Sensor device and method for determining a kinematic quantity of a relative motion

Abstract

An optoelectronic encoder device (10) for determining a kinematic quantity of a relative motion of a first object to a second object is described, wherein the encoder device (10) comprises a physical object (14) connectable to the first object and having at least one code track (16), a scanning unit connectable to the second object with a light emitter (20) for illuminating or shining light (30) onto or through the physical object (14) in the area of ​​the code track (16) so that a light pattern is generated, and with a light receiver (24) for generating a received signal from the light pattern incident on the light receiver (24), as well as a control and evaluation unit (28) configured to determine the kinematic quantity from the received signal. The scanning unit includes an adaptive lens (22).

Description

[0001] The invention relates to a sensor device and a method for determining a kinematic quantity of a relative motion according to the preamble of claim 1 and 14, respectively.

[0002] Encoder devices are classified as either linear or rotary systems. A linear encoder determines a displacement along an axis. A rotary encoder, also known as a rotary angle sensor or encoder, is used to detect an angle of rotation or angular position, for example, of a shaft in a drive element. An important application is in motor feedback systems, where the rotary encoder in a servo motor reports the actual rotational speed back to the control system.

[0003] In this process, a measuring element is scanned, which is mounted along the linear axis or rotates with the shaft. In an optical measuring principle, and particularly a projection principle, a modulator is illuminated by a light source with a measuring element, and this intensity-modulated light is detected by a light receiver. The modulator is, for example, a rotating code disk that, as a measuring element, has optically transparent and opaque areas for transmitted light and reflective and absorbing areas for reflected light. The areas or code elements can be openings, reflective and diffractive structures, prisms, structures varying in transmittance, reflectivity, gray tone, or color, and other optically distinguishable elements.Together, the code elements form a measurement track, thereby creating an illumination pattern and, through rotation, a local modulation of the light incident on the light receiver. This principle can be transferred to a physical object for length measurement, which, of course, does not rotate but instead undergoes a relative movement in the longitudinal direction.

[0004] The corresponding modulated received signal from the light receiver is evaluated to obtain the desired position information. Incremental sine / cosine encoders are particularly common; these generate a sine and a cosine signal each using two receiving elements with a 90° phase shift. However, incremental systems with more receiving elements also exist, for example, to obtain differential signals with additional negative sine and cosine signals, with other phase differences such as 120°, or with other non-sinusoidal modulations. Furthermore, absolute encoder devices are known that use various unique codes to detect absolute positions, not merely displacements or changes. Often, there is more than one scanned measurement track, for example, an absolute and an incremental track.

[0005] The light from the light source, used to illuminate or pass through the modulator, is typically adapted by a lens to the requirements of the scale and detection arrangement, and is collimated or parallelized for this purpose. This beam shaping ensures proper function and the best possible signal quality. However, tight mechanical tolerances must be maintained for this beam shaping. It is very difficult from a manufacturing standpoint to maintain tolerances on the transmitter side in the range of less than 10 µm, so in practice, variations occur during the production of the illumination unit. If the distance between the light source and the lens is not optimal, the collimation is not ideal; in other words, an undesirable divergent or convergent beam path occurs after the lens.This reduces the signal contrast, and the already very tight and sensitive distance tolerance between the scale and the detector, which is also in the range of less than 10 µm, is further reduced. The homogeneity of the illumination intensity across the illuminated area also decreases, which further negatively impacts signal quality.

[0006] From DE 691 11 943 T2, an optical coding device is known, comprising a light source, a light detection device, and a lens plate in between. The rotation of the lens plate is measured based on the light pattern passing through the ring-shaped lens arrangement. A collimator lens is associated with the light source for collimating the emitted light.

[0007] Focus adjustments are known from technical fields outside of encoder devices, typically used to adjust the focal length, i.e., the distance between the light receiver and the lens or between the light source and the lens. However, this is far too complex and bulky for a rotary encoder. Lenses are also known in which the shape, and thus the focal length, of the lens itself is directly varied by means of voltage control. This, too, has not yet found any application in encoder devices of this type.

