Radio-wave timepieces and time information receivers

When lack of a part data on a time code included in a received standard radio wave is detected, the lack is filled up with a corresponding data part of another time code. The time of a radio-wave timepiece is corrected in accordance with the time code whose lack has been filled up.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications Nos. 2004-288931, 2004-351256, and 2004-380110, filed on September, 30, December, 3, and December, 12, respectively, 2004, entire contents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radio-wave receivers, radio-wave timepieces, and radio-wave reception integrated circuits.

2. Background Art

At present, standard radio waves including time codes are available in many countries including Germany, Great Britain, Switzerland and Japan in the world. In Japan, long-wave standard radio waves of 40 and 60 kHz amplitude-modulated with time code formats transmitted by two transmission stations installed in Fukushima and Saga prefectures are available. Each time a unit digit of a number indicative of minutes of correct time is updated, or at intervals of one minute, a time code of the radio wave is sent out in the form of a frame of 60 seconds.

At present, radio-wave timepieces are commercially available which receive the standard radio waves and correct the time that they count (hereinafter referred often to as “internal time” of the timepieces) (see TOKKAIHEIS 7-198878, 5-157859 and -142363 publications).

Generally, the radio-wave timepieces receive the standard radio waves at a predetermined time, for example at 2 o'clock, once per day. The reason for this is that time correction made substantially once per day suffices for accurate timekeeping in terms of an error involving the time counting and a time interval at which the time correction is performed. Reception of the radio waves at all times for time correction would increase power consumed in the radio-wave reception circuits of the timepieces.

However, with a radio-wave timepiece of the wristwatch type, power consumption is a problem that directly involves the continuously operable time of the wristwatch. Thus, even more reduction of the power consumption is required. To this end, various techniques are invented in which the operating time of the radio-wave reception circuit is minimized as much as possible. For example, an invention is known in which correction of the whole internal time by receiving the whole time code involving one frame included in the standard radio wave and correction of the “second” part of the internal time by using a signal called an M signal appearing when the time code is switched are selectively employed as requested (see TOKKAI 2000-235093 publication).

At least 60 seconds are required for receiving the whole time code. Actually, reception of the radio wave must continue for more than 120 seconds because a time required for the receiving operation of the radio wave reception circuit to be stabilized and a margin time required for receiving a time code for at least one frame should be considered. When the M signal described in TOKKAI 2000-235093 publication is received, the standard radio wave must be received continuously until the M signal is received and if the time required for the receiving operation of the radio wave reception circuit to be stabilized is considered, the reception of the radio wave must continue for a time corresponding to at least one frame. Thus, the time for receiving the standard radio wave is still large.

It is an object of the present invention to provide radio-wave receivers, radio-wave timepieces and time reception apparatus in which reduced time and hence power consumption are required for reception of the standard radio wave for use in time correction.

SUMMARY OF THE INVENTION

In one aspect, part of a transmitted standard radio wave that includes time data modulated in units of a frame is received. Then, a particular one of a plurality of items of identification data disposed at predetermined intervals of time in the frame is detected. Time being counted is then corrected based on a time when the particular one of identification data was detected.

In another aspect, a standard radio wave carrying a standard time code having a normalized standard time format is received. Time counted is corrected by applying a quantity of time correction to the counted time in accordance with the time code of the received radio wave such that the counted time coincides with the time of the received radio wave. An expected date when an error involving the time counted becomes a predetermined error limit time is then calculated based on the time when the time counted was corrected and the correction time applied to the counted time. Responsive to the time counted arriving at the expected date, the standard radio wave is received and the time counted is then corrected in accordance with a time code of the received standard radio wave.

In a further aspect, a standard radio wave is received and a time code is then acquired from the radio wave. Possible lack of o'clock and minute data included in the acquired time code is then detected. Responsive to detection of the lack of o'clock and minute data, the standard radio wave is received again, thereby acquiring a new time code from the radio wave. The lack of o'clock and minute data is filled up based on the first-mentioned and new time codes acquired. The time being counted is then corrected with the time code whose lack of o'clock and minute data was filled up.

DETAILED DESCRIPTION OF THE INVENTION

Like reference numerals are used to denote like parts of the drawings showing several embodiments and modifications. Thus, when an element of one embodiment or modification is described, further description of a like element of another embodiment or modification will be omitted. Note that the latter element performs a similar function to that performed by the former element.

First, a time code indicative of time information generated from the standard radio wave will be described. The time code has a format shown inFIG. 1and is generated as a frame at a cycle of 60 seconds. In the format, an M signal pulse that is a head marker of a pulse width of 0.2 seconds is created at a start point of the frame. In addition, 6 P signals P1, P2, P3, P4, P5and P0each having a pulse width of 0.2 seconds are generated at time intervals of 10 seconds; that is, in 9th, 19th, 29th, 39th, 49th and 59th second locations after the start point of time.

One second after this frame, a next M signal pulse of a 0.2 second width appears at the start point of a next frame. That is, when two pulses of a 0.2 second width appear successively, a frame boundary is recognized therebetween and the position of the latter signal, or M signal, indicates an accurate update time of the minute unit digit of the present frame. In the frame, minute, o'clock, day of the calendar year in AD (counted from January, 1), lower two ones of digits indicative of the year, and day of the week data involving the time when the frame starts are arranged in a BCD notation in 1st-8th, 12th-18th, 22th-33th, 40th-48th and 50th-52nd second locations, respectively. In this case, logics 1 and 0 are represented by pulses of 0.5 and 0.8 second widths, respectively. The frame ofFIG. 1illustrates data on 114th day of the year, 17:25.

The features of the time code format are shown inFIG. 1. As shown inFIG. 1, the P signals are disposed at intervals of 10 seconds. Thus, when the time is corrected using the standard radio wave, the time can be corrected at high speed by using a (9th “second”) P1signal if the error is within ±5 seconds. The M signal is disposed only in a 0th second location, representing the start time of a correct minute. Thus, when the time is corrected in accordance with the standard radio wave, the time can be corrected at high speed using the M signal if the error involving the time being counted is within ±30 seconds.

As described above, by using the features of the time code in combination, the time being counted can be corrected at high speed without receiving the whole time code of one frame. An error involving the time being counted by a time counter provided within a general timepiece is approximately ±15 seconds per month. Thus, even when the radio wave timepiece receives the standard radio wave once per week, the error involving the counted time falls usually within ±5 seconds. Thus, in the present embodiment, high speed time correction by paying attention to the P signal will be described.

First Embodiment

A Radio-Wave timepiece of a Radio Wave Receiver according to the present invention will be described with reference to the drawings.

The first embodiment of the present invention is directed to correction of a “second” part of the internal time being counted by a time counter with a particular one of the P signals included in a received standard radio wave.

FIG. 2is a block diagram of a radio-wave timepiece1of the present embodiment. Timepiece1comprises a CPU10, an input unit20, a display30, a ROM40, a RAM50, a radio-wave reception circuit60, a time code generator70, an oscillator90, a time counter80that counts clock pulses generated by oscillator90to provide data on the present time, and a bus100that electrically connects these elements.

Input unit20comprises switches to give commands to perform the respective functions of the timepiece. When a user depresses the respective switches, they output corresponding command signals to CPU10.

Display30comprises, for example, an LCD or a segmented display that digitally displays the present date based on display data from CPU10.

ROM40has mainly stored a system program involving the radio wave timepiece and application programs including, especially, a first standard radio wave reception program402.

RAM50temporarily stores various programs to be executed by CPU10and data involving the execution of these programs. In the embodiment, the previous internal time corrected based on the received standard radio wave is stored as previous corrected time data502. For example, the internal time of radio-wave timepiece1is corrected or initialized by receiving the whole time code for one frame at least once, and this corrected internal time is then stored as previous corrected time data502.

CPU10reads the respective programs stored in ROM40at predetermined times or in response to corresponding operational signals received from input unit20, loads them on RAM50, and then gives commands and transfers data concerned to the respective functional elements of the timepiece based on the programs. For example, CPU10controls radio-wave reception circuit60to receive the standard radio wave. CPU10also corrects time data that represents the internal time being counted by time counter80based on a time record received from time code generator70and then updates a displayed present date based on the corrected time data.

CPU10executes a first standard radio-wave reception process (seeFIG. 3) in accordance with a corresponding program402stored in ROM20. More specifically, CPU10calculates an error comprising the difference between the previous corrected time and the present internal time multiplied by a maximum error per unit-time that can occur in the time counter80and is obtained from the time-counting accuracy of the time counter80. In addition, CPU10detects a P signal from the received standard radio wave and then corrects the “second” part of the internal time when the P signal was detected.

Radio-wave receiver60extracts only a signal of desired frequency components from the signals received by antenna ANT, detects this signal, and then outputs it to time code generator70. In this case, a time lag extending from the start of the reception of the radio wave to generation of a time code is greatly reduced by performing a high-speed AGC operation based on TOKKAIS 2004-242157 and -179948 publications.

