EP0250142A2

EP0250142A2 - Electronic timepiece

Info

Publication number: EP0250142A2
Application number: EP87305066A
Authority: EP
Inventors: Yasushi Nakabayashi
Original assignee: Seiko Instruments Inc
Current assignee: Seiko Instruments Inc
Priority date: 1986-06-19
Filing date: 1987-06-09
Publication date: 1987-12-23
Also published as: EP0250142A3; CN87104335A; JPS62299785A; KR880000838A; JP2562302B2

Abstract

A multi-function analog electronic timepiece displays one of at least two different time data using the hour, minute and second hands, the displayed time data being changed upon external operation a switch. When the display mode is to be changed, a processor 5 of the timepiece calculates the time difference between the displayed time and the time to be displayed next, and automatically determines whether the hands are to be quickly driven in clockwise or counterclockwise directions to the destination time, in order to minimise the time required for changing the time data and to decrease the consumption of electric power required for driving by the reversible motor drive means 8.

Description

The present invention relates to electronic timepieces, and particularly those including minute and hour hands to display time, the mode of display being changeable. When the displayed time has to be altered upon a change of mode with such an electronic timepiece, the hands are turned clockwise by the motor which drives the hands irrespective of the time difference between the currently displayed time and the time that is to be displayed in the next mode. Even if the speed of rotation of the hands by the motor is increased, an extended period of time may be required to drive the hands to display the next time required by the change of mode. If, for example, the time displayed at the present time is 12:00 and the time to be displayed in the next mode is 11:59, the hands must be driven by an amount of eleven hours and fifty-nine minutes. If a period for driving the minute hand is 20 seconds and a period for forward driving is 64 Hz, then a time of about 33.7 seconds is required for quickly driving the hands to display the next time. In other words, the next time display is obtained after about 34 seconds have passed.
It is an object of the present invention to provide means for reducing the time required for changing the time displayed upon a mode change.
According to the present invention, the motor for driving the hands is reversible and the time difference between the presently displayed time and the time that is to be displayed is compared to predetermined amounts to determine whether the hands are to be rotated clockwise or counterclockwise to reach the desired position by the shorter route.
According to one aspect of the present invention there is provided an electronic timepiece including minute and hour hands to display time, a reversible motor to rotate the hands, externally operable means to change the mode of display, means for determining the time difference between the presently displayed time and the time that is to be displayed upon a change of mode, and for comparing the determined time difference to a predetermined amount or amounts to determine whether the hands are to be rotated clockwise or counterclockwise to reach the desired position by the shorter route, and means for driving the motor accordingly.
According to another aspect of the present invention there is provided a multi-function analog electronic timepiece comprising an oscillation circuit employing a quartz oscillator as a source of oscillation, a frequency-dividing circuit for dividing the frequency of the output signal of the oscillation circuit, means for generating timing clock signals in response to a plurality of output signals of the frequency dividing circuit, and motor means for driving the hands, characterised by means for counting and storing times of a plurality of time functions which correspond to a plurality of display modes by the hands, means for storing the presently display time, means for forming forward waveforms for rotating the motor clockwise, means for forming reverse waveforms for rotating said motor counterclockwise, means for controlling the inputs from externally operable means to change the mode of display, means for comparing time data of the presently displayed mode and of the next to be displayed mode upon a change called for by the means for controlling the inputs, and determining which waveforms are to be supplied to the motor means to enable the hands to reach the desired position by the shorter time.
When the mode is to be changed, it is automatically determined whether the hands be driven quicker to the time that is to be displayed in the next mode in the forward direction than in the reverse direction. This enables the time in the next mode to be quickly read and enables the device to be quickly operated.
When the display data is to be changed, this is effected by a switch input from an external member so that the timepiece can indicate different time data such as the present time, alarm-set time, or the time in a selected part of the world, using the hands of hour, minute and second.
An embodiment of the invention is now described with reference to the accompanying drawings, in which:-

Figure 1 is a block diagram of an embodiment of the present invention;
Figure 2 is a block diagram illustrating in detail part of the processor of Figure 1; and
Figure 3 is a flow chart illustrating the steps of operation in the processor.

