JP2008064495A - Time synchronizing device, system, and method, and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a time synchronizing device, a time synchronizing system, a time synchronizing method, and a program capable of not only performing periodically a timing for performing time synchronization with another device, but also performing time correction at an accurate and optimum timing by the device, by detecting a time abnormality or the like by the device itself, and determining a timing when the time correction (synchronization) is necessary. <P>SOLUTION: This time synchronizing device having a function for taking time synchronization with another device when communicating with another device, has an internal timepiece for measuring a time of own device, a host device time acquisition means for acquiring a time of a host device managing own device, a timing detection means for detecting a timing when time correction of the internal timepiece is necessary, and a time correction means for correcting the time of own device to the time of the host device as time correction of the internal clock when the timing when time correction is necessary is detected by the timing detection means. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a time synchronization device, a time synchronization system, a time synchronization method, and a program for synchronizing time when communicating with other devices.

  Some conventional communication systems have a management device (higher-level device) and a managed device (lower-level device) managed by the management device on a network. Examples of the prior art of such a communication system include the following.

  For example, as disclosed in Patent Document 1, by providing inside a firewall, communication between a management device that is a server provided outside the firewall and a managed device that is a number of clients provided inside the firewall is mediated. When the intermediary device receives a command from each managed device, transfers it to the management device, and accesses the management device, the management device can send a response to any of the commands transferred so far. In this case, there is a “mediation device, communication system, communication method, program, and recording medium” that receives the response and transfers the response to the transmission source of the command corresponding to the response.

  For example, as disclosed in Patent Document 2, when a CPU of an image forming apparatus that is a managed apparatus detects an unusable factor (down factor) within a preset downtime measurement period (predetermined period), the CPU cannot be used. The vendor measures the downtime (unusable time) when the device cannot be used due to the occurrence of a factor, and every time the measured time reaches one of the preset downtime notification thresholds, the vendor There is a "remote management system and its electronic device, control method when unusable factor occurs, and program" to notify the management device on the side.

For example, as Patent Document 3, a management device capable of communicating with a communication device (managed device) that uses a component storing a digital certificate receives a digital certificate together with a communication request from the communication device, and receives the digital certificate. If it is determined that it is necessary to renew the digital certificate for the component, the digital certificate for update is transmitted to the communication device, and the communication device updates the digital certificate for the component. Transfer device, authentication data transfer device, digital certificate setting system, authentication data setting system, communication device control method, digital certificate setting method, authentication data setting method, program, and recording medium ”.
JP 2005-316991 A JP 2005-100304 A JP 2005-318572 A

  However, in the conventional communication systems such as those described in Patent Documents 1 to 3, the time synchronization apparatus has a simple timing at which the time synchronization is performed or only at the time of activation. Therefore, the device itself did not detect that the time was actually abnormal, and time synchronization was not executed.

  The present invention has been made in view of the above circumstances, and not only periodically triggers (timing) to synchronize time with other devices, but also the device itself detects time abnormality and corrects the time. It is an object of the present invention to provide a time synchronization device, a time synchronization system, a time synchronization method, and a program capable of performing time correction at a more accurate and optimal timing by determining an opportunity that requires (synchronization). To do.

  In order to achieve this object, the invention described in claim 1 is a time synchronization device having a function of synchronizing time with another device when communicating with the other device, and measures the time of the device itself. The internal clock, the host device time acquisition means for acquiring the time of the host device that manages the own device, the trigger detection means for detecting the trigger that needs to correct the time of the internal clock, and the clock correction by the trigger detection means. When an opportunity is detected, it has time correction means for correcting the time of its own device to the time of the host device as time correction of the internal clock.

  The invention according to claim 2 is the invention according to claim 1, wherein the trigger detection means compares the time of the host device acquired by the host device time acquisition means with the time of the own device measured by the internal clock. When it is determined whether or not the difference between the two times is within a predetermined allowable time error range, and the difference between the two times is not within the allowable time error range as a result of the determination, the time correction is necessary It is characterized by detecting.

  According to a third aspect of the present invention, in the first or second aspect of the invention, the trigger detection means stores the time when the predetermined information is stored in the storage medium together with the time of the upper apparatus acquired by the upper apparatus time acquisition means. It is detected as an opportunity that requires correction.

  According to a fourth aspect of the present invention, in the invention according to any one of the first to third aspects, the trigger detection means is configured such that the self-device has an expiration date of an electronic certificate held for performing encrypted communication with another device. Is compared with the time of the own device measured by the internal clock to determine whether the time of the own device is within the validity period of the electronic certificate. It is characterized in that a case where the certificate is not within the valid period is detected as an opportunity that requires time correction.

  According to a fifth aspect of the present invention, in the invention according to any one of the first to fourth aspects, the trigger detection means is configured such that when the own apparatus performs encrypted communication with the other apparatus using an electronic certificate, Compares the expiration date of the electronic certificate sent from the device with the time of the device itself measured by the internal clock, and determines whether the time of the device is within the validity period of the electronic certificate. As a result of the determination, a case where the time of the own device is not within the validity period of the electronic certificate is detected as an opportunity that requires time correction.

  The invention according to claim 6 is the invention according to any one of claims 1 to 5, wherein the trigger detection means sends information sent from the lower device during communication with the lower device managed by the own device. The time of the lower device included in the device is compared with the time of the own device measured by the internal clock to determine the time of the lower device, and as a result of the determination, the time of the lower device is greater than the time of the own device. The present invention is characterized in that when it is in the future, or when it is past a predetermined time, it is detected as an opportunity that requires time correction.

  The invention according to claim 7 is the invention according to any one of claims 1 to 6, wherein the trigger detection means includes a time stamp of a packet sent from the other device and an internal Compares the time of the device with the time measured by the clock to determine whether the difference between the two times is within a predetermined allowable time error range. As a result of the determination, the difference between the two times is within the allowable time error range. It is characterized in that a case that is not within is detected as an opportunity that requires time correction.

  The invention according to claim 8 is the invention according to any one of claims 1 to 7, wherein the trigger detection means receives a notification from the other device that the time of its own device is abnormal. It is detected as an opportunity that requires correction.

  The invention according to claim 9 is the invention according to any one of claims 1 to 8, further comprising a timer based on a monotonically increasing clock that is not affected by the internal clock, and the trigger detecting means is a timer based on the monotonically increasing clock. It is characterized by detecting every fixed period measured by the above as a trigger that requires time correction.

  The invention according to claim 10 is the invention according to any one of claims 1 to 9, wherein the trigger detection means detects when the own apparatus is activated as a trigger that requires time correction. To do.

  The invention according to claim 11 is the invention according to any one of claims 1 to 10, further comprising time changing means for accepting a predetermined operation and changing the time of the internal clock. The time change means detects when an operation to change the time and time zone of the internal clock is accepted as an opportunity that requires time correction.

  The invention according to claim 12 is the invention according to any one of claims 1 to 11, wherein the trigger detection means includes a time stamp of a file and a directory stored in a storage medium accessible by the own device, Compare with the time of its own device measured by the internal clock, determine the time stamp of the file and directory, and if the result of the determination is that the time stamp of the file and directory is later than the time of its own device, or Detecting a time that needs to be corrected when it is past the predetermined time.

  According to a thirteenth aspect of the present invention, in the invention according to any one of the first to twelfth aspects, the trigger detection means is measured by the time included in the content of the data held by the own device and the internal clock. Compared with the time of the own device, the time included in the content of the data held by the own device is determined, and as a result of the determination, the time included in the content of the data held by the own device is In this case, it is detected that a time that needs to be corrected is detected when the time is later than the time or when it is past the predetermined time.

  The invention according to claim 14 is the invention according to any one of claims 1 to 13, further comprising response means for responding to an inquiry from a lower device managed by the own device, wherein the trigger detection means is , The time when there is an inquiry from the lower device about the time of its own device is detected as a trigger that requires time correction, the response means from the lower device after the time of the own device is corrected by the time correction means In response to the inquiry, the time of its own device is returned.

  The invention according to claim 15 is the invention according to any one of claims 1 to 14, wherein, as a result of time correction by the time correction means, if the time of the own device is normal, It has the 1st time abnormality notification means which notifies the time abnormality of an apparatus, or the expiration date of the electronic certificate of another apparatus.

  According to a sixteenth aspect of the present invention, in the invention according to any one of the first to fifteenth aspects, if the time of the internal clock has returned to the default as a result of the time correction by the time correction means, It is characterized by having a second time abnormality notification means for detecting an abnormality of the built-in battery for maintaining the internal clock when it is not, and notifying the host device of that fact to that effect.

  The invention according to claim 17 is the invention according to any one of claims 1 to 16, wherein the time correction means calculates the time required for the reception processing during the time inquiry communication to the host device that manages the device. The measurement is performed using a monotonically increasing clock that is not affected by the internal clock, and the time correction is performed after adding the measurement result to the time acquired from the host device as a time lag caused by communication processing.