Time code generator70detects time information based on the signal outputted from radio-wave reception circuit60, generates a time code as required and then outputs it to CPU10.

Time counter80counts clock pulses outputted from oscillator90, thereby obtaining present-time data representing the internal time of radio-wave timepiece1, and then outputs it to CPU10. Oscillator90comprises a crystal oscillator that provides clock pulses of a fixed frequency at all times to time counter80.

A first standard radio-wave reception process will be described with reference to a flowchart ofFIG. 3. This process is performed when CPU10executes first standard radio-wave reception program402stored in ROM40, as described above.

First, CPU10calculates a difference R between a previous corrected time502stored in RAM50and the present time counted by time counter80(step A10). Then, CPU10multiplies the maximum error per unit time by R calculated in step A10, thereby calculating an error involving the time counted by time counter80(step A12) The maximum error per unit time comprises an error per unit time obtained based on the time counting accuracy of time counter80. That is, it is an error occurring in time counter80per unit time (for example, of 1 second), or an error per second to which the error of ±15 seconds per month occurring in the internal time is reduced.

Then, CPU10determines whether the error calculated in step A12is within ±5 seconds (step A14). If not (No in step A14), CPU10performs another time correction method which comprises correcting the time being counted based on time information on received frames1-3, as performed in the past.

On the other hand, when the error calculated in step A12is within ±5 seconds (Yes in step A14), CPU10causes radio-wave reception circuit60to start to receive the standard radio wave (step A16). A signal indicative of the received standard radio wave is outputted to time code generator70as required. Circuit70generates a time code from the received signal as required and then outputs it to CPU10(step A18). Then, CPU10detects an earlier appearing one of P signals included in the time code received from circuit70(step A20).

If the unit digit of the “second” part of the internal time is any one of “5”-“9” when the P signal is detected (Yes in step A22), the unit digit of the “second” part of the internal time is changed to 0 (seconds) by moving a figure indicative of the “second” part of the internal time one place to the left one second after the P signal was detected (step A24). When the internal time is 5 seconds slow compared with the time of the standard radio wave, the internal time is corrected by setting the internal time forward.

On the other hand, the unit digit of the “second” part of the internal time is any one of 0-4 when the P signal is detected, or when the internal time is less than 5 seconds fast compared with the received standard time (No in step A22), the unit digit is changed to 0 (seconds) without moving the figure indicative of the “second” part of the internal time one place to the left one second after the P signal was detected (step A26). That is, when the internal time is less than 5 seconds fast compared with the time of the received standard radio wave, the internal time is corrected by being set back.

Then, CPU10causes radio-wave reception circuit60to terminate reception of the standard radio waves (step A28).

More specifically, when the calculated error is between 0 and −5 seconds, and for example, when the time counter80has counted, for example, “16 seconds” as the internal time at a time when a P signal (for example, represented by a pulse P2ofFIG. 1) was detected (or in a “19th second” location in the standard radio wave) (Yes in step A22), CPU10corrects the “second” part of the internal time to “20” (seconds) by moving its figure one place to the left one second after the P signal was detected (step A24). When the calculated error is between 0 and +5 seconds, or when the time counter80has counted, for example, “22” seconds as the internal time of the time counter80at a time when a P signal (represented, for example, by pulse P2ofFIG. 1) was detected (No in step A22), CPU10corrects the “second” part of the internal time to “20” seconds one second after the P signal was detected without moving the figure indicative of the “second” part of the internal time one place to the left (step A26).

As described above, according to the first embodiment, when it is assumed that the error involving the time being counted by the time counter80is within ±5 seconds compared with the time represented by the standard radio wave, a P signal can be detected from the received standard radio wave, and the time being counted by the time counter80can be corrected at the unit digit of the “second” part when the P signal was detected. Thus, when the time is corrected, the whole time code of one frame need not to be received, and time correction is achieved in a reduced time compared with the prior art in which the time correction is performed by receiving the whole time code of one frame.

Second Embodiment

A radio-wave timepiece of the present embodiment is obtained by replacing ROM40ofFIG. 2of the first embodiment by ROM42ofFIG. 4.

Referring toFIG. 4, ROM42has stored a second standard radio-wave reception program422. When a user gives a command to receive the standard radio-wave and then correct the time of the timepiece, CPU10executes program422, thereby performing a corresponding second standard radio-wave reception process. When in this process CPU10determines that an “o'clock” part of a time code of the received standard radio-wave coincides with that of the internal time of the timepiece, CPU10then detects a next appearing P signal and one second after this detection, sets the “second” part of the internal time to 20.00 seconds.

Then, the second standard radio-wave reception process will be described with respect to a flowchart ofFIG. 5. This process is performed when CPU10executes second standard radio-wave reception program422in ROM42.

First, CPU10calculates a difference R between previous corrected time502stored in ROM42and the present time counted by time counter80(step B8). Then, CPU10multiplies the maximum error per unit time by R calculated in step B10, and then adds a margin (of, for example, “1”) for the maximum error per unit time to a resulting value of the multiplication, thereby providing a result S (step B10).

Then, CPU10causes radio-wave reception circuit60to receive the standard radio-wave S seconds before a time indicating “o'clock” data of a time code of the standard radio-wave (step B14). A signal indicative of the received standard radio-wave is then outputted to time code generator70as required. This generator70then generates a time code in accordance with the received signal and outputs it to CPU10(step B16). Then, CPU10detects a P (more particularly, P1) signal included in the time code produced by time code generator70(step B18).

Then, CPU10compares the “o'clock” part of the time code following the P signal detected in step B18with that of the internal time of the timepiece counted by the time counter80to determine whether both the o'clock parts coincide (step B20). When CPU10determines that they do not coincide (No in step B22); CPU10causes radio-wave reception circuit60to stop reception of the standard radio-wave for a predetermined time and then repeats steps B14-B22. The predetermined time refers to a time for which CPU10must again wait for reception of next “o'clock” data, and for example, 50 seconds after which next “o'clock” data of the time code will appear again.

When CPU10determines that both the “o'clock” data coincide in step B20(Yes in step B22), CPU10detects a P signal following the “o'clock” data of the generated time code, and then one second later, sets the “second” part of the internal time to 20.00 seconds (step B26). CPU10then causes radio-wave reception circuit60to terminate reception of the standard radio wave (step B28).

More particularly,FIG. 6illustrates a part of the time code in which the second standard radio-wave reception process is performed between “15” and “16” (o'clock) of the internal time. CPU10causes radio-wave reception circuit60to start to receive the standard radio-wave at a time T7which is S seconds before a time T10when the expected “o'clock” starts. AP (more particularly, P1) signal is detected at a time T9, at which time CPU10reads “o'clock” data from a time code part following the P signal. The “o'clock” data included in the time code is “15”, which coincides with that indicating the “o'clock” of the internal time. Thus, CPU10waits detection of a next P signal. When CPU10detects the next P (more particularly, P2) signal at a time T19, CPU10sets a “second” part of the internal time to “20.00” seconds at a time T20one second after detection of P2signal.

As described above, according to the second embodiment, the “second” part of the internal time can be corrected when the “o'clock” data included in the time code of the standard radio-wave coincides with that of the internal time counted by time counter80. Since an error involving the internal time of a general time counter is approximately ±15 seconds per month, an error that will be produced even when the internal time is not corrected for one week will fall within ±5 seconds. Thus, the “o'clock” data included in the time code of the standard radio-wave coincides with that of the internal time of the timepiece, excluding under special conditions, and hence the time can be corrected efficiently with single reception of the standard radio-wave without greatly consuming power.

While in the embodiment the second standard radio-wave reception process is started in accordance with the user's command operation, thereby correcting the internal time of the timepiece, the second standard radio-wave reception process may be executed at a predetermined time, of course. More specifically, when the internal time arrives, for example, at 2.00 a.m., CPU10may execute the second standard radio-wave reception process automatically. In this case, in step B20, CPU10is required to determine whether the “o'clock” data of the time code coincides with “2 o'clock” of the standard radio wave being received automatically. In accordance with such arrangement, the internal time of the timepiece is corrected automatically every day and an error involving the internal time is reduced to a small one. Thus, the time required for receiving the standard radio-wave can be further reduced.

While in the second embodiment the “o'clock” data of the time code following the P signal is illustrated as compared with the “o'clock” part of the internal time counted by time counter80, a “minute” part of the time code preceding the P signal may be compared with that of the internal time counted by time counter80.

Third Embodiment

A radio-wave timepiece of the third embodiment is obtained by replacing ROM40ofFIG. 2in the first embodiment by a ROM44ofFIG. 7.

Referring toFIG. 7, ROM44has stored a third standard radio-wave reception program442to be executed by CPU10in the present embodiment, thereby performing a corresponding process. More specifically, when the unit digit of the “second” part of the internal time becomes 9, CPU10saves this digit as “9:00”. When radio-wave reception circuit60starts to receive the standard radio-wave and CPU10detects a rising edge of a P signal pulse, CPU10releases saving “9.00”, thereby restarting the time counting and correcting the internal time.

