JP2015059851A - Time correction device, time correction method, and computer program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology for more shortening time required for the correction of time without generating backtracking in time.SOLUTION: The time correction device includes: a reference clock section 11 for clocking reference time; a device clock section 12 for clocking device time; a check time detection section 13 for detecting check time; and a time correction section 14 for, when the check time arrives, comparing the reference time with the device time, and for, when the device time delays from the reference time, inputting the reference time to the device clock section 12 to set the reference time as the device time, and for, when the device time advances from the reference time, allowing the device clock section 12 to stop to clock the device time only in a period of a difference between the reference time and the device time.

Description

  The present invention relates to a technique for correcting time in a computer system.

  In a computer system, if a backward movement occurs at the time stored in the computer system, it may cause a malfunction. Therefore, in such a computer system, when there is a difference between the internal time and the actual time, it is usually corrected so that the time does not return.

  It is well known to use NTP (Network Time Protocol) for such time correction. In NTP, a slew mode for gradually synchronizing time is prepared. By specifying the slew mode, the NTP client can correct the time without going back even if the internal time is ahead of the actual time notified from the NTP server.

  A technique related to such time correction is described in Patent Document 1. In this related technique, the period of the pulse signal for measuring the internal time is made variable in accordance with the error between the internal time and the actual time. Specifically, in the related technique, when there is no error, a normal pulse generator that generates a pulse having a normal cycle is selected and input to the time device. Also, in this related technique, if the internal time is delayed from the actual time, a delay correction pulse generator that generates a pulse shorter than the normal cycle (for example, 1/2 times) is selected and input to the time device. . In this related technique, if the internal time is ahead of the actual time, the advance correction pulse generator that generates a pulse longer than the normal period (for example, twice) is selected and input to the time device.

Japanese Patent Publication No.62-37354

  However, the related art described above has the following problems.

  In the case of NTP generally used, the correction in the slew mode is set to 0.5 ms (millisecond) per second. Therefore, for example, when an error of 1 second occurs between the internal time and the actual time, the NTP client requires 2000 seconds (33 minutes and 20 seconds) to complete the time correction. For example, it is assumed that a leap second has occurred with no error between the internal time and the actual time. In this case, the NTP client is in a state where the error from the actual time cannot be resolved for 33 minutes and 20 seconds after an error of 1 second due to leap seconds occurs.

  Further, in the related art described in Patent Document 1, when the internal time is ahead of the actual time, a pulse longer than the normal cycle is input to the time device, so that the time longer than the error is eliminated before the error is eliminated. Cost. For example, when the advance correction pulse generator generates a pulse having a period twice as normal, this related technique requires a correction time of 2 seconds to correct the advance of 1 second.

  Thus, these related techniques have a problem that the time required for time correction is long.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a technique for further shortening the time required for time correction without causing a time return.

  The time correction device according to the present invention has a reference clock unit for measuring the reference time, a device clock unit for measuring the device time, and a check time set to check whether or not to perform time correction processing. The check time detection unit to detect, the reference time and the device time are compared with the check time, and when the device time is delayed from the reference time, the reference time is input to the device clock unit A time correction unit configured to stop the time measurement by the device clock unit during a difference period between the reference time and the device time when the device time is ahead of the reference time.

  In addition, the time correction method of the present invention compares the reference time and the device time when the set check time is reached by using the reference clock unit that measures the reference time and the device clock unit that measures the device time. When the device time is delayed from the reference time, the reference time is input to the device clock unit as the device time, and when the device time is ahead of the reference time, the reference time and the The time counting by the device clock unit is stopped only during the difference of the device time.

  Further, the computer program of the present invention uses a reference clock unit that counts the reference time and a device clock unit that counts the device time, so that a check time set to check whether or not to perform time correction processing is checked. A check time detecting step for detecting that the reference time and the device time are compared with the check time, and if the device time is delayed from the reference time, the reference time is set to the device clock unit. And the time correction step of stopping the time measurement by the device clock unit only during the period of difference between the reference time and the device time when the device time is ahead of the reference time. Cause the computer device to execute.

  The present invention can provide a technique for further reducing the time required for correcting the time without causing a time return.

