JPH04117797A - Electronic circuit - Google Patents

Abstract

PURPOSE:To simply detect and discriminate a call signal from a line and the polarity inversion of the line simultaneously by inserting two photocouplers connected in series to the line. CONSTITUTION:Two photocouplers 7, 8 are inserted in series to lines 3, 4 respectively and the one is used to detect only a call signal from the line and the other is used to detect the polarity inversion and the arrival of the call signal of the like. The two detected signals are inputted to a controller on an electronic device and processed therein, them the call signal and the polarity inversion are discriminated. Thus, the electronic circuit is used for a call signal detection circuit and a polarity detection circuit simply at a low cost.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to electronic circuits in electronic devices having terminal equipment.

[Summary of the Invention] A circuit is provided for simultaneously and easily detecting and discriminating a calling signal from a line and a polarity reversal of the line by inserting at least two photocouplers in series with the line.

[Prior Art] Conventionally, in electronic equipment with terminal equipment, two photocouplers have been connected in parallel in order to detect and distinguish a call signal from a line and a polarity reversal of the line (see Figure 2 (Transistor Technology 1985). (See page 407 of November issue)
, a circuit for detecting a call signal and a circuit for detecting polarity reversal were provided separately. To explain using the example in Figure 2, when the switch in Figure 2 (10B) is turned to the a side, the circuit in Figure 2 works as a call signal detection circuit, and when it is turned to the b side, it works as a polarity reversal detection circuit. Ta.

In addition, in a call signal detection circuit using one photocoupler, by selecting the time constant of the internal circuit (resistor 9, capacitor 10 in Figure 1), it is possible to detect the call signal and polarity reversal, but they are detected indistinguishably. The problem was that it could not be determined.

[What the invention aims to solve] As mentioned above, in order to detect and distinguish between the call signal from the line and the polarity reversal of the line using the conventional technology, it is necessary to switch the detection circuit, and the electronic equipment This has become an obstacle to simplifying circuits as they become more sophisticated and more compact. Further, the signal detection circuit and the polarity reversal detection circuit are separately provided and switched by a switch, which increases the cost.

The present invention has been made to solve these problems, and an object of the present invention is to provide a simple, low-cost electronic circuit that functions as both a signal detection circuit and a polarity reversal detection circuit.

[Means for Solving the Problems] The electronic circuit of the present invention is an electronic device having terminal equipment, in which at least two photocouplers are connected in series in order to detect and discriminate a calling signal from a line and polarity reversal of the line. It is characterized by

[Function] According to the configuration of the present invention, by inserting two photocouplers in series in the line, one detects only the calling signal from the line, and the other detects the polarity reversal of the line and the calling signal. It has become. These two detected signals are taken into a controller on the electronic device and processed, thereby distinguishing between a call signal and polarity reversal.

As described in the prior art, in a call signal detection circuit using one photocoupler, by selecting the time constant of the internal circuit, the time constant of the circuit that can detect the call signal and polarity reversal without distinction (see Fig. 1, resistor 9 , the time constant of the capacitor 11, the time constant of the resistor 13, and the time constant of the capacitor 12), a circuit that can detect only the calling signal can be constructed. The electronic circuit of the present invention utilizes this characteristic.

Embodiment J An embodiment of the present invention is shown in FIG. 1(a), and an example of the operation of the embodiment is shown in FIG. 1(b). The present invention will be described in detail with reference to FIG.

1(a) 7 is a photocoupler for detecting a calling signal, and FIG. 1(a) 8 is a photocoupler for detecting a calling signal and polarity reversal detection (this photocoupler is bipolar). An example of the waveform output in FIG. 1(a)l is 20 in FIG. 1(b), and an example of the waveform output in FIG. 1(a)2 is 21 in FIG. 1(b). This example is a waveform example when a call from the line is detected based on two waveforms. Waveform 20 and waveform 21 are input to a controller of an electronic device. The controller can determine the current line state by comparing the waveform pattern with the waveform pattern inside the controller.

Figure 3 shows a routine for determining the calling signal and polarity reversal. Input waveform 1 and input waveform 2 are compared, and if it is determined that the same waveform has been input, it is determined that it is a calling signal, and input waveform 1 is determined to be the calling signal.
If only is input, it is determined that the polarity is inverted. The controller determines the calling signal and the polarity inversion signal using the above routine, and then determines the state of the line based on how the calling signal and the polarity inversion signal are input.

[Effects of the Invention] As described above, according to the present invention, it is possible to provide an electronic circuit that is simple and inexpensive and has both a calling signal detection circuit and a polarity reversal detection circuit. Therefore, when a plurality of terminal devices are connected to one line, it can be determined whether the line is in use or not, and confusion in line use can be avoided.

[Brief explanation of the drawing]

FIGS. 1(a) and 1(b) are diagrams showing an embodiment of the present invention. FIG. 2 is a diagram showing a conventional embodiment. Figure 3 is a flowchart for determining call signal detection and polarity reversal detection.・ ・ 5 ・ ・ ・ ・ ・ ・ Calling signal detection and polarity reversal detection Calling signal detection and polarity reversal detection Calling signal detection Calling signal detection and polarity reversal detection Line Line Electronic equipment power supply (+) 6...Electronic equipment type m (-) 7...Photocoupler 8...Photocoupler 9.10.13.14.18.101.102.103
．． 106.107...1. Resistor 11.12.15.105...Capacitor 16, 17
・ ・ ・・・・・・ ・Diode 104...
Barista 109.110...Buffer IC20...
... Calling signal and polarity reversal detection waveform 21 ... Calling signal detection waveform 22 ... Polarity reversal detection waveform 23 ... Calling signal detection waveform 3o ... Input of waveform 1 and waveform 2 31...Comparison of waveform 1 and waveform 2 32...Polarity reversal detection 33...Call signal detection and above Requester Seiko Epson Co., Ltd. Agent Patent attorney Suzufuki Sanbe (1 person) (b) Figure 1, Figure 20

Claims (1)

[Claims] 1. An electronic device having terminal equipment, characterized in that at least two photocouplers are connected in series in order to detect and discriminate a call signal from a line and a polarity reversal of the line.