Time counter80of the third embodiment should be preset so as to have a fast error necessarily compared with the time of the received standard radio-wave.

The third standard radio-wave reception process will be described in detail with reference to a flowchart ofFIG. 8. As described above, this process is performed when CPU10of timepiece1executes third standard radio-wave reception program442.

First, CPU10calculates a difference R between a time indicated by previous corrected time data502stored in RAM50and the present time counted by time counter80(step C10). Then, CPU10determines whether a numerical value indicative of the product of the maximum error per unit time and difference R is less than 1 (second) (step C12). If not (No in step C12), CPU10performs another time correction method, for example, of correcting the internal time based on the above-mentioned first standard radio-wave processing method or time information on received frames1-3, as performed in the prior art.

When CPU10determines that the value indicative of the product is less than 1 second (Yes in step C12), CPU10causes radio-wave reception circuit60to start to receive the standard radio-wave (step C14). Then, CPU10waits until the unit digit of the “second” part of the internal time becomes “9” (Yes in step C16), at which time CPU10causes time counter80to stop time counting and to hold the “second” part of the internal time as “9.00”(step C18).

Then, CPU10causes radio-wave reception circuit60to start to receive the standard radio wave. When a rising edge of a P signal pulse included in the received radio wave is detected (Yes in step C20), CPU10causes time counter80to restart the time counting (step C22). Then, CPU10gives a command to radio-wave reception circuit60, causing radio-wave reception circuit60to terminate the reception of the radio wave (step C24).

A more specified example of this process will be described with reference toFIG. 9that illustrates a part of the time code. First, CPU10causes radio wave reception circuit60to start to receive the standard radio wave. Reference character T1denotes a time when the unit digit of the “second” part of the internal time became “9”. Since time counter80has the fast error, the time of the standard radio wave has not yet arrived at time “9”. At this time T1, CPU10causes time counter80to stop the time counting and then causes same to hold the “second” part of the internal time at this time. CPU10then detects a rising edge of a P (or more particularly P2) signal at a time T2, at which time CPU10causes time counter80to restart the time counting.

While description has been made specifically in the case of P2signal with respect toFIG. 9, the same applies to in the case of each of signals P0-P5.

As described above, according to the third embodiment, if the unit digit of the “second” part of the internal time becomes “9” when the error is within 1 second, time counter80is caused to stop the time counting and when a P signal is then detected, to restart the time counting, thereby correcting the internal time. Thus, reception of the standard radio wave is achieved in a very short time.

While in the third embodiment the time counting is illustrated as restarted immediately after a rising edge of the P signal pulse is detected, the time may be corrected at a predetermined time, for example, one second after the P signal is received, by considering a time lag involving correction of the internal time. For example, when occurrence of a time lag of 50 milliseconds is considered, a figure indicative of the internal time may be moved one place to the left 950 milliseconds after the P signal was received, thereby changing the unit digit of the internal time to “0”(seconds), which brings about an exact internal time.

While in the third embodiment time counter80is illustrated as having a fast error, it may have a slow error, of course. In this case, reception of the standard radio wave should be started at a time when the unit digit of the “second” part of the internal time becomes “8”, and then the unit digit of the “second” part of the internal time should be changed to “9” when a rising edge of the P signal pulse is detected.

While in the third embodiment the time is illustrated as corrected in accordance with the standard radio wave available in Japan, it can be similarly corrected in accordance with a standard radio wave available in a foreign country.

Note that since the time code format of the standard radio wave varies from country to country, the timepiece need be changed in design so as to adapt to the time code format of the standard radio wave in the foreign county concerned.

FIGS. 10A-10Cillustrate parts of time code formats JJY, WWVB and DCF77 used in Japan, USA, and Germany, respectively. As shown inFIG. 10A, in Japan a pulse signal rises at a “0” second position of its code format while in USA and Germany a pulse signal falls at a “second” position of its time code format. Thus, in order to detect a P signal pulse of the time code in USA, design of the timepiece should be changed such that an end or falling edge of the pulse signal can be detected.

On the other hand, as shown inFIG. 10C, no P signals are included in the Germany's time code. In this case, the internal time may be corrected by using appropriate “o'clock” time data. For example, inFIG. 10C, an M signal may be used as identification data to correct the internal time.

While in the third embodiment the time correction is illustrated by detecting the P signal once, the internal time may be corrected after a plurality of P signals are detected. In this case, reception of the standard radio wave for a long time is required compared with correction of the internal time using single reception of the radio wave, but accurate time correction is achieved even when the standard radio wave is not stabilized due to noise.

Fourth Embodiment

FIG. 11is a block diagram of a radio-wave timepiece1of the fourth embodiment.

The radio-wave timepiece1of the fourth embodiment is obtained by replacing ROM44and RAM50of the third embodiment ofFIG. 7with ROM40A and RAM50A ofFIG. 11, respectively.

In timepiece1, CPU10performs a limit error correction process based on a corresponding program41stored in ROM40A, thereby always monitoring whether a reception start date has come. If so, CPU10controls radio-wave reception circuit60so as to receive the standard radio wave. Then, time code generator circuit70receives the standard radio waves from reception circuit60and then generates a time code, based on which the internal time data (not shown) being counted by time counter circuit80is corrected. CPU10also outputs a time display signal based on the internal time data to display30, thereby updating the display time.

In order to automatically and securely correct an error involving the time counted by time counter80by receiving a part of one frame of the time code without receiving the whole frame of the time code, the error should be within a predetermined range, or a limit error. More specifically, in the present embodiment a limit error of ±8 seconds is employed to correct the error based on identification codes, or P signals, disposed at equal intervals of 10 seconds in the time code and other identification codes, or M signals, disposed at respective start points of the frames. That is, a maximum error is ±8 seconds (or 8 seconds fast or slow compared with the standard or correct time). As just described above, the errors include fast and slow errors. For error correction, these two errors should be discriminated. In the embodiment, they are discriminated based on the P and M signals included in the time code and are corrected in corresponding manners. An error involving the time being counted by the time counter built in the wristwatch is on the order of ±15 seconds per month. Thus, if timepiece1receives the standard radio wave once in two weeks, the error involving the time being counted falls usually within ±8 seconds.

In the limit error correction process, a time when the error should be corrected is estimated based on the time-counting accuracy of timepiece1and the limit error. In addition, a possible error is corrected on condition that the error is always smaller than the limit error. Thus, by performing the limit error correction process, the frequency and time of the radio-wave reception by radio-wave reception circuit60of timepiece1are restricted to minimum necessary ones.

A mechanism in which CPU10corrects a time-counting error within ±8 seconds in the limit error correction process is deeply involved in the format of time code of the standard radio wave whose part is shown inFIG. 17. When the “second” part of the reception start time is necessarily 0 (seconds), CPU10causes radio-wave reception circuit60to start to receive the radio wave between times T10and T11if the internal time has a fast error within 8 seconds compared with the normal time while CPU10causes radio-wave reception circuit60to start to receive the radio wave between times T13and T20if the time has a slow error within 8 seconds.

When radio-wave reception circuit60has started to receive the radio wave between times T10and T11, CPU10detects a P signal at T11and then an M signal at T12. On the other hand, when radio-wave reception circuit60has started to receive the radio wave between times T13and T20, CPU10detects a P signal at T21, but no M signal at T22.

Thus, when CPU10has detected the P signal and then a next pulse as an M signal, it is implied that the next pulse has risen at T13. When CPU10has detected a P signal, but no next pulse as an M signal, it is implied that the pulse has risen at T23. Thus, with a fast error, the “second” part of the internal time counted by time counter80is corrected to time T13at a rising edge of a pulse following time T12when the M signal was detected. With a slow error, the “second” part of the internal time is corrected to time T23at a rising edge of a pulse following time T22when no M signal was detected.

When the internal time being counted by time counter80involves no error, the standard radio wave starts to be received at time T12and an M signal is detected simultaneously. Since the P and M signals are the same 0.2 second wide pulse, however, detection of only the M signal is determined to be that of a P signal. Since no M signal is detected at a pulse following time T12when detection of the M signal was determined to be that of the P signal, this case has the same detection pattern as with the slow error. That is, there is a possibility that time T13will be wrongly determined as time T22. When the internal time being counted by time counter80involves no errors, the “second” part of the internal time at time T13is “01” while the “second” part of the internal time data at time T22when the internal time involves a slow error is any one of “02”-“09”. Thus, a case in which the internal time involves no errors can be discriminated from a second case in which the internal time involves a slow error.

As described above, CPU10determines whether the internal time involves either a fast error or a slow error based on whether a P signal is detected and then an M signal is detected as a following pulse, thereby eliminating an error within ±8 seconds involving the internal time being counted by time counter80.

RAM50A has stored various programs to be executed by CPU10and data involving the execution of these programs. InFIG. 11, ROM50A has stored reception start date data51and interval error data52involving the execution of the limit error correction process.

