Terminal device and real-time clock control method therefor enabling preservation of clock/calendar information and high information readout speed

• US 6,938,178 B2
• Filed: 02/13/2002
• Issued: 08/30/2005
• Est. Priority Date: 02/16/2001
• Status: Expired due to Fees

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Yano, Masatoshi
• Primary Examiner(s): BUTLER, DENNIS
• Application Number:
  US10/073,161
• Publication Number:
  US 20020116658A1
• Time in Patent Office: 1,294 Days
• Field of Search: 713/1, 713/2, 713/100, 713/400, 713/500, 713/502, 713/503, 713/600
• US Class Current: 713/500
• CPC Class Codes: G06F 1/14 Time supervision arrangements, e.g. real time clock

Abstract

A terminal device such as a mobile terminal is provided with two real-time clocks which are powered by different power sources: a first real-time clock which is built in a control section (built-in microcomputer 1, for example) of the terminal device; and a second real-time clock which is provided outside the control section. At power-on of the mobile terminal or on recovery from failure such as a power cut, clock/calendar information is read out from the second real-time clock and is set to the first real-time clock, and thereafter, the control section obtains the clock/calendar information from the first real-time clock. The second real-time clock is connected to the control section directly by a signal line or via a functional device, or the second real-time clock is built in a functional device which is connected to the control section. By such composition and operation, the clock/calendar information can be maintained reliably and correctly even if failure occurred to the control section. The readout of the clock/calendar information is carried out usually from the first real-time clock (built-in RTC), therefore, high readout speed can be realized.

Claims

1. A terminal device comprising:

a control section for controlling the terminal device;

a first real-time clock which is built in the control section; and

a second real-time clock which is provided outside the control section, wherein;

the control section is further responsive to the terminal device being in a first operation mode to obtain real-time information from the first real-time clock, and

the control section is further responsive to the terminal device being in a second operation mode to obtain real-time information from the second real-time clock.

2. A terminal device as claimed in claim 1, further comprising a signal line directly connecting the second real-time clock to the control section.

3. A terminal device as claimed in claim 1, further comprising a functional device connecting the second real-time clock to the control section.

4. A terminal device as claimed in claim 1, further comprising a functional device having the second real-time clock built therein.

5. A terminal device as claimed in claim 1, wherein the control section is further responsive to the terminal device changing from the second operation mode to the first operation mode to transfer the real-time information obtained from the second real-time clock to the first real-time clock and thereafter to obtain the real-time information from the first real-time clock.

6. A terminal device as claimed in claim 5, wherein the control section is further responsive to the real-time information obtained from the second real time clock being transferred to the first real-time clock to restore the real-time information of the first real-time clock by use of the real-time information transferred from the second real-time clock.

7. A terminal device as claimed in claim 1, further comprising a first power source for powering the control section and a second power source for powering the second real-time clock.

8. A terminal device as claimed in claim 1, wherein the real-time information comprises time information and date information.

9. A terminal device as claimed in claim 1, wherein:

the terminal device is responsive to the control section operating normally to enable the first operation mode; and

the terminal device is responsive to the control section operating other than normally to enable the second operation mode.

10. A terminal device as claimed in claim 1, wherein the control section comprises a microcomputer which is built in the terminal device.

11. A method for controlling a real-time clock of a terminal device, comprising:

judging whether the terminal device is in a first operation mode or a second operation mode;

when the terminal device is in the first operation mode, activating a control section of the terminal device to obtain real-time information from a first real-time clock which is built in the control section; and

when the terminal device is in the second operation mode, activating the control section to obtain real-time information from a second real-time clock which is provided outside the control section.

12. A method as claimed in claim 11, wherein the second real-time clock is directly connected to the control section by a signal line.

13. A method as claimed in claim 11, wherein the second real-time clock is connected to the control section via a functional device.

14. A method as claimed in claim 11, wherein the second real-time clock is built in a functional device which is connected to the control section.

15. A method as claimed in claim 11, further comprising, when the terminal device changes from the second operation mode to the first operation mode, transferring the real-time information obtained from the second real-time clock to the first real-time clock, and thereafter obtaining real-time information from the first real-time clock.

16. A method as claimed in claim 15, further comprising restoring the real-time information of the first real-time clock by use of the real-time information transferred from the second real-time clock.

17. A method as claimed in claim 11, further comprising powering the control section by a first power source, and powering the second real-time clock by a second power source.

18. A method as claimed in claim 11, wherein the real-time information comprises time information and date information.

19. A method as claimed in claim 11, further comprising:

when the control section is operating normally, enabling the first operation mode; and

when the control section is operating other than normally, enabling the second operation mode.

20. A method as claimed in claim 11, wherein the control section comprises a microcomputer which is built in the terminal device.