JP2940541B1 - E-mail client device and recording medium on which the program is recorded - Google Patents

Abstract

An electronic mail client device capable of acquiring the current time without relying on a circuit for updating the current time during power-off, and having a small memory size and a small circuit size. A control unit (17) of a client device (1) instructs a mail communication unit (11) to send an electronic mail (4) addressed to itself to a mail server (2) and then read the electronic mail addressed to itself from the mail server (2). . When receiving the electronic mail 4, the mail server 2 records the reception time in the header portion 41, stores it as the electronic mail 5, and sends back the electronic mail 5 in response to a request from the client device 1. On the other hand, the mail communication unit 1 of the client device 1
1 receives the e-mail 5, the time setting unit 16
Extracts the time at which the mail server 2 received the electronic mail 5 from the header portion 51, and sets the received time as the current time in the time processing unit 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic mail client device having an electronic mail client function, and more particularly, to an electronic mail client capable of acquiring the current time without relying on a circuit for updating the current time during power-off. The present invention relates to a client device and a recording medium on which the program is recorded.

[0002]

2. Description of the Related Art An e-mail client device capable of sending and receiving e-mails by communicating with a mail server has been conventionally used.
Widely used. In recent years, with the rapid spread of the Internet, portable client devices are also being used, and the client function of e-mail is also being added to electronic devices for other uses, such as routers and mobile phones. It is in.

On the other hand, many electronic devices including a client device have a function of displaying or acquiring the current time. For example, in an electronic mail client device, a creation time and a reception time are attached to the electronic mail, and the new or old of the electronic mail is determined based on the time. Also, on mobile phones, etc., the time of arrival is displayed,
When storing the call history, a function of acquiring the current time is used. Further, this function is used not only for the purpose of the electronic device but also for notifying the user of the current time.

Here, if each electronic device is operating,
The elapsed time from a certain time can be easily known by a counter or a timer realized by hardware or software. However, in order to obtain the current time, a reference time must be set at least once. Further, when the counter or the timer is stopped, for example, when the power supply of the electronic device is cut off, it is necessary to reset the time.

Therefore, in the conventional client device, the following three methods are mainly used to implement the above functions. The first method is that the user sets the current time every time the power of the client device is turned on. The second method is, for example, RTC
In this method, a (real time clock) chip or the like is provided, and the RTC chip is backed up by a battery. According to this method, the RTC chip keeps updating the current time even when the power of the client device is off. This allows the current time value to be retained even during the power-off period. Further, as a third method, N
There is a method of mounting a protocol dedicated to time acquisition, such as TP (Network Time Protocol). A client device equipped with NTP communicates with a time server via a network. Thus, if a time server is provided on the network, the correct current time can be obtained from the time server.

[0006]

However, the above-mentioned conventional client device has a problem that the time required for setting the time, the circuit scale, or the software scale is likely to increase.

[0007] Specifically, when the first method is adopted, the user needs to manually input the current time every time the power of the client device is turned on, which is very troublesome. Further, in the second method, since the RTC chip and the backup battery are indispensable, the number of components constituting the client device increases, and the manufacturing cost tends to increase. Further, when the third method is adopted, it is necessary to newly provide a time server on the network. In addition, since it is necessary to mount a protocol dedicated to time acquisition, the amount of memory required for the client device increases, which leads to an increase in cost.

In particular, in the case of a portable client device or an electronic device with a client function added, the amount of memory and circuit size available for time acquisition are limited in terms of manufacturing cost, device size and weight, and the like. It is often done. Therefore, these client devices require, for example, a memory amount of 50 kilobytes or more.
In some cases, a dedicated circuit such as a TP or an RTC chip cannot be mounted.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and has as its object to obtain a current time without relying on a circuit for updating the current time while the power is turned off, and to provide a necessary memory. An object of the present invention is to realize an electronic mail client device having a small volume and a small circuit size, and a recording medium on which the program is recorded.

[0010]

According to a first aspect of the present invention, there is provided an e-mail client apparatus for transmitting / receiving an e-mail to / from a mail server in accordance with a predetermined e-mail transmission / reception protocol. An e-mail client device provided with a communication means for transmitting an e-mail addressed to the user to the mail server; and
Control means for instructing the communication means to receive the e-mail from the mail server, and from a portion of the received e-mail specified by the protocol,
And a time setting means for extracting a time at which the mail server receives the electronic mail and setting a current time based on the reception time.