CPU10reads reception start date data51when executing the limit error correction process. As shown inFIGS. 12A and 12B, reception start date data51comprises a previous reception start date51aand a reception start date51b. Previous reception start date51arepresents the latest date when the standard radio wave was received in the limit error correction process. Reception start date51brepresent a date when the radio wave is expected to be received next time.

Time correction quantity data52represents a time quantity (in seconds) by which the internal time counted by time counter80was adjusted so as to coincide with the time of the standard radio wave received this time.

After causing radio-wave reception circuit60to receive the standard radio wave in the limit error correction process, CPU10calculates as a new reception start date51ban expected date when the time counting error becomes the limit error based on reception start date data51and time correction quantity data52obtained this time and then updates next reception start date data51. Then, CPU10monitors the date data when time counter80counts and then determines whether the date is reception start date51b.

Now, radio-wave reception circuit60, which is of the superheterodyne type, will be described with reference toFIG. 13. Circuit60comprises an antenna ANT, an RF amplifier611, filter circuits612,615and617, a frequency converter613, a local oscillator614, an IF amplifier616, an AGC (Auto Gain Control)618and a detector620.

Antenna ANT includes, for example, bar antennas for receiving the standard radio wave which is then converted to an electric signal.

RF amplifier611receives the electric signal from antenna ANT and an RF control signal f1output from AGC circuit618. RF amplifier611amplifies the signal from antenna ANT in accordance with RF control signal f1.

Filter612receives a signal from RF amplifier611, and outputs only frequencies of the signal in a predetermined frequency range by filtering out the frequency components outside the range.

Frequency converter613receives a signal from filter612and a local oscillation signal from local oscillator614and outputs an intermediate frequency signal based on the received signals.

Filter615receives the intermediate frequency signal from frequency converter613, and outputs only frequency components of the signal in a predetermined range whose center is the intermediate frequency.

IF amplifier616receives a signal from filter615and an IF control signal f2from AGC618, and amplifies and outputs the signal from filter615in accordance with IF control signal f2.

Filter617receives the signal from IF amplifier616, outputs only a signal comprising frequency components of the signal in a predetermined range.

Detector620comprises a carrier extractor621and a signal reproduction circuit622. Carrier extractor621is composed, for example, of a PLL (Phase Locked Loop) that receives signal a outputted from filter617and outputs a signal b that has the same phase as signal a and a fixed level used as a reference signal.

Signal reproduction circuit622receives signals a and b outputted from filter617and carrier extractor621, respectively, and outputs a reproduced signal g and a signal c1corresponding to a base band signal comprising a reproduced version of signal a.

AGC circuit618receives signals a and c1from filter617and signal reproduction circuit622, respectively, and outputs RF and IF gain control signals f1and f2that adjust the amplification degrees of RF and IF amplifiers611and616, respectively, in accordance with the level of signal a.

FIG. 14is a block diagram of carrier extractor621, signal reproduction circuit622and AGC circuit618of the present embodiment. As shown, carrier extractor621comprises a PD (Phase Detector)621a, an LPF (Low Pass Filter)621band an oscillator621c.

PD621areceives a signal a outputted from filter617and a signal outputted from oscillator621c, and compares the phases of these signals and outputs a signal indicative of a result of the comparison.

LPF621breceives from PD621athe signal indicative of the result of the comparison, and allows frequencies of the received signal in a predetermined low-frequency range to pass therethrough and filters out the other frequency components.

Oscillator621creceives a signal from LPF621b, and adjusts the phase of the oscillation signal in accordance with the received signal such that the oscillatory signal is synchronized with a carrier wave of an output signal b.

Signal reproduction circuit622comprises a multiplier622a, and LPFS622band622c. Multiplier622areceives signal a from filter617and signal b from oscillator621c, and multiplies signal a by signal b and outputs a resulting signal c.

LPF622breceives signal c from multiplier622a, allows frequency components of signal c in a predetermined low-frequency range to pass therethrough as a signal c1. That is, LPF622bfilters out high frequency components of signal a and outputs reproduced signal c1corresponding substantially to a base band signal of signal a.

LPF622creceives signal c1from LPF622b, allows frequency components of signal c1in a predetermined (low-frequency) range to pass therethrough as a signal g by filtering out the other frequency components. Signal g corresponds to a reproduced data signal involving the standard radio wave obtained from radio-wave reception circuit60.

AGC circuit618comprises an inverting amplifier618a, a multiplier618b, an AGC detector618c, an LPF618dand an AGC voltage generator618e.

Inverting amplifier618areceives signal c1from LPF622b, inverts and amplifies signal c1and outputs a resulting signal d.

Multiplier618breceives signal a from filter617and signal d from inverting amplifier618a, multiplies signal a by signal d, and outputs a resulting signal e.

AGC detector618creceives signal e outputted from multiplier618b, and (peak) rectifies signal e and outputs a resulting signal.

LPF618dreceives a signal from AGC detector618c, and allows frequency components of the received signal in a predetermined (low-frequency) range to pass therethrough by filtering out the other frequency components.

AGC voltage generator618ereceives the signal from LPF618d, and outputs RF and IF control signals f1and f2that control the amplification factors of RF and IF amplifiers611and616, respectively, in accordance with the level of the received signal.

Operation of radio-wave receiver circuit60will be described next with reference to a flowchart ofFIG. 15.FIG. 16schematically illustrates waveforms of the respective signals that flow through circuit60.

Referring toFIG. 15, the standard radio wave received by antenna ANT is converted to an electric signal that is then outputted to RF amplifier611, which amplifies or attenuates the received signal in accordance with RF control signal f1from AGC circuit618and outputs a resulting signal via filter612to frequency converter613.

Frequency converter613converts the receives signal to a predetermined intermediate frequency signal, which is then outputted via filter615to IF amplifier616. IF amplifier616amplifies or attenuates the received signal in accordance with IF control signal f2received from AGC circuit618, and outputs a resulting signal a via filter617to detector620(step D11). As shown inFIG. 16A, signal a has 10 and 100% amplification modulation degrees.

In detector circuit620, carrier extractor621outputs signal b synchronized in phase with the carrier wave of signal a. Multiplier622aof signal reproduction circuit622multiplies signal a by signal b, and outputs a resulting signal c. LPF622bfilters out high frequency components of signal c and as shown inFIG. 16C, outputs signal c1corresponding substantially to a base band signal of signal a (step D12).

Then, inverting amplifier618aof AGC circuit618inverts and amplifies signal c1and outputs a resulting signal d (step D13). Then, multiplier618bmultiplies signal a by signal d and outputs a resulting signal e (step D14). As shown inFIG. 16E, signal e has a substantially constant amplitude substantially equal to a maximum one of signal a although signal e is shown in a reduced size.

Then, AGC detector618cdetects signal e (for example, at its peak), outputs a resulting signal to LPF618d, which filters out high frequency components of detected signal e and outputs a resulting signal to AGC voltage generator618e(step D15).

Then, AGC voltage generator618egenerates RF and IF control signals f1and f2that control the amplification factors of RF and IF amplifiers611and616, respectively, in accordance with a level of the received signal thereof (step D16).

As described above, radio-wave reception circuit60multiplies intermediate frequency signal a by an inverted version d of signal c1(substantially equal to, more specifically, signal g) reproduced by signal reproduction circuit622, or modulates signal a with signal c1, thereby generating RF and IF control signals f1and f2that control the amplification factors of RF and IF amplifiers611and616, respectively, in accordance with a level of modulated signal e. Thus, AGC detector618cidealistically detects signal e having only intermediate frequency components. Thus, no filter having a time constant larger than the cycle of the received amplitude modulation signal need be provided to perform the AGC operation, thereby achieving high-speed AGC operation irrespective of the cycle of the amplitude modulation signal.

As described above, radio-wave reception circuit60adjusts the reception gain using the high-speed AGC operation immediately after the standard radio waves starts to be received, thereby outputting the appropriate frequency signal to time code generator70. Time code generator70generates a standard time code having a format ofFIG. 17based on the electric signal outputted from radio-wave reception circuit60and then provides it to CPU10. Thus, a time lag extending from the start of the radio wave generation to generation of the time code is greatly reduced.

Time counter80counts clock signals outputted from oscillator90and outputs the counted clock signals as internal time data to CPU10. Oscillator90, composed of a crystal oscillator, outputs clock signals of a fixed frequency to time counter80.

The limit error correction process to be performed in timepiece1will be described with reference to a flowchart ofFIG. 18. CPU10continuously at all times reads and executes a limit error correction process program41stored in ROM40A.

CPU10monitors whether the internal time data represents a reception start date (step E2). If so (Yes in step E2), CPU10controls radio-wave reception circuit60so as to start to receive the standard radio wave (step E4). The radio wave received by radio-wave reception circuit60is outputted to time code generator70, as required. Time code generator70generates a time code based on the received radio wave and then outputs it to CPU10(step E6).

