Galvanometer drive device with gapless support

Abstract

The present invention relates to a galvanometer driving device, the galvanometer driving device comprising: a rotor (110) rotatable about a rotation axis (R), the rotor having a magnet; and a stator unit (130) surrounding the rotor (110), the stator unit having a coil, the rotor being supported by means of two bearings such that the rotor can perform a rotational movement about the rotation axis (R) relative to the stator unit (130), at least one of the bearings being a floating bearing (150, 155), characterized by radial movement limiting means (170, 280, 600, 750, 800), the radial movement limiting means being adapted to limit the radial movement of the floating bearing (150, 155) with respect to the stator unit (130).

Description

Field of the Invention

[0001] The present invention relates to a galvanometer drive device, in particular a galvanometer drive device for precisely aligning laser radiation to a processing position, such as in laser applications. Here, the galvanometer used typically has a mirror that deflects within a limited angular range for aligning the laser radiation to the processing position, and the angular range is less than + / - 90°, typically less than + / - 30°. Background Art

[0002] First, to illustrate the basic problem of the present invention, reference should be made to Figure 1 a detailed description of the prior art known to the applicant.

[0003] Figure 1 A known galvanometer drive device for the applicant is shown. Inside a stator unit 130 having a coil 125, a rotor 110 having a permanent magnet is provided. Here, the rotor is held by means of two bearings 140 and 150 such that the rotor can rotate about a rotation axis R relative to the stator unit 130, and the rotation axis extends horizontally and centrally through the rotor in Figure 1 the figure. In the present application, the direction of the rotation axis R is referred to as the axial direction, and the direction perpendicular to this axis is referred to as the radial direction.

[0004] By supplying a control current via an electrical connection element 300, a change in the magnetic field in the coil 125 of the stator unit 130 is caused, and then the rotor 110 including the magnet performs a rotational movement relative to the magnetic flux guide 120 of the coil 125 or relative to the stator unit 130. In order that the linear expansion of the rotor due to thermal effects does not cause mechanical stress, the bearing 150 is configured as a floating bearing different from the fixed bearing 140, and the mechanical stress may cause damage to the rotor or the bearings 140 and 150 or affect the instrument accuracy. This is achieved such that the outer ring 150a of the bearing 150 and the bearing seat in the stator unit 130 form a clearance fit. The wave spring 200 is assembled under preload such that the bearing 150 can follow the thermal movement within a certain range in the case of thermal movement (size change) of the rotor 110. Here, the wave spring 200 fixes the axial position of the bearing 150 such that the bearing actually only changes the axial position during thermally induced movement.

[0005] The use of the floating bearing 150 causes: the limitation of the rotatability can be avoided, or the rotor and the bearing can be prevented from being overloaded due to thermal stress. In particular, the inner ring 150b of the bearing is fixedly connected to the rotor 110, while the outer ring 150a has a certain mobility in the axial direction by providing a gap (clearance fit). Here, the wave spring 200 causes a preload, which makes the movement of the outer ring of the bearing in the axial direction difficult and results in a tension between the outer ring and the inner ring, such that the outer ring and the inner ring cannot move relative to each other radially. However, the inventor may determine that the accuracy achievable with such a galvanometer drive device is not sufficient, for example, in an environment where the galvanometer drive device is subjected to shocks and vibrations. Summary of the Invention

[0006] Therefore, the object of the present invention is to provide a galvanometer drive device that is also suitable for accurately aligning radiation to a machining position.

[0007] This object is solved by a galvanometer drive device according to the present invention. In particular, the device according to the invention in the following-described embodiment can also be improved by the features of another following-described embodiment, even if this is not explicitly stated.

[0008] The galvanometer drive device according to the present invention includes: a rotor rotatable about a rotation axis, the rotor having a magnet; and a stator unit surrounding the rotor, the stator unit having a coil. The rotor is supported by means of two bearings such that the rotor can perform a rotational movement about the rotation axis relative to the stator unit, and at least one of the bearings is a floating bearing, characterized by a radial movement restricting device that is adapted to restrict the radial movement of the floating bearing with respect to the stator unit.

