JP2529186B2 - Button telephone device with on-hook dial function - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a button telephone device with a so-called on-hook dial function, which enables direct dialing without lifting a handset.

2. Description of the Related Art FIG. 2 shows a schematic configuration diagram of a main part of a conventional button telephone device with an on-hook dial function. The structure of this conventional example will be described below with reference to FIG. In FIG. 2, 1 is a call circuit, 2 is a transformer for calls, and 3
Is a relay for forming a DC loop, and 3'is at its contact. Reference numeral 4 is a transistor for driving the relay 3, 5, 6, 7 are flip-flops, and 8 and 9 are inverters. Further, 10 is a monitor key, 11 is an office line key, 12 is a hook switch, 13 is a current control resistor, 14, 15, 16, 17
Is a pull-up resistor.

Next, the operation of the above conventional example will be described. In FIG. 2, the output Q of the flip-flop 5 is at a low level in the so-called on-hook state with the handset (not shown) left. When the monitor key 10 is pressed to turn it on, the output Q of the flip-flop 5 is inverted and becomes high level and latched. In this state, continue to
When 11 is pressed, the output Q of the flip-flop 6 also becomes high level and is latched, and this is applied to the base of the transistor 4 through the resistor 12 to turn on the transistor 4. When the transistor 4 is turned on, the relay 3 is activated to turn on the contact 3'of the relay 3 to form a direct current loop. At this time, if you hooked up the handset,
Since the hook switch 12 is turned on, the input D of the flip-flop circuit 6 is at a high level, and therefore, it is possible to capture the local line only by pressing the local line key 11 without pressing the monitor key 10.

To release the station line captured in the on-hook state,
This is done by pressing the monitor key 10 again. When the monitor key 10 is pressed again, the output Q of the flip-flop 5 is inverted and becomes low level, and the flip-flop 6 is reset, so that the output Q becomes low level, the transistor 4 is turned off, and the contact of the relay is turned on. 3'is opened.

Further, the opening of the office line from the off-hook state can be performed by hooking down the handset.
When you hook down the handset, the hook switch 12
Is turned off and the output Q of the flip-flop 7 becomes high level, the flip-flop 5 is reset, and at the same time, the output of the inverter 9 also becomes low level, the flip-flop 6 is reset and the same as in the case of on-hook. , The station line is opened. As described above, the function of the on-hook dial is realized.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned conventional example, it is necessary to perform two key operations of pressing both the monitor key and the station line key during on-hook dialing, which is inconvenient in terms of operability. It had the drawback of being bad. In addition, there is a risk that if the user does not dial the line with the line being captured, the line may be left in the state of being line-captured at any time, which is extremely inconvenient.

The present invention solves the above-mentioned conventional drawbacks. On-hook dialing can be performed simply by operating the station line key, and if the station line is captured and left as it is, it is automatically set after a certain time. It is an object of the present invention to provide an excellent key telephone device in which the central office line is opened.

Means for Solving the Problems In order to achieve the above object, the present invention eliminates the monitor key, substitutes the function by the station line key, and acquires the station line and opens the station line only by operating the station line key. In addition to the above configuration, a timer is separately used to automatically open the station line when there is no key input for a certain period of time after the station line is captured.

Therefore, according to the present invention, the operation of capturing and opening the station line becomes extremely easy, and when the station line is captured and left without dialing, the operation is automatically performed after a predetermined period of time. It has the effect of opening the central line.

Embodiment FIG. 1 shows the structure of an embodiment of the present invention. First
In the figure, 1 is a communication circuit, 2 is a transformer for communication, 3 is a relay for forming a DC loop, 3'is its contact point,
4 is a transistor for driving a relay, 5, 6 and 7 are flip-flops, 8 is a NOR gate, 9 is a transistor for resetting a timer, 10 is a local line key, 11 is a numeric keypad, 12 is a hook switch, 13 and 14 are timers. Are capacitors and resistors, 15 and 16 are current limiting resistors, and 17, 18, 19, and 20 are pull-up resistors.

Next, the operation of the above embodiment will be described. In the case of on-hook dialing, the handset remains hooked down and the hook switch 12 is off, so the flip-flop 7 is at a low level in the normal state. In this state, when the station line key 1 is pressed, the output Q of the flip-flop 5 becomes high level, is applied to the transistor 4 through the resistor 15, and the transistor 4 is turned on. Therefore, this causes the relay 3 to operate and its contact 3 '
Closes and the line is captured. And at this time resistance 1 at the same time
4, the timer consisting of the capacitor 13 is started. When there is no key input from the ten-key pad 11, the capacitor 13 is gradually charged through the resistor 14 and its voltage gradually increases. When the voltage exceeds the threshold voltage of the OR gate 8, the flip-flop 5 is reset and its output Q becomes low level, so that the local line is automatically opened at this point. If any one of the ten-key pad 11 is pressed before the capacitor 13 is charged to the threshold voltage, the output Q of the flip-flop 6 becomes high level and is latched in that state. 9 to turn on the transistor 9. Therefore, in this case, the input of the NOR gate becomes low level, the flip-flop 5 is not reset, and the station line remains trapped. Since the output Q of the flip-flop 5 can be reversed by pressing the station line key 10 again when the other party is busy or dialing error while dialing on-hook,
This allows the central line to be opened. In this state, the output Q of the flip-flop 5 is at the low level, so that the flip-flops 6 and 7 are reset.

As described above, according to the above embodiment, the line acquisition and release can be performed only by operating the line key, and when the line acquisition is left as it is without dialing, it is automatically performed. The station line is opened after a certain period of time, which is extremely advantageous. According to the above-described embodiment, these functions and operations can be realized with almost the same number of parts as the conventional button telephone device, and there is an advantage that the cost is hardly increased.

Further, according to the above-described embodiment, it is possible to substitute the station line key instead of turning off the hook switch even during off-hook dialing, which is extremely advantageous in practical use.

EFFECTS OF THE INVENTION The present invention is configured as described above, and has the following effects.

(1) It is easy to use because one key operation is required for on-hook dialing.

(2) If there is no dial key operation after the line has been captured, the line will be automatically opened after a certain period of time preset by the timer, so that the line will not be left for a long time. .

(3) Even if the other party is busy during on-hook dialing or if the dialing is wrong and you want to open the station line, you can easily open the station line by pressing the station line key again. Is very easy.

(4) Even when off-hook dialing, you can turn off the hook switch without turning off the hook switch.

(5) The above functions can be realized easily and at low cost.

[Brief description of drawings]

FIG. 1 is a schematic electrical connection diagram of an embodiment of a button telephone device with an on-hook dial function of the present invention, and FIG. 2 is a schematic electrical connection diagram of a conventional button telephone device with an on-hook dial function. 1 ... call circuit, 2 ... call transformer, 3 ... relay, 3 '... contact, 4 ... relay driving transistor,
5, 6, 7 ... Flip-flop, 8 ... NOR gate,
9 ... Transistor, 10 ... Station key, 11 ... Numeric keypad, 12 ... Hook switch, 13 ... Capacitor, 14-20
……resistance.

Claims (1)

(57) [Claims] 1. A first key input detection circuit for detecting when a station line key is operated to turn on and off a station line acquisition relay, and this key input detection circuit is used for the station line key. When the operation is detected and the relay is turned on, the operation is started, and after a predetermined time elapses, the first key input detection circuit is reset and the timer for turning off the relay and the ten-key are operated. A button telephone device with an on-hook dial function, which is provided with a second key input detection circuit for detecting the time and forcibly preventing the reset of the first key input detection circuit by the timer.