JPS61251266A - Sending out circuit for busy tone in public telephone set - Google Patents

Abstract

PURPOSE:To find the cause of busy tone disconnection by making the busy tone to be sent to a user without fail when the compulsory disconnection of a call is performed according to no presence of a coin. CONSTITUTION:When the coil to be contained is not present, a coin containing part (CRC) 1 detects that and so that, according with the state, a control circuit (CNT) 6 makes the transistor Q1 of a loop control circuit (LCT) 3 of, a reversing loop including a call circuit (TKC) 4 is released and the state is held. Therefore, because the function of an exchange is restored to a non-reversing state, the exchange performs always the sending of the busy tone and the busy tone is sent to the receiver R of the TKC4 and it is heard by the user and so, the user can recognize that the call is disconnected due to the shortage of the coin to be thrown.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a public telephone set that is used by being connected to an exchange that maintains a polarity inversion state depending on the response of a called party.

[Conventional technology]

Figure 2 shows a circuit diagram of a conventional example, and the line terminal line Ll to which a telephone line such as a general subscriber line from an exchange is connected is as shown in Figure 3, which shows the line voltage polarity of the telephone line. , when the line terminal is in the hooked state, a voltage is applied from the exchange with the positive terminal at the line terminal, and the public telephone (hereinafter referred to as telephone)
When a coin is inserted after being off-hook, the coin storage section (hereinafter referred to as CRC) 1 detects this and operates contact tpI, so hook switch H8'-diode D,
- Contact 1.1 - Diode DI - Power supply circuit (hereinafter referred to as PS
C) 2-Loop control circuit (hereinafter referred to as LCT) 3-Telephone circuit (hereinafter referred to as TKO) 4-Diode D, -Relay OL'
When the non-inverting loop including l'Kc4 is closed and the dial key (hereinafter referred to as DK) 5 is used to make a dial call, the control circuit (hereinafter referred to as CNT) is activated according to the output of DK5.
)8 controls the LCT3 and turns the transistor QI off and on, and also turns on the transistor Q during this time to send out a dial pulse. In response to the response, the polarity of the line voltage is reversed to create an inverted state, and this state is maintained until on-hook when the call is terminated.

If the line terminal becomes positive due to polarity reversal, it is energized through the route of diode Di - PSC2 - LCT3 - TKC4 - diode D6 - relay KP - contact LpI - diode D, - book switch H8 - relay AN8, and magnetic The latching relay ANS, such as a holding type, operates and holds the diode DI and contacts t and I by the contact ant', thereby closing a polarity reversing loop including TKC4, and the relay KP operates to close the contact. A billing timer (hereinafter referred to as TIM) 7 is started by kp0, from which a periodic billing output is generated, and based on this, coins are repeatedly stored by CRCl until the end of the call.

If there are no coins waiting after being inserted, CRCl will give this information to CNT6 by turning off the transistor Q of LCτ3, opening the polarity reversal loop, restoring the exchanger, and forcing it. The call will be disconnected.

In addition, the constant voltage diode ZD of PSC2 generates a Zener voltage due to the loop current flowing through it, which charges a capacitor (not shown in the diagram) and supplies this terminal voltage as a local power supply V to each necessary part. It is for.

[Problem that the invention seeks to solve]

However, in the above configuration, if the loop is opened,
Since the voltage regulator diode zDl of P2O3 is not energized and the local power supply V is extinguished, the loop opening time by the transistor Qs cannot be made long ibt,b, and the time required for the switching equipment to recover cannot be made long enough. This is a bit long, but it is unspecified whether a dial tone or a busy tone will be sent after the exchange is restored, depending on the type and characteristics of the exchange, the line resistance of the telephone line, etc. ibb has created a problem in which it is impossible for the user to determine for what reason the call was disconnected.

Further, in order to semi-permanently disconnect a call, a latching relay or the like must be separately provided, and a circuit for operating and restoring the relay is required, resulting in a complicated and expensive configuration.

[Means for solving problems]

In order to solve the above-mentioned problem, the present invention is constructed by the following means.

That is, in the above-mentioned telephone, a directional current detection element and a resistor are inserted in series to detect the non-inverting loop current, and the non-inverting loop is closed by the called party's response and opened by on-book. It turns off in response to the absence of coins stored based on the series circuit and the charging output of TIM, opens the polarity reversal loop including 1jlJ TKC, and turns on in response to the detection force of the directional current detection element. Next to T
It is equipped with a switching element that closes a non-inverting loop including KO.

[Effect]

Therefore, when the switching element is turned off and the polarity reversal loop is opened, the exchange recovers in response to this, and if the line terminal returns to the non-inverting state with the positive polarity in response to the restoration, the telephone will be in the non-reversible state. Current passes through the loop, the directional current detection element detects this non-inverting loop current, and this detection force turns on the switching element to close the non-inverting loop including TKO, and the exchanger: Since the busy tone is always transmitted in the non-reversal state immediately after recovery, the user can hear the busy tone.

[Example] Hereinafter, the present invention will be described in detail with reference to figures showing examples.

Figure 1 is a circuit diagram, which is the same as Figure 2, but for the non-inverting loop between the break pole and the main pole of the hook switch H8s, the light emission of the photocoupler PC used as a directional current detection element. A series circuit consisting of a diode and a current limiting resistor h is inserted in series, and CNT6 is given the output direction of the light receiving transistor of the photocoupler PC. According, LCT
After turning off the transistor Q used as the switching element No. 3, if the light-receiving transistor of the photocoupler PC is turned on, this state is reset and the transistor Q is turned off.
, to turn it back on.

