JP2002300074A - Oscillation preventing circuit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an oscillation preventing circuit that attains a stable two- way speech without causing oscillation between transmission/reception sections of both communication units where a transmission section and a reception section are installed at the same place or close to each other without the need for gain adjustment to prevent the oscillation. SOLUTION: The oscillation preventing circuit is used for communication between two points where one communication unit and other communication unit are connected via a transmission system 31 to attain 2-way communication. The oscillation preventing circuit is provided with switch circuits 38, 42 that are respectively provided to a transmission section 32 and a reception section 33 to turn on/off the flow of a signal and with a control circuit 45 that controls the switch circuits so that the switch circuit of the reception section is turned off when the switch circuit of the transmission section is turned on and the switch circuit of the reception section is turned on when the switch circuit of the transmission section is turned off in a way that both the switch circuits are not simultaneously turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention
Handsets for mobile communication such as HS, general telephones, earphone microphones in general, translators, loudspeakers for deaf and vocal cord injured persons, guides for travel agencies, announcers, trains The present invention relates to an oscillation prevention circuit which is incorporated in various communication devices such as a conductor communication device and an operator headset, and is effective in preventing oscillation of these communication devices.

[0002]

2. Description of the Related Art Conventionally, as a communication device, for example, a wired and wireless slave unit used for mobile communication such as a mobile phone or a PHS is known.
When two-way communication is performed with a communication device of the other party via a transmission system including a radio wave relay unit for telephones such as DOCOMO, electrical communication including sound waves transmitted through the space of the transmission and reception unit of both communication devices is performed. Oscillation may occur due to the formation of a loop. Since this oscillation phenomenon occurs when the loop gain of the electrical coupling becomes 1 or more, in order to guarantee the loop gain to be 1 or less, not only the transmission part and the reception part are integrated or provided, but also
It is necessary to take countermeasures such as not being able to make it very close or not being able to increase the gain of the communication equipment so much. For both wired and wireless, measures against noise of communication equipment, miniaturization, weight reduction, reduction of manufacturing cost, etc. There is a big problem in proceeding.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems and does not cause an oscillation phenomenon between the transmitting and receiving units of both communication devices. It is an object of the present invention to provide an oscillation prevention circuit which can be provided at or near the same portion, and which does not require a gain adjustment for oscillation prevention, and which enables stable two-way communication.

[0004]

In order to achieve the above object, according to the first aspect of the present invention, there is provided a microphone for transmitting a signal such as voice by one communication device, a transmitting section including an amplifier circuit,
The other communication device includes a speaker or earphone that receives a signal, a receiver including an amplifier circuit, and the other communication device includes a transmitter including a similar microphone and an amplifier circuit, and a receiver including a speaker or earphone and an amplifier circuit. These two communication devices are used for point-to-point communication in which two-way communication is possible by being connected via a transmission system, and are provided in a transmitting section and a receiving section, respectively. on·
The switch circuit to be turned off, and the switch circuit of the receiver is turned off when the switch circuit of the transmitter is turned on, and the switch circuit of the receiver is turned on when the switch circuit of the transmitter is off, And a control circuit for controlling so that they are not always turned on at the same time.

According to a second aspect of the present invention, in the first aspect, the control circuit comprises: a pair of switch driving circuits for driving a switch circuit of the transmitting section and a switch circuit of the receiving section; A flip-flop circuit that alternately switches on and off so that the circuits are not always turned on simultaneously, and an oscillation circuit that operates the flip-flop circuit.

[0006]

An embodiment of the present invention will be described with reference to the drawings. The embodiment is applied to a mobile communication handset that is a mobile phone or a PHS. The environment in which the mobile communication handset is used is as shown in FIGS. 1 and 2, and 1 is for managing a radio wave of a mobile communication such as a mobile phone or a PHS, for example, Nippon Telegraph and Telephone Company. (NTT) Indicates a telephone radio wave relay unit such as a main office. Reference numeral 2 denotes a mobile phone as mobile communication for receiving a radio wave (strong radio wave) transmitted from the radio wave relay unit 1, and has a function as a normal telephone such as a transmitter and a receiver. Reference numeral 3 denotes a slave unit for the mobile phone 2, which includes a transceiver 4 and a transceiver 5. The transceiver 4 is detachably attached to the external connection terminal 6 of the mobile phone 2, and when the mobile phone 2 receives a radio wave, transmits a radio wave (weak radio wave) weaker than the radio wave to the transceiver 5. This weak radio wave is a radio wave that does not touch the regulations of the Radio Law, for example, a radio wave that reaches only a range of approximately 5 m. The transceiver 5 receives a weak radio wave from the transceiver 4 and notifies the mobile phone 2 of an incoming call. The transceiver 5 is smaller than the mobile phone 2, in other words, ultra-small as a hearing aid, and is detachably attached to the person holding the mobile phone 2.

