Apparatus and method for setting a value to be displayed

Abstract: An electronic clock in which a time can be set securely and quickly at a stable rate with favourable operability. The electronic clock is provided with an input time counting means (103) for counting a time during which an input control means (102) detects a continuous input signal sent from a switch (211) by using clock signals generated by a frequency divider (101) for dividing down the frequency of a source oscillator (106), an input time detecting means (104) for detecting the fact that a value obtained by this input time counting means (103) reaches a predetermined value, and a setting increment/decrement control means (105) for varying a setting increment or decrement (in units of a unit time, e.g. one minute) to be added to or subtracted from a currently set value of time every period corresponding to a clock signal generated by the frequency divider (101). Further, this electronic clock is constructed in such a manner that the increment or decrement is increased or decreased at a rate of 2 n (n = 1, 2, 3, ...) if the input signal is continuously input from the switch. Moreover, this electronic clock may be further provided with a setting-digit selecting means (705) for selecting a time-setting digit, at which a time is set, according to an output of the input time detecting means (703).

Description: The present invention relates to an apparatus and method for setting a value to be displayed. More particularly, but not exclusively, the invention relates to an electronic timepiece and to a method for setting a value to be displayed by an electronic timepiece. The value may, for example, be a time of day, an alarm time or the like. In one aspect the present invention relates to the improvement of a time setting means which enables the time to be set quickly and accurately. In conventional electronic clocks, what is called an even-rate time advancement method, by which a unit time is continuously added to or subtracted from the current set time at an even or uniform rate after a time setting switch is operated for one or two seconds, has been widely used as a method by which operators set the time. As an improvement of this setting method, there has been also used a variable-rate time advancement method by which the frequency of adding (or subtracting) a unit time is changed according to the duration of the setting switch operation. In the case of this variable-rate time advancement method, a clock rate or speed, which is a control frequency of a time control means (for instance, a microcomputer) for performing an addition (or subtraction) of a unit time, is successively changed, for example, from 8 to 16 to 32 to 64Hz. In accordance with this method, as the duration of the setting switch operation becomes longer, the rate of change in time becomes larger, i.e. a time advancement rate increases. Thus, this method has an advantage in that in the case where a target time to be set is far away from the currently set time, the period required to attain the target time can be reduced. The aforementioned conventional electronic clocks, however, have the following problems associated therewith. First, in the case of employing the even-rate time advancement method, if a time advancement rate is set as being relatively low, for instance if a unit time is added at a frequency of 8Hz, it can take a long time to set the target time. In contrast, if the time advancement rate is set as being high, the target time may be immediately exceeded on operation of the setting switch, and it is thus difficult to set the target time correctly. Further, in variable-rate time advancement, addition or subtraction processing of a unit time is periodically performed by a time control means such as a microcomputer. When the time advancement rate is low these methods are satisfactory. However, when the clock speed is, for example, 32 or 64Hz, the period available for performing the addition or subtraction processing becomes short. It is, therefore, possible that the processing cannot be completed within an operation cycle corresponding to the clock rate of 32 or 64Hz. Consequently, the periodic additions or subtractions may not be surely performed (for example, additions or subtractions may not be stably performed at a uniform rate), and thus the time setting operation becomes difficult for the operator to control. For example, the operation may be stopped for a moment in the middle of time advancement, and this causes an operator to feel that the operation has got stuck halfway through. This problem is not confined to mere a sensory issue. The instability in operation speed at which an addition or a subtraction is performed leads to real difficulty in setting the time. Namely, the unstableness and unevenness of the operation speed cause the user to find it difficult to predict when he should release the switch during the time advancement, i.e. when he should discontinue the time advancement to facilitate setting the target time. One proposal for stably performing; additions or subtractions, and thereby reducing the effect of the above problems, is to reduce a one-instruction execution time of the microcomputer by increasing the clock frequency (or source frequency) of the system clock. This results in an increase in current consumption and also results in an increase in the lower limit of an operation voltage of the microcomputer. Consequently, the life of the battery powering the microcomputer is shortened. Moreover, in the case of an ordinary clock, a source oscillator having an oscillating (or source) frequency of 32.768 kHz is necessary for measuring time intervals. Thus, a second oscillator having an oscillating frequency different from 32.768 kHz may be necessary. Consequently, this conventional method is disadvantageous in that the number of components may be increased, which makes the electronic clock large in size and more expensive. Moreover, the current consumed by a microcomputer has a part regularly consumed in a hardware portion thereof and another part consumed by executing software. The addition or subtraction processing is performed at high frequency, i.e. at time intervals corresponding to the clock frequency of 32 or 64Hz, by executing software programs. This also results in increase in current consumption and a decrease in the life of the battery. Furthermore, in the case where there is no processing other than the addition or subtraction processing to be performed every period corresponding to the frequency of 32 or 64Hz, the microcomputer, which should be in a stand-by state or a stopped state, is activated. This also causes an increase in current consumption and a decrease in the life of the battery. DE-A-2 654 305 (fig.s 1,2) discloses circuitry for controlling electronic timepieces having a time unit counter controlled by the frequency divider of a reference frequency source and also a digital time display device controlled by said time unit counter. Setting pulses of variable pulse sequence frequency can be inserted into said time unit counter. The setting pulse generating means consist of a voltage controlled oscillator and are thereby generating automatically a pulse sequence frequency of the setting pulses which is variable in time when the setting sequence has been initiated. EP-A-0 110 850 discloses (fig. 1) a device for setting a numeric display (11) comprising a continuously turnable potentiometer (12) by which the setting area can be repeatedly passed through by turning in the same direction by simple and cheap means. The potentiometer and the display are connected to a computer (10), preferably a microcomputer. The computer is arranged to repeatedly sense the instantaneous resistance value of the potentiometer or a parameter representing said value. Further, the computer is arranged to store the first one (T 1high ) of a series of measurement values and for each subsequent measurement value (T 2high ) in the series to determine if the difference between the present and the first measurement value exceeds a reference value (T diff ), in which case the display (11) is operated to increase or decrease its value by one step of a predetermined magnitude. GB-A-2 260 207 (fig. 1) describes a device for altering a value displayed on an electronic digital display 9, which allows quick and smooth adjustment of the display value, has pulse generating means 1 for generating pulses through manual operations, counting means 6 for counting the number of pulses in predetermined time intervals, specifying means 7 for specifying adjustment values to be used for the adjustment of an electronic digital display value in accordance with the count values, and calculation means 10 for adding or subtracting the adjustment values to or from said electronic digital display value. The apparatus and method according to the present invention are intended to solve/reduce the aforementioned problems. Accordingly, an object of the present invention is to realize an electronic timepiece in which a time can be set securely and quickly at a stable time advancement rate. Further, another object of the present invention is to realize an electronic timepiece in which a time can be set relatively easily by the user. Moreover, a further object of the present invention is to realize an