JPH07107522A - Extended device for exchange device - Google Patents

Abstract

PURPOSE:To surely stop power supply by preventing a current from another device when an internal power source is turned off. CONSTITUTION:At an extended beam C, a tristate buffer circuit 5 is positioned between a transmission buffer circuit 2 of a basic beam A and a reception buffer circuit 4 of the extended beam C. Since a voltage VE outputted from an extended beam power supply circuit 3 is compared with a voltage, which is provided by dividing a voltage VB outputted from a basic beam power supply circuit 1 at resistors R1 and R2, by a comparator 6, it is detected that only the voltage VE is extremely lowered and in this case, a signal output to the reception buffer circuit 4 is cut off by turning the tristate buffer circuit 5 to a high impedance state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an expansion device for expanding a switching device such as a key telephone device.

[0002]

2. Description of the Related Art In a switching device such as a key telephone device, for example, a basic function as a switching device is provided in order to flexibly expand the line capacity and the like and to make the device scale according to the needs of the user. The main structure is a relatively small-scale basic rack having at least a specific function, and an expansion rack having a partial function is attached as needed.

FIG. 3 is a diagram showing a configuration example of such a key telephone device. In the figure, A is the basic rack, B (B-1 to Bn)
Is an extension rack. The basic rack A includes a basic rack power supply circuit 1 and a transmission buffer circuit 2 (2-1 to 2-n). The basic rack power supply circuit 1 has a power switch 11, a transformer 12, a regulator circuit 13 and a photocoupler 14, and generates a voltage V _B to be supplied to each part of the basic rack A and each expansion rack B. The transmission buffer circuit 2 corresponds to each of the extension racks B and outputs a control signal given to the corresponding extension rack B. Reference numeral 15 is a short plug attached to the basic rack power supply circuit 1.

The extension racks B each include an extension rack power supply circuit 3 and a reception buffer circuit 4. The extension rack power supply circuit 3 includes a power switch 31, a transformer 32, a regulator circuit 33, and a photocoupler 34, and supplies a voltage V _E (V _E1 ~
V _En ) is generated. The reception buffer circuit 4 receives the control signal output from the basic rack A.

The power of the extension rack B can be independently turned off by the power switch 31. As a result, the other extension racks B can be operated and the specific extension rack B can be operated.
It is possible to perform maintenance and inspections of.

Incidentally, the transmission buffer circuit 2 of the basic rack A
Is a p-channel MOS FET2a as shown in FIG.
And an n-channel MOS FET 2b. As shown in FIG. 4, the reception buffer circuit 4 of the extension rack B is composed of a p-channel MOS FET 4a, an n-channel MOS FET 4b and parasitic diodes 4c and 4d.

Therefore, when only the extension rack power supply circuit 3 of a certain extension rack B is turned off, when the "High" level is output from the transmission buffer circuit 2 of the basic rack A, the power supply line of V _B Current flows from the power supply line to V _E through the MOS FET 2a and the parasitic diode 4d. That is, power is supplied into the extension rack B even though the extension power supply circuit 3 is not operating, and maintenance and inspection cannot be performed. Further, since power is supplied to each part of the extension rack B, the extension rack B may malfunction.

[0008]

As described above, the prior art is as follows.
Even if the power of the expansion device (expansion rack) is turned off, the signal supplied from the basic device (basic rack) to the expansion device spills into the power line of the expansion device, which causes power supply to the expansion device. there were.

The present invention has been made in consideration of such circumstances, and an object of the present invention is to prevent a current from sneaking from another device when the internal power supply is turned off. An object of the present invention is to provide an expansion device for a switching device that can reliably cut off supply.

[0010]

In order to achieve the above object, the present invention provides an expansion device power supply means such as an expansion power supply circuit for supplying electric power into an expansion device such as an expansion rack. Receiving means such as a receiving buffer circuit for receiving a predetermined signal such as a control signal, which operates from the power supplied from the expansion device power supply means and is sent from a basic device such as a basic rack, and the basic device. It operates on the power supplied from the basic device power supply means such as a basic rack power supply circuit provided in the device, and for example, a trie inserted between the basic device and the receiving means in the transmission path of the predetermined signal. A tristate buffer means such as a state buffer circuit and a tristate buffer control means including, for example, a comparator and two resistors are provided. The output state of the expansion device power supply unit is monitored by tristate buffer control means, and the output of the tristate buffer means in response to the output has gone to a high impedance state.

[0011]

By taking such means, the tri-state buffer means operated by the power output from the basic device power supply means of the basic device is in a high impedance state when the expansion device power supply means stops outputting power. By this, the receiving means that is operated by the electric power supplied from the expansion device power supply means from the basic device is electrically separated.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a main configuration of a key telephone device configured by applying the expansion device according to the present embodiment.
The same parts as those in FIG. 3 are designated by the same reference numerals.

