The optical measuring method and, optionally, downstream (image) evaluation software enable highly precise, direct monitoring of movement sequences. During the oscillatory movement along the monitored turn section, the adjacent turns of the spiral spring have an image pattern that is characteristic due to the varying spacing, which serves as a benchmark or reference for the (image) evaluation software. Measuring methods suitable for the optical measuring method and adequately described in the prior art include, for example, laser Doppler vibrometry, laser interferometric vibrometry, white light interferometry, also with a confocal microscope, 2D/3D laser scanning, high-resolution digital microscopy with video function, and/or combined laser light—and white light microscopy for 2D/3D scanning. White light interferometry is a purely optical measuring method that records up to a million images per second. A downstream software or stored programming can determine the deflection or the maximum deflection or angular deviation of the adjacent turns from one another based on the irregularities that result from the variance of the spacing. In laser interferometry, for example, the geometry or the spacing between the adjacent turns is scanned or sampled using a laser at 1 million points per second.

The measuring methods mentioned above can be utilized alone or in combination. Particularly in combination, a highly precise, qualitative statement can be made about the oscillation behavior of the spiral spring and starting points for targeted interventions can be identified.

Because of the measurement value recording and evaluation within seconds, the method according to the invention can be utilized particularly in automated assembly lines in line assembly in movement production. Testing and comcomitant regulation of the spiral spring can be carried out fully automatically. The method is also very suitable for pre-regulating entire oscillatory systems as a single-user measurement. The measuring system displays the oscillation width, frequency and rate of the clock directly on the spiral or on a defined turn section. Any interferences such as natural frequencies and deflections from the spiral plane during the oscillation are also made visible. These measurements take place within a few seconds.

If necessary, as part of quality control and in particular to determine the rate accuracy of a mechanical movement, the oscillation frequency can be determined based on the oscillation period of the spiral spring using an optional method variant. A one-time deflection of two adjacent turns relative to each other by the angular deviation corresponds to a half-oscillation of the spiral spring. By measuring the time required for this, the number of half-oscillations or complete oscillations (i.e. two half-oscillations) per unit of time and consequently the oscillation frequency can be determined.

Finally, according to an advantageous variant of the method according to the invention, the rate accuracy or a rate deviation or a rate error of a mechanical movement can be based on the determined oscillation width and/or frequency. For this purpose, a target value/actual value comparison is carried out, wherein the determined oscillation width and/or frequency corresponds to the actual value and this actual value is compared with a corresponding, pre-specified target value. Preferably, the target value data for carrying out the optical measuring method in an automated manner can be stored in advance on an electronic data carrier of a control module suitable for carrying out the measuring method.

Preferably, a geometry of the spiral blade of the spiral spring that is optimized for the measuring method according to the invention is already taken into account during its production, i.e. the spiral spring can be produced with at least one turn section, which is suitable for optically capturing the relative deflection of adjacent turns due to the geometry of the mutually facing side surfaces. For this purpose, the geometry of the side surfaces is formed such that the spacing between the adjacent turns varies along the turn section. Corresponding data regarding the specific geometry of the spiral blade, at least in one turn section, can be stored on an electronic data carrier for an automated manufacturing and measuring method and can be made available both to specify corresponding parameters in the optical measuring method, such as measuring height or spacing definition, as well as to specify the parameters for the production of the spiral spring.

The object of the invention set out at the beginning is therefore also achieved by a spiral spring which is suitable for use in the optical measuring method according to the invention and whose geometry, in particular the configuration of the spiral blade for this purpose, is optimized with regard to its oscillation behavior.

