JP3013434B2 - Cordless telephone - Google Patents

Abstract

PURPOSE:To connect a slave set and a master set in a short time by devising the telephone set system such that a master set designates a slave set among plural slave sets and sends an incoming call reception request sequentially to them at the arrival of an incoming call and only the designated slave set returns a command signal being the incoming call acknowledge. CONSTITUTION:When a call comes from an external line, a detection circuit 264 of a base unit 2 detects a ring tone signal and the processing of a microcomputer 240 is started. Then a transmission circuit 210 starts the transmission of an FM signal Sd of an outgoing control channel by a control signal TCTL and sends a signal CMND to handsets 1A-1C for each prescribed time sequentially as soon as the command signal CMND being an incoming call reception request is generated. Upon the receipt of the signal CMND, the handsets 1A-1C return an incoming acknowledge. Then the unit 2 sends an identification code and a signal designating a control channel. When own identification code of the handsets 1A-1C is coincident, the coincident handset selects a speech channel. Thus, collision of radio waves is avoided and the connection is implemented in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION The description will be made in the following order.

A Industrial Fields B Overview of the Invention C Prior Art D Problems to be Solved by the Invention E Means for Solving the Problems (FIG. 1) F Function G Examples (FIGS. 1 to 6) H BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cordless telephone, particularly to a cordless telephone that can use a plurality of slave units.

B. Summary of the Invention The present invention relates to a cordless telephone which is capable of using a plurality of slaves, and when receiving a call, specifies a slave to the plurality of slaves and sequentially transmits a command signal for an incoming call request. Only the designated slave unit returns a command signal of an incoming call response, so that the slave unit and the master unit are connected in a short time.

C. Prior Art There are two types of cordless telephones in Japan: a weak type and a low power type. Both types of base units and handset units are configured as transceivers.

Then, taking a low power type cordless telephone as an example, the master unit and the slave unit perform only reception on the control channel during standby.

For example, when there is an incoming call from an outside line, transmission of the master unit is permitted, and a command signal (telegram) of an incoming call request is transmitted from the master unit to the slave unit through the control channel, and the slave unit transmits the command signal to the slave unit. When receiving, the transmission of the slave unit is also allowed,
A command signal of an incoming call response is returned from the child device to the parent device.
Thereafter, a predetermined protocol is executed to open a communication channel between the master unit and the slave unit, and the master unit and the slave unit are connected through the communication channel.

However, in such a cordless telephone, 2
If more than one slave unit can be handled, the following problem occurs.

That is, at the time of an incoming call, when the master unit transmits a command signal of an incoming call request, a command signal of an incoming call response is returned from a plurality of slave units all at once. Then, these command signals cause interference when viewed from the base unit, so that the base unit cannot receive those command signals correctly, and cannot open a communication channel with any slave unit, As a result, the incoming call cannot be received.

In order to avoid such a problem, the master unit selects any one of the plurality of slave units as a representative, and upon receiving a call,
A system has been considered in which a command signal for an incoming call request is transmitted to the representative slave unit.

However, in the case of this system, when the representative handset is moving out of the service area, when the battery is down, when it cannot respond such as when it is out of order, etc. This is determined in some way, another slave unit is selected again as the representative slave unit, and a command signal for an incoming call request is sent to this new slave unit again, so it takes time to open the call channel. Will take.

D Problems to be Solved by the Invention As described above, if a plurality of slave units are simply prepared, a plurality of slave units respond to the incoming call at the same time at the time of an incoming call. May not be connected to the device.

Also, if a representative handset is specified and a command signal for an incoming call request is sent only to that representative handset, when that representative handset cannot respond, it takes time for another handset to respond instead. Would.

The present invention seeks to eliminate these problems.