electronic timepiece which can prevent an increase in unnecessary current consumption and does not impose an excessive load on software used in a time control means such as a microcomputer. Furthermore, still another object of the present invention is to provide a method for setting a time in an electronic timepiece, by which the frequency of a clock signal used for performing additions or subtractions in a time control means such as a microcomputer is held constant and a unit time to be added or subtracted is changed according to the duration of an operation of a setting switch for setting a time. In other words, addition or subtraction processing for achieving adjustment of the time is performed at regular time intervals (i.e. the timing or regulation of this processing is effected in such a manner that the operation speed is constant) and the amount of time to be added or subtracted is changed according to the duration of an operation of the setting switch. According to a first aspect of the present invention, there is provided an apparatus having a display for displaying a value, and means for adjusting at adjustment time intervals the value to be displayed in response to a user input such that the rate of adjustment varies over a period of time, characterised in that the variation of the rate of the adjustment is provided by varying the amount by which the value is incremented/decremented at the adjustment time intervals, and the amount by which the value is incremented/decremented at the adjustment time intervals is increased as the duration of the user input increases. In the conventional variable rate time adjustment method discussed above, the amount by which the value (time) is incremented/decremented at the adjustment time intervals is always the same, and the variation in rate of adjustment over a period of time is provided by increasing the frequency of the adjustment time intervals - the disadvantages of which have already been described. In the present invention, by varying the amount by which the value is incremented/decremented at the adjustment time intervals, the need to increase the frequency of the adjustment time intervals to increase the rate of change of the value to be displayed may be reduced or eliminated. The value displayed may be a time, and four display digits may be provided which display tens of hours, hours, tens of minutes and minutes, respectively. The value may be incremented/decremented by selecting different ones of the display digits to have their values altered at different adjustment time intervals. For example, at one time interval the minutes display digit may be altered, whereas at a subsequent time interval the tens of minutes display digit may be altered. According to a second aspect of the present invention, there is provided a method of setting a value to be displayed, the method comprising adjusting at adjustment time intervals the value to be displayed in response to a user input such that the rate of adjustment varies over a period of time, characterised in that the variation of the rate of the adjustment is provided by varying the amount by which the value is incremented/decremented at the adjustment time intervals, and the amount by which the value is incremented/decremented at the adjustment time intervals is increased as the duration of the user input increases. The invention may be realised as an electronic clock comprising: (a) a frequency divider means for dividing down a frequency of a source oscillator and for generating a clock signal; (b) an input control means for detecting a switch input signal to be used for setting a time; (c) an input time counting means for counting a period of time during which the input control means detects a continuous input signal sent from the same switch by using the clock signal generated by the frequency divider means; (d) an input time detecting means for detecting a fact that a value of the period measured by the input time counting means reaches a predetermined value; and (e) a setting increment/decrement control means for establishing predetermined periods of time according to the clock signal generated by the frequency divider means and for varying a setting increment or decrement of a set value of a unit time to be added or subtracted each of the predetermined periods of time, which is formed using an output clock signal of the frequency divider means 101, according to an output of the input time detecting means. Preferably, the setting increment and decrement to be used by the setting increment/decrement control means is initially set as ± 1 unit time, wherein after a lapse of a predetermined period, the setting increment and decrement are changed to ±2 n (n is an integer equal to or greater than 1). Conveniently, the input time detecting means counts clock signals, each of which has a frequency of 1 Hz and is generated by the frequency divider means, wherein the setting increment/decrement control means operates in response to each clock signal which has a frequency of 8 or 16 Hz and is generated by the frequency divider means. The invention may also be realised as an electronic clock comprising: (a) a frequency divider means for dividing down a frequency of a source oscillator and for generating a clock signal; (b) an input control means for detecting a switch input signal to be used for setting a time; (c) an input time counting means for counting a period of time during which the input control means detects a continuous input signal sent from the same switch by using the clock signal generated by the frequency divider means; (d) an input time detecting means for detecting a fact that a value of the period measured by the input time counting means reaches a predetermined value; and (e) a setting-digit selecting means for selecting a time-setting-digit, at which a time is set, according to an output of the input time detecting means. Preferably, the clock further comprises a non-selected digit display control means for displaying an arbitrary value at each of digits other than the time-setting-digit selected by the setting-digit selecting means. Conveniently, the clock further comprises a non-selected digit display control means for displaying a value at each of digits other than the time-setting-digit, which is selected by the setting-digit selecting means, by blinking the value thereat and for turning off an indication of the value displayed at each of the digits other than the time-setting-digit. The non-selected digit display control means may operate at a speed faster than an operating speed of a display means caused by the setting-digit selecting means to operate. The invention may further be realised as a method for setting a time, comprising the steps of: counting a period of time, during; which a switch input signal is continuously input, by using clock signals generated by a frequency divider means which divides down a frequency of a source oscillator; and changing a set time by varying a set value of a unit time every predetermined constant period of time according to a counted value of the period of time. Preferably, when varying the set value of a unit time, a setting increment or decrement of the unit time is initially set as ± 1 unit time, and after a lapse of a predetermined period, the setting increment or decrement is changed to ±2 n (n is an integer equal to or greater than 1). Conveniently, the step of counting a period of time, during which a switch input signal is continuously input, comprises the sub-steps of: using clock signals, each of which has a frequency of 1 Hz and is generated by the frequency divider means; and calculating the set value of the unit time in response to each clock signal which has a frequency of 8 or 16 Hz and is generated by the frequency divider means. Optionally, the set value of the unit time is varied every predetermined constant period by selecting a time-setting-digit at which a time is set. An arbitrary value may be displayed at each of digits other than the selected time-setting-digit. A value displayed at each of digits other than the selected time-setting-digit may be blinked or turned off. Preferably, a value is displayed at each of the digits other than the selected time-setting-digit at a speed faster than a displaying speed at which a value is displayed at the selected time-setting-digit. For a better understanding of the invention, embodiments will now be described by way of example with reference to the accompanying drawings, in which:- Fig. 1 is block diagram for illustrating a first embodiment of an electronic clock; Fig. 2 is a diagram for illustrating the configuration of hardware of the electronic clock; Fig. 3 is a block diagram for illustrating the further detail of the first embodiment of the electronic clock; Fig. 4 is flowchart of a program used in the electronic clock of the first embodiment; Figs. 5(a) to 5(d) are timing charts for illustrating operations of the electronic clock of the first embodiment; Fig. 6 is a supplemental flowchart to that of Fig. 4, which may be employed if the time setting switch is operated for a long period of time; Fig. 7 is a block diagram for illustrating the second embodiment of an electronic clock; Fig. 8 is a block diagram for illustrating the configuration of the electronic clock, which has a non-selected digit display control means in addition to other elements of the second embodiment; Fig. 9 is a block diagram for illustrating further detail of the second embodiment of the electronic clock; Fig. 10 is a flowchart of a program used in the electronic clock of the second embodiment; and Fig. 11 is a supplemental flowchart to that of Fig. 10, for illustrating an example of a display control operation of a non-selected digit display control means. In the drawings, like reference numerals designate like or corresponding elements. The embodiments described all relate to clocks. However, the invention can be applied to any device giving an indication of time (a timepiece), and many other types of devices. For example the principles disclosed could be applied to setting the temperature on an electronic thermostat. Thus, the invention relates to adjusting values other than time. The values may be numerical values or letters of the alphabet, for example. In the specification, the expression "a time" is used not only to designate hours, minutes and seconds but also to designate "time" information in a broad sense, which includes the date and the day of the week. First, the configuration of an electronic clock will be described. A first embodiment of an electronic clock is shown in a block diagram of Fig. 1. The electronic clock includes a frequency divider means 101 for "dividing down" (namely, generating a signal having a frequency of an integral submultiple of) the frequency of a source oscillator 106, such as a crystal oscillator, for outputting clock signals. An input control means 102 detects a switch input (signal) generated by operating a switch 107 for setting the time. An input time counting means 103 for counting or measuring a period of time during which the input control means 102 detects a continuous input signal generated by operating the switch 107 using the output clock signals of the frequency divider means 101. An input time detecting means 104 detects when the period measured by the input time counting means 103 reaches a predetermined value. The output of the input time detecting means 104 is input to a setting increment/decrement control means 105 which varies the amount by which a time value to be altered is incremented or decremented in a given predetermined period (which is formed using the output clock signal of the frequency divider means 101) in accordance with the input. A clock signal (namely, a one-second signal) having a frequency of 1Hz is required by the clock to count or measure a time interval. Further, it is preferable that a source oscillator has a predetermined oscillating frequency which is "divided down" by the frequency divider 101 into multiple levels or stages in such a way that the ratio between the adjoining levels is (1/2). This is intended to simplify the configuration of the frequency divider means or circuit 101. Therefore, the frequency divider means 101 can easily generate a clock signal having a frequency of 2 n Hz (n is an integer equal to or greater than 0). Moreover, the use of a clock signal having a frequency of 2 n Hz is advantageous because both the input time counting means 103 and the setting increment/decrement control means 105 use output clock signals of the frequency divider means 101. Thus, it is preferable that the input time counting means 103 counts the clock signal having a frequency of 1Hz output from the frequency divider means 101. The clock signal having a frequency of 1Hz may be used to measure a continuous input time during which a continuous input signal generated by operation of the switch is detected. The releasing of the switch 107 is detected at a higher frequency than 1Hz in order that the time may be set accurately. The use of the clock signal having a frequency of 1Hz for measuring continuous operation of the switch 107 is advantageous because such clock signals provide a timing which is best suited to the operator, and impose an appropriate load on the software for setting the time. Further, such clock signals are used because an operating time, in which an operator operates the switch for setting the time, is calculated generally in second units, and in view of this operating time, the software for detecting the input time has only to be executed once every second because it is not necessary to detect or calculate the input time at a frequency higher than 1Hz. Further, it is preferable that the setting increment/decrement control means 105 operates in response to a clock signal having a frequency of 4, 8 or 16Hz, which is generated by the frequency divider means 101. In this case, the reasons why the clock signal having a frequency of 4, 8 or 16Hz is used for the timing of the operation of the setting increment/decrement control means 105 are as follows. If a clock signal having a frequency equal to or lower than 2Hz is used, an operator does not feel that the forwarding is performed at a fast rate, which may irritate the operator. Conversely, if a clock signal having a frequency equal to or higher than 32Hz is used, the load imposed on the software for the addition or subtraction processing increases so that it becomes difficult to complete the processing within an operation cycle. Furthermore, the increment and decrement performed by the setting increment/decrement control means 105 is initially set as ± 1 unit time. It is preferable that, after the passage of a predetermined period, the increment and decrement are changed to ± 2 n (± 2, ± 4, ± 8, ...) units of time. A digital clock can be considered as having four display digits (ignoring any indication of the time in seconds which may be provided). These display digits indicate tens of hours, hours, tens of minutes and minutes, respectively. If, for example, an increment/decrement of 2, 4 or 8 minutes is set by the setting increment/decrement control means 105, the minute digit of the time will be incremented/decrement discontinuously. This means that, in the case of a four minute increment, the intermediate minutes between say four minutes and eight minutes will not be displayed. However, the value of the higher order digit (the ten minute digit) will be continuously incremented. This gives an overall visual impression that the time is being incremented continuously, which generally tends to be favoured by the clock operator. The increment/decrement could also be by ± 2, 4 or 8 hours or seconds. In the case where the time is incremented or decremented by ± 1, ± 2 or ± 4 minutes, the value of the one-minute digit is displayed at a regular time interval (for example, every (1/4), (1/8) or (1/16) of a second) regardless of the value of the time to be set. The rate of increment or decrement increases in a regular manner (i.e. it doubles as time passes - eg. from 2 to 4 minutes and then from 4 to 8 minutes. Thus, it is easy for an operator to predict the rate of change of the time. Consequently, the time can be set precisely and easily. A second embodiment of an electronic clock is shown in Fig. 7. Components 701 to 704 generally correspond to components 101 to 104 of the first embodiment. The output of the input time detecting means 704 is input to a setting digit selecting means 705 which selects the digit to be set according to the input. It is preferable that, as illustrated in Fig. 8, a non-selected digit display control means 801 is provided for displaying given numerical values, symbols, characters and patterns provided in the electronic clock corresponding to the digits other than the digit selected by the setting digit selecting means 705. Thus, the display at each non-selected setting-digit may be controlled in such a manner as to be turned on or off, or in any manner which will help the operator to distinguish between the selected digit and the other digits. Furthermore, it is preferable that the non-selected setting digit display control means 801 operates at a speed faster than the operating speed of addition/subtraction means and display control means which are operated by the setting-digit selecting means 705. This can provide the advantage that it can be known at a glance which digit of the time is being set, and that an operator can smoothly perform a time setting operation without undue difficulty. The embodiments of an electronic clock with an alarm and a method for setting an alarm time will be described in more detail below. Fig. 2 is a diagram for showing the configuration of hardware of an electronic clock. As shown in this figure, the electronic clock consists of a microcomputer 1, a liquid crystal display (LCD) panel 10, a group of switches 11 and an alarm sounding means 14. The microcomputer 1 is operative to control the entire electronic clock. Further, an oscillator circuit 2 employing a crystal oscillator as a source oscillator is built into the microcomputer 1. The frequency of an output of the oscillator circuit 2 is "divided down" by a frequency divider circuit 3. Moreover, an output signal of the frequency divider circuit 3 is used as a system clock signal f. The oscillating frequency of the source oscillator is 32.768 kHz. A divide-by-2 process is repeatedly performed until a signal having a frequency of 1Hz is finally obtained from a signal having the oscillating frequency of the source oscillator. Further, signals having the respective frequencies obtained by the frequency divider circuit 3 are used as clock signals. An output clock signal of the frequency divider circuit 3 is input to an interruption control circuit 4 and is also used as an interruption timing signal. This interruption control circuit 4 is used for controlling interruptions caused by an internal and external signal (not shown) of the microcomputer and is connected to both of an input control circuit 12 and a control circuit 5. The control circuit 5 serves as a primary element for controlling various operations such as those of stopping and activating the microcomputer 1. Moreover, it is the control circuit 5 that controls a time-setting operation which is a characteristic of the present embodiment. An internal bus 15 interconnects the control circuit 5, a read-only memory (ROM) 6 for storing programs to control operations of the electronic clock, a random access memory (RAM) 7 for storing various data needed in the operations of the electronic clock, a display control circuit 9 for controlling a display of the electronic clock, an input control circuit 12 for monitoring the state of the group of switches 11 and an alarm control circuit 13 for controlling a sounding operation of an alarm sounding means 14. Moreover, the frequency divider circuit 3 is also connected to the internal bus 15. Thereby, information representing the slate of the frequency divider circuit 3 can be read by executing a program. Furthermore, the interruption control circuit 4 is also connected to the internal bus 15. Thereby, the establishment of interruption conditions, as well as the reading of an interruption source, can be achieved by executing a program. Additionally, a set-value storing memory 8 for storing a set value of time is provided in a part of the RAM 7. Incidentally, this set-value storing memory 8 is not always provided in the RAM 7. An independent memory or register may be used as the set-value storing memory 8. Further, the set-value storing memory 8 may be provided in a nonvoltalie RAM. The alarm sounding means 14 used in this embodiment is a piezo-electric buzzer. The alarm sounding means is, however, not limited to such a buzzer. Any means for producing a vibration at a predetermined vibration frequency so as to alert the operator, for example, an acoustic loudspeaker, a bell, a tuning fork and a vibrator, may be used as the alarm sounding means. Further, the group of switches 11 are provided in the body (not shown) of the electronic clock and are push-button switches to be operated by an operator. Moreover, the group of the switches 11 consists of an addition switch having the function of incrementing the set time and a subtraction switch having the function of decrementing the set time. Needless to say, in addition to these switches, diverse switches may be appropriately provided in the electronic clock according to the functions of the electronic clock. Incidentally, although push-button switches are employed in this embodiment, the switches are not limited to those of such a type, as a matter of course. For instance, a slide switch and a touch switch may be employed. Furthermore, the group of switches 11 may be provided in a portion of the electronic clock other than the body thereof. For example, a remote control switch, or an input device, such as a keyboard, a pen and a mouse, of electronic equipment, such as a computer, connected to the electronic clock may be used instead of the group of switches 11. Fig. 3 is a block diagram for illustrating the configuration of the electronic clock of the first embodiment. As shown in this figure, the input control means 102, for detecting the input state of each of two switches 211 used respectively for an addition and a subtraction, is connected to the input time counting means 103. The input time counting means 103 counts or measures the period of time during which a signal continuously input from one of the switches is detected, based on an output clock signal of the frequency divider means 101. The input time counting means 103 is connected to the input time detecting means 104 which detects when the value measured by the input time counting means 103 reaches a predetermined value. The output of the input time detecting means 104 is input to the setting increment/decrement control means 105. The increment/decrement control means 105 changes the amount by which a time value to be altered is incremented or decremented or in any given period (which is determined on the basis of an output clock signal of the frequency divider means 101). An addition means 302 and a subtraction means 303 are connected to the setting increment/decrement control means 105 and perform an addition and a subtraction to a value stored in a set-value storing means 208 (corresponding to the set-value memory 8 of Fig. 2) according to an output of the setting increment/ decrement control means 105, respectively. When the addition means or switch is operated, an addition is performed. In contrast, when the subtracting means or switch is operated, a subtraction is performed. The contents of the set-value storing means 208 are displayed on an LCD panel 306 through a display control means 305. The operation illustrated in the block diagram of Fig. 3 will be described by referring to the flowchart of Fig. 4 and the timing chart of Fig. 5. Incidentally, in the following description, only an operation when performing an addition will be described. An operation when performing a subtraction is similar to the operation thereof when performing an addition. Thus, the description of a subtraction operation is omitted. Here, it is assumed that the frequency divider means 101 is adapted to operate at a falling count (namely, at a falling edge) of a clock signal and that the interruption control circuit 4 is adapted to generate an interrupt in synchronisation with a falling edge of a clock signal having a frequency of 1 or 16Hz, which is produced by the frequency divider means 101. In the following description, it will be assumed that an alarm time (in hours and minutes) is to be set. When the addition switch is operated, 1 minute is added to the current set value of the alarm time at the rising edge of a clock signal. After it is detected that a signal is continuously input for a period of 1 to 2 seconds, 1 minute is added to the alarm time at time interval corresponding to the clock frequency of 8Hz while the signal is continuously input. For the next period of 4 seconds 1 minute is added to the alarm time a time intervals corresponding to the clock frequency of 16Hz. For the subsequent period of 4 seconds 2 minutes are added to the alarm time at time intervals corresponding to the clock frequency of 16Hz. Thereafter, 4 minutes are added to the alarm time at time intervals corresponding to the clock frequency of 16Hz. In the case where an interrupt occurs in synchronisation with the falling edge of an internal clock signal having a frequency of 16 or 1Hz, a program illustrated by a flowchart of Fig. 4, which is stored in the ROM 6 of Fig. 2, is executed. In a mode of operation of the clock in which the alarm can be set, the program runs at time intervals corresponding to the clock frequency of 16Hz. In the following description it is assumed that, initially, an alarm time is set as 1:59 and the addition switch is not operated. First, it is detected in step 401 whether or not the addition switch is operated. In the initial state, the addition switch is not operated and thus the program finishes running. In contrast, in the case where this program starts running after the addition switch is operated (namely, at time "a", as illustrated in Fig. 5(a)), it is first detected in step 401 whether or not the addition switch is operated. When it is detected that the addition switch is operated, it is then detected in step 402 whether or not an input signal is a rising edge at this moment. At this moment in this case, the input signal is a rising edge and thus 1 minute is added to the currently set alarm time (namely, 1:59) in step 403, so that the alarm time is changed to 2:00. Then, a value K for counting the length of time during which the input signal is continuously input is reset to 0 in step 404. Subsequently, predetermined information is displayed in step 416. Thereafter, the program finishes running. When the program runs in response to the next interrupt caused after a time interval corresponding to the clock frequency of 16Hz (namely, at time "b" of Fig. 5(a)), it is first detected in step 401 whether or not the addition switch is operated. Subsequently, it is detected in step 402 whether or not the input signal is a rising edge at this moment. However, at this moment in this case, the input signal is not a rising edge. Thus, it is judged in step 405 whether or not a 16-Hz interrupt occurring at intervals corresponding to the clock frequency of 16Hz and a 1-Hz interrupt occurring at intervals corresponding to the clock frequency of 1Hz occurs simultaneously. In this case, a 1-Hz interrupt occurring at intervals corresponding to the clock frequency of 1Hz does not occur at time "b" of Fig. 5(a). Thus it is next judged in step 407 whether or not the value K is less than 2. At the time "b", the value K is 0. Therefore, the program finishes running. In the case where the program starts running in response to the next interrupt occurring at intervals corresponding to the clock frequency of 16Hz (namely, at time "c" of Fig. 5(a)), it is first detected in step 401 whether or not the addition switch is operated. Subsequently, it is detected in step 402 whether or not the input signal is a rising edge at this moment. However, at this moment in this case, the input signal is not a rising edge. Thus, it is judged in step 405 whether or not a 1-Hz interrupt occurs. In this case, a 1-Hz interruption occurs at time "c" of Fig. 5(a). Thus, 1 is added to the current value K (of zero) in step 406, so that the value K is changed to 1. It is then judged in step 407 whether or not the value K is less than 2. At time "c", the value K is 1. Therefore, the program finishes running. Thereafter, an operation similar to that performed at time "b" of Fig. 5(a) is repeatedly performed 15 times. Further, at time "d", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At time "d", a 1-Hz interrupt occurs. Thus, 1 is added to the current value K in step 406. Consequently, the value K is changed to 2. Next, it is judged in step 407 whether or not the value K is less than 2. As described above, the value K is 2 at time "d". Therefore, it is judged in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Because the value K is 2 at this moment, the program advances to step 409 whereupon the contents of the frequency divider means 101 are read and it is judged whether or not the signal level of a clock signal having a frequency of 8Hz is a low (L) level. At this moment, the level of this 8Hz signal is an L level. Thus, 1 minute is added to the current alarm time. As a result, the alarm time is changed to 2:01 in step 410. Then, time information, etc. is displayed in step 416. Thereafter, the program finishes running. At the next time "e", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At time "e", a 1-Hz interrupt does not occur. Thus, it is then judged in step 407 whether or not the value K is less than 2. The value K is 2 at time "e". Therefore, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Because the value K is 2 at this moment, the program advances to step 409. However, in this case, the level of the 8-Hz signal is a high (H) level. Thus, the program finishes running. At time "f", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At time "f", a 1-Hz interrupt does not occur. Thus, it is then judged in step 407 whether or not the value K is less than 2. The value K is 2 at time "f'. Therefore, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Because the value K is 2 at this moment, the program advances to step 409. As at time "d", the level of the 8-Hz signal is an L-level. Thus, 1 minute is added to the current alarm time. Consequently, the alarm time is changed to 2:02 in step 410. Then, time information, etc. is displayed in step 416. Subsequently, the program finishes running. Thereafter, in a period in which the value K is equal to or greater than 2 and less than 6, the operations respectively performed at the times "d", "e" and "f" are repeatedly performed according to whether or not a 16-Hz interruption and a 1-Hz interrupt occur. Therefore, during a period of 4 seconds in which the value K is equal to or greater than 2 and less than 6, 1 minute is added to the current alarm time every period corresponding to the clock frequency of 8Hz. Namely, 8 minutes are added to the alarm time in a period of 1 second. Each time the alarm time is changed, the display of the alarm time is updated. Thus, a total of 33 minutes, which includes 1 minute added when initially operating the switch, are added to the initially set alarm time 1:59. Consequently, the alarm time reaches 2:32. The judgement as to the signal level of the 8-Hz signal is performed in step 409 of Fig. 4 by reading the 8-Hz signal generated by the frequency divider means. Other methods, however, may be used for such a judgement. Further, this program runs at each time interval corresponding to the clock frequency of 16Hz. Thus, the program may be modified in such a manner that a binary counting is performed on the 16-Hz signal and that when the resultant count is 0, 1 minute is added to the alarm time in step 410 but when the resultant count is 1, such an addition is not performed and the program finishes running. Fig. 5(b) is a timing chart for illustrating an operation in the case where the value K reaches 6 as a result of repeating the aforementioned operation of Fig. 5(a) but is less than 10. At time "g", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this time moment, a 1-Hz interrupt occurs. Thus, 1 is added to the value K in step 406, so that the value K becomes 6. It is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Because the value K is 6 at this moment, the program advances to step 411 whereupon it is judged whether or not the value K is equal to or greater than 6 and less than 10. As described above, the value K is 6 at this moment. Thus, 1 minute is added to the current alarm time. Consequently, the alarm time is changed to 2:33 in step 412. Then, time information, etc. is displayed in step 416. Thereafter, the program finishes running. At time "h", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this time moment, a 1-Hz interrupt does not occur. Thus, it is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Because the value K is 6 at this moment, 1 minute is added to the current alarm time. Thus, the alarm time is changed to 2:34 in step 412. Then, time information, etc. is displayed in step 416. Subsequently, the program finishes running. Thereafter, in a period in which the value K is equal to or greater than 6 and less than 10, the operations respectively performed at the times "g" and "h" are repeatedly performed according to whether or not a 16-Hz interrupt and a 1-Hz interrupt occur. Therefore, during a period of 4 seconds in which the value K is equal to or greater than 6 and less than 10, 1 minute is added to the current alarm time every period corresponding to the clock frequency of 16 Hz. Namely, 16 minutes are added to the alarm time in a period of 1 second. Each time the alarm time is changed, the display of the alarm time is updated. At the beginning of the period in which K is equal to or greater than 6 and less than 10, the alarm time is 2:32. At the end of this period, the alarm time reaches 3:36. Fig. 5(c) is a timing chart for illustrating an operation in the case where the value K reaches 10 as a result of repeating the aforementioned operation of Fig. 5(b) but is less than 14. At time "i", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this timing moment, a 1-Hz interrupt occurs. Thus, 1 is added to the value K in step 406, so that the value K reaches 10. It is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Then, it is judged in step 411 whether or not the value K is equal to or greater than 6 and less than 10. As described above, the value K is 10 at this moment, so that the program advances to step 413 whereupon it is judged whether or not the value K is equal to or greater than 10 and less than 14. Because the value K is 10 at this moment, 2 minutes are added to the current alarm time. Consequently, the alarm time is changed to 3:38 in step 414. Then, time information etc. is displayed in step 416. Thereafter, the program finishes running. At time "j", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this timing moment, a 1-Hz interrupt does not occur. Thus, it is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Furthermore, it is judged in step 411 whether or not the value K is equal to or greater than 6 and less than 10. Additionally, it is judged in step 413 whether or not the value K is equal to or greater than 10 and less than 14. Then, because the value K is 10 at this moment, 2 minutes are added to the current alarm time. Thus, the alarm time is changed to 3:40 in step 414. Then, time information, etc. is displayed in step 416. Subsequently, the program finishes running. Thereafter, in a period in which the value K is equal to or greater than 10 and less than 14, the operations respectively performed at the times "i" and "j" are repeatedly performed according to whether or not a 16-Hz interrupt and a 1-Hz interrupt occur. Therefore, during a period of 4 seconds in which the value K is equal to or greater than 10 and less than 14, 2 minutes are added to the current alarm time every period corresponding to the clock frequency of 16 Hz. Namely, 32 minutes are added to the alarm time in a period of 1 second. Each time the alarm time is changed, the display of the alarm time is updated. At the beginning of the period in which K is equal to or greater than 10 and is less than 14, the alarm time is 3:36. At the end of this period, the alarm time reaches 5:44. In this case, the effects of the additions are substantially equivalent to those obtained by performing the addition at intervals corresponding to the clock frequency of 32 Hz. However, in the case of this embodiment, the addition and the displaying are performed at time intervals corresponding to the clock frequency of 16 Hz. Fig. 5(d) is a timing chart for illustrating an operation in the case where the value K reaches and exceeds 14 as a result of repeating the aforementioned operation of Fig. 5(c). At time "k", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this timing