Such a spiral spring according to the invention has several turns which extend along respective circular paths forming a spiral, in particular Archimedean and/or logarithmic course, and can be stimulated to an oscillatory movement, in particular for clocking a mechanical movement, with adjacent turns being deflected relative to each other along their respective circular paths by an angular displacement. The spiral spring according to the invention is characterized in that the spacing between the adjacent turns varies at least along a measuring section corresponding to the angular displacement β, the variance of the spacing (x) between the adjacent turns (110) being brought about by the configuration of the mutually facing side surfaces (131) of the adjacent turns (110) of the spiral spring (100), and is at least 0.02% and at most 1.5% along the measuring section.

Unlike the spiral springs known from the prior art, in which the spacing between adjacent turns along the longitudinal extent, i.e., following the course of the spiral, is constant, the spiral spring according to the invention has a varying or variable spacing.

In order to facilitate the capture of the oscillatory movement and the relative deflection that takes place between adjacent turns during the oscillation, using optical measuring equipment or measuring methods, the variance of the spacing between the adjacent turns along the measuring section is preferably at least 0.025%, 0.04%, 0.05% or 0.1%, more preferably at least 0.25% or 0.3%. The higher the variance, the more precisely the relative deflection can be captured using optical equipment and the more reliable are the determined values for oscillation width and/or frequency. In order to ensure that the oscillation behavior of the spiral spring in the movement continues to be uniform and, in particular, to prevent the adjacent turns from touching each other during the oscillatory movement, the variance is at most 1.5% and preferably at most 1.0%. Each of the value ranges mentioned for the variance of the spacing represents a viable compromise between, on the one hand, suitability as a reference or benchmark for optical measuring equipment for dynamically capturing the angular displacement and, on the other hand, a spiral spring with optimized oscillation behavior for use in mechanical movements.

The spacing between the adjacent turns can vary not only along the course of the turns or the measuring section, but, according to an advantageous design variant, also along the height of the mutually facing side surfaces of the spiral spring, whereby additional benchmarks or reference points are provided for the optical measuring method. Along the height, the variance of the spacing between the adjacent turns is at least 0.01% and at most 2.0%. Preferred values for the variance of the spacing are at least 0.015%, 0.02%, 0.03% or 0.05%, more preferably at least 0.125% or 0.15%, and at most 1.5% or 1.0%. Both along the course of the turn and along the height, the specific variance values are influenced by the configuration of the mutually facing side surfaces of the spiral spring bringing about the variance.

Typically, the spacing between turns of a spiral spring for mechanical movements is constant along the entire course of the spiral and is in most cases 80.0 μm to 200.0 μm. A spacing of 80.0 μm between the turns, for example, results in a deviation of +/−0.016 μm around the mean value when a variance is at least 0.02%. This in turn results in a range of 80.016 μm (=80.0 μm+0.016 μm) to 79.084 μm (=80.0 μm-0.016 μm), within which the spacing along the measuring section or the course of the turn and preferably also along the height should vary at least.

To the contrary, a spacing of 200.0 μm between the turns, for example, results in a deviation of +/−3.0 μm around the mean value when a variance of at most 1.5%. This in turn results in a range of 203.0 μm (=200.0 μm+3.0 μm) to 197.0 μm (=200.0 μm-3.0 μm), within which the spacing along the measuring section or the course of the turn and preferably also along the height should vary at most.

Alternatively or optionally, the spacing along the measuring section can (also) vary continuously or steadily.

The varying spacing is brought about by the geometry or the configuration of the mutually facing side surfaces of the adjacent turns of the spiral spring. According to a preferred design of the invention, the geometry is impacted by the configuration of the surface finish of one or both of the mutually facing side surfaces, which are configured with waviness bringing about the variance of the spacing.