E Means for Solving the Problems For this reason, in the present invention, when the reference numerals of the respective parts correspond to the embodiments described later, the space between the base unit 2 connected to the line 3 and this base unit during a call is established. In a cordless telephone having a handset 1 connected through a call channel, at the time of receiving a call, the base unit 2 designates each handset in order to a plurality of handset 1A to 1C and issues a command signal of a call request. The designated slave unit transmits the incoming call response command signal to the master while the master unit 2 designates the next slave unit and transmits the incoming call request command signal. The base unit 2 monitors the reception of the command signal of the call response from the slave units 1A to 1C in a time division manner with respect to the transmission of the command signal of the call request, and receives the call by the reception monitor. A connection request is made to the slave unit that has received the request command signal. It is obtained by way.

F operation Even if there are a plurality of slave units, only the slave unit designated by the master unit returns the command signal of the incoming call response, so that collision of radio waves is prevented and the slave unit and the master unit can be connected in a short time. A call channel is opened in between.

G Example In the example shown in FIG. 1, three handsets (slaves) can be used. 1A to 1C are the first to third handsets, 2 is a base unit (master), 3 is Indicates a telephone line (external line). In this case, these handsets 1A ~
Since 1C has the same configuration, when it is not necessary to distinguish between them, the handset 1 is represented.

In the handset 1, reference numeral 110 denotes a transmission circuit, and reference numeral 120 denotes a reception circuit. The transmission circuit 110 converts an audio signal St and a command signal CMND (details will be described later) into an upstream channel FM signal Su and transmits the signal. And the receiving circuit
120 receives the downlink channel FM signal Sd and outputs the audio signal S
r and the command signal CMND are demodulated. Also,
In the receiving circuit 120, for example, by detecting limiter noise generated in the intermediate frequency amplifier, a detection signal SQLC indicating presence / absence of the downlink channel FM signal Sd is also extracted.

Further, in the handset 1, 131 is a dial key, 132 is a talk key, and the talk key 132 is a non-lock type push switch. Each time the key 132 is pressed, the handset 1 switches between the standby mode and the talk mode. To switch alternately. In the standby mode, the handset 1 waits for an outgoing call, monitors a downlink control channel and waits for an incoming call request from the base unit 2, and in the talk mode, the handset 1 Continuous reception and transmission are performed between.

Reference numerals 133 to 137 denote auxiliary keys such as a hold key constituted by a non-locking type push switch; 139, a linger speaker; and 140, a system control microcomputer.

Then, in the microcomputer 140, the command signal CMND transmitted by the transmission circuit 110 is formed, and the command signal CMND and the detection signal SQLC extracted from the reception circuit 120 are determined. Further, in the microcomputer 140, control signals TCTL and RCTL for permitting / prohibiting transmission / reception of the transmission circuit 110 and the reception circuit 120 and specifying a channel are formed. The microcomputer 140 is also provided with, for example, a routine 500 shown in FIG.

Further, 141 is a ROM, 142 is a 2-bit dip switch, for example, and the ROM 141 stores a 25-bit system identification code SYID for distinguishing this cordless telephone from other cordless telephones. The dip switch 142 outputs an identification code HSID for identifying the handsets 1A to 1C.

On the other hand, the base unit 2 has a transmission circuit 210 and a reception circuit 220 similar to the transmission circuit 110 and the reception circuit 120 in the handset 1, and in a standby mode, stands by for an incoming call from the telephone line 3, Receiver circuit
The reception monitor 220 monitors the uplink control channel and waits for a call request from the handset 1, and performs continuous reception and transmission with the handset 1 in the talk mode.

Further, in the base unit 2, reference numeral 240 denotes a microcomputer for system control. The microcomputer 240 performs the same processing as the microcomputer 140 in the handset 1, and also manages the entire operation of the cordless telephone. And in the microcomputer 240,
For example, a routine 600 shown in FIG. 6 is also provided.

241 is a ROM, which corresponds to the ROM 141,
The system identification code SYID is written.

Further, 261 is a 4-wire / 2-wire conversion circuit, 262 is a switch circuit corresponding to a hook switch of a general telephone, 263 is a dial tone signal (DTMF signal) forming circuit at the time of calling, 264
Is a circuit for detecting a ring tone signal when a call is received.

FIG. 2 shows an example of a signal format of the command signal CMND. The signal CMND has a 24-bit bit synchronization signal BSYN at the beginning, and then a 16-bit frame synchronization signal.
Has FSYN.