The transmitter / receiver 5 is integrally provided with a transmission / reception section 7 formed to have a size that fits into an ear hole, protruding from its surface. The transmission / reception unit 7 includes a telephone microphone 10, an incoming call speaker 11, and a telephone speaker 12. 15 is a rechargeable battery. SW ₁ is a switch that turns off the melody sound for notifying that the mobile phone 2 is receiving a call with one touch, and turns on / off the transceiver 5 itself with a long touch, and SW ₂ is a telephone built in the mobile phone 2. A switch for selecting an arbitrary party from a plurality of parties registered in the book memory and enabling a call, SW ₃
Is a switch for turning on / off the call state of the mobile phone 2 through the slave unit 3. The transmitter / receiver 5 of the slave unit 3 is hooked on the ear of the wearer by a hook 21 attached to the front side through an opening / closing hinge 20 as shown in FIG.
Alternatively, a hook 23 attached to the back surface is attached to a breast pocket, a neck, and a female strap for women. In the figure, W indicates the opening / closing width of the hook 21.

[0008] Figure 3 is a block diagram of an oscillation prevention circuit incorporated in the transceiver 5, in this drawing the SW ₁ to S
Normal reception circuit including the W ₃ being omitted. Reference numeral 31 denotes a transmission system including the mobile phone 2 and the radio wave relay unit 1. The transmission / reception unit 7 of the transceiver 5 whose left side of the transmission system is, for example, its own side.
The right side shows the transmission unit 35 and the reception unit 36 provided in the transmission / reception unit of the communication device of the other party on the right side. The transmitting section 32 on its own side is composed of the microphone 10, an amplifier circuit 37, a switch circuit 38 for turning on / off a signal flow, and an amplifier circuit 39. Receiver 33
Is composed of an amplifier circuit 41, a switch circuit 42 for turning on / off a signal flow, an amplifier circuit 43, and the speaker 12.

The switch circuit 38 and the switch circuit 42 are connected to a control circuit 45 for controlling the on / off of the switch circuits 38 and 42 by generating clock pulses. The control circuit 45 includes switch driving circuits 46 and 47, a flip-flop circuit 48, and an oscillation circuit 49. The switch drive circuit 46 is connected to the switch circuit 38, and the switch drive circuit 47 is connected to the switch circuit 42. A flip-flop circuit 48 is connected to both switch driving circuits 46 and 47,
When the switch circuit 38 is on, the switch circuit 42 is turned off, and when the switch circuit 42 is on, the switch circuit 38 is turned off, so that the two switch circuits 38 and 42 are not turned on at the same time. Like that.
FIG. 4 shows the switch timing of both switch circuits 38 and 42. Further, an oscillation circuit 49 is connected to the flip-flop circuit 48 to operate the flip-flop circuit 48. The transmitting unit 35 and the receiving unit 36 of the other party have only a part of the configuration shown, omitting the amplification circuit and the like. That is, the transmitting unit 35 of the other party has the microphone 52, and the receiving unit 36 has the speaker 53.

The above-mentioned switches SW _{1 to} S
When _three switches are simultaneously turned on (for example, switches SW ₁ and SW ₂ ) during a call state, the microphone 10 of the transmitting unit 32 is turned off, and W ₃ transmits its own voice to the other party. If any two switches are simultaneously turned on again (for example, switches SW ₁ and SW ₂ ), the transmitting section 32
The microphone 10 is turned on.
Therefore, when a third party interrupts a call with his / her handset 3 during a call, the other party can hear the voice of the interruption by the third party. By turning off, a non-call state can be established.

In use, the transceiver 4 is connected to the mobile phone 2
In accordance with the surrounding noise level, the transmitter / receiver 5 is inserted into the ear of the wearer via a hook 21 like a hearing aid, and the transmission / reception unit 7 is just inserted into the ear according to the degree of the surrounding noise. Hook and attach. When the switch SW1 of the transceiver 5 is turned on with a long touch, the mobile phone 2 and the handset 3 enter a standby state and wait for an incoming call and an outgoing call.

Next, when the switch SW1 of the transmitter / receiver 5 is touched one time, a call is established, and the sound collected from the microphone 10 of the transmitter 32 is amplified by the amplifier circuit 37 as shown in FIG.
To the switch circuit 38. At this time the switch circuit
38 is turned on / off by the control circuit 45 with a pulse wave having a repetition frequency of 30 to 50 KHz, for example, which cannot be recognized as a voice by a person. In other words, the timing at which the switch circuit 38 is turned on is always shifted between the switch circuit 42 and the switch circuit 42,
When the switch circuit 38 is on, the switch circuit 42 is turned off, and when the switch circuit 38 is off, the switching timing is controlled so that the switch circuit 42 is turned on. Thereafter, when the signal sent to the amplification circuit 39 is sent to the transmission system 31 including the mobile phone 2, the switching component applied in the switch circuit 38 is removed by a filter or the like added to the amplification circuit 39, and Sent to 31. The signal transmitted to the other party by the transmission system 31 is amplified as voice through the speaker 53 of the receiver 36 of the other party's mobile phone or telephone.
On the other hand, the other party that has heard this voice sends out the voice to the transmission system 31 through the microphone 52 of the transmitting unit 35.

