JPS60251754A - Power supply circuit - Google Patents

Abstract

PURPOSE:To extract efficiently DC power and to eliminate signal distortion by connecting a constant voltage circuit to which capacitor is connected in parallel and an AC signal transmitting transformer in series between communication lines where an AC signal voltage and a DC voltage are superimposed. CONSTITUTION:The parallel control type constant voltage circuit 14 in which the primary winding 13 of the transformer 12 to transmit an AC signal and the capacitor 15 are connected in parallel is connected in series between two line terminals 10 and 11 through which an AC signal such as sound signal is superimposed on a DC voltage to supply DC power. The DC power is extracted from the said constant voltage circuit 14 and an AC transmission signal is extracted from the secondary winding 16 of the transformer 12. Since the DC resistance of the primary winding 13 of the transformer 12 and the AC resistance of the capacitor 15 are negligibly small, a loss in terms of DC or equivalent is hardly generated and the DC power is extracted efficiently, a loss in terms of AC or equivalent is hardly produced and the AC signal such as sound is transmitted without any distortion.

Description

[Detailed Description of the Invention] Industrial Field of Application This invention is applicable to a terminal connected to a two-wire communication line, such as a telephone line, in which the transmission and reception of alternating current signals and the supply of curved power are performed via a two-wire communication line. The present invention relates to a power supply circuit for separating and covering AC signals and DC power in communication equipment.

Conventional technology In general, when using DC power transmitted through telephone lines to operate telephone circuits, it is necessary to stably supply more DC power even if line conditions vary widely due to shortening or shortening of telephone lines. The C that can be taken out will attenuate the high T1'i signal, etc.! In order to match the impedance with the telephone line, the input impedance of the power supply circuit must be increased. In order to satisfy both of these performances at the same time, a power supply circuit is required that performs contradictory operations such as constant voltage operation for direct current and constant current operation for alternating current. Conventionally, in such a power supply circuit, as shown in Fig. 4, the connection terminals 1 and
Between 20 and 20, a three-terminal power supply circuit 3 that connects the three terminals 7, 8, and 9 to the right is connected in parallel with a telephone circuit 4 that includes a transmitting and receiving circuit, etc., and the power supply circuit 3 does not pass audio signals and is a DC component ( ]
It is constructed by connecting in series an AC/DC separation inductor 5 and a parallel control type constant voltage circuit 6, and extracts DC power from this connection point and supplies it to the telephone circuit. It is known as ψ (for example, JP-A-56
-8956 publication).

Problems to be Solved by the Invention However, when the AC/DC separation inductor 5 is
In order to have an AC impedance of Ω, an inductor of 31-1 or more is required, which not only makes the external shape bulky, but also increases the DC winding resistance, making it difficult to efficiently use DC. The drawback was that the power could not be supplied. Although not shown, a constant current circuit may be used in place of the inductor 5 in FIG. Power supply circuits are known in which elements are provided, but the former is the cut-off voltage of a constant current circuit (the minimum voltage necessary to produce constant current characteristics).
In the vicinity of the sum of the voltages of the constant voltage circuit and the voltage of the constant voltage circuit, distortion occurs in the signal transmitted on the line, and the latter generates noise due to the opening and closing of the switching element, and also This has the disadvantage that DC loss increases, efficiency deteriorates, and the number of parts increases, making the circuit configuration complex.