In the electronic mail client device having the above configuration (hereinafter abbreviated as a client device), when the current time needs to be acquired, for example, when the power is turned on and the current time is not set, the control means is provided. Instruct the communication means to send an e-mail addressed to the user to the mail server. When the e-mail is received by the mail server, the reception time is recorded in a predetermined portion (such as a header portion), and is stored so that the e-mail can be retrieved in response to a request from the client device.

Further, the control means of the client device includes:
The communication means is instructed to read the e-mail from the mail server. Accordingly, the communication unit instructs the mail server to send the electronic mail, and the mail server sends the stored electronic mail to the client device.

When the communication means receives the e-mail, the time setting means extracts the reception time from the predetermined portion and, for example, extracts the reception time as it is or adds an offset time to the reception time. , Set the current time of the client device. The client device may send and receive an e-mail to obtain the current time every time the current time is required, or may obtain a later current time based on the time obtained by the e-mail. .

According to the above configuration, since the current time is set by sending and receiving the e-mail, the communication means for sending and receiving the e-mail can be shared for both sending and receiving the e-mail and setting the time. In addition, processing such as instructing the communication means and extracting the reception time is simpler than communication processing such as a dedicated protocol for sending and receiving e-mails and obtaining time, for example. It can be realized by a small program or circuit. As a result, the amount of memory and the circuit scale required for the program can be significantly reduced as compared with the case where the dedicated protocol is added to the e-mail client device.

Further, in the above configuration, the client device can acquire the current time without updating the current time while the power is off. As a result, a circuit for updating the current time even when the power is turned off, such as an RTC chip, becomes unnecessary. In addition, since it is not necessary to manually set the current time every time the power is turned on, the time and effort required when the power is turned on can be reduced.

The time acquired by the client device can be used for setting the time when the current time updating circuit itself is started, and for correcting an error in the circuit. Therefore, the accuracy of the circuit for updating the current time can be improved with a smaller amount of memory and a smaller circuit size than in the case where a dedicated protocol is added, and the trouble in setting can be reduced.

Here, the recording of the reception time is extremely effective for tracking the transmission route of the electronic mail, and is provided in almost all mail servers as a basic function of the mail server. Therefore, a mail server similar to the conventional mail server can be used as the mail server of the client device. Further, unlike the case where the dedicated protocol is used, there is no need to provide a server dedicated to time acquisition. As a result, since the client device can be connected without particularly changing the network, the trouble of installing the client device can be reduced to the same level as the client device having the current time updating circuit.

By the way, for example, when the processing speed of the mail server is low, the time from when the mail server receives an electronic mail until it can be sent out becomes long. This time varies depending not only on the processing capacity of the mail server but also on the usage status of the mail server, such as the processing performed by the mail server simultaneously with the processing of the e-mail. Therefore, if the client device sets the reception time as it is as the current time, or adds a fixed offset time to the reception time to make the current time, the error may increase.

On the other hand, in the electronic mail client device according to the second aspect of the present invention, in the configuration of the first aspect, when the communication means fails to receive the transmitted electronic mail, Adjustment means for adjusting the offset time between the current time set by the time setting means and the reception time according to the success or failure of the reception of the mail again is further provided. .

In the above configuration, the communication means of the client device repeatedly tries to receive the electronic mail until the electronic mail is successfully received. On the other hand, the adjusting means counts the number of times of reception failure, or increases the offset time for each failure, for example, to determine the offset time when the time setting means sets the current time as the success or failure of reception. Adjust accordingly.

Thus, the client device can adjust the length of the offset time according to the time until the mail server can send out the e-mail. As a result, when setting the current time, errors due to the processing speed of the mail server can be reduced. Therefore, even when the mail server is connected to a mail server having a different processing speed, or when the processing speed greatly varies depending on the use status of the mail server, a client device with a small time error can be realized.