An oscillator circuit 1 (Figure 1) has a quartz oscillator as a source of oscillations and an output to a frequency-dividing circuit 2 which divides the frequency of outputs of the oscillation circuit 1 and provides a plurality of outputs. A timing clock generating means 3 generates timing clock signals, in particular 1 Hz signals, necessary for operating the whole system in response to the plurality of outputs from the frequency-dividing circuit 2. A switch input control means 4 controls the passage of a switch input arbitrarily produced by a user, depending upon the timing of clock generating means 3 to a processor 5. The operation timing of the processor 5 is controlled by the clock generating means 3, and the processor exchanges information with the switch input control means 4, a ROM 6, a RAM 7, and motor drive means 8. The ROM 6 stores the instructions by which the operation procedures of the timepiece are programmed. The RAM 7 temporarily stores time data or the like. The motor drive means 8 drives the hands of the timepiece.
The RAM 7 includes means 9 (Figure 2) for counting seconds, means 10 for counting minutes, means 11 for counting hours, means 12 for storing the minutes of alarm, means 13 for storing the hour of alarm, means 14 for counting the minutes of world time, means 15 for counting the hours of world time, and means 22 for storing the presently displayed condition. They are connected via a bus line 21 to means 17 (forming part of processor 5) which executes comparison and operation. Also connected to the bus line 21 are means 16 for controlling the switch input forming part of the switch input control means 4, means 18 for forming forward waveforms to drive the motor to move the hands clockwise and means 19 for forming reverse waveforms to drive the motor in the reverse direction to move the hands counterclockwise. Means 20 for driving the motor is part of the motor drive means 8 and is connected to means 18 and means 19 to drive the hands in the appropriate direction upon receipt of outputs thereof.
In response to 1 Hz signals produced by clock generating means 3, the count of seconds in means 9 is read, via bus line 21, into the means 17 which adds one to the count and compares the result with a count of 60. The means 17 thus determines whether the count in means 9 plus one is 60 or not. When the determination is negative, the incremented count is stored, via bus line 21, in means 9 which thus counts up the seconds.
When the determination is positive, that is, the incremented count is 60, the count in means 9 is rewritten as zero by means 17 and the count of minutes in means 10 is read, via bus line 21, into means 17 which adds one to the count and compares the result with a count of 60. The means 17 thus determines whether the incremented count of minutes is 60 or not. When the determination is negative, that is, the incremented count is not 60, the incremented count is stored, via bus line 21, in means 10 which thus counts up the minutes. When the determination is positive, that is, the incremented count is 60, the count in means 10 is rewritten as zero by means 17 and the count of hours in means 11 is incremented by one and compared to 12 in a similar manner. The means 11 that counts the hours, the means 14 that counts the minutes of the world time, and the means 15 that counts the times of the world time, perform operations similar to the above-mentioned operation for counting the seconds and minutes instructions to carry out these operational procedures are stored in the ROM 6.
The data in means 22 that stores the presently displayed condition is read via bus line 21 and is compared with data in means 9, 10 and 11 to determine whether the hands must be moved or not. When the hands must be moved, means 17 also determines whether the hands must be turned in the clockwise direction or counterclockwise direction, and how many pulses are needed to produce the desired time display. Means 17 then sends corresponding data via bus line 21, either to means 18 or to means 19. According to whether the hands are to be driven clockwise or counterclockwise, forward or reverse waveforms are sent by means 18 or 19 to means 20 that drives the motor. When the data in means 22 indicates that the hands are in the desired display position, the means 18 or 19 cease to send on drive waveforms.
Whilst the ordinary operation of the system is as described above, a change of mode can be called for as a result of switch operation by the user, and the change is input from switch input control means 4 and means 16 via bus line 21 to means 17 which executes the comparison and operation. For instance, one change is from display of the present time to the display of alarm-set time. First, the count of means 11 which counts the hours is input, via bus line 21, to means 17 and, then, the count of means 13 which stores the hour of alarm is input, via bus line 21, to means 17. The former is subtracted from the latter and it is then determined whether the resultant difference has a positive value, a negative value or is zero. If the difference is positive it is then determined whether or not it is equal to or greater than 9. When the difference is greater than or equal to 9, counterclockwise rotation of the hands is effected until the desired display is reached. When the difference is less than 9, clockwise rotation of the hands is effected. When the resultant difference has a negative value, it is determined whether or not the absolute value thereof is greater than or equal to 3. When the absolute value is greater than or equal to 3, clockwise rotation of the hands is effected. When the absolute value is less than 3, counterclockwise rotation of the hands is effected. When the resultant difference is zero, the count of means 10 that counts the minutes is input, via bus line 21, to means 17 and the count of means 12 which stores the minute of alarm is input, via bus line 21, to means 17 and the former is subtracted from the latter. It is then determined whether the resultant difference is positive, negative or zero. When the difference is positive, clockwise rotation of the hands is effected and when the difference is negative, counterclockwise rotation of the hands is effected. When the difference is zero, no operation is performed.
