JP2989474B2 - On-hook detection device for cordless telephone - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an on-hook detecting device for a cordless telephone.

[0002]

2. Description of the Related Art FIG. 2 shows a conventional cordless telephone on-hook detection circuit.

In FIG. 2, A is a block showing a base unit of a cordless telephone, and 1 is a charger integrally provided with the base unit A, and a rectifying and smoothing circuit for rectifying and smoothing a commercial AC power supply and converting it into a DC power supply. 3 and charging terminals 4 and 5. One charging terminal 4 is connected to the rectifying and smoothing circuit 3, and the other charging terminal 5 is connected to a constant current circuit 6 and an on-hook detection signal generation circuit / charge detection signal generation circuit 7. Reference numeral 8 denotes control means for controlling the entire master unit A, for example, a microcomputer. 34 is a constant voltage circuit, 9 is a communication path switching circuit of the parent device / child device, a ringer circuit, a keyboard,
A main unit of the master unit A including a handset (microphone and speaker) and the like, which is connected to the general subscriber telephone line unit 10. Reference numeral 11 denotes a wireless line unit including a transmission circuit, a reception circuit, an antenna, and the like. Reference numeral 12 denotes a dry battery for backup at the time of power failure, and reference numeral 13 denotes a diode for preventing backflow.

The constant current circuit 6 includes a transistor 14 having a collector connected to the charging terminal 5,
A resistor 15 connected between the emitter of the transistor 14 and ground, and diodes 16 and 16 connected between the base of the transistor 14 and ground.
And a resistor 17 having one end connected to the base of the transistor 14.

The detection signal generating circuit 7 includes a transistor 18 of a common emitter type, the collector of which is connected to a predetermined terminal 2 of the microcomputer 8, and resistors 19 and 20.

Reference numeral B denotes a block showing a slave unit of the cordless telephone. Reference numerals 21 and 22 denote charging terminals provided on the slave unit B side.
A rechargeable battery 24 is connected between the one charging terminal 21 and the other charging terminal 22 via a backflow preventing diode 23. Between the charging terminals 21 and 22, first and second voltage detecting resistors R1 and R2 are connected in series.
A connection point 25 between the resistors RI and R2 is a control means for controlling the whole slave unit B, for example, a microcomputer.
26 is connected to a predetermined input port 27.

Reference numeral 28 denotes a wireless circuit unit including a transmitting circuit, a receiving circuit, an antenna, and the like, and 29 denotes a device unit including a keyboard, a handset (microphone and speaker), and the like.

In the circuit shown in FIG. 2, the on-hook detection signal generation circuit 7 also serves as a charge detection signal generation circuit for the battery 24. That is, when the slave unit B is placed on the charger,
When the charging terminals 4 and 21, 5 and 22 are in contact with each other and the commercial power supply is energized, the rectifying / smoothing circuit 1, the main unit side charging terminal 4, the child unit side charging terminal 21, the backflow prevention diode 23, the rechargeable battery 24, A charging current flows through the child device side charging terminal 22, the parent device side charging terminal 5, and the constant current circuit 6, and the rechargeable battery 24 is charged. When a current flows through the constant current circuit 6 of the master unit A, a voltage drop occurs. Therefore, when the slave unit B is not mounted on the charger, the voltage of the charging terminal 5 that has been 0 V increases, and the detection circuit 7 The voltage rises to a voltage at which the transistor 18 is turned on. Therefore, the output of the detection signal generation circuit 7 (the transistor 1
8 collector output) goes low. At this time, the constant current circuit 6 has a low impedance to flow a large current for charging the rechargeable battery 24 of the slave unit B.

The microcomputer 8 of the master unit A detects that the slave unit B is mounted on the charger 1 when the output of the detection signal generation circuit 7 becomes low level, and enters an on-hook state. Then, it is detected that the rechargeable battery 24 has been charged, and the telephone line is cut off or the mode is shifted to the standby mode.