moment, a 1-Hz interrupt occurs. Thus, 1 is added to the value K in step 406, so that the value K reaches 14. It is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Then, it is judged in step 411 whether or not the value K is equal to or greater than 6 and less than 10. Then, as described above, the value K is 14 at this moment, 4 minutes are added to the current alarm time. Consequently, the alarm time is changed to 5:48 in step 414. Then, time information, etc. is displayed in step 416. Thereafter, the program finishes running. At time "l", the detection of the operation of the addition switch (step 401), the detection of a rising edge of the input signal (step 402) and the detection of an occurrence of a 1-Hz interrupt (step 405) are performed. At this time moment, a 1-Hz interrupt does not occur. Thus, it is then judged in step 407 whether or not the value K is less than 2. Moreover, it is judged next in step 408 whether or not the value K is equal to or greater than 2 and less than 6. Furthermore, it is judged in step 411 whether or not the value K is equal to or greater than 6 and less than 10. Additionally, it is judged in step 413 whether or not the value K is equal to or greater than 10 and less than 14. Then, because the value K is 14 at this moment, 4 minutes are added to the current alarm time. Thus, the alarm time is changed to 5:52 in step 414. Then, information is displayed in step 416. Subsequently, the program finishes running. Thereafter, in a period in which the value K is equal to or greater than 14, the operations respectively performed at the times "k" and "l" are repeatedly performed according to whether or not a 16-Hz interrupt and a 1-Hz interrupt occur. Therefore, during a period of 4 seconds in which the value K is equal to or greater than 14, 4 minutes are added to the current alarm time every period corresponding to the clock frequency of 16 Hz. Namely, 64 minutes are added to the alarm time in a period of 1 second. Each time the alarm time is changed, the display of the alarm time is updated. In this case, the effects of the additions are substantially equivalent to those obtained by performing the addition every period corresponding to the clock frequency of 64 Hz. However, in the case of this embodiment, the addition and the displaying are performed every time interval corresponding to the clock frequency of 16 Hz. After the value K reaches 14, the operations respectively performed at the times "k" and "l" are repeated. Thus, as illustrated in Fig. 6, it is not necessary to increment the value K. Therefore, operations 405 and 406 in the flowchart of Fig. 4 can be replaced with operations 601 to 603 shown in Fig. 6. Such an arrangement will determine at step 601 whether K=14, and if K does equal 14, then step 407 is immediately performed without needing to test for the 1Hz interrupt. Additionally, in the case of the first embodiment, the set increment is not more than 4 minutes. Of course, the increment may be more than such a value. For example, 8, 10, 16, 20, 30 or 60 minutes may be employed as the increment. Moreover, other various patterns of variation in increment may be employed. For instance, in the case of one of such patterns, the initial increment is set as 1 minute. Thereafter, the increment is changed to 2 minutes, 5 minutes and 10 minutes in this order. However, of such patterns, a pattern, in which the increment increases in the sequence 2 n (n = 1, 2, 3, .....), namely, the increment changes from 1 to 2 and 4 to 8, is most preferable. This is because an operator can easily predict how the increment will change and also can set the alarm time without worrying. Such a rate of increase in increment enables the operator to easily understand the alarm time setting operation, owing to the fact that the rate of change of the increment is always doubled and is thus constant. In addition, although the value displayed in one of the digits of the display (namely, the one-minute digit, in this case) changes discontinuously, the values displayed at digits (namely, the ten-minute digit and the one-hour digit and so forth), whose orders are higher than the order of the time-setting digit, vary continuously. Thus an operator has a feeling of smoothness of operation. Moreover, in the case of this embodiment, the rate of increment is not so large when the value K, for counting the period of time in which the input signal is continuously input from the switch, is relatively small. This is for ease of operation in situations when the alarm time to be set is relatively close to a previously set alarm time. Namely, in the case where a time being relatively close to a previously set time is to be set as the alarm time, a fine adjustment of time is started immediately after the switch is operated. In such a case, if the increment of the time was performed at a high rate from the beginning, a displayed set time may immediately exceed the alarm time to be set. Thus, in this embodiment, the increment varies. Therefore, this embodiment is also effective in the case where a time being relatively far away from a previous set time is to be set as the alarm time. Namely, in the case of this embodiment, all points in time from a time being relatively close to a previously set time and to another time being relatively far away from the previously set time can be set as the alarm time quickly and accurately. Next, the second embodiment of the present invention will be described hereinafter. In this embodiment, the time-setting digit is changed in a different way than in the first embodiment, in which the increment or decrement of the time is varied. In the second embodiment, the increment or decrement is performed in a different manner during a time setting operation. Fig. 9 is a block diagram illustrating the detailed configuration of the second embodiment of the electronic clock. As shown in this figure, an input control means 702 for detecting whether the switch 211 is being operated or not is connected to an input time counting means 703. Further, the input time counting means 703 is connected to a frequency divider means 701 and is operative to count the period of time, during which an input signal continuously input from one of the switches is detected, on the basis of an output signal of the frequency divider means 701. Moreover, the input time counting means 703 is connected to an input time detecting means 704 and is operative to detect when the count value measured by the input time counting means 703 reaches a predetermined value. These elements are similar to the corresponding elements of the first embodiment. The input time detecting means 704 is connected to a setting-digit selecting means 705 which changes the setting digit, at which the time is set, according to a value output from the input time detecting means 704. An addition means 902 and a subtraction means 903 are connected to the setting-digit selecting means 705 and perform an addition and a subtraction according to an output of the setting-digit selecting means 705 to a value stored in the set-value storing means 208. Of the contents of the set-value storing means 208, values respectively held at the digits, whose orders are higher than the order of the selected digit, are displayed on an LCD panel 906 through a display control means 905. Further, values respectively held at digits, whose orders are lower than the order of the selected digit are displayed on the LCD panel 906 through a non-selected digit display control means 801. Hereinafter, an operation of the electronic clock having the configuration as illustrated in the block diagram of Fig. 9 will be described by referring to flowcharts of Figs. 10 and 11. Incidentally, in the following description, only an operation thereof when performing an addition will be described. An operation when performing a subtraction is similar to the operation when performing an addition. Thus, the description of a subtraction operation is omitted. Here, it is assumed that the frequency divider means 701 is adapted to operate at a falling count (namely, at a falling edge) of a clock signal and that the interrupt control circuit 4 of Fig. 2 is adapted to generate an interrupt in synchronisation with a falling edge of a clock signal having a frequency of 1 or 16Hz, which is produced by the frequency divider means 701. In the following description, it will be assumed that an alarm time (in hours and minutes) is to be set. When the addition switch is operated, 1 minute is added to the current set value of the alarm time at the rising edge of a clock signal. After it is detected that a signal is continuously input for a period of 1 to 2 seconds, 1 is added to the value held at the one-minute digit at each time interval corresponding to the clock frequency of 8Hz for 4 seconds in which the signal is continuously input. For the next period of 4 seconds, 1 is added to the value held at the ten-minutes digit at each time interval corresponding to the clock frequency of 8Hz. For the subsequent period of 4 seconds, 1 is added to the value held at the one-hour digit at each time interval corresponding to the clock frequency of 8Hz. Thereafter, 1 is added to the value held at the ten-hour digit at each time interval corresponding to the clock frequency of 8Hz. Needless to say, an alarm time of the type other than