JP2000278372A - Telephone equipment - Google Patents

Abstract

PROBLEM TO BE SOLVED: To turn on the back light of an LCD with sufficient lightness even in the case of a connection to an exchange for supplying a little station current at the time of trickle charging. SOLUTION: Concerning this telephone equipment, when a user performs off-hook for calling, a hook switch HS is closed, the DC loop of lines L1 and L2 are closed and the station current from the exchange flows to a speech circuit 4 or control circuit 6. A part of an excessive current excepting for a current to be consumed by the speech circuit 4 or control circuit 6 flows through a Zener diode ZD1 and a resistor R6 in an excessive current detecting part 10 to the base of a transistor Q5 and is detected by the transistor Q5 and the transistor Q5 is turned on. Thus, a transistor Q6 in a back light ON control part 11 is turned on and most of excessive currents flow through the turned-on transistor Q6 to an LED 9 for back light and the LED 9 for back light is turned on.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a telephone device, such as a public telephone, which is operated by a station power supply, has an LCD as a display unit, and performs various displays on the LCD.

[0002]

2. Description of the Related Art In this type of public telephone to which no commercial power is supplied, a DC loop of a telephone line is closed by a hook switch when an off-hook is performed, and the telephone is supplied from an exchange through the closed telephone line. The operation is started by the station power supply.

[0003] In such a public telephone, trickle charging is performed for the purpose of quickly starting up a control circuit such as a CPU at the time of off-hook and omitting an extra circuit for activating each circuit at the time of off-hook to reduce cost. Is going. That is, a trickle charge that connects a resistor having a large resistance value between telephone lines and accumulates a weak station current from the exchange side through the resistor as a charge in a large-capacity capacitor for exclusive use while on-hook is performed. At the time of off-hook, together with the station current from the exchange side, the electric charge accumulated in the capacitor is supplied to various circuits to achieve the above object.

Also, when an LCD is used as a display unit in a public telephone, electric charges trickle-charged in a capacitor are used as backlight backlight power for the LCD. When the user goes off-hook and performs a dial operation, dial output is performed on the LCD, and a fixed time L corresponding to the amount of charge accumulated in the capacitor is obtained.
The current from the capacitor to the backlight is limited so that the backlight of the CD is turned on. Therefore, the user can check the dial number operated by the user even in a dark place for the predetermined time.

FIG. 2 is a block diagram showing a main part of a conventional public telephone.
1 shows an example of accumulating the backlight power. In FIG. 2, a rectifier circuit 1 is provided in this public telephone.
And a shunt circuit 3, a shunt circuit 3, a communication circuit 4, and a line L
1, a control power supply unit 5 that inputs a voltage of the Zener diode ZD1 connected to L2 and supplies the voltage to each unit of the public telephone;
A control circuit 6 such as a CPU and a memory;
And an LCD 7 including a backlight LED 9.

Here, a hook switch HS and a relay RL are connected between the line L1 and the diodes D1 and D2 of the rectifier circuit 1.
Are connected in parallel, and the hook switch HS is open at the time of on-hook, so that the station current from the exchange side receives the line L1 → the relay contact RL1, the high-resistance resistor R3, and the diode D1 of the rectifier circuit 1. , Strong-circuit 2
And a weak current is supplied through the path of the shunt circuit 3.

The weak station current flows through the choke coil CH and the diode D6 in the control power supply unit 5 to the electrolytic capacitor C2 having a large capacity, and the capacitor 2C is trickle-charged. Further, the capacitor C3 having a small capacity connected in parallel with the capacitor C2 is also trickle charged via the diode D7.

The sum of the charging voltage of the capacitor C2 and the voltage of the diode D6 and the sum of the charging voltage of the capacitor C3 and the voltage of the diode D7 respectively reach the voltage of the zener diode ZD1 (about 5V or more). Then
Thereafter, the weak current does not accumulate in the capacitors C2 and C3, but flows from the zener diode ZD1 to the line L2 via the diode D4 of the rectifier circuit 1, and in this case, a high-impedance closed loop is formed between the lines L1 and L2. It is formed.

