JPH071879Y2 - Button telephone device response detection circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a button telephone device, and more particularly to a response detection circuit of each telephone connected to a main device.

(Prior Art) An example of a conventional key telephone device will be described with reference to FIG. Here, in particular, the main device 1'and a single telephone set 2 connected to the main device 1'via the call current supply lines L ₁ and L ₂ are shown. Further, the main unit 1'shows a circuit for sending a calling signal and a circuit for detecting a response of the telephone set 2.

In the telephone 2, a ring tone generation circuit 4 is provided between the communication network 5 and the communication current supply lines L ₁ and L ₂ via a capacitor C ₁ and a hook switch HS.

In the ringing signal transmission circuit 6, reference numeral 8 is an oscillator for generating a low-voltage low-frequency pulse having the same frequency of 16 Hz as the ringing signal, which is composed of resistors R ₁ and R ₂ and inverters INV ₁ and INV ₂ and a capacitor C _2. Has been done. Reference numeral 9 is a logic circuit for converting the output of the oscillator 8 based on the control signal S _s output from the CPU 10 as a control unit, which is composed of inverters INV _{3 to} INV ₇ and AND gates AND ₁ and AND ₂ . In other words, the CPU 10 uses the logic circuit 9 to connect the photocouplers PHC _{1 to} PHC.
_{The three} light emitting diodes LED _{1 to} LED ₃ are driven. 11 is DC140V
This is a DC high-voltage generator that generates a DC high voltage of 100V AC and obtains 140V DC by using a power transformer and a rectifier circuit.

The on / off the light emitting diodes LED ₁ ~LED _3, the phototransistor PT ₁ of speech current supply lines L _1, L ₂ photocoupler PHC ₁ ~PHC ₃ connected between the DC high voltage source 11
~ PT ₃ turns on / off. The resistor R ₆ and the capacitor C ₁ and the resistor R ₇ and the capacitor C _{1 form} a time constant circuit. The diode D ₁ blocks the high DC voltage output from the high DC voltage source 11 from entering the speech current supply line 7.

Response detection circuit is photo coupler PHC ₄ and analog switch A
-SW 'and the light emitting diode LED ₄ of the photocoupler PHC ₄ inserted and connected to the call current supply line L ₂ is turned on / off depending on the presence or absence of the call current. Analog switch A-SW 'is CPU1
It is for transmitting the ON / OFF operation of the phototransistor PT ₄ of the photocoupler PHC ₄ to the CPU 10 based on the control signal S _s from 0. That is, analog switch A-
SW 'defines the timing for detecting the on / off of the phototransistor PT ₄ , that is, the presence or absence of a call current. It should be noted that the CPU 10 controls not only the operations required for sending the calling signal and detecting the response, but also all the operations required for the key telephone device.

The operation will be described below with reference to FIGS. 3 and 4. First, the sending of the ringing tone will be described.

When the handset 2 of the telephone set 2 is on-hook, that is, when the handset is set on the main body of the telephone set 2, the hook switch HS is closed to the ring tone generation circuit 4 side as shown in FIG.

In this state, when the main unit 1'detects an incoming call to the telephone 2 from an office line or an extension line, the CP is routed through a route not shown.
An incoming call detection signal is sent to U10. The CPU 10 holds the control signal S _s , which is an output, at a high level before the incoming call detection signal is sent. When the CPU 10 receives the incoming call detection signal, as shown in FIG.
A control signal S _s that is a high level repetition for 2 seconds is output. The control signal S _s is converted by the inverter INV ₇ into a start signal S _p as shown in FIG. 4 (b).

On the other hand, the oscillator 8 constantly generates a 16 Hz rectangular wave.
Since the control signal S _s is at the high level until the incoming call detection signal is received, the activation signal S _p is at the low level and the logic circuit 9
, That is, the outputs of the inverters INV _{4 to} INV ₆ are at high level. Therefore, during this period, photo couplers PHC _{1 to} PHC ₃
Is in the off state, and the high DC voltage output from the high DC voltage source 11 is not supplied to the ringing tone generation circuit 4.

