JPH0612888B2 - Cordless phone - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone in which a master unit and a slave unit stand are connected by a wireless communication path.

2. Description of the Related Art A conventional cordless telephone will be described below. Second
The figure shows the circuit of the cordless telephone handset,
Reference numeral 1 is a rechargeable battery, and 2a and 2b are switching switches for supplying electric power from the battery 1 to the respective parts, both of which move in an interlocking manner. The switch 2a and the switch 2b have three states, that is, the handset is in a power-off state, a standby state, and a call state.
One of the two states is selected. Reference numeral 3 is a control circuit for exchanging signals with the receiving circuit 5 and the transmitting circuit 6. Reference numeral 4 denotes a speaker that receives a ringing signal sent from the control circuit 3 and generates a ringing tone. The receiving circuit 5 receives the radio signal from the master unit and outputs the signal to the control circuit 3. Further, the transmission circuit 6 sends out a signal input from the control device as a radio signal. Reference numeral 7 denotes a charging terminal that projects to the outside of the slave unit and contacts a terminal on the master unit side when the slave unit is placed on the cradle of the master unit to supply a charging current to the battery 1. 8
Is a diode for preventing backflow from the battery 1 to the charging terminal side.

The operation of the conventional cordless telephone configured as described above will be described below.

First, the case where the switches 2a and 2b are in the "call" state will be described. The voltage of the battery 1 is transferred to the control circuit 3 and the receiving circuit 5 via the contact of the switch 2a, and also to the switch 2
It is supplied to the transmission circuit 6 via the contacts a and 2b. For this reason, the receiving circuit 5 and the transmitting circuit 6 operate to enable a telephone call between the child device and the parent device connected by a wireless communication path.

Next, the case where the switches 2a and 2b are in the "standby" state will be described. In this case, the voltage from the battery 1 is applied only to the control circuit 3 and the receiving circuit 5 via the contact of the switch 2a. If there is an incoming call, an incoming signal is sent from the base unit and received by the receiving circuit 5. And the control circuit 3
Detects that there is a reception and sends a calling signal to the speaker 4. After that, when the switches 2a and 2b are switched to the "passage" state, the base unit and the handset unit are connected to each other via the wireless communication path as described above, and the telephone call becomes possible.

Next, the case where the switches 2a and 2b are in the "off" state will be described. Control circuit 3, receiving circuit 5, transmitting circuit 6
Is disconnected from the battery 1 and is not supplied with electric power, so that all devices in the child device do not operate. When the slave unit is placed on the cradle of the master unit in this state, the charging terminal 7 comes into contact with a charging terminal on the master unit side (not shown), and a charging current is supplied from the master unit side through the diode 8. Battery 1 in the child machine
Is charged.

Problems to be Solved by the Invention However, in the above configuration, when the user places the slave unit on the cradle of the master unit while keeping the switches 2a and 2b in the "off" state, an incoming call from the outside is received. However, there is a problem that the user cannot know the incoming call because the wireless signal from the base unit cannot be received.

The present invention has been made in view of the above problems, and provides a cordless telephone capable of surely notifying a user of an incoming call even when the power of a child device is in an "off" state. The purpose is to do.

Means for Solving the Problems In order to solve the above problems, the present invention provides a device for detecting that the child device is placed on the cradle of the parent device on the child device side, and the child device is on the cradle. The receiver circuit built in the slave unit is operated according to the signal indicating that the slave unit is mounted on the slave unit, and the reception state is maintained even when the slave unit is detached from the master unit according to the incoming signal.

Operation With the above configuration, even if the power switch of the slave unit is "off"
Even if the state is kept as it is, if the handset is placed on the cradle, it becomes a standby state, and the user can surely know the incoming call from the outside. Further, even if a user receives an incoming call in this state and the user lifts the slave unit, the receiving state of the receiving circuit is maintained, so that the standby state can be continued.

Examples Hereinafter, examples of the present invention will be described. FIG. 1 is a main circuit of a slave unit of a cordless telephone in this embodiment, and a power supply battery 1, switches 2a and 2b, a receiving circuit 4 and a transmitting circuit 5 are configured in the same manner as the circuit shown in FIG. It Here, differences from the circuit shown in FIG. 2 will be described. Reference numeral 9 is a transistor whose emitter and collector are respectively connected to the input terminal and output terminal of the switch 2a, and 10 is a resistor inserted between the base and emitter of the transistor 9. 11 is a base having a resistor 12 and a diode 1
It is connected to the charging terminal 7 via 3 and the collector is the resistor 1
4 is a transistor connected to the base of the transistor 9 through 4. Reference numeral 14 is a resistor connected between the base and emitter of the transistor 11. Reference numeral 15 is a resistor, one of which is connected to the base of the transistor 9 and the other of which is connected to the collector of the transistor 11. Reference numeral 16 is a diode, one end of which is connected to the connection point of the resistor 12 and the diode 13 and the other end of which is connected to the control circuit 3 side, and which blocks a current flowing from the charging terminal side to the control circuit side.

The operation of this embodiment will be described below. In this example,
The operation when the slave unit is removed from the cradle is the same as that of the conventional example, and is omitted. Here, the operation when the slave unit is placed on the cradle with the power source switching switches 2a and 2b of the slave unit turned off will be described.