On the other hand, a recording medium on which the program according to the third aspect of the present invention is recorded is a recording medium on which a program for causing a computer to operate as an e-mail client device is recorded. A sending step of sending an e-mail addressed to the user to a mail server, a receiving step of receiving the e-mail from the mail server, and a part of the received e-mail specified by the protocol, A program for executing an extraction step of extracting the time at which the server has received the electronic mail and a time setting step of setting the current time based on the extracted reception time is recorded.

In the above configuration, when the program is read from the recording medium and executed by a computer, the computer can operate as a client device. The client device performs the above steps, sends an e-mail addressed to itself to the mail server, and reads the e-mail. Here, when the e-mail is received, the mail server records the reception time in a predetermined portion such as a header portion. Therefore, in the e-mail received by the client device from the mail server, the reception time is recorded in the relevant portion.
Further, the client device extracts the reception time from the above-described portion of the electronic mail, and sets the current time based on the reception time.

As a result, by executing the above program, the present time can be obtained without relying on a circuit for updating the time while the power is turned off, and the memory can be implemented with a smaller amount of memory. An electronic mail client device can be realized.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] An embodiment of the present invention will be described below with reference to FIGS. That is, as shown in FIG. 1, the network system according to the present embodiment is a client-server type network system capable of sending and receiving e-mail, and includes an e-mail client device 1, a mail server 2, And a network 3 provided in the network. In the network system according to the present embodiment, a mail address is assigned to each client device 1 in advance, and, for example, POP (Post Office Protocol) is used as a protocol for sending and receiving e-mail.
3 and SMTP (Simple Mail Transfer Protocol). Thereby, the client device 1
The e-mail 4 is transmitted to the mail server 2 via the network 3, and the e-mail 5 arriving at the mail server 2 is received from the mail server 2. In the present embodiment, a local area network is used as an example of the network 3, and the transmission delay between the client device 1 and the mail server 2 is set to be extremely small.

Here, the format of the electronic mail 4 (5) transmitted and received in the present embodiment will be briefly described. That is,
The electronic mail 4 (5) according to the present embodiment is, for example, RF
C (Request For Comments) 822 and the like, and are described in a mail format that is standardly used on the Internet.
1) and the remaining mail body 42 (52). The header portion 41 is provided with an arbitrary number of fields including a field name arranged at the beginning of a line, a character ":" serving as a separator, and a character string indicating the contents of the field following the field name. For example, the field indicating the destination of the electronic mail 4 (5) is described as "To: mail address".

The header portion 41 (51) includes:
A Received field indicating a delivery route of the electronic mail 4 (5) is provided. Specifically, for example, SMTP
A network device that communicates according to the protocol, regardless of whether it is a network device that accepts a response or final delivery, inserts the Received field at the beginning of the header 41 (51) of the received e-mail 4 (5). Is required. This Received field is described in the format of “Received: information of receiving network device; reception time”. For example, the IP address (U
RL), not only information indicating the receiving network device itself, but also the receiving network device
The time when (5) is received is also described as a character string or a numerical value string. This reception time is usually date, time,
Includes days of the week, time of day, etc. Therefore, the administrator of the network system can send the e-mail 4 (5) when a failure occurs in the network system, for example.
By referring to each Received field included in the header part 41 (51) of the e-mail 4 (5)
Of the delivery route.

Here, the mail server 2 communicates with the client device 1 and other network devices (not shown) via the network 3 to send e-mails 4.5.
And a spool 22 for storing the received e-mail 4. The e-mail communication unit 21 can communicate with the client device 1 or the like according to the e-mail transmission / reception protocol. When the e-mail 4 is received, the e-mail communication unit 21 transmits the e-mail 4 based on the header portion 41 of the e-mail 4. The e-mail 4 can be stored in the spool 22 so that the e-mail address is identified and the relation with the e-mail address can be recognized. In addition, the mail communication unit 21 can record the reception time by adding a Received field to the head of the header portion 41 as described above. Further, the mail communication unit 21 can send out the electronic mail 5 addressed to the mail address assigned to the client device 1 among the electronic mails stored in the spool 22 in response to a request from the client device 1.

On the other hand, the client device 1 according to the present embodiment is, for example, an electronic device such as an e-mail terminal, a router, a printer, or a mobile phone having an e-mail client function. A mail communication unit (communication means) 11 for communicating with
A time processing unit 12 that outputs the current time in response to an inquiry from another member.