Further, the command signal CMND has a 25-bit system identification code SYID, a 12-bit error correction code ECC for the code SYID, and a 3-bit dummy bit DBIT in order following the signal FSYN. DB
Following the IT, there is a 5-byte control code CTRL.

In this case, the control code CTRL is the first byte CTL1
Are codes indicating the control contents of the handset 1 and the base unit 2, and the second to fifth bytes CTL2 to CTL5
Are parameters or data related to the first byte CTL1.

For example, when the base unit 2 notifies the handset 1 of the channel number of the call channel, CTL1: a code indicating that the call channel is notified CTL2: identification code HSID of the partner handset 1 CTL3: call channel Channel numbers CTL4, CTL5: Dummy.

And handset 1 or base unit 2
However, when the command signal CMND is received, the microcomputer 140 or 240 stores the identification code SYID (and HSID) included in the signal CMND in its own memory 141 or 2.
It is checked whether or not it matches the identification code SYID (and HSID) stored in 41. Only when it matches, the command signal CMND is validated, and when it does not match, it is ignored.

The time length τ of the command signal CMND is, for example, 80
m seconds.

[During Standby] In the standby mode, in the handset 1, the receiving channel of the receiving circuit 120 is set as the control channel by the control signal RCTL from the microcomputer 140, and the signal SQLC
The control channel is monitored by checking.

When the signal Sd of the downlink control channel is received, the identification code SYID included in the command signal CMND,
The HSID is checked in the microcomputer 140, and if not, the standby mode is continued.

The base unit 2 is also in the standby mode by the same operation.

[At Incoming Call] When there is an incoming call from an outside line, for example, the connection sequence shown in FIG. 3 and FIG. 4 is executed by the routines 500 and 600 shown in FIG. 5 and FIG. . In FIG. 4, solid lines in the vertical direction indicate channels used by the handset 1 and the base unit 2, C is a control channel, and V is a communication channel. Also, the fourth
In the figure, the numbers in the 500s and 600s are the routine 50
Indicates the step numbers at 0 and 600. In addition, the fourth
The figure shows a case where all the handsets 1A to 1C can receive a call normally.

When the handset 1 and the base unit 2 are in the standby mode and there is an incoming call from an outside line, the ring tone signal is detected by the detection circuit 264, and the processing of the microcomputer 240 is performed based on the detection output.
In step 602, it is checked whether or not the control channel is used by checking the signal SQLC. When the control channel is used, this step 602 is repeated. , The process proceeds from step 602 to step 611.

Then, in this step 611, the transmission of the transmission circuit 210 is permitted by the control signal TCTL. For example, as shown in FIG. 3A, the transmission circuit 210 starts transmission of the FM signal Sd on the downlink control channel from time t1. . Then, in step 612, an incoming call timer by software is started.

Subsequently, in step 613, during a period 2τ (for example, τ = 80 msec) from the time point t1 to the time point t2, a command signal CMND for an incoming call request is formed, and at the same time, the signal CMND is supplied to the transmission circuit 210 and downloaded. Is converted to the FM signal Sd of the control channel of the above, and this signal Sd is transmitted from the antenna 200 to the handset 1.

In this case, during the period t1 to t2, the command signal CMND is repeatedly formed and transmitted twice, and the command signal CMND is a signal of an incoming call request designating the first handset 1A.

Then, when this transmission is completed, the process proceeds to step 613.
In step 614, the command signal CMND for the incoming call request is formed during the period 2τ from the time point t2 to the time point t3, and at the same time, it is converted into the FM signal Sd of the downstream control channel and the handset 1 Sent to

In this case, during the period t2 to t3, the command signal CMND is repeatedly formed and transmitted twice, and the command signal CMND is used as a call request signal designating the second handset 1B.

Then, when this transmission ends, the process proceeds to step 615
In this step 615, from time t3 to time t4
During the period 2τ, the command signal CMND for the incoming call request is formed, and at the same time, the FM signal Sd of the downlink control channel
And transmitted to the handset 1.