When the user goes off-hook in such a state, the hook switch HS is closed, so that the station current from the exchange side passes through the hook switch HS and the rectifier circuit 1,
Further, the control circuit 6 is supplied to the control circuit 6 via a path (not shown). At this time, the electric charge trickle-charged to the capacitor (not shown) is also supplied to the control circuit 6, and the control circuit 6 is started. When activated, the control circuit 6 drives the relay RL, disconnects the contact RL1 from the resistor R3, and disconnects the rectifier circuit 1
And the contact RL2 in the control power supply unit 5
Is switched to the 5V side. As a result, the hook switch HS
And a control circuit as a 5V power supply from the contact RL2 on the path of the diode D7 of the control power supply unit 5 and the relay contact RL2 via the strong cutoff circuit 2, the communication circuit 4, the zener diode ZD1 and the relay contact RL2 via the rectifier circuit 1. 6 and so on, and the public telephone becomes operable.

Thereafter, when the user operates a dial key (not shown), the control circuit 6 detects this and sends the dial number from the dial circuit (not shown) to the lines L1 and L2, and displays the operated dial number on the LCD.
The data is sent to the driver 8 and displayed on the LCD 7. At the same time, the control circuit 6 turns on the transistor Q6 by turning on the transistor Q5. Then, a current flows from the trickle-charged capacitor C2 to each of the backlight LEDs 9 via the transistor Q6. Thereby, the backlight of the LCD 7 is turned on, and the user can recognize the dial number operated by himself even in a dark place.

The on-resistance of the transistor Q6 for controlling the current value from the capacitor C2 to the backlight LED 9 is determined by the values of the resistors R4 and R5, and depends on the capacitance of the electric charge accumulated in the capacitor C2. In order to continuously turn on the backlight LED 9 for a given period of time, the values of the resistors R4 and R5 are adjusted to determine the on-resistance of the transistor Q6.

[0012]

A conventional public telephone is:
At the time of on-hook, the capacitor is trickle-charged with a local current in advance, and when the hook is off-hook, the backlight of the LCD is turned on based on the charge charged in the capacitor.
However, some exchanges supply a small amount of station current to the public telephone, and if connected to such an exchange, sufficient charge cannot be stored in the capacitor during trickle charging, and therefore the backlight of the LCD will not be sufficient. There was a problem that lighting could not be performed at a high brightness. Also, even in a case where a telephone call is frequently made (that is, when an off-hook / on-hook is frequently repeated), a sufficient charge cannot be stored in the capacitor.
There is also a problem that the backlight cannot be turned on with sufficient brightness. Therefore, an object of the present invention is to turn on the backlight of the LCD with sufficient brightness when connected to an exchange that supplies a small office current at the time of trickle charging, and even when calls are frequently repeated. .

[0013]