  The invention according to claim 18 is the invention according to any one of claims 2 to 17, wherein the accuracy of the accuracy of the internal clock and the accuracy of the internal clock of the host device that manages the own device And an allowable time error setting means capable of setting up to ± N (N: a predetermined number) times the minimum number of digits as an allowable time error.

  The invention according to claim 19 is the invention according to any one of claims 1 to 18, wherein when the host device time acquisition means acquires the time of the host device from the host device, the mutual certificate using the electronic certificate is used. By using authentication and encrypted communication, it is characterized by having security means for protecting the legitimacy of the time of the host device and preventing falsification of the time of the host device.

  The invention according to claim 20 is the invention according to any one of claims 1 to 19, wherein the time of the own device is encrypted with the other device even after the time is corrected by the time correction means. When an electronic certificate held for communication expires, a new electronic certificate can be used for encrypted communication using a special electronic certificate that does not check the time of the host device that manages the device. And an electronic certificate issuance request means for requesting the issuance of.

  The invention according to claim 21 is stored in a storage medium accessible by the own apparatus or the own apparatus even after the time is corrected by the time correcting means in the invention according to any one of the first to twentieth aspects. If the time of the file or data is abnormal, the file / data deletion / updating means that deletes or updates the file or data based on the importance of the file or data, or the host system that manages the device itself A third time abnormality notification means for notifying the time abnormality of the file or data is provided.

  The invention according to claim 22 is the special feature in which the time check is not performed on the other device in the invention according to any one of claims 1 to 21 when the expired electronic certificate cannot be renewed. Self-device stop notification means for notifying the stop of the self-device in encrypted communication using an electronic certificate, self-device stop means for stopping the self-device after notifying by the self-device stop notification means, and stopping the self-device. Own device stop notification means for notification.

  A twenty-third aspect of the invention includes the time synchronizer according to any one of the first to twenty-second aspects.

  According to a twenty-fourth aspect of the present invention, when a time synchronization device that measures the time of its own device using an internal clock communicates with another device, the time of the host device that manages the own device is acquired, A time synchronization method that synchronizes the time, the trigger detection step for detecting the trigger for the time correction of the internal clock, and the clock correction for the internal clock when the trigger for the time correction is detected by the trigger detection step And a time correction step of correcting the time of the own device to the time of the host device.

  The invention according to claim 25 is the invention according to claim 24, wherein the trigger detection step compares the time of the host device acquired from the host device with the time of the own device measured by the internal clock, It is determined whether or not the difference is within a predetermined allowable time error range, and when the difference between the two times is not within the allowable time error range as a result of the determination, it is detected as a trigger that requires time correction. Features.

  According to a twenty-sixth aspect of the present invention, in the invention according to the twenty-fourth or twenty-fifth aspect, the trigger detection step requires time correction when storing predetermined information in the storage medium together with the time of the higher-level device acquired from the higher-level device. It is detected as an opportunity.

  According to a twenty-seventh aspect of the present invention, in the invention according to any one of the twenty-fourth to twenty-sixth aspects, the trigger detection step includes an expiration date of an electronic certificate held for the device itself to perform encrypted communication with another device. Is compared with the time of the own device measured by the internal clock to determine whether the time of the own device is within the validity period of the electronic certificate. It is characterized in that a case where the certificate is not within the valid period is detected as an opportunity that requires time correction.

  According to a twenty-eighth aspect of the present invention, in the invention according to any one of the twenty-fourth to twenty-seventh aspects, the trigger detection step is performed when the own apparatus performs encrypted communication with another apparatus using an electronic certificate. Compares the expiration date of the electronic certificate sent from the device with the time of the device itself measured by the internal clock, and determines whether the time of the device is within the validity period of the electronic certificate. As a result of the determination, a case where the time of the own device is not within the validity period of the electronic certificate is detected as an opportunity that requires time correction.

  According to a twenty-ninth aspect of the present invention, in the invention according to any one of the twenty-fourth to twenty-eighth aspects, the trigger detection step includes the step of detecting information sent from a lower-level device during communication with a lower-level device managed by the own device The time of the lower device included in the device is compared with the time of the own device measured by the internal clock, and the time of the lower device is determined. As a result of the determination, the time of the lower device is later than the time of the own device. Or when it is past the predetermined time as a trigger that requires time correction.

  The invention according to claim 30 is the invention according to any one of claims 24 to 29, wherein the trigger detection step includes a time stamp of a packet sent from another device, and an internal Compares the time of the device with the time measured by the clock to determine whether the difference between the two times is within a predetermined allowable time error range. As a result of the determination, the difference between the two times is within the allowable time error range. It is characterized in that a case that is not within is detected as an opportunity that requires time correction.

  According to a thirty-first aspect of the invention, in the invention according to any one of the twenty-fourth to thirty-third aspects, the trigger detection step indicates a time when a notification that the time of the own device is abnormal is received from another device. It is detected as an opportunity that requires correction.

  According to a thirty-second aspect of the invention, in the invention according to any one of the twenty-fourth to thirty-first aspects, the trigger detection step includes a constant period measured by a timer with a monotonically increasing clock that is not affected by the internal clock. It is detected as an opportunity that requires time correction.

  The invention according to claim 33 is the invention according to any one of claims 24 to 32, characterized in that the trigger detection step detects when the own apparatus is activated as a trigger that requires time correction. To do.

  According to a thirty-fourth aspect of the invention, in the invention according to any one of the twenty-fourth to thirty-third aspects, the trigger detection step requires time correction when an operation for changing the time and time zone of the internal clock is received. It is characterized by detecting as a trigger.

  The invention according to claim 35 is the invention according to any one of claims 24 to 34, wherein the trigger detection step includes a time stamp of a file and a directory stored in a storage medium accessible by the own device, Compare with the time of its own device measured by the internal clock, determine the time stamp of the file and directory, and if the result of the determination is that the time stamp of the file and directory is later than the time of its own device, or Detecting a time that needs to be corrected when it is past the predetermined time.

  According to a thirty-sixth aspect of the invention, in the invention according to any one of the twenty-fourth to thirty-fifth aspects, the trigger detection step is measured by a time included in the content of data held by the own device and an internal clock. Compared with the time of the own device, the time included in the content of the data held by the own device is determined, and as a result of the determination, the time included in the content of the data held by the own device is In this case, it is detected that a time that needs to be corrected is detected when the time is later than the time or when it is past the predetermined time.

  The invention according to claim 37 is the invention according to any one of claims 24 to 37, wherein the trigger detection step needs to correct the time when there is an inquiry from a lower device about the time of the own device. And a response step of responding to the time of the own device in response to an inquiry from the lower device after the time of the own device is corrected by the time correction step.

  The invention as set forth in claim 38 is the invention according to any one of claims 24 to 37, wherein, as a result of time correction by the time correction step, the time of the own apparatus is normal, It has the 1st time abnormality notification step which notifies the time abnormality of an apparatus, or the expiration date of the electronic certificate of another apparatus.

  According to a thirty-ninth aspect of the present invention, in the invention according to any one of the twenty-fourth to thirty-eighth aspects, when the time of the internal clock has returned to the default as a result of the time correction by the time correction step, It is characterized by having a second time abnormality notification step for detecting an abnormality of the built-in battery for maintaining the internal clock when it is not, and notifying the host device of that fact to that effect.

  The invention according to claim 40 is the invention according to any one of claims 24 to 39, wherein the time correction step calculates the time required for the reception process during the time inquiry communication with the host device that manages the device. The measurement is performed using a monotonically increasing clock that is not affected by the internal clock, and the time correction is performed after adding the measurement result to the time acquired from the host device as a time lag caused by communication processing.

  The invention according to claim 41 is the invention according to any one of claims 24 to 40, wherein the accuracy of the coarse one of the accuracy of the internal clock and the accuracy of the internal clock of the host device managing its own device is And an allowable time error setting step capable of setting an allowable time error up to ± N (N: a predetermined number) times the minimum number of digits.

  The invention according to claim 42 is the invention according to any one of claims 24 to 41, wherein mutual authentication and encrypted communication using an electronic certificate are performed when the time of the host device is acquired from the host device. It is characterized by having a security step that protects the legitimacy of the time of the host device and prevents the falsification of the time of the host device.

  The invention according to claim 43 is the invention according to any one of claims 24 to 42, wherein the time of the own device is encrypted with the other device even after the time is corrected by the time correction step. When an electronic certificate held for communication expires, a new electronic certificate can be used for encrypted communication using a special electronic certificate that does not check the time of the host device that manages the device. An electronic certificate issuance requesting step for requesting the issuance of an electronic certificate.

