The invention relates to an electric timer with an analog time display and with a disk-or ring-shaped program carrier synchronously driven by a time-controlled clockwork and provided with slide contracts, which program carrier can be switched by means of a switching device from a speed of rotation of e.g. one revolution in 24 hours, corresponding to a short-term program, to a speed of rotation of e.g. one revolution in seven days, corresponding to a long-term program, and vice versa, and the slide contacts of which actuate a contact system, a scale ring corresponding to the set short-or long-term program being able to be selectively applied on the program carrier.
Electric timers of this kind, wherein for both programs, namely for a long-term or weekly program and for a short-term or daily program, one and the same program carrier is provided, are known.
In German Pat. No. 28 35 518 such a timer is disclosed in which the program carrier is firmly connected with the clockwork and is assigned to a single contact system. It can be set by a switchgear, e.g. to one revolution per week or to one revolution per day. The switchgear then consists of two gears of different rotational speed non-rotationally connected with the program carrier and arranged axially offset to each other and concentric with each other as well as concentric with the axis of the program carrier, as well as of two interconnected gears which are fixed on a drive shaft but are axially displaceable and which can be brought in engagement selectively with one or the other gear of the program carrier by axial displacement. Because the switching of the drive speed of the program carrier then occurs through axial displacement of two interconnected gears and it must be assured that in an intermediate position both of these displaceable gears must be simultaneously out of engagement with the two gears of the program carrier, there results in this known timer necessarily a relatively great axial overall height.
In this known timer it has also been known practice to reversibly place on the scale support a scale ring imprinted with scales on both sides, which indicates in each instance in time-correct manner the selected short-term or long-term program and with which it is possible also to set the scale support to the correct time of day or of the week. To avoid faulty switching that could result in a wrong clock time setting on the program carrier, this known timer has the switchgear provided with a barrier which permits switching only in certain time settings of the program carrier or respectively of the analog time display. This entails on the one hand additional cost of components and, on the other hand, additional complication in operating the timer.
Known from German Pat. No. 31 48 704 is a multirange switching device, in particular for timed switching devices, where a revolving switching or indexing disk is permanently connected with the timed switching device. To drive the disk at different speeds, two drive shafts are provided which by a coupling device can be selectively engaged with the disk. The coupling disk is disposed coaxial with the disk. To change the speed of the disk, the coupling device is reversible or displaceable axially. Upon change of the disk speed, the time scale of the short-term or long-term program arranged on the side opposite the engaged coupling device is visible. The scale support is then at the same time the coupling means. With this timer one and the same program carrier can indeed be used for both programs running at different speeds. But because of the necessity of reversing either the scale support as coupling means or the entire program carrier with the scale support and because of the action change connected therewith, there results not only a complicated and difficult handling of the switching means, but also, because of the non-indexing graduations of the interengaging coupling parts there occur in the one program errors and in the other time errors which cannot readily be avoided or eliminated. Besides, in this timer the central arrangement of a dial train with analog display is not possible.