During clockwise rotation of the hands, data for forward drive is sent, via bus line 21, to means 18 that forms forward waveforms and thus to means 20 that drives the motor to drive the hands forward. At the same time, one is added to the count of the presently displayed "hour" and "minute", and the counts are compared in means 17 with the counts of "hour" and "minute" of alarm which is the destination. The operation is repeated until they become in agreement with each other. During counterclockwise hand rotation, likewise one is subtracted from the count of the presently displayed "hour" and "minute" and the operation is repeated until the counts are in agreement with each other.
The following control operation is executed once whenever the switch is input by the user. When an interrupt is input in a step A (Figure 3) which is waiting for an interrupt it is first determined in step B whether or not it is a key input of the switch. If the determination is negative (N), the program proceeds to step C and another operation unrelated to the invention occurs. When the determination is positive (Y), the program proceeds to step D which discriminates whether or not the switch input is a mode change. When the determination is N, the program proceeds to step E and another operation occurs. When the determination is Y, the program proceeds to step F. In step F the data of the presently displayed "hour" is transferred to RA, and step G follows, in which the data of "hour" of the destination time is transferred to RB. Step H follows in which data in RA is subtracted from the data in RB. The program then proceeds to step I, when it is determined whether the difference (RB-RA) is more than, equal to or less than zero. When the difference is ''0'' in the step I, the program proceeds to step L. When the difference has a positive value in the step I, the program proceeds to step J. When the difference has a negative value in the step I, the program proceeds to step K.
In step J, it is determined whether or not the absolute value of the difference is greater than or equal to 9. When the determination is Y, the program proceeds to step Q and when the determination is N, the program proceeds to step P. In step K, it is determined whether or not the absolute value of the difference is greater than or equal to 3. When the determination is Y, the program proceeds to the step P and when the determination is N, the program proceeds to step Q. In the step P, one is added to the minute count of the presently displayed hour and minute, and step R follows, in which the forward waveforms come from means 18 to move the hands forward by an amount of one minute. In a following step T, it is determined whether or not the result of step P is in agreement with the hour and minute of the destination time. When the determination is Y, processing is finished and when the determination is N, the program returns to step P to repeat the operations of steps P, R and T.
In the step Q one is subtracted from the minute count of the presently displayed hour and minute, and step S follows, in which reverse waveforms come from means 19 to move the hands backwards by an amount of one minute. In a following step U, it is determined whether or not the result of step Q is in agreement with the hour and minute of the destination time. When the determination is Y, processing is finished and when the determination is N, the program returns to step Q to repeat the operations of steps Q, S and U.
In step L the data of the presently displayed "minute" is transferred to RC, and step M follows, in which the data of minute of the destination time is transferred to RD. In following step N, the count in RC is subtracted from the count in RD, and in following step O, it is determined whether the difference (RD-RC) of the step N is zero or has a positive value or negative value. When the difference is positive, the program proceeds to the step Q, when the difference is negative, the program proceeds to the step P, and when the difference is zero, the program is completed.
Thus, the difference between the hour count of the displayed time and the hour count of the destination time is used to determine the direction of rotation of the hands to be effected. As rotation proceeds, the motor drives the hands clockwise or counterclockwise in steps of one minute and the system checks whether the displayed and destination times agree. Thus, any initial difference including a minute count is reduced until it is completely eliminated. However, if there is no difference between the hour counts of the displayed and destination times, any difference between the minute counts thereof is used to determine the direction of the hands to be effected, and the same checking takes place at each step of one minute.
The described embodiment is based upon a timepiece having a reversible motor capable of rotating the hands clockwise at twice the speed that it can rotate them counterclockwise. It is this that decides the comparison counts in steps J and K, because it takes as long to rotate the hands counterclockwise for 4 hours as to rotate the hands clockwise for 8 hours. It will be appreciated, therefore, that comparison counts other than 3 and 9 may be used, in particular when other relative speeds of forward and reverse rotation are available.
If the clockwise and counterclockwise speeds of rotation of the hands are equal, for example, a positive time difference in hours can be compared to six to determine if it is equal to or greater than six for counterclockwise rotation or less than six for clockwise rotation. A negative time difference so compared would require counterclockwise rotation if less than six.
It will be appreciated that after a mode change to display the hour and minute of alarm, another mode change will be effected to return to the display of present time. The operations program is effectively the same as shown in Figure 3, except that it is the hour count in means 11 and the minute count in means 10 which are transferred to RB and RD in steps G and M, respectively. In the same way, a mode change to the display of world time can be achieved by transferring the hour count in means 15 and the minute count in means 14 to RB and RD in steps G and H, respectively.
According to the present invention as described above, when the mode is changed, it is automatically determined whether the hands are to be driven clockwise or counterclockwise to arrive at the time display of a newly designated mode, and the hands are driven requiring a minimum period of time.
The above embodiment has dealt with the case where the frequency of forward driving pulses is twice as high as the frequency of reverse driving pulses. Therefore, the data for discriminating whether the hands be turned forwardly or reversely changes with the change in the difference between these frequencies.

