Method of indicating a portable unit of a cordless telephone instrument out of operational area and its device

• US 5,644,620 A
• Filed: 05/26/1995
• Issued: 07/01/1997
• Est. Priority Date: 06/30/1994
• Status: Expired due to Fees

• Current Assignee: NEC Corporation
• Original Assignee: NEC Corporation
• Inventors: Shimura, Yukihiro
• Primary Examiner(s): Kuntz, Curtis
• Assistant Examiner(s): Shankar, Vijay
• Application Number:
  US08/451,677
• Time in Patent Office: 767 Days
• Field of Search: 379/1, 379/32, 379/33, 379/34, 379/58, 379/61, 379/22, 379/24, 379/27, 379/29, 379/30, 455/54.1, 455/54.2, 455/33.1, 455/56.1, 455/229, 455/38.1
• US Class Current: 455/421
• CPC Class Codes: H04M 1/72502 with one base station connected to a single line
• CPC Class Codes: H04M 1/72516 with means for out-of-range alerting

Abstract

A cordless telephone instrument is improved in that, even when a portable unit is not in use, it can be determined and notified to the user whether the portable unit is inside or outside of an operational area of the portable unit. In portable unit 2, portable unit timer 28 counts a predetermined first reference time and outputs a time-out signal for each first reference time. Every time the time-out signal is outputted, a registration signal is transmitted from portable unit radio circuit 21 toward a fixed unit. When the registration signal is received by fixed unit radio section 12, fixed unit 1 transmits a response signal toward portable unit 2. Portable unit 2 continuously operates to receive a response signal. However, when no response signal is detected within a counting time of portable unit timer 28, operational area out alarm generation section 27 is activated under the control of portable unit control circuit 24 to perform an operation of notifying that portable unit 2 is outside of the operational area.

Claims

1. A method of indicating that a portable unit of a cordless telephone instrument which comprises a fixed unit and a portable unit is out of operational area, comprising the steps of:

starting counting of a predetermined first reference time at said portable unit,

transmitting a registration signal of a first frequency peculiar to said cordless telephone instrument from said portable unit after lapse of the predetermined first reference time and starting next counting of the predetermined first reference time by said portable unit;

transmitting, upon reception of the registration signal by a fixed unit, a response signal of a second frequency peculiar to said fixed unit;

resetting, when said portable unit having transmitted the registration signal receives the response signal, the counted value of the first predetermined reference time and starting next counting of the first reference time by said portable unit; and

outputting, when said portable unit receives no response signal after having transmitted the registration signal for more than a predetermined second reference time longer than the predetermined first reference time, an indication of an unavailable situation on said portable unit.

2. A method of indicating that a portable unit of a cordless telephone instrument which comprises a fixed unit and portable unit is out of operational area, comprising the steps of:

starting counting of a predetermined first reference time at said portable unit for every reset;

counting a predetermined second reference time shorter than the predetermined first reference time of a portable unit at the fixed unit, transmitting, after lapse of the predetermined second reference time, a confirmation signal of a first frequency peculiar to said cordless telephone instrument from said fixed unit toward said portable unit and resetting the counted time at said fixed unit to re-start a next counting of the predetermined second reference time;

resetting, when said portable unit receives the confirmation signal, the counting of the predetermined first reference time and starting a next counting of the predetermined first reference time; and

outputting an indication of an unavailable situation on said portable unit when said portable unit counts up the predetermined first reference time and outputs a time-out signal.

3. A cordless telephone instrument which includes a fixed unit, and a portable unit connected to said fixed unit through a radio channel, comprising:

portable unit timer means provided in said portable unit for counting, every time after said portable unit timer means is reset, a predetermined first reference time and outputting a time-out signal when said portable unit timer means counts up the predetermined first reference time;

transmission and reception means provided in said portable unit for transmitting, every time the time-out signal is outputted, a registration signal of a first frequency peculiar to said cordless telephone instrument toward said fixed unit and receiving a response signal from said fixed unit;

means provided in said portable unit for resetting said portable unit timer means when the response signal is received;

means provided in said portable unit for outputting an indication of an unavailable situation on the portable unit when the response signal is not received within the predetermined first reference time; and

means provided in said fixed unit for sending out, when a registration signal is received from said portable unit, a response signal of a second frequency peculiar to the subscriber toward said portable unit.

4. A cordless telephone instrument as claimed in claim 3, wherein said means for outputting an indication of an unavailable situation is an alarm generation section for outputting alarming sound.

5. A cordless telephone instrument as claimed in claim 3, wherein said means for outputting an indication of an unavailable situation is a display of an alarm indication mark.

6. A cordless telephone instrument as claimed in claim 3, wherein said means for outputting an indication of an unavailable situation is means for outputting alarming sound and a display of an indication mark simultaneously.

7. A cordless telephone instrument which includes a fixed unit, and a portable unit connected to said fixed unit through a radio channel, comprising:

portable unit timer means provided in said portable unit for counting, every time after said portable unit timer means is reset, a predetermined first reference time and outputting a time-out signal when said portable unit timer means counts up the predetermined first reference time;

reception means provided in said portable unit for resetting said portable unit timer means when a confirmation signal sent out from said fixed unit is received;

means provided in said portable unit for outputting, when the time-out signal is outputted, an indication of an unavailable condition display representing that said portable unit is in a situation away from said fixed unit;

fixed unit timer means provided in said fixed unit for counting a predetermined second reference time shorter than the predetermined first reference time of said portable unit timer means is reset every time after counting the predetermined second reference time and outputs a time-out signal; and

transmission means provided in said fixed unit for transmitting a confirmation signal of a second frequency peculiar to said cordless telephone instrument toward said portable unit and resetting said fixed unit timer when the time-out signal is outputted from said fixed unit timer means.

8. A cordless telephone instrument as claimed in claim 7, wherein said means for outputting an indication of an unavailable situation display is an alarm generation section for outputting alarming sound.

9. A cordless telephone instrument as claimed in claim 7, wherein said means for outputting an indication of an unavailable situation is a display of an alarm indication mark.

10. A cordless telephone instrument as claimed in claim 7, wherein said means for outputting an indication of an unavailable situation is means for outputting alarming sound and a display of an indication mark simultaneously.