In this case, the command signal CMND becomes 2 during the period t3 to the time t4.
This command signal CMND is a signal of an incoming call request designating the third handset 1C.

When the transmission in step 615 is completed, the process proceeds to step 616. In this step 616, it is checked whether or not the call response command signal CMND from the handsets 1A to 1C has been received (this call response command signal CMND).
If it is not received, the process proceeds from step 616 to step 617. In this step 617, it is checked whether or not the command signal CMND of the call response has been received from all the handsets 1A to 1C. If not, the process proceeds to step
From 617, proceed to step 618. And this step 618
It is checked whether the incoming timer has passed a time limit, for example, 3.5 seconds. If the time has not elapsed, the process returns from step 618 to step 613.If the time has elapsed, the process returns from step 618 to step 621. Proceed to.

Therefore, when there is an incoming call, all handsets 1A
~ 1C until receiving the call response command signal CMND
Or, until 3.5 seconds elapse from the incoming call, step 613-
Step 618 is repeated, and the call request command signal CMND is repeatedly transmitted to the handsets 1A to 1C.

When the base unit 2 starts the incoming call processing as described above, the handset 1 can receive the FM signal Sd on the control channel downstream from the time point t1.

That is, in the handset 1, the antenna 100
When the FM signal Sd from the base unit 2 is received, the microcomputer 140 is notified of this by a signal SQLC.

Then, the process of the microcomputer 140 starts from step 501 of the routine 500, and in the next step 502, the identification code S of the command signal CMND output from the receiving circuit 120.
It checks if the YID matches yours,
If they match, the process proceeds from step 502 to step 503
In this step 503, the command signal CMND
Is checked whether it is a message for a call request. Then, when the command signal CMND is an incoming call request message, the process proceeds from step 503 to step 504. In this step 504, the control code CTR
It is checked whether or not the handset identification code HSID indicated by L matches its own, and if so, the process proceeds from step 504 to step 511.

Accordingly, in the handset 1, when the command signal CMND of the incoming call request for itself is received on the downlink control channel, the processing proceeds to step 511.

In step 502 or 504, the identification code SY
If the ID or HSID does not match, the process
From 502 or 504, proceed to step 509 to execute this routine 5
End 00. If the received command signal CMND indicates a process other than the incoming call request in step 503, the process proceeds from step 503 to step 508, and the corresponding process is executed in step 508.

Then, when the processing of the microcomputer 140 proceeds to step 511,
The transmission circuit 110 is permitted to transmit the FM signal Su on the uplink control channel by the control signal TCTL.

That is, in the handset 1A, as shown in FIG. 3B, transmission of the FM signal Su is permitted from time t2, and in the handset 1B, as shown in FIG.
, The transmission of the FM signal Su is permitted, and in the handset 1C, the transmission of the FM signal Su is permitted from time t4. That is, the handset 1A-1C receives a command signal
CMND is transmitted twice in a period of 2τ, and is triggered by a command signal CMND in the latter half thereof, and the transmission of the FM signal Su is permitted at the end point.

Then, when the transmission is permitted, the process proceeds to step 512, in which a wait time of, for example, 40 to 60 ms is performed, and then, in step 513, a command signal CMND of an incoming call response is formed. With this signal CM
ND is supplied to the transmission circuit 120 and the F
Converted to M signal Su, antenna 100 from base unit 2
Sent to

Subsequently, in step 514, after waiting for a time of, for example, 40 ms, in step 515, transmission of the FM signal Su is prohibited.

Therefore, from handsets 1A to 1C, FIG.
The command signal CM of the call response at the timing shown in FIG.
The ND FM signal Su will be transmitted. At this time, almost the center of the FM signal Su is modulated by the command signal CMND, but before and after the transmission period of steps 512 and 514, there is no modulation.

Then, in step 516, it is checked whether a connection execution command signal CMND described later has been received. If not, the process returns to step 502.

Therefore, when there is an incoming call from an outside line, the base unit 2 repeatedly transmits the incoming request command signal CMND to each of the handsets 1A to 1C as shown in FIG. 3A in steps 613 to 618. In steps 501 to 517, the handsets 1A to 1C return the incoming response command signal CMND for each incoming request command signal CMND to themselves, as shown in FIGS. 3B to 3D.