  The invention according to claim 44 is stored in a storage medium accessible by the own apparatus or the own apparatus even after the time is corrected by the time correction step in the invention according to any one of claims 24 to 43. If the time of the file or data is abnormal, the file / data deletion / update step that deletes or updates the file or data based on the importance of the file or data, or the host system that manages the device A third time abnormality notification step for notifying the time abnormality of the file or data is provided.

  The invention according to claim 45 is the special feature in which, in the invention according to any one of claims 24 to 44, when the expired electronic certificate cannot be renewed, the time check is not performed on the other device. The self-device stop notification step for notifying the stop of the own device, the self-device stop step for stopping the self-device after notification by the self-device stop notification step, and the stop of the self-device And a self-device stop notification step for notification.

  The invention according to claim 46 allows a time synchronization device that measures the time of its own device using an internal clock to acquire the time of a host device that manages its own device when communicating with the other device, A program to synchronize the time, when the time synchronization device detects the trigger that needs to correct the time of the internal clock, and the trigger that detects the time is detected by the trigger detection process As a time correction of the internal clock, a time correction process for correcting the time of the own device to the time of the host device is executed.

  The invention according to claim 47 is the invention according to claim 46, wherein the trigger detection processing compares the time of the host device acquired from the host device with the time of the own device measured by the internal clock, A process for determining whether or not the difference is within a predetermined allowable time error range, and detecting that the difference between the two times is not within the allowable time error range as a trigger that requires time correction. It is characterized by being.

  According to a 48th aspect of the present invention, in the invention according to the 46th or 47th aspect, the trigger detection process requires time correction when storing predetermined information in the storage medium together with the time of the upper apparatus acquired from the upper apparatus. It is the process detected as an opportunity.

  According to a 49th aspect of the present invention, in the invention according to any one of the 46th to 48th aspects of the present invention, the trigger detection process is performed by the expiration date of an electronic certificate held by the own apparatus for performing encrypted communication with another apparatus. Is compared with the time of the own device measured by the internal clock to determine whether the time of the own device is within the validity period of the electronic certificate. The present invention is characterized in that it is a process for detecting when the certificate is not within the validity period as an opportunity that requires time correction.

  The invention according to claim 50 is the invention according to any one of claims 46 to 49, wherein the trigger detection process is performed when the own apparatus performs encrypted communication with the other apparatus using an electronic certificate. Compares the expiration date of the electronic certificate sent from the device with the time of the device itself measured by the internal clock, and determines whether the time of the device is within the validity period of the electronic certificate. As a result of the determination, the process is characterized in that it detects when the time of its own device is not within the range of the validity period of the electronic certificate as an opportunity that requires time correction.

  The invention according to claim 51 is the invention according to any one of claims 46 to 50, wherein the trigger detection process is information sent from a lower-level device during communication with a lower-level device managed by the own device. The time of the lower device included in the device is compared with the time of the own device measured by the internal clock to determine the time of the lower device, and as a result of the determination, the time of the lower device is greater than the time of the own device. The present invention is characterized in that it is a process of detecting when it is in the future or when it is past a predetermined time as an opportunity that requires time correction.

  The invention according to claim 52 is the invention according to any one of claims 46 to 51, wherein the trigger detection processing includes a time stamp of a packet sent from another device, and an internal Compares the time of the device with the time measured by the clock to determine whether the difference between the two times is within a predetermined allowable time error range. As a result of the determination, the difference between the two times is within the allowable time error range. It is the process which detects the case which is not in the inside as an opportunity which needs time correction.

  The invention according to claim 53 is the invention according to any one of claims 46 to 52, in which the trigger detection process is performed when the notification that the time of the own apparatus is abnormal is received from another apparatus. It is the process which detects as an opportunity which needs correction | amendment.

  According to a 54th aspect of the present invention, in the invention according to any one of the 46th to 53rd aspects, the trigger detection process is performed at regular intervals measured by a timer with a monotonically increasing clock that is not affected by the internal clock. It is the process which detects as an opportunity which needs time correction.

  According to a 55th aspect of the present invention, in the invention according to any one of the 46th to 54th aspects, the trigger detection process is a process of detecting when the own apparatus is activated as a trigger that requires time correction. It is characterized by.

  According to a 56th aspect of the present invention, in the invention according to any one of the 46th to 55th aspects, the trigger detection process requires time correction when an operation to change the time and time zone of the internal clock is received. It is the process which detects as a special opportunity.

  The invention according to claim 57 is the invention according to any one of claims 46 to 56, wherein the trigger detection process includes a time stamp of a file and a directory stored in a storage medium accessible by the own device, Compare with the time of its own device measured by the internal clock, determine the time stamp of the file and directory, and if the result of the determination is that the time stamp of the file and directory is later than the time of its own device, or The process is characterized in that it is a process of detecting a time that needs to be corrected when it is past the predetermined time.

  The invention according to claim 58 is the invention according to any one of claims 46 to 57, wherein the trigger detection process is measured by the time included in the content of the data held by the own device and an internal clock. Compared with the time of the own device, the time included in the content of the data held by the own device is determined, and as a result of the determination, the time included in the content of the data held by the own device is This process is characterized in that it is a process that detects a time that needs to be corrected when the time is later than the time or the time that is past the predetermined time.

  The invention according to claim 59 is the invention according to any one of claims 46 to 59, wherein the trigger detection processing requires time correction when there is an inquiry from a lower device about the time of the own device. It is a detection process as an opportunity, and after the time of the own apparatus is corrected by the time correction process, the time synchronization apparatus is allowed to execute a response process that responds to the time of the own apparatus in response to an inquiry from a lower apparatus. Features.

  The invention according to claim 60 is the invention according to any one of claims 46 to 59, wherein, as a result of time correction by the time correction processing, if the time of the own apparatus is normal, the time synchronization apparatus is On the other hand, the first time abnormality notification process for notifying the time abnormality of the other device or the expiration date of the electronic certificate of the other device is executed.

  In the invention of claim 61, in the invention of any one of claims 46 to 60, when the time of the internal clock is returned to the default as a result of the time correction by the time correction process, Detecting an abnormality of the internal battery for maintaining the internal clock when the power of the own device is not turned on, and executing a second time abnormality notification process for notifying the upper device managing the own device to that effect Features.

  The invention according to claim 62 is the invention according to any one of claims 46 to 61, wherein the time correction processing is performed by calculating a time required for reception processing during time inquiry communication with a host device that manages the device. This is characterized in that the measurement is performed using a monotonically increasing clock that is not affected by the internal clock, and the measurement result is added to the time acquired from the host device as the time lag caused by the communication process, and then the time is corrected.

  According to a 63rd aspect of the present invention, in the invention according to any one of the 47th to 62nd aspects, the time synchronizer includes: the accuracy of the internal clock; and the accuracy of the internal clock of the host device that manages the own device. An allowable time error setting process capable of setting up to ± N (N: a predetermined number) times the minimum number of digits of the coarser accuracy as an allowable time error is executed.

  The invention according to claim 64 is the invention according to any one of claims 46 to 63, wherein the time synchronizer uses the electronic certificate to obtain the time of the host device from the host device. In addition, the use of encrypted communication protects the legitimacy of the time of the host device and executes security processing for preventing falsification of the time of the host device.

  The invention according to claim 65 is the invention according to any one of claims 46 to 64, wherein the time of the own device is encrypted with the other device even after the time is corrected by the time correction processing. When the digital certificate held for communication expires, the time synchronization device is encrypted communication with a special electronic certificate that does not check the time with the host device that manages the device itself. The electronic certificate issuance request process for requesting the issuance of a new electronic certificate is executed.

  According to a 66th aspect of the present invention, in the invention according to any one of the 46th to 65th aspects, even after the time is corrected by the time correction process, the self apparatus is stored in an accessible storage medium or the self apparatus. If the time of the file or data is abnormal, the time synchronization device deletes or updates the file or data based on the importance of the file or data, or the device itself A third time abnormality notification process for notifying a time abnormality of a file or data to a higher system to be managed is executed.

  The invention according to claim 67 is the invention according to any one of claims 46 to 66, wherein when the expired electronic certificate cannot be renewed, the time synchronizer is checked against other devices. A self-device stop notification process for notifying the stop of the self-device in encrypted communication using a special electronic certificate that is not performed, and a self-device stop process for stopping the self-device after notifying by the self-device stop notification processing, And a self-device stop notification process for notifying the stop of the self-device.

  According to the present invention, it is possible to perform time correction at a more accurate and optimal timing.

  The best mode for carrying out the present invention will be described below in detail with reference to the accompanying drawings.