On the slave unit B side, the charging current is
3, and flowing through the charging battery 24, the charging terminals 21 and 22
Since a predetermined voltage is generated between the terminals, the voltage is divided by the resistors R1 and R2 constituting the on-hook detection signal generation circuit / charge detection signal generation circuit 33, and the divided output level is read by the microcomputer 26, and the slave unit B It is detected that is placed on the charger. At the same time, the microcomputer 26 detects that the slave unit B has entered the on-hook state and that the rechargeable battery 24 has reached the charged state, and shifts the slave unit B to the standby mode.

[0011]

In the case of the circuit shown in FIG. 2, when a power failure occurs, power is supplied from the backup battery 12 to the main unit 9 of the master unit A via the backflow prevention diode 13. At the same time, a route for supplying power from the backup battery 12 to the constant current circuit 6, the detection signal generation circuit 7, and the microcomputer 8 of the base unit A via the charging terminals 4, 5, 21 and 22; There is a route for supplying power to each side circuit. Accordingly, when the slave unit B is placed on the charger, the rechargeable battery 24 is charged, and on-hook detection is performed on both sides of the master unit A and the slave unit B (the slave unit B is connected to the charger 1). (Whether or not it is placed).

However, in the case of the circuit shown in FIG. 2, there is a problem that a large charging current always flows from the backup battery 12 at the time of power failure, and the battery life is shortened.

[0013]

SUMMARY OF THE INVENTION In view of the above, the present invention provides a DC voltage source obtained by rectifying and smoothing a commercial AC power supply, and a backup battery for a power failure provided with a base unit connected to a general subscriber telephone line. And a slave unit capable of communicating with the master unit through a wireless line unit, and a charging terminal provided integrally with the master unit and having one charging terminal connected to the DC voltage source and a backup battery and the other charging terminal being connected to the master terminal. A cordless telephone comprising a charger connected to an on-hook detection signal generation circuit on the handset side, and a rechargeable battery connected between one charging terminal and the other charging terminal provided on the slave unit, The master unit is provided with a control circuit that sets the impedance of the circuit on the other charging terminal side of the charger to a low impedance when energized and a high impedance during a power failure, between the charging terminals of the slave unit and the charger. The other charging terminal, characterized in that to connect the circuit means constituting the hook detection signal generating circuit of the slave unit side.

Further, the on-hook detection signal generation circuits on the parent device side and the child device side are also used as charge detection signal generation circuits.

[0015]

According to the above configuration, it is possible to reduce the current consumption from the backup battery at the time of power failure, and to perform on-hook detection for both the master unit and the slave unit.

[0016]

An embodiment of the present invention will be described below.

FIG. 1 is a circuit block diagram showing an on-hook detecting device for a cordless telephone according to the present invention.

In FIG. 1, the same parts as those in FIG. 2 are denoted by the same reference numerals as those in FIG.

In the circuit of FIG. 1, a resistor R3 is provided between the other charging terminal 5 of the charger 1 and the ground, and together with the resistors R1 and R2, an on-hook detection signal generation circuit 33 on the side of the slave unit B is constituted. A transistor 30 of a common emitter type is provided between the base of the constant current transistor 14 and the ground, and the base of the transistor 30 is connected to a terminal 32 of the microcomputer 8 via a resistor 31 (a terminal for generating a control output upon detection of a power failure).
Is different from the circuit of FIG. Other configurations are the same as those in FIG.

In the embodiment shown in FIG. 1, during the power failure, the load of the base unit A is increased in order to extend the life of the backup dry battery 12.
And only the microcomputer 8, the main unit 9, and the wireless circuit unit 11 are configured so that almost no charging current flows through the constant current circuit 6, the detection signal generation circuit 7, and the slave unit B of the master unit A. The on-hook detection signal generation circuits 7 and 33 of the master unit A and the slave unit B are configured to detect the on-hook only by applying a voltage.

That is, the transistor 14 of the constant current circuit 6 having a low impedance is cut off at the time of a power failure while the commercial AC power supply is energized, and at the time of the power failure, both the master unit A and the slave unit B can perform an appropriate on-hook detection. The load is connected.

This will be described with reference to the embodiment shown in FIG.

While the commercial AC power supply is energized, the rechargeable battery 24 of the slave unit B is charged through the same route as in the conventional example, and the charge detection of both the master unit A and the slave unit B is performed.

