At present, large numbers of electronic timepieces are being manufactured, of various types and having various different functions. Digital and "combined analog-digital" timepieces are frequently provided with an alarm function, whereby the user can preset a desired time at which an alarm signal is to be generated. Such a function can be relatively easily and economically provided by using digital circuitry and a digital display device, for storing and displaying the preset alarm time. However in the case of an analog type of timepiece, i.e. a timepiece in which only time indicating hands are provided, it has not hitherto been practicable to provide an alarm function which can be set to a desired alarm time with a high degree of accuracy, such as is often available with relatively inexpensive digital timepieces. Various methods have been proposed and utilized to provide a relatively inaccurate alarm function in these analog electronic timepieces, for example by using an alarm time indicating hand or dial which is mechanically coupled to switch contacts. However such methods are not suited to high quality analog electronic timepieces. Another type of method which has been proposed for implementing an accurate alarm function in an analog electronic timepiece is to provide means whereby, when the user designates operation in an alarm time mode in which a preset alarm time is displayed, the timepiece hands are rapidly rotated through angles such that the alarm time is displayed. Subsequently, when the user designates return to the normal, i.e. current time display mode, then the hands are rotated into positions to display current time. However, as will be described hereinafter with reference to a specific example, prior art systems for implementing such an alarm function in an analog electronic timepiece present a number of serious disadvantages, including a possibility of errors being introduced into the current time information displayed by the timepiece, as a result of count errors occurring during the transitions between the alarm mode and the current time display mode. Such prior art systems also have the disadvantages of circuit complexity, whereby the size of timepiece integrated circuit chip is substantially increased, introducing design limitations, increased power consumption, and increased manufacturing cost. For these reasons, practical implementation of an alarm function of the type described above, utilizing a rapid advancement of the timepiece hands, has not yet been achieved.
With an alarm system for an analog electronic timepiece according to the present invention, the disadvantages of the prior art described above are eliminated. With an alarm system according to the present invention, the amount of circuitry required is substantially reduced by comparison with prior art proposals, as will be made clear in the specification, and introduction of time information errors during the transitions between current time display and alarm time display is completely eliminated. As a result, an alarm system for an analog electronic timepiece according to the present invention can be applied to practical manufacture of timepieces on a mass production basis, and enables the functional capabilities and hence the market appeal of such an analog electronic timepiece to be substantially increased.
Various other additional features can be provided with an analog electronic timepiece equipped with an alarm function according to the present invention as will be made clear by the description of the embodiments given hereinafter.
USPTO Backgrounds
USPTO Backgrounds