When the activation signal S _p becomes high level after receiving the incoming call detection signal, the output of the inverter INV ₆ becomes low level and the photocoupler PHC ₃ is turned on. On the other hand, the inverter INV ₄ , INV ₅
Since the outputs of the AND gates AND ₁ and AND _{2 which} respectively receive the output of the oscillator 8 and the output of the inverter INV ₇ are input, are synchronized with the low frequency pulse from the oscillator 8 and alternately set to the high level, Repeat low level. Inverter
When INV ₄ is low level (inverter INV ₅ is high level), photocoupler PHC ₁ is turned on (photocoupler PHC ₂ is turned off), and DC high voltage RV output from DC high voltage generation source 11 becomes a resistor. It is supplied to the ring tone generation circuit 4 via R ₆ , the call current supply line L ₁ and the capacitor C ₁ , and the capacitor
Charged to C ₁ . When inverter INV ₄ is at high level (inverter INV ₅ is at low level), photocoupler PHC ₁ is off (photocoupler PHC ₂ is on) and DC high voltage source
The ground level RG of 11 is connected to the ring tone generation circuit 4 via the resistor R ₇ and the capacitor C ₁ , and the capacitor C ₁ is discharged. Therefore, while the activation signal S _p is at a high level for 1 second, a high-voltage AC voltage having a frequency of 16 Hz is applied to the ringing tone generating circuit 4 of the telephone 2, and an AC current of 16 Hz flows to cause the ringing tone generating circuit 4 to receive the ringing tone. To occur. This ring tone is sent until the main device 1'detects the off-hook of the telephone 2, that is, the response.

(Problems to be solved by the invention) By the way, in this key telephone device, in order to determine whether the off-hook of the telephone set 2 is off-hook for making a call or off-hook for answering, a control signal is detected when a response is detected. I am _trying to use S _s . However, when the control signal S _s is used, the response detection timing is restricted. This will be explained below.

When the telephone 2 goes off-hook, the hook switch HS closes to the call current supply line L ₂ side, and the call current supply lines L ₁ and L ₂
A call current is supplied from the call current supply circuit 7. When the call current flows through the call current supply lines L ₁ and L ₂ , the light emitting diode LED ₄ of the photocoupler PHC ₄ turns on, and the phototransistor PT ₄ also turns on. The analog switch A-SW ′ can transmit the ON operation of the phototransistor PT ₄ to the CPU 10 only when the control signal S _s is at the high level. That is, the CPU 10 keeps the high-level control signal S
When the phototransistor PT ₄ is turned on while outputting _s , this is discriminated as off-hook for calling. On the other hand, when the control signal S _s , which is a low level for 1 second and a high level for 2 seconds, is output, the CPU 10 outputs the phototransistor PT ₄ when the control signal S _s is high level.
When is turned on, it is determined to be the response of the telephone set 2. At this time, CP
U10 cannot detect the response of the telephone set 2 for one second when the control signal S _s becomes low level (OFF level time in FIG. 4 (g)).

In addition, if the telephone 2 is off-hook when the control signal S _s is at the low level, the CPU 10 cannot detect this response until the control signal S _s goes to the high level, so that the sending of the calling signal is not stopped. Therefore, when the control signal S _s is off-hook when the signal is low level, the signal from the ring tone generation circuit 4 becomes noise and flows into the handset, which gives the user who hears the handset uncomfortable feeling. .

In view of the above problems, the technical problem of the present invention is to provide a button telephone device that can detect a response of a telephone without being affected by the control signal even if a control signal is used for detecting a response of the telephone. It is to provide a response detection circuit.

(Means for Solving the Problems) The present invention comprises a main unit and a plurality of telephones, and the main unit detects a low-frequency pulse generation circuit for a ringing signal and an incoming call to each telephone to detect a ringing signal. In the button telephone device, which includes a control unit for generating a control signal and a circuit for detecting the response of the telephone by detecting the telephone conversation current flowing in the telephone conversation current supply line by the off-hook of the telephone having the incoming call, the response detection circuit is It is characterized in that it includes a switch that defines a timing for detecting the presence or absence of the telephone current, and that the switch is controlled by an output of a logic circuit that processes the low-frequency pulse and the control signal.