[0008] Examples of lenses with variable focal length include gel and liquid lenses. In a gel lens, a silicone-like liquid is mechanically deformed using piezoelectric or inductive actuators. Liquid lenses, for example, utilize the so-called electrowetting effect by placing two immiscible liquids on top of each other in a chamber. When a control voltage is applied, the two liquids change their surface tension in different ways, so that the curvature of the inner interface between the liquids changes depending on the voltage.

[0009] In further development of such liquid lenses for focus adjustment, EP 2 071 367 A1 proposes also changing the tilt of the liquid lens by applying different voltages in the direction of rotation. To prevent the recording of blurry images, the camera's own movement is then determined, and one or more lenses in the camera are tilted to counteract this movement. Image stabilization is not relevant for a rotary encoder, would not be transferable in this way, and would not solve the described problem of impaired signal quality due to tolerances.

[0010] German patent DE 10 2005 015 500 A1 discloses another optoelectronic sensor with a liquid lens whose beam-shaping properties can be asymmetrically modified by an asymmetric frame or different electrical potentials at separate electrodes of the lens frame. However, the document does not explain what this can be used for.

[0011] German patent DE 10 2005 040 772 B4 deals with optical length measurement using a liquid lens. However, this form of length measurement has nothing to do with a conventional encoder device, as no physical object is being scanned. Rather, as in an optical mouse, movement within a scene is detected using spatial frequency methods or optical flow. Furthermore, the liquid lens is not located in the illumination unit, but rather in an image capture lens, and in this position, it cannot, in principle, contribute to signal improvement in the case of design tolerances in the illumination unit of a encoder device.

[0012] German patent DE 20 2012 105 023 U1 discloses a handheld laser distance measuring device with a liquid lens on both the transmitting and receiving sides. The liquid lenses serve to focus and / or change the direction of transmission of the measuring signal. Specifically, the patent describes how operator tremors are compensated for by appropriately controlling the liquid lenses.

[0013] It is therefore an object of the invention to improve the determination of a kinematic quantity using a sensor device.

[0014] This problem is solved by a sensor device and a method for determining a kinematic quantity of a relative motion of a first object to a second object according to claim 1 and 12, respectively. The two objects are movable relative to each other in a longitudinal or rotational direction, and the corresponding position or angular orientation is to be measured. A physical object with at least one elongated or circular scale or code track is connectable to the first object, and a scanning unit for scanning the physical object is connectable to the second object. In the assembled state during application, the relative motion of the objects is transferred to a relative motion between the physical object and the scanning unit. The terms "first object" and "second object" are interchangeable.The encoder device is also referred to as a linear encoder in the case of linear motion, as a rotary encoder, angle sensor, or encoder in the case of rotational motion, and, when used in a servo motor, particularly as a motor feedback system. The first object is then preferably a shaft, and the second object is a stationary part or housing of the rotary encoder. Quantities such as velocity or angular velocity can be derived from the position or angular position.

[0015] In the scanning unit, a light source generates transmitted light that illuminates or shines through the measuring instrument in the area of ​​the code track. The resulting light pattern differs depending on the relative position of the measuring instrument, which, as described in the introduction, therefore acts as a modulator with its code track. The light pattern falls onto a light receiver and generates a corresponding received signal. Preferably, the light receiver has several light receiving elements and consequently generates several received signals. A control and evaluation unit processes the received signal(s) to determine the desired kinematic quantity of the relative motion. This can be the incremental and / or absolute position or a derived quantity, for example, a velocity or acceleration determined by derivation.

[0016] The invention is based on the fundamental idea of ​​using an adaptive lens in the transmitter device. An adaptive lens can be changed in its focal length and / or orientation. With the aid of the adaptive lens, the beam path of the transmitted light or the light pattern in the transmitter device can be adjusted.