Embodiment This invention has been made to solve the above-mentioned drawbacks of the conventional method in which a high impedance is inserted in series with a constant voltage circuit. do. As shown in Figure 1 and Figure 2, the power supply circuit 31 consists of two lines, such as telephone lines, through which an AC signal such as a voice signal is superimposed on a DC voltage for supplying DC power and is transmitted. The first terminal 10, the primary winding 13 of the transformer 12 for AC signal transmission, and the capacitor 1 are provided.
5 are connected in parallel to the constant voltage circuit 14, and the second terminal 11 is connected in series in order to form the constant voltage circuit 1.
The transformer 12 is configured such that DC power is taken out from the secondary winding 16 of the transformer 12.
a third terminal 17 and a fourth terminal 1 for AC signal transmission;
ε3 is provided. A first circuit network 19, a transmitting (talking) amplifier 20, and a transmitting (talking) device 21 are connected between the third terminal 17 and the 71st terminal 18. Third end T-1
A second circuit network 22 connected to the terminal 7 and a third circuit network 23 connected to the first terminal 10 are connected to the mixer 24, and a receiving (talking) amplifier 25 and a receiving (talking) device 26 are connected to the mixer 24. It is connected to the fourth terminal 18 through (-).

The fourth terminal 18 is a common terminal that is normally grounded, and is connected to one end of the primary winding 13 and the secondary winding 16 of the transformer 12.
i and i are connected in the flow direction, but as shown in Fig.
0 and the second terminal 11 may be provided with a polarity matching circuit 27 for matching the polarity of the DC voltage sent from the line, and the terminals 28 and 29 may be connected to the communication line. . A capacitor 30 is inserted between the first terminal 1° and the third circuit m23 to pass an AC signal.

The mixer 24 has a second circuit network 22 and a third circuit network 23.
It is constructed by tying off the output side of. Third
As shown in the figure, the iii source circuit 31 has first to fourth terminals 10, 11, 17, '18, and is connected to the communication device (telephone) circuit 32. The human output impedance seen from the first and second terminals 10 and 11 is
For example, it is configured to have a resistance of 600Ω.

The action is thus constructed: 1 Herance 12 1
The direct current resistance of the next winding 13 and the alternating current resistance of the second winding 15 are almost ignored and are so small that most of the direct current losses are covered and the white current 1) is extracted efficiently. , almost no AC loss occurs, and AC signals such as voice are efficiently transmitted without distortion. Since the windings 13 and 1G of the AC signal transmission lances 1 to 12 are shared as part of the power supply circuit 31, the number of components is small and the circuit configuration is simple, and the power supply circuit 31 There is no need to maintain a high output impedance, and it is necessary to match it with the communication line. Rather than inserting them in series to block AC signals,
Conversely, by actively passing the AC signal through the capacitor 15, the number of parts is reduced, the circuit configuration is simplified, and efficiency is improved.

Effects of the Invention As described above, according to the present invention, it is possible to efficiently and stably extract DC mino-j from the two-wire IE line and supply it to the communication circuit, and the human power impedance of the power supply circuit can be kept high. Even if the AC signal is not in use, it is possible to transmit the AC signal without attenuation or distortion by simply matching it with the communication line.By sharing the transformer for AC signal transmission, the number of parts can be reduced. The circuit configuration can be simplified.゛

[Brief explanation of drawings]

FIG. 1 is a circuit block diagram of a communication device implementing this invention.
FIG. 2 is a diagram showing another embodiment of the J circuit 11, FIG. 3 is a dimensional block diagram showing the same basic structure, and FIG.
The figure is a circuit block diagram of a conventional telephone. 10.11... Power supply circuit terminal, 12... Transformer, 13... Primary winding, 14... Constant voltage circuit, 15...
...Capacitor, 1G...Secondary winding, 17/18...
- Secondary winding terminal, 31...power supply circuit. Utility model registration applicant Toa Tokusoku Electric Co., Ltd. Figure 3 1
1

Claims (1)

[Claims] It has a first terminal a3 and a second terminal connected to two lines through which an alternating current signal such as a famous shop signal is ψ folded and transmitted to a free current voltage for supplying direct current power, and the first terminal and the A capacitor V is connected in parallel to the primary winding of a transformer for transmitting an AC signal, and a parallel control type constant voltage circuit and a second terminal are connected in series in order, and DC power is output from this constant voltage circuit. The third and fourth terminals for transmitting the AC signal are connected to the secondary winding of the transformer.
) power supply circuit.