The mail communication unit 11 sends the e-mail 4 to the mail server 2 according to a predetermined e-mail transmission / reception protocol, as well as the e-mail communication unit 21, and stores the e-mail 4 stored in the mail server 2. The electronic mail 5 addressed to can be read from the mail server 2.

In the mail communication section 11 or a control section 17 described later, information for communicating with the mail server 2 and information for reading out an electronic mail addressed to the mail server 2 are recorded. The former information includes, for example, the IP address of the mail server 2. The latter information includes the mail address assigned to the client device 1 and the mail server 2 when reading the e-mail to the mail address. And the password sent to the user. These pieces of information are necessary information in the case of an e-mail client device, and are used not only at the time of setting a time to be described later but also at the time of sending and receiving a normal e-mail.

Further, the time processing unit 12 includes, for example, a tick counter 13 for increasing a count value (tick value) at predetermined time intervals, a reference time storage unit 14 for storing a reference time, and a tick value. A calculation unit 15 that outputs the current time based on the reference time. The count value of the tick counter 13 is reset to 0 when the current time is stored in the reference time storage unit 14, and thereafter increases at predetermined time intervals, for example, 100 ticks per second. On the other hand, when the time output is instructed, the calculation unit 15 refers to the count value of the tick counter 13 and multiplies the count value by the time interval, for example, to calculate the elapsed time from the reference time. Is calculated. Further, the calculation unit 15 adds the reference time stored in the reference time storage unit 14 and the elapsed time. Thus, the time processing unit 12 can output the current time.

In the present embodiment, for example, there is no means for causing the tick counter 13 to count while the power of the client device 1 is off, such as a backup power supply. Therefore, the tick counter 13 starts counting after the power of the client device 1 is turned on.
Until the reference time is set in the reference time storage unit 14, the time processing unit 12 cannot output a correct current time.

Here, in addition to the above configuration, the client device 1 according to the present embodiment sets the current time in the time processing unit 12 based on the header portion 51 of the e-mail 5 received by the mail communication unit 11. Time setting unit (time setting means) 16 to perform, the mail communication unit 11 and the time setting unit 1
A control unit (control means) 17 for instructing the setting of the current time to 6
Are provided. Note that, of course, the control unit 17
May be actively issued to each of the members 11 and 16 or may be in response to an inquiry from each of the members 11 and 16.

More specifically, the time setting section 16 sets the first Receive section in the header section 51 of the E-mail 5.
The reception time of the mail server 2 is extracted from the d field. As described above, the Received field is described, for example, as "Received: information on the receiving network device; reception time". For example, if the character string from the end of the field to ";" is extracted, The reception time can be extracted very easily. The time setting unit 16
Writes the time extracted from the e-mail 5 into the reference time storage unit 14 of the time processing unit 12. The time setting unit 16 converts the time extracted from the e-mail 5 into a format that can be stored in the reference time storage unit 14 as necessary.

On the other hand, when the correct time is not set in the time processing unit 12, for example, when the client device 1 is activated, the control unit 17 instructs the mail communication unit 11 to send the electronic mail 4 addressed to itself. To the mail server 2. Further, after sending out the e-mail 4, it is possible to instruct the mail communication section 11 to read out the e-mail 4 from the mail server 2. Since the mail server 2 attaches the reception time to the received e-mail 4 and stores it as the e-mail 5, the mail communication unit 11 actually reads the e-mail 5.

Here, the content of the electronic mail 4 sent by the mail communication unit 11 is not limited as long as it is an electronic mail addressed to itself. In this case, the mail communication unit 11 and the control unit 17
Identifies an electronic mail for time setting based on, for example, whether or not the transmission destination is its own mail address.
However, the e-mail 4 transmitted and received at the time of setting the time, for example, the title (Subject) of the header portion 41 and the contents of the mail body 42 are determined in advance so as to be easily distinguished from other e-mails. Is good.

Each of the units 11 to 17 may be a functional block realized by a CPU executing a predetermined program, or may be a circuit that performs the same operation. However, when realized by software, the client device 1 can be realized only by distributing the above programs via a recording medium or a communication path and causing a computer having a communication function to execute the programs. Therefore, it can be distributed more easily than in the case of realizing by hardware.

