DE3007908A1 - Electronic clock with auxiliary oscillator - has quartz oscillator which in event of mains supply failure is connected to time indicator - Google Patents

Abstract

The electronic clock for switching on radios, TV receivers, etc has a divider stage connected to the mains supply, to obtain a stable reference frequency. This is connected by a switch to the operating circuit for the clock, which is followed by a memory. The clock also has a quartz oscillator having a certain degree of stability, also connected to the switch. In the event of failure of the mains supply, the switch is operated so that the output of the quartz oscillator is entered into the memory. In an alternative, the circuit includes a more accurate quartz oscillator and a microprocessor.

Description

State of the art

The present invention relates to an electronic watch according to the Preamble of claim 1.

Such clocks can be found, for example, in consumer electronics devices such as clock radios and television receivers.

These clocks are reliable in terms of time display and Time evaluation in case of failure of the stable reference frequency could be improved.

The Invention and Its Advantages This is done in accordance with the present invention achieved in that the clock has a quartz oscillator of lower stability and if the stable clock frequency fails, that from the output signal of the crystal oscillator derived time is read into the memory.

Advantageous embodiment of the invention are that the Clock frequency via an automatic switch with the clock frequency input connected and the automatic switch automatically in the event of a clock frequency failure switches, so that the output of the crystal oscillator with the clock frequency input connected to the clock, whereby it is possible to determine the clock frequency from the mains frequency of the alternating current network, since the network frequency has a high long-term constancy having.

An advantageous further development of the invention, the use of Microprocessors enable time processing is that the clock has a having working according to a clock program microprocessor with a as Crystal oscillator formed with high stability and emitting the stable reference frequency Clock generator is connected to the stable reference from the microprocessor frequency-derived time to correct the low stability from the crystal oscillator derived and read into the memory time repeatedly read into the memory and after a failure of the microprocessor working according to the clock program that derived from the output signal of the low-stability crystal oscillator and time read into the memory by the microprocessor and read out by the Microprocessor as output time for the further from the microprocessor from the stable Reference frequency derived time is evaluated.

In order to ensure that a watch according to the invention is maintenance-free, it is advantageous to use the low-stability crystal oscillator from an accumulator battery to operate.

The advantages of an electronic watch according to the invention are in essential in that it has a simple structure and in particular with the help of standard modules such as integrated circuits lets, with the construction of an electronic watch according to the invention compared to a conventional electronic clock there is no significant additional expense.

DRAWING The invention is explained in more detail below with reference to FIGS. 1 and 2 explained.

FIG. 1 shows an electronic clock with the clock frequency input the clock if the clock frequency fails with the output of the crystal oscillator is lower Stability is connected.

Figure 2 shows an electronic watch according to the invention with a after a clock program working microprocessor.

At the input 13 of the electronic clock shown in FIG stands for example the network frequency of the AC network as a stable reference frequency at. The grid frequency is particularly suitable as a stable reference frequency, because it has a very high long-term stability despite its lower short-term stability. From the stable reference frequency present at the input 13, with the aid of, for example Trained as a divider level 12 derived the clock frequency of the electronic clock.

For this purpose, the clock frequency arrives via the automatic switch 3 the clock frequency input 4 of the clock circuit Thus from the stable clock frequency the time is derived and read into memory 2. The memory 2 becomes the time is read out and displayed with the aid of the display unit 8.

The automatic switch 3 can, for example, be a threshold value-dependent Be designed switch that the output of stage 12 as long as the clock frequency input 4 of the clock circuit 5 connects, as the level of the pending at input 13 stable reference frequency necessary for the clock to function properly Threshold exceeds, and this connection releases and the clock frequency input 4 of the clock circuit 5 with the output of the crystal oscillator 1 of lower stability connects when the level of the pending stable reference frequency at input 13 falls below the specified threshold. This cannot be explained in more detail in FIG. 1 illustrated control input of the automatic switch 3 with the input 13 in addition be connected. But it may also be sufficient to have the automatic switch 3 in his Switch position to be switched by the pulses that can be taken from stage 12.

The quartz oscillator 1 of lower stability is used here, for example consider an oscillator with a quartz crystal 14 of low temperature constancy, as it has, for example, a quartz oscillating at 32768 Hz. The quartz oscillator 1 can have prescaler stages.

The electronic watch according to the invention shown in FIG. 2 has a microprocessor 6 connected to its clock frequency generator 7. The clock generator 7 is designed as a high-stability crystal oscillator, the a quartz oscillating in the MHz range, for example, with a low temperature drift having. The microprocessor 6 is programmed so that he according to a clock program is working. The microprocessor 6 derives from the output signals of its clock generator 7 the exact time and reads it at regular intervals, for example several times into the memory 2 via the data line 9 within one second.

The electronic watch according to the invention shown in FIG. 2 also has a quartz oscillator 1 of low stability, which like the corresponding one Quartz oscillator 1 can be constructed in FIG. The crystal oscillator 1 is the clock circuit 5 downstream, with the one from the output signals of the quartz oscillator the time is derived. The time derived from the clock circuit 5 also becomes read into memory 2. The read from the clock circuit 5 into the memory 2 Time is constantly corrected by the microprocessor 6 in that it is as described the time derived from the output signals of the clock generator 7 at regular intervals Reads into memory 2 at intervals. Since the clock circuit 5 is the one in the memory 2 read in time, the next following time always from the time contained in memory 2 derives as a kind of counter reading, the one contained in the memory 2 is in this way Time and time displayed with the display unit continuously by the microprocessor 6 corrected.

If the microprocessor 6 working according to the clock program falls, for example due to a failure of the supply voltage, - so in the memory 2 only with the help of the clock circuit 5 from the output signals of the crystal oscillator 1 is read into the memory 2, so that the Clock in the event of a failure of the microprocessor 6 or the clock supply voltage continues.

At the beginning of the function of the microprocessor 6 after such Failure, the microprocessor 6 reads the data line 11 from the clock circuit 5 derived from the output signals of the crystal oscillator 1 and stored in the memory 2 read-in time from memory 2 and processes it as an output or output.

as the start time for his clock program, which again after the failure expires, so that the time without annoying time errors again from the highly stable Quartz oscillator 7 removable clock frequency is derived. The ones from the clock circuit 5 time read into memory 2 is restored by the microprocessor after failure 6 corrected in the manner described above by the microprocessor 6 from the the time derived from the output signals of the clock generator 7 at regular intervals reads into memory 2. The microprocessor is connected to the control line 10 connected to the memory 2.

Electronic clocks according to the invention, as they are for example in Figures 1 and 2 are shown, are particularly suitable for the construction of clocks operated from the alternating current network. In particular, according to the invention Use clocks in radio and television receivers, where these clocks are used as time switches can be used because they continue to work without annoying time errors even in the event of a power failure.

For this purpose it is advantageous to use the quartz oscillator with low stability to operate from an accumulator battery without interruption, the accumulator battery during the times when the clock is being fed from the AC mains is buffered with a small current to maintain the charge.

Electronic clocks designed according to the invention also bridge longer ones Power supply downtimes without disturbing deviations in the time display and in time evaluation.

Claims (5)

Electronic clock claims from one from a stable reference frequency derived clock frequency controlled electronic clock with high gag accuracy which reads the time derived from the stable clock frequency into a memory and is read from the memory for display by a display unit, characterized in that the clock has a quartz oscillator (1) of lower stability and in the event of a failure of the stable Taktfreuqenz from the output signal of the Quartz oscillator (1) derived time is read into the memory (2). 2. Electronic clock according to claim 1, characterized in that the clock frequency via an automatic switch (3) with the clock frequency input (4) the clock is connected and the automatic switch (3) if the clock frequency fails automatically switches over so that the output of the crystal oscillator (1) corresponds to the clock frequency input (4) the watch is connected. 3. Electronic clock according to claim 1, characterized in that the clock has a microprocessor (6) operating according to a clock program, the one designed as a quartz oscillator (7) of high stability and the stable one Clock generator emitting reference frequency is connected, those of that Microprocessor (6) derived from the stable reference frequency for correction time derived from the crystal oscillator (1) of low stability and stored in the memory (2) read-in time is repeatedly read into the memory (2) and after a Failure of the microprocessor (6) working according to the clock program from the output signal of the quartz oscillator (1) of low stability derived and stored in the memory (2) read in time by the microprocessor (6) and read out by the microprocessor (6) as the starting time for the next from the microprocessor (6) from the stable reference frequency derived time is evaluated. 4. Electronic clock according to claim 2, characterized in that the clock frequency is formed from the network frequency of the AC network. 5. Electronic clock according to one of claims 1 to 4, characterized in that that the crystal oscillator (1) of low stability from an accumulator battery is operated.