the hours-and-minutes type may be set. For example, an alarm time of the hours-minutes-seconds type, the years-months-days and the months-days-hours-minutes may be set. In the case where an interrupt occurs in synchronisation with the falling edge of an internal clock signal having a frequency of 8 or 1Hz and, a program illustrated by a flowchart of Fig. 10, which is stored in the ROM 6 of Fig. 2, runs. In a mode of operation of the clock in which an alarm can be set, the program runs at time intervals corresponding to the clock frequency of 8Hz. First, it is detected in step 1001 whether or not the addition switch is operated. If the addition switch is not operated, the program finishes running. In contrast, in the case where this program starts running after the addition switch is operated, it is first detected in step 401 whether or not the addition switch is operated. When it is detected that the addition switch is operated, it is then detected in step 1002 whether or not an input signal is a rising edge at this moment. Further, if the input signal is a rising edge, the one-minute digit is selected in step 1003 and 1 (minute) is then added to the currently set alarm time in step 1004. Subsequently, a value K for counting the length of time during which the input signal is continuously input, is reset to 0 in step 1005. Subsequently, predetermined information (time information, etc.) is displayed in step 1020. Thereafter, the program finishes running. When the input signal is not a rising edge, it is judged in step 1006 whether or not a 1-Hz interrupt and an 8-Hz interrupt simultaneously occur. If a 1-Hz interrupt occurs, 1 is added to the current value K in step 1007. If no 1-Hz interrupt occurs, such an addition is not performed. It is then judged in step 1008 whether or not the value K is less than 2. If K is less than 2, the program finishes running. If K is not less than 2, it is next judged in step 1009 whether or not the value K is equal to or greater than 2 and less than 6. If equal to or greater than 2 and less than 6, the one-minute digit is selected in step 1010 as the setting digit at which the time is set. Further, 1 minute is added to the currently set alarm time in step 1011. Moreover, the predetermined information is displayed in step 1020. Otherwise, it is next judged in step 1012 whether or not the value K is equal to or greater than 6 and less than 10. If equal to or greater than 6 and less than 10, the ten-minute digit is selected in step 1013 as the setting digit. Then, 10 minutes are added to the currently set alarm time in step 1014. Thereafter, the predetermined information is displayed in step 1020. Otherwise, it is next judged in step 1015 whether or not the value K is equal to or greater than 10 and less than 14. If equal to or greater than 10 and less than 14, the one-hour digit is selected in step 1016 as the setting digit. Then, 1 hour is added to the currently set alarm time in step 1017. Subsequently, the predetermined information is displayed in step 1020. If the value K is not less than 14, the ten-hours digit is selected in step 1018 as the setting digit. Then, 10 hours are added to the currently set alarm time in step 1019. Thereafter, the predetermined information is displayed in step 1020. Incidentally, when setting an alarm time, it is rare that the value K becomes equal to or larger than 14. Thus, this routine is hardly used. Hereunder, it will be briefly described how the alarm time changes during the program illustrated in the flowchart of Fig. 10 is executed. It is assumed that the alarm time is initially set to 1:59 and that the operator operates the addition switch continuously in order to set a new alarm time. It will be described in Table 1 listed below how the alarm time changes in this case. Initial alarm time 1:59 When operating addition switch (K=0) 2:00 When first 1-Hz interrupt occurs (K=1. This moment is reference time S) 2:00 1 second after S (K=2) 2:01 2 seconds after S (K=3) 2:09 3 seconds after S (K=4) 2:17 5 seconds after S (K=6) 2:33 6 seconds after S (K=7) 3:53 7 seconds after S (K=8) 5:13 9 seconds after S (K=10) 7:53 10 seconds after S (K=11) 15:53 11 seconds after S (K=12) 23:53 As can be seen from this table, this embodiment is very effective in both of the case where a time being relatively close to the previously set initial time is set as the alarm time and the case where a time being relatively far away from the previously set initial time is set as the alarm time. Further, in the case of this embodiment, the selected setting-digit is shifted in sequence depending upon the period of time during which the switch is continuously operated. Thus, this embodiment is very convenient especially in the case where an operator wishes to set a date in addition to minutes and seconds by operating only one switch. Incidentally, in step 1020 of the flowchart of Fig. 10, it is preferable that, of the digits used to represent the alarm time, the digits whose orders are equal to or higher than the order of the selected digit, namely, the digits holding values which may be changed, continually display such values. In contrast, the digits having orders lower than the order of the selected setting digits are operated to blink, are turned off or are used to indicate arbitrary numerical values, symbols and characters. This is because there is no possibility of an occurrence of change in numerical value at the digits whose orders are less than the order of the selected digit, as digits, once selected as the setting digit are not selected again in this embodiment as long as the switch is continuously operated. Therefore, it is preferable for an operator that the manner of the display represented at each of the digits having orders lower than the order of the selected setting-digit is made to be different from that of the digits having orders equal to or higher than the order of the selected setting-digit. Further, in step 1020 of the aforementioned program, numerical values or the like may be simultaneously displayed at all of the digits. However, numerical values or the like may be displayed at the digits having orders equal to or higher than the order of the selected setting-digit at a frequency different from the frequency at which numerical values are displayed at the digits having orders lower than the order of the selected setting-digit. Fig. 11 is a flowchart of a program used to treat the display represented at each of the digits, the orders of which are equal to or higher than the order of the selected setting-digit, in a manner different from the manner in which the display represented at each of the digits, the orders of which are lower than the order of the selected setting-digit. The numerical values or the like at the digits having orders equal to or higher than the order of the selected setting-digit are displayed at a frequency different from the frequency at which numerical values are displayed at the digits having orders lower than the order of the selected setting-digit. In this case, the program illustrated in the flowchart of Fig. 10 is adapted to run in response to 1-Hz interrupts and 32-Hz interrupts. This program is executed at a frequency being four times the frequency at which the program previously described is executed. As shown in Fig. 11, numerical values or the like are displayed in step 1101 at the digits having orders lower than the order of the selected setting-digit, subsequent to the processing of step 1002 of the flowchart of Fig. 10. Next, an 8-Hz signal is read out. If the 8-Hz signal has an L-level (Low level), the program returns to step 1006 in order to perform the addition processing. Conversely, if the 8-Hz signal has a H-level (High level), the program finishes running. In accordance with this method, the display represented at each of the digits having orders lower than the order of the selected setting-digit varies at intervals corresponding to the clock frequency of 32Hz. However, the display represented at each of the digits having orders being equal to or higher than the order of the selected setting-digit varies at intervals corresponding to the clock frequency of 8Hz. Thus, an operator can easily distinguish the selected setting-digit from the other digits owing to the fact that the manner of the display represented at each of the digits having orders being equal to or higher than the order of the selected setting-digit is different from the manner of the display represented at each of the digits having orders being lower than the order of the selected setting-digit. Moreover, - because the frequency of change of the display at each of the digits having orders being lower than the order of the selected setting-digit is 32Hz and is thus high, an operator cannot know and need not mind what is displayed at each of these digits. Consequently, an operator can concentrate his attention on an operation of setting values at each of the digits having orders being equal to or higher than the order of the selected setting-digit. Further, although the manner of the display represented at each of the digits having orders lower than the order of the selected setting-digit is made to be different from that of the display represented at the digits having orders equal to or higher than the order of the selected setting-digit in the above