It is a block diagram which shows the structure of the time correction apparatus as the 1st Embodiment of this invention. It is a flowchart explaining operation | movement of the time correction apparatus as the 1st Embodiment of this invention. It is a block diagram which shows the structure of the time correction apparatus as the 2nd Embodiment of this invention. It is a block diagram explaining an example of a structure of the time correction part in the 2nd Embodiment of this invention. It is a flowchart explaining the time correction operation | movement of the time correction apparatus as the 2nd Embodiment of this invention. It is a flowchart explaining the apparatus time read-out response operation | movement of the time correction apparatus as the 2nd Embodiment of this invention. It is a figure explaining an example of the operation | movement which the time correction apparatus as the 2nd Embodiment of this invention correct | amends the delay of apparatus time. It is a figure explaining an example of the operation | movement which the time correction apparatus as the 2nd Embodiment of this invention correct | amends advance of apparatus time. It is a figure explaining an example of the operation | movement which the time correction apparatus as the 2nd Embodiment of this invention correct | amends advance of the apparatus time by insertion of leap second.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration of a time correction apparatus 1 as a first embodiment of the present invention. In FIG. 1, the time correction device 1 includes a reference clock unit 11, a device clock unit 12, a check time detection unit 13, and a time correction unit 14.

  The reference clock unit 11 measures the reference time. The reference time is a reference time when correcting the device time in the device clock unit 12 described later. For example, the reference clock unit 11 may generate information representing the reference time by measuring time based on time data received from an external NTP server at an arbitrary timing. In addition, the reference clock unit 11 measures time with a clock signal input from a pulse generator (not shown).

  The device clock unit 12 measures the time (device time) in the device itself. In addition, the device clock unit 12 measures time with a clock signal input from a pulse generator (not shown).

  The check time detection unit 13 holds the time (check time) at which the time correction process is executed next by the time correction unit 14 described later. Then, the check time detection unit 13 detects that the reference time has reached the held check time, and notifies the time correction unit 14 of it. For example, when the reference time in the reference clock unit 11 becomes equal to the held check time, the check time detection unit 13 may transmit a signal indicating that the check time has been reached to the time correction unit 14. Good.

  The time correction unit 14 is configured to compare the reference time and the device time when the check time comes and to perform time correction processing based on the comparison result. Specifically, when the device time is delayed from the reference time, the time correction unit 14 inputs the reference time to the device clock unit 12 and sets it as the device time. In addition, when the device time is ahead of the reference time, the time correction unit 14 stops the time measurement by the device clock unit 12 only during the difference between the reference time and the device time.

  The operation of the time correction apparatus 1 configured as described above will be described with reference to FIG.

  In FIG. 2, first, the check time detector 13 sends a signal to the time corrector 14 when the reference time reaches the check time (Yes in step S1).

  Next, the time correction unit 14 compares the reference time with the device time (step S2).

  Here, when the device time is delayed from the reference time, the time correction unit 14 inputs the reference time to the device clock unit 12 and sets it as the device time (step S3).

  On the other hand, when the device time is ahead of the reference time, the time correction unit 14 stops the time measurement by the device clock unit 12 only during the difference between the reference time and the device time (step S4).

  Above, description of operation | movement of the time correction apparatus 1 is complete | finished.

  Next, effects of the first exemplary embodiment of the present invention will be described.

  The time correction apparatus as the first embodiment of the present invention can further reduce the time required for time correction without causing a time return.

  The reason is that when the reference clock unit measures the reference time, the device clock unit measures the device time, and when the check time detection unit detects that the reference time is the check time, the time correction unit If the device time is delayed from the reference time, the reference time is input to the device clock unit as the device time, and if the device time is ahead of the reference time, the difference between the reference time and the device time This is because the time counting by the device clock unit is stopped only during the period of time.

  Thereby, this embodiment can immediately correct the apparatus time to the reference time when the apparatus time is delayed from the reference time. Further, in the present embodiment, when the device time is ahead of the reference time, the device time can be corrected to the reference time in the difference period. As a result, the present embodiment can significantly reduce the time required for correction as compared to the above-described related art that requires a longer time than the difference between the reference time and the apparatus time.