[0009] Here, the radial direction of the galvanometer drive device is substantially, preferably precisely, perpendicular to the direction of the rotation axis. Therefore, the rotation axis extends substantially, preferably precisely, in the axial direction.

[0010] The inventors have recognized that when high precision is required for the galvanometer drive device, the radial movement of the rotor must be made difficult. In the presence of an axially preloaded floating bearing, although disturbing radial movement does not exist in the bearing itself, the outer ring of the bearing must have a certain dimensional deficiency so that it can be axially movably held in the bearing housing. Thereby, the outer ring has a radial clearance in the bearing housing, that is, relative to the element holding the outer ring of the floating bearing. The problem is that although it is theoretically possible to eliminate the radial movability by considering the fixed connection between the floating bearing and the element holding the floating bearing, such a fixed connection would turn the floating bearing into a fixed bearing with known drawbacks (such as tension during thermal expansion). Therefore, the galvanometer drive device according to the invention is provided with its own radial movement limiting means, the purpose of which is not to eliminate the radial clearance in the floating bearing itself, but to limit the radial movement of the floating bearing relative to the element holding the outer ring of the floating bearing. Here, the limitation of the radial movement is understood not only as the difficulty of the radial movement, that is, the reduction of the movability, but also as the prevention of the radial movement.

[0011] The bearing is installed between the rotor and the stator unit. In this regard, an element rigidly connected to the stator unit is also regarded as a part of the stator unit. Such an element rigidly connected to the stator unit can be, for example, a magnetic flux guide, which is understood as a component arranged outside the coil and used to guide the magnetic flux generated by the coil, especially also for establishing a closed magnetic circuit. In addition, the outer housing of the stator unit can also be regarded as an element rigidly connected to the stator unit, even if it cannot or can only exert a very slight effect on the magnetic flux generated by the coil. In short, if it is mentioned that an object is installed on the stator unit or arranged relative to the stator unit, this object can in particular be installed on an element rigidly connected to the stator unit, such as a magnetic flux guide in the stator unit or the outer housing of the stator unit.

[0012] The stator can in particular have a structure of a straight cylinder, especially a cylindrical or prismatic structure, whose axis of symmetry extends in the direction of the rotation axis. Here, the mathematical concept of a cylinder is based. Here, the case where there is a small taper of the cylinder or prism should also be included.

[0013] Preferably, the floating bearing has an outer ring, an inner ring and a plurality of rolling elements between the inner ring and the outer ring, and the inner ring is rigidly fixed to the rotor and the outer ring can move in the direction of the rotation axis, and the radial movement limiting means limits the radial movement of the outer ring with respect to the stator unit.

[0014] The floating bearing can be a rolling bearing, with its inner ring mounted on the rotor and its outer ring mounted on the stator unit. All structural forms known in the prior art are considered for the rolling bearing. Rigid fixation is understood in this application as a fixed connection that does not allow free movement space.

[0015] Further preferably, the ratio of the radial stiffness to the axial stiffness on the floating bearing is greater than 10, preferably greater than 50, and still more preferably greater than 100.

[0016] Although preferably the radial movement should be completely blocked by the radial movement restricting device, this may lead to problems as already mentioned when the axial movability of the floating bearing is also restricted too strongly. Preferably, however, the radial movement restricting device is designed at least such that the mentioned ratio of the radial stiffness to the axial stiffness is obtained, i.e., defined movability in the axial direction due to relatively small forces and (as small as possible) movability in the radial direction even at high forces. The possible upper extreme value is in the range of 1000 here. The concept "stiffness" can, for example, relate to the movement stiffness or spring stiffness provided by the radial movement restricting device. Generally, the radial or axial (movement) stiffness refers to the resistance to displacement or movement in the radial direction or axial direction.

[0017] Further preferably, the radial movement restricting device is a spring element mounted on the floating bearing, by which the floating bearing is axially loaded with pressure, and the spring element is rigidly fixed to the floating bearing with one section and rigidly fixed to the stator unit with another section.

[0018] Preferably, the spring element extends in the radial direction and has rotational symmetry here. Since the spring element axially loads the floating bearing with pressure, the spring element simultaneously fulfills two tasks: on the one hand, causing the floating bearing to move only in the axial direction during thermal movement in fact by the axially applied pressure, and on the other hand, restricting the radial movability, in such a way that the radial movement of the floating bearing relative to the stator unit becomes more difficult in a larger range compared to the axial movement.

[0019] Further preferably, the spring element has a rotationally symmetric, star-shaped arrangement structure of n leaf spring elements, where n is a natural number greater than or equal to 3.

[0020] Example values for n can be n = 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 20, 50, or 100. It may not be possible to achieve values above n = 100 in practice, so n = 100 can be regarded as the upper extreme value.

[0021] Further preferably, the number n of the leaf spring elements is less than or equal to 100, preferably less than or equal to 20, and more preferably less than or equal to 8.

[0022] Further preferably, the spring element is configured as a disc spring or a diaphragm spring.

[0023] The disc spring or the diaphragm spring can be regarded as a special case of a rotationally symmetric, star-shaped arrangement of leaf spring elements, that is, as an embodiment in which the leaf spring elements transition into each other. A hybrid form is also conceivable here, in which only a part of the leaf spring elements transitions into each other, but preferably there is rotational symmetry. In a special design, the disc spring or the diaphragm spring is provided with voids preferably arranged rotationally symmetrically.

[0024] Further preferably, the spring element has a translational stiffness or a spring stiffness in the radial direction, and the translational stiffness or the spring stiffness is greater than the translational stiffness or the spring stiffness in the axial direction by a factor of at least 50, more preferably at least 100, and even more preferably at least 300.

[0025] A high ratio of the translational stiffness or the spring stiffness in the radial direction to the translational stiffness or the spring stiffness in the axial direction can particularly be obtained by a rotationally symmetric, star-shaped arrangement of leaf spring elements. The upper extreme value of the ratio for the spring constant may be around 1000 in practice.

[0026] Further preferably, the translational stiffness or the spring stiffness in the radial direction has a value above 4 kN / mm, preferably above 20 kN / mm and below 1000 kN / mm.

[0027] The spring stiffness can be adjusted mainly by selecting the material thickness (sheet thickness) for constructing the spring element, by the number and position of the reinforcement parts in the material, by the pre-tension in the installed state, or by the structure and / or number of the star-shaped leaf spring elements, for example.

[0028] Further preferably, the radial movement limiting device is a rolling guide device installed between the floating bearing and the stator unit, and the rolling guide device is rigidly connected to both the floating bearing and the stator unit.

[0029] The rolling guide device can be configured as a constant velocity joint guide device or a ball guide device, for example, which can then receive the axial movement of the floating bearing and simultaneously prevent the radial movement of the floating bearing.

[0030] Further preferably, the rolling guide device includes an inner guide device element, an outer guide device element, and a plurality of rolling elements arranged therebetween.

[0031] The internal component of the guiding device can be a hollow guiding shaft, which radially surrounds the floating bearing and is rigidly connected to the floating bearing, especially its outer ring. The external component of the guiding device can be a guiding shaft sleeve, which radially surrounds the internal component of the guiding device together with the rolling elements arranged therebetween and is rigidly connected to the stator unit. The rolling elements (balls) can be constructed especially not only in a single row but also in multiple rows, and the rolling elements are held at equal distances by a cage. Regarding the materials suitable for the rolling guiding device, the materials known in the prior art can be used, namely especially steel or ceramics for the rolling elements and brass, plastic or steel for the cage.

[0032] Further preferably, the internal component of the guiding device is constructed integrally with the floating bearing and / or the external component of the guiding device is constructed integrally with the stator unit.

[0033] The one-piece implementation is used on the one hand to extremely effectively prevent movement between the internal component of the guiding device and the floating bearing or between the external component of the guiding device and the stator unit. On the other hand, the construction is simplified by reducing the number of components.

[0034] Further preferably, the rolling guiding device is preloaded.

[0035] By preloading, the radial clearance inside the rolling guiding device is prevented, that is, the relative radial movement of the internal component of the guiding device with respect to the external component of the guiding device. Due to the preloading, the rolling elements roll in a force-locking manner between the guiding shaft and the guiding shaft sleeve.

[0036] Further preferably, the radial movement limiting device loads the floating bearing with a force in the radial direction.

[0037] By means of the force acting on the floating bearing in the radial direction, the radial movement of the floating bearing in this direction is restricted. Even if the force applied to the floating bearing also has a component acting in the axial direction, however, the movement in the radial direction is made difficult by the component acting in the radial direction.

[0038] Further preferably, the radial movement limiting device has a spring element, which is installed between the stator unit and the rotor in such a way that the spring element applies a force to the rotor in the radial direction.

[0039] For the spring element, different forms of design are possible. For example, the spring element can be constructed as a helical spring or a rubber spring, and the concept "rubber" replaces any suitable elastic material. The spring element can especially also have an elastic pressure member, by means of which the position and the spring force can be adjusted.

[0040] Further preferably, the radial movement limiting device has a weight which, due to the action of gravity, exerts a force on the floating bearing in the radial direction.

[0041] The gravity can be generated, for example, by constructing the outer ring of the floating bearing from a material with a high specific weight. Alternatively or additionally, a corresponding weight can be provided outside the floating bearing and connected to it.

[0042] Further preferably, the radial movement limiting device loads the floating bearing with a force in the radial direction by means of electromagnetic interaction.

[0043] The corresponding force can be generated, for example, by means of a switchable electromagnet or a permanent magnet.

[0044] Further preferably, the force acting on the rotor in the radial direction is generated by creating a radially asymmetric magnetic field between the rotor and the stator unit.

[0045] Such a radially asymmetric magnetic field results in a radially asymmetric magnetic flux and thus in a force acting in the radial direction between the floating bearing and the stator unit.

[0046] Further preferably, a radially asymmetric magnetic field is generated by the asymmetry of the rotor and / or the stator unit, in particular by the presence of at least one region in the rotor or in the stator unit with a magnetic susceptibility different from that of the rest of the rotor or the stator unit.

[0047] The asymmetry of the field lines of force can be generated by the radial asymmetry of the stator unit, such as a flux guide or an outer housing, or of the rotor. Regions with different magnetic susceptibilities can in particular be cavities (for example filled with gas). Description of the Drawings

[0048] Other features and advantages of the present invention emerge from the description of the embodiments with the aid of the drawings.

[0049] Figure 1 Shows a galvanometer drive known to the applicant;

[0050] Figure 2 Shows a galvanometer drive according to a first embodiment of the present invention;

[0051] Figure 3 Shows a second embodiment of the galvanometer drive according to the present invention;

[0052] Figure 4 Shows a special design of the spring element of the second embodiment;

[0053] Figure 5Shows the installation of the spring element for the second embodiment;

[0054] Figure 6 Shows a variant of the galvanometer drive device according to the third embodiment of the present invention;

[0055] Figure 7 Shows another variant of the galvanometer drive device according to the third embodiment of the present invention; and

[0056] Figure 8 Shows yet another variant of the galvanometer drive device according to the third embodiment of the present invention. Detailed implementation

[0057] First embodiment

[0058] Figure 2 Shows the galvanometer drive device according to the first embodiment of the present invention. In Figure 2 The shown galvanometer drive device is very similar to Figure 1 The galvanometer drive device of. Therefore, the same elements are usually provided with the same reference numerals. In order to define the radial movement of the floating bearing with respect to the stator unit 130, which radial movement may cause an undesired radial movement of the rotor 110, according to the first embodiment, rolling guide means 170 are provided between the floating bearing ( Figure 2 Reference numeral 155 in) and the housing 130 in order to cause a limitation of the radial movement. In particular, the rolling guide means 170 are inserted between the guide shaft 160 and the stator unit 130. The guide shaft 160 is a hollow cylindrical element which is rigidly connected to the outer ring 155a of the floating bearing 155. In addition, the guide shaft 160 is rigidly connected to the rolling guide means 170. In Figure 2 In, this guide shaft 160 acts as the "inner ring" of the rolling guide means 170. The outer ring (guide shaft sleeve) of the rolling guide means 170 is rigidly connected to the stator unit 130, Figure 2 Shows an example in which the outer ring is integrally formed with the stator unit 130.

[0059] In the described arrangement, the outer ring 155a of the floating bearing 155 can move against the spring force of the wave spring 200. Since the floating bearing 155 is rigidly connected to the guide shaft 160 and there is a rolling guide device 170, the movement of the floating bearing 155 in the axial direction causes the guide shaft 160 and the floating bearing 155 to be movable relative to the stator unit 130 in the axial direction. The movement of the floating bearing in the radial direction is prevented on the one hand by the rigid connection between the floating bearing 155 and the guide shaft 160 on the one hand and between the guide shaft 160 and the stator unit 130 on the other hand. On the other hand, the radial movability within the rolling guide device can be prevented by preloading, for example, in such a way that the rolling elements (balls) have an excess with respect to the distance between the guide shaft and the guide bushing.

[0060] The rigid connection of the floating bearing 155 to the guide shaft 160 or of the guide bushing to the stator unit can be obtained not only by an integral or one-piece construction of the outer ring 155a of the floating bearing and the guide shaft 160 or of the guide bushing and the stator unit. Other possibilities for a gapless connection are press fits, adhesives or other connection types that eliminate movability in the axial and radial directions.

[0061] Second embodiment

[0062] Figure 3 Shows a second embodiment of a galvanometer drive device according to the invention. Elements that are the same as or similar to the Figure 1 elements are usually again provided with the same reference numerals. Here, the floating bearing 150 together with its outer ring 150a can in particular be constructed in the same way as the floating bearing 155, except for the rigid or one-piece connection of the outer ring 155a to the guide shaft 160. Different from the Figure 1 design, in Figure 3In the second embodiment, no wave spring 200 is located on the end side of the floating bearing 150. Instead, the stator unit is provided with a clearance portion 135 for receiving the spring element 280 on the end side. The spring element 280 surrounds the floating bearing 150 in the radial direction and acts radially on the outer ring 150a of the floating bearing 150. Here, the spring element extends substantially in the radial direction, i.e., perpendicular to the rotational axis R. The spring element 280 acts on the stator unit 130 on the outside (in the radial direction). In order to clamp the spring element 280, not only the outer ring 150a of the floating bearing 150 but also the stator unit 130 can be provided with grooves into which the spring element 280 is inserted. The spring element 280 is characterized in that in the installed state, its extension in the radial direction is preferably at least eight times greater than its extension in the axial direction. Here, the extension in the radial direction represents the extension between the floating bearing 150 and the stator unit 130, i.e., more precisely the radius (if the spring element 280 is circular) rather than the diameter. It should be noted that: The spring element does not have to be compulsorily installed in the clearance portion 135 of the stator unit 130, and optionally the clearance portion can also be omitted as long as there is sufficient space to fix the spring element on the outside of the outer ring of the floating bearing.

[0063] Due to the special shaping and dimensions of the spring element 280, the spring element can have a much greater stiffness in the radial direction than in the axial direction. Thereby, the wave spring can be replaced to limit, but not completely prevent, the axial mobility of the floating bearing, so that, for example, thermal expansion of the rotor can occur. Conversely, the greater stiffness in the radial direction suppresses movement in the radial direction. The ratio of the spring constant or spring stiffness in the radial direction and the axial direction relative to each other can be adjusted by the shaping of the spring element and mainly by its outer diameter. The larger the outer diameter, the greater the ratio of the spring constant or spring stiffness in the radial direction and the axial direction relative to each other given the inner diameter. The value to be adjusted for the spring stiffness or spring constant in the radial direction is also related to the dimensions of the spring element in the radial direction and additionally to the mass to be moved. It has been proven that for the usual application range of the galvanometer drive device, a value above 4 kN / mm is sufficient for the spring stiffness or spring constant in the radial direction, and a value above 20 kN / mm is preferably selected. Of course, in practice, there is also an upper extreme value for the possible spring constant or spring stiffness in the radial direction, which should probably first be reached at approximately 1000 kN / mm.