[0017] The invention offers the advantage of creating optimal lighting conditions. This improves the signal-to-noise ratio and ultimately the robustness and accuracy of the kinematic measurement. Unlike a rigid lens, the adaptive lens allows for the simple compensation of manufacturing tolerances, thus simplifying the production of the sensor device and reducing costs. The optimized beam shaping achieved with the adaptive lens can affect the beam cross-section and preferably also ensures the most homogeneous light distribution possible across the illuminated area.

[0018] The light source is preferably located on one side of the measuring instrument and the light receiver on the other side. Sampling thus occurs in transmission or projection. In this case, a suitable beam shaping is particularly important. However, an alternative sampling method using reflection with the light source and light receiver on the same side of the measuring instrument is also possible.

[0019] The code elements of the code track are preferably designed as code slots or code reflectors. This corresponds to transmissive or reflective scanning in transmitted or reflected light. The code elements preferably form an absolute or an incremental encoding. The invention is therefore applicable to both types of encoding.

[0020] The adaptive lens is preferably positioned between the light source and the measuring scale. The beam shaping of the transmitted light therefore takes place before the transmitted light falls onto the code track.

[0021] The adaptive lens is preferably a liquid lens or a gel lens. Such lenses are available as components, offer the desired adjustment options, and are very small and cost-effective.

[0022] The adaptive lens is preferably adjusted to collimate the transmitted light. This results in particularly advantageous beam shaping and a particularly good signal, and collimated light allows for greater distance tolerance on the receiving end. While collimation is often also the goal with a conventional rigid lens, this is only achieved in practice if the components are mounted under very tight tolerances. This is at least expensive and, depending on the requirements, not even fully achievable. The adaptive lens according to the invention, on the other hand, enables collimation even while compensating for the actual tolerances in the installed state.

[0023] The adaptive lens is preferably set to focus or diffuse the transmitted light. This deliberately deviates from collimation and does not necessarily result in better beam shaping. However, stretching or compressing the light pattern may compensate for additional adjustment tolerances without excessively impairing signal quality. For a diffused transmitted light beam, the adaptive lens does not necessarily need to be able to assume a negative focal length; rather, it may be the case that an initial divergence of the light source is only partially compensated for by the adaptive lens.

[0024] The adaptive lens is preferably designed to be tiltable, so that the direction of the emitted light can be changed by controlling the adaptive lens. The control and evaluation unit can control the adaptive lens accordingly and thus adjust the direction of the emitted light. This is another way to compensate for adjustment tolerances. The tilting does not refer, or at least not necessarily refers, to a geometric tilting, but rather to the optical effect, which effectively corresponds to a tilting. The effect is a shift of the light pattern along the code track or perpendicular to it; that is, in the case of a rotary encoder, a shift in the circumferential direction and / or radially, and in the case of a length measurement, a shift in the longitudinal direction or perpendicular to it.

[0025] The adaptive lens preferably features control elements segmented in the direction of rotation. These control elements are, for example, segmented electrodes that control a liquid lens via the electrowetting effect. Segmented actuators are also conceivable, particularly piezoelectric actuators, which locally alter the pressure on a liquid and thereby cause a membrane to curve differently on the liquid, or which directly deform a gel-like substance within the lens. The segmentation in the direction of rotation enables a non-rotationally symmetrical manipulation of the lens, resulting in the optical tilt.

[0026] The control and evaluation unit is preferably configured for a calibration mode in which the focal length and / or orientation of the adaptive lens is changed. Calibration in this mode can be performed at the factory, for example, during final assembly, or alternatively during commissioning, maintenance, or even during operation, preferably during a temporary shutdown. The aim of the calibration is to find and adjust an optimal position of the adaptive lens for optimal beam shaping and thus compensate for initial tolerances or tolerances that may have arisen during operation. The calibration preferably takes place in several relative positions of the scale and the scanning unit.