(Operation) With such a circuit configuration, the switch is off-hook of the telephone by both the control signal and the low-frequency pulse while the control signal of the ringing signal that repeats the intermittent operation is transmitted from the control unit. Is specified. As a result, the response detection circuit can detect the response of the telephone during the low level of the low-frequency pulse even when the control signal is interrupted, while the control signal is transmitted from the control unit by repeating the intermittent operation. .

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. In FIG. 1, the same parts as those shown in FIG. 3 are designated by the same reference numerals. The operation of the calling signal transmission circuit 6 is the same as that of FIG.

In this embodiment, as a means for defining the operation of the analog switch A-SW, a NAND gate NAND ₁ which receives the output of the inverter INV _{3 and} the output of the inverter INV ₇ for converting the control signal S _s , that is, the activation signal S _p as input. , And the output CONT of the NAND gate NAND ₁ controls the analog switch A-SW. The output of the inverter INV ₃ is an inverted signal of the low frequency pulse output from the oscillator 8 as shown in FIG. 2 (c), and the output of the inverter INV ₇ is as shown in FIG. 2 (b). , An inverted signal of the control signal S _s output from the CPU 10. The output CONT of the NAND gate NAND ₁ is as shown in FIG. 2 (g). The analog switch A-SW is
The phototransistor PT ₄ in the ON level state of FIG.
Can be transmitted to the CPU 10. When the phototransistor PT ₄ is turned on when the output CONT is in the ON level state of FIG. 2 (g) after sending the control signal S _s which repeats the low level for 1 second and the high level for 2 seconds, the CPU 10 turns off the hook. That is, it is determined that a response has been made, and the control signal S _s is held at a high level. In this way, the response of the telephone 2 is detected, and the control signal S _s from the CPU 10 changes to a high-level continuous signal, whereby the sending of the calling signal is stopped.

As is clear from the above description, even when the control signal S _s is at the low level, the phototransistor PT ₄ remains on once the telephone 2 responds. Therefore, a 16 Hz pulse signal is transmitted to the CPU 10 through the analog switch A-SW. Even when such a signal arrives, the CPU 10 determines that the telephone 2 has responded while sending the control signal S _s which keeps the low level for 1 second and the high level for 2 seconds.

(Effect of the Invention) As described above, according to the present invention, the CPU of the main unit always responds to the telephone response regardless of the level of the control signal after the call signal is transmitted by adding a simple logic circuit. Monitoring is performed, and as soon as the telephone is off-hook, it is determined to be a response, and the operation of stopping the sending of the ringing signal is performed. Therefore, even if there is an off-hook when the control signal is at the low level, the generation of the ring tone is immediately stopped, so that the noise due to the ring tone does not flow into the call current supply line, and the user feels uncomfortable through the handset. Never give.

[Brief description of drawings]

FIG. 1 is a circuit diagram of an embodiment of the present invention, FIG. 2 is a signal waveform diagram of each part of FIG. 1, FIG. 3 is a conventional circuit diagram, and FIG. 4 is a signal waveform diagram of each part of FIG. . In the figure, PHC _{1 to} PHC ₄ are photocouplers, A-SW is an analog switch, and HS is a hook switch.

Claims (1)

[Scope of utility model registration request] 1. A main unit and a plurality of telephones, wherein the main unit detects a low-frequency pulse generation circuit for a ringing signal and a control unit for detecting an incoming call to each telephone and generating a control signal of the ringing signal. And a circuit for detecting the response of the telephone by detecting the call current flowing in the call current supply line by the off-hook of the telephone receiving the call, the response detection circuit detects the presence or absence of the telephone current. A response detecting circuit for a key telephone device, comprising a switch for defining timing, wherein the switch is controlled by an output of a logic circuit for processing the low frequency pulse and the control signal.