JPH05136865A - Hand-free telephone system - Google Patents

Abstract

PURPOSE:To obtain an acoustically good HF characteristic whether either a built-in speaker or another external speaker is used by changing the gain of a reception circuit in an HF circuit by detecting that both the external speaker and a microphone for HF are attached. CONSTITUTION:Since the gains of a variable gain amplifier 15 and a speaker amplifier 9 are determined previously so that optimum gain distribution is obtained when the built-in speaker 10 is used, good HF telephone conversation can be attained. Next, when the external speaker 22 is connected to an external speaker connection jack 11, the output of the speaker amplifier 9 is connected to the external speaker 22 by detaching the built-in speaker 10. Then, a detection circuit 14 changes the gain of the variable gain amplifier 15 so that the optimum gain distribution is obtained when the external speaker 22 is used by detecting both 'external speaker present' and 'HF microphone present'. Thus, even if the external speaker 22 is used, the HF telephone conversation of good sound quality can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hands-free telephone device, particularly a hands-free (hereinafter referred to as HF) circuit.
Concerning the configuration of car telephone devices, etc.

[0002]

2. Description of the Related Art FIG. 2 is a block diagram in which only parts related to HF operation in a conventional car telephone system with an HF circuit are extracted.

In FIG. 2, reference numeral 2 is a switching circuit for switching a normal communication circuit as an automobile telephone and the HF circuit 1. The common ends of the switching circuit 2 are connected to the output side of the receiving circuit 3 and the input side of the transmitting circuit 4, respectively. The output of the receiving circuit 3 is
It is connected to the receiver / amplifier 5 which drives the receiver 6 via the switching circuit 2. In addition, the microphone amplifier 8
The input side is connected to the microphone 7, and the output side is connected to the input side of the transmission circuit 4 via the switching circuit 2.

The receiving input terminal 51 of the HF circuit 1 is connected to the output side of the receiving circuit 3 via the switching circuit 2. Further, the reception output end 52 is connected to the input of the speaker amplifier 9 that drives the speaker 10. The transmission output terminal 62 is connected to the input side of the transmission circuit 4 via the switching circuit 2. Further, the transmission input end 61 is connected to the HF microphone connection jack 12. Reference numeral 13 is a detection circuit with or without an HF microphone, and its output is configured to control the switching circuit 2.

Next, the operation in the normal call and HF call states will be described with reference to FIG.

First, the HF microphone connection jack 12 has an H
When the F microphone is not connected, the normal call state is established, and the switching circuit 2 is connected in the direction of the broken line in FIG. The car-only device has a built-in microphone 7.
Using the receiver and the receiver 6, a call becomes possible. The voice input from the microphone 7 is amplified by the microphone / amplifier 8 and input to the transmission circuit 4 via the switching circuit 2 and transmitted to the other party.

The received signal is sent from the receiving circuit 3 to the switching circuit 2
The signal is amplified by the receiver / amplifier 5 through the receiver and drives the receiver 6 to enable a normal call.

Next, the HF microphone connection jack 12 has an H
When the F microphone 21 is connected, the detection circuit 13 detects the presence of the HF microphone, and the switching circuit 2 is connected in the solid line direction in FIG. Then, all the transmission and reception of the car telephone device pass through the HF circuit 1, and the speaker 10 and the HF microphone 21 enter the HF communication state.

The voice input from the HF microphone 21 is
It is input to the transmission input terminal 61 of the HF circuit 1 via the HF microphone connection jack 12. The voice output from the transmission output terminal 62 through the HF circuit 1 is input to the transmission circuit 4 via the switching circuit 2 and transmitted.

The received signal is sent from the receiving circuit 3 to the switching circuit 2
Is input to the reception input terminal 51 of the HF circuit 1. Then, the voice output from the reception output end 52 after passing through the HF circuit 1 is amplified by the speaker amplifier 9 and the speaker 10 is sounded to enable the HF call.