(Second Embodiment)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings. Note that, in each drawing referred to in the description of the present embodiment, the same reference numerals are given to the same configuration and steps that operate in the same manner as in the first embodiment of the present invention, and the detailed description in the present embodiment. Description is omitted.

  The structure of the time correction apparatus 2 as the 2nd Embodiment of this invention is shown in FIG. In FIG. 3, the time correction device 2 includes a time correction unit 24 instead of the time correction unit 14 with respect to the time correction device 1 as the first embodiment of the present invention, and further includes a leap second correction unit 25. Is different.

  When the leap second correcting unit 25 detects that a leap second is scheduled to occur before the next check time, the leap second correcting unit 25 sets the estimated occurrence time as a new check time in the check time detecting unit 13. Then, the leap second correction unit 25 corrects the reference time output from the reference clock unit 11 based on the planned leap second generation content.

  For example, the leap second correction unit 25 can detect whether a leap second is inserted or deleted based on a LI (Leap Indicator) bit included in time data (NTP packet) received from an NTP server. It is. Further, the leap second correction unit 25 can detect the leap second occurrence scheduled time based on the time indicated by the NTP packet in which the LI bit is set. This is because leap second insertion or deletion occurs in the last second of the day in UTC (Coordinated Universal Time) and the LI bit is set from 24 hours ago.

  In addition, when the leap second correction unit 25 detects that a leap second is inserted, the leap second correction unit 25 may output a value obtained by subtracting one second from the reference time output from the reference clock unit 11 as the time after the leap second correction. . When the leap second correction unit 25 detects that the leap second is deleted, the leap second correction unit 25 outputs a value obtained by adding 1 second to the reference time output from the reference clock unit 11 as the time after the leap second correction. That's fine.

  In addition, the leap second correction part 25 should just output the reference | standard time output from the reference | standard timepiece part 11 as it is, when the generation plan of leap second is not detected.

  The time correction unit 24 is configured in substantially the same manner as the time correction unit 14 in the first embodiment of the present invention, but differs in the following two points.

  When the time correction unit 24 operates based on the comparison result between the reference time and the device time, the reference time corrected by the leap second correction unit 25 is used as the reference time.

  The time correction unit 24 is configured to operate as follows when there is a device time read request to the device clock unit 12 while the device clock unit 12 stops timing. Specifically, the time correction unit 24 causes the device clock unit 12 to advance the device time held at that time by a predetermined unit and then responds to the read request. Then, the time correction unit 24 extends the stop period of time measurement by the device clock unit 12 by the same length as the device clock time is advanced in the device clock unit 12.

  For example, the time correction unit 24 may be configured as shown in FIG. 4, the time correction unit 24 includes a comparator 241, a timer input selector 242, a timer 243, a comparator 244, a clock selector 245, and a device clock unit input selector 246. In FIG. 4, for convenience of the drawing, the device clock unit 12 is shown inside the broken line graphic indicating the time correction unit 24, but the time correction unit of the present invention does not necessarily indicate that the device clock unit is included. is not.

  When the check time detection signal (enable signal) is input from the check time detection unit 13, the comparator 241 compares the reference time output from the leap second correction unit 25 and the device time output from the device clock unit 12. To do. Then, the comparator 241 outputs a delay signal indicating that the device time is delayed from the reference time or an advance signal indicating that the device time is advanced, and a signal indicating a difference between the reference time and the device time when the device time is advanced. To do. Note that the comparator 241 may not output these signals when the reference time and the apparatus time are equal.

  The timer input selector 242 inputs the advance signal and difference signal from the comparator 241, or the addition signal and subtraction signal for the timer value of the timer 243 to the timer 243.

  The timer 243 uses the difference indicated by the difference signal from the comparator 241 as an initial value of the timer value and performs subtraction until the timer value becomes zero. The timer 243 outputs the timer value to the comparator 244. The timer 243 adds the timer value by a predetermined unit when a device time read signal is input during subtraction of the timer value. In FIG. 4, the minimum unit of 1 ms corresponding to the operating frequency of 1 kHz of the apparatus time is added as a predetermined unit.