The operation when setting the time of the client device 1 in the network system having the above configuration will be described below with reference to FIG. That is, for example, when the correct time is not stored in the reference time storage unit 14 of the time processing unit 12 such as when the client device 1 is started, the control unit 17 instructs the mail communication unit 11 to An e-mail 4 addressed to the user is transmitted (S1a). In S1b, the mail server 2
Receives the e-mail 4, the mail communication unit 21 processes the e-mail 4 according to the SMTP protocol in S2b, and a Received field including the reception time is added to the head of the header 41 of the e-mail 4. . Thereby, the reception time is attached to the electronic mail 4. Further, the mail communication unit 21 determines in S3b that
The electronic mail 4 to which the reception time is attached is stored in the spool 22 as the electronic mail 5.

On the other hand, in the client device 1, the control unit 17 instructs the mail communication unit 11 to send the reception request of the e-mail 4 sent in S1a to the mail server 2 (S2a). Upon receiving the reception request (S4b), the mail server 2 reads the electronic mail 5 from the spool 22 and sends it to the client device 1 (S5b). Header part 5 of the e-mail 5
1 also includes the reception time attached in S2b.

In the client device 1, when the e-mail 5 is received by the mail communication unit 11 in S3a, the time setting unit 16 sends the e-mail 5 from the header 51 of the e-mail 5 to the e-mail server 2 in S4a. 4 is extracted. Further, the time setting unit 1
6 stores the extracted reception time as the current time in the reference time storage unit 14 of the time processing unit 12 (S5a). The tick counter 13 clears the tick value to 0 when the time (reference time) is set in the reference time storage unit 14.

Here, in the time processing unit 12, the tick counter 13 increases the tick value at predetermined time intervals while the power of the client device 1 is on. Therefore, after the reference time is set, the calculation unit 15 can output a correct current time based on the reference time and the tick value.

In the above configuration, when the correct time is not set in the time processing unit 12, the transmission and reception of the e-mail
The time of the time processing unit 12 is set. Therefore, the client device 1 does not need to provide a battery-backed RTC chip in order to obtain the correct time. In addition, even though the RTC chip is not provided, it is not necessary to manually set the time in the time processing unit 12 every time the client device 1 is started, so that the trouble at the time of turning on the power can be reduced.

Here, when the current time is set by adding a dedicated protocol such as NTP to the client device (comparative example), a program for communicating with the time server according to NTP is required. Since this program needs to process communication for time acquisition by itself, it usually consumes a memory amount of 50 kilobytes or more. On the other hand, electronic devices that do not have an external recording device and store data in semiconductor memory, such as printer servers, routers, or embedded electronic devices, are limited in the amount of memory that can be installed, and have an e-mail client function. In many cases, for example, the amount of memory that can be used for a program for realizing the function of acquiring time and time is limited to about 500 kilobytes or less. Therefore, in general, it is difficult to divide the memory amount of 50 kilobytes only for obtaining the current time.

On the other hand, in the client device 1 according to the present embodiment, the communication processing is performed by the existing mail communication unit 11.
The newly provided time setting unit 16 and control unit 17 instruct the mail communication unit 11 to perform communication,
It is only necessary to extract the reception time from the electronic mail 5 received by the mail communication unit 11. These processes are simpler than the communication processes, and can be realized by, for example, a program of 5 kilobytes or less. As a result, the amount of memory required for the client device 1 can be greatly reduced to one-tenth or less as compared with the case where the NTP is provided. The program can be implemented without any trouble.

Further, recording of the reception time is extremely effective for tracking the transmission route of the electronic mail, and is provided in almost all mail servers as a basic function of the mail server 2. Therefore, a mail server similar to the conventional one can be used as the mail server 2 of the client device 1. In addition, unlike the case where the dedicated protocol is used, there is no need to provide a time server dedicated to time acquisition. As a result, the client device 1 can be connected without particularly changing the network system, so that the trouble of installing the client device 1 can be reduced to the same level as the client device having the RTC chip.

[Second Embodiment] In the above description, when the client device 1 succeeds in receiving the electronic mail 5, that is, when the mail server 2 has a sufficient processing speed, the client device 1 A case has been described in which the mail server 2 can send the e-mail 5 before the user requests the reception of the e-mail 5.

However, as the processing speed of the mail server 2 decreases, the time from when the mail server 2 receives the e-mail 4 to when the e-mail 5 can be transmitted becomes longer. As a result, even when the reception request is received, the e-mail 5 may not be transmitted.

Here, the period from when the e-mail 4 is sent to when the reception request is issued is set in advance to a length corresponding to the processing speed of the mail server 2, and the time setting unit 16
If the time obtained by adding the reception time and the period (offset time) is set as the current time, the client device 1
An e-mail 5 can be received.

However, the processing speed of the mail server 2 varies not only with the processing capacity of the mail server 2 itself but also with the amount of processing that the mail server 2 processes in parallel with the reception of the e-mail 4. In order to receive the e-mail 5, the period must be set sufficiently long. On the other hand, the time processing unit 12 cannot output the correct current time until the correct time is set after this period has elapsed. Therefore, in order to make the time processing unit 12 operate normally at an earlier time, It is better to set the above period short. As a result, it is difficult to set this period to an appropriate length.

On the other hand, in the present embodiment, a client device capable of setting the current time at the earliest possible time regardless of the processing speed of the mail server 2 will be described with reference to FIGS. That is, as shown in FIG. 3, the client device 1a according to the present embodiment includes
A control unit 17a is provided in place of the control unit 17 shown in FIG. 2. When reception fails, an instruction is sent to the mail communication unit 11 after a predetermined time T [seconds] has elapsed, and the e-mail 5 is sent.
Can be resent.

A retry counter 18a realized by software or hardware is newly provided to count the number of retransmissions (retry times) of a reception request. Further, the time setting unit 16a provided in place of the time setting unit 16 adjusts the time set in the time processing unit 12 by adding an offset time corresponding to the number of retries to the reception time extracted from the electronic mail 5. I do.

The time setting section 16a and the retry counter 18a correspond to the adjusting means described in the claims. Further, since the remaining configuration is the same as that of FIG. 1, members having the same functions are denoted by the same reference numerals, and description thereof will be omitted.

In the above configuration, instead of the processing shown in FIG.
The processing shown in FIG. 4 is performed. In FIG. 4, only steps performed by the client device 1a are described for convenience of explanation. That is, as in FIG. 2, the mail communication unit 11 of the client device 1a sends out the e-mail 4 in S1a and S2a in accordance with the instruction of the control unit 17a (at time t1 shown in FIG. 5). 5 is requested (at time t2). Further, in S11a, the mail communication unit 11 determines whether the reception of the electronic mail 5 has been successful.

Here, the mail server 2 processes the electronic mail 4 during the period from the time point t1 to the time point t4, and cannot send out the electronic mail 5 as shown by the broken arrow in FIG. As a result, the client device 1a fails to receive the e-mail 5 at time t2.

If the reception of the e-mail 5 fails (the above S
11a), retry counter 18a
Increases the number of retries in S12a. Furthermore, in S13a, the control unit 17a, the number of retries, whether exceeds the specified number S ₀ defined in advance is determined. If not exceeded the specified number of times S _0, the control unit 17a, in S14a, the predetermined time (T seconds)
After waiting until elapses, the process of S2a is performed,
Attempt to receive the e-mail 5 again (at time t3). The processing of S2a, S11a to S14a is repeated until the reception of the e-mail 5 is successful.

At time t4, the mail server 2
When the e-mail 5 can be transmitted, and thereafter, at time t5, a reception request is received from the client apparatus 1a, the e-mail 5 is transmitted in response to the request (indicated by a solid arrow in the figure).

When the client device 1a succeeds in receiving the e-mail 5 (YES in S11a), the time setting unit 16 extracts the reception time from the e-mail 5 as in FIG. 2 (S4a). Further, the time setting unit 16
The time of the time processing unit 12 is set based on the offset time according to the number of retries and the reception time (S15).
a).

For example, when the number of retries is S, that is, when the retry is successful at the S-th time, the time (from t2 to t5) from when the client device 1a first transmits the reception request to when it finally transmits the reception request. Time) is T × S
Seconds. Therefore, the time setting unit 16a adds T × S seconds as the offset time to the reception time, and sets the obtained time as the current time in the time processing unit 12.

As a result, when setting the time in the time processing unit 12, an error caused by the time from when the mail server 2 receives the e-mail 4 to when the e-mail 5 is sent out is canceled. As a result, an accurate time can always be set even when the processing speed of the mail server 2 fluctuates. In addition, in order to reliably receive the e-mail 5 even when the processing speed of the mail server 2 becomes slow, the client device 1a has an earlier You can get the current time with.

By the way, if the reception of the electronic mail 5 is not successful even if it is repeated the specified number of times S ₀ (in the above-mentioned S13a)
In the case of (YES), the electronic mail 4 may not reach the mail server 2 due to, for example, a failure in the network 3. In this case, the client device 1a repeats the processing after step S1a and resends the electronic mail 4 addressed to itself. Thus, even if a failure occurs temporarily in the network 3, the current time can be obtained without any trouble.

In the present embodiment, the retry counter (18a) counts the number of retries, and the time setting unit (1
6a) calculates the offset time according to the number of retries, but the method of adjusting the offset time is not limited to this. For example, instead of providing a retry counter, the offset time may be stored, and the offset time may be increased each time a failure occurs. Further, the time until the retry may be changed according to the success or failure of the reception. If the offset time can be adjusted according to the success or failure of the reception, the same effect as in the present embodiment can be obtained.

In the first and second embodiments, the control unit (17.17a) instructs acquisition of the reference time at the time of activation, but the timing of instructing acquisition is not limited to this. Absent. For example, the reference time storage unit (1
The necessity and timing of time acquisition may be instructed based on the reference time and the like stored in 4).

Further, in each of the above embodiments, the configuration including the reference time storage unit and the like has been described as an example of the time processing unit (12), but the present invention is not limited to this. For example, a storage unit that stores a value indicating the current time may be provided, and the current time value may be updated at predetermined time intervals. In this case, the time setting unit (16 / 16a) sends the e-mail (5)
If the current time value in the storage unit is set based on the reception time extracted from, the current time can be set. In this configuration, the client device (1.1a) acquires the current time by referring to the current time value in the storage unit. In any configuration, the same effect as in each embodiment can be obtained as long as the current time can be output and the current time can be set from the outside when requested from each member of the client device.

In each of the above embodiments, the case where the client device and the mail server (2) are included in the same network system has been described as an example. However, the present invention is not limited to this. It may be. If both can send and receive e-mail, the same effect can be obtained. However, if they are included in different network systems, there is a possibility that an error may occur due to a delay in the e-mail. Therefore, it is desirable to reduce the distance between the two so that no delay occurs.

By the way, in each of the above embodiments, the case where the operation of the time processing unit is stopped while the power of the client device is off has been described as an example in order to simplify the circuit configuration of the client device. However, the present invention is not limited to this. According to the present invention, the following effects can be obtained even when the time processing unit is realized by hardware such as an RTC chip backed up by a battery.

Specifically, with the above hardware,
If the time processing unit is operated even during the period when the power of the client device is off, the time processing unit can always update the current time regardless of whether the client device is on or off. However, even in this case, setting of the current time is indispensable at the time when the time processing unit starts operating, such as when manufacturing the time processing unit or when replacing the battery. Furthermore, the error between the time output by the time processing unit and the actual time increases as the elapsed time after setting the time increases. For example, in the case of a general RTC chip, if the time in year units elapses after setting the time, an error in minutes may occur. Therefore, in order to improve the accuracy, it is better to reset the time after a certain amount of time has elapsed even when an RTC chip is provided.

Here, the client device according to each of the above-described embodiments sets the current time of the client device of the electronic mail by sending and receiving the electronic mail. Thus, the amount of memory and the circuit scale can be reduced as compared with the case where a dedicated protocol is used. As a result, the time accuracy can be improved without increasing the amount of memory, the circuit scale, and the time and effort for setting the time.

In each of the above embodiments, SMTP has been described as an example of an e-mail sending / receiving protocol, but the present invention is not limited to this. Further, the format of the e-mail is not limited to the above-mentioned format. If the network system adopts a protocol for adding a reception time to a received electronic mail, the same effects as those of the above embodiments can be obtained.

[0070]

As described above, the electronic mail client device according to the first aspect of the present invention sends an electronic mail addressed to itself to the mail server and receives the electronic mail from the mail server. , And time setting means for setting the current time based on the reception time extracted from the received electronic mail.

According to this configuration, the current time is set by sending and receiving the electronic mail, and the communication means for sending and receiving the electronic mail can be shared for both the sending and receiving of the electronic mail and the setting of the time. As a result, it is possible to obtain the current time without relying on the circuit for updating the time while the power is turned off, and to achieve an electronic mail client device that can be implemented with a smaller memory size and a smaller circuit scale. Also,
Since it is not necessary to newly provide a server for acquiring time, it is possible to reduce the time and effort required to install an e-mail client device.

As described above, in the electronic mail client device according to the second aspect of the present invention, in the configuration of the first aspect of the present invention, when the communication means fails to receive the transmitted electronic mail, An attempt is made to receive the mail again, and an adjusting means for adjusting an offset between the current time set by the time setting means and the receiving time according to the success or failure of the reception is provided.

According to the above configuration, the e-mail client device can adjust the length of the offset according to the time until the mail server can send the e-mail. As a result, there is an effect that the time can be set more accurately.

As described above, the recording medium storing the program according to the third aspect of the present invention transmits the electronic mail addressed to itself to the mail server, and receives the electronic mail from the mail server. A program for executing a receiving step, an extracting step of extracting a time at which the mail server receives the e-mail from the received e-mail, and a time setting step of setting a current time based on the extracted receiving time Is recorded.

Therefore, by executing the above program, the present time can be obtained without relying on the circuit for updating the time during power-off, and the memory can be implemented with a smaller amount of memory. This has the effect of realizing an electronic mail client device.

[Brief description of the drawings]

FIG. 1 illustrates one embodiment of the present invention, and is a block diagram illustrating a main configuration of a network system including an e-mail client device and a mail server.

FIG. 2 is a flowchart showing an operation of the network system.

FIG. 3 illustrates another embodiment of the present invention, and is a block diagram illustrating a main configuration of a network system including an e-mail client device and a mail server.

FIG. 4 is a flowchart showing an operation of a client device in the network system.

FIG. 5 is a timing chart showing an operation when the client device fails to receive an e-mail in the network system.

[Explanation of symbols]

 1. 1a E-mail client device 2 Mail server 11 Mail communication unit (communication unit) 16 Time setting unit (Time setting unit) 16a Time setting unit (Time setting unit; adjusting unit) 17.17a Control unit (Control unit) 18a Retry counter (adjustment means)

Continuation of front page (56) Reference RFC 868 (Network Working Group Request for Comments: 868), J. Am. Postel, K .; Harrens Tien, "Time Protocol", May 1983 RFC867 (Network Working Group Request for Comments: 867), J. Am. Postel, "Daytime Protocol", May 1983 (58) Fields investigated (Int. Cl. ⁶ , DB name) H04L 12/54 H04L 12/58 G04G 5/00

Claims (3)

(57) [Claims] An e-mail client device provided with communication means for transmitting / receiving an e-mail to / from a mail server in accordance with a predetermined e-mail transmission / reception protocol, sends an e-mail addressed to the user to the mail server. And control means for instructing the communication means to receive the e-mail from the mail server, and the mail server transmits the e-mail from a portion of the received e-mail specified by the protocol. An e-mail client device comprising: time setting means for extracting a reception time and setting a current time based on the reception time. 2. The communication means, if reception of the transmitted e-mail fails, attempts to receive the e-mail again, and further sets the current time set by the time setting means according to the success or failure of the reception. 2. The e-mail client device according to claim 1, further comprising an adjusting unit for adjusting an offset time from the reception time. 3. A recording medium on which a program for operating a computer is recorded as an e-mail client device for transmitting / receiving an e-mail to / from a mail server in accordance with a predetermined e-mail transmission / reception protocol. A sending step of sending an e-mail addressed to the mail server, a receiving step of receiving the e-mail from the mail server, and a step defined by the protocol of the received e-mail, the mail server A recording medium storing a program for executing an extraction step of extracting a time at which an electronic mail was received, and a time setting step of setting a current time based on the extracted reception time.