[0011]

However, in the above-mentioned conventional configuration, due to the recent miniaturization of the device, there is a physical upper limit to the use of a speaker having a high rating and a high efficiency as the built-in speaker, and the speaker Since the amplifier gain is selected to be high and the sound pressure is to be obtained, there is a drawback that the sound is likely to be saturated and that the HF characteristics that are satisfactory in sound quality are difficult to obtain.

Therefore, even if the user desires to use another external speaker having a higher sound pressure and a higher speaker efficiency than the built-in speaker during the HF operation, it is possible to replace it with the built-in speaker and use it as a housing. Occurrence is also difficult.

Therefore, when an external speaker is inevitably used, another HF telephone device in which the reception gain is reduced so that the use during HF operation is limited to the external speaker in advance and the gain distribution is adapted to the external speaker. Had to supply. Further, the gain distribution in this case has a drawback that the sound pressure is insufficient when the built-in speaker is used.

Therefore, a technical problem of the present invention is to provide an HF telephone device which can obtain acoustically excellent HF characteristics not only with a built-in speaker but also with an external speaker in view of the above-mentioned drawbacks. ..

[0015]

According to the present invention, there is provided a hands-free telephone device for establishing a hands-free call state by using a built-in speaker for receiving a voice and a hands-free microphone for transmitting a voice. Detects the connection status of the hands-free microphone connection terminal connected to the hands-free microphone, the external speaker connection terminal connected to the external speaker for receiving, and the hands-free microphone terminal and the external speaker connection terminal. When the connection state detecting means and the connection state detecting means detect that the hands-free microphone terminal and the external speaker connection terminal are in the connected state, respectively, the gain corresponding to the external speaker is calculated. A hands-free telephone device having a gain supply means for supplying to an external speaker is obtained.

Further, according to the present invention, in the hands-free telephone device, the gain supplying means has a variable gain amplifier for supplying a gain distribution corresponding to each of the internal speaker and the external speaker. A hands-free telephone device is obtained.

That is, the present invention provides a hands-free telephone device including a radio telephone device and a hands-free circuit,
It is configured to have a means for detecting that both the handsfree microphone and the external speaker are connected and varying the gain of the reception circuit in the handsfree circuit.

[0018]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a block diagram of an HF telephone device according to an embodiment of the present invention. Portions common to or corresponding to those of the conventional example are denoted by the same reference numerals.

The receiving output end 52 of the HF circuit 1 is connected to the variable gain amplifier 15, and its output is the speaker amplifier 9.
Connected to. The output of the speaker amplifier 9 is connected to the built-in speaker 10 via the external speaker connection jack 11. Reference numeral 14 is a circuit for detecting that the external speaker 22 is connected to the external speaker connection jack 11 and the HF microphone 21 is connected to the HF microphone connection jack 12, and the output thereof is the gain of the variable gain amplifier 15. It can be changed.

Here, the operation in the normal call state is omitted because it is the same as the conventional example, and the operation in the HF call state is shown in FIG.
Will be explained.

First, in the HF microphone connection jack 12,
When the HF microphone 21 is connected, the detection circuit 13 detects the presence of the HF microphone, and the switching circuit 2 is connected in the solid line direction in FIG. Then, the transmission and the reception pass through the HF circuit 1, and the built-in speaker 10 and the HF microphone 21 enter the HF communication state.

Here, since the gains of the variable gain amplifier 15 and the speaker amplifier 9 are determined in advance so that the gain distribution is optimal when the built-in speaker 10 is used, a good HF call can be obtained.

Next, when the external speaker 22 is connected to the external speaker connection jack 11, the output of the speaker amplifier 9 disconnects the built-in speaker 10 and the external speaker 22.
Connected to. Then, the detection circuit 14 detects both the presence of the external speaker and the presence of the HF microphone,
The gain of the variable gain amplifier 15 is changed so that the gain distribution is optimal when the external speaker 22 is used. As a result, even if the external speaker 22 is used, an HF call with good sound quality is possible.