  The comparator 244 inputs a clock stop signal to the clock selector 245 when the timer value is greater than zero. Further, when the timer value is larger than 0, the comparator 244 outputs a subtraction signal (“−1 ms (millisecond)” in FIG. 4) indicating that the subtraction is continued to the timer 243.

  The clock selector 245 outputs an externally input clock signal (1 kHz (kilohertz) in FIG. 4) to the device clock unit 12 via the device clock unit input selector 246. Thereby, the device clock unit 12 measures the device time by incrementing the device time by 1 ms. Further, when the clock stop signal from the comparator 244 is input, the clock selector 245 does not output the clock signal. As a result, the device clock unit 12 stops measuring the device time. The clock selector 245 outputs a clock signal for one time when a device time read signal is input when a clock stop signal is input. Thereby, the device clock unit 12 advances the device time by the minimum unit of time (1 ms in FIG. 4) in response to the device time read request even when the time measurement is stopped.

  When the delay signal from the comparator 241 is input, the device clock unit input selector 246 outputs the reference time from the leap second correction unit 25 to the device clock unit 12. Thereby, the device time held by the device clock unit 12 becomes the same as the reference time.

  The operation of the time correction apparatus 2 configured as described above will be described with reference to FIGS.

  First, the time correction process of the time correction apparatus 2 is shown in FIG.

  In FIG. 5, first, the leap second correction unit 25 detects that a leap second is scheduled to occur before the check time set in the check time detection unit 13 (Yes in step S <b> 11). As described above, the leap second correction unit 25 may detect the occurrence schedule of leap seconds based on the LI bit of the NTP packet received from the outside.

  Next, the leap second correction unit 25 sets the leap second generation scheduled time in the check time detection unit 13 as a new check time. Further, the leap second correction unit 25 corrects the reference time output from the reference clock unit 11 based on the scheduled generation contents (insertion or deletion) of the leap second (step S12). As described above, the leap second correction unit 25 outputs a value obtained by subtracting 1 second from the reference time when leap seconds are inserted, and a value obtained by adding 1 second to the reference time when leap seconds are deleted. Should be output.

  Next, when the reference time output from the leap second correction unit 25 becomes the check time, the check time detection unit 13 sends an enable signal to the time correction unit 24 (Yes in step S13).

  Next, the time correction unit 24 compares the reference time after leap second correction and the device time (step S14).

  Specifically, the comparator 241 compares the reference time output from the leap second correction unit 25 and the device time output from the device clock unit 12, and advances the advance signal or the delay signal as the comparison result. In this case, a difference signal is output. As described above, the comparator 241 does not output these signals when the reference time and the apparatus time are equal.

  Here, when the device time is delayed from the reference time from the leap second correction unit 25, the time correction unit 24 inputs the reference time from the leap second correction unit 25 to the device clock unit 12 and sets it as the device time. (Step S15).

  Specifically, when a delay signal is output from the comparator 241 and input to the device clock unit input selector 246, the device clock unit input selector 246 sets the reference time from the leap second correction unit 25 as the device clock unit 12. Output for.

  On the other hand, when the device time is ahead of the reference time from the leap second correction unit 25, the time correction unit 24 uses the device clock unit 12 only during the difference between the reference time from the leap second correction unit 25 and the device time. Timekeeping is stopped (step S16).

  Specifically, when the advance signal and the difference signal are input from the comparator 241 to the timer 243 via the timer input selector 242, the timer 243 starts subtraction until the timer value becomes 0 with the difference signal as an initial value. To do. When the timer value is greater than 0, the comparator 244 outputs a clock stop signal to the clock selector 245 and stops supplying the clock to the device clock unit 12. When the timer value of the timer 243 reaches 0, the comparator 244 stops outputting the clock stop signal and starts supplying the clock to the device clock unit 12.

  Above, description of a time correction process is complete | finished.

  Next, device time read response processing of the time correction device 2 is shown in FIG.

  In FIG. 6, first, the time correction unit 24 receives a device time read request (Yes in step S <b> 21).

  Next, the time correction unit 24 advances the device time held by the device clock unit 12 by a predetermined unit when the time measurement by the device clock unit 12 is stopped (Yes in step S22), and the timing stop period. Is extended by a predetermined unit (step S23).