This key telephone system comprises a basic rack A and at least one (n in the figure) expansion rack C (C-1 to Cn). The basic rack A has a power switch 11 and a transformer 1.
2, a basic rack power supply circuit 1 having a regulator circuit 13 and a photocoupler 14, and a transmission buffer circuit 2 (2-1 to
2-n) and.

The power switch 11 is inserted between the commercial power supply and the transformer 12, and turns on / off the application of the commercial power supply voltage to the transformer 12. The transformer 12 has a commercial power supply connected to the primary side and a regulator circuit 13 connected to the secondary side, separates the commercial power supply side from the regulator circuit 13 side, and transforms the commercial power supply voltage into a predetermined voltage. And supplies it to the regulator circuit 13.

The regulator circuit 13 rectifies the voltage (AC voltage) given from the transformer 12 and controls the switching, so that a voltage V _B (DC) of a predetermined voltage value is obtained.
Voltage).

The photocoupler 14 is a photodiode 1
4a and phototransistor 14b. The collector of the phototransistor 14b is the regulator circuit 13
Is connected to the grounding terminal and the emitter is grounded. Therefore, the photocoupler 14 grounds the ground terminal of the regulator circuit 13 when turned on. However, the phototransistor 14b is short-circuited by the short plug 15, and the grounding terminal of the regulator circuit 13 is always grounded.

The transmission buffer circuits 2 are provided in a number (here, n) corresponding to the maximum number of expandable racks C that can be mounted. The transmission buffer circuit 2 sends a control signal given from another circuit (not shown) in the basic rack A to the corresponding expansion rack C.

On the other hand, the extension rack C includes an extension rack power supply circuit 3 having a power switch 31, a transformer 32, a regulator circuit 33, and a photocoupler 34, a reception buffer circuit 4, a tristate buffer circuit 5, and a comparator 6. And resistors R ₁ and R ₂ .

The power switch 31 is inserted between the commercial power supply and the transformer 32, and turns on / off the application of the commercial power supply voltage to the transformer 32. The transformer 32 has a primary side connected to a commercial power source and a secondary side connected to a regulator circuit 33, separates the commercial power source side from the regulator circuit 33 side, and transforms the commercial power source voltage into a predetermined voltage. And supplies it to the regulator circuit 33.

The regulator circuit 33 rectifies the voltage (AC voltage) given from the transformer 32 and controls the switching so that the voltage V _E (V _E1 ) of a predetermined voltage value.
~ V _En ).

The photocoupler 34 includes the photodiode 3
4a and phototransistor 34b. In the photodiode 34a, the voltage V _B generated by the basic power supply circuit 1 is applied to the anode, and the cathode is grounded. The collector of the phototransistor 34b is connected to the ground terminal of the regulator circuit 33, and the emitter is grounded. Therefore, the photocoupler 34 is turned on when the basic rack power supply circuit 1 is outputting a voltage of V _B , and the grounding terminal of the regulator circuit 33 is grounded at this time.

The reception buffer circuit 4 receives the control signal output from the basic rack A. The tri-state buffer circuit 5 is interposed between the transmission buffer circuit 2 and the reception buffer circuit 4, and operates by the voltage V _B generated by the basic rack power supply circuit 1.

The comparator 6 divides the voltage V _E generated by the extension rack power supply circuit 3 of the extension rack C to which it belongs and the voltage V _B generated by the basic rack power supply circuit 1 by resistors R ₁ and R ₂ . Compare with voltage. The comparator 6 operates with the voltage V _B generated by the basic rack power supply circuit 1.

FIG. 2 is a diagram showing a specific configuration and connection state of the transmission buffer circuit 2, the reception buffer circuit 4, the tri-state buffer circuit 5 and the comparator 6.
The transmission buffer circuit 2 is a p-channel MOS FET2.
It is composed of a and an n-channel MOS FET 2b. MO
Control signals are input to the gate of the S FET 2a and the gate of the MOS FET 2b, respectively. The voltage V _B generated by the basic rack power supply circuit 1 is applied to the source and back gate of the MOS FET 2a. The source and back gate of the MOS FET 2b are grounded. MOS FET2
The drain of a and the drain of the MOS FET 2b are connected to each other. In addition, MOS FET2a and MO
The drain of the SFET 2b is connected to the connection line between the basic rack A and the extension rack C.