In such a state, the base unit 2 monitors the reception of the incoming response command signal CMND in a time division manner in steps 613 to 615.

That is, as shown in FIG. 3, the handset 1A returns the call response command signal CMND during the period in which the call request command signal CMND is transmitted to the handset 1B (for example, period t2 to t3). Therefore, the command signal CMND is monitored for reception in step 614, and the handset 1C
Since the handset 1B returns an incoming response command signal CMND during a period during which the command signal CMND of the incoming call request is transmitted (for example, period t3 to t4), the command signal CMND
Is monitored for reception in step 615 and handset 1
During the period in which the command signal CMND for the incoming call request is transmitted to A (for example, period t4 to t5), the handset 1C returns the command signal CMND for the incoming call response.
CMND is monitored for reception in step 613.

Then, the result of the reception monitoring of the command signal CMND of the incoming call response in these steps 613 to 615 is checked in step 616 as described above, and the handsets 1A to 1A are checked.
When the command signal CMND of the incoming call response from C is not received, the process proceeds from step 616 to step 617,
If received, the process proceeds from step 616 to step 619
In this step 619, the identification codes HSID of the handsets 1A to 1C are
Registered with AM (not shown), and then the process proceeds to step 61
Go to 7.

Also, in step 617, as described above, in steps 613 to 615, it is checked whether or not the command signal CMND of the incoming call response has been received from all the handsets 1A to 1C. The process proceeds from step 617 to step 618, and if received, the process proceeds from step 617 to step 621.

Therefore, when there is an incoming call from an outside line, the base unit 2 repeatedly transmits the incoming request command signal CMND to each of the handsets 1A to 1C as shown in FIG. 3A in steps 613 to 618. In steps 501 to 517, the handsets 1A to 1C return the incoming response command signal CMND for each incoming request command signal CMND to themselves, as shown in FIGS. At this time, the base unit 2 checks the command signal CMND of the incoming call response from the handsets 1A to 1C.

Then, the command signal CMND of the incoming call response is returned from all the handsets 1A to 1C (step 61).
7) When 3.5 seconds have elapsed after the call is received (step 618), the process proceeds to step 621.

Then, in step 621, a connection timer by software is started, and then, in step 622, a command signal CMND for executing connection is transmitted through a downlink control channel. In this case, this command signal CM
The ND has the first identification code HSID among the identification codes HSID of the handsets 1A to 1C registered in the RAM of the microcomputer 240 in step 619, as the control code CTRL,
It also has data for specifying a call channel.

Therefore, this command signal CMND is
Thus, among the identification codes HSID of the handsets 1A to 1C registered in the RAM of the microcomputer 240, this is issued to the handset having the first identification code HSID. FIG. 4 shows a case where the command is issued to the handset 1A.

Then, in step 623, the connection timer
It is checked whether 0.5 second has elapsed, and if not, the process returns from step 623 to step 622. Therefore, in steps 621 to 623, the connection request command signal CMND is repeatedly issued to the handset having the first identification code HSID for 0.5 seconds.

On the other hand, in the handset 1, when a command signal CMND for executing connection is transmitted in step 622, this is detected in step 516, and the process proceeds to step 516.
From step 521.

Then, in step 521, the identification code HSID of the handset included in the command signal CMND in step 622
Is checked to see if it matches its own, and if it does (in FIG. 4, it matches at handset 1A), the process proceeds from step 521 to step 522, where the transmission circuit 110 and The receiving circuit 120 is switched by the signals TCTL and RCTL to the communication channel designated in step 622. Next, in step 523, the command signal CM indicating the completion of the channel switching is output.
ND is formed, and the command signal signal CMND is
The signal is transmitted to the base unit 2 through the uplink communication channel switched in 522, and thereafter, the processing proceeds to step 531.
Proceed to.