In order to solve such a problem, a telephone apparatus according to the present invention performs a predetermined operation based on a station current supplied from a switch via a telephone line and has a backlight. A telephone device provided with an LCD for performing various displays, characterized in that a backlight is turned on using an excess current of a station current supplied from an exchange at the time of off-hook. In this case, there is provided a detecting means for detecting the surplus current among the station currents supplied from the exchange at the time of off-hook, and a backlight lighting control means for transmitting the surplus current detected by the detecting means to the backlight and lighting it. Things. The detecting means detects a current excluding a current required for the predetermined operation from the station current supplied from the exchange as the surplus current. Further, the detecting means comprises a first transistor, a zener diode, a first resistor and a second resistor respectively connected in series to a telephone line, and the backlight lighting control means comprises a first transistor. And a second transistor which is turned on / off in conjunction with the on / off state of the power supply. The station current supplied from the exchange to the telephone line whose DC loop is closed at the time of off-hook is detected by the Zener diode of the detection means and the first transistor. 1st through resistance
When the first transistor is turned on after being detected by the transistor, the second transistor of the backlight lighting control means is turned on, and the station current of the telephone line is supplied to the backlight via the turned on second transistor. It is.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the main configuration of a public telephone to which the present invention is applied. In FIG. 1, this public telephone has a rectifier circuit 1 composed of diodes D1 to D4 connected to telephone lines (hereinafter, lines) L1 and L2, and opens a DC loop of lines L1 and L2 for a fixed time when a call charge is insufficient. Transistor Q for forcibly disconnecting lines L1 and L2
Circuit 2, for example, DP
A shunt circuit 3 including transistors Q3 and Q4 and a resistor R2 for preventing transmission of noise generated at the time of dial transmission to the communication circuit 4 side, and the communication circuit 4 are provided.

The public telephone has capacitors C1 to C3 and choke coil C for supplying station power to each part of the public telephone except for a backlight LED 9, which will be described later.
H, diodes D6, D7 and contact RL2 of relay RL
Control power supply unit 5 comprising:
A control circuit 6 such as a PU and an LCD 7 including an LCD driver 8 and the backlight LED 9 are provided.

Further, the public telephone has a transistor Q5, a zener diode ZD1, resistors R6 and R7 connected in series between the rectifier circuit 1 and the communication circuit 4, respectively.
A surplus current detection unit 10 is provided. The surplus current detection unit 10 is connected to the surplus current detection unit 10 and supplies the surplus current detected by the surplus current detection unit 10 to the backlight LED 9 of the LCD 7. The backlight lighting control unit 11 is provided.
In addition, between the rectifier circuit 1 and the strong cutoff circuit 2 of the above public telephone,
The hook switch HS and the contact point RL1 of the relay RL are connected in parallel.

Next, the operation of the public telephone configured as described above will be described. When on-hook, the hook switch HS is open as shown in FIG. The contact RL1 of the relay RL is also open as shown. Therefore, there is no connection between the rectifier circuit 1 and the strong cutoff circuit 2, and the office power from the exchange is not supplied to each part of the public telephone.

Here, when the user goes off-hook, the hook switch HS is closed, and the rectifier circuit 1 and the hook switch H
S, strong cutoff circuit 2, shunt circuit 3, zener diode Z
D1, resistors R6, R7 and rectifier circuit 1 in line L
A loop of 1 and L2 is formed. Then, the station current from the exchange side is the line L1, the diode D1 of the rectifier circuit 1,
The choke coil CH1 and the diode D6 in the control power supply unit 5 via the path of the hook switch HS, the transistor Q1 of the strong disconnection circuit 2, and the transistor Q3 of the shunt circuit 3.
And stored in the electrolytic capacitor C3 through the diode D7.
It is output from the terminal to the control circuit 6 as a control voltage.

The station current causes the control power supply 5
The control voltage output from the V terminal is supplied to the control circuit 6. When the control voltage is supplied to the control circuit 6 and the potential of the capacitor C2 of the control power supply 5 reaches the reset release voltage of the control circuit 6, the reset of the control circuit 6 is released via a path (not shown). When the reset is released, the control circuit 6 turns on the relay RL, closes the contact RL1, connects the rectifier circuit 1 and the strong disconnection circuit 3 via the contact RL1, and connects the contact RL1 in the control power supply unit 5. Switch RL2 to the 5V terminal side. As a result, the lines L1 and L2 are connected to the relay contact RL regardless of whether the hook switch HS is opened or closed.
1 keeps the loop closed, and charges accumulated in the capacitor C3 of the control power supply unit 5 are transferred to the relay contact RL.
Since the power supply current is output from the 5V terminal via the power supply 2, when the power supply current is supplied to a circuit having a load in which the current flows instantaneously when the power supply is turned on, the power supply current can be quickly supplied and started.

