JPH0338953A - Dialer integrated circuit for telephone set - Google Patents

Abstract

PURPOSE:To attain the transmission of a data signal with a sufficient signal level at a receiver side by using a signal level switching signal from an input output control circuit to switch an output level of a signal level switching circuit. CONSTITUTION:The circuit is provided with a key interface circuit 2 for key input detection, an input output control circuit 3 controlling a signal with the said interface circuit 2, a DTMF(Dual Tone Multi Frequency) signal generating circuit 4 generating a DTMF signal equivalent to an input data from the input output control circuit 3, a DTMF signal amplifier circuit 5 amplifying the DTMF signal from the said DTMF signal generating circuit, and a signal level switching circuit 6 to vary the level of the DTMF signal according to the signal level switching signal from the input output control circuit 3. Thus, in the case of sending a dial signal and a data signal, the level of the DTMF signal is switched automatically to ensure the reception of the data signal.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a (semiconductor) integrated circuit for dialing a telephone (hereinafter referred to as dialer IC), and in particular to a dialer IC (hereinafter referred to as dialer IC).
The present invention relates to a dialer IC that sends out a Tone Multi Frequency signal (hereinafter referred to as a DTMF signal) as dial data.

[Conventional technology]

Conventionally, D is used as a telephone dial signal or data signal.
There is a method using TMF signals. This DTMF signal is
The numbers 0 to 9 and the symbols -X-, #, and AD are represented by a combination of two signals with different frequencies. This is shown in Table 1.

Table 1 This DTMF signal is generated by a dialer IC, which will be explained with reference to the drawings.

FIG. 5 shows a block diagram of an example of a conventional dialer IC. In the figure, 1a is a key input section, 2 is a key interface circuit, 3 is an input/output control circuit, 4 is a DTMF signal generation circuit, 5 is a DTMF signal amplification circuit, and 9 is a dialer IC.

Next, the operation will be explained. When input to the key input section 1a, the key interface circuit 2 detects the input, and data corresponding to the key input is sent to the input/output control circuit 3. This input/output control circuit 3 sends data to a DTMF signal generation circuit 4, and a DTMF signal corresponding to the data is generated. This DTMF signal is amplified by the DTMF signal amplification circuit 5 and becomes a DTMF output signal of the dialer IC 9.

FIG. 6 is a block diagram of another conventional dialer IC. In this case, a microcomputer 10 is used to control key input, and the key input section la is a microcomputer 10. The dialer IC 9b is controlled via the interface circuit 2a.

[Problem to be solved by the invention]

In the above-mentioned conventional dialer IC, the magnitude of the DTMF output signal is determined by the DTMF signal generation circuit 4 and the DTMF signal amplification circuit 5, so whether it is sent out as a dial signal or as a data signal, However, the disadvantage is that their signal levels are the same.

For example, when sending a DTMF signal as data to a telephone connection destination in order to use an online service using a telephone line, the size of this DTMF signal is determined by the size of the DTMF signal sent as a dial signal for connection to the telephone line. The drawback is that only a signal of the same magnitude as the DTMF signal can be sent.

FIG. 7 is a simplified schematic diagram of this telephone line, in which 11 is a telephone on the data transmitting side, 12.1
3 represents a telephone office, 14 represents a data processing device including a telephone on the data receiving side, and I5 represents a telephone line (public line) network.

For example, enter the phone number of the person receiving the data as "0123J".
, the data to be transmitted is 144 #J. First, the transmitting side sends ro 123J to the telephone office 12 as a dial signal. Based on this dial signal, a telephone line is connected to the receiving side telephone 14 via the telephone line (public line) network 15 and telephone office 13.

After the transmitting side confirms that the receiving side is connected by some signal, it sends out a DTMF signal corresponding to data "+4#". The state of the DTMF signal at this time is shown in FIG.

The dial signal is required at the central office to which the transmitter is connected, whereas the data signal is required at the receiver to which it is ultimately connected.

For this reason, even though the signal transmission distance and the device that receives the signal (the exchange in the case of the telephone office 12 and the data processing device in the case of the receiving side 14) are different, the size of the DTMF signal sent from the sending side is different. is the same regardless of whether it is a dial signal or a data signal, so reception of the data signal on the receiving side may be incomplete due to transmission loss or the like.

An object of the present invention is to solve such problems by providing a dialer IC that can reliably receive data signals by changing the magnitude of the DTMF signal when transmitting dial signals and data signals. It is about providing.