[0027] The control and evaluation unit is preferably designed to determine the level of the received signal and, in particular, to optimize it using the adaptive lens. The typical optimization goal is a maximum level under otherwise identical conditions that promises the best signal-to-noise ratio. The current setting of the adaptive lens can be evaluated based on the received signal, especially its level. By evaluating the level, automatic calibration is possible, which tests various settings of the adaptive lens and ultimately selects the setting that maximizes the level. This can even be extended to a control system.

[0028] The control and evaluation unit is preferably designed to vary the focal length and / or alignment of the adaptive lens for self-testing, evaluate the respective received signal, and, if necessary, issue a maintenance or pre-failure message. This can be classified as condition monitoring. The aim is to check the condition of the encoder device in order to issue a maintenance or pre-failure message in a timely manner if necessary. For example, the code disc spacing can be measured by varying the focal length during operation or during a break in operation.

[0029] The control and evaluation unit is preferably designed to compare the respective received signal with a previously stored reference signal, which was acquired in a target state of the encoder device, in particular a received level and a reference level, each with the same control of the adaptive lens. The encoder device therefore includes a memory, in particular a memory of the control and evaluation unit, in which an expectation of an intact encoder device is stored in the form of at least one reference signal. Several reference signals for different positions of the adaptive lens can be stored. Under otherwise comparable boundary conditions, especially with regard to relative movement, the respective received signal should correspond to this expectation. Otherwise, a fault in the encoder device is suspected and a corresponding message is issued.The comparison preferably takes place at the level of levels or amplitudes; accordingly, reference levels are stored instead of entire time-dependent reference signals.

[0030] The light receiver preferably has at least one test light receiving element to check the beam shaping of the transmitted light. In this embodiment, there is at least one dedicated test light receiving element or at least one photodiode that serves only to check the setting of the adaptive lens. This has the advantage that the arrangement, connection, type, and evaluation of the test light receiving element are tailored to this task and there are no interactions with the actual measurement task. Alternatively, at least one existing light receiving element of the light receiver is used in a dual function for checking the setting of the adaptive lens.

[0031] The encoder device is preferably designed as a rotary encoder. In a rotary encoder, the relative movement of the measuring element, which is then also referred to as a code disk, is a rotation, and the code elements are arranged on a circle for each track. In an alternative length measuring system, the measuring element is elongated, with the code elements of a track arranged on a straight line. The use of an adaptive lens according to the invention is advantageous in both cases.

[0032] The method according to the invention can be further developed in a similar manner and thereby exhibits similar advantages. Such advantageous features are described by way of example, but not exhaustively, in the subclaims following the independent claims.

[0033] The invention will be explained in more detail below with regard to further features and advantages, using exemplary embodiments and with reference to the accompanying drawings. The figures of the drawing show: Fig. 1 a schematic representation of a rotary encoder; Fig. 2a a representation of the beam path of collimated transmitted light at an adaptive lens in a transmitter device at a target distance between light source and measuring instrument; Fig. 2b a representation similar Fig. 2a, however, with too short a distance between light source and measuring instrument and compensation by a smaller focal length of the adaptive lens; Fig. 2c a representation similar to Fig. 2a, however, with too large a distance between light source and measuring instrument and compensation by a larger focal length of the adaptive lens; Fig. 3a a representation of the beam path of collimated transmitted light at an adaptive lens in a transmitter device in a target arrangement of light source and measuring instrument; Fig. 3b a representation similar Fig. 3a, however with beam widening due to the shorter focal length of the adaptive lens; Fig. 3c a representation similar to Fig. 3a, however with beam focusing due to the longer focal length of the adaptive lens Fig. 4a a representation of an adaptive lens in a beam-widening setting; Fig. 4b a representation of the adaptive lens in a neutral setting; Fig. 4c a representation of the adaptive lens in a beam-focusing setting; Fig. 5a a representation of the adaptive lens with downward tilt; Fig. 5b a representation of the adaptive lens without tilting; and Fig. 5c shows a representation of the adaptive lens with upward tilt.