[0064] The spring element can, for example, be constructed from a steel plate with a plate thickness of, for example, 0.5 mm. The spring element can in particular be a disc spring. The latter can additionally be constructed such that when there is radial symmetry in the installed state, the axial position of the annular region of the disc spring changes periodically (e.g., sinusoidally) with the position of the region in the radial direction.

[0065] A larger ratio between the radial spring constant and the axial spring constant can be obtained when using a type of spring star that replaces a full-surface disc spring, as shown in Figure 4 . In Figure 4 , the spring element 280 can be seen, which is constructed from an inner ring 281 that abuts against the floating bearing 150 and an outer ring 282 that abuts against the stator unit 130. The inner ring 281 and the outer ring 282 are interconnected via a rotationally symmetric, star-shaped arrangement of three leaf spring elements 283. The leaf spring elements 283 have an elongated structure similar to the spokes of a steering wheel. Preferably, the ratio of the extension in the radial direction to the extension in the tangential direction is at least 3:1, particularly preferably at least 10:1. The exact structure of the leaf spring elements also depends on the number of leaf spring elements provided. Thus, it is not necessary to compulsorily have three leaf spring elements, which is only the minimum number. In principle, each additional number n of leaf spring elements is also possible (e.g., n = 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.). Of course, increasing the number of leaf spring elements any further becomes uneconomical at some point, resulting in an upper extreme value for the number of leaf spring elements. The spring element shown in Figure 4 can be constructed, for example, from a steel plate with a sheet thickness of 0.5 mm.

[0066] Figure 5 The installation of the spring element 280 is shown by way of example of the spring star shown in Figure 4 . Here, the spring force in the axial direction is generated in such a way that the spring element 280 is pre-assembled. Correspondingly, in Figure 5 , the bending of the leaf spring elements 283 can be seen, while Figure 4 shows the straight leaf spring elements 283 corresponding to the relaxed state of the spring element 280 in Figure 4 . To cause pre-tensioning, the outer ring 282 is installed, for example, in such a way that in the relaxed state of the spring element, the outer ring moves axially relative to the inner ring and in this state the spring element is fixed to the stator unit 130 and the floating bearing 150. The axial movement of the outer ring 282 relative to the inner ring 281 can be adjusted, for example, by inserting spacer elements of different thicknesses (in the axial direction) between the stator unit and the outer ring 282 (depending on the pre-tensioning to be adjusted).

[0067] To prevent unwanted radial clearances from occurring between the floating bearing and the spring element 280 or between the spring element 280 and the stator unit 130, the spring element should be fixedly connected to the stator unit 130 or the floating bearing 150 (e.g., by welding, bonding, screwing, clamping, etc.). It should also be noted that the described pre-tensioned installation of the spring element 280 is carried out in the same way for the spring element as in Figure 4 andFigure 5 is carried out in a structurally different configuration as shown, i.e., for example when the spring element 280 is a disc spring.

[0068] Third Embodiment

[0069] Figures 6 to 8 shows a variant of the third embodiment of the present invention, in which, in addition to the features described separately, there are the same design concepts as in Figure 1 . The basic idea of the third embodiment is to strongly limit the radial movement of the floating bearing relative to the stator unit (i.e., the bearing housing) by applying a radial force to the floating bearing.

[0070] In the first variant shown in Figure 6 of the third embodiment, the same or similar elements as those in Figure 1 are generally denoted by the same reference numerals. Different from Figure 1 , in Figure 6 is also shown a rotating mirror 1000 mounted on the rotor 110, which can, for example, deflect a laser beam in a laser processing device. However, this rotating mirror 1000 is not an essential component of the third embodiment.

[0071] In Figure 6 can be seen a radial spring 600 designed as a helical spring, which bears not only against the stator unit 130 but also against the outer ring 150a of the floating bearing 150 and can thus apply a force to the outer ring 150a of the floating bearing 150 in the radial direction from the outside. Here, the inner ring 150b of the floating bearing 150 is rigidly connected to the rotor 110 as in the design of Figure 1 , while the outer ring 150a has axial mobility relative to the stator unit 130. Due to the spring force acting in the radial direction, the radial mobility of the outer ring 150a relative to the stator unit is restricted. Here, to what extent the axial clearance is also restricted is also related to the spring force. The radial spring 600 generally does not significantly contribute to the axial stiffness of the arrangement structure (which is accomplished by the wave spring), yet ensures small radial mobility with a high radial stiffness. Here, the extension of the radial spring 600 in the radial direction can be adjusted by means of an adjusting screw 610 and thus the desired radial stiffness can be adjusted. The radial spring does not necessarily have to press the floating bearing 150 inward in the radial direction. Specifically, it is also possible that the helical spring is installed in a state in which the helical spring has an increased length relative to the relaxed (force-free) state. In the latter case, the force acts outward in the radial direction on the floating bearing. Particularly possible is to install the spring in the relaxed state and set it to the desired length by means of the adjusting screw 610.

[0072] Figure 7Shows a second variant of the third embodiment, in which the force in the radial direction is applied not by means of a radial spring but by means of a magnet. In Figure 7 In the example, the magnet 700 is fixed to the steering mirror 1000. Only by way of example, the mounting on the back side of the steering mirror is shown. Of course, the magnet 700 can also be mounted at other locations on the part rigidly connected to the rotor. By means of the bow-shaped member 750 protruding into the gap 710, a force is applied to the steering mirror 1000 and thus also to the rotor 110 fixedly connected to the steering mirror, thereby making radial movement significantly more difficult. For this purpose, the bow-shaped member has a magnet or magnetic material at least at the end opposite the magnet 700 in the gap 710. The entire bow-shaped member 750 can in particular also be made of a magnet or magnetized material.

[0073] In Figure 7 In the example shown, the bow-shaped member 750 is fixedly (rigidly) connected to the stator unit 130. In this example, the angular movement of the rotor 110 (and the steering mirror 1000) is restricted to a range of ±20°, which is acceptable in many applications. Preferably, the angular movement of the rotor 110 (and the steering mirror 1000) is restricted to a range of ±10°. The force in the radial direction should be as high as possible and yet not overly strongly restrict the axial mobility, yet also the rotational movement. Starting from this, the inventors have determined that in normal vibrations with accelerations in the range of 5 g to 50 g (g: acceleration due to gravity), the radial force should be five to fifty times greater than the gravity of the system consisting of the rotor and the mirror.

[0074] Of course, instead of the magnet 700, the back side of the steering mirror 1000 can also be covered with a magnetic layer. In addition, the bow-shaped member 750 can be magnetized at least locally, preferably entirely, by means of an electromagnet.

[0075] Figure 8 Shows a third variant of the third embodiment, in particular a cross-section of the rotor 110 and the stator unit 130 with a coil 125 in the radial direction.

[0076] In the variant shown in the third embodiment in Figure 8 In this variant, a radially asymmetric magnetic flux is considered, which magnetic energy results in a radial magnetic force acting on the rotor, thereby strongly restricting the radial mobility relative to the stator unit. In Figure 8 The magnetic rotor 110 (for example a permanent magnet), the coil 125 and the stator unit 130 can be seen, which are constructed asymmetrically because there is an air-filled cavity on one side. As in Figure 8As can be seen, the magnetic field lines are redirected through the cavity 800 in such a way that a radial asymmetry of the magnetic flux is generated. The radially applied force should in turn not exceed approximately five to fifty times the gravity of the system consisting of the rotor 110 and the rotating mirror 1000.

[0077] It is directly understandable that in a third variant of the third embodiment, the rotor can alternatively or additionally have an asymmetrical structure in order to thereby cause or enhance the asymmetry of the magnetic flux.

[0078] Furthermore, it can be seen that combinations of different embodiments are also possible. Only by way of example, the combination of the first embodiment and the second embodiment, the combination of the first embodiment and the third embodiment, or specifically the combination of the first embodiment and the third variant of the third embodiment are mentioned here.

[0079] Finally, it should also be emphasized that the invention in all its embodiments and variants is not limited to the axial preloading of the described floating bearing by means of a spring. It is also conceivable to use a suitable adhesive for the axial preloading of the floating bearing. For example, this is done in such a way that during assembly the floating bearing is axially preloaded by means of a spring and in the preloaded state the adhesive is introduced into the existing gap between the outer ring of the floating bearing and the stator unit. After the adhesive has hardened, the spring used for axial preloading is then removed, so that now the adhesive exerts the preloading force. Here, all materials that still have sufficient elasticity in the hardened state to accommodate the axial movement of the outer ring are considered as adhesives. In particular, the adhesive should not show or only show very little plastic deformation under the influence of the preloading force in the hardened state.

Claims

1. Galvanometer drive device, said galvanometer drive device comprising: a rotor (110) rotatable about a rotation axis (R), said rotor having a magnet; and a stator unit (130) surrounding said rotor (110), said stator unit having a coil (125), said rotor being supported by means of two bearings such that said rotor can perform a rotational movement about the rotation axis (R) relative to said stator unit (130), at least one of said bearings being a floating bearing (150, 155), characterized by radial movement limiting means (170, 280, 600, 750, 800), said radial movement limiting means being adapted to limit the radial movement of said floating bearing (150, 155) with respect to said stator unit (130), said radial movement limiting means being a spring element (280) mounted on said floating bearing (155), by means of which said floating bearing (155) is axially loaded with pressure, said spring element (280) being rigidly fixed to said floating bearing (155) with one section (281) and rigidly fixed to said stator unit (130) with another section (282).

2. The galvanometer driving device according to claim 1, wherein Said floating bearing (150, 155) has an outer ring (150a, 155a), an inner ring (150b, 155b) and a plurality of rolling elements between the inner ring and the outer ring, and said inner ring (150b, 155b) is rigidly fixed to said rotor (110) and said outer ring (150a, 155a) can move in the direction of the rotation axis (R), said radial movement limiting means (170, 280, 600, 750, 800) limits the radial movement of said outer ring (150a, 155a) with respect to said stator unit (130).

3. The galvanometer driving device according to claim 1, wherein, The ratio of the radial stiffness to the axial stiffness on said floating bearing (150, 155) is greater than 10.

4. The galvanometer driving device according to claim 2, wherein, The ratio of the radial stiffness to the axial stiffness on said floating bearing (150, 155) is greater than 10.

5. The galvanometer driving device according to claim 1, wherein, Said spring element (280) has a rotationally symmetric, star-shaped arrangement of n leaf spring elements (283), where n is a natural number greater than or equal to 3.

6. The galvanometer driving device according to claim 5, wherein, The number n of said leaf spring elements (283) is less than or equal to 100.

7. The galvanometer driving device according to claim 6, wherein, The number n of said leaf spring elements (283) is less than or equal to 20.

8. The galvanometer driving device according to claim 6, wherein, The number n of said leaf spring elements (283) is less than or equal to 8.

9. The galvanometer driving device according to claim 1, wherein, Said spring element (280) is configured as a disc spring or a diaphragm spring.

10. The galvanometer driving device according to claim 9, wherein, Said spring element (280) has a movement stiffness in the radial direction, which is greater than the spring stiffness in the axial direction by a factor of at least 50.

11. The galvanometer drive device according to claim 1, wherein, Said spring element (280) has a movement stiffness in the radial direction, which is greater than the spring stiffness in the axial direction by a factor of at least 50.

12. The galvanometer driving device according to claim 11, wherein, Said spring element (280) has a movement stiffness in the radial direction, which is greater than the spring stiffness in the axial direction by a factor of at least 100.

13. The galvanometer drive device according to claim 12, wherein, The spring element (280) has a moving stiffness in the radial direction, which is greater than the spring stiffness in the axial direction by a factor of at least 300.

14. The galvanometer drive device according to claim 10, wherein, The moving stiffness in the radial direction has a value of 4 kN / mm or more and 1000 kN / mm or less.

15. The galvanometer driving device according to claim 14, wherein, The moving stiffness in the radial direction has a value of 20 kN / mm or more and 1000 kN / mm or less.

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