When CPU10determines that a P signal included in the received time code has been detected (Yes in step E8), and then detects a next pulse as an M signal (Yes in step E10), CPU10causes time counter80to correct a “second” part of the internal time data to “01” when the next pulse has risen (step E12). When no pulse has been detected as an M signal immediately after the P signal has been detected (No in step E10) and the “second” part of the internal time data is “01” (Yes in step E14), CPU10determines that there is no error involved. On the other hand, when the “second” part is not “01” (No in step E14), CPU10determines that the internal time data has a slow error. In order to correct this error, CPU10responds to a rising edge of a next pulse to control time counter80so as to correct the “second” part of the internal time data to “11” (step E16). After correcting the error, CPU10controls radio-wave reception circuit60so as to terminate the reception of the standard radio wave rapidly (step E18).

Then, CPU10performs a reception start date calculation process (step E20), thereby calculating a new reception start date and updating reception start date data51stored in RAM50A.

Referring to a flowchart ofFIG. 19, this process will be described in more detail. First, CPU10reads from ROM50A previous reception start date51aand reception start date51b(indicative of the date when the reception of the radio wave was started this time) of reception start date data51and calculates a difference R1between these dates (step F22). Then, CPU10reads time correction quantity data52from RAM50A, divides R1by data52, and multiplies a resulting value by an absolute value of a limit error (in the present embodiment, ±8), thereby providing a resulting product R2(step F24). This implies that a time required for one second of an error to occur in timepiece1is calculated based on the error that has occurred in timepiece1from the previous reception of the standard radio wave to the reception of the standard radio wave effected this time, and then that a time required for the error in timepiece1to arrive at the limit error is calculated on assumption that a next error will occur at this calculated rate.

CPU10then overwrites previous reception start date51aof reception start date data51stored in RAM50A with reception start date data51bwhen the reception of the radio wave was started this time (step F26). Then, CPU10adds calculated R2to expected reception start date51band updates reception start date data51bof reception start date data51stored in RAM50A with the resulting data (step F28).

Now, referring toFIGS. 12A and 12B, a specified example of the reception start date calculating process will be described.FIGS. 12A and 12Bindicate start dates of nth and (n+1)th receptions, respectively, of the standard radio-wave. That is, reception start date data51ofFIG. 12Bis obtained by updating corresponding data51ofFIG. 12A. Now, it is assumed that the internal time was adjusted by a time correction quantity of 6 seconds so as to coincide with the time of the nth received standard radio wave. In this case, a next expected reception start date51bcalculated in the reception start date calculating process is “14 Oct., 2005 16:0:00”, as shown inFIG. 12B. This estimated date is obtained by subtracting previous-reception start date51a“26 Sep., 2004 00:0:00” represented by reception start date data51ofFIG. 12Afrom reception start date51b4 Oct., 2004 00:00:00” when the reception of the radio wave was started this time, thereby providing a difference of 8 days, which is then divided by time correction quantity of 6 (seconds), thereby providing one day and 8 hours. This time including one day and 8 hours is then multiplied by 8, which is an absolute value of the limit error, thereby providing 10 days and 16 hours. Then, the time of 10 days and 16 hours is added to reception start date51b“4 Oct., 2004 00:00:00” represented by reception start date data51ofFIG. 12A, thereby providing expected reception start date51b“14 Oct., 2004 16:0:00” ofFIG. 12B.

In summary, the present time-counting accuracy of timepiece1is calculated based on the time elapsed from previous reception start date51ato reception start date51bwhen the reception of the radio wave was started this time, and time correction quantity52used this time. Then, a time when an error occurring under this time-counting accuracy arrives at 8 seconds, which is the limit error, is estimated. Then, a next reception start date51bis calculated, which is a time when the standard radio wave should be received next, thereby correcting the error involving the internal time of timepiece1. Thus, since the error involving the internal time is always within an allowable range, radio-wave reception circuit60is caused to receive the radio wave for a minimum required time in the limit error correction process, thereby correcting an error involving the “second” part of the internal time automatically and hence maintaining an accurate internal time at all times.

When the reception start date calculating process ends, CPU10again performs the reception start date calculating process without terminating the limit error correcting process, thereby reopening monitoring whether the internal time data represents reception start date51a.

As described above, in accordance with timepiece1of the present embodiment, a time when an occurring error arrives at the limit error is estimated, thereby providing a date when the error should be corrected. When the time has come, the standard radio wave is received and then the error is corrected. In timepiece1, these steps are executed, thereby providing a minimum-time receiving operation automatically at the time when the error should be corrected without performing useless reception. Therefore, compared with the prior art timepiece, the reception time and hence the power consumption are greatly reduced.

Fifth Embodiment

FIG. 20is a block diagram of a fifth embodiment of a radio-wave timepiece2.

Referring toFIG. 20, timepiece2of the present embodiment is obtained by replacing ROM40A and RAM50A of the fourth embodiment with ROM40B and RAM50B, respectively.

Like ROM40A, ROM40B has stored an internal time reference correction process program42and a first to-be-corrected object specifying table program43in addition to other programs and data.

CPU10performs an internal time reference correction process based on corresponding program42, thereby receiving a part of one frame of a time code of the standard radio wave and correcting the corresponding internal time being counted by time counter80. Parts of the internal time data to be corrected are prescribed on first to-be-corrected object specifying table43.

As shown in the time code format of the standard radio wave ofFIG. 1, one frame comprises date data involving “minutes”, “o'clock”, and “day of the year” divided in units of a second and disposed in respective specified parts thereof. Thus, when only a part of the time code corresponding to a part of the internal time to be corrected is received in the internal-time reference correcting process, the “second” part of the internal time data must coincide accurately with that of the time code of the standard radio wave. Thus, immediately before the part of the time code corresponding to that of the internal time data to be corrected is received, an M signal included in the time code should be detected and the “second” part of the internal time data should be corrected to “00”. After this correction, only the part of the time code corresponding to that of the internal time data to be corrected is received based on first to-be-corrected object specifying table43.

FIG. 21illustrates first to-be-corrected object specifying table43. As shown, table43comprises execution day data43a, to-be-corrected object data43band acquire-location data43c. For example, when execution day43ais set to “1 Oct., 2004”, part of the internal time data (or object) to be corrected is determined to be “o'clock” data in accordance with to-be-corrected object specifying data43b. Acquire location43cfor the “o'clock” data is “12-19”, which indicates a “12th-19th” second location of the time code of the standard radio wave ofFIG. 1to be acquired to correct the “o'clock” data. Thus, “o'clock” data as to-be-corrected object data43bfor “Jan. 10, 2004” of execution day43ashould be acquired from the 12th-19th second location of the time code.

Like RAM50A, RAM50B has stored or stores various programs and data involving execution of these programs. As shown inFIG. 20, RAM50B has stored first to-be-corrected object reception command data53. As shown inFIG. 22, data53has a similar structure to first to-be-corrected object specifying table43. This is because first to-be-corrected object specifying table43is searched for an execution day closest to the day when the standard radio wave was received and command data corresponding to the appropriate execution day43ais read from first to-be-corrected object specifying table43and written as first to-be-corrected object reception command data53into RAM50B. Note that execution date53acomprises execution date43aappearing on first to-be-corrected object specifying table43plus a time when the internal time reference correcting process is executed. While the time data is illustrated as “02:00 a.m.”, the present invention is not limited to this particular time data, but any other appropriate time may be specified.

The internal time reference correction process of timepiece2will be described in detail with reference to a flowchart ofFIG. 23. CPU10executes internal time reference correction program42stored in ROM40B, thereby starting the corresponding process ofFIG. 23.

CPU10always monitors whether the internal time being counted by time counter80has arrived at execution date53aindicated by first to-be-corrected object reception command data53(step G2). If so (Yes in step G2), CPU10controls radio-wave reception circuit60to start to receive the standard radio wave (step G4). A signal indicative of the received standard radio wave is outputted to time code generator70, as required. Time code generator70generates a time code based on the received signal and outputs it to CPU10. CPU10detects an M signal from the signal received from time code generator70, and then corrects a “second” part of the internal time data to “00” (step G6). Immediately after the M signal has been detected, CPU10temporarily terminates reception of the standard radio wave by radio-wave reception circuit60(step G8).

CPU10monitors whether the “second” part of the internal time data has arrived at a time of seconds indicated in an acquire location53cin first to-be-corrected object reception command data53(step G10) If so (Yes in step G10), CPU10causes radio-wave reception circuit60to start to receive the standard radio wave and then terminates the reception of the radio wave at a time of “seconds” indicated in acquire location53c(step G12). A signal indicative of the standard radio wave received by reception circuit60is outputted to time code generator70as required. Time code generator70generates a time code from the signal received as required and then outputs it to CPU10(step G14). CPU10then causes time counter80to correct the internal time data based on the time code received from time code generator70(step G16). As shown inFIG. 22, the reception of the time code starts at a 12th second location and ends at a 19th second location, and only “o'clock” data of the internal time data is corrected based on this received time code.

