JPH08101288A - Time measuring system and clock - Google Patents

Abstract

PURPOSE: To enhance accuracy in the measurement of time by opening a gate at a timing common to a plurality of power supply frequencies and counting only one wave number thereby preventing miss counting due to noise. CONSTITUTION: The power supply frequency waveform of 50/60Hz from an AC power supply A is shaped through a shaper circuit 1 and fed to one input terminal (a) of an AND gate 2 having the other input terminal 2b being fed with a control signal for opening the gate 2 for a predetermined time from a control circuit 4. Output from the AND gate 2 is counted by a counter circuit 3 and presented on a display 8. The control circuit 4 includes a memory 5 which stores a count for presetting a predetermined delay value, e.g. a gate release time 16.67ms or a measurement disable delay 83.33ms, and the count thus stored is fed through a counter 6 to the input terminal 2b of the gate 2. The counter 6 receives a clock from a quartz oscillator in an oscillation circuit 7 and loads the clock through the control circuit 4 to the input terminal 2b of the gate. This constitution can correct the time measured upon instantaneous power interruption at the cost of accuracy.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a home electric appliance for counting a power wave number to realize a highly accurate timepiece.

[0002]

2. Description of the Related Art Conventionally, when a clock with a difference of 5 seconds or less is needed, it is impossible to obtain such accuracy even if a crystal oscillator is used. Therefore, a clock should be constructed by measuring a commercial AC power waveform. Has been done. AC along with fluctuations in power demand
The power supply frequency also fluctuates, but the power company controls and manages the generator so that the integrated value of the difference from 50 Hz / 60 Hz becomes 0. If you count the AC power supply wave number and measure the time, the error Does not accumulate.

On the other hand, commercial AC power supplies are 50 Hz and 60 Hz.
There are two types. If you do not know which frequency it is, you cannot measure time. For this reason, there is a device in which the user sets the supplied power frequency by using the changeover switch. It is troublesome for a user to set the power supply frequency, and a setting error is likely to occur, so that the power supply frequency is often automatically determined. Conventionally,
The automatic determination of the power supply frequency is performed by counting the number of power supply waves within a fixed time after the AC power supply is turned on.

[0004]

Since the power supply frequency is automatically determined, it is not easy to count the number of power supply waves within a fixed time after the AC power supply is turned on. Such power-on operation is
It is to point the outlet into the plug, and excessively,
This is because the power supply is intermittently connected many times.
If the AC50 or 60 Hz determination is erroneous, an error of about 20% occurs in the time measurement, so it is necessary to prevent erroneous determination. For this reason, a method of making the number of determinations plural times has been used.

It is complicated to repeatedly determine the AC power supply frequency. Further, performing the determination a plurality of times only lowers the probability of erroneous determination, and the risk of erroneous frequency determination remains. As described above, the present invention enables time measurement by counting the number of power source waves without making a complicated and uncertain determination of the AC power source frequency. Moreover, simply counting the number of power supply waves also counts the noise mixed in the power supply. As a result, there is a problem that the time counted becomes long and the clock is delayed due to the corrected counting result. Commercial power sources may experience a momentary power failure due to a lightning strike. When this occurs, the time measured is reduced, and there is a problem that the clock advances due to the corrected counting result.

[0006]

According to the present invention, in a device that uses the constant frequency of an AC power supply to perform high-precision time measurement from the power supply frequency, the time is measured with accuracy using an internal oscillator as a signal source. Means, means for counting the AC power wave number for time measurement by checking the power supply waveform, and AC from the internal oscillator
It is a time measuring method that includes a means for obtaining a timing for permitting measurement of the power wave number for each integral multiple of a predetermined period synchronized with the power frequency and a means for counting and counting the power wave number for time measurement at the timing. .

Further, the present invention provides a device for performing highly accurate time measurement from the power supply frequency by utilizing the constant frequency of the AC power supply, a means for measuring time with accuracy using an internal oscillator as a signal source, and a power supply waveform. A means for counting the number of AC power supply waves for time measurement, a means for obtaining a timing for allowing the power supply wave number to be counted from the internal oscillator for each integral multiple of a predetermined period synchronized with the AC power supply frequency, and a time measurement at the timing. It is a timepiece equipped with a means for counting and counting the number of power supply waves for use in.

Further, the predetermined time period is N × 50 ms, where N is an integer, and the repetitive waveforms of a plurality of power supplies having different frequencies are counted at a common gate timing. Also, in a device that uses the constant frequency of the AC power supply to perform highly accurate time counting from the power supply frequency, a means for obtaining a clock signal with accuracy using the internal oscillator as a signal source, and a power supply waveform for time measurement Means for counting the number of AC power supply waves, means for obtaining a predetermined timing for permitting the presence or absence of repetition of the power supply wave number for each integral multiple of a predetermined period synchronized with the AC power supply frequency from the internal oscillator, and time for the timing. This is a time measuring method that is provided with a means for counting and counting the number of power source waves for measurement, and a means for correcting this when the count is missing or a large number is counted.

