Time measuring device

Abstract

The invention relates to a timepiece (100), in particular a wristwatch, comprising an electro-optical converter device (1) with at least one electro-optical converter (10; 11, 12), an opto-electrical converter device (2), a first signal path (3) leading into the opto-electrical converter device (2) via a first waveguide (61), a second signal path (4) leading into the opto-electrical converter device (2) either directly or via a second waveguide (62), a control device (5) and a useful signal generating device (103). The first signal path (3) and the second signal path (4) are designed such that the propagation time of the first optical clock signal in the first signal path (3) and the propagation time of the second optical clock signal in the second signal path (4) are different from each other.

Description

[Technical field]

[0001] The present invention relates to a time measuring device. [Background technology]

[0002] From the prior art, quartz watches and automatic or hand-wound mechanical watches are known. Quartz watches keep time by the frequency of a crystal oscillator. Automatic mechanical watches (also called self-winding watches) and hand-wound mechanical watches, on the other hand, are generally controlled by the oscillations of a balance, which controls what is known as the escapement. Other time measuring devices, such as navigational instruments, are usually clocked in time by the frequency of a crystal oscillator, just like quartz watches. Summary of the Invention [Problem to be solved by the invention]

[0003] SUMMARY OF THEINVENTION It is an object of the present invention to provide a time measuring device which is as precise as possible. [Means for solving the problem]

[0004] The following describes a time measuring device comprising an electro-optical converter device having at least one or two parallel electro-optical converters, in particular an opto-electrical converter device having one or two parallel opto-electrical converters, a first signal path, a second signal path, a control device and a useful signal generating device.

[0005] The first signal path comprises a waveguide (referred to as the first waveguide) and leads from the electro-optical converter device through the waveguide into the opto-electrical converter device / photoelectric converter device, so that the first signal path may also comprise, at least in part, the opto-electrical converter device in addition to the waveguide.

[0006] The second signal path leads from the electro-optical converter device directly or via a second waveguide into the electro-optical converter device / electro-optical converter device, and thus comprises, at least in part, the electro-optical converter device and optionally the second waveguide.

[0007] The electro-optical converter device is configured to generate and feed a first clock optical signal into the waveguide and a second clock optical signal into the second signal path. The electro-optical converter device is configured to generate a first electrical signal based on the first clock optical signal and generate a second electrical signal based on the second clock optical signal. Furthermore, the first signal path and the second signal path are configured such that the transit time of the first clock optical signal in the first signal path and the transit time of the second clock optical signal in the second signal path are different from each other. In particular, based on the control signal, it is specified that two optical signals (first and second optical signals) with the same frequency and without phase shift are generated in the electro-optical converter device for the two signal paths. The two optical signals differ in phase shift only due to the difference in transit time in the two signal paths.

[0008] The control device is configured to generate a control signal based on a phase difference between the first electrical signal and the second electrical signal, and drive the electro-optical converter device with the control signal to generate two optical signals. Note that the control signal for controlling the electro-optical converter device corresponds to an output signal of the control device. In the context of the present invention, the control device may also be specifically referred to as a control unit.

[0009] The useful signal generator is configured to generate a useful signal for clocking time based on the frequency of the control signal.

[0010] According to an advantageous embodiment of the invention, the time measuring device can be a clock, in particular a wristwatch, with a clock display. In this case, the clock display is configured to display the time on the basis of a useful signal. According to a further advantageous embodiment of the invention, the time measuring device can be a navigation device time measuring device. The operating mode of the navigation device is based on time measurement, in particular on the measurement of the time it takes for a radio signal to reach the navigation device from at least three satellites. The more accurate the time measurement, the more accurate the position determination of the navigation device. If the time measuring device is not a clock, it can preferably comprise an application-oriented unit. The application-oriented unit can be implemented as software and / or hardware. If the time measuring device is a navigation device time measuring device, the application-oriented unit can be a position determining unit configured to determine the position of the navigation device with the useful signal as a comparison signal.

[0011] The time measuring device according to the invention has the advantage that the waveguide of the first signal path is a frequency determining element, in particular an exclusive frequency determining element. In other words, the frequency used as the frequency for the clock of the time measuring device (clock frequency) is in particular exclusively based on the transit time of light through the waveguide of the first signal path. This is achieved in particular by the provision of the above-mentioned second signal path and the control device. As a result, the less stable and less calculable signal delays caused by the electronic components of the time measuring device, in particular the electro-optical converter device and the opto-electrical converter device, have little or no influence on the clock frequency due to the light transit time in the waveguide. In particular, it is possible to exclude the response times of the electro-optical converter device and the opto-electrical converter device from the determination of the clock frequency. That is to say, in other words, the duration of the process of converting an electrical signal into an optical signal by the electro-optical converter device and also the duration of the process of converting an optical signal into an electrical signal by the opto-electrical converter device are not taken into account when determining the frequency associated with the clock of the time measuring device.

[0012] The advantage of an optically controlled time measuring device configured as a clock is that the generation of the clock pulses is independent of influences such as the movement and position (horizontal or vertical) of the watch. In particular, an optically controlled watch according to the invention is therefore significantly more accurate than a watch with a mechanical oscillator, in which the oscillations of the balance are suppressed or accelerated by the movement of the wearer's wrist, the tensioning of the clockwork spring influences the escapement and thus also the frequency of the balance / escapement tandem, and the position of the spring influences the oscillation characteristics of the balance. If the time measuring device is a navigational device time measuring device, the invention makes it possible to increase the accuracy of navigation compared to navigational devices with time measurement based on a quartz oscillator.

[0013] Furthermore, problems that arise in the case of time measuring devices with a frequency-determining oscillating crystal, for example deviations in the oscillation frequency caused by the ingress of impurities into the oscillating crystal over time or by other temporal circumstances, the so-called "aging" of the oscillating crystal, do not occur in the case of the proposed optically controlled time measuring device. Furthermore, the generation of clock pulses by a piezoelectric oscillating crystal, like the generation of clock pulses by a balance, is also based on mechanical vibrations, in particular on piezoelectrically excited mechanical vibrations of the oscillating crystal. Mechanical vibrations of this kind are more susceptible to damping than the clock optical signal in the proposed time measuring device. The optically controlled time measuring device according to the invention is therefore more accurate than a time measuring device in which clock pulses are generated by the vibrations of a piezoelectric oscillating crystal.

[0014] Furthermore, the optically controlled time measurement device according to the invention offers a high degree of flexibility with regard to the selection of the clock frequency of the time measurement device based on the light transit time in the waveguide of the first signal path as already explained. The clock frequency can be easily selected according to the respective requirements of the time measurement device and / or the design requirements of the owner / wearer of the time measurement device configured as a clock / watch. Thus, for example, it is possible to simply design the waveguide of the first signal path such that the clock frequency has a specific value.

[0015] The electro-optical converter device, the first signal path, the second signal path and the control device advantageously form a loop, in particular a control loop.

[0016] Advantageously, the time measuring device, in particular the useful signal generating device, can be equipped with an interface for reading out the frequency of the useful signal.

[0017] It will be appreciated that the first electrical signal and the second electrical signal are also advantageously clock signals, since the first optical signal and the second optical signal are clock signals.

[0018] The first and / or second optical clock signals may each in particular be an analog optical clock signal, in particular a sinusoidal optical signal. Correspondingly, the first and / or second electrical signal may each in particular be an analog electrical signal, in particular a sinusoidal electrical signal. However, shapes other than sinusoidal, for example rectangular, are also possible for said optical or electrical signals. Instead of an analog form, the first and / or second optical clock signal may each in particular be digital (pulsed). Correspondingly, the first and / or second electrical signal may each in particular be a digital (pulsed) electrical signal.

[0019] The control device preferably comprises a phase comparator, a loop filter (LF) for integrating an output signal of the phase comparator, and an oscillator drivable by the output signal of the loop filter, whereby the control signal for controlling the electro-optical converter device corresponds to or at least is based on the output signal of the drivable oscillator.

[0020] In the context of the present invention, a phase comparator may also be referred to as a phase frequency detector or a phase detector. The phase comparator is configured to compare the phase of a first electrical signal and the phase of a second electrical signal with each other and to output the phase difference therebetween as an output signal.

[0021] In particular, in the case of a pulsed electrical signal, the phase comparator is advantageously configured to generate an "up" signal and a "down" signal from an input first electrical pulse (first electrical signal) and an input second electrical pulse (second electrical signal), depending on which pulse is detected first.

[0022] The phase comparator preferably comprises a first input, a second input, a first, in particular a clock edge controlled D flip-flop (DFF), a second, in particular a clock edge controlled D flip-flop (DFF), and an AND gate. Each D flip-flop comprises a D input (set input), a Q output, a reset input ("reset") and a clock input. A high level is present at the D input of each D flip-flop. The first input is connected to the clock input of the first D flip-flop and to the first input of the AND gate, and the second input is connected to the clock input of the second D flip-flop and to the second input of the AND gate. The reset input of the first D flip-flop and the reset input of the second D flip-flop are connected to the output of the AND gate. The Q output of the first D flip-flop is connected to the Q output of the second D flip-flop by a subtractor. The clock input of the first D flip-flop and / or the clock input of the second D flip-flop are advantageously not inverted. In particular, each of the above mentioned connections, preferably each connection, is a direct connection, i.e. in particular no further elements are arranged between the elements interconnected in each case.