Then, CPU10determines a day nearest and after the day when the internal time data was corrected this time based on first to-be-corrected specifying table43(step G18), reads from table43command data corresponding to determined execution day43aand writes it as first to-be-corrected object reception command data53to RAM50B for updating purposes (step G20). The day nearest and after execution day date53a“January 4, 02:00 a.m.” is “every Sunday” inFIGS. 21 and 22. If that execution date53ais Monday, a new execution date53ais determined to be “July 4, 02:00 a.m.”. CPU10then reopens to monitor whether the internal time data has arrived at new execution date53awithout terminating the internal time reference correction process.

As described above, according to timepiece2of the present embodiment, only a part of the internal time data predetermined on first to-be-corrected object specifying table43is corrected based on a date predetermined on the table. In order to receive a required part of one frame of the time code corresponding to the “second” part of the internal time data, the “second” part of the internal time is monitored and the timepiece waits starting to receive the standard radio wave until immediately before the required part of the time code appears. Thus, useless reception is eliminated greatly, and the reception time and hence the power consumption are greatly reduced compared with the prior art.

Sixth Embodiment

FIG. 24is a block diagram of a sixth embodiment of a radio-wave timepiece3. As shown inFIG. 24, timepiece3is obtained by replacing ROM40A and RAM50A of the fourth embodiment with a ROM40C and a RAM50C, respectively.

Like ROM40A, ROM40C has stored various programs and data. As shown inFIG. 24, ROM40C has stored a P signal reference correction program44to perform a corresponding process, and a second to-be-corrected object specifying table45that has stored data involving execution of the P signal reference correction process.

CPU10performs the P signal reference correction process, thereby correcting a part of the internal time data being counted by time counter80. The parts of the internal time data to be corrected are predetermined on second to-be-corrected object specifying table45.

FIG. 25illustrates second to-be-corrected object specifying table45. Referring toFIG. 25, table45comprises execution day data45a, to-be-corrected object data45b, acquire location data45c, P signal start count data45dand P signal end count data45e. The P signal reference correction process of the present embodiment comprises acquiring a part of the received time code corresponding to to-be-corrected object data45bof the internal time data based on the number of times the P signal included in the received time code was received and not based on the internal time being counted by time counter80, and then correcting object data45bwith that part of the time code. To this end, the start and end counts45dand45eof P signals which are not included on first to-be-corrected object specifying table43are additionally employed on table45.

Referring toFIG. 24, RAM50C has stored second to-be-corrected object reception command data54to cause the P signal reference correction process to be performed.

FIG. 26illustrates second to-be-corrected object reception command data54. InFIG. 26, data54is similar in structure to second to-be-corrected object specifying table45ofFIG. 25. This is because as in first to-be-corrected object reception command data53of the fifth embodiment, an execution day nearest and after the day when the error involving the internal time data was corrected is retrieved from second to-be-corrected object specifying table45, and then command data corresponding to the appropriate execution day45ais read from second to-be-corrected object specifying table45and written as second to-be-corrected object reception command data54into RAM50C. Note that execution data54acomprises data on an execution day45aspecified on second to-be-corrected object specifying table45and data on a time when the P signal reference correction process is executed. This time data represents a predetermined prescribed time and in the present embodiment, “2:00 a.m.”. However, the present invention is not limited to this specified time.

The P signal reference correction process to be performed in timepiece3will be described with reference to a flowchart ofFIG. 27. CPU10starts to perform the P signal reference correction process by executing the corresponding program44stored in ROM40C.

CPU10always monitors whether the internal time being counted by time counter80has arrived at execution date54aincluded in second to-be-corrected object reception command data54stored in RAM50C (step H2). If so (Yes in step H2), CPU10causes radio-wave reception circuit60to start to receive the standard radio wave (step H4). The received radio wave is inputted to time code generator70, as required. Generator70then generates a time code from the received signal and outputs it to CPU10. CPU10detects an M signal from the signal received from time code generator70(step H6) and monitors a time code received from time code generator70(step H8). CPU10counts the number of P signals detected and monitors whether it has arrived at the end count45eof P signals included in second to-be-corrected object reception command data54(step H10).

When CPU10determines that the number of times the P signal included in the received time code was detected has arrived at P signal end count45e(Yes in step H10), CPU10causes radio-wave reception circuit60to terminate reception of the radio wave (step H12). Then, CPU10causes time counter80to correct the internal time data based on an acquire location54cof the time code received from time code generator70(step H14). As shown inFIG. 26, only day of the year data of the internal time data is corrected based on the received time code. After detecting four P signals, which brings about the P signal end count, CPU10causes radio wave reception circuit60to terminate receiving the radio wave rapidly.

Then, CPU10determines, as a new execution day45a, a day nearest and after the day when the internal time was corrected this time on second to-be-corrected object specifying table45(step H16), reads command data corresponding to the determined execution day45afrom second to-be-corrected object specifying table45and writes it as new second to-be-corrected object reception command data54into RAM50C for updating purposes (step H18). Referring toFIGS. 25 and 26, for example, a day nearest and after execution date54a“January 3, 2:00 a.m.” among the execution days45ais “every Sunday”. If the execution date54ais Wednesday, new execution date54ais determined as “May 3, 2:00 a.m.”. Then, CPU10reopens monitoring whether the internal time data has arrived at new execution date54awithout terminating the P signal reference correction process.

As described above, according to timepiece3of the present embodiment, only a part of the internal time data predetermined on second to-be-corrected object specifying table45is corrected based on a corresponding date predetermined on table45. A required part of one frame of the time code corresponding to a time period ranging from detection of an M signal to counting the predetermined number of P signals in the time-code frame is received. Thus, the radio wave reception and the power consumption are greatly reduced compared with the prior art in which the whole frame of the time code is received.

Seventh Embodiment

FIG. 28is a block diagram of a radio-wave timepiece1of the seventh embodiment.

The radio-wave timepiece1of the seventh embodiment is obtained by replacing ROM40C and RAM50C of the sixth embodiment ofFIG. 7with ROM40aand RAM50aofFIG. 28, respectively.

When a predetermined time, for example, of 2 o'clock a.m. or a predetermined time zone has come, CPU10starts to perform a first time correction process to be described later in detail, controls reception circuit60to receive the standard radio wave, and corrects present-time data81stored in RAM50acounted by time counter80based on the standard time code received from time code generator70. CPU10also outputs a display signal based on present-time data81to display30, thereby updating the display time.

ROM40ahas stored various initial set values, initial programs, and other programs to perform various functions of timepiece1, and data. It also has stored, especially, a first time correction program41to realize the corresponding process.

ROM50astores various programs to be executed by CPU10, data involving execution of these programs, and has also stored reception time code data51and saved time code data52which are variables in the first time correction process.

These variables (hereinafter referred to as time code variables) in RAM50ahave the time code format ofFIG. 1. As will be described later, in RAM50aCPU10stores a standard time code outputted from time code generator70as received time code data51, partially edits data51as required, or copies saved time code data52to RAM50a.

A time part between nth and (n+1)th “seconds” in the time code variable will be referred hereinafter as an nth “second” location. A 0th “second” location where a head marker M, or an M signal, is present will be hereinafter referred to as an M signal location. In addition, 9th, 19th 29th, 39th, 49th and 59th “second” locations where P signals are present can be hereinafter referred to as P signal locations.

Radio-wave reception circuit60performs reception of the standard radio waves that includes picking up only a frequency signal corresponding to a standard radio wave from among radio waves received at an antenna ANT, converting this signal to another corresponding signal, and then outputting it to a time code generator70. Time code generator70produces a standard time code in a format shown inFIG. 1based on the signal from reception control unit60, and then outputs it to CPU10.

Time counter80counts clock pulses of a fixed frequency from oscillator82, thereby holding present-time data81, which is then outputted to CPU10. Present-time data81is corrected by CPU10in a predetermined process.

A first time-correction process to be performed in the radio wave timepiece1will be described in detail with reference to a flowchart ofFIG. 29. When the time indicated by present-time data81arrives at 2 o'clock a.m., CPU10of radio wave timepiece1reads first time-correction program41stored in ROM40aand executes that program, thereby starting the first time-correction process ofFIG. 29.

First, CPU10causes reception circuit60to receive the standard radio wave (step I11). Then, CPU10controls time code generator70so as to generate a standard time code, and then stores it as received time code data51in RAM501(step I13).

Next, CPU10searches the standard time code51for any lacks (step I15). Then, CPU10determines whether the lacks are only at the locations of the P signals in received time code data51(step I17).

When CPU10determines that there are no lacks in the P signal locations at step I17, CPU10further determines whether the standard radio wave has any lack in other signals excluding the P signals. If so (No in step117), CPU10further determines whether any lacks were detected in 0th-to-49th-second locations of the standard radio wave (step I19).

If not (No in step I19), CPU10further determines whether any lacks were detected in 50th-59th-second locations of code data51(step I21).

If not (No in step I21), CPU10corrects present-time data81using received time code data51, thereby terminating this process (step I39). This process was performed when there were no lacks in the standard time code generated based on the standard radio wave received at step I11. In this case, CPU10corrects preset-time data81using received time code data51of the same content as the generated standard time code.

