JPS5840679Y2 - public telephone - Google Patents

Description

[Detailed explanation of the idea] The present invention relates to public telephones.

For example, in a dial call using a public telephone, a billing signal is sent from the station equipment to the telephone when the called party answers or every time one call time elapses.

A DC polarity reversal signal that reverses the polarity of the line current from the station equipment is used as this billing signal.

Public telephones receive this polarity reversal toll signal and perform operations such as storing coins, but because these operations are performed by reversing the polarity of the line current, conventional telephones have a connection between the central office line and the telephone. The polarity of the connection with the terminal is predetermined, and if the polarity of the connection is reversed, operations such as coin storage will not be performed normally.

The object of the present invention is to correct this drawback and provide a public telephone that can normally perform operations such as storing broken currency regardless of the polarity of the connection between the central office line and the terminal of the telephone.

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

In FIG. 1, Ll and R2 are the first and second terminals of a public telephone connected to the central office line, and the first and second terminals L1 and R2 are
A communication circuit 10 is connected between them.

R31 is a hook switch contact, B is a magnetic bell, C1 is a capacitor for bypassing the AC calling signal from the station equipment when a call is received, R32 is a hook switch contact, D
1 is an impulse contact of the dial, and D5 is a short-circuit contact when dialing.

10 is a communication circuit, which includes a transmitter T, a receiver R1, a guide wire IND, resistors R1, R2, R3, and a capacitor C2°C.
3. Consists of varistor VRI, etc.

Reference numeral 20 denotes a polarity reversal signal receiving circuit, which includes a direction detection circuit 30, a memory circuit 40, and a polarity reversal signal determining circuit 50.

The direction detection circuit 30 includes photocouplers PCI and PC2, resistors R4 to R8, and a varistor VR2.

The cathode of the photocoupler PC1 is connected to the second terminal L2, and the anode of the photocoupler PC2 is connected to the second terminal L2 via a resistor R6.

In addition, the collectors of photocoupler PCI and PC2 are connected to the power supply V.
The emitters are connected to ground through resistors R7 and R8, respectively.

Therefore, when a line current is flowing in the communication circuit 10, with the first terminal L1 having ten polarity and the second terminal L2 having one polarity, only the light emitting diode of the photocoupler PCI emits light, and the light emitting diode of the photocoupler PC2 does not. Since no light is emitted, the emitter terminal of the photocoupler PCI has a high potential H level, and the emitter terminal of the photocoupler PC2 has a low potential L level.

When the direction of the line current is reversed, the emitter terminal of photocoupler PC1 becomes the low potential L level, and photocoupler PC1
The emitter terminal of No. 2 has a high potential H level.

In this way, the direction in which the line current flows is detected by the direction detection circuit 30, and a direction detection signal (H or L) is output from the direction detection circuit 30.

The varistor VR2 is used to absorb overvoltage and prevent excessive reverse voltage from being applied to the photocouplers PCI and PC2.

Resistors R5 and R6 are each connected to a photocoupler PC1.
It is inserted in series with PCI and PC2 to stabilize the current of photocouplers PCI and PC2 and limit excessive current.

Resistor R4 connects to the photocoupler PC when the line current is below a predetermined value.
I, to bypass weak current so that PC2 does not operate, and to prevent minute alternating current signals such as call signals from being temporarily blocked by photocouplers PCI and PC2 and varistor VR2 due to polarity reversal signals etc. It is for the purpose of

Of course, the above bypass effect can also be obtained by connecting a capacitor (not shown) in parallel to the resistor R4.

The storage circuit 40 is for storing the direction detection signal of the direction detection circuit 30 after a predetermined period of time after the DC loop of the communication circuit 10 is formed.

This memory circuit 40 is composed of a delay type flip-flop FF, and its D input terminal is connected to the emitter of a photocoupler PC1, and its C input terminal receives an output from a polarity determination pulse generation circuit 61 in a control circuit 60, which will be described later. A polarity determination pulse is input.

This polarity determination pulse is transmitted to the transmitter/receiver (
After the hook switch contact H82 is closed and a DC loop is formed (see Figure 2 A), after a predetermined time t2 (as shown in Figure 2), the incoming call (after the polarity reversal time t1 of the line current), and falls when the hook switch contact H82 is opened when the handset is turned on.

This flip-flop lower F is reset by inputting a reset signal (2) to the reset input terminal R when the power is turned on.

When the output signal from the emitter of the photocoupler PCI is H, the Q output of the flip-flop FF changes from the L state to H at the rising edge of the polarity determination pulse, as shown in Figure 2 (2), and from then on. This output state is maintained until the handset is turned off, regardless of changes in the input signal to the input terminal.

Further, when the output signal from the emitter of the photocoupler PC1 is L, the Q output is held in the L state until the handset is turned off, regardless of changes in the input signal to the input terminal.