After the control circuit 6 turns on the relay RL to close the contacts RL1 and RL2, it turns off the transistor Q4 of the shunt circuit 3 to turn off the transistor Q3. As a result, the rectifier circuit 1, relay contact RL1 (or hook switch HS), strong disconnection circuit 2, communication circuit 4,
A loop of lines L1 and L2 is formed by the path of the Zener diode ZD1, the resistors R6 and R7 and the rectifier circuit 1. At this time, the station current is supplied to the communication circuit 4 and
Power is supplied to the control circuit 6 through the communication circuit 4 through the path of the choke coil CH, the diode D6, and the 5V terminal of the control power supply unit.

Here, when the station current supplied from the exchange to the public telephone is 50 mA, the current consumed by various circuits such as the communication circuit 4 and the control circuit 6 excluding the backlight LED 9 in the public telephone is 15 mA. Then, an excess current of 35 mA is generated with respect to the station current.

The surplus current flows through the Zener diode ZD1 and the resistor R6 of the surplus current detector 10 to the base of the transistor Q5, where the surplus current is detected by the transistor Q5 and the rectifier circuit 1 via the resistor R7.
Flowing to the side. When the conditions of the current value and the voltage value for turning on the transistor Q5 of the surplus current detection unit 10 are satisfied,
The transistor Q5 turns on, and as a result, the transistor Q6 of the backlight lighting control unit 11 also turns on.

When the transistor Q6 of the backlight lighting controller 11 is turned on, the surplus current still flows through the Zener diode ZD1 and the resistor R6 of the surplus current detector 10 to the base of the transistor Q5.
The current flows to the line L2 via the resistor R7 and the rectifier circuit 1.
However, the surplus current flowing through the above path is small, and most of the surplus current passes through the transistor Q6 of the backlight lighting control unit 11 and the backlight LED 9 in the LCD 7
And the backlight LED 9 is turned on.

Thus, when the user goes off-hook,
LC using the surplus current of the station current supplied from the exchange
The backlight LED 9 of D7 is turned on. afterwards,
When the user dials the other party's number by operating the operation unit (not shown), the control circuit 6 detects this and sequentially sends the dialed number to a dial circuit (not shown) to transmit the lines L1 and L2.
2 as a dial signal, and the operated dial numbers are sequentially transmitted to the LCD driver 8 so that the
Display on D7.

Here, when the dial signal transmitted to the lines L1 and L2 is sent to the exchange, the exchange calls the other party according to the dial signal. When the other party answers this call, a call is started with the user of the public telephone and a call fee is charged. Then, when the call charge runs out during the call, the control circuit 6 turns off the transistor Q2 of the strong cutoff circuit 2 for a certain time, thereby turning off the transistor Q1 for a certain time and forcibly cutting the DC loop of the lines L1 and L2. If the call charge is not insufficient, the call is continued, and thereafter, when the user ends the call and goes on-hook, the hook switch HS is opened. At this time, the control circuit 6 restores the relay RL and opens its contacts RL1 and RL2.
The DC loops 1 and 2 are released, and the supply of office power from the exchange to the public telephone is stopped.

As described above, when the user goes off-hook to make a call, the station current from the exchange is supplied to the call circuit 4 and the control circuit 6 and is consumed by the call circuit 4 and the control circuit 6 and the like. The surplus current other than the detected current is detected by the surplus current detection unit 10 and the detected surplus current is sent from the backlight lighting control unit 11 to the backlight LED 9 of the LCD 7 to turn on the backlight LED 9. . As a result, the backlight LED 9 of the LCD 7 can be illuminated with sufficient brightness regardless of the connection to any exchange, since it is not necessary to light the backlight LED 9 using trickle charging as in the related art. Since the backlight is always on during off-hook, the user can always check the dialed number operated by the user even in a dark place, and therefore, when an incorrect number is operated in a dark place, the user can accurately recognize this. You can confirm and dial again. In the present embodiment, an example of a public telephone has been described. However, the present invention is not limited to this, and the same effects can be obtained when applied to a general telephone.