When in step I21CPU10detects that lack of time code element data in 50th-59th “second” locations of received time code data51(Yes in step I21), CPU10fills up the lack with appropriate time code element data in 20th-49th “second” locations of time code data51(step I27). More specifically, CPU10obtains a day of the week using values indicative of the day of the present year and the present year stored in 20th-49th “second” locations where no data are lacking. Then, the time code is edited such that the lack in the 50th-59th “second” locations is filled up with a value, which is one of 0-6, indicative of the day of the week thus obtained.

Then, CPU10corrects present-time data81using this edited received time code data51, thereby terminating this process (step I39). That is, even when the code element of the standard time code is lacking in the 50th-59th second locations, time correction is achieved normally without receiving the standard radio waves again.

When in step I17CPU10determines that only a P signal is lacking at its original location in the time code data51(Yes in step I17), CPU10fills up the lack with data on another P signal in a location other than in the lack position (step I29). As shown inFIG. 1, the P signals are disposed at intervals of 10 seconds in time code data51. Thus, the lack can be filled up with data on an adjacent complete P signal. For example, when a lack of a P signal P2(seeFIG. 1) is detected in a 19th “second” location, it can be filled up with data on a P signal P3present in a 29th “second” location.

Then, CPU10corrects present-time data81using this complemented time code data51, thereby terminating this process (139). That is, even when a P signal is lacking in its original location in the standard time code obtained from the received standard radio wave, time correction is normally achieved without receiving the radio wave again. Also, this applies similarly when time code element data in the 50th-59th “second” location of the standard time code are lacking.

When CPU10detects that a time code element is lacking in a 0th-49th second locations of time code data51(Yes in step I19), CPU10first determines whether the reception of the standard radio wave performed this time in step I11was for the first time (step I31).

If so (Yes in step I31), CPU10copies received time code data51to a location for saved time code data52, thereby saving the standard time code obtained this time (step I33), and then goes to step I11.

Then, CPU10again performs the first time correction process. That is, CPU10receives the standard radio wave again (step I11) and then performs time correction process (steps I13-I39) using the generated standard time code (steps I13-I39).

If in this case there is no lack in the generated standard time code, CPU10completes present-time data81with received time code data51having the same content as the generated standard time code. Even when there is a lack in the generated standard time code, time correction can be normally achieved without receiving a further standard radio wave when a P signal and a time code element in the 50th-59th second locations are lacking.

When CPU10detects that there is lack of a time code element in the 0th-49th second locations of the standard time code and hence of time code data51, generated from the again received radio wave (steps I11-I15→ No in step I17→ Yes in step I19→ No in step I31), CPU10determines whether time code data51can be replaced with saved time code data52that comprises the standard time code data received first (step I35).

When, for example, two time code variables have no lacks of common code elements in corresponding 0th-49th second locations, they can be determined as replaceable with each other, and if not, they are determined as unreplaceable.

When received time code data51is replaceable with saved time code data52(Yes in step I35), CPU10replaces time code data51with saved time code data52(step I37). More specifically, CPU10specifies the location of a lack in received time code data51and then overwrites it with corresponding data part of saved time code data52.

Thus, even when there are lacks in 0th-49th locations in the standard time code obtained from the standard radio wave and the standard radio wave need be received again, normal time correction is achieved by receiving the radio wave a smaller number of times than in the prior art.

Thus, according to radio wave timepiece1of the present embodiment, the time and hence power consumption required for receiving the standard radio wave are greatly reduced.

While in the above embodiment when P signal data is found to be lacking in its location in the received time code the lack is illustrated as filled up with a normal P signal in another location, the present invention is not limited to this particular case. For example, when a lack of a P signal (for example, P1inFIG. 1) in its (for example, 9th second) location is detected, it may be filled up with an M signal disposed at the head location of the received time code.

Eighth Embodiment

FIG. 30is a block diagram of a radio-wave timepiece2of the eighth embodiment. As shown inFIG. 30, timepiece2is obtained by replacing ROM40aand RAM50aof the seventh embodiment with ROM40band RAM50b, respectively. Time counter80of timepiece2has the same structure as that of the seventh embodiment and counts time in present-time data81, which will be described below in more detail.

FIG. 31schematically illustrates the content of present-time data81saved by time counter80. As shown inFIG. 31, present-time data81comprises calendar year data81a(represented by the last two digits of the present year in AD), day-of-the-year data81b, o'clock data81c, minute data81d, second data81e, and day-of-the-week data81f(represented by a respective one of 0-6) stored in a BCD notation. For example,FIG. 31illustrates Nov. 1, 2004, Monday, “2 (o'clock):00 (minutes):00 (seconds)” indicated in a decimal notation for simplifying purposes. Reference characters81g,81hand81jdenote the unit digits of year, o'clock, and minute data81a,81cand811d, respectively.

ROM40b, similar to ROM40a, has stored programs and data, especially a second time-correction program42and an acquire-location specifying table43that will be described later in more detail.

As shown inFIG. 32, acquire-location specifying table43comprises execution day data indicative of a day when data correction is to be corrected, to-be-corrected data indicative of part of present-time data81to be corrected, and acquire location data representing a location in the standard time code where data to be corrected should be acquired. Each of the acquire-location data should include a P-signal location.

RAM50b, similar to RAM40a, stores various programs and data involving the execution of the respective programs, and especially partial time code data54, to-be-corrected data55, acquire-location data56, reception period data57and time-counting correction data58that are variables in the second time correction process.

Partial time code data54is a part of the time code produced by receiving the standard radio wave in the second time correction process, and is also a time code variable like received time code data51.

To-be-corrected data55, shown in the acquired-location specifying table ofFIG. 32, is a variable representing part of present-time data81to be corrected in the second time correction process. Acquire-location data56, as shown inFIG. 32, represents a location where the to-be-corrected code data is to be acquired in the standard time code.

Reception period data57represents a period delimited by reception start and end times for which period the standard radio wave should be received. Time counting correction data58is used to overwrite present-time data81.

A time correction process that corrects the time indicated by radio wave timepiece2will be described with reference to flowchart ofFIG. 33.

CPU10performs time correction program42stored in ROM40b, thereby starting the time correction. CPU10waits until the time counted in present-time data81arrives at 2:00 a.m. (Yes in step J11), at which time CPU10determines part of present-time data81to be corrected based on acquire-location specifying table43and the present date and day of the week of present-time data81, and then stores it as to-be-corrected data55in RAM50b(step J13).

In this case, CPU10first obtains the present date and the present day of the week from day-of-the year data81band day-of-the week data81f, respectively, of present-time data81. CPU10then specifies to-be-corrected data corresponding to the obtained present date and day of the week on table43, and then stores these data as to-be-corrected data55. For example, with November, 1 (Monday) shown inFIG. 31, CPU10stores in RAM50bdata on the unit digit of o'clock for a “first day of each month” in the “execution day” column ofFIG. 32as to-be-corrected data55.

Then, CPU10specifies an acquire-location corresponding to the to-be-corrected data on acquire-location specifying table43, and then stores it as acquire-location data56(step B15). For example, if to-be-corrected data55is the unit digit of “o'clock”, corresponding “15th-19th second locations are stored as acquire-location data56.

Then, CPU10determines times when the reception of the standard radio wave starts and ends based on the acquire-location data56by allowing for a time counting error concerned, and then stores data on a reception period57delimited by the start and end times (step J17).

In this case, CPU10calculates an error time involving the internal time of timepiece2in this time correction process based on an error time per month determined from the specifications of time counter80and oscillator82, and a time elapsed since the previous time correction. For example, when one day has elapsed since the previous time correction with a time error within ±30 seconds per month, the error time involving the present internal time is calculated as 1 second. That is, the time represented by present-time data81is a maximum of 1 second fast or slow compared with the correct time.

CPU10then determines the times when the reception of the standard radio wave starts and ends based on acquire-location data56by allowing for the error time. For example, when acquire-location data56is between 15th and 19th seconds and the error time is 1 second, CPU10determines that the reception of the standard radio waves should start at 2:0:14 a.m. and end at 2:00:20 a.m. such that part of the time code data in the 15th-19th second locations on the standard radio wave for 2:00 a.m. can be acquired.

Then, CPU10waits until the time when the reception of reception period data57starts (Yes in step J19), at which time CPU10starts to receive the standard radio wave (step J21). CPU10then continues to receive the radio wave until the time when the reception of data57ends (Yes in step J23), at which time CPU10then terminates the reception of the standard radio wave (step J25). That is, the standard radio waves are received, for example, for 6 seconds from 2:00:14 a.m. to 2:00:20 a.m.

Then, CPU10generates a standard time code from the received standard radio wave and then stores it as partial time code data54in RAM54(step J27). The partial time code data54comprises the time code data in 14th-19th second locations on the standard time code. In this respect, the time represented by present-time data81is one second fast compared with the standard time.

In this case, CPU10can recognize that partial time code data54is data in 14th-19th second locations by considering the fact that the P signal is in the 19th second location.

