JP3463764B2 - Key telephone terminal equipment - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a key telephone apparatus comprising a main apparatus and a plurality of terminals connected to the main apparatus. And a button telephone terminal device for connecting an analog communication system and a data transmission system. 2. Description of the Related Art Conventionally, as shown in FIG. 2, a pair of analog communication lines 7a and 7b for transmitting analog signals and a pair of data transmission lines 8a and When an analog signal or the like is coupled between the two signal systems, for example, when an analog signal is amplified by the power from the data transmission lines 8a and 8b, the impedance balance of each signal system is not broken. A transformer T was inserted into the circuit to keep the balance of both signal systems. In FIG. 2, reference numeral 1 denotes a microphone for converting a voice signal of a sender into an electric signal, and reference numeral 3 denotes a microphone large enough to transmit an electric signal obtained from the microphone 1 through analog communication lines 7a and 7b. An amplifier for amplifying the output signal, Z ₁ is an output impedance, 2 is a speaker for converting a transmitted electric signal into an audio signal, and 4 is a power sufficient to drive the transmitted electric signal to the speaker 2. The differential input amplifier 5 for amplifying is a power supply circuit for extracting the power carried by the data transmission lines 8a and 8b, and has an appropriate impedance when viewed from the data transmission line sides 8a and 8b. The signal is not taken in. Reference numeral 6 denotes a data transmission circuit for extracting a data signal conveyed from the data transmission line and sending the data signal to a required portion. Reference numeral T denotes a transformer for coupling an analog communication system and a data transmission system. [0004] Thus, the primary winding t ₁ of the impedance of the transformer T is designed impedance comprising analog conversation line 7a, the line impedance of 7b equilibrium, the secondary winding t ₂ of the impedance of the transformer T A bridge circuit is configured together with the first to third impedances Z ₂ , Z ₃ , and Z ₄ . [0005] However, when the transformer T is used, the loss of the analog signal due to the coupling in the transformer T must be reduced. For this purpose, the transformer T needs to be enlarged. And the price is high, which has been an obstacle to miniaturization and price reduction of the key telephone terminal device. SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to reduce the size and cost by combining an analog communication system and a data transmission system without using a transformer T. Key telephone terminal device. SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention is directed to a key telephone terminal device which forms a part of a key telephone device, and which transmits and receives signals via analog communication lines 7a and 7b. Communication system and data transmission line 8a,
8b, the line impedance Z of the analog communication lines 7a and 7b is located at a portion where the data transmission system supplied with power from the communication line 8b is present.
Second and _L and one end is connected in series between the other end and the other analog call line 7b of the balanced circuit impedance Z _B of the balanced circuit impedance Z _B Toko to be connected to one analog conversation lines 7a 2 consisting of a bridge circuit composed of 1 side protection circuit impedance Z _A2 and Z _A1
Line, four-line conversion means 10, speaker 2, and this speaker 2
, A balanced receiving means 11 connected to the bridge circuit, a microphone 1, an amplifier 3 for amplifying the output of the microphone 1, an output of the amplifier 3, and the bridge circuit. It consists first balanced output impedance Z _C1 and the second balanced output impedance Z _C2 Metropolitan connected between ground G of the microphone 1 and the key telephone terminal device and the bridge circuit connected between the The balanced output transmitting means 12 connects the analog communication system and the data transmission system without using the transformer T. Generally, in a telephone such as a key telephone terminal device, a transmission signal and a reception signal are converted into a pair of analog communication lines 7a and 7a.