[0027]

As described above, according to the present invention, the backlight is turned on using the surplus current of the station current supplied from the exchange at the time of off-hook. Since there is no need to turn on the backlight, the backlight can be turned on with sufficient brightness no matter what type of exchange is connected. Further, a detecting means and a backlight lighting control means are provided, wherein the detecting means detects an excess current among the station currents supplied from the exchange at the time of off-hook, and the backlight lighting control means back-ups the excess current detected by the detecting means. Since it is sent to the light and turned on, the backlight is always turned on during off-hook, so the user can always check the dial number operated by himself,
Therefore, when an incorrect number is operated, the user can dial again. In addition, since the current other than the current required for a predetermined operation such as a call or control among the station currents supplied from the exchange is detected as a surplus current, the backlight can be turned on without affecting the call and the control. . The detecting means may include a first transistor, a Zener diode connected in series to the telephone line, and a first transistor.
And the second resistor, and the backlight lighting control means is constituted by a second transistor which is turned on / off in conjunction with turning on / off of the first transistor, so that the DC loop is closed when off-hook. When the first transistor is detected by the first transistor via the zener diode and the first resistor of the detecting means and the first transistor is turned on, the office current supplied to the connected telephone line is supplied to the second switch of the backlight lighting control means. Since the second transistor is turned on and the station current of the telephone line is supplied to the backlight via the turned on second transistor, the backlight can be turned on by detecting the excess current with a simple configuration.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a main part of a public telephone to which the present invention is applied.

FIG. 2 is a block diagram showing a configuration of a conventional public telephone.

[Explanation of symbols]

1 rectifier circuit, 2 strong cutoff circuit, 3 shunt circuit, 4…
Communication circuit, 5: control power supply unit, 6: control circuit, 7: LC
D, 8: LCD driver, 9: LED for backlight,
10: surplus current detection unit, 11: backlight lighting control unit, L1, L2: telephone line, HS: hook switch, R
L1, RL2: relay contact, Q1 to Q6: transistor, D1 to D7: diode, ZD1, ZD2: zener diode, C1 to C3: capacitor, CH: choke coil, R1, R2, R4 to R7: resistor.

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Katsuhiko Hayashi 2-3-2 Shimomeguro, Meguro-ku, Tokyo F-term in Tamura Electric Works, Ltd. (reference) 5K027 BB01 FF22 GG06 MM16 MM17 5K037 AA00 AC03 DA03

Claims (4)

[Claims] 1. A telephone device having an LCD which performs a predetermined operation based on a station current supplied from an exchange via a telephone line, and has a backlight and performs various displays, is supplied from the exchange when off-hook. A telephone device that turns on the backlight by using surplus current of the station current. 2. The system according to claim 1, wherein a detecting means for detecting the surplus current among the station currents supplied from the exchange at the time of off-hook, and the surplus current detected by the detecting means is sent to the backlight and turned on. And a backlight lighting control means for controlling the lighting. 3. The telephone device according to claim 2, wherein the detecting unit detects a current excluding a current required for the predetermined operation from the station current supplied from the exchange as the surplus current. 4. The detecting means according to claim 2, wherein the detecting means comprises a first transistor, a Zener diode connected in series to the telephone line, a first resistor, and a second resistor. And the backlight lighting control means includes a second transistor that turns on and off in conjunction with turning on and off the first transistor, and is supplied to the telephone line with the DC loop closed at the time of the off-hook. When the first transistor is turned on by detecting the station current from the switching device via the Zener diode and the first resistor of the detecting means,
A telephone device, wherein a second transistor of the backlight lighting control means is turned on, and a station current of the telephone line is supplied to the backlight via the turned on second transistor.