Claims

1. An electronic timepiece including minute and hour hands to display time, a reversible motor to rotate the hands, externally operable means to change the mode of display, means (5,17) for determining the time difference between the presently displayed time and the time that is to be displayed upon a change of mode, and for comparing the determined time difference to a predetermined amount or amounts to determine whether the hands are to be rotated clockwise or counterclockwise to reach the desired position by the shorter route, and means (18,19,20) for driving the motor accordingly.

2. A timepiece as claimed in claim 1 in which the motor is operable to drive the hands clockwise at a speed different from that counterclockwise, and the predetermined amounts differ according to the direction of the difference.

3. A timepiece as claimed in claim 2, in which the selected route is the shorter in time.

4. A timepiece as claimed in claim 2 or 3, in which the motor is operable to drive the hands clockwise faster than counterclockwise.

5. A timepiece as claimed in any preceding claim, in which the difference in time is determined from the hour counts of the displayed time and the time to be displayed.

6. A timepiece as claimed in claim 5, in which the difference in time is determined from the minute counts of the displayed time and the time displayed, if there is no time difference between the hour counts.

7. A timepiece as claimed in any preceding claim, including means to change the mode of display from a display of present time at least to a display of alarm set time, and vice versa.

8. A multi-function analog electronic timepiece comprising an oscillation circuit (1) employing a quartz oscillator as a source of oscillation, a frequency-dividing circuit (2) for dividing the frequency of the output signal of the oscillation circuit (1), means for generating timing clock signals (3) in response to a plurality of output signals of the frequency dividing circuit (2), and motor means (8) for driving the hands, characterised by means (9,10,11,12,13) for counting and storing times of a plurality of time functions which correspond to a plurality of display modes by the hands, means (22) for storing the presently display time, means (18) for forming forward waveforms for rotating the motor clockwise, means (19) for forming reverse waveforms for rotating said motor counterclockwise, means (16) for controlling the inputs from externally operable means to change the mode of display, means (17) for comparing time data of the presently displayed mode and of the next to be displayed mode upon a change called for by the means (16) for controlling the inputs, and determining which waveforms are to be supplied to the motor means to enable the hands to reach the desired position by the shorter time.

9. A timepiece as claimed in claim 8, in which the pulse frequency of the forward waveforms is different from the pulse frequency of the reverse waveforms.

10. A timepiece as claimed in claim 9, in which the pulse frequency of said forward waveforms is higher than the pulse frequency of the reverse waveforms.