JPH01137868A - Off-hook detecting means for equipment attached to telephone set - Google Patents

Abstract

PURPOSE:To suppress the mixture of a noise to a calling current to a minimum at the section of a relay coil part by applying the calling current of a telephone set at a normal time to a bypass route consisting of a switch connected to the relay coil part of an off-hook detecting circuit in parallel. CONSTITUTION:A switch 10 is provided which forms the bypass route of the calling current in parallel to a relay coil part 8, the conduction of the calling current to the relay coil part 8 is prevented at the normal time of using a telephone set, and the bypass route is used as a calling current route. That is, when a relay contact point is 11 closed and the calling current is detected to flow, since the telephone set is used, the switch 10 is immediately closed, the bypass route is conducted again, the conduction of the calling current to the coil part 8 is prohibited, and the noise mixture to the telephone line is effectively prevented.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention relates to an off-hook detection method for equipment attached to a telephone, and particularly to a method for detecting an idle state of a telephone line when dialing a data communication device attached to a telephone. This invention relates to an off-hook detection method for telephone accessory equipment.

(Conventional technology) In recent years, with the diversification and sophistication of user needs, the human world 1
By connecting 11 databases, a central host computer, and high-performance terminals via a network, we can issue train tickets, airline tickets, etc., search for patents or technical information, search for information on newspaper articles, product information, and tourism. Data communication services that provide information, manage sales inventory, etc. are available.

Large-scale data communication services that constantly handle large amounts of data use dedicated lines and terminals with advanced functions, but small-scale data communication services use public lines that are subscribed telephone networks. You can receive various services using a telephone equipped with a simple data communication function.

When connecting a data communications device with an automatic dialing function to a telephone line that is originally intended for use with a telephone, make sure that the data communications device does not start dialing while the telephone is in use and interfere with the call. It is necessary to take measures against this.

For this reason, this type of data communication device generally has an off-hook detection circuit interposed in series between the telephone and the telephone line to detect whether or not the handset is on the telephone, that is, whether or not a call is in progress. has been done.

This off-hook detection is normally realized by determining whether or not the telephone is in use based on the presence or absence of a talking current flowing through the telephone line.

That is, if a current detection element such as a photocoupler is inserted in series on one side of a pair of telephone lines, and a call signal is output based on the detection signal from the detection element, during that time,
Dialing out of data communication devices is prohibited to prevent call interference.

In this conventional off-footer detection method, a part of the current detection element is inserted in series with the telephone line itself, making it possible to accurately detect the 5 call current. When a non-conducting breakdown occurs, the telephone line is also cut off at the same time, causing a problem in which not only the data communication device but also the telephone becomes unusable.

Therefore, when particularly high reliability is required, for example when a third party installs data communication equipment to provide additional services to telephone users, photocoupler etc. Since the non-conductive breakdown of the detection element has a large effect, a relay winding or the like having a large capacity for large currents is used as the current detection element.

However, when using a relay winding, the relay winding is connected in series to one of the pair of telephone lines, so when using the telephone, a small amount of noise may be mixed into the telephone line, causing the sound during one call to be There was a problem in that the quality of the products deteriorated to some extent. This noise is thought to be caused by unnecessary voltage generated in the coil by the magnetic field around the coil.

(Object of the Invention) In order to achieve the above object, the off-hook detection method for a telephone accessory device of the present invention connects a relay winding part in series to one side of a telephone line, so that when a data communication device makes a dial call, In an off-hook detection method for a telephone accessory device that detects the presence or absence of talk current to determine whether or not a data communication device can operate, the relay winding section is normally closed by short-circuiting the relay winding section with a bypass switch. This effectively prevents noise from entering the phone by bypassing it, and checks whether the phone line is free (whether a call is in progress) or not just before the data communication device starts dialing.
In order to detect this, the bypass switch is opened to make the relay winding part conductive to detect the call current, and if the call current is not detected, the telephone line is switched to the data transmitting/receiving part. .

(Example) The off-footer detection method for a telephone accessory device according to the present invention will be described in detail below with reference to one drawing.

FIG. 1 shows a block circuit diagram to which the method of the present invention is applied,
A data communication device 3 is interposed between the telephone set 1 and a pair of telephone lines 2. The data communication device 3 includes an off-hook detection circuit 4 for detecting an idle state of a telephone line, a data transmission/reception unit 5 for realizing an information transmission function between a host computer (not shown), and a data transmission/reception unit 5 for transmitting/receiving data to/from the telephone 1. relay contacts 6, 7 inserted in series with each telephone line for selective switching with section 5.