In step 521, if the identification code HSID of the handset included in the command signal CMND in step 622 does not match its own (in FIG. 4, it does not match in the handsets 1B and 1C), the process proceeds from step 521. Proceeding to step 524, in this step 524, the transmitting circuit 110 and the receiving circuit 120 are switched to the communication channel specified in step 622 in the same manner as in step 522, and then the process proceeds to step 531.

In the base unit 2, steps 621 to 6
23, the connection request command signal CMND is repeatedly issued to the handset of the first identification code HSID for 0.5 seconds, and thereafter, the process proceeds from step 623 to step 631, where the transmitting circuit 21
0 and the receiving circuit 220 perform step 62 by the signals TCTL and RCTL.
In 2 the call channel is switched to the one instructed to the handset 1. The timing of this switching coincides with the switching of the handset 1 to the communication channel, as shown in FIG.

Then, the process proceeds to step 632 following step 631, in which the channel connection completion command signal CMND transmitted by the handset (the handset 1A in FIG. 4) transmitted in step 523 is received. Then, in step 633, the ringer's command signal CMND is transmitted to the handset 1 through the downlink communication channel switched in step 631.

Then, in the handset 1, the command signal CMND is received in step 531. Based on the command signal CMND, the microcomputer 140 controls the oscillation circuit 138 to form a ringer signal.
Supplied to 9. Therefore, in all the valid handsets 1, a bell sound is emitted from the speaker 139 to notify the incoming call.

Thereafter, when the talk key 132 is pressed in any of the valid handsets 1, this is notified to the base unit 2 by the command signal CMND, and the communication channel between the handset and the base unit 2 is determined and The oscillation circuit 138 is controlled to turn off the ringer. The remaining handsets are returned to the standby mode.

Therefore, the line 3 is connected to the responding one of the handsets 1 through the base unit 2 and the communication channel.

[Call] When the line 3 is connected to the handset 1 through the base unit 2 and the call channel, the voice signal Sr from the other party is output from the line 3 → the switch circuit 262 → the conversion circuit 261.
Is supplied to the transmission circuit 210 through the signal line of FIG. Therefore, the signal Sr is converted into the FM signal Sd of the downlink communication channel, and the signal Sd is transmitted from the antenna 200.

Then, the signal Sd is received by the connected handset 1, an audio signal Sr is extracted from the receiving circuit 120, and the signal Sr is supplied to the receiver 121.

Further, the audio signal St from the transmitter 111 is supplied to the transmission circuit 110 and is converted into an FM signal Su of the uplink communication channel,
The signal Su is transmitted from the antenna 100 to the base unit 2.

Then, the signal Su is received by the base unit 2 and a signal St is extracted from the receiving circuit 220.
Is supplied to the line 3 through the conversion circuit 261 and the switch circuit 262, and is sent to the other party's telephone.

Therefore, a call can be made with the other party using the handset 1.

[At the end of call] When the talk is finished and the talk key of the handset 1 is pressed, the control code CTRL indicates a command signal CMND indicating the end of the call.
Is formed, the signal CMND is transmitted to the base unit 2, and a call termination process such as prohibiting the transmission of the transmission circuit 120 is performed, and the handset 1 enters the standby mode.

Also, in the base unit 2, the handset 1
, The transmission of the transmission circuit 210 is prohibited, and the switch circuit 262 is closed, for example, in an on-hook state. Thereafter, the standby mode is entered.

[At the time of calling] When the talk key 132 of the handset 1 is pressed in the standby mode, the transmission of the transmitting circuit 110 is permitted, and the control code CTRL indicates the calling request and the command signal CMND indicating the identification code HSID. Is formed, and this signal CMND is supplied to the transmission circuit 110 and converted into an FM signal Su of the uplink control channel, and this signal Su is transmitted to the base unit 2.

Then, when the command signal CMND is received in the base unit 2, it is checked whether or not the identification code SYID included in the command signal CMND matches the identification code SYID of the ROM 241.

In this case, since they match and the control code CTRL included in the signal CMND indicates a call request, a predetermined protocol is thereafter executed between the handset requesting the call and the base unit 2. Thus, a communication channel is opened between the handset and the base unit 2, and the switch circuit 262 is turned off-hook.