  Specifically, when the timer 243 receives the device time read signal when the timer value is greater than 0, the timer 243 adds the timer value by a predetermined unit. Here, since the timer 243 is subtracting the timer value, the timer 243 performs subtraction and addition. Therefore, the timer value becomes plus or minus 0 and does not change.

  And the time correction apparatus 2 should just respond with the apparatus time which advanced only the predetermined unit by step S23.

  This is the end of the description of the apparatus time read response process.

  Next, the operation of the time correction device 2 will be shown as a specific example. Here, it is assumed that the operating frequency of the reference clock unit 11 and the device clock unit 12 is 1 KHz.

<Example of operation when there is no leap second and the device time is behind the reference time>
First, the operation of the time correction apparatus 2 when there is no occurrence of leap seconds and the apparatus time is delayed by 1 second from the reference time will be described with reference to FIG. Since the occurrence of leap seconds is not detected, the reference time output from the leap second correction unit 25 is the same as the reference time before correction that the reference clock unit 11 measures.

  Here, the check time detection unit 13 is set with 9: 00: 00: 000 ms (hereinafter, the numerical value in milliseconds is omitted and described as 9:00: 00) as the check time. To do.

  First, when the reference time reaches 9:00: 00, the check time detection unit 13 outputs an enable signal to the comparator 241 (Yes in step S13).

  Next, the comparator 241 compares the apparatus time (8:59:59) with the reference time (9:00:00) and outputs a delay signal (“delayed” in step S14).

  Then, the device clock unit input selector 246 outputs the reference time from the leap second correction unit 25 to the device clock unit 12, and the device clock unit 12 continues to count time using the reference time as the device time (step S15).

  As a result, the device time of the device clock unit 12 becomes the same as the reference time of the reference clock unit 11, and the delay of the device clock unit 12 is corrected.

<Example of operation when no leap second occurs and the device time is ahead of the reference time>
Next, the operation of the time correction apparatus 2 when there is no leap second occurrence and the apparatus time is advanced by 2 seconds from the reference time will be described with reference to FIG. Since the occurrence of leap seconds is not detected as in the above-described specific example, the reference time output from the leap second correction unit 25 is the same as the reference time before correction counted by the reference clock unit 11.

  Similarly to the above-described specific example, it is assumed that 9:00:00 is set as the check time in the check time detection unit 13.

  First, when the reference time reaches 9:00: 00, the check time detection unit 13 outputs an enable signal to the comparator 241 (Yes in step S13).

  Next, the comparator 241 compares the device time (9:00:02) with the reference time (9:00:00), and compares the advance signal with the difference representing the difference between the reference time and the device time (2 seconds). The signal is output (“advance” in step S14).

  Then, the timer 243 starts subtraction of 1 ms using the difference (2 seconds) as the initial value of the timer value. The comparator 244 outputs a clock stop signal while the value of the timer value output from the timer 243 is greater than 0, and stops the supply of the clock signal to the device clock unit 12 (step S16). For this reason, the device clock unit 12 stops stepping by 1 ms. The comparator 244 stops outputting the clock stop signal when the value of the timer value output from the timer 243 becomes 0, and starts supplying the clock signal to the device clock unit 12. For this reason, the device clock unit 12 resumes stepping by 1 ms.

  As a result, the device clock unit 12 stops timing for 2 seconds, which has been advanced with respect to the reference time, and the advance is corrected.

<Operation example when responding to reading of device time while device clock unit 12 stops measuring time>
Next, the operation when the device time is read while the device clock unit 12 stops timing will be described.

  First, the clock selector 245 supplies a clock for one time to the device clock unit 12 when receiving a device time read signal while the time is stopped (when a clock stop signal is input). Thereby, the device clock unit 12 advances the device time by 1 ms.

  At the same time, the timer 243 adds 1 ms to the timer value. Here, the timer 243 performs subtraction (−1 ms) of the timer value. Therefore, the timer value becomes ± 0 ms, and the period until the timer value becomes 0 is extended by 1 ms.