As an embodiment of the present invention, a configuration of a time synchronization system (communication system) is shown in FIG.
As shown in FIG. 1, the time synchronization system of this embodiment includes an installation environment A and an installation environment B. In the installation environment A, the G / W device 1 (high-order device) that is a management device and the mediation that is a managed device that is connected to the G / W device 1 via the Internet 4 and is managed by the G / W device 1. Device 2 (lower device of G / W device 1 and higher device for image printing device 3), and image printing device 3 connected to this mediation device 2 via a LAN or the like (lower level of mediation device 2) Device). In the installation environment B, an image that is a managed device that is connected to the G / W device 1 (high-level device), which is a management device, and the G / W device 1 via the Internet 4 and is managed by the G / W device 1. Printing device 5 (subordinate device of G / W device 1). In the installation environment A, the intermediary device 2 and the image printing device 5 in the installation environment B are time synchronization devices of the present embodiment, respectively.

FIG. 2 shows a functional configuration of the time synchronization device (the mediation device 2 and the image printing device 5) of the present embodiment.
As shown in FIG. 2, the time synchronization apparatus of the present embodiment indicates the own apparatus (the time synchronization apparatus itself. The other apparatus is an apparatus that communicates with the time synchronization apparatus, and indicates an upper apparatus and a lower apparatus. ) Has an internal clock 11 that measures the current time (current date and time). In addition, it has a built-in battery 10 for maintaining the operation of the internal clock 11 when the apparatus is not turned on.

  As shown in FIG. 2, the time synchronizer according to the present embodiment has a monotonically increasing clock 17 for measuring the time without being affected by the device starting means 14 and the internal clock 11 for starting the own device, and measuring the monotonically increasing clock. Based on the result, it has a scheduler 15 that executes a preset schedule (for example, communication with other devices).

  As shown in FIG. 2, the time synchronization apparatus of the present embodiment includes a higher-level device communication unit 23 for communicating with a higher-level device and a lower-level device communication unit 25 for communicating with a lower-level device. Further, the electronic certificate for higher-level device communication 24 for use in communication with the higher-level device and the lower-level device communication electronic certificate 27 for use in communication with the lower level device are held. In these cases, when the host device time acquisition means 16 acquires the host device time from the host device, the authenticity of the host device time is protected by using mutual authentication and encrypted communication using an electronic certificate. At the same time, it functions as a security means for preventing falsification of the time of the host device. Therefore, since the legitimacy of the time information of the host device that is the basis of the time correction is maintained, it is possible to prevent falsification of the time information and spoofing of the host device. In addition, the time synchronization apparatus of the present embodiment includes an electronic certificate update unit 18 that updates these electronic certificates.

  As shown in FIG. 2, the time synchronization apparatus of the present embodiment has time information (hereinafter simply referred to as “time”) indicating the current time (current date and time) of the host device, measured by an internal clock of the host device. The high-order apparatus time acquisition means 16 is acquired.

  As shown in FIG. 2, the time synchronization apparatus of the present embodiment includes an input operation receiving unit 19 (time changing unit) that receives an input operation from a user and sets / changes the time and time zone of the internal clock 11. Further, the input operation accepting means 19 has a minimum accuracy of ± N (N: a predetermined number) of the accuracy of the internal clock 11 and the accuracy of the internal clock of the host device that manages the device itself. It is also possible to accept an input operation for setting up to twice as an allowable time error (allowable time error setting means). Therefore, since an allowable error range can be specified, the balance between the time correction frequency and the time accuracy can be adjusted.

  As shown in FIG. 2, the time synchronization apparatus according to the present embodiment is accessible by the own apparatus and includes a storage medium 20 for storing predetermined information (data, file, directory).

  As illustrated in FIG. 2, the time synchronization apparatus according to the present embodiment includes a comparison target time acquisition unit 21 that acquires a comparison target time. The comparison target time is time information to be compared with the time of the internal clock 11 by the time comparison unit 13 described later. As an example, the time input by the input operation means 19, the time included in the information stored in the storage medium 20, the expiration date of the electronic certificate 24 for upper device communication and 27 for lower device communication, received from another device Time (for example, time stamp of a packet, etc.), etc. are mentioned.

  As shown in FIG. 2, the time synchronization apparatus according to the present embodiment compares the time of the own apparatus measured by the internal clock 11 with the time of the upper apparatus acquired by the upper apparatus time acquisition means 16. 13 The time comparison unit 13 compares the time of the own device measured by the internal clock 11 with the predetermined comparison target time acquired by the comparison target time acquisition unit 21. In addition to the time comparison function for comparing the times as described above, the time comparison unit 13 also has a function of detecting a trigger (timing) that requires time correction (time synchronization) of the internal clock 11. That is, an opportunity that requires time correction of the internal clock 11 is detected based on the result of comparing the times and the event (processing) in the own device. In the present embodiment, the time comparison means 13 has an opportunity detection function, but may be provided separately. Details of this opportunity detection function will be described later.

  As shown in FIG. 2, the time synchronization apparatus according to the present embodiment displays the time of its own device measured by the internal clock 11 when the time comparison unit 13 detects a trigger that requires time correction. Time correction means 12 for correcting to the time of the host device acquired by the time acquisition means 16 is provided. The time correction means 12 measures the time required for the reception process during the time inquiry communication with the host device that manages the own device using the monotonically increasing clock 17 that is not affected by the internal clock, and the result of this measurement is obtained. As a time lag caused by the communication processing, time correction may be performed after adding to the time acquired from the host device. Thus, the time can be corrected more accurately by adding the time lag required for communication for acquiring the time of the host device.

  As shown in FIG. 2, the time synchronization apparatus of the present embodiment includes time abnormality notification means 22. The time abnormality notifying means 22 indicates that the time of the own apparatus is normal to the other apparatus when the time of the own apparatus is normal as a result of the time correction by the time correcting means 12 (or the other apparatus That the electronic certificate of the other device has expired (first time abnormality notification means). Therefore, by detecting and notifying that the time of the other device is abnormal or that the expiration date of the electronic certificate of the other device has expired, it is possible to inform the other device of the timing of time correction and certificate update, Further, by detecting and notifying that the clock of the other device is abnormal, it is possible to inform the other device of the timing for time correction.

  In addition, when the time of the internal clock 11 returns to the default as a result of the time correction by the time correction unit 12, the time abnormality notification unit 22 detects that the internal battery 10 is abnormal, and manages the device accordingly. (Second time abnormality notification means). Therefore, by detecting that the time of the device itself cannot be maintained, it is possible to detect an abnormality of the internal battery without a module for checking the remaining amount of the internal battery.

  In addition, the time abnormality notifying means 22 is used even when the time of the file or data stored in the storage device accessible by the own apparatus or the own apparatus is abnormal even after the time correction by the time correcting means 12. Then, the time abnormality of the file or data is notified to the host system that manages the own device (third time abnormality notification means). If the time of the file or data is abnormal, file / data deletion / update means (not shown) for deleting or updating the file or data is provided based on the importance of the file or data. May be. In this way, it is possible to maintain the correctness of files and data by detecting files and data that have already been created at the wrong time and responding according to the importance of each file.

  In addition, the time abnormality notifying unit 22 has the time of its own device after the time correction unit 12 corrects the time, and the electronic certificate held by the own device for performing encrypted communication with another device has expired. If this is the case, a function that requests the higher-level device that manages the device itself to issue a new electronic certificate by encrypted communication using a special electronic certificate (rescue certificate 26) that is not time-checked (rescue certificate 26). Electronic certificate issuing request means). Thus, by checking the validity period of the electronic certificate from the corrected result, it is possible to prevent the electronic certificate that has not expired from being updated. Further, it is possible to prevent interception of new electronic certificate issuance by encrypted communication.

  Further, the time abnormality notifying means 22 also has a function (response means) for responding to inquiries from lower devices managed by the own device, and after the time of the own device is corrected by the time correcting means 12, In response to an inquiry from a lower-level device, the time of its own device is returned. Therefore, it is possible to make the time transmitted to the lower device accurate.

  As shown in FIG. 2, the time synchronization apparatus according to the present embodiment is a special electronic certificate (rescue certificate) that is not time-checked to other apparatuses when an expired electronic certificate cannot be updated. 26) It has own device stop means 28 for notifying the stop of the own device by the encrypted communication according to 26) and stopping the own device after the notification. Further, as means for notifying the stop of the own apparatus (own apparatus stop notifying means), there are a stop screen display means 29 for displaying a message indicating that the own apparatus is stopped, and a stop LED lighting means 30 for turning on the LED. Therefore, in the case where it is not possible to operate normally even if the time of the own device is corrected correctly, notification to other devices related to the own device and display of stoppage by LED or screen in the own device By performing the above, it is possible to notify the surroundings and the user that the device is inoperable.