The reason why the current direction of the line current is memorized by the polarity determination pulse when a predetermined time has elapsed after the DC loop is formed in the call circuit 10 is because in the case of an incoming call, the switchboard It takes a certain amount of time to detect this, as shown by the mouth in Figure 2.
In some exchanges, the line is in a polarity reversal state during this time, so this is to prevent the memory circuit 40 from erroneously storing the direction of the line current flow, and the line current is transient immediately after the polarity reversal. This is to prevent the memory circuit 40 from erroneously memorizing the direction in which the line current flows, since the line current vibrates automatically.

The polarity reversal signal determination circuit 50 is for outputting a polarity reversal detection signal while receiving a direction detection signal in the opposite direction to the direction detection signal stored in the storage circuit 40 from the direction detection circuit 30. It is composed of NAND circuits 51, 52 and 53.

A photocoupler PC is connected to the first input terminal of the NAND circuit 51.
The emitter of the photocoupler PC2 is connected to the first input terminal of the NAND circuit 52.

Further, the Q output is input to the second input terminal of the NAND circuit 51 and the second input terminal of the flip-flop NAND circuit 52,
Further, the polarity determination pulse is provided by the NAND circuit 51.

It is configured to input to the third input terminal of No. 52.

Reference numeral 60 denotes a control circuit for controlling toll collection, telephone calls, etc. based on the output of the polarity reversal signal discrimination circuit 50.

61 is the polarity determination pulse generation circuit described above.

Next, the operation of the above circuit will be explained.

When the handset is raised and a coin is inserted, contact H82 of the hook switch closes.

When the first terminal L1 is connected to the office line with + polarity and the second terminal L2 is connected with unipolarity to the office line, the following DC loop is formed in the communication circuit 10 and line current is supplied from the office equipment.

In this way, since the light emitting diode of the photocoupler PCI emits light, the phototransistor becomes conductive and the photocoupler P
The emitter terminal of CI becomes H, and on the other hand, the photocoupler PC
Since the light emitting diode No. 2 is not emitting light, the emitter terminal of the phototransistor becomes L.

Since the flip-flop FF is reset while the input signal of the C input terminal of the flip-flop FF is L,
The output level and Q output are high.

While the input signals at the third input terminals of NAND circuits 51 and 52 are at L, the output signals of NAND circuits 51 and 52 are both at H, so the output signal from NAND circuit 53 is at L.

When the polarity determination pulse rises, the direction in which the line current flows is stored in the flip-flop FF, and the Q output becomes H and the Q output becomes L.

Further, the input signal at the third input terminal of the NAND circuits 51 and 52 becomes H.

The L signal of the Q output is input to the NAND circuit 51, and the NAND
Since the L signal from the emitter terminal of the photocoupler PC2 is input to the D circuit 52, the NAND circuits 51 and 52
Since both output signals are H, the NAND circuit 53
The output signal continues in the L state.

Next, when the polarity reversal billing signal is sent out from the station equipment, the next DC loop is formed and line current is supplied from the station equipment.

In this way, since the light emitting diode of photocoupler PC2 emits light, the phototransistor becomes conductive and the photocoupler P
The emitter terminal of C2 becomes H.

Therefore, the input signal at the first input terminal of the NAND circuit 52 becomes H.

Since the input signals of the second and third input terminals both remain at H, the output signal of the NAND circuit 52 becomes L.

Therefore, the output signal of the NAND circuit 53 becomes H, and a polarity reversal detection signal is output to the control circuit 60.

Upon receiving this polarity change detection signal, the control circuit 60 performs operations such as storing coins.

After the polarity reversal charge signal ends, the first terminal becomes ten polarity and the second terminal becomes ten polarity again.
When the terminal returns to unipolar, the output signal of the NAND circuit 53 becomes L, and the polarity reversal detection signal also ends.

Thereafter, every time a polarity reversal charge signal is sent from the station equipment to the telephone side, a polarity reversal detection signal is sent from the NAND circuit 53 to the control circuit 60.
Operations such as storing coins are performed manually.

Next, a case will be described in which the first terminal Ll and the second terminal L2 are connected with polarities opposite to those in the above case.

First, when a DC loop is formed and a line current flows through the second terminal L2 with ten polarity and the first terminal L1 with one polarity, the emitter terminal of photocoupler PC1 becomes L.

The input signal of the third input terminal of the NAND circuit 51 and 52 is L
During this period, the output signals of the NAND circuits 51 and 52 are both high, so the output signal of the NAND circuit 53 is low.

The polarity determination pulse rises and becomes H, and the NAND circuit 51.
Even if the third human input signal of 52 becomes H, the NAND circuit 51
The output signal from the emitter terminal of the photocoupler PCI to the
(7) Since the Q output is L, the NAND circuit 51.
Since all the output signals of NAND circuit 52 are at H level, the output signal of NAND circuit 53 is at L level.

Next, when a polarity reversal billing signal is sent from the station equipment and a line current flows in the opposite direction, the output signal from the emitter terminal of the photocoupler PC1 changes to H and is input to the first input terminal of the NAND circuit 51.

Since the input signals of the second and third input terminals both remain at H, the output signal of the NAND circuit 51 becomes L.