[0023] The loop filter is advantageously formed as an integrator arranged to integrate the output signal of the phase comparator and in particular convert it into a DC voltage. The greater the phase shift of the electric signals (first electric signal and second electric signal) input to the phase comparator, the higher the DC voltage generated by the loop filter for the subsequent drivable oscillator. Alternatively, the loop filter can advantageously be an arrangement consisting of an RC element or a charge pump and a capacitor. The topology of the loop filter does not depend on the type of drivable oscillator used. An RC element is understood to mean a circuit consisting of one or more ohmic resistors and one or more capacitors.

[0024] The drivable oscillator may preferably be a voltage controlled oscillator.

[0025] Alternatively, the drivable oscillator may comprise a tunable piezoelectric oscillating crystal, preferably with a trimmer capacitor configured to trim the piezoelectric oscillating crystal to a frequency resulting from the light transit time in the waveguide of the first signal path, meaning that the loop filter drives the trimmer capacitor, which sets the oscillation frequency of the piezoelectric oscillating crystal to a frequency corresponding to the light transit time in the first waveguide.

[0026] For this purpose, the length of the waveguide of the first signal path and the oscillation frequency of the piezoelectric oscillating crystal are pre-matched to one another. This matching is advantageously performed at a predefined temperature (also called target temperature). On the side of the waveguide of the first signal path, this can be done by measuring the length of the waveguide relative to the speed of light, so that for example the time it takes for an optical pulse to pass through the waveguide corresponds to the inverse of the planned oscillation frequency. At the same time, the cut of the piezoelectric oscillating crystal is measured so that the oscillation frequency (main frequency) at which the piezoelectric oscillating crystal oscillates corresponds to the planned value or substantially to the planned value. In other words, the piezoelectric oscillating crystal is cut so that it spontaneously oscillates at the same frequency as specified by the waveguide of the first signal path. For example, if the waveguide of the first signal path is configured to provide a frequency of 10 MHz for the first optical signal, the piezoelectric oscillating crystal is cut so that the oscillation frequency (main frequency) of the piezoelectric oscillating crystal is also 10 MHz.

[0027] The piezoelectric vibrating crystal is preferably a tourmaline crystal, although other piezoelectric vibrating crystals can also be used in combination with the trimmer capacitor, for example a quartz crystal can also be used here.

[0028] It is further advantageous if the trimmer capacitor can change the oscillation frequency of the piezoelectric oscillating crystal within the oscillation frequency range, so that in the case of a temperature change, the piezoelectric oscillating crystal still oscillates at a frequency resulting from the transit time of light in the waveguide. This means that for example in the case of a temperature change of 5° C., a frequency change of 80 Hz can occur in a tourmaline crystal configured as a piezoelectric oscillating crystal. However, due to the control loop, the entire arrangement always oscillates identically, or the frequency due to the temperature change also changes, but in a different way than the frequency of the tourmaline crystal changes. It is particularly advantageous if the tourmaline crystal is correspondingly controllable and allows a change of 80 Hz, since due to the control loop, the trimmer capacitor always reduces the tourmaline crystal to the frequency specified by the waveguide of the first signal path.

[0029] The trimmer capacitor may preferably be a varactor.

[0030] Advantageously, the control device can be implemented as hardware and / or software, i.e. the control device can be implemented completely as hardware or software or partly as hardware and partly as software.

[0031] The opto-electrical converter device preferably comprises a first opto-electrical converter and a second opto-electrical converter. In this case, the first signal path advantageously comprises a first opto-electrical converter and the second signal path comprises a second opto-electrical converter. The first opto-electrical converter is configured to generate a first electrical signal based on a first clock optical signal and the second opto-electrical converter is configured to generate a second electrical signal based on a second clock optical signal. An embodiment of the time measurement device comprising two opto-electrical converters has the advantage that the first electrical signal and the second electrical signal can be easily generated separately from each other. Advantageously, the first opto-electrical converter is configured identically to the second opto-electrical converter. In other words, the first opto-electrical converter and the second opto-electrical converter are preferably configured identically. This ensures that the response time of the first opto-electrical converter is identical to the response time of the second opto-electrical converter. As a result, it can be ensured that the magnitude of the signal delay caused by the first opto-electrical converter and the signal delay caused by the second opto-electrical converter are the same. Furthermore, this makes it possible to ensure that the light transit time in the waveguide of the first signal path is exclusively frequency deterministic, since said signal delays are mutually cancelled out by the control device.

[0032] Alternatively, the optoelectronic converter device comprises a single optoelectronic converter. The optoelectronic converter device is advantageously configured to convert the first clock optical signal into a first electrical signal and the second clock optical signal into a second electrical signal. For this purpose, the optoelectronic converter device comprises a signal splitter configured to receive the two optical signals from the two signal paths as a superimposed signal and to generate preferably a first electrical signal and a second electrical signal from the superimposed signal. In this variant, the first signal path may advantageously comprise a first waveguide, an optical splitter of the electro-optical converter device, a single optoelectronic converter and a first signal splitter signal path of the signal splitter. The second signal path may advantageously comprise a single optoelectronic converter and a second signal splitter signal path of the signal splitter. In this case, the optical splitter preferably comprises a semi-transparent mirror. Furthermore, in this case, the first waveguide of the first signal path may preferably be a single waveguide of the time measurement device.

[0033] According to a first advantageous embodiment of the invention, the electro-optical converter device comprises only a single electro-optical converter and an optical splitter. The single electro-optical converter is configured to generate a clock optical signal based on a control signal, and the optical splitter is configured to split the clock optical signal into a first clock optical signal and a second clock optical signal. By providing the electro-optical converter device with a single electro-optical converter, it is possible to provide a time measurement device for generating the first and second clock optical signals with a relatively low energy consumption. The optical splitter may preferably comprise a partially transparent mirror, in particular a partially transparent concave mirror.

[0034] According to a second advantageous embodiment of the invention, the electro-optical converter is a first electro-optical converter and the electro-optical converter device further comprises a second electro-optical converter. In other words, the electro-optical converter device of the second advantageous embodiment comprises two electro-optical converters. Both electro-optical converters are driven by one control signal, thereby generating optical signals, preferably of identical frequency and phase. In this case, the first electro-optical converter is configured to generate a first clock optical signal and the second electro-optical converter is configured to generate a second clock optical signal. By designing the electro-optical converter device with two electro-optical converters, the first and second optical signals can be provided without large technical expenditure. Furthermore, the quality of the first and second optical signals is guaranteed, since the two optical signals are generated separately from each other. Furthermore, it is possible to set the intensity of the two optical signals separately. In particular in time measuring devices where a sufficient power supply can be ensured, it is advantageous to provide two electro-optical converters.

[0035] According to an advantageous embodiment of the invention, the second optoelectronic converter can be arranged immediately next to the electro-optical converter device. In particular, the second optoelectronic converter can be directly connected to the electro-optical converter device. In another advantageous embodiment of the invention, the second waveguide of the second signal path can run parallel to the first waveguide of the first signal path. As a result, the electro-optical converter device, in particular the second electro-optical converter, is connected to the electro-optical converter device via the second waveguide. In this case, the second waveguide is preferably shorter than the first waveguide, in particular much shorter than the first waveguide. The first waveguide is preferably at least three times, preferably at least ten times, more preferably at least thirty times longer than the length of the waveguide of the second waveguide. It should be noted that the placement of the second waveguide does not depend on whether the electro-optical converter device comprises a single electro-optical converter or two electro-optical converters.

[0036] In the time measuring device according to the invention, the waveguide can be provided in an electro-optical converter arrangement with a first signal path and one or two electro-optical converters, or the waveguide can be provided in an electro-optical converter arrangement with a first signal path, a second optical signal path and one or two electro-optical converters. The decision whether to provide only one waveguide (the waveguide of the first signal path) or two and / or one or two electro-optical converters depends on the functional purpose or on certain predetermined parameters of the time measuring device, such as the maximum power consumption.

[0037] For better understanding, it should further be noted that in the case of an electro-optical converter device with a single electro-optical converter, the first clock optical signal and the second clock optical signal initially represent one single optical signal, in particular the above-mentioned clock optical signal. Said signal is generated and emitted by the single electro-optical converter and then split into two signal paths, namely the first signal path and the second signal path, by division by an optical splitter. In this case, the first signal path is advantageously understood to be frequency-deterministic. In contrast to the second signal path, the first signal path may comprise a waveguide (first waveguide) and the second signal path may be led directly into the electro-optical converter device. Alternatively, the second signal path may also comprise a waveguide (second waveguide), which is advantageously shorter than the waveguide of the first signal path. In this case, the first optical signal passes through a longer waveguide (first waveguide) of the first signal path, and the second optical signal passes through a shorter waveguide (second waveguide) of the second signal path. This means that the transit time of the first optical signal is longer than that of the second optical signal. Since both optical signals reach the control device, in particular the phase comparator, after passing through their respective waveguides and after conversion to corresponding electrical signals, the optical signal referred to as the "first clock optical signal" arrives later than the optical signal referred to as the "second clock optical signal". Thus, from a time point of view, the optical signal referred to as the "first clock optical signal" is actually the second signal, and the optical signal referred to as the "second clock optical signal" is actually the first signal when reaching the control device, in particular the phase comparator.

[0038] If the time measuring device comprises a first and a second waveguide, the first and second waveguides are preferably configured such that, at a predefined temperature (target temperature), the transit time of the first clock optical signal in the first waveguide and the transit time of the second clock optical signal in the second waveguide are different from each other. Furthermore, the first and second waveguides are preferably configured such that the change in transit time of the first clock optical signal in the first waveguide for a predefined temperature deviation from the predefined temperature is the same as the change in transit time of the second clock optical signal in the second waveguide for the same predefined temperature deviation (from the predefined temperature). In other words, the first and second waveguides are preferably configured such that, for any temperature change, they show exactly the same change in the transit duration of the respective optical signals through the corresponding waveguides. For example, if the temperature increases by 5°C from a given temperature, and the increase in temperature causes the time it takes for the first clock optical signal to traverse the first waveguide to increase by "n1" nanoseconds, the second waveguide will also experience an increase in the transit time of the second clock optical signal by "n1" nanoseconds for the same temperature increase. If the temperature decreases by, say, 2°C, and the first clock optical signal therefore traverses the first waveguide faster by "n2" nanoseconds, the transit time of the second clock optical signal through the second waveguide will also be shorter by "n2" nanoseconds.

[0039] This embodiment of the time measuring device not only allows the signal delays caused by the electro-optical and photoelectrical converter devices to be removed from the determination of the clock frequency of the time measuring device, as described above, but also allows temperature deviations from a given temperature that affect the light transit time in the first waveguide to be compensated for, so that the accuracy of the time measuring device can be guaranteed even in the case of temperatures that deviate from the given temperature.

[0040] It should be noted that the proposed temperature compensation may result in a more accurate clock of the time measurement device than a temperature compensation that measures the current temperature by a temperature sensor and adjusts the pulse counter (binary counter) based on the temperature deviation between the current temperature and a predetermined temperature. The reason is that it cannot always be guaranteed that the temperature sensor detects very accurately the temperature of the respective waveguide, especially the first waveguide, and / or the temperature of the surroundings of the respective waveguide, especially the first waveguide. Moreover, the adjustment of the pulse counter cannot be made correctly, since the temperature measurement itself may be affected by the changed temperature. Therefore, downstream electronic compensation by the pulse counter, where the frequency change set based on the temperature change is compensated, has the possibility of errors. For these reasons, temperature compensation on the waveguide side is more accurate.

[0041] Since the control device always exactly reproduces the frequency resulting from the time difference, or in other words the phase difference, between the first and second electrical signals, the frequency always remains the same whatever temperature variations are present and whatever time delays each waveguide results in, because in each case the time delay of the first waveguide resulting from the temperature variation is exactly the same as the time delay of the other waveguide. The difference between the two is always the same. Thus the frequency of the control signal output by the control device, in particular the drivable oscillator, is always the same despite any temperature variations.

[0042] It should be noted that the temperature around the respective waveguide and / or the temperature of the respective waveguide may be understood as temperature. The predetermined temperature corresponds in particular to the temperature at which the first waveguide is configured to enable a reference frequency to be achieved for the clock of the time measuring device. The predetermined temperature may in particular be 25°C. It should be noted that the temperature deviation is the temperature difference between the current temperature and the predetermined temperature. It should be further noted that in this case it is not necessary to measure the current temperature.

[0043] The main factors causing the change in the transit time of light in the waveguide in case of a temperature change, in this case the first and second waveguide in case of a temperature deviation from a predetermined temperature, are the longitudinal stretching of the waveguides seen from the respective expansion coefficients and the change in the speed of light due to the change in the refractive index in the respective waveguides. Thus, by purposefully selecting or setting the expansion coefficients and / or the refractive index of the first and / or second waveguide, the same change in the transit time of light in the first and second waveguide in case of a temperature deviation from a predetermined temperature can be achieved.

[0044] In this respect, the first and second waveguides differ from each other in particular in terms of the material and / or the length and / or the cross-sectional design through which the optical signal passes, where the second waveguide is in particular shorter than the first waveguide. By choosing the material and / or the length and / or the cross-sectional design through which the light passes of the first and / or second waveguide, the expansion coefficient and / or the refractive index of said waveguides can be set.

[0045] The coefficient of expansion of the first and / or second waveguide is preferably 0.41x10 -6 K -1 ~8x10 -6 K -1 It can be between.

[0046] In particular, the ratio between the expansion coefficients of the first and second waveguides may be between 1:30 and 1:4, in particular 1:16.

[0047] According to an advantageous embodiment of the invention, the first waveguide is configured as a hollow core fiber and the second waveguide is configured as a solid core fiber. In particular, the second waveguide can be a single mode fiber or a multimode fiber. In this case, the ratio of the expansion coefficient of the first waveguide to the expansion coefficient of the second waveguide is preferably 1:16.

[0048] As already explained, the response of the transit time of light through a waveguide to a change in temperature is determined not only by the change in the length of the waveguide, but also at least by the change in the refractive index of the optical waveguide material. Thus, a change in the speed of light through, for example, pure glass, will cause a very large time delay compared to a longitudinal stretch of the waveguide due to the changed refractive index. The change in the refractive index of air with temperature, on the other hand, is very small. This leads to a very large difference between the response of a hollow-core fiber to a change in temperature and the response of a solid-core fiber, i.e., for example, a single-mode fiber or a multimode fiber.

[0049] Because hollow-core fibers are typically made from pure silica glass that is not doped with germanium, while solid-core fibers are typically doped with germanium, the difference in the expansion coefficient between the two fiber types is significant (the expansion coefficient of hollow-core fibers is approximately 0.41x10 -6 whereas the expansion coefficient of a solid-core fiber is about 8x10 -6 Because both the expansion coefficient and the change in the refractive index lead to an increase in the transit time of light through the waveguide with increasing temperature, and because both the expansion and the change in the refractive index have a much larger effect in the solid-core fiber than in the hollow-core fiber, there is a very large difference in the transit time change with temperature for the two fiber types.

[0050] This serves to make the first and second waveguides oppose each other by a control device, in particular a phase comparator. In the end, only the difference between the two waveguides remains as the frequency-determining optical waveguide. However, since the length of the waveguides is very decisive for the accuracy of the time measurement device, if possible, the second waveguide should be as short as possible and the first waveguide as long as possible. To achieve this, the ratio of the responses to temperature changes should be as large as possible, since the ratio of the lengths of the two waveguides should be proportional to the ratio of the responses to temperature changes.

[0051] Furthermore, to simplify the handling of this temperature compensation method, we note that the response to temperature changes (due to longitudinal stretch and refractive index change) should scale linearly for both fiber types.

[0052] Temperature compensation on the waveguide side is also possible by heating the first and / or second waveguide in such a way that a change in temperature of the first and / or second waveguide and thus in the light transit time in the respective waveguide is prevented if a drop in the current temperature is detected. However, heating the first and / or second waveguide can be very complicated and consume a lot of power, and there is a risk that the heating devices used for this purpose are not absolutely perfect and thus give rise to a certain inaccuracy of the time measuring device itself.

[0053] Preferably, a reflector is arranged at the reflecting end of the waveguide of the first signal path (first waveguide), by which the first clock optical signal can be reflected into the waveguide of the first signal path. In this case, the first signal path is configured in such a way that the reflected first clock optical signal can be output into a first opto-electrical converter at the supply end of the waveguide of the first signal path. Thus, for a constant length of the waveguide of the first signal path, the path that the light has to travel before being acquired by the opto-electrical converter device is doubled. Thus, the desired reference frequency for the clock of the time measurement device can be achieved with a more compact design of the time measurement device. Furthermore, as a result, the cost of the waveguide of the first signal path and thus of the time measurement device can be reduced. This is particularly advantageous in terms of the accuracy of the time measurement device when the waveguide of the first signal path is configured as a hollow core fiber, because hollow core fibers are very laborious to manufacture or provide. For example, a hollow core fiber with a length of 20 m would account for more than 95% of the total cost of the time measurement device. Therefore, by providing a reflector at the reflective end of the waveguide of the first signal path, the cost of the time measurement device can be reduced by approximately 50%.

[0054] The reflector is preferably configured as a concave mirror. In this case, the concave mirror is advantageously configured to recollimate the divergent light emerging from the waveguide. In particular, the concave mirror can be a spherical concave mirror. However, the reflector can also be other types of mirrors, particularly suitable for reflecting the optical signal emerging at the reflecting end. According to another advantageous embodiment of the invention, the reflector can be configured as a plane mirror arranged directly above the reflecting end, i.e. the corresponding output of the corresponding waveguide. For this purpose, an end cap can be advantageously arranged directly above the reflecting end of the waveguide, the inner surface of this end cap being mirrored, i.e. the surface of the end cap facing the reflecting end of the waveguide. This ensures that little or no light is lost after reflection. The embodiment of the invention with a mirrored end cap has the further advantage that separate parts and associated adjustments can be omitted, for example when a separate end cap is arranged at the reflecting end in addition to the concave mirror.

[0055] The first signal path preferably comprises an optical splitter at a supply end of the waveguide, the splitter configured to output the reflected first optical clock signal into the first optoelectronic converter, the optical splitter preferably comprising a semi-transparent mirror or a fiber splitter.

[0056] Preferably, the electro-optical converter device may further comprise a lens between the light splitter and the electro-optical converter. The lens is in particular configured to refract the light emitted by the electro-optical converter in such a way that the light propagates in a parallel direction. For this purpose, a focusing lens may advantageously be used. In this case, the focus of the focusing lens is advantageously located at the point from which the light generated by the electro-optical converter is emitted. However, the lens may also be configured to collect the divergent light emitted by the electro-optical converter and to focus it in particular in the center of the first waveguide.

[0057] In the context of the present invention, a lens may advantageously comprise a single lens element or an optical system comprising at least two lens elements.

[0058] Preferably, each electro-optical converter of the electro-optical converter device comprises a semiconductor laser or a light-emitting diode. That is, in the above-mentioned embodiment of the time measuring device, the single electro-optical converter or the first electro-optical converter and / or the second electro-optical converter of the electro-optical converter device respectively comprises a semiconductor laser or a light-emitting diode. The semiconductor laser can in particular be a pigtailed semiconductor laser. Correspondingly, the light-emitting diode can be a pigtailed light-emitting diode.

[0059] Preferably, each optical-to-electrical converter comprises a photodiode configured to convert a corresponding optical clock signal into a corresponding electrical signal.

[0060] In the context of the present invention, the useful signal generating device may also be referred to as an electronic useful signal generating device.

[0061] To generate the above-mentioned useful signal, the useful signal generator can preferably comprise a pulse counter (binary counter). In this case, the pulse generator is advantageously configured to count the control signal. In this case, the useful signal generator is advantageously configured to generate the useful signal when the count value of the control signal is equal to a predefined count value. The predefined count value is advantageously set to a frequency based on the light transit time in the waveguide of the first signal path.

[0062] Alternatively, in order to generate the above-mentioned useful signal, the useful signal generating device can advantageously comprise a frequency divider. The frequency divider is configured to divide the frequency of the control signal. In this case, the useful signal advantageously corresponds to the output signal of the frequency divider. In this case, the frequency of the control signal can in particular correspond to a multiple of 2, in particular a power of 2, for example 524288 Hz or 1048576 Hz. In this case, the frequency of the control signal can advantageously be resolved by the frequency divider into other frequencies, such as 1 Hz or 8 Hz. The resolved frequency corresponds to the useful signal, on the basis of which the clock display device displays the time, for example in the case of a time measuring device configured as a clock. It should be noted that in the case of a useful signal having a frequency of, for example, 8 Hz, the jumps of the second hand of a mechanical clock display device occur 8 times per second, and are therefore no longer perceived as "jumps" by the observer.

[0063] A combination of a frequency divider and a pulse counter is also possible to generate the useful signal. In this case, the frequency divider is advantageously arranged in front of the pulse counter in terms of the signal. In an advantageous manner, the frequency of the control signal can be halved in a first step by the frequency divider, in particular multiple times, to achieve an intermediate frequency. In a second step, the intermediate frequency can be brought to the desired or useful frequency by the pulse counter. In this case, the useful signal generator is advantageously configured to generate the useful signal when the count value of the output signal of the frequency divider is equal to a predefined count value. In this case, the predefined count value is advantageously set on the basis of the intermediate frequency achieved by the frequency divider. The approach of halving the frequency of the oscillating crystal in a first step, in particular multiple times, to achieve an intermediate frequency, and counting down the intermediate frequency to the desired frequency in a second step is particularly advantageous in the case of time measuring devices in which the control signal has a high frequency, for example 8.88 MHz or 10 MHz. In this way, power can be saved compared to simply counting down the frequency of the control signal.

[0064] If the control signal is analog, the useful signal generating device preferably comprises a device for converting the analog control signal into a digital signal.

[0065] According to an advantageous embodiment of the time measuring device configured as a clock, the clock display is a mechanical clock display. In this case, the clock preferably comprises a drive that can move the mechanical clock display. In this case, the drive can preferably be driven by a useful signal. In particular, the clock display can comprise an hour hand and / or a minute hand and / or a second hand.

[0066] Advantageously, the timepiece may further comprise a clockwork. In this case, the drive device is adapted to drive the clockwork. The timepiece display device is connected to the clockwork and can be driven by the clockwork. The clockwork preferably comprises at least an hour wheel and / or a minute wheel and / or a second wheel, and / or a third wheel.

[0067] The drive is preferably configured as a stepper motor.

[0068] According to an advantageous embodiment of the time measuring device configured as a clock, the clock display is an electronic clock display which is configured to display the time on the basis of the useful signal.

[0069] Furthermore, the time measuring device preferably comprises a power supply device configured to supply power to the electro-optical converter device and / or the control device and / or the useful signal generating device and / or the drive device and / or the clock display device when the time measuring device is configured as a clock and / or as an electronic clock display device.

[0070] The power supply unit may preferably comprise at least one battery. The at least one battery may preferably be charged by the energy harvesting device. The energy harvesting device may preferably comprise at least one thermoelectric generator and / or at least one solar cell. The thermoelectric generator may in particular comprise one or more thermoelectric elements.

[0071] It should be noted that in the context of the present invention, the first signal path waveguide may also be referred to as a first waveguide even if the time measurement device comprises only a single waveguide called the first signal path waveguide.

[0072] Further details, advantages and features of the invention will become apparent from the following description of embodiments with reference to the attached drawings, in which identical or functionally identical components are in each case designated with the same reference signs. [Brief description of the drawings]

[0073] [Figure 1] FIG. 1 is a simplified schematic diagram of a time measurement device according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a simplified schematic diagram of an area of ​​a time measuring device according to a first embodiment. [Diagram 3] FIG. 3 is a circuit diagram of a phase comparator of the time measurement device according to the first embodiment. [Figure 4] FIG. 4 is a flow diagram of the phase comparator of FIG. [Diagram 5] FIG. 5 is a simplified schematic diagram of an area of ​​a time measuring device according to a second embodiment of the invention. [Figure 6] FIG. 6 is a simplified schematic diagram of an area of ​​a time measuring device according to a third embodiment of the invention. [Figure 7] FIG. 7 is a simplified schematic diagram of an area of ​​a time measuring device according to a fourth embodiment of the invention. [Figure 8] FIG. 8 is a simplified schematic diagram of an area of ​​a time measuring device according to a fifth embodiment of the invention. [Figure 9] FIG. 9 is a simplified schematic diagram of an area of ​​a time measuring device according to a sixth embodiment of the invention. [Figure 10] FIG. 10 is a simplified schematic diagram of an area of ​​a time measuring device according to a seventh embodiment of the invention. [Figure 11] FIG. 11 is a simplified schematic diagram of an area of ​​a time measuring device according to an eighth embodiment of the present invention. [Figure 12]FIG. 12 is a simplified schematic diagram of an area of ​​a time measuring device according to a ninth embodiment of the present invention. [Figure 13] FIG. 13 is a simplified schematic diagram of an area of ​​a time measuring device according to a tenth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0074] Hereinafter, a time measurement device 100 according to a first embodiment of the present invention will be described in detail with reference to FIGS.

[0075] As is evident from figure 1, the time measuring device 100 is configured as a clock, in particular a wristwatch, and therefore comprises two connections 140 for a wristband 160. However, the time measuring device 100 can also be a wall clock, a floor clock, a table clock or any other kind of table clock.

[0076] The time measuring device 100 further comprises a watch case 110, a timepiece crystal 150 arranged therein, a dial 120, a wheel 170 and three hands 130 for displaying hours, minutes and seconds. The hands 130 are part of a mechanical timepiece display 106 for displaying the time of day.

[0077] Furthermore, the time measuring device 100 comprises a timing generator assembly 101, a clockwork 105 and a drive device 104 for driving the clockwork 105. The drive device 104 is in particular configured as a stepper motor. The clockwork 105 is connected to a mechanical clock display 106 for moving hands 130 of the clock display 106. In particular, the clockwork 105 comprises at least an hour indicator, a minute indicator and a second indicator, each of which is connected to one of the hands 130.

[0078] The timing generator assembly 101 is configured to determine a frequency associated with the clock of the time measurement device 100. Part of the timing generator assembly 101 is a useful signal generating device 103 configured to generate a useful signal for clocking the time based on the frequency of a control signal. For this purpose, the useful signal generating device 103 may comprise a pulse counter. If the control signal is an analog signal, a device may be provided in the useful signal generating device 103 for converting the analog control signal into a digital (pulsed) signal.

[0079] The drive unit 104 is driven based on the useful signal and runs the clockwork 105 .

[0080] From Fig. 2 it can be seen that the time measurement device 100 further comprises an electro-optical converter device 1, an opto-electrical converter device 2, a first signal path 3, a second signal path 4 and a control unit 5. These components are part of a timing generator assembly 101 and form an oscillator system 102. In this embodiment, the opto-electrical converter device 2 comprises a first opto-electrical converter 21 and a second opto-electrical converter 22. The first opto-electrical converter 21 and / or the second opto-electrical converter 22 may each comprise a photodiode.

[0081] The first signal path 3 comprises a waveguide (first waveguide) 61, and runs from the electro-optical converter device 1 to the opto-electrical converter device 2 via the waveguide 61. As a result, the first signal path 3 comprises, in addition to the waveguide 61, a first opto-electrical converter 21. The second signal path 4 runs from the electro-optical converter device 1 to the opto-electrical converter device 2, and thus comprises a second opto-electrical converter 22. Thus, the first signal path 3 and the second signal path 4 each comprise the opto-electrical converter device 2 as a part thereof.

[0082] The electro-optical converter device 1 is configured to provide a first clock optical signal in a first signal path 3, in particular in the waveguide 61, and a second clock optical signal in a second signal path 4. To this end, the electro-optical converter device 1 comprises a single electro-optical converter 10 and an optical splitter 13. The electro-optical converter 10, which may in particular comprise a semiconductor laser or a light-emitting diode, is configured to generate a clock optical signal. In this case, the optical splitter 13 is configured to split the clock optical signal that may be generated by the electro-optical converter 10 into a first clock optical signal and a second clock optical signal.

[0083] The optical-to-electrical converter device 2 is capable of generating a first electrical signal based on a first clock optical signal and generating a second electrical signal based on a second clock optical signal. In particular, the first optical-to-electrical converter 21 is configured to generate the first electrical signal and the second optical-to-electrical converter 22 is configured to generate the second electrical signal.

[0084] The first opto-electrical converter 21 and the second opto-electrical converter 22 are advantageously constructed identically. In other words, the two opto-electrical converters 21, 22 are structurally identical and the signal delay caused by the first opto-electrical converter 21 is the same as the signal delay caused by the second opto-electrical converter 22. In this case, the second opto-electrical converter 22 is arranged immediately after the electro-optical converter device 1, in particular the optical splitter 13. In particular, the second opto-electrical converter 22 is directly connected to the optical splitter 13. It should be noted at this point that in this embodiment, for the sake of illustration, the direct connection between the second opto-electrical converter 22 and the optical splitter 13 is shown by a line.

[0085] Thus, the first signal path 3 and the second signal path 4 are configured such that the transit time of the first clock optical signal in the first signal path 3 and the transit time of the second clock optical signal in the second signal path 4 are different from each other. In particular, due to the structurally identical opto-electrical converters 21, 22, the transit time of the first clock optical signal in the first signal path 3 differs from the transit time of the second clock optical signal in the second signal path 4 by the transit time of the first clock optical signal in the waveguide 61.

[0086] However, according to a variant of the first embodiment, it is also possible to configure the first opto-electrical converter 21 and the second opto-electrical converter 22 differently and / or to connect the electro-optical converter 10 to the second opto-electrical converter 22 via a waveguide. In the latter case, the waveguide is part of the second signal path 4. In this case, the waveguide of the second signal path 4 is shorter, in particular much shorter, than the waveguide 61 of the first signal path 3. In this case, the waveguide 61 of the first signal path 3 is preferably at least 10 times, preferably at least 30 times, longer than the length of the waveguide of the second signal path 4. In this embodiment, the waveguide 61 of the first signal path 3 can be referred to as the first waveguide and the waveguide of the second signal path 4 can be referred to as the second waveguide.

[0087] The control device 5 is configured to generate the above-mentioned control signal based on the phase difference between the first electrical signal and the second electrical signal, generate a useful signal by the useful signal generating device 103 based on the frequency of this control signal, and control the electro-optical converter device 1 by said useful signal to generate two optical signals.

[0088] In particular, it is provided that for the two signal paths 3, 4, two optical signals (first and second optical signals) with the same frequency and without phase shift are generated in the electro-optical converter device 1 based on the control signal. The two optical signals differ in phase shift only due to the difference in transit times in the two signal paths 3, 4.

[0089] For this purpose, the control device 5 includes a phase comparator 50 , a loop filter 51 for integrating the output signal of the phase comparator 50 , and an oscillator 52 that can be driven by the output signal of the loop filter 51 .

[0090] The phase comparator 50 has a first input 501 and a second input 502. The first input 501 is arranged to receive a first electrical signal and the second input 502 is arranged to receive a second electrical signal. For this purpose, the first input 501 is connected to the first optical-to-electrical converter 21 and the second input 502 is connected to the second optical-to-electrical converter 22. The phase comparator 50 is arranged to compare the phase of the first electrical signal with the phase of the second electrical signal with respect to each other and to output the resulting phase difference between them as an output signal. The exact design and mode of operation of the phase comparator 50 will be explained in more detail later with reference to figures 3 and 4.

[0091] The loop filter 51 is advantageously formed as an integrator arranged to integrate the output signal of the phase comparator 50 and convert it into a DC voltage. Alternatively, an arrangement consisting of an RC element or a charge pump and a capacitor can be used as the loop filter 51. The greater the difference between the time duration of the input first electrical signal and the time duration of the input second electrical signal, the higher the DC voltage generated by the loop filter 51 for the subsequent drivable oscillator 52.

[0092] The drivable oscillator 52 is configured as a voltage controlled oscillator (VCO). Alternatively, the drivable oscillator 52 can comprise a tunable piezoelectric oscillating crystal with a trimmer capacitor. In this case, the trimmer capacitor can in particular be configured as a varactor. Preferably, a tourmaline crystal can be used as the piezoelectric oscillating crystal.

[0093] The output signal of the drivable oscillator 52 corresponds to or at least is based on a control signal for controlling the electro-optical converter device 1 , in particular the electro-optical converter 10 .

[0094] Depending on the application or embodiment of the time measurement device 100, the control device 5 can be implemented as hardware and / or software, i.e., the components of the control device 5 are implemented exclusively as software or hardware, or the control device 5 is configured as a combination of hardware and software.

[0095] To supply power to the electro-optical converter device 1, the control device 5, the useful signal generating device 103 and the driving device 104, the time measuring device 100 comprises a power supply device.

[0096] The power supply unit may comprise at least one battery, which may preferably be charged by at least one thermoelectric generator and / or an energy harvesting unit comprising at least a solar cell.

[0097] A control loop, in particular a phase-locked loop, is formed by the electro-optical converter device 1, the first signal path 3, the second signal path 4, the photoelectric converter device 2, and the controller 5 in signal connection with the electro-optical converter device 1. That is, the above-mentioned oscillation system 102 is configured as a control loop, in particular a phase-locked loop.

[0098] The control loop engages the frequency of the control signal with which the electro-optical converter 10 is clocked, thereby making it possible to freeze the frequency of the oscillating system 102 at a constant value. In particular, the control loop makes it possible to engage the output signal of the drivable oscillator 52 with the input signal of the phase comparator 50, thereby ensuring a constant and always identical frequency of the oscillating system 102 which serves as the starting point for the clock of the time measuring device 100.

[0099] 3 is a circuit diagram showing the exact design of phase comparator 50. FIG.

[0100] From FIG. 3 it can be seen that the phase comparator 50 comprises a first input 501, a second input 502, a first, in particular a clock edge controlled D flip-flop (DFF) 53, a second, in particular a clock edge controlled D flip-flop (DFF) 54 and an AND gate 55.

[0101] The first D flip-flop 53 has a D input (set input) 531, a Q output 534, a reset input 533 ("reset"), and a non-inverting clock input 532. Correspondingly, the second D flip-flop 54 has a D input (set input) 541, a Q output 544, a reset input 543 ("reset"), and a non-inverting clock input 542. The clock inputs 532, 542 each respond only to positive (rising) signal edges.

[0102] A high level is present at the D input 531 of the first D flip-flop 53. A first input 501 of the phase comparator 50 is connected to the clock input 532 of the first D flip-flop 53 and to a first input 551 of the AND gate 55, and a second input 502 of the phase comparator 50 is connected to the clock input 542 of the second D flip-flop 54 and to a second input 552 of the AND gate 55. A reset input 533 of the first D flip-flop 53 and a reset input 543 of the second D flip-flop 54 are connected to an output 553 of the AND gate 55. A Q output 534 of the first D flip-flop 53 is connected to a Q output 544 of the second D flip-flop 54 by a subtractor 56. In particular, the described connections are direct connections, i.e. without connecting further components between the respective interconnected components.

[0103] The label "REF" in the circuit diagram of FIG. 3 represents a "reference signal" corresponding to the first electrical signal. The label "VCO" stands for "voltage controlled oscillator" and indicates a VCO signal corresponding to the second electrical signal. The label "PD" stands for "phase difference" and corresponds to the output signal of phase comparator 50. "reset" represents a reset signal, "up" represents an up signal, and "down" represents a down signal. The up signal corresponds to the output signal of first D flip-flop 53, and the down signal corresponds to the output signal of second D flip-flop 54.

[0104] The mode of operation of phase comparator 50 is now explained with reference to the flow diagram of FIG.

[0105] For a first rising edge of the VCO signal (second electrical signal), the second (lower) D flip-flop 54 captures the high level at its D input 541 and sets the Q output 544 of the second D flip-flop 54 to a high level, resulting in the Down signal going "high" (arrow 201).

[0106] After an optical delay time in the waveguide 61 of the first signal path 3, a rising edge appears at the first input 501, also called the REF input, of the phase comparator 50, causing the first (upper) D flip-flop 53 to also see a high level at its D input 531 and set the Up signal to “high” at its Q output 534 (arrow 202).

[0107] In contrast to a conventional phase comparator 50 in which a reset of the flip-flops occurs when both output signals of the flip-flops are "high", in the phase comparator 50 of Figure 3, the first D flip-flop 53 and the second D flip-flop 54 are reset when both input signals of the phase comparator 50, i.e., the VCO signal and the REF signal, are "high". However, the VCO signal goes "low" again before the rising edge of the REF signal reaches the phase comparator 50.

[0108] Thus, the reset of the two D flip-flops 53, 54 occurs only after the next edge of the VCO signal goes "high" again. At this point, the REF signal is also still "high" and a reset signal is generated (arrow 203).

[0109] The down signal (arrow 204) and the up signal (arrow 205) are reset by the reset signal. Since the first down pulse is longer than the up pulse, the result is that only one incorrect signal reaches the loop filter 51 following the phase comparator 50. However, due to the large time constant of the control, a single incorrect pulse is not significant.

[0110] The modified reset is followed by a next rising edge at the first input 501 (REF input) of the phase comparator 50, which causes the UP signal to go "high" (arrow 206).

[0111] The subsequent rising edge of the VCO signal also sets the DOWN signal momentarily "high" (arrow 207). Because both the REF signal and the VCO signal, i.e., both inputs of AND gate 55, are now "high" (arrow 208), a RESET signal appears at the output 553 of AND gate 55, resetting both the DOWN signal (arrow 209) and the UP signal (arrow 210).

[0112] The up signal is high for a longer period of time than the down signal, resulting in an increase in the frequency of the drivable oscillator 52. This is repeated in the same manner for the next cycle until the drivable oscillator 52 is engaged at the desired frequency.

[0113] The described circuitry ensures without any problems the temporal reordering of the incoming electrical signals, in particular the first and second electrical signals, that can be generated by the two opto-electrical converters 21, 22. The phase comparator 50 therefore makes it possible to engage the control loop at a self-generated frequency. In particular, the described circuitry of the phase comparator 50 is advantageous when the period T=1 / f of the VCO signal at the start (after ON) is greater than the transit time of the first electrical signal in the waveguide 61 of the first signal path 3. If the period T=1 / f of the VCO signal at the start (after ON) is not greater than the transit time of the first electrical signal in the waveguide 61 of the first signal path 3, a conventional phase comparator can also be used for the phase comparator 50.

[0114] The proposed time measuring device 100 configured as a clock has the advantage, in particular, that the oscillating system 102 is free from delays due to electronic components and that the frequency of the oscillating system 102 associated with the clock of the time measuring device 100 depends in principle, in particular exclusively, on the duration of the travel of the first clock optical signal through the waveguide 61 of the first signal path 3 or on the speed of light in the waveguide 61 of the first signal path 3 and the length of the waveguide 61.

[0115] FIG. 5 relates to a time measuring device 100 configured as a clock according to a second embodiment of the invention.

[0116] The time measurement device 100 according to the second embodiment differs from the time measurement device 100 according to the first embodiment by the following design of the oscillation system 102 .

[0117] In this case, the first signal path 3 comprises a first waveguide 61 and the second signal path 4 comprises a second waveguide 62. That is to say, the electro-optical converter device 1 is connected to the first opto-electrical converter 21 via the first waveguide 61 and to the second opto-electrical converter 22 via the second waveguide 62. In contrast to the time measuring device 100 according to the first embodiment, in which there is in particular a direct connection between the optical splitter 13 of the electro-optical converter device 1 and the second opto-electrical converter 22, the second opto-electrical converter 22 is connected to the optical splitter 13 of the electro-optical converter device 1 via the second waveguide 62. The first waveguide 61 and the second waveguide 62 can in particular run parallel to each other.

[0118] The first waveguide 61 and the second waveguide 62 are configured such that, at a given temperature, the transit time of the first optical clock signal in the first waveguide 61 and the transit time of the second optical clock signal in the second waveguide 62 are different from each other.

[0119] Furthermore, the first waveguide 61 and the second waveguide 62 are configured such that the change in transit time of the first clock optical signal in the first waveguide 61 for a given temperature deviation from a given temperature is the same as the change in transit time of the second clock optical signal in the second waveguide 62 for the same given temperature deviation. This means that if the transit time of the first clock optical signal increases by 'n' nanoseconds due to a temperature change for example, the second waveguide 62 is configured such that for the same temperature change the transit time of the second clock optical signal in the second waveguide 62 also increases by 'n' nanoseconds.

[0120] For this purpose, the first waveguide 61 and the second waveguide 62 can differ in terms of the material through which light can pass and / or the length and / or the cross-sectional design. In this case, the second waveguide 62 is shorter than the first waveguide 61. In this case, the first waveguide 61 is preferably at least 10 times, preferably at least 30 times, longer than the waveguide length of the second waveguide 62.

[0121] In particular, the first waveguide 61 can be configured as a hollow core fiber and the second waveguide 62 can be configured as a solid core fiber. In this case, in particular, the second waveguide 62 can be a single mode fiber or a multimode fiber. In this case, the ratio of the expansion coefficient of the first waveguide 61 to the expansion coefficient of the second waveguide 62 can be between 1:30 and 1:4, in particular 1:16.

[0122] The time measuring device 100 according to the second embodiment configured as a clock has the advantage that it is possible to compensate for temperature changes in the first waveguide 61, which in particular lead to changes in the original length and the refractive index of the first waveguide 61. In particular, this makes it possible to dispense with a temperature sensor and a readjustment of the frequency specification for the pulse counter of the useful signal generating device 103, so that measurement inaccuracies can be eliminated.

[0123] FIG. 6 relates to a time measuring device 100 configured as a clock according to a third embodiment of the invention.

[0124] The time measurement device 100 according to the third embodiment differs from the time measurement device 100 according to the first embodiment by the following design of the oscillation system 102 .

[0125] In this case, the electro-optical converter device 1 comprises a first electro-optical converter 11 and a second electro-optical converter 12. The first electro-optical converter 11 is configured to generate a first clock optical signal and the second electro-optical converter 12 is configured to generate a second clock optical signal. The first electro-optical converter 11 can be configured as a semiconductor laser or a light-emitting diode. The same applies for the second electro-optical converter 12. In contrast to the first embodiment, since two electro-optical converters 11, 12 are provided, the electro-optical converter device 1 does not comprise an optical splitter.

[0126] In particular, the first electro-optical converter 11 is configured to provide a first clock optical signal in the first signal path 3, and the second electro-optical converter 12 is configured to provide a second clock optical signal in the second signal path 4. The first signal path 3 includes a first waveguide 61. The second signal path 4 comprises a second waveguide 62 connecting the second electro-optical converter 12 to the second opto-electrical converter 22. The second waveguide 62 is not mandatory, since this design does not involve temperature compensation, but only the elimination of the processing time of the electronic components. The second signal path 4 can also directly connect the second electro-optical converter 12 to the second opto-electrical converter 22.

[0127] In this embodiment of the time measuring device 100 , both the first electro-optical converter 11 and the second electro-optical converter 12 are controlled by a control signal which may be generated by the control device 5 .

[0128] As already explained, the provision of two electro-optical converters allows the elimination of an optical splitter, which simplifies the design of the oscillator system 102 and thus reduces the expenditure in manufacturing the entire time measurement device 100. Furthermore, the first and second optical clock signals can be easily generated independently of each other.

[0129] FIG. 7 relates to a time measuring device 100 configured as a clock according to a fourth embodiment of the invention.

[0130] The time measurement device 100 according to the fourth embodiment differs from the time measurement device 100 according to the third embodiment by the following design of the oscillation system 102 .

[0131] The first signal path 3 comprises a first waveguide 61 and the second signal path 4 comprises a second waveguide 62. The first waveguide 61 and the second waveguide 62 are configured such that, on the one hand, at a given temperature the transit time of the first clock optical signal in the first waveguide 61 and the transit time of the second clock optical signal in the second waveguide 62 differ from each other, and, on the other hand, the first waveguide 61 and the second waveguide 62 are configured such that the change in the transit time of the first clock optical signal in the first waveguide 61 for a given temperature deviation from the given temperature is the same as the change in the transit time of the second clock optical signal in the second waveguide 62 for the same given temperature deviation.

[0132] For this purpose, the material and / or length and / or cross-sectional design through which light can pass of the first waveguide 61 and / or the second waveguide 62 can be appropriately selected. In this case, the second waveguide 62 is shorter than the first waveguide 61. In this case, the first waveguide 61 is preferably at least three times, preferably at least ten times, more preferably at least 30 times longer than the length of the waveguide of the second waveguide 62.

[0133] In particular, the first waveguide 61 can be configured as a hollow core fiber and the second waveguide 62 can be configured as a solid core fiber, in particular a single mode fiber or a multimode fiber. In this case, the ratio of the expansion coefficient of the first waveguide 61 to the expansion coefficient of the second waveguide 62 can be between 1:30 and 1:4, in particular 1:16.

[0134] The time measurement device 100 according to the fourth embodiment has the advantage that it is possible to compensate for temperature changes of the first waveguide 61, which lead to changes in the original length and in the refractive index of the first waveguide 61. In particular, a temperature sensor can be omitted for this reason, so that measurement inaccuracies can be eliminated.

[0135] FIG. 8 relates to a time measuring device 100 configured as a clock according to a fifth embodiment of the invention.

[0136] The time measuring device 100 according to the fifth embodiment differs essentially from that according to the third or fourth embodiment, in particular by the design of the region of the oscillator system 102 comprising the first signal path 3 .

[0137] As can be seen from Fig. 8, the electro-optical converter device 1 comprises, in addition to the first electro-optical converter 11, a lens 14 behind the first electro-optical converter 11 in the direction from the first electro-optical converter 11 to the first waveguide 61. The lens 14 is configured in particular as a convex lens and serves to refract the light emitted in different directions from the first electro-optical converter 11 in such a way that the light beam is collimated after the lens 14. In other words, the lens 14 is configured to collimate the divergent light of the first electro-optical converter 11. In Fig. 8, the lens 14 is shown as a single lens element. However, it is also possible to configure the lens 14 as an optical system with at least two lens elements.

[0138] At a first end of the first waveguide 61, referred to in the context of the present invention as feed end 611, the light splitter 6 is arranged. In particular, the light splitter 6 is arranged between the first waveguide 61 and the lens 14. In this case, the light splitter 6 is configured as a fiber splitter.

[0139] A reflector 7 is disposed at a second end of the first waveguide 61, which in the context of the present invention is referred to as the reflecting end 612. Light that is fed into the first waveguide 61 at the feeding end 611 and emerges from the first waveguide 61 at the reflecting end 612 can be reflected back into the first waveguide 61 by the reflector 7.

[0140] For this purpose, in particular a concave mirror can be used as reflector 7. In this case, the concave mirror is configured to recollimate the divergent light emerging from the first waveguide 61. In particular, the concave mirror can be a spherical concave mirror. However, it is also possible for the reflector 7 to be any other type of mirror, in particular suitable for reflecting the light beam emerging from the reflecting end 612.

[0141] In this embodiment, the first signal path 3 comprises a first waveguide 61 , an optical splitter 6 , a reflector 7 and a first optical-to-electrical converter 21 .

[0142] In the direction from the first electro-optical converter 11 to the first waveguide 61, particularly the supply end 611 of the first waveguide 61, the optical splitter 6 is configured to pass the first optical signal, and in the direction from the first waveguide 61, particularly the reflecting end 612 of the first waveguide 61, to the first electro-optical converter 11, the optical splitter 6 is configured to output the reflected first optical signal 6 into the first optical-electrical converter 21.

[0143] During operation of the time measurement device 100, the first electro-optical converter 11 feeds a first optical clock signal into the first waveguide 61 via the lens 14 and the optical splitter 6. The first optical signal is reflected by the reflector 7 at the reflecting end 612 into the first waveguide 61 and output by the optical splitter 6 into the first optical-electrical converter 21. That is to say, the optical splitter 6 itself acts on the reflected first optical clock signal, in other words when light passes through the first waveguide 61 in the direction from the reflector 7 to the optical splitter 6.

[0144] The first optical-to-electrical converter 21 converts the first optical signal into a first electrical signal which, as already mentioned above, is transmitted to a phase comparator 50 of the control device 5, in particular to a first input 501 of the phase comparator 50.

[0145] The time measurement device 100 according to the fifth embodiment offers the advantage that in this case the optical path, i.e. the path travelled by the first clock optical signal in the first waveguide 61, is twice the length of the first waveguide 61. Thus, the length of the first waveguide 61 remains the same, while the optical path of the first optical signal can be doubled, which allows to increase the accuracy of the clock of the time measurement device 100. Alternatively, the optical path of the first optical signal remains the same, while the length of the first waveguide 61 can be halved, which allows to save space in the time measurement device 100 and halve the investment, i.e. expenditure, on the first waveguide 61.

[0146] FIG. 9 relates to a time measuring device 100 configured as a clock according to a sixth embodiment of the invention.

[0147] The time measuring device 100 according to the sixth embodiment differs from the one according to the fifth embodiment essentially by the design of the first electro-optical converter 11 .

[0148] In this case, the first electro-optical converter 11 is configured as a pigtailed semiconductor laser or a pigtailed light emitting diode. As a result, in the case of the time measurement device 100 according to the sixth embodiment, the lens 14 provided in the time measurement device 100 according to the fifth embodiment can be omitted.

[0149] FIG. 10 relates to a time measuring device 100 configured as a clock according to a seventh embodiment of the invention.

[0150] The time measuring device 100 according to the seventh embodiment differs from that according to the fifth embodiment essentially by the design of the region of the oscillator system 102 comprising the first signal path 3 .

[0151] In the time measurement device 100 according to the seventh embodiment, a supply lens 8 is attached directly to the supply end 611 of the first waveguide 61. The supply lens 8 is configured to collimate the light entering the first waveguide 61.

[0152] The optical splitter 6 is arranged between the supply lens 8 and the lens 14. In particular, the optical splitter 6 is configured as a partially transparent mirror and serves to output the reflected first clock optical signal into the first electro-optical converter 21. That is, in the direction from the first waveguide 61, in particular from the supply end 611 of the first waveguide 61, to the first electro-optical converter 11, the optical splitter 6 is configured to output the reflected first clock optical signal into the first electro-optical converter 21. The output of the first clock optical signal reflected by the reflector 7 is performed by reflecting said optical signal by the partially transparent mirror to the first electro-optical converter 21. In the direction from the first electro-optical converter 11 to the first waveguide 61, in particular from the supply end 611 of the first waveguide 61, the optical splitter 6 passes the first optical signal generated by the first electro-optical converter 11.

[0153] During operation of the time measurement device 100 , a first optical signal generated by the first electro-optical converter 11 is fed into the first waveguide 61 via the lens 14 , the optical splitter 6 and the feed lens 8 .

[0154] At the reflecting end 612 of the first waveguide 61, the first optical signal is reflected by the reflector 7 back into the first waveguide 61 and fed into the first opto-electrical converter 21 via the feed lens 8 and the optical splitter 6. The first opto-electrical converter 21 converts the first optical signal into an electrical signal which is then directed to a first input 501 of the phase comparator 50 of the control device 5.

[0155] FIG. 11 relates to a time measuring device 100 configured as a clock according to an eighth embodiment of the invention.

[0156] The time measurement device 100 according to the eighth embodiment essentially differs from that according to the seventh embodiment in that in this case the opto-electrical converter device 2 comprises a single electro-optical converter 10 and the time measurement device 100 comprises a single waveguide 61 and an optical splitter 13 for splitting the optical clock signal generated by the electro-optical converter 10 into a first optical clock signal and a second optical clock signal. Furthermore, the optical splitter 13 is configured to output the first optical clock signal reflected by the reflector 7 into the first opto-electrical converter 21. That is to say, the optical splitter 13 has two functions: a splitting function and an output function.

[0157] The light splitter 13 is in particular configured as a partially transparent mirror and is arranged between the supply lens 8 and the lens 14. Furthermore, the second opto-electrical converter 22 is arranged in such a way that the part of the light generated by the single electro-optical converter 10 that is reflected by the partially transparent mirror acting as the light splitter 13 is fed into the second opto-electrical converter 22.

[0158] In this case, in the context of the present invention, the optical splitter 13 can be understood in particular as part of the electro-optical converter device 1. The light that reflects off the partially transparent mirror and reaches the second electro-optical converter 22 corresponds to the second optical clock signal. The second signal path 4 therefore comprises the second electro-optical converter 22. The first signal path 3 comprises the feed lens 8, the single waveguide 61, the reflector 7, the optical splitter 13 and the first electro-optical converter 21. The light that passes through the partially transparent mirror corresponds to the first optical clock signal.

[0159] FIG. 12 relates to a time measuring device 100 configured as a clock according to a ninth embodiment of the invention.

[0160] The time measuring device 100 comprises a single electro-optical converter 10, an optical splitter 13 forming an electro-optical converter device 1, an optical-electrical converter device 2 comprising a single electro-optical converter 20 and a signal splitter 23, a single waveguide 61, a reflector 7 and a supply window 9.

[0161] The reflector 7 is arranged directly above the reflecting end 612 of the waveguide 61 and is advantageously configured as a plane mirror. For this purpose, an end cap can advantageously be arranged directly on the reflecting end 612 of the waveguide 61, the inner surface of this end cap being mirrored, i.e. the surface of the end cap facing the reflecting end 612 of the waveguide 61. This ensures that little or no light is lost after reflection.

[0162] The supply window 9 is arranged directly at the supply end 611 of the waveguide 61. An end cap configured to admit light can be used as the supply window 9. In this case, the light splitter 13 can be configured as a partially transparent mirror, in particular a partially transparent concave mirror, and arranged after the electro-optical converter 10 in the direction from the electro-optical converter 10 to the waveguide 61. Thus, a first part of the light emitted from the electro-optical converter 10 is reflected and collimated by the partially transparent concave mirror and is fed into the waveguide 61 via the supply window 9. The partially transparent concave mirror can also be referred to as a semi-transparent collector mirror. This part of the light corresponds to the first clock optical signal. A second part of the light emitted from the electro-optical converter 10 passes through the semi-transparent mirror and is fed into the opto-electrical converter 20. The second part of the light corresponds to the second clock optical signal. As can be seen from FIG. 12, the concave surface of the partially transparent concave mirror faces the electro-optical converter 10.

[0163] The first and second optical clock signals are acquired by the photoelectric converter 20 at different times, since the two optical signals travel paths of different lengths and are therefore offset in time. The photoelectric converter device 20 generates a first electrical signal based on the first optical clock signal and generates a second electrical signal based on the second optical clock signal. The first and second electrical signals are also offset in time. During operation of the time measurement device 100, the first and second optical clock signals form a superimposed signal. Thus, in other words, the photoelectric converter 20 is configured to generate a superimposed signal formed from the first and second optical clock signals.

[0164] However, in order to be able to distinguish the two electrical signals from one another due to the fact that both the first and second electrical signals are generated by the same photoelectric converter 20, the above mentioned signal splitter 23 is provided. In particular, the signal splitter 23 is configured to split or separate the first and second electrical signals from one another, so that said signals can be directed to the control device 5, in particular to the first input 501 and the second input 502 of the phase comparator 50, respectively. In other words, the signal splitter 23 is configured to generate the first and second electrical signals from the superimposed signal.

[0165] In this case, the first signal path 3 comprises a waveguide 61, a reflector 7, an optical splitter 13 of the electro-optical converter device 1, a single optical-electrical converter 20 and a first signal splitter signal path 231, and the second signal path 4 comprises a single optical-electrical converter 20 and a second signal splitter signal path 232.

[0166] The time measuring device 100 according to the ninth embodiment has the advantage in particular that only a single waveguide, a single electro-optical converter and a single opto-electrical converter are required.

[0167] FIG. 13 relates to a time measuring device 100 configured as a clock according to a tenth embodiment of the invention.

[0168] The time measurement device 100 according to the tenth embodiment differs from that according to the ninth embodiment in that in this case the opto-electrical converter device 2 comprises a first opto-electrical converter 21 for generating a first electrical signal based on a first optical clock signal and a second opto-electrical converter 22 for generating a second electrical signal based on a second optical clock signal.

[0169] It will be understood that the optical splitter 13, configured as a partially transparent mirror, in particular a partially transparent concave mirror, is arranged with respect to the single waveguide 61 in such a way that the part of the optical signal generated by the single electro-optical converter 10, which is reflected by the partially transparent mirror and corresponds to the first clock optical signal, is fed into the waveguide 61. As can be seen from FIG. 12, the concave surface of the partially transparent concave mirror faces the electro-optical converter 10. Furthermore, the partially transparent mirror, the first electro-optical converter 21 and the second electro-optical converter 22 are arranged with respect to each other in such a way that the first clock optical signal reflected by the reflector 7 reaches the first electro-optical converter 21 and the part of the optical signal generated by the single electro-optical converter 10, which passes through the partially transparent mirror and corresponds to the second clock optical signal, reaches the second electro-optical converter 22.

[0170] In order to prevent a part of the first optical clock signal from reaching the second opto-electrical converter 22 and a part of the second optical clock signal from reaching the first opto-electrical converter 21, a separator 24 is advantageously arranged between the first opto-electrical converter 21 and the second opto-electrical converter 22. The separator 24 may in particular be part of the opto-electrical converter arrangement 2. Advantageously, the separator 24 may be configured as a bulkhead.

[0171] In this case, the first signal path 3 comprises a waveguide 61, a reflector 7, an optical splitter 13 of the electro-optical converter device 1 and a first optical-to-electrical converter 21, and the second signal path 4 comprises a second optical-to-electrical converter 22.

[0172] It should be noted that in the described embodiment, as mentioned above, a concave or a plane mirror can be used as reflector 7. In particular, if reflector 7 is configured as a plane mirror, it is particularly advantageous to arrange it directly at the reflective end 612 of the first waveguide 61.

[0173] Although the time measuring device 100 according to the described embodiment is configured as a clock, the invention is also used in other fields of application. For example, the above-mentioned time measuring device 100 can be used in a navigation device without the drive 104, the clockwork 105 and the mechanical clock display 106. Instead, this kind of time measuring device 100, also referred to in the context of the invention as a navigation device time measuring device, can preferably comprise an application-oriented unit. In particular, the application-oriented unit can be a positioning unit configured to determine the position of the navigation device based on the useful signal generated by the useful signal generating device 103. The application-oriented unit can be implemented as software and / or hardware.

[0174] In addition to the above description of the invention, for complementary disclosure thereof, explicit reference is made to exemplary representations of the invention in FIGS. [Explanation of symbols]

[0175] 1. Electro-optical converter device 2. Photoelectric converter device 3. First Signal Path 4 Second Signal Path 5. Control device 6 light splitter 7 Reflector 8 Lens supply 9. Supply Window 10. Electro-optical converter 11 First electro-optical converter 12 Second electro-optical converter 13 Light splitter 14 Lenses 20 Photoelectric converter 21 First photoelectric converter 22 Second photoelectric converter 23 Signal splitter 24 Separator 50 phase comparator 51 Loop Filter 52 Drivable Oscillators 53 First D Flip-Flop 54 Second D Flip-Flop 55 AND Gate 56 Subtractor 61 First Waveguide 62 Second Waveguide 100 Time measuring device 101 Timing Generator Assembly 102 Oscillation System 103 Useful signal generation device 104 Drive unit 105 Clockwork 106 Clock display device 110 Watch Case 120 dial 130 needles 140 Connection 150 Timepiece Glass 160 Wristbands 170 wheels 201 Arrow 202 Arrow 203 Arrow 204 Arrow 205 Arrow 206 Arrow 207 Arrow 208 Arrow 209 Arrow 210 Arrow 231 first signal divider signal path 232 Second signal divider signal path 501 First Input 502 Second Input 531 D Input 532 Clock Input 533 Reset Input 534 Q output 541 D Input 542 Clock Input 544 Q output 551 First Input 552 Second Input 611 Supply end 612 Reflection end

Claims

1. A timepiece (100), in particular a wristwatch, comprising: an electro-optical transducer device (1) having at least one electro-optical transducer (10; 11, 12); A photoelectric converter device (2); a first signal path (3) leading through a first waveguide (61) into the photoelectric converter device (2); a second signal path (4) leading directly or via a second waveguide (62) into the photoelectric converter device (2); A control device (5); A useful signal generating device (103), the electro-optical converter device (1) is configured to provide a first optical clock signal into the first waveguide (61) and a second optical clock signal into the second signal path (4); the photoelectric converter device (2) is configured to generate a first electrical signal based on the first clock optical signal and to generate a second electrical signal based on the second clock optical signal; the first signal path (3) and the second signal path (4) are configured such that a transit time of the first clock optical signal in the first signal path (3) and a transit time of the second clock optical signal in the second signal path (4) are different from each other; the control device (5) is configured to generate a control signal based on a phase difference between the first electrical signal and the second electrical signal, and to drive the electro-optical converter device (1) with the control signal to generate the two optical signals; the useful signal generator (103) is configured to generate a useful signal for clocking a time based on the frequency of the control signal; said clock comprising a clock display (106) for displaying a time based on said useful signal; clock.

2. The clock (100) according to claim 1, wherein the control device (5) comprises a phase comparator (50), a loop filter (51) for integrating the output signal of the phase comparator (50), and an oscillator (52) that can be driven by the output signal of the loop filter.

3. 3. The timepiece (100) of claim 2, wherein the drivable oscillator (52) is a voltage controlled oscillator or comprises a tunable piezoelectric oscillating crystal with a trimmer capacitor.

4. The watch (100) according to any one of claims 1 to 3, wherein the control device (5) is implemented as hardware and / or software.

5. The clock (100) according to any one of claims 1 to 4, wherein the electro-optical converter device (1) comprises a single electro-optical converter (10) configured to generate a clock optical signal and an optical splitter (13) configured to split the clock optical signal into the first clock optical signal and the second clock optical signal.

6. A timepiece (100) according to any one of claims 1 to 4, wherein the electro-optical converter is a first electro-optical converter (11) and the electro-optical converter device (1) comprises a second electro-optical converter (12), the first electro-optical converter (11) configured to generate the first clock optical signal and the second electro-optical converter (12) configured to generate the second clock optical signal.

7. A clock (100) according to any one of claims 1 to 6, wherein the optoelectronic converter device (2) comprises a single optoelectronic converter (20) for generating a superimposed signal formed from the first optical clock signal and the second optical clock signal, and a signal divider (23) configured to generate the first electrical signal and the second electrical signal from the superimposed signal.

8. the photoelectric converter device (2) comprises a first photoelectric converter (21) and a second photoelectric converter (22), the first signal path (3) comprises the first photoelectric converter (21) and the second signal path (4) comprises the second photoelectric converter (22); the first optical-to-electrical converter (21) is configured to generate the first electrical signal based on the first clock optical signal, and the second optical-to-electrical converter (22) is configured to generate the second electrical signal based on the second clock optical signal; A watch (100) according to any one of the preceding claims.

9. 9. The timepiece (100) according to claim 8, wherein the first photoelectric converter (21) is constructed identically to the second photoelectric converter (22).

10. A watch (100) according to any one of the preceding claims, wherein said second waveguide (62) is shorter than said first waveguide (1).

11. The first waveguide (61) and the second waveguide (62) At a given temperature, the transit time of the first clock optical signal in the first waveguide (61) and the transit time of the second clock optical signal in the second waveguide (62) are different from each other, and configured such that the change in transit time of the first clock optical signal in the first waveguide (61) for a given temperature deviation from a given temperature is the same as the change in transit time of the second clock optical signal in the second waveguide (62) for the same given temperature deviation. A watch (100) according to claim 10.

12. 12. The watch (100) according to claim 11, wherein the first waveguide (61) and the second waveguide (62) differ in the material through which light can pass and / or in the length and / or in the cross-sectional design.

13. A clock (100) according to any one of claims 7 to 12, wherein a reflector (7) is arranged at a reflection end (612) of the first waveguide (61) by means of which the first optical clock signal can be reflected back into the first waveguide (61), and the first signal path (3) is configured such that the reflected first optical clock signal can be output into the opto-electrical converter (21; 20) of the first signal path (3) at a supply end (611) of the first waveguide (61).

14. 14. The clock (100) of claim 13, wherein the first signal path (3) comprises an optical splitter (6; 13) at the supply end (611) of the first waveguide (61), the splitter being configured to output the reflected first clock optical signal into the first optical-to-electrical converter (21).

15. 15. The watch (100) according to claim 14, wherein the light splitter (6; 13) comprises a partially transparent mirror or a fibre splitter.

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