  As described above, the device clock unit 12 updates the device time by 1 ms every time the device time is read even when the time measurement is stopped, and thus guarantees the order of reading the device time. In addition, since the timer 243 extends the timer period by 1 ms every time the apparatus time is updated by 1 ms in response to the reading of the apparatus time during the time stop, the period for correcting the advance is consistent.

<Operation example when there is no error in device time and reference time and leap second insertion is planned>
Next, an operation in the case where a leap second is scheduled to occur will be described with reference to FIG.

  First, the leap second correction unit 25 detects that a leap second is scheduled to be inserted by the check time set in the check time detection unit 13 (Yes in step S11). It is assumed that the leap second insertion time is immediately before 9:00.

  Therefore, the leap second correction unit 25 sets 9:00: 00 immediately after the occurrence of leap second insertion as a new check time in the check time detection unit 13. Further, the leap second correction unit 25 outputs a value obtained by subtracting one second from the reference time output from the reference clock unit 11 (step S12).

  When the reference time output from the leap second correction unit 25 reaches 9: 00: 00: 00, the check time detection unit 13 outputs an enable signal to the comparator 241 (Yes in step S13).

  Next, the comparator 241 compares the device time (9:00:01) with the reference time (9:00:00) output from the leap second correction unit 25, and compares the advance signal and the difference signal (1 second). ) Is output (“advance” in step S14).

  Next, the timer 243 starts subtraction of 1 ms using the difference (1 second) as a timer value. Then, by operating in the same manner as in the above-described “example of operation when the leap second does not occur and the device time is ahead of the reference time”, the device clock unit 12 increments by 1 ms for 1 second. Stop and then resume (step S16).

  As a result, the time correction device 2 can start correcting the error by inserting a leap second between the actual time and the device time immediately after the occurrence of the leap second, and can complete the correction in one second.

  This is the end of the description of the specific example.

  Next, the effect of the second exemplary embodiment of the present invention will be described.

  The time correction apparatus according to the second embodiment of the present invention can further reduce the time required to correct leap seconds without causing a time return.

  The reason is that when the leap second correction unit detects that a leap second is scheduled to occur before the next check time, the leap second correction unit sets the expected occurrence time as a new check time in the check time detection unit and sets the reference time as If the device time is delayed from the reference time after the leap second correction based on the comparison between the reference time after the leap second correction and the device time, When the reference time after the second correction is input to the device clock unit as the device time and the device time is ahead of the reference time after the leap second correction, only the difference between the reference time after the leap second correction and the device time, This is because the timing by the device clock unit is stopped.

  Thereby, the present embodiment starts time correction immediately after the occurrence of leap seconds, and in the case of deletion of leap seconds, the apparatus time can be immediately corrected to the reference time after leap second correction. . In the present embodiment, time correction is started immediately after the occurrence of leap seconds. When leap seconds are inserted, the apparatus time is corrected for leap seconds in the inserted leap second period (1 second). It can be corrected to a later reference time.

  In addition, the present embodiment can guarantee the order of the device times read from the own device while stopping the time measurement of the device clock unit to correct the advance of the device time.

  The reason for this is that if the time correction unit makes a request to read the device time while the device clock is stopped due to the advance of the device time, the device time held by the device clock is advanced by a predetermined unit and then responds to the read request. This is because the timing stop period of the device clock section is extended by a predetermined unit.

  As a result, in the present embodiment, the device time is updated by a predetermined unit every time the device time is read out even when the device clock unit stops counting time to correct the advance of the device time. Therefore, this embodiment guarantees the order of the device times to be read. At this time, in this embodiment, every time the device time is updated by a predetermined unit in response to the reading of the device time during the time stop, the time stop period is extended by a predetermined unit, so that the advancement of the device time can be performed without any problem. Can be corrected.

  In the present embodiment, the description has been made centering on an example in which the operating frequency of the reference clock unit and the device clock unit is 1 KHz, but the operating frequency of these clock units is not limited. In addition, although an example in which the unit for advancing the apparatus time is 1 ms when the apparatus time is read while the time is stopped has been described, the predetermined unit for advancing the apparatus time is not limited.

  In the present embodiment, the leap second correction unit has described an example in which the leap second occurrence schedule is detected based on the NTP packet. However, the leap second occurrence schedule is not limited to the NTP packet, and other known techniques are used. May be detected.