The waviness, i.e. a 2nd order shape deviation of the mutually facing side surfaces, can be better utilized for the dynamic capture with optical measuring equipment than the roughness, i.e. a 3rd or 4th order shape deviation, due to the changes in the wave depth that occur at larger intervals. Due to the much smaller intervals within which the changes in the roughness depth in the roughness profile occur, these changes tend to blur in the imaging dynamic measuring method, during which the turns of the spiral blade move relative to one another at a frequency of 1 to 5 oscillations per second. The changes in wave depth W_tthat occur at larger intervals are significantly easier to dynamically capture using optical equipment, which means that the oscillation width and/or frequency can be evaluated more reliably. Corresponding to the larger intervals, the measuring section along which the waviness is optically captured, must be based on a minimum dimension. A measuring section that is at least 50.0 μm long, or better yet at least 100.0 μm, can be sufficient. Preferably, the waviness is captured along a measuring section corresponding to the angular deviation, with a waviness profile of the opposite side surfaces of the spiral blade along a turn section corresponding to the angular deviation proving to be advantageous.

Typically, it is advantageous to design both of the mutually facing side surfaces with waviness, because in this case the maximum wave depth W_tcan be chosen so as to be smaller in order to achieve the desired variance in the spacing. However, if only one of the two side surfaces is formed with waviness, then this waviness should be chosen so to be at least twice as high.

In this case, the surface finish of the mutually facing side surfaces can have waviness along the course of the turn and/or along the height, that is, the respective waviness profile extends over a turn section corresponding to the measuring section or partially or entirely over the height of the side surface of the spiral blade.

By configuring the mutually facing side surfaces of the spiral blade with waviness in order to bring about the variance of the spacing, the roughness of the side surface, i.e. the values for the roughness depth, can at the same time be chosen to be low in order to reduce stresses within the spiral blade and consequently minimize the risk of breakage of the spiral blade. A roughness depth value R_zof one or both mutually facing side surfaces of at most 0.5 μm turned out to provide a suitable roughness profile, but the roughness depth value is preferably lower, in particular between 0.5 μm and 0.005 μm.

According to an exemplary variant of the invention, in particular in order to realize the desired values for the variance of the spacing resulting from the surface finish or geometry and at the same time to realize the lowest possible roughness of the side surfaces of the spiral blade, the spiral spring is made of silicon, preferably monocrystalline or polycrystalline silicon by means of an etching process and optionally provided with a silicon oxide or silicon dioxide coating.

The desired waviness profile bringing about the variance of the spacing can then optionally or as needed be configured on the surface or the side surfaces of the core of the spiral spring and/or on the coating covering the side surfaces. The dynamic, optical capture of the surface finish then takes place accordingly on the coating and/or on the core of the spiral spring, for example by means of interferometry, which is also utilized in semiconductor technology to determine layer thickness.

According to an exemplary variant of the invention, the geometry of the mutually facing side surfaces is configured such that the spacing between the turns varies either over the entire height of the spiral blade, or only at a certain height or a certain height range along the measuring section.

Preferably, the height of the spiral blade is constant along the entire course of the spiral and ranges, for example, from 80 μm to 160 μm. The width of the spiral blade, which is usually around 25 to 45 μm, is basically constant along the entire course of the spiral. However, due to the changed geometry of the mutually facing side surfaces, deviations occur which correspond to the variance of the spacing between the adjacent turns.

In a preferred design of the invention, the spacing between the adjacent turns, for example in the area of the lower longitudinal edge, can deviate from the spacing between the adjacent turns in the area of the upper longitudinal edge of the mutually facing side surfaces, the spacings in the area of the upper longitudinal edge and/or in the area of lower longitudinal edge varying along the measuring section. In particular, the spacing in the area of one of the longitudinal edges, preferably the upper longitudinal edge, can be constant along the entire spiral course and can vary in the area of the other longitudinal edge, preferably the lower longitudinal edge, at least along the measuring section. This can then result in a likewise constant width of the spiral blade in the area of the upper longitudinal edge and a width of the spiral blade in the area of the lower longitudinal edge that deviates according to the variance of the spacing at least along the measuring section. The designation “upper” and “lower” longitudinal edge refers to the installation position of the spiral spring or the movement in a chronograph, viewed from the back in the direction of the dial.

According to a design variant of the spiral spring according to the invention, the mutually facing side surfaces are configured to include an opening angle in between, the opening angle varying along the measuring section, bringing about the variance of the spacing.

Normally, the spiral blade of a spiral spring has a rectangular cross section, with the height of the spiral blade parallel to its axis of rotation. The opening angle can be formed by an oblique course of one or both side surfaces over the height, i.e. the course of the side surface(s) is then no longer parallel to the axis of rotation. The average opening angle can in principle be 0°, but preferably ranges from 1.0° to 20.0°, more preferably from 1.0° to 10.0°, or particularly preferably from 1.0° to 7.00. Alternatively, the opening angle is at least 2.0° or at least 3.0° and then ranges, for example, from 2.0° to 10.0°, preferably from 2.00 to 7.0°, or particularly preferably from 3.0° and 5.0°. In order to bring about sufficient variance in the spacing between the adjacent turns, a variance in the opening angle is at least 0.1°, at least along the measuring section.

For an opening angle of, for example, 3°, there is a deviation of +/−0.1° around the mean with a variance of at least 0.1°. This in turn results in a range of 3.1° (=3.0°+0.1°) to 2.9° (=3.0°-0.1°), within which the opening angle along the measuring section or the course of the turn should vary at least.

Particularly advantageous, both for the optical measuring method and in terms of oscillation behavior, is a spiral spring in which the variance of the spacing between adjacent turns is brought about by a combination of the opening angle varying along the measuring section and waviness along the course of the turn and/or along the height of one or both of the mutually facing side surfaces. That is to say that, on the one hand, the opening angle varies along the course of the turn or along the measuring section, and there is a respective partially or entirely varying waviness profile over a turn section corresponding to the measuring section and/or over the height of the side surface of the spiral blade.

A design variant is comparatively easy to produce, in which the opening angle is formed by an oblique course of one or both side surfaces with respect to the height, and varies along the measuring section, i.e. along the course of the turn, and at the same time the waviness varies along the height, i.e. the oblique course of the side surface. The zero line of a waviness profile derived therefrom then corresponds to the height that runs obliquely to the axis of rotation in the cross section of such a spiral blade.

According to other design variants of the spiral spring according to the invention, the mutually facing side surfaces can be formed to follow a concave and/or convex course over the height and/or to have a rounded or beveled transition area in the area of the upper and/or lower longitudinal edge, the concave course and/or the rounding or bevelling of the transition area along the measuring section varying.

A concave and/or convex course of the side surface can optionally be formed on one or both side surfaces, with the course extending either over the entire height or only a subsection of the height. A beveled and/or rounded transition area is formed on the upper and/or lower longitudinal edges of one or both side surfaces. In order to bring about sufficient variance in the spacing, a variance in the transition area along the measuring section is preferably at least 10%, 20% or 25%, in particular at least 40%. An edge rounding of 2.0 μm, for example, results in a deviation of +/−0.5 μm around the mean with a variance of at least 25%. This in turn results in a range of 1.5 μm (2.0 μm-0.5 μm) to 2.5 μm (2.0 μm+0.5 μm), within which the edge rounding along the measuring section or the course of the turn varies at least.

According to an alternative design of the invention, the spacing between the adjacent turns is the same over the entire height of the mutually facing side surfaces and varies along the measuring section. For example, a continuously or steadily varying or irregular course of the upper and lower longitudinal edges along the measuring section can continue into the corresponding side surfaces, so that a spacing between the adjacent turns that is constant over the height of the spiral blade and varies along the measuring section is generated. This has the advantage that the spacing can be captured optically at any measuring height, which means that the recording of measured values is clearly secured.

According to a preferred variant of the invention, the geometry of the mutually facing side surfaces of the turns in the area of the upper and/or lower longitudinal edges is formed such that the longitudinal edge(s) has/have an irregular or varying course, at least along the measuring section.

Of course, a combination of one, several or all of the previously described exemplary embodiments is also conceivable in order to bring about the minimum variance in the spacing required for dynamic, optical capture.

Finally, for the oscillation behavior and the breakage resistance of the spiral spring, it can be advantageous if, according to an exemplary design, it has a spiral blade whose shape, in particular its side surfaces, follows a curvature that steadily decreases from the inner end of the turn to the outer end of the turn and/or which is solid.

Further details, features, feature sub(combinations), advantages and effects based on the invention will be apparent from the following description of a preferred exemplary embodiments of the invention and from the drawings. In the drawings

FIG. 1 shows a perspective representation of an oscillatory system of a mechanical movement known from the prior art, with a spiral spring,

FIG. 2 shows a perspective representation of the spiral spring of FIG. 1 in a tension-free central position,

FIG. 3 shows a schematic, radial sectional view of two adjacent turns of the spiral blade of the spiral spring of FIGS. 1 and 2,

FIG. 4 shows a top view of the spiral spring of FIGS. 1 to 3 in a position deflected by half the oscillation width,

FIG. 5 shows an exemplary plot of the course of oscillation of a spiral spring,

FIG. 6 shows a schematic, radial sectional view of several adjacent turns of the spiral blade of the spiral spring of FIGS. 1 to 4, with measuring equipment positioned thereon, according to a method variant according to the invention,

FIG. 7 shows schematic representation of the oscillation-related change in the turn spacing during the oscillatory movement of a spiral spring,

FIG. 8 shows a schematic representation of the oscillation-related change in the turn spacing overlayed with an exemplary variance of the spacing according to the invention caused by the component geometry,

FIG. 9 shows a schematic perspective representation of a turn section with two adjacent turns according to a first embodiment of the invention, with a spacing varying in a transition area,

FIG. 10 shows a schematic perspective representation of a turn section with two adjacent turns according to a second embodiment of the invention, with a concave geometry of the side surfaces,

FIG. 11 shows a schematic perspective representation of a turn section with two adjacent turns according to a third embodiment of the invention, with varying opening angle,

FIG. 12 shows a schematic perspective representation of a turn section with two adjacent turns according to a fourth embodiment of the invention, with a spacing varying along the upper and lower longitudinal edges in each case,

FIG. 13 shows a schematic perspective representation of a turn section with two adjacent turns according to a fifth embodiment of the invention, with a spacing constant over the height of the side surfaces and varying along the turn section,

FIG. 14 shows a perspective representation of a spiral spring according to a sixth embodiment of the invention, in a position deflected by half the oscillation width and with a side surface of the spiral blade in an enlarged representation,

FIG. 15 shows a visual representation of the metrologically captured surface finish of the enlarged side surface of FIG. 14, as well as the associated roughness, waviness and primary profile along the measuring section or the course of a turn of the spiral blade, and in

FIG. 16 shows an optical representation of the metrologically captured surface finish of the enlarged side surface of FIG. 14, as well as the associated roughness, waviness and primary profile along the height of the spiral blade.

The figures are merely exemplary in nature and serve to increase the understanding of the invention. Same elements are provided with the same reference numerals.

FIG. 1 shows a perspective representation of an oscillatory system 200 for mechanical movements known from the prior art. Oscillating system 200, also referred to as a balance wheel, comprises, as essential components, an oscillating body 210, here formed as a flywheel, and a spiral spring 100. Oscillating body 210 serves as an oscillating weight and is rotatably mounted about an axis of rotation 220. Spiral spring 100 is attached with its inner turn end 140 to an inner spring fastener 230 and with its outer turn end 150 to an outer spring retaining element 240. In between, spiral blade 130, which is rectangular in cross section, extends in a spiral course with several turns 110, which form the active oscillation section of spiral spring 100. For clocking the movement, the force coming from the barrel is transferred to oscillation system 200, so that spiral spring 100 oscillates as evenly as possible around its tension-free central position. When leaving the central position, oscillating body 210 brings about pretensioning of spiral spring 100, whereby a restoring torque is generated, which causes spiral spring 100 to return to its central position. This imparts kinetic energy to oscillating body 210, causing spiral spring 100 to oscillate in the other direction beyond its central position. Spiral spring 100 oscillates back and forth once according to its oscillation width. Oscillation widths of flat spiral springs for mechanical movements are usually 200° to 300°.