[0009]

According to the present invention, even when connected to a plurality of power supplies having different power supply frequencies, a predetermined width is provided and a gate is opened and counting is performed at a common waveform change timing. Even if the frequency is different, it is not necessary to switch clocks, etc., and the count value is configured to open the gate only for a predetermined period to prevent miscounting due to random noise such as internal and external switching noise. With the predictive correction means, stable counting operation can be performed for a long time and an accurate clock function can be obtained.

In the conventional waveform counting system, the number of power source waves is always counted and counted, but in the present invention, the counting timing is specified instead of always counting. As a result, the count value of the power wave number can be made to be the same regardless of whether the power frequency is 50 Hz or 60 Hz. That is, the gate is opened for a certain short time aiming at the timing when the phase with the power supply waveform is the same for both frequencies, the period during which the power supply wave number can be measured is set for a predetermined period, and the power supply wave number is counted only during that period. To do.

A more specific description will be given. 16.67 ms is set as a power source wave number countable period at a timing of 100 ms or an integral multiple thereof, and the power wave number is measured only during the 16.67 ms. By doing so, the same count value is obtained regardless of whether the power supply frequency is 50/60 Hz. However, the result of counting the wave number is 1 / (5 × N) or 1 / (6 × when all wave numbers are counted.
N) and N are natural numbers.

FIG. 2 shows that the same counting result can be obtained regardless of the power source of AC 50/60 Hz by counting every 100 ms or an integral multiple thereof. AC50
The elapsed time of 5 waves of Hz and the elapsed time of 6 waves of AC 60 Hz are the same 100 ms, and the phase shift between both waveforms is 10
It becomes the same in the 0 ms cycle. In other words, 1 second x 5 / 50Hz
= 1 second x 6 / 60Hz = 100ms, so 100ms
If the wave number is counted for each, the same counting result will be obtained for both frequencies of AC50 / 60. When using a double-wave rectified signal,
The same counting result is obtained if counting is performed every integer multiple of 50 ms.

This phase aligned 50 ms or 10
If the power wave number is counted only at the timing of an integral multiple of 0 ms, the time can be measured without detecting the power frequency of 50 Hz / 60 Hz. Further, the power wave number is counted only during the counting permission period, and the wave number is counted as only one. 2 due to noise
Even if the number of waves is entered, the count configuration is such that only one wave is counted. This makes it possible to eliminate the influence of noise on the power supply. When the power wave number cannot be counted during the power waveform countable period due to an instantaneous power failure, or when the power wave number countable period ends, a correction count pulse can be generated to correct the power wave count circuit. .

Instead of measuring all the power wave numbers, 10
By measuring the power wave number only at the timing of an integral multiple of 0 ms, it is possible to measure the same time regardless of the power frequency without detecting the power frequency: AC50 / 60 Hz. Further, even if noise occurs during the period other than the counting permission period, the number of waves is not counted during that period, so the influence can be reduced. Even if noise is added to the counting permission period, it is counted only once, so it is not affected by noise. When there is no power supply waveform signal to be counted during the counting permission period due to a momentary power failure or the like, it can be corrected.

[0015]

An embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram showing a waveform sampling position and its counting timing.
The power source frequency waveform of 50 Hz or 60 Hz from the AC power source A is shaped through the shaping circuit 1 and connected to the input a of the AND gate 2. A control signal for opening the gate for a predetermined short time is input to another input b of the AND gate 2. The output of the AND gate 2 is counted by the counting circuit 3 and is output to the display 8 for displaying the time, and the time is displayed.

The output of the AND gate 2 is also input to a control circuit 4 for controlling the entire apparatus, and the control circuit is capable of presetting a delay value for a predetermined period in a memory 5 which stores a delay value for timing the frequency counting. The value is stored, for example, the measurement prohibition delay value 91.67 ms,
The gate opening time value of 16.67 ms and the measurement prohibition delay value of 83.33 ms are stored, and the preset value is set to the counter 6 which presets the delay value.

The counter 6 obtains an accurate clock from the crystal oscillator from the oscillation circuit 7 that oscillates the reference clock, outputs a carry signal to the control circuit, and is loaded from the control circuit 4 to the input b of the AND gate 2. Therefore, the clock obtained from the oscillating circuit 7 serves as a basis for performing low-accuracy time measurement and also serves as a reference timing for moving the entire circuit.

The operation of counting the number of power supply waves every 100 ms will be described with reference to the timing charts of FIGS. 1 and 3. The control circuit 4 operates in the following order. 1) a: Operate the power wave number measurement prohibition delay of 91.67 ms at the timing (arbitrary zero cross point in the positive direction of the AC power supply). The power wave number is not counted while the delay is working.