In order to perform transmission and reception while sharing b, the transmission direction of the signal is determined, and in order to prevent sidetone due to mutual signal interference, 2
A circuit as shown in FIG. FIG. 3B shows this circuit as an equivalent circuit, and it can be seen that the circuit constitutes a so-called Wheatstone bridge circuit. [0009] In FIG. 3 (a), R is receiver unit, T is sending machine, Z _L is the line impedance seen from the telephone, R _1, R ₂ is Bogawa sound circuit resistance, Z _N is balanced network impedance It is. When a signal is input to the transmitter T, one of its outputs passes through R ₁ and Z _L, and the other output passes through R ₂ and Z _N. If R ₁ · Z _N = R ₂ · Z _L , the signal of this transmitter does not flow into the receiver R. Therefore, R ₁ , R ₂ , and Z _N are determined so as to satisfy this condition. When the above circuit is made to correspond to the circuit of FIG. 1, the microphone 1, the amplifier 3, the first and second balanced output impedances Z _C1 and Z _c2 correspond to the transmitter T, the differential input amplifier 4, the speaker 2 corresponds to the receiver R, and the protection sound circuit impedances Z _A1 , Z _A2 are respectively the protection sound circuit resistances R ₁ ,
R ₂ , the balanced circuit impedance Z _B corresponds to the balanced network impedance Z _N , and the analog communication line 7a,
7b The sum Z of the respective ground impedances Z _D1 and Z _D2
D1 + Z _D2 and parallel impedance of Z ₁ (Because of Z ₁ ≪Z _D1 and Z ₁ ≪Z _D2 ) is approximately equal to the line impedance Z _L seen from the telephone. Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing a circuit configuration of the present invention. In the figure, components denoted by the same reference numerals as those in FIG. 2 indicate the same components, and the description thereof will be omitted. In the figure, Z _D1 and Z _D2 are impedances of the analog communication lines 7a and 7b with respect to the ground, Z _C1 and Z _C2 are first and second balanced output impedances respectively, Z _B is a balanced circuit impedance, Z _A1 and Z A. _A2 is the first and second side protection circuit impedances. Thus, one of the analog communication lines 7a, 7b connected to the main device and transmitting analog signals is connected to one end of the first balanced output impedance Z _C1 and one end of the balanced circuit impedance Z _B , and The other end of the balanced output impedance Z _C1 is connected to the output of the amplifier 3.
Is connected to one end of the microphone 1, and the other end of the microphone 1 is connected to the ground G of the key telephone terminal device and the second balanced output impedance Z _C2 . The other end of the second balanced output impedance Z _C2 is connected to the first soundproofing circuit impedance Z _A1 and the second soundproofing circuit impedance Z _A2 , respectively. the other end of the Z _A2 is be connected to one input of the differential input amplifier 4 is connected to the other end of the balanced circuit impedance Z _B, the other end of the first explosion-side sound circuit impedance Z _A1, the difference It is connected to another input of the dynamic input amplifier 4 and to the other analog communication line 7b. The output of the differential input amplifier 4 is input to one end of the speaker 2, and the other end of the speaker 2 is connected to the ground G of the key telephone terminal device. The data transmission lines 8a and 8b are connected to a power supply circuit 5 and a data transmission circuit 6, respectively. The power supply circuit 5 extracts the power carried by the data transmission lines 8a and 8b to generate a plus power supply + D And a minus power source -D are supplied to the amplifier 3 and the differential input amplifier 4, respectively, and the ground is connected to the ground G of the key telephone terminal device.
The data transmission circuit 6 exchanges necessary data signals with a control circuit (not shown) and the like. Here, the sum Z _D1 + Z _D2 of the impedances Z _D1 and Z _D2 between the grounds of the analog communication lines 7a and 7b.
Combined resistance of the line termination resistors Z ₁ and (Because of Z ₁ ≪Z _D1 , Z ₁ ≪Z _D2 ) It is composed of a line impedance Z _L and a balanced circuit impedance Z _B , which are approximately equal to the first and second side protection sound circuit impedances Z _A1 and Z _A2 . A two-wire / four-wire conversion means 10 using a bridge circuit (Wheatstone bridge) determines the propagation direction of the transmission signal from the microphone 1 and the reception signal to the speaker 2, and prevents side sounds. In the balanced receiving means 11 composed of the differential input amplifier 4 and the speaker 2, since the input impedance of the differential input amplifier is sufficiently high, the analog communication line 7a,
7b can be received without breaking the impedance balance of the analog communication system. Further, the first balanced output impedance Z
_C1, amplifier 3, a microphone 1, a composed balanced output transmitting means 12 at a second balanced output impedance Z _C2, can be sent without disturbing the impedance balanced analog call system. That is, if the impedance between the earth G of the key telephone terminal device of the circuit of FIG. 1 and the earth to ground is Z _E , the circuit of FIG.