[Means to solve the problem]

The configuration of the dialer IC of the present invention includes an interface circuit that detects key input from the key input section of a telephone, an input/output control circuit that controls signals between this interface circuit, and an input/output control circuit that controls signals between the input and output control circuits. a DTMF signal generation circuit that generates a DTMF signal corresponding to data;
It has a DTMF signal amplification circuit that amplifies the DTMF signal from the DTMF signal generation circuit, and a signal level switching circuit that switches the magnitude of the signal level of the DTMF signal according to the signal level switching signal from the input/output control circuit. It is characterized by

〔Example〕 Next, the present invention will be explained with reference to the drawings.

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

The present embodiment differs from the conventional example in that a signal level switching circuit 6 is added to the input side of the DTMF signal amplification circuit 5.

First, when the telephone number of the receiving party is input through the key input section 1, it is detected by the key interface circuit 2, and data corresponding to the key input is sent to the input/output control circuit 3. The input/output control circuit 3 sends the data to the DTMF signal generation circuit 4, and a DTMF signal corresponding to the data is generated. At this time, the signal level switching circuit 6 is connected to the a side where the resistor R1 is inserted by the signal level switching signal.

Therefore, after the DTMF signal is attenuated by the resistor R1,
The signal is amplified by the DTMF signal amplification circuit 5 and sent out as a dial signal.

Next, after the receiving side is connected, use the key input section l to send the DTM
When the "data" key is input as an input for switching the magnitude of the F signal, this input causes the input/output control circuit 3 to output a signal level switching signal, operate the signal level switching circuit 6, and switch to the b side. Connected. Here, when data is input from the key input section l, the DT
The MF signal generation circuit 4 generates a DTMF signal corresponding to a key input, but this signal does not pass through the resistor R1 and is directly input to the DTMF signal amplification circuit 5, so the dialer
The DTMF output signal (data signal) output from the IC has a higher level than the dial signal. Enter the recipient's phone number as 0123J Data to be sent r+4:
EFJ, the DTMF signal level increases on the data signal side B, as shown in FIG.

FIG. 3 shows the second embodiment of the present invention. FIG. 2 is a block diagram of an embodiment. In this embodiment, an attenuator 8 is inserted after the DTMF signal amplification circuit 5, and the signal level switching signal allows
The output of attenuator 8 is being switched. This example is
By outputting the connecting point of the resistors R2 and R3 in the attenuator 8 to the outside as an output terminal, the signal is attenuated by a division ratio determined by R2 and R-. Therefore, if the level difference between the dial signal and the data signal is insufficient, there is an advantage that the level difference can be adjusted by further connecting the resistor R4 between this terminal and the ground.

FIG. 4 is a block diagram of a third embodiment of the present invention, which is applied to the conventional example shown in FIG. 6 in the same way as FIG. 3. Therefore, the only difference is that a microcomputer IO and its interface circuit 2a are added to the key interface circuit 0+1), and that the attenuator 8a circuit is a multi-switching circuit.

〔Effect of the invention〕

As explained above, the present invention changes the magnitude of the DTMF signal when transmitting the dial signal and the data signal by switching the output level of the signal level switching circuit using the signal level switching signal from the input/output control circuit. is,
This has the effect that data signals can be transmitted at a sufficient signal level on the receiving side.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the first embodiment of the present invention, FIG. 2 is a waveform diagram of the output signal of FIG. 1, and FIGS. 3 and 4 are diagrams of the second and third embodiments of the present invention. Block diagrams, Figures 5 and 6 are block diagrams of two types of conventional dialer ICs, Figure 7 is a schematic diagram showing a general telephone line, and Figure 8 is the waveform of the output signal in Figure 5. It is a diagram. 1, la...key input section, 2...key interface circuit, 2a...interface circuit, 3...input/output control circuit, 4...・
...DTMF signal generation circuit, 5...DTMF signal amplification circuit, 6...Signal level switching circuit, 7
...Signal level switching signal, 8.8a...
...Attenuator, 9.9a, 9b...Dialer IC, 10...Microcomputer, R
, -R4...Resistor, 11...Data transmitting side telephone, 12.13...Telephone office (terminal station),
14... Data receiving side telephone and data processing device, 15... Telephone line (public line) network.

Claims (1)

[Claims] An interface circuit that detects key input from a key input section of a telephone; an input/output control circuit that controls signals between this interface circuit; and a DTMF signal that generates a DTMF signal corresponding to input data from this input/output control circuit. DT
an MF signal generation circuit, a DTMF signal amplification circuit that amplifies the DTMF signal from the DTMF signal generation circuit, and a signal level switch that switches the signal level of the DTMF signal according to a signal level switch signal from the input/output control circuit. 1. An integrated circuit for dialing a telephone, characterized in that it has a circuit.