[0013] The mobile phone 2 which is a master unit included in the transmission system 31
Is sent from the amplifier circuit 41 of the receiver 33 to the switch circuit 42, and the amplifier circuit 43
Through the speaker 12. As a result, two-way communication is performed. In such a two-way call, the microphone 10 of the transmitting section 32 and the receiving section 33 are usually used.
When the speakers 12 of the
The voice loudspeaked by 12 is captured by the microphone 10, and the voice loudspeaked by the loudspeaker 53 of the other party is received by the microphone 52 of the other party through the transmission system 31, forming a loop, and the oscillation phenomenon occurs. Switch circuits 38 and 42 by control circuit 45 as described above
Oscillation is prevented by the on / off control of. In particular, when the surrounding noise is severe such as a train passing sound or in a pachinko parlor, the conventional type (it was impossible to integrate a microphone and a speaker to collect and generate sound in the ear). Although two-way communication was difficult, smooth two-way communication was possible with the above-mentioned oscillation prevention. Also, since no gain adjustment or the like is required, volume adjustment during transmission / reception is possible.

In the above, in the case where the other party does not have the same oscillation prevention circuit function as in this embodiment, such as a normal mobile phone or telephone, there is no problem in bidirectional communication, but the same oscillation prevention circuit function is added. In such a case, if the control timing of the oscillation prevention circuits of both communication devices has the same or slightly different control timing, a communication failure occurs, and in such a case, the other party transmits a signal such as voice to the transmission system 31. Before transmission, the switching component on the other side must be removed by the filter on the other side and sent to the transmission system 31 in the same manner as described above.

In the above, in order to prevent the transmitting unit 32 and the receiving unit 33 from operating at the same time, for example, when the power is turned on,
First, the oscillation circuit 49 is operated first, and after the oscillation prevention control is enabled, all circuits of the transmission / reception circuit including the transmission unit 32 and the reception unit 33 are set to standby.
When the power is turned off, the operation is reversed.

In the embodiment, the speakers 12 and 53 are shown as communication devices of the receivers 33 and 36, but they may be earphones. Further, the control circuit 45 for controlling the on / off of the switch circuits 38 and 42 is only one preferable example, and other specific circuits may be used as long as they have the same effect.

[0017]

Since the first and second aspects of the present invention have the above-described configuration, no oscillation phenomenon occurs between the transmitting and receiving units of both communication devices, and the transmitting unit and the receiving unit are provided together. Alternatively, it can be installed in close proximity, and it is not necessary to adjust the gain for preventing oscillation, and stable two-way communication can be performed. In particular, it is an epoch-making one that allows two-way communication without being affected by external noise. In addition, since the configuration is simple, it is possible to expect an excellent effect that the manufacturing cost can be kept relatively low and the size and weight can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing an embodiment of the present invention.

FIG. 2 is a side view of the transceiver on the slave side.

FIG. 3 is a block diagram of an oscillation preventing circuit and the like incorporated in the transceiver on the slave side;

FIG. 4 is a diagram showing switch timing of a switch circuit.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 Radio wave relay unit for telephone 2 Mobile phone (mobile communication) 3 Remote unit 4, 5 Transceiver 6 External connection terminal 7 Transmitter / receiver unit 10 Microphone for call 11 Speaker for incoming call 12 Speaker for call SW ₁ , SW ₂ , SW ₃ switch 21, 23 Hook 31 Transmission system 32, 35 Transmitter 33, 36 Receiver 37, 39, 41, 43 Amplification circuit 38, 42 Switch circuit 45 Control circuit 46, 47 Switch drive circuit 48 Flip-flop circuit 49 Oscillation circuit

 ────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yasutoshi Taniguchi 3-30-1 Wakuhakuhigashi, Higashi-ku, Fukuoka City, Fukuoka Institute of Technology F term (reference) 5K011 DA05 DA17 DA21 GA04 JA01 KA06 5K023 AA08 BB10 EE04 5K027 AA12 BB03 DD10 DD11 DD14 GG08 MM04

Claims (2)

[Claims] 1. One communication device includes a microphone for transmitting a signal such as a voice, a transmitting section including an amplifier circuit, a speaker or an earphone for receiving information, and a receiving section including an amplifier circuit, and the other communication apparatus includes: The device is composed of a transmitting unit including a similar microphone and amplifier circuit, and a receiving unit including a speaker or earphone and an amplifier circuit, and these two communication devices are connected via a transmission system to enable two-way communication. A switch circuit provided in each of the transmitting and receiving sections for turning on / off a signal flow, and a switch circuit for turning on / off the switch circuit of the transmitting section. When the switch circuit of the receiver is turned off, the switch circuit of the receiver is turned on when the switch circuit of the transmitter is off, and the control circuit is controlled so that it is not always turned on at the same time. Oscillation prevention circuit, characterized in that it comprises and. 2. A control circuit comprising: a pair of switch drive circuits for driving a switch circuit of a transmission unit and a switch circuit of a reception unit; and a control circuit for turning on the switch drive circuits so that the switch circuits are not always turned on at the same time. 2. The oscillation prevention circuit according to claim 1, comprising a flip-flop circuit that alternately switches off and an oscillation circuit that operates the flip-flop circuit.