Then, CPU10extracts acquire-location data56of partial time code data54stored in RAM50band then stores it as time counting correction data58in RAM50b(step J29). For example, a numeral “2” indicative of unit digit of o'clock data in 14th-19th second locations of time code data54stored in RAM50bis extracted and then stored as time-counting correction data58in RAM50b.

As described above, in accordance with this process and hence timepiece2of the present embodiment, the standard radio wave is received in a very short time such as 6 seconds compared with the period of the time code, the time is corrected based on the received standard radio wave, and power consumption is reduced.

Advantages Produced by the Embodiments

In one embodiment, a time information receiver (for example, radio wave timepiece1inFIG. 28) comprises:

receiving means (for example, radio wave reception circuit60inFIG. 28; step I11inFIG. 29) for receiving a standard radio wave;

first controlling means (for example, CPU10inFIG. 28; step I13inFIG. 29) for controlling the receiving means to receive the standard radio wave, thereby acquiring a time code from the radio wave;

detecting means (for example, CPU10inFIG. 28; steps I15, I19in step ofFIG. 29) for detecting a lack of o'clock and minute data included in the time code acquired under control of the first controlling means;

second controlling means (for example, CPU10inFIG. 28; steps I19, I31, I33, I35, I37in step ofFIG. 29), responsive to the detecting means detecting the lack of o'clock and minute data included in the time code, for

controlling the receiving means to receive the standard radio wave again, thereby acquiring a new time code from the radio wave, and for filling up the lack of o'clock and minute data in the time code acquired under control of the first controlling means based on the acquired new time code; and

correcting means (for example, CPU10inFIG. 28; step I39ofFIG. 29) for correcting the time being counted by the time counting means with the filled up time code.

According to the present embodiment, the standard radio wave is received, and thereby the time code is acquired from the radio wave. When a lack of the o'clock and minute data included in the time code element data is detected, the standard radio wave is received again, and then a new time code is acquired. Then, the lack of the o'clock and minute is filled up based on the first-mentioned and new time code data. The time being counted by the time counting means is then corrected with the time code whose lack was filled up.

Thus, when a lack of the o'clock and minute data included in the acquired time code data is detected, the standard radio wave need be received only once more to correct the time being counted by the time counting means. Accordingly, a time information apparatus is provided in which the time required for receiving the standard radio wave and its power consumption are minimized.

In one embodiment, a time information receiver (for example, radio wave timepiece1inFIG. 28) comprises:

counting means (for example, time counter80inFIG. 29) for counting time which has a part involving a day of the week;

receiving means (for example, radio wave reception circuit60inFIG. 28; step I11inFIG. 29) for receiving a standard radio wave;

controlling means (for example, CPU10inFIG. 28; step I13inFIG. 29) for controlling the receiving means to receive the standard radio wave, thereby acquiring a time code from the radio wave;

detecting means (for example, CPU10inFIG. 28; steps I15, I21inFIG. 29) for detecting a lack of day of the week data included in the acquired time code;

filling-up means (for example, CPU10inFIG. 28; steps I21, I27inFIG. 29), responsive to the detecting means detecting the lack of day of the week data, for filling up the lack of day of the week data based on year data and day of the year data included in the acquired time code; and

correcting means (for example, CPU10inFIG. 28; step I39inFIG. 29) for correcting the time being counted by the time counting means with the time code whose lack of day of the week data was filled up by the filling-up means.

According to the present embodiment, the standard radio wave is received, and the time code is thereby acquired from the radio wave. When a lack of the day of the week data included in the time code element data is detected, the lack is filled up based on the year and day of the year data included in the time code. The time being counted by the time counting means is then corrected with the time code whose lack was filled up.

Thus, when such lack is detected, the time being counted by the time counting means can be corrected without receiving the standard radio wave again. Accordingly, a time information apparatus is provided in which the time required for receiving the standard radio wave and its power consumption are minimized.

In one embodiment, a time information receiver (for example, radio wave timepiece1inFIG. 28) comprises:

receiving means (for example, radio wave reception circuit60inFIG. 28; step I11inFIG. 29) for receiving a standard radio wave;

controlling means (for example, CPU10inFIG. 28; step I13inFIG. 29) for controlling the receiving means to receive the standard radio wave, thereby acquiring a time code from the radio wave;

detecting means (for example, CPU10inFIG. 28; steps I15, I17inFIG. 29) for detecting a lack of a particular one of a plurality of identification data disposed at predetermined intervals of time in the acquired time code according to a standard of the standard radio wave;

filling-up means (for example, CPU10inFIG. 28; step I29in step ofFIG. 29), responsive to the detecting means detecting the lack of the particular item of identification data, for filling up the lack of the particular item of identification data based on another one of the plurality of items of identification data and the predetermined intervals of time included in the acquired time code; and

correcting means (for example, CPU10inFIG. 28; step I39inFIG. 29) for correcting the time being counted by the time counting means with the time code whose lack of the particular item of identification data was filled up by the filling-up means.

According to the present invention, the standard radio wave is received, and thereby the time code is acquired from the radio wave. When a lack of a particular one of a plurality of items of identification data inserted at predetermined intervals of time in the acquired time code according to the standard of the standard radio wave is detected, the lack is filled up based on the other items of identification data and the predetermined intervals of time included in the acquired time code. The time being counted by the time counting means is then corrected with the time code whose lack is filled up.

Thus, when such lack is detected, the time being counted by the time counting means can be corrected without receiving the standard radio wave again. Accordingly, a time information apparatus is provided in which the time required for receiving the standard radio wave and its power consumption are minimized.

In one embodiment, a time information receiver (for example, radio wave timepiece1inFIG. 28) comprises:

counting means for counting time (for example, time counter80inFIG. 28);

receiving means for receiving a standard radio wave (radio wave reception circuit60inFIG. 28; step I11inFIG. 29);

controlling means (for example, CPU10inFIG. 28; step I13inFIG. 29) for controlling the receiving means to receive the standard radio wave, thereby acquiring a time code from the radio wave;

detecting means (for example, CPU10inFIG. 28; steps I15, I17ofFIG. 29) for detecting a lack of a particular one of a plurality of items of identification data inserted at predetermined intervals of time according to a standard of the standard radio wave in the acquired time code, the particular item of identification being adjacent to head data of the time code;

filling-up means, responsive to the detecting means detecting the lack of the particular item of identification data, for filling up the lack of the particular item of identification data based on head data of the time code; and

correcting means (for example, CPU10inFIG. 28; step I39inFIG. 29) for correcting the time being counted by the time counting means with the time code whose lack of the particular item of identification was filled by the filling-up means.

According to the present embodiment, the standard radio wave is received, and thereby the time code is acquired from the radio wave. When a lack of a particular one of a plurality of items of identification data inserted at predetermined intervals of time in the acquired time code according to the standard of the standard radio wave is detected, the particular item of identification data being adjacent to the head data of the time code, the lack is filled up based on the head data of the time code. The time being counted by the time counting means is then corrected with the time code whose lack is filled up. The time being counted by the time counting means is then corrected with the time code whose lack was filled up.

Thus, when such lack is detected, the lack can be filled up and the time being counted by the time counting means can then be corrected without receiving the standard radio wave again. Accordingly, a time information apparatus is provided in which the time required for receiving the standard radio wave and its power consumption are minimized.

In one embodiment, a time information receiver comprises:

counting means (time counter80inFIG. 28) for counting time which has a part involving o'clock, minutes and seconds;

receiving means (radio-wave reception circuit60inFIG. 28) for receiving a standard radio wave including a time code, thereby acquiring the time code;

detecting means (CPU10inFIG. 28; steps I15, I17inFIG. 29) for detecting a lack of a particular one of a plurality of items of identification data disposed in the acquired time code according to a standard of the standard radio wave, the particular item of identification data being adjacent to head data of the time code;

filling-up means (CPU10inFIG. 28; step I29inFIG. 29), responsive to the detecting means detecting the lack of the particular item of identification data, for filling up the lack of the particular item of identification data with corresponding head data part of a time code acquired beforehand by the receiving means; and

correcting means (CPU10inFIG. 28; step I39inFIG. 29) for correcting the time being counted by the counting means based on the time code whose lack of the particular item of identification data was filled up by the filling-up means.

According to the present embodiment, when a lack of a particular one of a plurality of items of identification data disposed in the acquired time code according to the standard of the standard radio wave is detected, the particular item of identification data being adjacent to head data of the time code, the lack is filled up with part of a time code acquired beforehand by the acquiring means corresponding to the head data of the time code. Then, the time being counted by the time counting means is corrected rapidly and securely based on the time code whose lack was filled up. Accordingly, a time information apparatus is provided in which the time required for receiving the standard radio wave and its power consumption are minimized.

Various modifications and changes may be made thereto without departing from the broad spirit and scope of this invention. The above-described embodiments are intended to illustrate the present invention, not to limit the scope of the present invention. The scope of the present invention is shown by the attached claims rather than the embodiments. Various modifications made within the meaning of an equivalent of the claims of the invention and within the claims are to be regarded to be in the scope of the present invention.