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

• US 20020116658A1
• Filed: 02/13/2002
• Published: 08/22/2002
• Est. Priority Date: 02/16/2001
• Status: Active Grant

• Current Assignee: Lenovo Innovations Ltd Hong Kong (Lenovo Group Ltd.)
• Original Assignee: NEC Corporation
• Inventors: Yano, Masatoshi
• Granted Patent: US 6,938,178 B2
• Time in Patent Office: Days
• US Class Current: 713/600
• 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 obtains information from the first real-time clock when the terminal device is in a first operation mode, and

the control section obtains information from the second real-time clock when the terminal device is in a second operation mode.

2. A terminal device as claimed in claim 1, wherein the second real-time clock is directly connected to the control section by a signal line.

3. A terminal device as claimed in claim 1, wherein the second real-time clock is connected to the control section via a functional device.

4. A terminal device as claimed in claim 1, wherein the second real-time clock is built in a functional device which is connected to the control section.

5. A terminal device as claimed in claim 1, wherein the information obtained from the second real-time clock is transferred to the first real-time clock and thereafter the control section obtains the information from the first real-time clock.

6. A terminal device as claimed in claim 5, wherein the information of the first real-time clock is restored by use of the information transferred from the second real-time clock.

7. A terminal device as claimed in claim 1, wherein the control section and the second real-time clock are powered by different power sources.

8. A terminal device as claimed in claim 1, wherein the information at least includes time information and date information.

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

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

the second operation mode is enabled when the control section recovered from failure.

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

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

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

a first information obtaining step in which a control section of the terminal device obtains information from a first real-time clock which is built in the control section if the terminal device is in the first operation mode, and

a second information obtaining step in which the control section obtains information from a second real-time clock which is provided outside the control section if the terminal device is in the second operation mode.

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, wherein the information obtained from the second real-time clock is transferred to the first real-time clock and thereafter the control section obtains the information from the first real-time clock.

16. A method as claimed in claim 15, wherein the information of the first real-time clock is restored by use of the information transferred from the second real-time clock.

17. A method as claimed in claim 11, wherein the control section and the second real-time clock are powered by different power sources.

18. A method as claimed in claim 11, wherein the information at least includes time information and date information.

19. A method as claimed in claim 11, wherein:

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

the second operation mode is enabled when the control section recovered from failure.

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