the receiving signal to control howling and abnormal increase/decrease in the call voice during the hands-free mode. . The operation of the transmission control circuit 17 is well known and will not be described in detail here.

Next, the operation will be explained. Car phone transmitting/receiving device 2
The basic operation of the transmitter/receiver 2 and the base unit 5 is well known, and the explanation thereof will be omitted here.
It is assumed that the receiving signal is sent from the transmitting/receiving base section 5 to the transmitting/receiving device 2, and that data is exchanged between the two.

The handset 6 is placed on the transmitting/receiving base 5, and the key 61 on the handset 6 is used to indicate that the handset 6 is placed on the transmitting/receiving base 5 when the handset mode is specified. The logic circuit 14 reads the state of the hook switch 13 and the setting of handset mode I by the key 61, and switches the analog switch 12 to the hands-free mode, that is, the transmit signal contact is set to the contact 12a side, and the receive signal contact is set to the hands-free mode. Each piece is connected to the contact 12c side.

On the other hand, the hands-free microphone 9 is supplied with power from the transmitting/receiving base 5, and is connected with a microphone cable 9a in order to send the microphone output to the transmitting/receiving base 5. In order to prevent howling, the speaker 7 is placed as far away from the microphone 9 as possible, while being placed in a position where the caller can hear the receiver sufficiently. That is, in order to prevent the sound from the speaker 7 from directly entering the microphone 9 at a high volume, the position is set so that the level is at least lower than the voice input level to the microphone 9 from the caller.

In this respect, it is desirable to place the microphone 9 near the mouth during hands-free operation. As a method of placing the microphone 9 as close to the mouth as possible, a method of attaching the microphone 9 to the sun visor 8 has already been widely practiced. In this way, microphone 9
The voice input to the device is sent to the transmission control circuit 17, where it is compared with the reception signal from the transmitting/receiving device 2, and the acoustic output of the speaker 7 on the local side is input to the micro 9, transmitted to the other side, and the audio output on the other side is is controlled so that the gain of the closed loop that becomes the acoustic input to the microphone on the other side and the output from the speaker 7 on the own side is 1 or more, that is, no howling occurs. That is, the transmission control circuit 17 controls the hands-free telephone operation to be optimal by reducing the receiving level when the transmitting level is high, and reducing the transmitting level when the receiving level is higher. ing.

In this way, in order to perform hands-free operation smoothly, it is essential to hang the hands-free microphone 9 as close to the mouth as possible. Japanese Patent Laid-Open No. 57-2033 aimed at installing a microphone as close as possible to the mouth of a person.
As described in Publication No. 59, acoustic
Some are equipped with an electrical signal converter.

(Problems to be Solved by the Invention) Since the conventional hands-free telephone device is configured as described above, the microphone 9 is not provided in the frame of glasses as described in the above-mentioned Japanese Patent Laid-Open Publication No. 57-203359, for example. In addition to being cumbersome and expensive to install and operate, in the case where the microphone 9 is mounted on the sun visor 8 as shown in FIGS. 6, 7 and 8, the microphone 9 and the transmitting/receiving base are 5, it is necessary to connect the microphone cable 9a with the wired microphone cable, which takes time and effort, and since some of the wires are also routed to the driver's feet, there is a risk of the driver's feet getting tangled. In addition to this, there were other problems, such as the wiring being exposed and making it look bad.

This invention was made to solve the above-mentioned problems, and it eliminates the need for a wired connection between the microphone and the transmitter/receiver head, and also eliminates the risk of being disturbed when worn on the body. The objective is to obtain a hands-free telephone device that can

[Means to solve the problem]

The hands-free telephone device according to the present invention uses a frequency modulation transmitter (hereinafter referred to as FM transmitter) to perform C frequency modulation (hereinafter referred to as FM modulation) and amplification of the output of a microphone that inputs voice to the transmitting/receiving device surface. is transmitted from a transmitting antenna, and the transmitted signal can be received by a receiving antenna connected to a transmission control circuit on the driver's seat side, etc., thereby eliminating the need for a microphone cable.Furthermore, the FM transmitter is equipped with a sun visor. Energy is supplied from solar cells installed on the front and windshield.