FIG. 2 shows a perspective representation of spiral spring of FIG. 1 in its tension-free central position. This is shown using the purely illustrative markings on turns 110. The markings are only present in the drawing and do not represent part of actual spiral spring 100. The oscillation width of about 220° within which spiral spring 100 moves around the central position is also shown as an example.

FIG. 3 shows a schematic, radial sectional view of two adjacent turns 110 of spiral blade 130 of spiral spring 100 of FIGS. 1 and 2. It can be clearly seen that spiral blade 130 forming individual turns 110 has a rectangular cross section with a height h and a width b. Height h, width b and spacing x between adjacent turns 110 are constant along the spiral course of spiral blade 130. For example, height h can be a value between 120 μm and 140 μm, width b can be a value between 25 μm and 40 μm, and spacing x can be a value between 80 μm and 200 μm.

FIG. 4 shows a top view of spiral spring 100 of FIGS. 1 to 3 in a position deflected by half the oscillation width. During the oscillatory movement, the direction of which is indicated by an arrow in the drawing, individual turns 110 follow their respective circular paths and move around the center or the axis of rotation 220. Based on the illustrative marking, it can be clearly seen that within a turn section 120, mutually adjacent turns 110 are subject to a relative movement during the oscillatory movement of spiral spring 100, i.e., they are deflected relative to one another by a spacing running along the corresponding circular path. In the position shown here, spiral spring 100 is at its reversal point UP after a half-oscillation, so that adjacent turns 110 are deflected relative to one another by a maximum amount, which corresponds to the angular displacement β, which is also shown. Typical values for the angular displacement β range from 5° to 30°.

FIG. 5 shows the course of a full oscillation of spiral spring 100 based on its deflection about its tension-free central position 0. Also shown are the reversal points UP, where the direction of the oscillation is reversed. Spiral spring 100 is first deflected from tension-free central position 0 in a first direction until the maximum deflection at the reversal point UP is reached and then returns in the opposite, second direction to tension-free central position 0 (half-oscillation). One oscillation is complete after tension-free central position 0 has been passed in the second direction, and spiral spring 100 returns to tension-free central position 0 again following the first direction following another reversal of direction at the reversal point UP. Individual turns 110 follow a corresponding movement along their respective circular paths, resulting in relative movement causing the angular displacement β (see FIG. 4) between adjacent turns 110 in each case.

According to the invention, the oscillation width of the spiral spring 100 should now be determined using an optical measuring method based on this angular displacement β. For this purpose, as shown in FIG. 6, optical measuring equipment 160, for example. light transmitters and/or light receivers, is aligned with a respective turn section 120, preferably vertically from above or below, i.e. parallel to axis of rotation 220 or to height h of the spiral blade, or obliquely, i.e. at an angle greater than or less than 90°, here for example about 45° with axis of rotation 220 or height h. The arrangement of optical measuring equipment 160 shown here is merely an example. A single optical measuring equipment 160 is sufficient to carry out the measuring method according to the invention.

Optical measuring equipment 160 is used to monitor the respective turn section 120, with the deflection of adjacent turns 110 relative to one another being captured optically. spacing x between adjacent turns 110 within at least one turn section 120 serves as a benchmark or reference for optical measuring equipment 160. For this purpose, spacing x in the longitudinal direction of turns 110, i.e. following the spiral course, must not be constant, otherwise the relative movement would not be optically detectable. A “visualization” of the relative movement or deflection of adjacent turns