JPH0580075U - Dial pulse detection circuit - Google Patents

Abstract

(57) [Abstract] [Purpose] A dial pulse detection circuit for preventing erroneous dial detection in the telephone 10 due to leakage current generated in an open loop (loop break) state (that is, during a dial break) in a digit-corresponding dial pulse signal. Offer of. [Structure] A light emission preventing resistor R is connected in parallel to a light emitting element 14 for detecting a digit-corresponding dial pulse signal as a digit-corresponding optical signal, and the telephone is generated in the digit-corresponding dial pulse signal by the light emission preventing resistor R. The light emission of the light emitting element due to the leakage current is blocked, and the dial pulse signal is accurately detected.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention corresponds to each digit of a multi-digit dialed digit to be transmitted, and by the same number as the digit of each digit, a digit-corresponding dial pulse signal composed of pulses generated in the telephone, in the main device, The present invention relates to a dial pulse detecting circuit provided in the main device for detecting.

[0002]

[Prior Art]

 This type of dial pulse detection circuit is used in a telephone device as shown in FIG. 2 (button telephone device in the example shown). The telephone device of FIG. 2 has a telephone (single telephone in the illustrated example) 10 and a main device 11 connected between the telephone 10 and at least one communication path (not shown).

The telephone 10 has a call circuit 12 and a hook switch HS. The hook switch HS is in the on-hook state in the illustrated state. The call current supply circuit 13 supplies a DC call current to the call circuit 12 when the telephone 10 is in the off-hook state. The call current supply circuit 13 and the call circuit 12 form a loop via the hook switch HS. When the hook switch HS is in the off-hook state, the loop is a closed loop, and when the hook switch HS is in the on-hook state, the loop is open. It becomes a loop.

The loop-detecting light-emitting diode 14 detects the closing of the loop (that is, off-hook of the telephone 10) and outputs an off-hook detection optical signal. The phototransistor 15 converts the off-hook detection optical signal into an off-hook detection electric signal. The light emitting diode 14 and the phototransistor 15 form a photocoupler. In response to the off-hook detection electric signal, the control unit 16 outputs an on / off control signal indicating that the connection is on, and a call path switch (not shown) is provided with a primary winding of the call path and a transformer (not shown). Connect between the wires. Both ends of the secondary winding of the transformer are connected to both ends of the call current supply circuit 13, and as a result, the secondary winding of the transformer is connected to the call circuit 12 via the light emitting diode 14 and the hook switch HS. It is connected. The transformer is for separating the telephone 10 and the communication path in terms of direct current.

The light emitting diode 14 for loop detection corresponds to each digit of a multi-digit dialed digit to be transmitted, and a digit-corresponding dial pulse composed of pulses generated in the telephone is equal in number to each digit. It is also used to detect the signal. That is, the light emitting diode 14 is used as a light emitting element that generates an optical pulse in response to the pulse of the digit-corresponding dial pulse signal and outputs a digit-corresponding optical signal composed of the optical pulse. In this case, the phototransistor 15 functions as a photoelectric conversion element that converts the digit-corresponding optical signal into a digit-corresponding electric signal and gives the digit-corresponding electric signal to the control unit 16 as a digit-corresponding dial pulse detection signal. The control unit 16 receives a dial pulse detection signal corresponding to the digit, which is an intermittent electric signal, and disconnects a relay contact (not shown) of a dial signal transmission circuit (not shown) to connect to the call path. Sends a digit-compatible dial signal.

[0006]

[Problems to be solved by the device]

 Since there is no clear standard for the leakage current at the time of dial break of the telephone set 10, depending on the type of the telephone set 10, at the time of the dial break of the telephone set 10, this leakage current causes the light emitting diode 14 to emit light, resulting in false dial detection. .. A dial break means an open loop (loop break) state in the digit-corresponding dial pulse signal generated by the telephone 10.

An object of the present invention is to provide a dial pulse detection circuit that can accurately detect a dial pulse signal.

[0008]

[Means for Solving the Problems]

 According to the present invention, in correspondence with each digit of a multi-digit dialed number to be transmitted, a digit-corresponding dial pulse signal composed of pulses generated in the telephone is equal to the number of each digit in the main unit. A dial pulse detection circuit provided in the main device for detecting, which generates an optical pulse in response to the pulse of the digit-corresponding dial pulse signal, and generates a digit-corresponding optical signal composed of the optical pulse. A dial pulse detection circuit having a light emitting element for outputting and a photoelectric conversion element for converting the digit-corresponding optical signal into a digit-corresponding electric signal and outputting the digit-corresponding electric signal as a digit-corresponding dial pulse detection signal. , A light emission blocking resistor which is connected in parallel to the light emitting element and which blocks light emission of the light emitting element due to leakage current generated in the telephone corresponding to the digit-corresponding dial pulse signal Dial pulse detection circuit is obtained, characterized in that it comprises.

[0009]

【Example】

 Next, an embodiment of the present invention will be described with reference to the drawings.

Referring to FIG. 1, a telephone device having a dial pulse detection circuit according to an embodiment of the present invention includes the same parts as those of the telephone device of FIG. In this telephone device, a light emission blocking resistor R, which is connected in parallel with a light emitting diode 14 in the main device 11 and blocks the light emission of the light emitting diode 14 due to the leakage current generated by the telephone 10 in the digit corresponding dial pulse signal Have. The light emission blocking resistor R absorbs the leakage current generated by the telephone 10 during the dial break and blocks the light emitting diode 14 from emitting light due to the leakage current.

[0011]

[Effect of the device]

 According to the present invention, the light emission blocking resistor connected in parallel with the light emitting element prevents the telephone from emitting light due to the leakage current generated in the dial pulse signal corresponding to the digit. The effect is that the signal can be detected.

[Brief description of drawings]

FIG. 1 is a block diagram of a telephone device having a path according to an embodiment of the present invention.

FIG. 2 is a block diagram of a telephone device having a conventional dial pulse detection circuit.

[Explanation of symbols]

 10 Telephone 11 Main Unit 12 Call Circuit 13 Call Current Supply Circuit 14 Light Emitting Diode 15 Phototransistor R Resistance

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Hiroshi Sakaino 1-6, 1-chome, Saiwaicho, Chiyoda-ku, Tokyo Nihon Telegraph and Telephone Corporation

Claims (1)

[Scope of utility model registration request] 1. A digit-corresponding dial pulse signal consisting of pulses generated in a telephone set corresponding to each digit of a multi-digit dialed digit to be transmitted is equal to the digit of each digit in the main unit. A dial pulse detection circuit provided in the main device for detecting, which generates an optical pulse in response to the pulse of the digit-corresponding dial pulse signal, and outputs a digit-corresponding optical signal composed of the optical pulse. The light emitting element and the digit-corresponding optical signal are converted into digit-corresponding electric signals,
In the dial pulse detection circuit having a photoelectric conversion element that outputs the digit-corresponding electric signal as a digit-corresponding dial pulse detection signal, the photoelectric conversion element is connected in parallel to the light emitting element,
A dial pulse detection circuit, wherein the telephone has a light emission blocking resistor for blocking light emission of the light emitting element due to a leakage current generated in the digit corresponding dial pulse signal.