[Effect]

The microphone in this invention converts the audio signal into electrical No. 43, which is FM modulated by an oscillator. The FMI-transmitter is configured to amplify the power to a weak power level using a Ji amplifier, and the solar cell converts light energy into electrical energy and supplies it to the FM transmitter.The FM-transmitter output is also transmitted using a transmitting antenna such as the inner frame of the sun visor. radiate. On the other hand, the weak radio waves from the FMI-transmitter are received by the receiving antenna of the transmitter/receiver head, the receiver demodulates the audio output, and the demodulated output is input to the transmission control circuit as a speaker's audio signal.

[Embodiments of the invention]

An embodiment of the present invention will be described below with reference to the drawings. 1st
In the figure, 97 is a solar cell, and 94 is a transmitting antenna that also serves as the inner frame of the sun visor 8, and is made of metal with good conductivity.

Reference numeral 90 denotes an FM transmitter, which corresponds to the microphone 9 in FIG. 7 in the sense that it converts an audio signal into an electrical signal, but has the function of generating and transmitting an FM modulated wave in combination with the microphone 91. FM) Transmitter 90
A microphone 91 and an antenna 94 are housed inside the sun visor 8, and the solar cell 97 is connected to the solar cell 97 by a covered conductor 95 that passes through a hole 8a of the sun visor 8 provided in a weak electric field area near the antenna feeding point. It is connected to an FM transmitter 90. At least the front part of the sun visor 8 corresponding to the microphone 91 is made of a material with good ventilation, so as not to interfere with human voice performance. Second
The figure is a block diagram showing an FMI-transmitter 90 that sends out FM modulated waves, and 91 is an electret condenser microphone (hereinafter referred to as EC) that converts audio signals into electrical signals.
For hands-free telephone applications, highly directional EC microphones are generally used.

92 is an oscillator that generates an FM modulated wave according to the output of the microphone 91, and 93 is a buffer amplifier that removes the high frequency included in the output of the oscillator 92 and amplifies it to a required level.

Reference numeral 94 denotes a transmitting antenna that receives the output from the FM transmitter 90 and radiates radio waves, and is of a loop type here. The electromotive force of the solar cell 97 is generated by an oscillator 92. It is supplied to a buffer amplifier 93.

FIG. 3 is a block diagram of the transmitting/receiving base section 5 in this invention, in which a receiver 5 is connected to the transmitting/receiving human power side of the transmission control circuit 17.
2 is connected to the receiving antenna 5 at the input end of the receiver 52.
1 is connected. In addition, the same blocks as in the conventional example are provided except for this. The receiving antenna 51 may be mounted inside the handset head section 5 in the form of a loop antenna, but is not limited thereto.

It is desirable to place the handset head part 5 in a place with as good a line of sight as possible to the transmitting antenna 94 in the sun visor 8, but the position shown in FIG. 7 is also sufficient.

Next, the operation will be explained. First, when a caller utters a voice to make a call, the voice enters the microphone 91 and is converted into an electrical signal, and then an oscillator 92 oscillates an FM-modulated high frequency wave. This high frequency is amplified to a required level by the buffer amplifier 93, and is removed by a resonant circuit (not shown) provided on the output side thereof. The output of this FMI-transmitter 90 is guided to a transmitting antenna 94 and radiated, but its level is at a weak radio wave level (15 dBμ at a distance of 100 m).
V/m or less). Note that at this time, the solar cell 97 converts light energy into electrical energy and generates F.
MI-transmitter 90. In this case, the power consumption of the FM transmitter 90 is at most 50 mW, and in practical terms, the required area of the solar cell 97 is 5 cm x 5 cm. Since the handset base part 5 is only about 2 meters away from the FMI-transmitter 90, the output of the FMI-transmitter 90 may be very small. , this antenna 51 receives the radio waves from the FMI transmitter 90 and sends them to the receiver 52. Receiver 5
2 receives this, demodulates it, and sends it to the transmission control circuit 11 as a speaker's voice signal. Since the receiver 52 is an FM demodulator, it produces noise when there is no signal, but to prevent this, it may be equipped with a squelch. Note that the other hands-free telephone operations are the same as in the conventional example. In this case, as can be seen in FIG. 1, the microphone 91 built into the sun visor 8 is set to face the person making the call, and the solar cell 97 is placed at the front of the sun visor 8 to the extent that it does not block the driver's field of view. attached to the glass.