  As described above, the time synchronization apparatus according to the present embodiment is a time synchronization apparatus having a function of synchronizing time with another apparatus when communicating with another apparatus (higher-order apparatus or lower-order apparatus). Internal clock 11 that measures the time of its own device (time synchronization device itself), upper device time acquisition means 16 that acquires the time of the higher-level device that manages its own device, and triggers that require time correction of internal clock 11 are detected When the time comparison means 13 having an opportunity detection function and the opportunity detection function of the time comparison means 13 detect an opportunity that requires time correction, the time of the own device is set as the time of the host device as time correction of the internal clock 11. And a time correction means for correcting to a main structure.

  Here, “the trigger detection function of the time comparison unit 13”, which is a main feature of the present time synchronization apparatus, will be described in detail. As described above, the trigger detection function is a function that detects a trigger (timing) that requires time correction (time synchronization) of the internal clock 11. When the predetermined trigger described below is detected by this function, the time of the own device measured by the internal clock 11 is acquired by the host device time acquisition unit 16 by the time correction unit 12. It is corrected (synchronized) with the time of the host device.

  As a detection example 1, the time comparison function compares the time of the host device acquired by the host device time acquisition means 16 with the time of its own device measured by the internal clock 11, and the trigger detection function It is determined whether or not the difference is within a predetermined allowable time error range, and if the result of the determination is that the difference between the two times is not within the allowable time error range, it is detected as a trigger that requires time correction.

  Therefore, according to the detection example 1, since the time of the host device is synchronized when time correction is necessary, the time of the device can be kept correct.

  As a detection example 2, the trigger detection function uses a time at which time correction is required as a time when predetermined information (such as important information) is stored in the storage medium 20 together with the time of the host device acquired by the host device time acquisition unit 16. Detect.

  Therefore, according to the detection example 2, it is possible to ensure that the time of information stored in the storage medium 20 is correct.

  As a detection example 3, the time comparison function compares the expiration date of the electronic certificate held by the own device for performing encrypted communication with another device and the time of the own device measured by the internal clock, and detects the trigger. The function determines whether or not the time of its own device is within the validity period of the electronic certificate, and if the result of the determination is that the time of its own device is not within the validity period of the electronic certificate, Detected as an opportunity for correction.

  Therefore, according to the detection example 3, since the time when the current time of the own device is outside the range of the validity period of the electronic certificate is necessary as the time correction, the time when the own device is outside the validity period of the electronic certificate. Can be prevented from moving in.

  As detection example 4, the time comparison function is measured by the expiration date of the electronic certificate sent from the other device and the internal clock when the device performs encrypted communication with the other device using the electronic certificate. The trigger detection function compares the time of its own device and determines whether the time of its own device is within the validity period of the electronic certificate. When it is not within the range of the expiration date, it is detected as an opportunity that requires time correction.

  Therefore, according to the detection example 4, since the time when the current time of the own device is out of the validity period of the electronic certificate sent from the other device is an opportunity that requires time correction, the electronic certificate of the other device is used. Can guarantee and reject the certificate correctly.

  As a detection example 5, the time comparison function uses the time of the lower device included in the information sent from the lower device and the own device measured by the internal clock when communicating with the lower device managed by the own device. The trigger detection function determines the time of the lower device, and if the result of the determination is that the time of the lower device is later than the time of the own device, or is past the predetermined time Is detected as an opportunity that requires time correction.

  Therefore, according to the detection example 5, the result of comparing the current time of the own device and the time of the other device included in the information transmitted from the other device is used as a trigger for time correction. An abnormality in the time of another device can be detected.

  As a detection example 6, the time comparison function compares the time stamp of the packet sent from the other device with the time of the own device measured by the internal clock at the time of communication with the other device. It is determined whether the difference between the two times is within the range of the allowable time error, and if the result of the determination is that the difference between the two times is not within the range of the allowable time error, it is detected as a trigger that requires time correction. To do.

  Therefore, according to the detection example 6, since the result of comparing the current time of the own device and the time stamp of the communication packet with the other device is an opportunity for time correction, the detection examples 4 and 5 It is possible to detect an abnormality in the time of the own device or other device during communication that cannot be performed.

  As a detection example 7, the trigger detection function detects when a notification that the time of its own device is abnormal is received from another device as a trigger that requires time correction.

  Therefore, according to the detection example 7, the reception of the notification of the time abnormality from the other device is used as a trigger for the time correction, so that the time abnormality that cannot be detected by the device itself can be detected.

  As a detection example 8, the trigger detection function detects a fixed period measured by a timer with a monotonically increasing clock as a trigger that requires time correction.

  Therefore, according to the detection example 8, since there is an opportunity for periodic time correction that is not affected by the clock held by the apparatus, the time is periodically corrected, and a schedule based on the clock (for example, another apparatus) Communication) is not executed due to clock rewinding or the like (detection examples 4, 5, 6, etc.), there is a possibility that time adjustment will not occur indefinitely, but this can be covered.

  As detection example 9, the trigger detection function detects when the own apparatus is started as a trigger that requires time correction.

  Therefore, according to the detection example 9, when the power is turned off, the time information of the clock is maintained, the battery is dead, and the time is returned to the default, or when the power is originally turned off. When the time information is not held, the time of startup is used as a trigger for time correction, so that the time in the above case can be corrected correctly.

  As detection example 10, the trigger detection function detects when an operation for setting and changing the time and time zone of the internal clock is received by the input operation reception unit 19 as a trigger that requires time correction.

  Therefore, according to the tenth detection example, when the information related to the time of the internal clock 11 is changed by an input operation from the screen or the like, the time correction is used as an opportunity to correct the time. Can do.

  According to the detection example 11, the time comparison function compares the time stamp of the file and directory stored in the storage medium accessible to the own device with the time of the own device measured by the internal clock, and detects the trigger. The function determines the time stamp of the file and directory. As a result of the determination, if the time stamp of the file and directory is later than the time of its own device, or if it is past the predetermined time. Detected as an opportunity that requires time correction.

  Therefore, according to the detection example 11, since the time abnormality is detected from the result of comparing the current time of the own device and the time stamp of the file of the storage medium 20 and the time correction is triggered, each time the file is accessed Time information can be corrected.

  As a detection example 12, the time comparison function compares the time included in the content of data held by the own device with the time of the own device measured by the internal clock, and the trigger detection function is held by the own device. If the time included in the data content held by the own device is later than the time of the own device as a result of the determination, or a predetermined time A case where the time is earlier than the time is detected as an opportunity that requires time correction.

  Therefore, according to the detection example 12, the abnormality is detected from the comparison between the current time of the own device and the time in the data file held in the own device, and the time correction is triggered. The time can be corrected for each access.

  As a detection example 13, the trigger detection function detects when an inquiry from a lower-level device is received for the time of the own device as a trigger that requires time correction.

  Therefore, according to the detection example 13, when the time information is inquired from the lower device, the time correction is triggered, so the time information transmitted to the lower device can be made accurate.

  Each means and each function described above may be realized by either hardware or software. When implemented by software, a time synchronization program is read into the time synchronization apparatus of the present embodiment and controls the operation of the time synchronization apparatus. The time synchronization apparatus realizes the above-described means and functions by the control of the time synchronization program, and executes processing operations described below.

  Next, the basic processing operation of the time synchronization apparatus of this embodiment will be described with reference to FIG. In FIG. 4, acquisition of time information from the host device, correction of the time of the own device, and update of the electronic certificate will be described.

  Encrypted communication using the electronic certificate is performed on the host device (G / W device 1 in FIG. 1) (step S1 / YES), and it is determined whether the encrypted communication is successful (step S2).

  In step S2, when the encrypted communication is successful (step S2 / success), time information indicating the time of the host device measured by the internal clock of the host device is acquired from the host device (step S3). Then, the time measured by the internal clock 11 of the time synchronizer is compared with the time information acquired from the host device (step S4), and whether or not the difference between the two times is within a preset allowable range. Judgment is made (step S5). Here, if the difference is within the allowable range (step S5 / within range), the process proceeds to B without correcting the time of the internal clock 11 (see FIG. 3 for processing after B). If the difference is outside the permissible range (step S5 / out of range), as described in the detection example 1 above, this is detected as a trigger for time correction, and the time of the internal clock 11 is corrected to the time of the upper clock ( Step S6), proceed to C (see FIG. 3 for processing after C).

  If the encrypted communication fails in step S2 (step S2 / failure), it is determined whether or not the HTTP has failed (step S8). Here, when it is a failure of HTTP (step S8 / YES), it returns to step S1 and tries again. If the HTTP is successful (step S8 / NO), it is determined whether or not the electronic certificate (the upper apparatus communication electronic certificate 24 in FIG. 1) has expired (step S9).

  In step S9, if the validity period of the electronic certificate has not expired (step S9 / NO), it is determined whether or not it is worth retrying (step S10). If it is worth retrying (step S10 / YES), the process returns to step S1 to retry. If there is no value for retry (step S10 / NO), the process proceeds to D (see FIG. 3 for the process after D).