The tri-state buffer circuit 5 includes a p-channel MOS FET 5a and an n-channel MOS FE.
It includes T5b, parasitic diodes 5c and 5d, and a switch element 5e. Gate of MOS FET5a, MOS
The gate of the FET 5b, the cathode of the parasitic diode 5c and the anode of the parasitic diode 5d are connected to the connection line between the basic rack A and the extension rack C, respectively. MOS
The voltage V _B generated by the basic rack power supply circuit 1 is applied to the source and back gate of the FET 5a. The source and back gate of the MOS FET 5b are grounded. The drain of the MOS FET 5a and the drain of the MOS FET 5b are connected to each other. Also, the MOS FET 5a and the MOS FE
The drain of T5b is connected to one end of the switch element 5e. The anode of the parasitic diode 5c is grounded. The voltage V _B generated by the basic rack power supply circuit 1 is applied to the cathode of the parasitic diode 5d. The reception buffer 4 is connected to the other end of the switch element 5e. The switch element 5e is turned on / off by the output of the comparator 6.

The receive buffer circuit 4 is a p-channel MO
It is composed of an S FET 4a, an n-channel MOS FET 4b and parasitic diodes 4c and 4d. MOS FET
The gate of 4a, the gate of the MOS FET 4b, the cathode of the parasitic diode 4c, and the anode of the parasitic diode 4d are connected to one end of the switch element 5e of the tristate buffer circuit 5, respectively. MOS FET
The voltage V _E generated by the extended power supply circuit 3 is applied to the source and the back gate of 4a, respectively. MO
The source and back gate of the SFET 4b are grounded. Drain of MOS FET 4a and MO
The drain of the SFET 4b is connected to each other.
The drains of the MOS FETs 4a and 4b are connected to the output line of the control signal. The anode of the parasitic diode 4c is grounded. The voltage V _E generated by the extended power supply circuit 3 is applied to the cathode of the parasitic diode 4d.

At the non-inverting input terminal of the comparator 6, the voltage V _B generated by the basic rack power supply circuit 1 is applied to the resistors R ₁ and R _2.
The voltage obtained by voltage division is applied. The voltage V _E generated by the extended power supply circuit 3 is applied to the inverting input terminal of the comparator 6. The comparator 6 compares the voltage and the voltage V _E obtained by dividing the frequency by a resistor R _1, R ₂ voltage V _B, the voltage V _B resistor R _1, the R ₂ of the voltage obtained by dividing When it is larger, it outputs a "High" level signal.

Next, the operation of the key telephone device configured as described above will be described. First, when the power switch 11 of the basic rack power supply circuit 1 is turned on from the off state, the commercial power supply voltage is transformed into a predetermined voltage by the transformer 12 and then supplied to the regulator circuit 13. Regulator circuit 13
Is always in operation because the grounding terminal is always grounded by the shorting plug 15. Therefore, the regulator circuit 13 receives the voltage (AC voltage) from the transformer 12.
Is supplied, it is rectified and subjected to switching control to be converted into a voltage V _B (DC voltage) having a predetermined voltage value and output. The voltage V _B is supplied to each part in the basic rack A and the extension rack C, respectively.

When the voltage V _B is output from the basic rack power supply circuit 1, this voltage V _B is applied to the photodiode 34b, so that the photo coupler 34 is turned on. As a result, the ground terminal of the regulator circuit 33 is grounded,
The regulator circuit 33 is activated.

Here, the power switch 3 of the extension power circuit 3
1 is normally on. Therefore, the voltage is supplied from the transformer 32 to the regulator circuit 33. Therefore, the regulator circuit 13 rectifies the voltage (AC voltage) supplied from the transformer 12 and performs switching control to control the voltage V _E (DC voltage) of a predetermined voltage value.
And output. This voltage V _E is the voltage V _E output from the corresponding extension rack C (the extension rack power supply circuit 3 of the extension rack C-1).
_E1 is supplied to each part of the extension frame C-1 and the voltage V _En output from the extension frame power supply circuit 3 of the extension frame Cn).

When the basic rack power supply circuit 1 and each extended rack power supply circuit 3 output voltages in this way, the transmission buffer circuit 2, the reception buffer circuit 4, the tri-state buffer circuit 5 and the comparator 6 operate respectively. . Therefore, in this state, if a control signal is input to the transmission buffer circuit 2, this control signal is output from the transmission buffer circuit 2 to the corresponding extension rack C.

In each extension rack C, in the comparator 6, the extension rack power supply circuit 3 included in the same extension rack C is used.
Output voltage V _E (comparator 6 of extension rack C-1
Is the voltage V _E1 , and the comparator 6 of the extension rack Cn is the voltage V _En ).
And the voltage V _B output by the basic rack power supply circuit 1 is divided by the resistors R ₁ and R ₂ to obtain a voltage. Wherein the resistance value of the resistor R _1, R _2, in a state where the basic rack power supply circuit 1 and the expansion card power supply circuit 3 are both operating, by dividing the voltage V _B at the resistors R _1, R ₂ obtained The respective voltages are set to be slightly lower than the voltage V _E. This prevents the output of the comparator 6 from being at the “High” level even if some noise is superimposed on the voltage V _B or the voltage V _E.
Thus, the comparator 6 brings the output to the “High” level when only the voltage V _E is significantly lower than the level in the normal operating state. Specifically, when the power switch 31 of any of the extension racks C is turned off and the operation of the extension rack power supply circuit 3 of the extension rack C is stopped, the output of the comparator 6 is “High” accordingly. It becomes a level.