And the other analog communication line 7b and the ground are connected to each other with impedance as shown in FIG. The input impedance of the differential input amplifier is sufficiently large and can be ignored. Next, in FIG. 4A, Z _A <<
Assuming that Z _D and Z _A << Z _C , the diagram can be simplified and represented as shown in FIG. From this figure, it can be seen that the pair of analog communication lines 7a and 7b are symmetrical with respect to the earth ground and satisfy the equilibrium condition. In this way, the analog communication system and the data transmission system can be directly connected without breaking the impedance balance of both signal systems. As described above, according to the present invention, two lines, four
The line converting means 10, the balanced receiving means 11, and the balanced output transmitting means 12 enable transmission / reception without breaking the impedance balance of the analog communication system without using the transformer T. This has the effect that the price can be increased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a circuit configuration diagram of a key telephone terminal device according to one embodiment of the present invention. FIG. 2 is a diagram showing a circuit example of a conventional key telephone terminal device. FIG. 4A is a diagram showing an example of a soundproofing circuit using a bridge circuit, and FIG. 4B is an equivalent circuit diagram of the circuit. FIG.
Diagrams showing impedance connections between b and the earth ground [Description of symbols] 1 Microphone 2 Speaker 3 Amplifier 4 Differential input amplifier 5 Power supply circuit 6 Data transmission circuit 7a One analog communication line 7b The other analog communication line 8a One Data transmission line 8b The other data transmission line 10 2-wire, 4-wire conversion means 11 Parallel reception means 12 Parallel output transmission means Z ₂ First impedance Z ₃ Second impedance Z ₄ Third impedance Z _L line impedance Z _N balanced network impedance Z ₁ Line termination resistance Z _D1 Ground impedance Z _{D2 of} one analog communication line 7a Ground impedance Z _{A1 of} the other analog communication line 7b First side-side sound circuit impedance Z _A2 Second protection Sidetone circuit impedance Z _B Balanced circuit impedance Z _C1 First balanced output impedance Z _C2 Second Balanced output impedance D + Positive power supply D- Negative power supply G Button Grounding of telephone terminal equipment

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) H04Q 3/58 107

Claims (1)

(57) [Claims 1] In a key telephone terminal device forming a part of a key telephone device, an analog communication system for transmitting / receiving signals via analog communication lines (7a, 7b) and a data transmission line ( 8a, 8b) at the boundary with the data transmission system receiving power supply, the line impedance (Z _L ) of the analog communication line (7a, 7b) and the balanced circuit impedance connected to one of the analog communication lines (7a) (Z _B ) and the second and first side protection sound circuit impedances (Z _A2 , Z _A1 ) connected in series between the balanced circuit impedance (Z _B ) and the other analog communication line (7b). A two-wire / four-wire conversion means (10) composed of a bridge circuit configured as described above, a speaker (2) connected to the bridge circuit, and a differential input amplifier (4) driving the speaker (2). A balanced receiving means (11), a microphone (1), an amplifier (3) for amplifying the output of the microphone (1), and a second amplifier (3) connected between the output of the amplifier (3) and the bridge circuit. 1 balanced output impedance (Z
_C1 ), a microphone (1) and a second balanced output impedance (Z _C2 ) connected between the ground (G) of the key telephone terminal device and the bridge circuit (12). ), Wherein an analog communication system and a data transmission system are connected without using a transformer (T).