2) b: When the delay of 91.67 ms is timed up, the countable delay of 16.67 ms is activated. The counting measurement is permitted so that the power wave number can be measured only once while this delay is working. 3) c: When the positive zero-cross point of the AC power source is detected during the count enable period in which counting is possible, the power wave number measurement prohibition delay of 91.67 ms is activated again. Then, the operation from 2) is repeated again.

4) d: When the positive zero-cross point of the AC power source cannot be detected during the counting permission period due to a momentary power failure or the like, wait for the countable delay time up and wait for the 83.33 ms power source. Activate the wave number measurement delay. At this time, the zero cross of the power source cannot be detected, but the correction count shown in g of FIG.
The pulse is output to the counting circuit 3, and the power wave number counting is increased by one. Then, the operation from 2) is repeated again.

Although the above embodiment permits counting every 100 ms, the same effect can be obtained by permitting counting every integer multiple of 100 ms. When operated on a signal that has undergone both-wave rectification by the waveform shaping circuit from AC power supply A, 50
The same result will be obtained if counting is allowed for each integral multiple of ms.
Although the above embodiment is realized by a circuit, it can be realized by control using a one-chip computer equipped with a timer and an interrupt mechanism.

Instead of counting all power wave numbers, 1
By providing the counting permission period in which the number of power source waves is counted by about 1 per 100 ms only, it is possible to measure time with the same device regardless of which power source frequency is different. AC within a certain time when AC power is turned on
There is a possibility that the determination of 50/60 Hz may be wrong. This is because the AC power waveform is intermittent due to contact / non-contact of the power plug. Due to the erroneous determination of 50/60 Hz, the way the clock progresses is halved.

The present invention avoids this danger in principle. It also has the effect of suppressing malfunctions due to noise. Even if a noise such as e in FIG. 3 is generated, it does not affect since it is not the counting permission period at this time. Further, even if noise such as f is generated, since it is counted only once, it does not affect even during the counting permission period.

Further, even if the power supply waveform disappears due to an instantaneous blackout or the like, it can be corrected. Even if an instantaneous power failure as shown by the AC power supply waveform A occurs in the counting permission period of FIG. 3d, a correction count pulse of g is created, and the correction is automatically corrected and counted by the counting circuit 3. Does not affect the clock timing. In the case of a power failure for a long time, a back-up battery keeps time with the accuracy of the crystal oscillator based on the reference clock, and a correction pulse is continuously generated, but when the AC power supply is connected, it is controlled to the center of the counting permission period. Therefore, the occurrence of error can be reduced.

[0025]

According to the present invention, even when power supplies of different frequencies are used, the gate is opened and counted for a limited time only at the timing when the power supply frequency is common. It is possible to perform timekeeping that prevents an error from occurring.

[Brief description of drawings]

FIG. 1 is a block diagram of an embodiment according to the present invention.

FIG. 2 is a diagram for explaining a counting permission period in a power supply waveform.

FIG. 3 is a diagram for explaining timing of timing based on a power supply waveform.

[Explanation of symbols]

 1 Shaping circuit 2 AND gate 3 Counting circuit 4 Control circuit 5 Memory 6 Counter 7 Oscillation circuit 8 Display

Claims (4)

[Claims] 1. An apparatus for performing highly accurate timekeeping from a power supply frequency utilizing the fact that the frequency of an AC power supply is constant,
A means for measuring time with accuracy using the internal oscillator as a signal source, a means for checking the power supply waveform and counting the number of AC power supply waves for time measurement, and an integer multiple of a predetermined period synchronized with the AC power supply frequency from the internal oscillator. A time measuring method comprising means for obtaining a timing for permitting the power source wave number to be measured, and means for counting and counting the power source wave number for time measurement at the above timing. 2. An apparatus for performing highly accurate timing from a power supply frequency by utilizing the fact that the frequency of an AC power supply is constant,
A means for measuring time with accuracy using the internal oscillator as a signal source, a means for checking the power supply waveform and counting the number of AC power supply waves for time measurement, and an integer multiple of a predetermined period synchronized with the AC power supply frequency from the internal oscillator. A timepiece comprising means for obtaining a timing for permitting the power supply wave number to be measured, and means for counting and counting the power supply wave number for time measurement at the above timing. 3. The time measuring method according to claim 1, wherein the predetermined period is N × 50 ms, where N is an integer. 4. An apparatus for performing highly accurate timekeeping from a power supply frequency by utilizing the fact that the frequency of an AC power supply is constant,
A means for obtaining a clock signal with accuracy using the internal oscillator as a signal source, a means for checking the power supply waveform to count the number of AC power supply waves for time measurement, and an integer for a predetermined period synchronized with the AC power supply frequency from the internal oscillator. A means for obtaining a predetermined timing that permits the presence or absence of the repetition of the power wave number for each multiple, a means for counting and counting the power wave number for time measurement at the above timing, and a means for counting when the above count is lacking. A time measuring method comprising means for correcting.