  In each of the embodiments of the present invention described above, an example in which the reference clock unit measures the reference time based on time data received from the NTP server has been described. The reference time may be measured based on the time that can be acquired by technology.

  Further, in each of the embodiments of the present invention described above, each functional block of the time correction apparatus has been described mainly with respect to examples configured by hardware elements. However, a part, all, or part of each functional block is described. The combination may be realized by a processor that executes a computer program stored in a memory.

  In each of the embodiments of the present invention described above, the operation of the time correction apparatus described with reference to each flowchart is stored in a storage device (storage medium) of the computer apparatus as a computer program of the present invention. Such a computer program may be read and executed by the CPU. In such a case, the present invention is constituted by the code of the computer program or a storage medium.

  Moreover, each embodiment mentioned above can be implemented in combination as appropriate.

  The present invention is not limited to the above-described embodiments, and can be implemented in various modes.

1, 2 Time correction device 11 Reference clock unit 12 Device clock unit 13 Check time detection unit 14, 24 Time correction unit 25 Leap second correction unit 241 Comparator 242 Timer input selector 243 Timer 244 Comparator 245 Clock selector 246 Device clock unit input selector

Claims (9)

A reference clock for measuring the reference time,
A device clock for measuring device time;
A check time detection unit that detects that a check time set to check whether or not to perform time correction processing is reached;
The reference time and the device time are compared with the check time, and when the device time is delayed from the reference time, the reference time is input to the device clock unit as the device time, and the device time is A time correction unit that stops time counting by the device clock unit for a period of difference between the reference time and the device time when the time is ahead of the reference time;
A time correction apparatus comprising: When it is detected that there is a leap second occurrence schedule by the next check time, the occurrence time is set as a new check time in the check time detection unit, and based on the leap second occurrence schedule content, A leap second correction unit that corrects the reference time is further provided.
The time correction device according to claim 1, wherein the time correction unit uses the reference time corrected by the leap second correction unit as the reference time.   The time correction unit advances the device time held by the device clock unit by a predetermined unit when there is a request for reading the device time while the device clock unit is stopped, and the timing stop period of the device clock unit. The time correction device according to claim 1, wherein the time is extended by the predetermined unit. Using a reference clock unit that measures the reference time and a device clock unit that measures the device time,
When the set check time is reached, the reference time and the device time are compared, and if the device time is behind the reference time, the reference time is input to the device clock unit as the device time, A time correction method in which, when the device time is ahead of the reference time, the time measurement by the device clock unit is stopped only during a difference between the reference time and the device time. When it is detected that there is a leap second occurrence by the next check time, the occurrence occurrence time is set as a new check time,
Correct the reference time based on the planned occurrence of leap seconds,
5. The time correction method according to claim 4, wherein a reference time corrected on the basis of the planned content of the leap second is used as the reference time in the processing performed when the check time is reached.   If there is a request to read the device time while the device clock is stopped, the device time held by the device clock is advanced by a predetermined unit, and the time stop period of the device clock is extended by the predetermined unit. The time correction method according to claim 4 or 5, wherein: Using a reference clock unit that measures the reference time and a device clock unit that measures the device time,
A check time detection step for detecting that a check time set to check whether or not to perform time correction processing is reached;
The reference time and the device time are compared with the check time, and when the device time is delayed from the reference time, the reference time is input to the device clock unit as the device time, and the device time is If the time is ahead of the reference time, a time correction step of stopping the time measurement by the device clock unit only for the difference between the reference time and the device time; and
Is a computer program that causes a computer device to execute. When it is detected that a leap second is scheduled to occur before the next check time, the occurrence time is set as a new check time, and the reference time is corrected based on the details of the leap second occurrence. Further causing the computer device to execute a second correction step;
The computer program according to claim 7, wherein, in the time correction step, a reference time corrected based on the planned leap second content is used as the reference time.   In the time correction step, when there is a request for reading the device time during the time stop of the device clock unit, the device time held in the device clock unit is advanced by a predetermined unit, and the time stop period of the device clock unit is 9. The computer program according to claim 7, wherein the computer program is extended by the predetermined unit.

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