In the event of a power failure, the transistor 30 is turned on and the transistor 14 of the constant current circuit 6 is turned off at the output of the microcomputer 8, thereby setting the other charging terminal 5 side of the charger 1 to high impedance.

Here, if the resistor R3 is not provided, a voltage substantially equal to the voltage of the backup battery 12 appears at the charging terminal 5 as it is, and no potential difference appears between the charging terminals 4 and 5. Therefore, on-hook detection is possible on the master unit A side, but not on the slave unit B side.

Therefore, in the embodiment of FIG. 1, a resistor R3 of an appropriate value is connected between the charging terminal 5 of the charger 1 and the ground,
A potential difference is generated between the charging terminals 4 and 5 of the charger 1 so that the on-hook detection can be performed on the slave unit B side.

However, the impedance of the resistor R3 is set to be larger than the impedance of the constant current circuit 6, and the conditions are as follows.

A. V24 + VD23> IO × (R1 + R
In the case of 2) (at this time, no current flows through the diode 23), in order for the base unit A to perform on-hook detection,

[0029]

(Equation 1)

[0030]

(Equation 2)

B. V24 + VD23 <IO × (R1 + R
In the case of 2) (at this time, the current also flows through the diode 23 but can be ignored), in order for the base unit A to perform on-hook detection,

[0032]

(Equation 3)

[0033]

(Equation 4)

Here, the terminal voltage of the rechargeable battery 24 is V24
(3.6V in the example). The forward voltages of the diodes 13 and 23 are VD13 and VD23, respectively. The current flowing to the on-hook detection circuit side is IO. The voltage of the charging terminal 5 is V5.
The voltage of the backup battery 12 is V12 (7.5 V in the embodiment). The base voltage required for turning on the transistor 18 is 0.6 V (volt) + α (correction value due to temperature change or the like). The voltage level for detecting that the input port 27 of the microcomputer 26 is at the high level is 0.7 × V
24.

Accordingly, the resistance R is set so as to satisfy the above condition.
1, R2 and R3 are set.

Since the current flowing to the detection signal generating circuits 7 and 33 always flows through the resistor R3, the current from the backup battery 12 is reduced by increasing the value of the resistor R3. And the resistance R3
By determining the values of the resistors R1 and R2 in accordance with the values of the above, the on-hook detection can be performed on both the master unit A and the slave unit B.

[0037]

As described above, according to the present invention, the current consumption from the backup battery at the time of power failure is reduced,
On-hook detection can be performed for both slave units.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an on-hook detection device for a cordless telephone according to the present invention.

FIG. 2 is a block diagram showing a conventional on-hook detection device of a cordless telephone.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charger 4, 5 Charging terminal of slave unit 7 On-hook detection signal generation circuit of master unit 8 Control circuit 10 General subscriber telephone line unit 11, 28 Wireless line unit 12 Backup battery for power outage 21, 22 Terminal 24 Rechargeable battery 33 Signal generation circuit for on-hook detection on the slave unit side

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04M 1/00-1/24 H04M 1/58-1/62 H04M 1/66-1/78 H04B 7 / 26

Claims (2)

(57) [Claims] 1. A base unit provided with a DC voltage source obtained by rectifying and smoothing a commercial AC power supply and a backup battery for power failure and connected to a general subscriber telephone line unit, and communicating with the base unit through a wireless line unit. A possible slave unit, provided integrally with the master unit, one charging terminal was connected to the DC voltage source and the backup battery, and the other charging terminal was connected to an on-hook detection signal generation circuit on the master unit side. A cordless telephone comprising a charger and having a rechargeable battery connected between one charging terminal and the other charging terminal provided on the child device, wherein the parent device has another charging terminal of the charger. A control circuit for setting the impedance of the terminal-side circuit to low impedance when energized and high impedance during power failure is provided, and between the charging terminals of the slave unit and the other charging terminal of the charger, the on-hook detection of the slave unit is performed. An on-hook detection device for a cordless telephone, wherein circuit means constituting an output signal generation circuit is connected. 2. The on-hook detection of a cordless telephone according to claim 1, wherein the on-hook detection signal generation circuits on the parent device side and the handset side also serve as a charge detection signal generation circuit. circuit.