Therefore, the output signal of the NAND circuit 53 becomes H, and a polarity reversal detection signal is input to the control circuit 60 to perform operations such as storing coins.

After the polarity reversal charging signal ends, the second terminal L2 becomes ten polarity again.
When the first terminal L1 returns to unipolar, the NAND circuit 53
The output signal also becomes L, and the polarity reversal detection signal ends.

Thereafter, a polarity reversal detection signal is outputted from the NAND circuit 53 every time the polarity reversal charge signal is generated, and operations such as coin storage are performed.

In this way, regardless of the polarity of the connection between the first and second terminals, operations such as coin storage can be performed normally upon receiving the polarity reversal billing signal.

When a call is received, an AC calling signal sent from the station equipment passes through the capacitor C1 and operates the magnetic bell B.

When the handset is raised, contact H8I of the hook switch opens to restore the magnetic bell B, and contact H82 of the hook switch opens to form a loop circuit similar to that described above.

After this DC loop is formed during an incoming call, when the exchange detects this, the line current changes polarity as shown in Figure 2, but the polarity determination pulse is delayed for a time longer than this polarity reversal time. Since it is configured to stand up at NAN
The input signals of the third input terminals of the D circuits 51 and 52 are both L, and the output signals of the NAND circuits 51 and 52 are both H.
Therefore, the output signal of the NAND circuit 53 is L.

When the polarity determination pulse rises and becomes H, the first terminal Ll
, N regardless of the polarity of the connection of the second terminal L2.
Either the input signal to the first or second input terminal of the AND circuit 51 is L, and the input signal to the first or second input terminal of the NAND circuit 52 is L, so N
The output signals of AND circuits 51 and 52 are both high.

Therefore, the output signal of the NAND circuit 53 is L.

When a call is received, the polarity reversal charging signal is not sent out from the station equipment, so the output signals of the emitter terminals of the photocouplers PCI and PC2 do not change, so the output signal of the NAND circuit 53 remains at L.

Therefore, when a call is received, the polarity reversal detection signal is not output to the control circuit 60, and operations such as coin storage are not performed.

Note that in the above embodiment, a case has been described in which a photocoupler is used as the direction detection circuit 30, but a relay or other detection means may also be used.

For example, in FIG. 3, relays RLI and RL2 are connected in parallel with diodes DI and D2 connected in series with opposite polarities, and in FIG. are installed in series.

In Fig. 3.4, C4 is a capacitor for bypassing the speech signal, rl1. rl2. rl 3. rl
4 is each relay RLI.

RL 2. RL 3. The contacts R9 and R10 of RL4 are resistors, and if the first terminal L1 is ten polar and the second terminal L2 is unipolar, relays RLI and RL3 operate and contact r1
1, rl3 is closed, and when the polarities of the first and second terminals Ll and L2 are opposite, relay RL2. RL4 operates and contact rl
2. When rl 4 is closed, the direction detection circuit 30 outputs a direction detection signal for detecting the direction in which the line current flows.

Although the embodiments of the present invention have been described above, it goes without saying that various modifications can be made in the configuration of each part without departing from the gist of the present invention.

Since the present invention is configured as described above, the central line and
Regardless of the polarity of the connection with the second terminal, once the polarity reversal charging signal is received, operations such as coin storage can be performed normally, eliminating the conventional problems caused by incorrect connection polarity. be able to.

[Brief explanation of drawings]

Figure 1 is a circuit diagram showing an embodiment of the present invention, and Figure 2 is an operational waveform diagram, where A is the hook switch, mouth is the line current for incoming calls, C is the polarity determination pulse, and 2 is the flip-flop FF. A waveform diagram showing the Q output and FIG. 3.4 are circuit diagrams showing another example of the direction detection circuit. Ll...first terminal, Ll...second terminal, 10...talking circuit, 20...polarity reversal signal receiving circuit, 3o... Opening direction detection circuit, 40...
... Memory circuit, 50 ... Rotating pole signal discrimination circuit, 51,
52.53...NAND circuit, 6o...
- Control circuit, 61...Polarity determination pulse generation circuit.

Claims (1)

[Scope of utility model registration request] a telephone communication circuit, a polarity reversal signal receiving circuit that is connected to the office line via first and second terminals and receives a polarity reversal billing signal sent from the station equipment, and charge collection based on the output of the polarity reversal signal receiving circuit. In a public telephone equipped with a control circuit for controlling a return operation or a call; the polarity reversal signal receiving circuit is connected to the office line in series with the telephone call circuit, and is connected in parallel with each other with opposite polarities to detect direction. first and second unidirectional current detection means for respectively outputting signals; storage means for storing the direction detection signal after a predetermined time after formation of the DC loop of the communication circuit; and the direction stored in the storage means. polarity reversal signal determining means for receiving a direction detection signal in the opposite direction to the detection signal from the first and second unidirectional current detection means and outputting a polarity reversal detection signal; 1. A public telephone set, wherein a polarity reversal detection signal is output to the control circuit when a polarity reversal charge signal is sent from the station equipment, regardless of the polarity of the connection between the terminal and the office line.