The switch element 5e of the tri-state buffer circuit 5 is in the ON state when the output of the comparator 6 is at the "Low" level. Therefore, if the control signal is output from the transmission buffer circuit 2 in this state, this control signal is given to the reception buffer circuit 4 via the tri-state buffer circuit 5 and received.

However, when the output of the comparator 6 is at the "High" level as described above, the switch element 5e of the tri-state buffer circuit 5 is turned off and the tri-state buffer circuit 5 is brought to a high impedance state. . That is, the tristate buffer circuit 5 in the extension rack C in which the operation of the extension rack power supply circuit 3 is stopped is brought into a high impedance state. Therefore, if the control signal is output from the transmission buffer circuit 2 in this state, the control signal is blocked by the tri-state buffer circuit 5 and is not output to the reception buffer circuit 4.

Thus, according to this embodiment, the control signal is not given to the reception buffer circuit 4 in the extension rack C in which the power switch 31 is turned off. Moreover, the tri-state buffer 5 operates at the voltage V _B output from the basic rack power supply circuit 1 and is not connected to the power supply line of V _E. Therefore, the control signal does not flow into the power supply line of V _E , maintenance and inspection of the extension rack C with the power switch 31 turned off can be performed, and the extension rack C with the power switch 31 turned off can be performed. Does not malfunction.

The present invention is not limited to the above embodiment. For example, in the above embodiment, the present invention is applied to the key telephone device, but it can also be applied to other exchange devices such as general telephone exchanges and private branch exchanges. In addition, various modifications can be made without departing from the scope of the present invention.

[0037]

According to the present invention, an expansion device power supply means such as an expansion power supply circuit for supplying electric power into an expansion device such as an expansion rack, and the power supplied from the expansion device power supply means. Receiving means such as a receiving buffer circuit for operating and receiving a predetermined signal such as a control signal transmitted from a basic device such as a basic rack, and a basic rack power supply circuit provided in the basic device, for example. And a tri-state buffer means such as a tri-state buffer circuit interposed between the basic device and the receiving means in the transmission path of the predetermined signal, which operates with electric power supplied from the basic device power supply means. , For example, a tri-state buffer control means including a comparator and two resistors is provided, and the tri-state buffer control means is The output state of the expansion device power supply means is monitored, and the output of the tri-state buffer means is set to a high impedance state in response to the loss of output, so that when the expansion device power supply means is turned off, It is possible to prevent the electric current from sneaking in from other devices and to cut off the power supply surely, which facilitates maintenance and inspection, and does not cause malfunction during maintenance and inspection. It becomes an expansion device.

[Brief description of drawings]

FIG. 1 is a diagram showing a main configuration of a key telephone device configured by applying an expansion device according to an embodiment of the present invention.

FIG. 2 is a diagram showing specific configurations and connection states of a transmission buffer circuit 2, a reception buffer circuit 4, a tri-state buffer circuit 5 and a comparator 6.

FIG. 3 is a diagram showing a main configuration of a conventional key telephone device.

FIG. 4 is a diagram showing specific configurations and connection states of a transmission buffer circuit 2 and a reception buffer circuit 4 in a conventional key telephone device.

[Explanation of symbols]

A ... Basic rack C (C-1 to Cn) ... Extended rack 1 ... Basic rack power supply circuit 2 (2-1 to 2-n) ... Transmission buffer circuit 3 ... Extended rack power supply circuit 4 ... Reception buffer circuit 5 ... Tristate Buffer circuit 6 ... Comparators R ₁ and R ₂ ... Resistors 11, 31 ... Power switch 12, 32 ... Transformer 13, 33 ... Regulator circuit 14, 34 ... Photo coupler 15 ... Short plug

Claims (1)

[Claims] 1. An expansion device, which is mounted on a switching device mainly composed of a basic device and operates based on a predetermined signal sent from the basic device to expand the function of the switching device, An expansion device power supply means for supplying electric power to the expansion device, a reception means for operating with the electric power supplied from the expansion device power supply means, and receiving the predetermined signal, and provided in the basic device. And the output of the expansion device power supply means, which operates on the electric power supplied from the basic device power supply means and is inserted between the basic device and the receiving means in the transmission path of the predetermined signal. And a tristate buffer control means for monitoring the state and setting the output of the tristate buffer means to a high impedance state when the output is exhausted. Expansion device for replacement and wherein the door.