Therefore, if you insert an off footer and a coin in the above-mentioned stain filling machine and dial out using DK5, the called party's response will cause the polarity to change.Relay ANS will operate and hold, and relay KP will operate and hold. TIM7 is activated and the coin storage by CRCl is repeated, but during this time, relay AN
8 - Light emitting diode resistor R - Diode D, - contact & 111° non-inverting loop that does not include TKC4 is closed according to the operation of relay AN8 in response to the called party's response, and this non-inverting loop A diode D prevents current from passing through during polarity reversal.

In this state, if there are no coins to be stored, the same <CRCI as described above will detect this, and the CN will respond accordingly.
Since Tfi turns off transistor Q1 of LCT3, the polarity inversion loop including TKC4 is opened and this state is maintained.

Then, in order to restore the exchange and return to the non-inverting state, electricity is applied to the non-inverting loop including the light emitting diode of the photocoupler PC, and this non-inverting loop current causes the light emitting diode to emit light and the current is detected. , the light-receiving transistor is turned on in response to this light emission υ, and due to this detection power, C
NT6 turns on transistor Q1, hook switch H8' - contact ana' - diode D, - PSC
2-LCT3-TKC4-Diode D1-Closes a non-inverting loop including TKC4 of relay OL.

Therefore, in this case, the exchange always sends out a busy tone, and the busy tone is sent to the handset R of TKC4, which is listened to by the user, so the call is disconnected due to insufficient coin insertion. The user will be able to determine the

Also, if on-hook is performed in response to this, the light emitting diode of the photocoupler PC and resistor R1 will be short-circuited as the hook switch H81 is restored, and the relay AN8 will be short-circuited.
- Hook switch H8" - Diode D, - Contact a n
Sufficient current is passed through route a' to restore relay ANS, which restores relay ANS, turns off contact &I, opens the non-inverting loop that does not include fiTKc4, and connects hook switch H8' Contact 1.1 is also restored, the entire loop is opened, and the state returns to the standby state.

Relay RR is for incoming call detection, and when an AC calling signal arrives, the calling signal is passed to capacitor C1 and hook switch H8"t*L? bell B, and when it rings, off-hook is performed. , contact tpI is recovering 1
:) #), diode D, -PSC2-LCT3-
TKC4-Diode D6-Relay KP-Contact 1,
l-Relay RR-Contact rr'-Contact tp2-Low 2-R1
-Hook switch Ha"-: When a calling signal is distributed through the route of I capacitor C1 and the polarity of this signal is set to the line terminal as the positive pole, a latching relay RR similar to the relay ANS operates and holds the contact. rr' prepares the recovery circuit, contact rr' releases the short-circuit to the transmitter TO, and contact rr'' bypasses contacts t and l, allowing a free answer call.

Also, if you go on-hook in response to the end of an answer call,
In this case, since the polarity is in a non-reversing state, the current is applied through the route of book switch Ha' - contact rr' - relay RR - contact Lp - diode D, - PSC2 - LCT3 - TKC4 - diode D, - relay OL, This restores relay RR.

In addition, contact 1.1, together with contact tpI, operates in response to the insertion of a coin and disconnects the circuit of relay RR to prevent the KIJ relay RR from malfunctioning during an outgoing call. an- is for the purpose of short-circuiting the handset T until the called party answers, thereby preventing unauthorized operations and calls.

Note that the relay OL is for detecting loop closure and providing this information to the CNT 6 through contacts not shown in the figure.

Therefore, when a call is disconnected due to a lack of inserted coins, a busy tone is always sent to the receiver R, and the user can easily determine the cause of the disconnection.

In addition, the insertion site of the photocoupler PC's light emitting diode and resistor R7 is such that the relay ANS does not operate in the case of toll-free and incoming call response calls, and has no effect on call operation and call characteristics. In this case, the polarity is inverted during a call, and the diode D prevents current flow, so that there is no effect on the call characteristics.

The insertion locations for the photocoupler PC and resistor R8 can be selected arbitrarily as long as they are equivalent, and a combination of a diode and a relay, a polarized relay, or various semiconductors may be used as the directional current detection element. Various modifications are possible, such as using a relay or a thyristor as the switching element, and also applying it to a telephone using a commercial power source.

〔Effect of the invention〕

As is clear from the above explanation, according to the present invention, with a simple configuration, when a call is forcibly disconnected in response to the absence of coins, a busy tone is always sent to the user, thereby Since the cause of the disconnection is clearly determined, a remarkable effect can be obtained in various public telephones connected to exchanges that maintain the polarity inversion state after the called party answers.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram of a conventional example, and FIG. 3 is a diagram showing line voltage polarity of a telephone line. 1...CRC (coin storage section), 3...L, C
T (loop control circuit), 4"" TKO (talking circuit), 6
#...-CNT (control circuit), T...TIM (charging timer), L input,...fist/line terminal, AN8. R
R%KP, OL...Relay, Is'~H83・
...Hook switch, D. ~D,...Diode, R,, R1...Resistor, PC...Photocoupler (directional current detection element), Ql...Transistor (switching element), R11@@Naki telephone receiver.

Claims (1)

[Claims] connected to an exchange that maintains a polarity inversion state depending on the called party's response, starts a billing timer upon detecting the called party's response, and stores coins based on the periodic billing output of the billing timer; In a public telephone set that performs and a series circuit, which is turned off in response to the absence of coins to be stored based on the billing output, and opens a polarity reversing loop including a telephone call circuit, and is turned on in response to the detection force of the directional current detection element, and is turned on in response to the telephone call circuit. A busy tone transmitting circuit for a public telephone, comprising: a switching element that closes a non-inverting loop including: