Digital cordless telephone set

Details Digital cordless telephone set Digital cordless telephone set

1998-02-11

2001-08-28

Bost, Dwayne (Department: 2681)

Telecommunications

Transmitter and receiver at same station

Radiotelephone equipment detail

C455S573000

Reexamination Certificate

active

06282432

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a digital cordless telephone set and, more particularly, to a digital cordless telephone set capable of simultaneously waiting for a radio wave from a radio base station connected to a public line and a radio wave from a master unit connected from a private line and automatically controlling incoming call wait periods for the respective radio waves.
2. Description of the Prior Art
Conventionally, a cordless telephone set of this type, e.g., a cordless telephone set disclosed in Japanese Unexamined Patent Publication No. 8-237746 shown in
FIG. 1
has a control section
23
which automatically selects connection of a subsidiary unit
21
to a radio base station or a master unit depending on whether the subsidiary unit
21
is placed on a charging unit
22
. Upon detecting that the subsidiary unit
21
is placed on the charging unit
22
, the line to be connected to the subsidiary unit
21
is set to a private line: otherwise, a public line is set as the line to be connected to the subsidiary unit
21
, thereby performing switching control.
Additionally, as disclosed in Japanese Unexamined Patent Publication No. 8-172666, in an area where a radio wave from the radio base station of the private system can be received, the telephone set waits for a ringing signal from the radio base station of the private system. In an area where a radio wave from the radio base station of the public system can be received, the telephone set waits for a ringing signal from the radio base station of the public system. In an area where the radio waves from the radio base stations of both the public and private systems can be received, the telephone set waits for ringing signals from both the public and private systems.
In these prior arts, on the basis of whether the subsidiary unit is within the area where the radio wave from the radio base station connected to the public line or the radio base station (to be referred to as a master unit hereinafter) connected to the private line can be received or whether the subsidiary unit is placed on the charger, the telephone set determines to wait for the radio wave from the radio base station connected to the public line, the radio wave from the master unit connected to the private line, or the radio waves from both systems.
However, when the telephone set is to wait for both the radio wave from the radio base station connected to the public line and that from the master unit connected to the private line, the current consumption during the wait state is higher than that during which the telephone set is waiting for only one of the radio waves, so the continuous waitable time is shortened.
This is because the wait operation for the radio wave from the radio base station connected to the public line and the wait operation for the radio wave from the master unit connected to the private line are simply simultaneously performed (FIG.
2
). Reference symbol Wt in
FIG. 2
represents the period for waiting for the radio wave.
SUMMARY OF THE INVENTION
The present invention has been made in consideration of the above situation of the prior art, and has as its object to provide a subsidiary unit of a digital cordless telephone set which can minimize the current consumption in simultaneously waiting for a radio wave from a radio base station connected to a public line and that from a master unit connected to a private line when both the radio waves can be received.
In order to achieve the above object, according to the first aspect of the present invention, there is provided a digital cordless telephone set as a subsidiary unit, comprising a receiver capable of receiving both a radio wave from a radio base station and a radio wave from a master unit, means for detecting that both the radio wave from the radio base station and the radio wave from the master unit can be received, means for switching between whether only one of the radio wave from the radio base station and the radio wave from the master unit is received and whether both the radio waves are simultaneously received, means for detecting whether the subsidiary unit is placed on a charger, and means for assigning one of a private line and a public line to a priority system and the other to a nonpriority system.
According to the second aspect of the present invention, there is provided a digital cordless telephone set of the first aspect, wherein when it is detected that the subsidiary unit is placed on the charger, the private line is assigned to the priority system and the public line is assigned to the nonpriority system, and when the subsidiary unit is not placed on the charger, the public line is assigned to the priority system and the private line is assigned to the nonpriority system.
According to the third aspect of the present invention, there is provided a digital cordless telephone set of the first aspect, wherein incoming call wait periods of the priority system and the nonpriority system are changeable.
According to the fourth aspect of the present invention, there is provided a digital cordless telephone set of the first aspect, wherein the telephone set has a function of automatically controlling incoming call wait periods of the priority system and the nonpriority system.
As is apparent from the above description, the first effect of the present invention is that when the subsidiary unit of the digital cordless telephone set can receive both the radio wave from the radio base station connected to the public line and that from the master unit connected to the private line, the radio wave from the line which is more likely to receive a call can be effectively waited for.
This is because the sensor detects whether the subsidiary unit is placed on the charger, and when the subsidiary unit is placed on the charger, the radio wave from the master unit connected to the private line is preferentially waited for, and when the subsidiary unit is not placed on the charger, the radio wave from the radio base station connected to the public line is preferentially waited for.
The second effect of the present invention is that when the subsidiary unit of the digital cordless telephone set can receive both the radio wave from the radio base station connected to the public line and that from the master unit connected to the private line, the continuous waitable time can be made longer than that in the prior art while simultaneously waiting for both the radio waves.
This is because when one of the public line and the private line is assigned to the priority system and the other to the nonpriority system on the basis of detection information from the sensor to set the incoming call wait period of the nonpriority system to be longer than the normal period, the frequency of turning on the main power supply of the subsidiary unit can be decreased to minimize current consumption in the incoming call wait mode.
The above and many other objects, features and additional advantages of the present invention will become manifest to those versed in the art upon making reference to the following detailed description and accompanying drawings in which preferred embodiments incorporating the principles of the present invention are shown by way of illustrative examples.


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