Furthermore, since the car body itself has a shielding effect, the radio waves emitted from the FM transmitter 90 inside the car are attenuated by about 10 dB or more to the outside of the car, and the output of the FM transmitter 90 is originally Since it is at a weak level, it will not interfere with equipment outside the vehicle.

FIG. 4 shows another embodiment of the present invention, in which the sun visor 8 is folded down to avoid sunlight by means of a power line. If the microphone 91 is unidirectional as shown in FIG.
1, and the level of the speaker's voice input to the microphone 91 decreases. As a result, problems occur in hands-free operation.

In order to solve this problem, in this embodiment, if the microphone 91 is a noise canceling type with directivity toward the front and back, its performance can be maintained even when the sun visor 8 is folded down, and ambient noise can be canceled. This makes it possible to make good calls.

FIG. 5 is a block diagram showing another embodiment of the FMI-transmitter 90. In the figure, 100 is FM) - a voice detection circuit provided in the transmitter 90 (hereinafter referred to as VOX
circuit). The voice of the speaker is converted into an electrical signal by the microphone 91, and this signal is sent to the VOX circuit 10.
By detecting 0, the buffer amplifier 93, that is, the FM transmitter 90 is controlled to operate only at this time.

A secondary battery 98 is built into the FM transmitter 90, and this secondary battery 98 is charged with power from a solar cell 97 through a diode 99, and an oscillator 92. Buffer amplifier 93. Power is supplied to the VOX circuit 100.

Therefore, according to this embodiment, it is possible to limit the current consumption from the secondary battery 98 when the hands-free telephone is not in use.

〔Effect of the invention〕

As described above, according to the present invention, an FMI-transmitter that converts a transmission signal into an FM modulated wave is provided, a solar pond is used as an external power source, and the output of the FMI-transmitter is supplied to the inner frame of a sun visor. The transmitting antenna is radiated, and the transmitting/receiving base section is provided with a receiving antenna and a receiver, through which the radiated transmitting signal is received, and this is manually transmitted to the transmission control circuit as a transmitter's voice signal. This eliminates the need to install a microphone cable, which was required in the past, and also eliminates the need to wear a microphone on the body, eliminating the hassle of operations for sending and receiving calls and the hassle of wearing it on the body. This is good, and has the effect of eliminating the danger to driving operations caused by wiring at the driver's feet.

[Brief explanation of the drawing]

FIG. 1 is an implementation diagram showing an FMI-transmitter in a hands-free telephone bag according to an embodiment of the present invention, and FIG. 2 is an FM of a hands-free telephone device according to an embodiment of the present invention.
3 is a block diagram showing a hands-free telephone device according to one embodiment of the present invention; FIG. 4 is a mounting perspective view showing another embodiment of the hands-free telephone device; FIG. 5 is an FMI - A block diagram showing another embodiment of the transmitter, FIG. 6 is a block diagram showing an example of implementation of a conventional car phone with a hands-free telephone device, and FIG. 7 is an entity showing the implementation situation of FIG. 6 in more detail. The perspective view, FIG. 8, is a block diagram showing a conventional hands-free telephone device. 2 is a transmitting/receiving device, 8 is a sun visor, 17 is a transmission control circuit, 51 is a receiving antenna, 9o is an FM transmitter, 9
1 is a microphone, 94 is a transmitting antenna, and 97 is a solar cell. In the figures, the same reference numerals refer to the same or corresponding parts. 8 Iinhebe”wa’ 91 Mike 51

Claims (1)

[Claims] A transmitting/receiving device that transmits and receives data to and from multiple lines, a transmission control circuit that controls this transmitting and receiving device so that it can optimally transmit and receive in handset mode or hands-free mode, and audio input to the transmitting and receiving device through this transmission control circuit. In order to do this, there is provided a hands-free telephone device equipped with a microphone provided on a sun visor in a mobile object, a frequency modulation transmitter that frequency modulates and amplifies the output of the microphone, and a transmitting antenna that transmits the output of the frequency modulation transmitter. A hands-free telephone device comprising: a solar cell that supplies power to the frequency modulation transmitter; and a receiving antenna that is connected to the transmission control circuit and receives a signal transmitted by the transmitting antenna.