Now, a concrete implementation circuit of the detection circuit 14 and the variable gain amplifier 15 will be described with reference to FIG.

The inside of the variable gain amplifier 15 is the HF circuit 1.
The analog switch circuit 31 connected to the reception output terminal 52 of the above and the OP amplifier circuit 32 whose gain is determined by the resistors 41, 42 and 43.

The detection circuit 14 comprises a NOR circuit 33 and bias resistors 44 and 45. The external speaker connection jack 11 is a stereo jack.

Next, the operation in the HF communication state will be described with reference to FIG.

First, when the HF microphone 21 is connected to the HF connection jack 12, one input 35 of the NOR circuit 33 is disconnected from the voltage + V applied through the bias resistor 45, so that the H level is changed. Be open.

When the built-in speaker 10 is used, the input terminal 34 of the NOR circuit 33 is at the H level because the voltage + V is applied through the bias resistor 44, and the output of the NOR circuit 33 is output. It becomes the L level.

At this time, the analog switch 31 is connected in a solid line, and the gain of the variable gain amplifier 15 is determined by the resistors 41 and 43, and the gain distribution is optimally adapted to the built-in speaker 10. ..

Next, when the external speaker 22 is connected to the external speaker jack 11, the output of the speaker amplifier 9 disconnects the connection of the built-in speaker 10 and the external speaker 2
Connected to 2. Then, the input end 34 of the NOR circuit 33
Is open, the output of the NOR circuit 33 becomes H level. At this time, the analog switch 31 is connected in a broken line, the gain of the variable gain amplifier 15 is determined by the resistors 42 and 43, and an optimum gain distribution suitable for the external speaker 22 is obtained.

[0033]

As described above, according to the present invention, by detecting that both the external speaker and the HF microphone are attached, the gain of the receiving circuit in the HF circuit can be varied, so that the built-in structure is realized. The use of either the speaker or another external speaker has the effect of obtaining acoustically good HF characteristics.

[Brief description of drawings]

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

FIG. 2 is a block diagram of a conventional example.

FIG. 3 is a specific implementation circuit in a portion of a detection circuit 14 and a variable gain amplifier 15 according to an embodiment of the present invention.

[Explanation of symbols]

1 Hands-free (HF) circuit 2 Hands-free and general call switching circuit 3 Reception circuit 4 Transmission circuit 6 Receiver (receiver) 8 Microphone amplifier 10 Built-in speaker 5 Receiver amplifier 7 Microphone 9 Speaker amplifier 11 External speaker jack 12 Hands-free microphone jack 13 Hands-free microphone detection circuit 14 Hands-free microphone and external speaker detection circuit 15 Variable gain amplifier 21 Hands-free microphone 22 External speaker 51 HF circuit reception input terminal 52 HF circuit reception output terminal 61 HF circuit transmission input terminal 62 HF circuit transmission output terminal 31 Analog switch circuit 32 OP amplifier 33 NOR circuit 34, 35 NOR circuit input terminal 41, 42, 43, 44, 45 Resistance

Claims (2)

[Claims] 1. A hands-free telephone device in which a hands-free call state is established by using a built-in speaker for receiving a voice and a hands-free microphone for transmitting a voice. A microphone connection terminal, an external speaker connection terminal for connecting to an external speaker for receiving, a connection state detection means for detecting the connection state of the handsfree microphone terminal and the external speaker connection terminal, and the connection state detection When it is detected by the means that the hands-free microphone terminal and the external speaker connection terminal are in the connected state, respectively, a gain supply means for supplying a gain corresponding to the external speaker to the external speaker. A hands-free telephone device having. 2. The hands-free telephone device according to claim 1, wherein the gain supply means has a variable gain amplifier which supplies a gain distribution corresponding to each of the internal speaker and the external speaker. Free telephone device.