embodiment, the display at the digits higher than the order of the selected setting-digit may be controlled similarly as in the case of the display at each of the digits having orders lower than the order of the selected setting-digit. The operator can then concentrate his attention on an operation of setting a value at the selected setting-digit alone. However, a carry may occur from the selected setting digit. Therefore, it is preferable that at least the manner of the display represented at each of the selected setting-digits, and the digit whose order is higher by one than the order of the selected setting-digit, is made to be different from the manner of the display represented at each of the other digits. Moreover, the arrangement may be such that when the selected setting-digit is changed, the alarm sounding means is used to inform an operator of the change of the selected setting-digit. In this embodiment, the alarm sounding means would sound every 4 seconds. This further improves the operability of the electronic clock. In this embodiment, the interruption processing is performed in response to each 16-Hz clock signal or each 8-Hz clock signal. The interruption processing, however, may be performed in response to clock signals, each of which has a frequency other than 8 and 16Hz. As long as the timing of interruptions is performed in such a manner that an operator perceives the advancement of the time to be smooth, and the time can be set accurately and quickly, there is no limitation imposed on the frequencies of clock signals. Preferably, clock signals having frequencies of 4 to 16Hz are used. If the frequency of interruptions is too low, the rate of advancement of the time or speed becomes too low. Thus it takes a long time to set the time. If the frequency of interruptions is too high, the rate or speed of change in numerical value displayed at each digit becomes too high. This increases the possibility of an operator inaccurately setting the time. It is, however, necessary to take into account the software processing time required to perform the additions or subtractions. Furthermore, if the frequency of interruptions is too high, a load imposed on software becomes very large. Therefore, it should be borne in mind that the necessary processing may not be completed within a cycle of the interrupt if the frequency is too high, and thus the advancement of the time cannot be achieved at a stable speed. Furthermore, in the arrangements described, the currently set time is incremented or decremented by using the two switches. The setting of the time, however, may be performed by using only one of the addition switch and the subtraction switch. Namely, the time is set by performing only increments (or the decrements). Incidentally, in this case, an operator needs to pay particular attention to the operation lest the currently set time should exceed a target alarm time. However, in the case of the electronic clock described errors in operation should rarely occur when setting a time compared with conventional methods for setting a time in an electronic clock. Additionally, in the arrangements described, the time setting method is applied to an alarm time. However, the application of the method of the present invention is not limited thereto. The time setting method of the present invention may be used to set, for example, a time indicated by a fundamental clock (the current time, a local time at each digit of the world, or the like) and a preselected time (an activating time/a stopping time of an electronic equipment interlinked with an electronic clock, for instance, a time preprogrammed in a timer, a time preprogrammed for sound/picture recording, or the like) other than an alarm time. The time setting method of the present invention can be applied to any electronic timepiece. In the case of the electronic clock described, the power consumption thereof may be relatively small and the configuration thereof is very simple. Therefore, the present invention can be applied most advantageously to portable electronic clocks such as a wristwatch and a pocket watch, which are driven by a battery and require a small-sized electronic circuit. Although the preferred embodiments of the present invention have been described above, it should be understood that the present invention is not limited thereto and that other modifications will be apparent to those skilled in the art.

Claims: An apparatus having a display (10) for displaying a value, and means (103, 104, 105) for adjusting at adjustment time intervals the value to be displayed in response to a user input such that the rate of adjustment varies over a period of time, characterised in that the variation of the rate of the adjustment is provided by varying the amount by which the value is incremented/decremented at the adjustment time intervals, and the amount by which the value is incremented/decremented at the adjustment time intervals is increased as the duration of the user input increases. An apparatus as claimed in claim 1, wherein the display comprises a plurality of display digits for displaying the value, and the value is incremented/decremented by selecting different ones of the display digits to have their values altered at different adjustment time intervals. An apparatus as claimed in claim 1 or 2, wherein the amount by which the value is incremented/decremented at the adjustment time intervals is initially set as ± 1 unit, and changes to ±2 n units (n=1, 2, 3,...), n increasing at regular time intervals as the duration of the user input increases. An apparatus as claimed in claim 1, 2 or 3, wherein the selected ones of the display digits are displayed such that they can be distinguished from the non-selected ones of the display digits. An apparatus as claimed in any one of the preceding claims, wherein the value displayed is a time. An apparatus as claimed in claim 5, wherein four display digits are provided which display tens of hours, hours, tens of minutes and minutes, respectively. An apparatus as claimed in any one of claims 1 to 6, wherein the apparatus is an electronic timepiece comprising: (a) a frequency divider means (101) for dividing down a frequency of a source oscillator and for generating a clock signal; (b) an input control means (102) for detecting a switch input signal to be used for setting a time; (c) an input time counting means (103) for counting a period of time during which the input control means detects a continuous input signal sent from the same switch by using the clock signal generated by the frequency divider means; (d) an input time detecting means (104) for detecting a fact that a value of the period measured by the input time counting means reaches a predetermined value; and (e) a setting increment/decrement control means (105) for establishing predetermined periods of time according to the clock signal generated by the frequency divider means and for varying a setting increment or decrement of a set value of a unit time to be added or subtracted each of the predetermined periods of time, which is formed using an output clock signal of the frequency divider means (101), according to an output of the input time detecting means. An apparatus as claimed in any one of claims 1 to 6, wherein the apparatus is an electronic timepiece comprising: (a) a frequency divider means (701) for dividing down a frequency of a source oscillator and for generating a clock signal; (b) an input control means (702) for detecting a switch input signal to be used for setting a time; (c) an input time counting means (703) for counting a period of time during which the input control means detects a continuous input signal sent from the same switch by using the clock signal generated by the frequency divider means; (d) an input time detecting means (704) for detecting a fact that a value of the period measured by the input time counting means reaches a predetermined value; and (e) a setting-digit selecting means (705) for selecting a time-setting-digit, at which a time is set, according to an output of the input time detecting means. A method of setting a value to be displayed, the method comprising adjusting at adjustment time intervals the value to be displayed in response to a user input such that the rate of adjustment varies over a period of time, characterised in that the variation of the rate of the adjustment is provided by varying the amount by which the value is incremented/decremented at the adjustment time intervals, and the amount by which the value is incremented/decremented at the adjustment time intervals is increased as the duration of the user input increases. The method as claimed in claim 9, wherein the method is a method for setting a time, comprising the steps of: counting a period of time, during which a switch input signal is continuously inputted, by using clock signals generated by a frequency divider means (101) which divides down a frequency of a source oscillator; and changing a set time by varying a set value of a unit time every predetermined constant period of time according to a counted value of the period of time.

Inventors: SAKAMOTO YUMI, SAKAMOTO, YUMI, SAKAMOTO, YUMI, C/O SEIKO EPSON CORPORATION
Applicants: SEIKO EPSON CORP, SEIKO EPSON CORPORATION
Application year: 1995
Main classification: G04G5
IPC codes: G04G1, G04G5