JPS6241488Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a dial tone sending circuit for an automatic dialing device that is not affected by voltage fluctuations in the office line and noise in the office line.

An example of a conventional auto-dial device of this type is shown in FIG. L1 and L2 are office lines, S is a switching circuit for switching the connection with the office line, T1 is a dial tone sending section, Ca is a memory that stores telephone numbers, and performs various controls for auto-dial operations. A control circuit, for example a microprocessor. L is a transformer that makes up the DC loop of the station line and picks up the audio, and A is an amplifier that connects the speaker Sp.
K1 is a numeric keypad for inputting a memorized telephone number, and K2 is a call key for reading out the memorized telephone number.

To call the other party, press the call key K2, and under the control of the control unit Ca, the switching circuit S switches the connection of the office line from the communication circuit N side to the dial tone sending unit T1 side, and connects the station line through the primary side of the transformer L. At the same time as closing the line loop, the dial tone transmitting section T1 is controlled by the control section Ca and transmits a dial tone (MF signal) corresponding to the read out telephone number of the other party to the central office line. At the same time, the dial tone generated on the secondary side of transformer L is amplified by amplifier A, and the speaker
It is now possible to monitor by emitting sounds from the SP.

Here, the dial tone sending unit T1 is directly inserted between the office lines and receives current from the office power supply, so
The dial tone transmission level tends to fluctuate due to the influence of voltage fluctuations on the central office line. In addition, it is susceptible to the effects of various noises that appear between the station lines, and in particular, noise that uses ground air as a return line passes through the route of station lines L1, L2 - dial tone sending unit T1 - control unit Ca - ground air, and its magnitude This may lead to malfunction of the control unit Ca.

In order to eliminate these drawbacks, the present invention attempts to stabilize the dial tone transmission level and block the path of harmful noise by connecting the dial tone transmission section T1 to the secondary side of the transformer L. be. The drawings will be explained in detail below.

FIG. 2 is a block diagram showing an embodiment of the present invention, in which T2 is a dial tone sending section, Cb is a control section, and dial tone sending section T2 is connected to the secondary side of the transformer L, unlike in FIG. 1. A separate power source is supplied to the station lines L1 and L2. The control section Cb is equipped with a memory for storing telephone numbers, and performs operations such as reading out the telephone numbers stored in the memory, controlling the switching circuit S, and controlling the dial tone sending section T2, and is similar to the conventional one. To call the other party, press the call key K2. Under the control of the control unit Cb, the switching circuit S switches the connection from the office lines L1 and L2 from the communication circuit N to the primary side of the transformer L.
Cb reads the telephone number of the other party stored in the memory, controls the dial tone transmitter T2, and transmits the dial tone corresponding to the telephone number to the transformer L.
is sent to the central office lines L1 and L2 through the amplifier A.
The sound is amplified and emitted from the speaker SP.

Here, the dial tone sending section T2 is inserted into the secondary side of the transformer L, so it does not receive direct current from the office lines L1 and L2 and is connected to the local battery power supply (V+).
The dial tone transmission level is stable because the current is supplied from the dial tone. In addition, the ground air return noise that enters from the office lines L1 and L2 is blocked by the transformer L and does not enter the dial tone sending circuit T2, and therefore does not pass through the part of the control unit Cb that controls dial tone sending. Therefore, the control section Cb will not malfunction due to noise when transmitting the dial tone.

As explained above, according to the present invention, the dial tone transmission level is stable, and the control unit Cb does not malfunction due to the influence of station line noise.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing a conventional example of an auto-dial device, and FIG. 2 is a block diagram showing an embodiment of the present invention. L1, L2...Station line, S...Switching circuit, T1,
T2...Dial tone sending unit, Ca, Cb...Control unit, N...Telephone circuit, L...Transformer, A...Amplifier, K1...Numeric keypad, K2...Call key.

Claims (1)

[Scope of utility model registration request] It is equipped with a switching circuit for switching the connection to the central office line, a dial tone transmitter, a transformer for configuring the central office line loop and for picking up audio, a monitor circuit, and a memory for storing telephone numbers, which are stored in the memory. In the automatic dialing apparatus, the dial tone transmitting section is configured to read out a telephone number that has been received, and a control section that drives the dial tone transmitting section and the switching circuit to control transmitting the telephone number to the central office line, wherein the dial tone transmitting section is modified as described above. 1. An auto-dial device, which is inserted into the secondary side of a device, and is configured to supply current from a local battery to a dial tone sending section.