When the slave unit is placed on the cradle, the charging terminal 7 contacts the charging terminal on the master unit side, and the charging current flows from the master unit through the charging input terminal 7 and the diode 8 to charge the battery 1 in the slave unit. It At the same time, the charging voltage on the base unit side is diode 1
3, applied to the base of the transistor 11 via the resistor 12. Then, the collector and emitter of the transistor 11 become conductive, the base of the transistor 9 is grounded through the resistor 15, and a base current flows from the emitter to the base. As a result, the collector-emitter of the transistor 9 becomes conductive, and power is supplied from the battery 1 to the control circuit 3 and the receiving circuit 5.

When an incoming call is received in such a state, an incoming signal is sent from the master unit and received by the receiving circuit 5. Then, the control circuit 3 detects the incoming signal and sends a calling signal to the speaker 4. Further, the control circuit 3 outputs a signal of logical level “H” to the control line 17 in accordance with the incoming signal sent from the receiving circuit 4. This signal is applied to the base of transistor 11 via diode 16 and resistor 12. For this reason,
Even if the charging power source from the parent device is cut off, the transistors 11 and 9 continue to be conductive.

When the user hears the ringing sound, he / she lifts the slave unit, but even if the switches 2a and 2b are still in the "off" state, the control circuit 3 causes the base of the transistor 11 via the control line 17 as described above. Since the "H" signal is applied, the power supply to the control circuit 3 and the receiving circuit 5 is maintained. When the user puts the switches 2a and 2b into the "talking" state, power is also supplied to the transmission circuit 6 through the contacts of the switch 2a. As a result, the base unit and the handset unit are connected to each other via a wireless path, and a call can be made. In addition, a signal indicating that the transmission circuit 6 has operated is input to the control circuit 3 via the control line 18, and in accordance with this signal, the control circuit 3 outputs a signal of logical level “L” via the control line 17. This signal is transmitted to the base of the transistor 11 via the diode 16 and the resistor 12. Therefore, the collector-emitter of the transistor 11 is non-conductive, and the collector-emitter of the transistor 9 is also non-conductive.

When the call ends and the user returns the switches 2a and 2b to the "off" state, the power supply to the transmission circuit 6 is stopped, and the transistor 9 is already in the non-conduction state.
The power supply to the control circuit 3 and the receiving circuit 5 also stops.

When the child device is not used for a long time, the battery 1 will not be unnecessarily discharged if it is kept in the "off" state. If the child machine is placed on the cradle of the parent machine in this state, the operation thereafter is the same as that described above.

The resistors 10 and 14 are connected to the transistors 9 and 1 respectively.
The potential between the base and the emitter of 1 is maintained at the same level to prevent each transistor from inadvertently operating due to noise or the like.

As described above, according to this embodiment, the switches 2a and 2b are
Power is supplied to the control circuit 3 and the receiving circuit 5 of the slave unit when the slave unit is placed on the cradle of the master unit and the battery 1 is charged even when is turned off. Therefore, the slave unit can receive a radio signal from the master unit and can output a ringing tone from the slave unit when an incoming call is received. In addition, the standby state is maintained according to the incoming signal, and the ringing tone does not break even when the handset is lifted. Therefore, the user does not mistakenly think that the incoming call is cut off. As described above, in the cordless telephone according to the present embodiment, the user can surely know the incoming call if the cordless handset is placed on the cradle without considering the states of the power source switching switches 2a and 2b. . Further, if the switches 2a and 2b are turned "off" while the child device is being lifted, the power supply to the circuit is stopped, and unnecessary discharge of the battery can be prevented.

Advantageous Effects of the Invention According to the present invention, the receiving circuit of the child device operates when the child device is placed on the cradle, and the above receiving circuit operates even when the child device is removed from the parent device according to an incoming signal from the parent device. By configuring so that it will continue to operate, even if the slave unit is placed on the cradle with the power turned off, the user can be sure to know the incoming call from outside and use it after receiving the call. Even if a person removes the cordless handset from the cradle with the cordless handset powered off, the ringing tone from the cordless handset does not get interrupted, and there is no concern that the user mistakenly thinks that the call has been disconnected.

[Brief description of drawings]

FIG. 1 is a circuit diagram of essential parts of a cordless telephone according to an embodiment of the present invention, and FIG. 2 is a circuit diagram of essential parts of a cordless telephone of a conventional cordless telephone. 1 ... Battery 2a, 2b ... Switch for switching power supply 3 ... Control circuit, 4 ... Speaker 5 ... Reception circuit, 6 ... Transmission circuit 7 ... Charging terminal 9,12 ... Transistor

Claims (1)

[Claims] 1. A master unit and a slave unit connected by a wireless communication path, wherein the slave unit receives a radio wave from the master unit, and a transmitter that transmits a radio wave to the master unit. A changeover switch for switching between a state in which power is supplied from the battery to the receiver and a state in which power is cut off, and means for notifying the user of an incoming call in accordance with a signal indicating the incoming call received by the receiver, , A switching means for detecting that the child device is placed on the cradle of the parent device and operating the receiver regardless of the state of the changeover switch, and the switching means operates the receiving circuit. When a signal indicating an incoming call sent from the master unit is received in the state where the slave unit is operated, the receiver keeps operating according to the signal so that the receiver continues to operate even when the slave unit is separated from the cradle. Cordless telephone which is characterized in that form.