  In step S9, when the validity period of the electronic certificate has expired (step S9 / YES), the electronic certificate stored in the own device is deleted (step S11). Communication with the host device is performed using a “digital certificate with no expiration date” different from the deleted electronic certificate (step S12), and it is determined whether the communication is successful (step S13).

  If communication fails in step S13 (step S13 / failure), it is determined whether or not there is a retry value (step S14). If it is worth retrying (step S14 / YES), the process returns to step S12 to retry. If there is no value for retry (step S14 / NO), the process proceeds to D (see FIG. 3 for the process after D).

  In step S13, when communication is successful (step S13 / success), time information indicating the time of the host device measured by the host device's internal clock is acquired from the host device and measured by the internal clock 11 of the time synchronization device. The time thus obtained is compared with the time information acquired from the host device (step S15), and it is determined whether or not the difference between the two times is within a preset allowable range (step S16). Here, if the difference is within the allowable range (step S16 / within range), the host device is requested to issue a new electronic certificate (step S18). If the difference is outside the allowable range (step S16 / out of range), as described in the detection example 1 above, this is detected as a trigger for time correction, and the time of the internal clock 11 is corrected to the time of the upper clock ( In step S17), a higher-level device is requested to issue a new electronic certificate (step S18).

  Then, it is determined whether or not the host device has issued a new electronic certificate (step S19). When a new electronic certificate is not issued (step S19 / NO), the process proceeds to F (see FIG. 3 for the process after F). When a new electronic certificate is issued (step S19 / YES), the electronic certificate is updated to a newly issued one (step S20), and the process proceeds to E (see FIG. 3 for the processing after E).

  Next, the timing of time correction and the processing after time correction in the time synchronization apparatus of the present embodiment will be described with reference to the flows of FIGS.

  FIG. 3A shows a case where the time synchronization device is activated (detection example 9) as a trigger for time correction. In this case, after the time correction is detected, the flow of FIG. And when it comes to BE of FIG. 4, a normal operation | movement is started. When the process reaches F in FIG. 4, the other apparatus is notified of the stop of the own apparatus, and the own apparatus is stopped.

  FIG. 3B shows a case where a time correction is detected when a time abnormality such as a file is detected (detection examples 11 and 12). In this case, after the time correction is detected, the flow of FIG. When the process reaches B in FIG. 4, deletion / change / notification to other apparatuses is performed according to the importance of the file. When reaching C to E in FIG. 4, the normal operation is continued. When the process reaches F in FIG. 4, the other apparatus is notified of the stop of the own apparatus, and the own apparatus is stopped.

  FIG. 3C shows the timing of time correction when a time abnormality notification is received from another device (detection example 7) and when a time abnormality is detected during communication with another device (detection examples 5 and 6). This is the case. In these cases, after detecting the timing of time correction, the flow of FIG. When the process reaches B in FIG. 4, the abnormality of the other apparatus is detected and the time abnormality is notified to the other apparatus. When reaching C to E in FIG. 4, the normal operation is continued. When the process reaches F in FIG. 4, the other apparatus is notified of the stop of the own apparatus, and the own apparatus is stopped.

  FIG. 3A shows a periodical (detection example 8), a predetermined information storage (detection example 2), an electronic certificate expiration date check (detection examples 3 and 4), an input operation accepting means (input screen). And so on) (detection example 10), and when there is a time inquiry from a lower-level device (detection example 13). In these cases, after detecting the timing of time correction, the flow of FIG. And when it comes to BE of FIG. 4, normal operation | movement is continued. When the process reaches F in FIG. 4, the other apparatus is notified of the stop of the own apparatus, and the own apparatus is stopped.

  As mentioned above, although embodiment of this invention was described, it is not limited to the said embodiment, A various deformation | transformation is possible in the range which does not deviate from the summary.

It is a figure which shows the structural example of the time synchronizer of this invention, and another apparatus (high-order apparatus and low-order apparatus). It is a block diagram which shows the function structure of the time synchronizer of this invention. It is a flowchart which shows the basic operation | movement of the time synchronizer of this invention. It is a flowchart which shows the opportunity of time correction in the time synchronization apparatus of this invention, and the operation | movement after time correction, respectively.

Explanation of symbols

1 G / W device (host device)
2 Mediation device (time synchronization device)
3 Image printing equipment (lower device)
4 Internet 5 Image printing equipment (time synchronization device)
DESCRIPTION OF SYMBOLS 10 Built-in battery 11 Internal clock 12 Time correction means 13 Time comparison means 14 Apparatus start-up means 15 Scheduler 16 High-order apparatus time acquisition means 17 Monotonically increasing clock 18 Electronic certificate update means 19 Input operation reception means 20 Storage medium 21 Comparison target time acquisition means 22 Time Abnormal Notification Unit 23 Host Device Communication Unit 24 Host Device Communication Electronic Certificate 25 Subordinate Device Communication Unit 26 Rescue Certificate 27 Subordinate Device Communication Electronic Certificate 28 Own Device Stop Unit 29 Stop Screen Display Unit 30 Stop LED Lighting Unit

Claims (67)

