JPH0420162A - Data terminal equipment - Google Patents

Abstract

PURPOSE:To incorporate an exchange function simply at a low cost to a terminal equipment by connecting an exchange means comprising a switch means connecting/interrupting a line in series and a control means controlling the switch means based on a current flowing to the line between the line and a data terminal equipment and between the line and a connection terminal respectively. CONSTITUTION:An exchange circuit detects on-hook and off-hook of a data terminal equipment 4 and acts like an exchange 2 between other data terminal equipments 6, 8. When one of the data terminal equipments 6, 8, 4 is hooked off in this way, the exchange circuit 2 of the line is turned on and even when other data terminal equipments 6, 8 are hooked off, the exchange circuit 2 of the line is kept off. However, when the data terminal equipments 4 whose exchange circuit 2 is turned on is hooked off, the exchange circuits 5, 7 of the data terminal equipments 6, 8 hooked off later are turned on. Thus, the exchange function is incorporated in the data terminal equipment simply at a low cost.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a data terminal device that can be connected to a public telephone line.

[Conventional technology] Conventionally, when a single telephone number was shared by multiple data devices, the data devices were connected to the line in parallel.

[Problem to be solved by the invention] In the conventional connection method, if one data terminal device puts another data terminal device into the 0FF-HOOK state while communicating, the communication data may be destroyed or leaked. was there.

To incorporate a general commercial exchange into a data terminal device,
Since it is a complex circuit, it is expensive and occupies a large area.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention provides a data terminal device with an exchange function configured as shown in FIG. 1. The first circuit shown is 0N of data terminal equipment.
-Detects HOOK and 0FF-800K and acts as an exchange with other data terminal equipment.

[Operation] When one of the data terminal devices is set to 0FF-HOOK,
The switching circuit of that line will be in the ON state, and even if other data terminal equipment is set to 0FF-HOOK, the switching circuit of that line will remain in the OFF state. However, the exchange circuit is ON
If you set the current data terminal device to 0N-HOOK, the exchange circuit of the data terminal device that was later set to 0FF-800K will be in the ON state.

[Example] Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, the main terminal device 4 is set to 0FF-HOO
Make it K. The current supplied from the telephone line 1 flows through the reverse connection prevention diode bridge 3, operates the constant voltage diodes 13 and 16, which are control means, and flows through the resistor 14.

At that time, the voltage of the resistor 14 is charged to the capacitor 15, and the SIRISK 10, which is a switching means, is operated.

The current flowing through the SIRISK 10 is limited by the resistor 11, causing the selected line display light emitting diode 12 to emit light, and the terminal device 4 is connected to the telephone #! connected to l. In this state, turn the data terminal device connected to connector 6 to 0FF-HO.
Even if it is OK, since the voltage of the telephone line 1 is low, the constant voltage diode 22, which is the control means of the exchange circuit 5, does not operate, so the thyristor 19, which is the switch means, also does not operate. Therefore, almost no current is supplied to the data terminal device connected to the connector 6, so it is not connected to the telephone line.However, the data terminal device 4 is set to 0FF-HO.
If OK is selected, the current supply from the telephone line 1 to the main data terminal device 4 is cut off, and current flows through the reverse connection prevention diode bridge 18, operating the constant voltage diodes 22 and 25, which are the control means, and the resistor 23. flows. At that time,
The voltage across resistor 23 charges capacitor 24 and operates thyristor 19. Thyristor 1 as a switching means
The current flowing through the terminal 9 is restricted by the resistor 20, causing the selected line indicating light emitting diode 21 to emit light, and the terminal device connected to the connector 6 is connected to the telephone line 1. At this time resistance 1
7 has the function of lowering the impedance on the terminal side and stabilizing the closed loop of the telephone line 1. Also, since the three exchange circuits 2, 5 and 7 are similar circuits, 0N-HOOK
The first and second data terminals that are used operate in the same manner as described above.

Also, after setting the main terminal device 4 to 0FF-HOOK,
Connect the data terminal equipment connected to connectors 6 and 8 to 0F.
If you set it to F-HOOK, the terminal device 4 will be set to 0N-HOOK.
When set to K, the exchange circuit with the higher voltage of capacitor 24 or 26 becomes active.Priority can be easily assigned by the charging time constant of the resistor and capacitor.The larger the time constant, the higher the priority. , and any initial data terminal equipment operates in the same manner as described above.

[Advantageous Effects of the Invention 1] As described above, the present invention makes it possible to incorporate an exchange function into a data terminal device, which has conventionally been inconvenient but could not be easily realized at low cost.

Furthermore, by making the output from the exchange circuit a modular jack, users can easily connect data to terminal equipment with only one wire.
It has become possible to use a single telephone line more effectively.

[Brief explanation of the drawing]

FIG. 1 shows a switching circuit built into the data terminal device of the present invention. 1 ・ 2 ・ 3 ・ 4 ・ 5 ・ 6 ・ 7 ・ 8 ・ 9 ・ 10 ・ 11 ・ l 2 ・ 13 ・ 14 ・ ・Telephone line・Switching circuit・Diode bridge・Main terminal device・Switching circuit・Connecting end・Replacement circuit/connection end/resistance/silisk/resistance/light emitting diode/constant voltage diode resistance 15 ・ 16 ・ 17 ・ 18 ・ l 9 ・ 20 ・ 2 l ・ 22 ・ 23 ・ 24 ・ 25 ・ 26 ・ ... Capacitor constant voltage Diodes, Resistors, Diode Bridges, Silisk, Resistors, Light Emitting Diodes, Constant Voltage Diodes, Resistors, Capacitors, Constant Voltage Diodes, Capacitors Applicant Seiko Electronics Co., Ltd. Agent Patent Attorney Takayuki Hayashi Bokeku ■ Mouth

Claims (1)

[Claims] In addition to the main data terminal device to which lines from the outside are connected, the data terminal device has means for distributing lines in parallel and has a connection end to which at least one other data terminal device can be connected, Exchange means consisting of switching means for connecting and disconnecting the line and control means for controlling the switching means based on the current flowing through the line are connected in series between the line and the data terminal device, and between the line and the connection end. A data terminal device characterized by: