JP2002341072A - Method for correcting time - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve a cost problem of a real time clock to correct time by receiving a reference time by a radio wave or the like. SOLUTION: An image forming device 100 obtains the estimated error of a RTC 127 from a PDA 120, and if the estimated error of a RTC 104 is bigger, it obtains the present time of the RTC 127 from the PDA 120 to correct the time of the RTC 104. In addition, the corrected time is memorized in a RAM 102, and the estimated error of the RTC 127 is memorized in the RAM 102 as the present estimated error of the RTC 104. The estimated error of the RTC 104 is found from an elapsed time from when the RTC 104 was corrected last time, the accuracy of RTC, and the estimated error at the time when the RTC 104 was corrected last time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a time correction method for a device having a time measuring means.

[0002]

2. Description of the Related Art Conventionally, copiers and facsimile machines have a configuration in which a real-time clock is incorporated and operates according to time. That is, facsimile transmission and reception can be performed and the power supply of the apparatus can be controlled at the designated time.

[0003]

The real-time clock built in the digital copying machine is difficult to maintain sufficient accuracy, because the amount of heat generated varies depending on the operation status of the apparatus and the temperature changes greatly. Was.

The real-time clock itself is based on a transmitter using a crystal oscillator, and is configured to always measure the current time by combining a backup battery. Since the number is affected, a time error occurs.

A method of detecting a temperature change to correct an error and a method of correcting a time by receiving a reference time by radio waves or the like have been devised, but have had a problem in terms of cost.

[0006]

According to the present invention, in order to solve the above-mentioned problems, it is determined that the first estimated time error of the first device is larger than the second estimated time error of the second device. In this case, the time of the first timekeeping means of the first device is corrected based on the time of the second timekeeping means of the second device, and the error information of the first timekeeping means is updated. With such a configuration, the above problem is solved.

[0007]

FIG. 1 shows an image forming apparatus 100 and a portable personal information terminal (Persona) embodying the present invention.
l Digital Assistant, PD
A) shows the configuration of 120.

In the image forming apparatus 100 shown in FIG.
1 is a processor (hereinafter referred to as CPU), 102 is a memory (hereinafter referred to as RAM) for storing data and image signals, 103 is a nonvolatile memory (hereinafter referred to as ROM) for storing programs and data, and 104 is a real-time clock (hereinafter referred to as RT).
C), 105 is a battery for backing up the RAM 101 and RTC 104 as a battery, 106 is a wireless LAN interface, 107 is a network control unit (hereinafter NCU) for connecting to a public line, 108 is a scanner, 1
Reference numeral 09 denotes a printer, and 110 denotes a user interface (hereinafter, UI).

Further, in the PDA 120, 121 is C
PU, 122 is RAM, 123 is ROM, 124 is an operation battery, 125 is a standard radio wave receiving circuit, 126 is a wireless LA
N interface, 127 is RTC, 128 is UI.

The CPU 101 controls the image forming apparatus 100, and performs processing according to a program stored in the ROM 103.

When a user gives an instruction for copying from the UI 110, the original image is read by the scanner 108, the image signal is received and stored in the RAM 102, and then the image signal is sent to the printer 109 to prevent image formation. , Realizes a copying operation.

When a facsimile transmission instruction is issued from the UI 110, the CPU 101 performs predetermined encoding on the document image data read by the scanner 108, and then uses the NCU 109 to send the destination image using the public line. A facsimile transmission is executed by calling a facsimile and transferring data.

The wireless LAN interface 106
When print data is received from the host computer via the printer, the printer 109 forms an image and executes a print function.

The RTC 104 is backed up by a battery 105 and constantly counts time even when the power of the apparatus is turned off, and functions as a reference for time-based operations such as transmission of a designated time of facsimile. .

The RAM 102 is backed up by a battery 105 and stores data even when the power of the apparatus is turned off.

The wireless LAN interface 106 has a function of communicating with other electronic devices, and transmits and receives signals using weak radio waves. When electronic devices having a compatible wireless LAN interface enter a communicable area, a communication link is established between them.

The PDA 120 performs operations such as displaying stored data in accordance with a user's instruction input from the UI 128 and sounding a schedule alarm based on the alarm setting of the RTC 127. Battery 1
24, the RTC 127 and the RAM 122 are backed up by a battery, the RTC 127 always holds the time, and the RAM 122 stores data.

The standard radio wave receiving circuit 205 receives a JG2AS radio wave transmitting a standard time using an atomic clock in Japan in a long wave band in Japan, and converts the time information superimposed on the received radio wave in real time. Is to be extracted. Therefore, the CPU 121 can obtain time information with zero error while the standard radio wave is being received. The CPU 121 executes the RTC once every hour, for example.
127 is corrected and the time at which the correction is performed is represented by R
Record in AM122. At this time, since the error of the time source is extremely small, it is recorded as 0.

The image forming apparatus 100 obtains the estimation error of the RTC 127 from the PDA 120, and if the estimation error of the RTC 104 is larger,
127, the current time is acquired, and the time of the RTC 104 is corrected. Further, the time at which the correction was performed is stored in the RAM 102, and the estimated error of the RTC 127 is stored in the RAM 102 as the current estimated error of the RTC 104. RTC104
Is obtained from the elapsed time since the previous RTC 104 was corrected, the accuracy of the RTC, and the estimated error when the previous RTC 104 was corrected.

Next, taking the image forming apparatus 100 as an example, R
Time correction information stored in the AM 102, RTC10
The accuracy information of No. 4 will be described.

The RAM 102 stores TIME (1) as one of the variables of the time correction information, which indicates when the last time correction was performed.

This variable stores the date and time. Therefore, how much time has passed since the last time correction of the RTC at a certain time is determined by the RTC1.
It can be calculated by taking the difference between (1) and the current time indicated by 04.

The RAM 102 stores A (ppm) (2) as another variable of the time correction information, which is a variable indicating the accuracy of the time source used for the correction.

This variable indicates the magnitude of the error that the RTC 104 has in ppm, that is, in parts per million.
Regarding this accuracy, the worst value in the specification of the RTC itself can be stored, and the RTC can be set for each device.
The actual accuracy of C may be measured and its value may be stored.

The RAM 102 stores ERROR (seconds) (3) as an included error when the time is corrected.

This variable is error information of the time information used for reference when the time is corrected. If the time information source referred to is a standard radio wave such as the PDA 120, this error ERROR is zero, and if the time is corrected based on the time information obtained from a device having other included errors, the error information is used. It is something to memorize. In addition, if the user manually sets the time from the UI, it is not possible to determine whether the user has input the time signal exactly according to the time signal or based on an incorrect clock, so it is possible to set the time manually. The maximum value is stored.

The RAM 122 of the PDA 120 stores R
Time TIME, RTC1 at which time correction of TC127 was performed
An accuracy A (ppm) of 27 and an included error ERROR at the time of performing the time correction (if it may be zero, it is not necessary to store it).

Next, the procedure of time correction performed by the image forming apparatus 100 under the control of the CPU 101 will be described with reference to the flowchart of FIG. FIG. 2 shows a part of a program of the CPU 101 which is a computer.
The ROM 103 is a storage medium that stores the program of FIG.

This program is transmitted from the wireless LAN interface 106 or the NCU 107 to the RAM 10
2 and the CPU 101 may read out from the RAM 102 and use it.

The image forming apparatus 100 may be provided with an interface for reading this program from a storage medium such as a floppy (registered trademark) disk or a compact disk. In this case, a storage medium such as a floppy disk or a compact disk corresponds to a storage medium storing the program of FIG.

When the image forming apparatus 100 and the PDA 120 are brought close to a distance at which the wireless LAN interface can communicate, the apparatuses are authenticated at S200 and communication is established.

Subsequently, in S201, the image forming apparatus 100
Sends a command to the PDA 120 to inquire whether the PDA 120 has time information (whether or not it has the RTC 127). If the PDA 120 does not have the RTC 127, the time correction procedure ends according to the determination in S202.

If the PDA 120 has the RTC 127, the process proceeds to S203, where the estimation error of the current time of the PDA 120 is obtained.

The estimated error of the current time of the RTC built in each device can be obtained by (A) × (current time−TIME) / 1,000,000 + ERROR (4).

Here, A, TIME, and ERROR are values stored in the RAM 102 and the RAM 122 by the image forming apparatus 100 and the PDA 120, respectively.

[0036] The PDA 120 can execute its own RT upon request.
The estimation error of C127 is calculated and transmitted. RTC127
The estimation error of the current time of RTC
The difference between the correction time TIME stored in the AM 122 (the time obtained by correcting the time of the RTC 127 after receiving the standard time signal) (that is, the elapsed time since the previous correction of the RTC 127) is multiplied by the accuracy of the RTC 127, and Further, if necessary, the error can be obtained by adding an error ERROR (an error of the time measuring means (atomic clock described above) on which the RTC 127 is corrected).

On the other hand, in step S203, the image forming apparatus 100 acquires an estimation error of the current time of the PDA 120. Then, the image forming apparatus 100 uses its own RTC 1
04, the estimation error of PDA1 is calculated in S204.
The estimated time error of 20 and the estimated time error of its own current time are compared. Note that the estimation error of the current time of the RTC 104 is the difference between the current time of the RTC 104 and the correction time TIME stored in the RAM (the time at which the time of the RTC 104 was corrected last time) (that is, the elapsed time since the correction of the RTC 104 last time). Time) multiplied by the accuracy of the RTC 104,
Further, if necessary, the error ERROR (previous RTC1
When the correction of the RTC 104 is also performed based on the RTC 127 of the PDA 120, the correction of S203
The error of the RTC 127 obtained in step (1), and can be obtained by adding the error of the RTC 104 immediately after the previous time correction.

As a result of the comparison in S204, the image forming apparatus 10
0 indicates that the estimation error of the RTC 104 built in the own device is PDA
If it is determined that the error is larger than the estimation error of the RTC 127 of the PDA 120, the PDA 120
It requests the current time of C127 and corrects the time of its own RTC 104 using the obtained current time. At this time, S
At 206, the correction time TIME is simultaneously stored in the RAM 10
2 and the PDA 12 acquired in S203.
The estimation error of the RTC 127 of 0 is stored in the RAM 102 as a new ERROR.

Conversely, if it is determined in step S204 that the estimation error of the PDA 120 is larger, the image forming apparatus 100
Does nothing as its own device and ends the time correction.

Although the above processing describes the operation viewed from the image processing 100 side, similarly, when the PDA 120 performs the time correction operation, the image forming apparatus 10 described in the above description will be described.
The PDA 120 corrects the built-in RTC 127 by performing the same operation by exchanging the roles of the PDA 120 and 0.

According to the above procedure, when the time accuracy of the PDA 120 is high, the image forming apparatus 100 performs the correction based on the time of the PDA 120, and can perform the correction at a more accurate time.

Note that, instead of acquiring the current time of the PDA 120 in step S205, the image forming apparatus 100 proceeds to step S203.
In step S204, both the estimation error of the PDA 120 and the current time are acquired, and if it is determined in step S204 that the estimation error of the partner is smaller, the time of the RTC 104 may be corrected.

Also, without inquiring that the time information is held in S201, the device holding the time information notifies the other party of the current time and the estimated error in the device authentication in S200. Is also good.

Generally, a wireless LAN is a network composed of a plurality of devices. Therefore, when at least one device such as the PDA 120 capable of using accurate time information exists in the wireless LAN network, the entire device is Time accuracy can be dramatically improved. In the above description, the communication between the devices is performed by the wireless LAN interface, but other communication means may be used as long as short-range communication can be performed, and it is also effective to use an infrared communication interface.

The present invention can be applied to apparatuses other than the image forming apparatus.

Although the above embodiment has been described assuming that time correction is automatically performed, the
The correction operation may be performed when an instruction to execute the time correction is explicitly given from 0, the UI 128, or the like.

Alternatively, the time may be corrected after it is determined that the estimation error of the built-in RTC exceeds a predetermined value.

[0048]

As described above, the first device of the first device
If it is determined that the estimated time error of the second device is larger than the second estimated time error of the second device, the time of the first device based on the time of the second timekeeping means of the second device is determined. By configuring the first clock means to correct the time and updating the accuracy information of the first clock means, there is an effect that the time precision can be improved.

[Brief description of the drawings]

FIG. 1 is a block diagram of an image forming apparatus and a PDA embodying the present invention.

FIG. 2 is a flowchart illustrating an operation of time correction.

[Explanation of symbols]

 101, 121 CPU 102, 122 RAM 103, 123 ROM 104, 127 Real-time clock (RTC) 106, 126 Wireless LAN interface 125 Standard radio wave receiving circuit

Continued on front page F term (reference) 2F002 AA00 AD06 AD07 BB04 BB05 DA00 FA16 GA06 GC22 2H027 DA38 DA50 DE04 DE07 DE09 EC06 EC10 EC20 EE08 EE10 HB07 HB09 HB17 JA11 JB30 JC20 ZA07 ZA09

Claims (9)

[Claims] The first estimated time error of the first device is the second estimated time error.
If it is determined that the time difference is larger than the second estimated time error of the second device, the first time counting means of the first device is set to the time based on the time of the second time counting device of the second device. A time correction method, wherein the correction is performed and the error information of the first timer is updated. 2. The method according to claim 1, wherein the first device comprises:
An elapsed time from a time at which the first clocking means is corrected,
A time correction method, comprising calculating an estimated time error of the first clock means from the accuracy of the first clock means and error information of the first clock means. 3. The time correction method according to claim 1, wherein the error information of the first timer is updated based on a second estimated time error. 4. The method according to claim 1, wherein:
A time correction method, wherein the first device and the second device communicate using radio waves. 5. The method according to claim 1, wherein:
A time correction method, wherein the first device and the second device communicate using infrared rays. 6. A time measuring means, an acquiring means for acquiring an estimation error of the current time of another device, and an estimation device of the other device when the estimation error of the time means is larger than the estimation error of the current time of the other device. A time correction device comprising: a control unit that corrects the clock unit based on a current time and updates an estimation error of the clock unit when the time is corrected based on an estimation error of a current time of another device. . 7. The timekeeping device according to claim 6, wherein the control unit is configured to determine the timing of the clock based on an elapsed time from a time at which the clocking unit is corrected, an accuracy of the clocking unit, and an estimation error of the clocking unit when correcting the time. A time correction apparatus for calculating an estimation error of a means. 8. A time correction program for a clock means or a storage medium storing the program, the estimation error of the current time of another device is obtained, and the estimation error of the clock means is the estimation error of the current time of the other device. If the difference is larger than the current time, the clock means is corrected based on the current time of another device, and the estimated error of the clock means when the time is corrected is updated based on the estimated error of the current time of the other device. Or a storage medium storing the program. 9. The method according to claim 8, wherein an estimated error of the time-measuring means is determined from an elapsed time from a time when the time-measuring means is corrected, an accuracy of the time-measuring means, and an estimated error of the time-measuring means at the time of time correction. A time correction program or a storage medium storing the time calculation program.