A time synchronization device having a function of synchronizing time with another device when communicating with the other device,
An internal clock that measures the time of its own device,
Host device time acquisition means for acquiring the time of the host device that manages the host device;
Trigger detection means for detecting a trigger that requires time correction of the internal clock;
When the trigger that detects the time correction is detected by the trigger detection unit, the time correction unit that corrects the time of the own device to the time of the host device as the time correction of the internal clock;
A time synchronizer characterized by comprising: The opportunity detection means includes
The time of the host device acquired by the host device time acquisition means is compared with the time of the host device measured by the internal clock, and the difference between the two times is within a predetermined allowable time error range. Determine whether or not
2. The time synchronization apparatus according to claim 1, wherein, as a result of the determination, a case where the difference between the two times is not within the range of the allowable time error is detected as an opportunity that requires the time correction. The opportunity detection means includes
The time when the predetermined information is stored in a storage medium together with the time of the host device acquired by the host device time acquisition unit is detected as an opportunity for the time correction. Time synchronizer. The opportunity detection means includes
The self device compares the expiration date of the electronic certificate held for performing encrypted communication with the other device and the time of the self device measured by the internal clock, and the time of the self device is the electronic device. Determine if it is within the validity period of the certificate,
4. The apparatus according to claim 1, wherein, as a result of the determination, a case where the time of the own device is not within a range of an expiration date of the electronic certificate is detected as an opportunity for the time correction. 5. The time synchronization device according to item. The opportunity detection means includes
When the device itself performs encrypted communication with the other device using the electronic certificate, the expiration date of the electronic certificate sent from the other device, and the time of the device measured by the internal clock To determine whether the time of the device is within the validity period of the electronic certificate,
5. The apparatus according to claim 1, wherein, as a result of the determination, a case where the time of the own device is not within a range of an expiration date of the electronic certificate is detected as an opportunity for the time correction. The time synchronization device according to item. The opportunity detection means includes
When communicating with a lower device managed by the own device, the time of the lower device included in the information sent from the lower device is compared with the time of the own device measured by the internal clock. , Determine the time of the subordinate device,
As a result of the determination, a case where the time of the lower-order device is later than the time of the own device or a time earlier than a predetermined time is detected as an opportunity for the time correction. The time synchronizer according to claim 1, wherein: The opportunity detection means includes
When communicating with the other device, the time stamp of the packet sent from the other device is compared with the time of the own device measured by the internal clock, and the difference between the two times is a predetermined allowable time error. Determine whether it is within range,
7. The method according to claim 1, wherein, as a result of the determination, a case where the difference between the two times is not within the range of the allowable time error is detected as an opportunity that requires the time correction. 8. Time synchronizer. The opportunity detection means includes
8. The time according to claim 1, wherein a time when the time correction is necessary is detected when a notification that the time of the own device is abnormal is received from the other device. 9. Time synchronizer. Having a timer with a monotonically increasing clock not affected by the internal clock;
The opportunity detection means includes
9. The time synchronization apparatus according to claim 1, wherein each time period measured by a timer based on the monotonically increasing clock is detected as an opportunity that requires time correction. 9. The opportunity detection means includes
The time synchronization apparatus according to any one of claims 1 to 9, wherein a time when the own apparatus is activated is detected as a trigger that requires the time correction. Having a time changing means for accepting a predetermined operation and changing the time of the internal clock;
The opportunity detection means includes
11. The time when the time changing means receives an operation for changing the time and time zone of the internal clock as an opportunity that requires the time correction. The time synchronizer described in 1. The opportunity detection means includes
The time stamp of the file and the directory stored in the storage medium accessible to the device is compared with the time of the device measured by the internal clock to determine the time stamp of the file and the directory. ,
As a result of the determination, if the time stamp of the file and the directory is later than the time of the own device, or if it is past the predetermined time, the time correction is necessary. The time synchronization apparatus according to claim 1, wherein the time synchronization apparatus detects the time synchronization apparatus. The opportunity detection means includes
The time included in the content of data held by the own device is compared with the time of the own device measured by the internal clock, and the time contained in the content of data held by the own device is determined. Judgment
As a result of the determination, when the time included in the content of the data held by the own device is later than the time of the own device, or when the time is past the predetermined time, The time synchronization apparatus according to any one of claims 1 to 12, wherein the time synchronization apparatus is detected as an opportunity that requires time correction. Response means for responding to an inquiry from a lower-level device managed by the device;
The opportunity detection means includes
The time when there is an inquiry from the lower device about the time of the own device is detected as an opportunity for the time correction,
The response means includes
14. The time according to any one of claims 1 to 13, wherein the time of the device itself is responded to an inquiry from the lower device after the time of the device itself is corrected by the time correction means. The time synchronizer described. As a result of time correction by the time correction means, when the time of the own device is normal,
15. The apparatus according to claim 1, further comprising a first time abnormality notification unit that notifies the other device of a time abnormality of the other device or an expiration date of the electronic certificate of the other device. The time synchronizer of Claim 1. As a result of time correction by the time correction means, when the time of the internal clock has returned to the default,
A second time abnormality notification means for detecting an abnormality of the internal battery for maintaining the internal clock when the power of the own device is not turned on and notifying the host device managing the own device to that effect The time synchronizer according to claim 1, wherein the time synchronizer is configured as described above. The time correction means includes
The time required for reception processing during time inquiry communication to the host device that manages the device itself is measured using a monotonically increasing clock that is not affected by the internal clock, and the measurement result is used as a time lag caused by communication processing. The time synchronization apparatus according to any one of claims 1 to 16, wherein the time correction is performed after being added to the time acquired from the host apparatus.   Of the accuracy of the internal clock and the accuracy of the internal clock of the host device that manages the device, up to ± N (N: a predetermined number) times the minimum digit of the coarser accuracy is used as the allowable time error. 18. The time synchronization apparatus according to claim 2, further comprising an allowable time error setting means that can be set.   When the time of the host device is acquired from the host device by the host device time acquisition means, the validity of the time of the host device is protected by using mutual authentication and encrypted communication using an electronic certificate. The time synchronization apparatus according to claim 1, further comprising security means for preventing the time of the upper apparatus from being falsified. Even after the time correction by the time correction means, the time of the own device falls under the expiration of an electronic certificate held by the own device for performing encrypted communication with the other device,
It has electronic certificate issuance request means for requesting the issuance of a new electronic certificate by encrypted communication using a special electronic certificate that is not time-checked to the host device that manages the device. The time synchronizer according to any one of claims 1 to 19. After the time correction by the time correction means, if the time of the file or data stored in the storage medium accessible to the own device or the own device is abnormal,
Based on the importance of the file or the data, a file / data deletion / updating unit for deleting or updating the file or the data, or the time of the file or the data to the host system managing the device 21. The time synchronization apparatus according to claim 1, further comprising third time abnormality notification means for notifying abnormality. If you are unable to renew an expired digital certificate,
Self-device stop notification means for notifying the stop of the self-device in encrypted communication using a special electronic certificate that is not time-checked to the other device;
After notifying by the own apparatus stop notification means, the own apparatus stopping means for stopping the own apparatus;
Own device stop notification means for notifying the stop of the own device;
The time synchronizer according to any one of claims 1 to 21, wherein the time synchronizer is provided.   23. A time synchronization system comprising the time synchronization apparatus according to claim 1. When a time synchronization device that measures the time of its own device using an internal clock communicates with another device, it acquires the time of the host device that manages the device and synchronizes the time with the other device. A synchronization method,
Trigger detection step of detecting a trigger that requires time correction of the internal clock;
A time correction step of correcting the time of the own device to the time of the host device, as the time correction of the internal clock, when the trigger that requires the time correction is detected by the trigger detection step;
A time synchronization method characterized by comprising: The opportunity detection step includes
The time of the host device acquired from the host device is compared with the time of the host device measured by the internal clock, and it is determined whether or not the difference between both times is within a predetermined allowable time error range. And
25. The time synchronization method according to claim 24, wherein when the difference between the two times is not within the range of the allowable time error as a result of the determination, the time synchronization method is detected as an opportunity for the time correction. The opportunity detection step includes
26. The time synchronization method according to claim 24, wherein the time when the predetermined information is stored in a storage medium together with the time of the host device acquired from the host device is detected as an opportunity for the time correction. The opportunity detection step includes
The self device compares the expiration date of the electronic certificate held for performing encrypted communication with the other device and the time of the self device measured by the internal clock, and the time of the self device is the electronic device. Determine if it is within the validity period of the certificate,
27. Any one of claims 24 to 26, wherein, as a result of the determination, a case where the time of the self-apparatus is not within the validity period of the electronic certificate is detected as an opportunity for the time correction. The time synchronization method according to item. The opportunity detection step includes
When the device itself performs encrypted communication with the other device using the electronic certificate, the expiration date of the electronic certificate sent from the other device, and the time of the device measured by the internal clock To determine whether the time of the device is within the validity period of the electronic certificate,
28. The method according to claim 24, wherein when the time of the device is not within the validity period of the electronic certificate as a result of the determination, the time is detected as an opportunity for the time correction. The time synchronization method according to item. The opportunity detection step includes
When communicating with the lower device managed by the own device, the time of the lower device included in the information sent from the lower device is compared with the time of the own device measured by the internal clock, Determining the time of the subordinate device;
As a result of the determination, a case where the time of the lower-order device is later than the time of the own device or a time earlier than a predetermined time is detected as an opportunity for the time correction. The time synchronization method according to any one of claims 24 to 28, wherein: The opportunity detection step includes
When communicating with the other device, the time stamp of the packet sent from the other device is compared with the time of the own device measured by the internal clock, and the difference between the two times is a predetermined allowable time error. Determine whether it is within range,
30. The method according to any one of claims 24 to 29, wherein, as a result of the determination, a case where the difference between the two times is not within the range of the allowable time error is detected as an opportunity that requires the time correction. Time synchronization method. The opportunity detection step includes
31. The time according to any one of claims 24 to 30, wherein a time when the time correction is necessary is detected when a notification that the time of the own device is abnormal is received from the other device. Time synchronization method. The opportunity detection step includes
32. The apparatus according to claim 24, wherein a predetermined period measured by a timer using a monotonically increasing clock that is not affected by the internal clock is detected as an opportunity that requires time correction. Time synchronization method. The opportunity detection step includes
The time synchronization method according to any one of claims 24 to 32, wherein the time when the device starts is detected as an opportunity that requires the time correction. The opportunity detection step includes
The time synchronization method according to any one of claims 24 to 33, wherein a time when an operation for changing a time and a time zone of the internal clock is received is detected as an opportunity for the time correction. The opportunity detection step includes