Then, when the telephone number of the other party is input from the dial key 131, this is transmitted to the base unit 2 by the command signal CMND. In the base unit 2, the forming circuit 263 is controlled based on the transmitted command signal CMND. A dial tone signal of the telephone number of the other party is formed, and this dial tone signal is supplied to the line 3 through the conversion circuit 261 and the switch circuit 262.

Therefore, if the other party answers the call thereafter, the call can be made as described above.

Thus, according to this cordless telephone, it is possible to perform outgoing calls, incoming calls, calls, and the like.

And, in this case, especially according to the present invention, when receiving a call,
A plurality of handsets 1A to 1C are designated, and the command signal CMND of the incoming call request is transmitted in order, and only the designated handset returns the command signal CMND of the incoming call response. 1A ~
1C can simultaneously avoid the radio wave collision due to returning the command signal CMND of the incoming call response, and in a short time, that is, within 4 seconds by steps 612 to 618 and 621 to 623, the handset and the base unit 2 and a call channel can be opened.

Also, as shown in FIG. 3, an unmodulated signal section is provided before and after the FM signal Su of the command signal CMND of the incoming response, and at the time of the incoming call, the plurality of handsets 1A to 1C are sequentially arranged, and Since the FM signal Su of the control channel is transmitted without any gap, the radio wave of another cordless telephone can be prevented from interrupting the control channel, and the incoming call processing can be reliably performed.

In the above description, the cordless telephone is a low power type, but when a control channel is not used as in a weak type or a cordless telephone in the U.S.A., an arbitrary channel is regarded as a control channel. Incoming call processing can be performed.

H Advantageous Effects of the Invention According to the present invention, a plurality of handsets 1A to 1A
The handset is designated for 1C, and the command signal CMND for the incoming call request is transmitted in order, and since only the designated handset returns the command signal CMND for the incoming call response, a plurality of handsets 1A to 1C It is possible to avoid radio wave collision caused by returning the command signal CMND of the incoming call response and open a communication channel between the handset and the base unit 2 in a short time.

Also, as shown in FIG. 3, an unmodulated signal section is provided before and after the FM signal Su of the command signal CMND of the incoming response, and at the time of the incoming call, the plurality of handsets 1A to 1C are sequentially arranged, and Since the FM signal Su of the control channel is transmitted without any gap, the radio wave of another cordless telephone can be prevented from interrupting the control channel, and the incoming call processing can be reliably performed.

[Brief description of the drawings]

FIG. 1 is a system diagram of an example of the present invention, FIG. 2 is a diagram showing an example of a signal format thereof, FIG. 3 is a diagram showing an example of transmission timing at the time of an incoming call, and FIG. FIG. 5 and FIG. 6 are flowcharts showing an example of the incoming call routine. 1, 1A to 1C; handset 2; base unit 3: telephone line 110; transmitting circuit 111; transmitter 120; receiving circuit 121; receiver 140; microcomputer 210; transmitting circuit 220; receiving circuit 240; Line / wire conversion circuit 500, 600; Calling routine CMND; Command signal SYID, HSID; Identification code

Continuation of the front page (56) References JP-A-62-48137 (JP, A) JP-A-1-135164 (JP, A) JP-A-1-232843 (JP, A) JP-A-60-136436 (JP, A) , A) (58) Fields surveyed (Int. Cl. ⁷ , DB name) H04M 1/72

Claims (1)

(57) [Claims] 1. A cordless telephone having a master unit connected to a line and a slave unit connected to the master unit via a communication channel during a call, wherein the master unit is connected to a plurality of slave units when a call is received. A command signal for an incoming call request is successively transmitted to each of the slave units by sequentially designating each of the slave units, and the designated slave unit receives the incoming call by specifying the next slave unit by the master unit. During the period when the request command signal is being transmitted, an incoming call response command signal is returned to the master unit, and the master unit transmits the call request command signal in a time-division manner to the slave unit. A cordless telephone which monitors the reception of the command signal of the incoming call response from the remote controller, and makes the connection request to the slave unit which can receive the command signal of the incoming call request by the reception monitor.