[0034] Fig. Figure 1 shows a schematic representation of a encoder device 10, which is designed as a rotary encoder, for example, for a motor feedback system. The encoder device 10 has a code disk rotating with the shaft 12 as a scale 14, and on the scale 14 is a code track 16 with a plurality of code elements 18. The code track 16 can be an incremental code track or a more complex code track, for example, for absolute positioning. Furthermore, contrary to the simplified representation, several code tracks can be provided.

[0035] A light source 20 on the circumference of the measuring instrument 14, for example an LED, emits transmitted light onto the measuring instrument 14 through a transmitting optic with an adaptive lens 22. The adaptive lens 22 is variable in its focal length and / or tilt direction; this function will be explained in more detail later with reference to the other figures. In other embodiments, the transmitting optic has, in addition to the adaptive lens 22, further optical elements, such as at least one additional concave or convex lens, at least one deflecting element, or an aperture.

[0036] The beam-shaped transmitted light is modulated by the code elements 18. For this purpose, the code elements 18 are designed as code slots or, more generally, as transparent areas. Thus, in Fig. 1. Below the scale 14, a light pattern consisting of light-dark transitions is projected, depending on the rotational position of the scale 14. The light pattern falls onto a light receiver 24 with one or more light-receiving elements 26, preferably in a row. The light receiver 24 is, for example, configured as an opto-ASIC (application-specific integrated circuit) or with discrete photodiodes.

[0037] During the rotation of the measuring element 14, modulated received signals are generated, which are evaluated by a control and evaluation unit 28 to determine the angular position of the measuring element 14 and, depending on the embodiment, other kinematic quantities. Depending on the measuring element 14 and code track 16, various measurements are conceivable, in particular incremental and / or absolute position determination. In contrast to Fig. 1. Multiple code tracks 16 can also be combined into one measurement or for multiple measurements, for example to perform both incremental and absolute position determination.

[0038] The representation of the encoder device 10 in Fig. Figure 1 is very schematic. Therefore, the design of the scanning unit with light transmitter 20, adaptive lens 22 and light receiver 24 is shown in Fig. 1. kept very simple. In particular, with regard to the dimensions and specific positions of the components, the encoder device 10 can vary considerably in practice. Fig. 1. As an alternative to a transmissive setup, a reflective setup is also conceivable, in which light transmitter 20, adaptive lens 22 and light receiver 24 are located on the same side of the physical body 14 and the code elements 18 have reflective properties.

[0039] The encoder device 10 can also be configured as a linear encoder or longitudinal measuring system instead of a rotary encoder. In this case, the measuring element 14 is not circular but elongated, the measuring track is arranged accordingly on a straight line instead of a circle, and the movement occurs longitudinally instead of rotating.

[0040] Fig. Figure 2a shows the beam path of the transmitted light 30 generated by the light source 20. In this embodiment, collimated, i.e., parallelized, transmitted light 30 is desired, as shown. However, this requires, with respect to an initially fixed focal length setting of the adaptive lens 22, strict adherence to tolerance specifications for the arrangement and alignment of the components relative to each other, typically on the order of only a few ten micrometers.

[0041] With the adaptive lens 22, which is, for example, a liquid or gel lens and can alternatively be constructed using any other known technology, collimated transmitted light 30 can be achieved even for differing relative arrangements that vary by more than the specified tolerances. The focal length of the adaptive lens 22 can be changed by the control and evaluation unit 28 by appropriate control, for example, by applying a control voltage. With a suitable focal length, the beam shaping of the transmitted light 30 can be optimally adjusted to the system requirements. Therefore, the collimation, in particular, can be correctly adjusted or corrected even after the system has been assembled, which is subject to tolerances. The assembly tolerances discussed are thus considerably increased. With the adaptive lens 22, the Fig. 2a should also be understood to mean that the appropriate focal length for the given constellation was found and set, instead of imagining the focal length as fixed as initially assumed.