The time stamp of the file and the directory stored in the storage medium accessible to the device is compared with the time of the device measured by the internal clock to determine the time stamp of the file and the directory. ,
As a result of the determination, if the time stamp of the file and the directory is later than the time of the own device, or if it is past the predetermined time, the time correction is necessary. 35. The time synchronization method according to claim 24, wherein the time synchronization method is detected. The opportunity detection step includes
The time included in the content of data held by the own device is compared with the time of the own device measured by the internal clock, and the time contained in the content of data held by the own device is determined. Judgment
As a result of the determination, when the time included in the content of the data held by the own device is later than the time of the own device, or when the time is past the predetermined time, The time synchronization method according to any one of claims 24 to 35, wherein the time synchronization method is detected as an opportunity that requires time correction. The opportunity detection step includes
The time when there is an inquiry from the lower device about the time of the own device is detected as an opportunity for the time correction,
38. The method according to claim 24, further comprising: a response step of responding to the time of the own device in response to an inquiry from the lower device after the time of the own device is corrected by the time correcting step. The time synchronization method according to claim 1. As a result of time correction by the time correction step, if the time of the device itself is normal,
38. The method according to claim 24, further comprising a first time abnormality notification step of notifying the other device of time abnormality of the other device or expiration of an electronic certificate of the other device. The time synchronization method according to claim 1. As a result of time correction by the time correction step, when the time of the internal clock has returned to the default,
A second time abnormality notification step of detecting an abnormality of the internal battery for maintaining the internal clock when the power of the own device is not turned on and notifying the host device that manages the own device to that effect The time synchronization method according to any one of claims 24 to 38, wherein: The time correction step includes
The time required for reception processing during time inquiry communication to the host device that manages the device itself is measured using a monotonically increasing clock that is not affected by the internal clock, and the measurement result is used as a time lag caused by communication processing. The time synchronization method according to any one of claims 24 to 39, wherein the time correction is performed after being added to the time acquired from the host device.   Of the accuracy of the internal clock and the accuracy of the internal clock of the host device that manages the device, up to ± N (N: a predetermined number) times the minimum digit of the coarser accuracy is used as the allowable time error. 41. The time synchronization method according to claim 25, further comprising an allowable time error setting step that can be set.   When acquiring the time of the host device from the host device, the authenticity of the time of the host device is protected by using mutual authentication and encrypted communication using an electronic certificate, and the time of the host device The time synchronization method according to any one of claims 24 to 41, further comprising: a security step that prevents falsification of the time. Even after the time correction by the time correction step, the time of the own device falls under the expiration of the electronic certificate held by the own device for performing encrypted communication with the other device,
An electronic certificate issuance requesting step for requesting issuance of a new electronic certificate by encrypted communication using a special electronic certificate that is not time-checked to the host device that manages the self-device. The time synchronization method according to any one of claims 24 to 42. Even after the time correction is performed by the time correction step, if the time of the file or data stored in the storage medium accessible by the own device or the own device is abnormal,
Based on the importance of the file or the data, a file / data deletion / updating step for deleting or updating the file or the data, or the time of the file or the data with respect to a host system managing the device 44. The time synchronization method according to claim 24, further comprising a third time abnormality notification step for notifying abnormality. If you are unable to renew an expired digital certificate,
A self-device stop notification step of notifying the stop of the self-device in encrypted communication using a special electronic certificate that is not time-checked to the other device;
After notifying by the own device stop notification step, the own device stop step of stopping the own device;
The own device stop notification step for notifying the stop of the own device;
The time synchronization method according to any one of claims 24 to 44, further comprising: When a time synchronization device that measures the time of its own device using an internal clock communicates with another device, it acquires the time of the host device that manages the device and synchronizes the time with the other device. A program for
In the time synchronization device,
Trigger detection processing for detecting a trigger that requires time correction of the internal clock;
A time correction process for correcting the time of the own apparatus to the time of the host apparatus, as a time correction of the internal clock, when an opportunity requiring the time correction is detected by the trigger detection process;
A program characterized in that is executed. The trigger detection process is
The time of the host device acquired from the host device is compared with the time of the host device measured by the internal clock, and it is determined whether or not the difference between both times is within a predetermined allowable time error range. And
47. The program according to claim 46, which is a process of detecting when the time correction is necessary when a difference between the two times is not within the range of the allowable time error as a result of the determination. The trigger detection process is
48. The program according to claim 46 or 47, which is a process of detecting when the predetermined information is stored in a storage medium together with the time of the higher-level device acquired from the higher-level device as an opportunity that requires the time correction. . The trigger detection process is
The self device compares the expiration date of the electronic certificate held for performing encrypted communication with the other device and the time of the self device measured by the internal clock, and the time of the self device is the electronic device. Determine if it is within the validity period of the certificate,
The process according to any one of claims 46 to 48, wherein, as a result of the determination, the process detects a case where the time of the self-device is not within the validity period of the electronic certificate as a trigger that requires the time correction. The program according to any one of the above items. The trigger detection process is
When the device itself performs encrypted communication with the other device using the electronic certificate, the expiration date of the electronic certificate sent from the other device, and the time of the device measured by the internal clock To determine whether the time of the device is within the validity period of the electronic certificate,
The process according to any one of claims 46 to 49, wherein as a result of the determination, the time of the device itself is not within the validity period of the electronic certificate, and is detected as a trigger that requires time correction. The program according to any one of the above items. The trigger detection process is
When communicating with a lower device managed by the own device, the time of the lower device included in the information sent from the lower device is compared with the time of the own device measured by the internal clock. , Determine the time of the subordinate device,
As a result of the determination, processing for detecting when the time of the lower device is in the future than the time of the own device, or when it is in the past of a predetermined time, as an opportunity for the time correction. The program according to any one of claims 46 to 50, wherein: The trigger detection process is
When communicating with the other device, the time stamp of the packet sent from the other device is compared with the time of the own device measured by the internal clock, and the difference between the two times is a predetermined allowable time error. Determine whether it is within range,
The process according to any one of claims 46 to 51, wherein as a result of the determination, a case where the difference between the two times is not within the range of the allowable time error is detected as an opportunity for the time correction. The program described in the section. The trigger detection process is
53. The process according to any one of claims 46 to 52, wherein the process detects a time when the time correction is necessary when a notification that the time of the own device is abnormal is received from the other device. The program described in. The trigger detection process is
54. The processing according to any one of claims 46 to 53, wherein the processing detects a fixed period measured by a timer using a monotonically increasing clock that is not affected by the internal clock as a trigger that requires time correction. The program described in. The trigger detection process is
55. The program according to any one of claims 46 to 54, wherein the program is a process of detecting when the own apparatus is activated as an opportunity that requires the time correction. The trigger detection process is
The program according to any one of claims 46 to 55, which is a process of detecting when an operation of changing the time and time zone of the internal clock is received as an opportunity that requires the time correction. . The trigger detection process is
The time stamp of the file and the directory stored in the storage medium accessible to the device is compared with the time of the device measured by the internal clock to determine the time stamp of the file and the directory. ,
As a result of the determination, if the time stamp of the file and the directory is later than the time of the own device, or if it is past the predetermined time, the time correction is necessary. The program according to any one of claims 46 to 56, wherein the program is a detection process. The trigger detection process is
The time included in the content of data held by the own device is compared with the time of the own device measured by the internal clock, and the time contained in the content of data held by the own device is determined. Judgment
As a result of the determination, when the time included in the content of the data held by the own device is later than the time of the own device, or when the time is past the predetermined time, 58. The program according to any one of claims 46 to 57, wherein the program is a process of detecting a trigger that requires time correction. The trigger detection process is
When there is an inquiry from the lower-level device about the time of the own device, the detection process is triggered by the need for the time correction,
In the time synchronization device,
60. The response process of responding to the time of the own apparatus in response to an inquiry from the lower apparatus after the time of the own apparatus is corrected by the time correction process. The program according to any one of the above items. As a result of time correction by the time correction process, when the time of the device itself is normal,
In the time synchronization device,
60. The first apparatus according to claim 46, further comprising: causing the other apparatus to execute a first time abnormality notification process for notifying the time abnormality of the other apparatus or the expiration date of the electronic certificate of the other apparatus. The program according to any one of the above items. As a result of time correction by the time correction process, when the time of the internal clock has returned to the default,
In the time synchronization device,
When the self-device is not powered on, it is detected as an abnormality in the built-in battery for maintaining the internal clock, and a second time abnormality notification process for notifying the host device that manages the self-device is performed. The program according to any one of claims 46 to 60, wherein the program is executed. The time correction process is:
The time required for reception processing during time inquiry communication to the host device that manages the device itself is measured using a monotonically increasing clock that is not affected by the internal clock, and the measurement result is used as a time lag caused by communication processing. 62. The program according to claim 46, wherein the time correction is performed after adding to the time acquired from the host device. In the time synchronization device,
Of the accuracy of the internal clock and the accuracy of the internal clock of the host device that manages the device, up to ± N (N: a predetermined number) times the minimum digit of the coarser accuracy is used as the allowable time error. 63. The program according to claim 47, wherein an allowable time error setting process that can be set is executed. In the time synchronization device,
When acquiring the time of the host device from the host device, the authenticity of the time of the host device is protected by using mutual authentication and encrypted communication using an electronic certificate, and the time of the host device 64. The program according to any one of claims 46 to 63, wherein security processing for preventing falsification is executed. Even after the time correction is performed by the time correction process, the time of the own device corresponds to the expiration of the electronic certificate held by the own device for performing encrypted communication with the other device,
In the time synchronization device,
A higher-level device that manages the device itself is caused to execute an electronic certificate issuance request process for requesting the issuance of a new electronic certificate by encrypted communication using a special electronic certificate that is not time-checked. The program according to any one of claims 46 to 64. Even when the time correction is performed by the time correction process, when the time of the file or data stored in the storage medium accessible by the own device or the own device is abnormal,
In the time synchronization device,
Based on the importance of the file or the data, a file / data deletion / updating process for deleting or updating the file or the data, or the time of the file or the data with respect to a host system managing the device The program according to any one of claims 46 to 65, wherein a third time abnormality notification process for notifying abnormality is executed. If you are unable to renew an expired digital certificate,
In the time synchronization device,
Self-device stop notification processing for notifying the stop of the self-device in encrypted communication using a special electronic certificate that is not time-checked to the other device;
After notifying by the own device stop notification process, the own device stop process for stopping the own device;
Own device stop notification processing for notifying the stop of the own device;
The program according to any one of claims 46 to 66, wherein the program is executed.

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