The off-hook detection circuit 4 includes a relay winding section 8 connected in series to one side of the telephone line 2, a bypass capacitor 9 connected in series to the relay winding section 8, and a relay winding section 8.
and a switch IO connected in parallel to the bypass capacitor 9, respectively. The bypass capacitor 9 bypasses the audio signal so that it is not attenuated by the relay winding section 8. The switch 10 bypasses the relay winding section 8 by closing when the telephone is in use, and opens for a short time to detect whether or not the telephone is in use prior to starting dialing. It is a part that performs a characteristic function.

The data transmitting/receiving section 5 is provided with a relay contact 11 that closes when a communication current is detected in the relay winding section 8 .

The gist of the method of the present invention is that a bypass path including another switch IO is formed in the off-footer detection circuit 4, and the communication current during normal use of the telephone is configured to flow through this bypass path, and the circuit is connected in series to the telephone line. By connecting to the relay winding section 8 only when detecting the communication current, it is possible to minimize noise mixing into the communication current through the relay winding.

The operation of the method of the present invention will be explained in the above configuration.

Connection switching between the telephone 1 and the data transmitting/receiving unit 5 is performed by relay contacts 6 and 7 disposed inside the data communication device 3 and connected in series to each of a pair of telephone lines. When is in the solid line position as shown in the figure, the telephone 1 and the telephone line 2 are connected and a conversation is possible.

On the other hand, when the relay contact 6.7 is switched to the dotted line position, the telephone 1 is disconnected, the telephone line and the data transmitting/receiving section 5 are connected, and data communication 3 using the telephone line becomes possible.

Note that, unlike the conventional off-hook detection circuit, the switch 10
If the configuration is such that the relay contacts 6 and 7 are connected to the solid line side and the telephone is off-hook, a communication current will flow, and the relay winding part 8 inserted in series on one side of the telephone line 2 will flow. As mentioned above, there is a problem that noise generated by the method is mixed in.

In order to solve this problem, in the method of the present invention, a switch 10 is newly provided in parallel with the relay winding section 8 to form a bypass path for the communication current.

During normal use of the telephone, the communication current is turned off to the relay winding section 8 so that the bypass path is used as the communication current path.

That is, when the relay contacts 6.7 are switched to the dotted line side in FIG. 1 and the data transmitting/receiving section 5 starts data communication, it is determined whether there is a communication current before starting data communication. At this time, first, by opening the switch 10, the bypass path is made non-conductive in terms of direct current, and at the same time, the relay winding section 8 is made conductive, and the relay contact 11 provided in the data transmitting/receiving section 5 is opened and closed. Detects the presence or absence of call current.

That is, if it is determined that the relay contact +1 is closed and the communication current is flowing, the telephone is in use, so the switch 10 is immediately closed to make the bypass path conductive again and to connect the winding 8 to the telephone. By prohibiting communication current from flowing, it is possible to effectively prevent noise from entering the telephone line.

Next, when it is determined that the telephone is not in use due to the opening of the relay contact 11, the relay contacts 6, 7 are switched to the contact side, the data transmitting/receiving section 5 is connected to the telephone line 2, and predetermined information communication is performed. , after the operating path f, the relay contact 6.7 is returned to the solid line side. During this time, telephone 1 is disconnected from telephone line 2.

According to the method of the present invention, the reliability of the device can be improved when a data communication device is installed to share the telephone line of the telephone in order for a third party to provide other data communication services to the telephone user. be able to.

(Effects of the Invention) As explained above, according to the off-footer detection method for a telephone accessory device of the present invention, the switch is configured to connect the telephone communication current of the telephone in parallel with the relay winding of the off-hook detection circuit. By allowing the current to flow through the bypass path, noise mixing into the communication current due to the relay winding can be minimized.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram to which the method of the present invention is applied. DESCRIPTION OF SYMBOLS 1...Telephone 2...Telephone line 3...Data communication device 4...Off-hook detection circuit 5...Data transmitting/receiving section 6.7...Relay contact 8...Relay winding section 9.・
・Bypass capacitor 10...Switch patent applicant
Toyo Tsushinki Co., Ltd.

Claims (1)

[Claims] Before starting automatic dialing of a data communication device that shares a pair of telephone lines with a telephone, a relay winding section connected in series with one of the telephone lines detects the presence or absence of talk current of the telephone. In a method for detecting off-hook of a telephone accessory device for determining whether or not a data communication device is operational, a bypass switch is provided in parallel with the relay winding section, and when the telephone is making a normal call, the switch is closed and a call current is supplied to the bypass switch. off-hook of telephone accessory equipment, characterized in that the presence or absence of a talking current is detected by opening the switch and putting the relay winding section into a driveable state only immediately before the automatic dialing of the data communication device starts. Detection method.