[0042] Fig. 2b shows, for comparison, a representation analogous to Fig. 2a the beam path of the transmitted light 30 generated by the light source 20 in a transmitter device 10, in which, due to tolerances after assembly, the distance between the light source 20 and the scale 14 or code track 16 became too small. By adjusting the focal length of the adaptive lens 22, this can be compensated for and collimated transmitted light 30 can still be generated.

[0043] Fig. Figure 2c shows the opposite situation, in which, due to tolerances after assembly, the distance between light source 20 and measuring instrument 14 or code track 16 became too large. This is now compensated for by a shorter focal length of the adaptive lens 22 in order to still generate collimated transmitted light 30.

[0044] The collimation achieved, or, with reference to further embodiments to be presented, more generally the beam shaping achieved, can be verified using at least one special photodiode of the light receiver 24 (not shown separately). This allows for the implementation of an automatic process or even a type of control to achieve a desired beam shape of the emitted light 30. Alternatively, at least one light receiving element 26 of the light receiver 24 can be used instead of a dedicated special photodiode. For example, a level is maximized for calibration, i.e., for adjusting the adaptive lens 22 accordingly. The adjustment of the beam shaping of the emitted light 30 can be performed once during manufacturing, commissioning, maintenance, or continuously or cyclically during operation.

[0045] The Fig. Figures 3a-c illustrate an alternative embodiment in which the transmitted light 30 is not collimated but bundled or scattered. Fig. 3a is the same representation as the Fig. 2a and is for comparison purposes only. In Fig. In 3b, the transmitting light 30 after the adaptive lens 22 has a divergence, in Fig. 3c a convergence. It should be noted that a negative focal length is not required for a divergence, although this is not excluded, as it is sufficient if only the original divergence of the transmitted light at the light source 20 is not completely compensated. The deliberate deviation from collimation serves, for example, to compensate for an incorrect position or arrangement of the light receiver 24 by stretching or compressing the projection of the scale 14 or the light pattern accordingly. Alternatively, a misalignment in the direction of the code track 16 or perpendicular to it can be compensated by tilting the adaptive lens 22 in its viewing direction. Such an adaptive lens is finally described with reference to the Fig. 5a-c presented.

[0046] The Fig. 4a-c and Fig. Figures 5a-c show an exemplary embodiment of the adaptive lens 22 as a liquid lens based on the electrowetting effect. The operating principle is explained in more detail using such a liquid lens as an example, but the invention also encompasses other adaptive lenses, for example, those with a liquid chamber and a membrane covering it, the curvature of which is changed by pressure on the liquid, lenses with a gel-like, optically transparent material that is mechanically deformed by an actuator, or lenses with other deformable surfaces.

[0047] In this embodiment, the adaptive lens 22, acting as a liquid lens, comprises two transparent, immiscible liquids 32 and 34 with different refractive indices but the same density. The shape of the liquid-liquid interface 36 between the two liquids 32 and 34 is used for the optical function. Actuation is based on the principle of electrowetting, which exhibits a dependence of the surface or interfacial tension on the applied electric field. Therefore, it is possible to change the shape of the interface 36, and thus the optical properties of the adaptive lens 22, by electrically controlling it at a terminal 38, thereby applying corresponding voltages to an electrode 40.

[0048] The Fig. Figures 4a-c first show the change in the focal length of the adaptive lens 22. In Fig. 4a Incident transmitted light 30 is scattered at a concave boundary layer 36. Fig. Figure 4b shows a neutral setting with a flat boundary layer 36, while in Fig. 4c the boundary layer is convex and thus focuses the incident transmitted light 30°. It is clear that by means of appropriate intermediate settings the refractive behavior can be more finely graduated and thus a desired focal length can be set. In the Fig. Parallel light is already incident on 4a-c, while the transmitted light 30 is typically initially divergent. This does not imply any limitation with the Fig. Figures 4a-c illustrate different focal lengths of the adaptive lens 22 only by way of example.

[0049] The adaptive lens 22 can preferably be influenced in its tilt. This is described in the Fig. Figures 5a-c illustrate this and are based on non-rotationally symmetrical voltages and thus electric fields. Accordingly, the boundary layer 36 is not deformed rotationally symmetrically, which is exploited for the tilting. Fig. 5a shows a downward tilt of the adaptive lens 22, Fig. 5b a rotationally symmetrical setting without tilting for comparison, and Fig. 5c is a tilting of the adaptive lens 22 upwards. The direction of the tilt refers to the optical effect, i.e., from which transmitted light 30 is received or in which direction transmitted light is emitted. A focal length setting can be superimposed on the tilt.

Claims

[1] Optoelectronic encoder device (10) for determining a kinematic variable of a relative movement of a first object to a second object, wherein the encoder device (10) a measuring embodiment (14) connectable to the first object with at least one code track (16), a scanning unit connectable to the second object, comprising a light transmitter (20) for illuminating or transilluminating the measuring standard (14) with transmitted light (30) in the region of the code track (16) so that a light pattern is created, and comprising a light receiver (24) for generating a received signal from the light pattern incident on the light receiver (24) and a control and evaluation unit (28) which is designed to determine the kinematic variable from the received signal, characterized by , that the scanning unit has an adaptive lens (22), wherein the control and evaluation unit (28) is designed to vary the focal length and / or orientation of the adaptive lens (22) for a self-test, to compare the respective received signal with a previously stored reference signal which was detected in a desired state of the transmitter device (10), and to output a maintenance or pre-failure message if necessary. [2] Transmitter device (10) according to claim 1, wherein the light transmitter (20) is arranged on one side of the measuring embodiment (14) and the light receiver (24) is arranged on the other side of the measuring embodiment (14). [3] Transmitter device (10) according to claim 1 or 2, wherein the adaptive lens (22) is arranged between the light transmitter (20) and the measuring embodiment (14). [4] Transducer device (10) according to one of the preceding claims, wherein the adaptive lens (22) is a liquid lens or a gel lens. [5] Transducer device (10) according to one of the preceding claims, wherein the adaptive lens (22) is adjusted so that the transmitted light (30) is collimated. [6] Transmitter device (10) according to one of claims 1 to 4, wherein the adaptive lens (22) is adjusted so that the transmitted light (22) is bundled or scattered. [7] Transmitter device (10) according to one of the preceding claims, wherein the adaptive lens (22) is designed to be tiltable, so that the radiation direction of the transmitted light (30) can be changed by controlling the adaptive lens (22). [8] Transducer device (10) according to one of the preceding claims, wherein the control and evaluation unit (28) is designed for a calibration mode in which a focal length and / or an orientation of the adaptive lens (22) is changed. [9] Transducer device (10) according to one of the preceding claims, wherein the control and evaluation unit (28) is designed to determine a level of the received signal and in particular to optimize it by means of the adaptive lens (22). [10] Transmitter device (10) according to one of the preceding claims, wherein the light receiver (24) has at least one test light receiving element in order to check the beam shaping of the transmitted light (30). [11] Encoder device (10) according to one of the preceding claims, wherein the encoder device (10) is designed as a rotary encoder. [12] Method for determining a kinematic variable of a relative movement of a first object to a second object, wherein a measuring embodiment (14) with at least one code track (16) is connected to the first object and a scanning unit with a light transmitter (20) for illuminating or transilluminating the measuring embodiment (14) with transmitted light (30) in the region of the code track (16) is connected to the second object, and is connected to a light receiver (24) for generating a received signal from the light pattern incident on the light receiver (24), and the kinematic variable is determined from the received signal, characterized bythat a beam formation of the transmitted light (30) takes place with an adaptive lens (22), that for a self-test the focal length and / or alignment of the adaptive lens (22) is varied and the respective received signal is compared with a previously stored reference signal which was detected in a desired state of the transmitter device (10), and that if necessary a maintenance or pre-failure message is output.

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