Measuring device

Abstract

The present invention provides an encoder module (100) for mounting on a machine to measure the relative displacement between a first and second part of the machine, and a method for configuring the encoder module. The encoder module comprises a scale (202) and a guided scale signal receiver (304) including a read head (300) coupled to a mount (302). The encoder module (100) is configured to determine and output information indicating the relationship between the mount (302) and the guided scale signal receiver (304).

Description

Technical Field

[0001] The present invention relates to an encoder device. For example, the present invention relates to what is generally known as a guided encoder and also generally known as an integrated bearing encoder.

Background Art

[0002] Encoders are used in many industries to provide position (or derivatives thereof, such as velocity and / or acceleration) feedback to a machine's control system. For example, feedback control of the relative position / motion between machine components can be mentioned. As is understood, usually a scale is provided on a part of the machine, and a read head for reading that scale is arranged on another part. Thereby, the read head can detect the relative position between the scale and the read head along the measurement axis of the encoder, and thus the relative position of the machine components.

[0003] There are many configurations for the arrangement of the scale and the read head of the encoder. For example, the scale signal receiving part of the read head can be configured to deflect / contact the scale and / or parts of the protective housing to which the scale is attached. Thus, a sealed encoder module can include an "integrated bearing" (and thus becomes what is called an "integrated bearing" or "guided" encoder module). Other examples of integrated bearing / guided encoders include embodiments in which a bearing is arranged between a scale signal receiver (or a part with which the scale signal receiver has a fixed relationship) and a scale or a part with which the scale has a fixed relationship. However, it is not necessarily this configuration, and the encoder does not necessarily have to be an integrated bearing encoder / guided encoder. For example, the arrangement of the scale signal receiver inside the protective housing can be independent of the scale and the protective housing. Thus, the encoder module can be expressed as an "integrated bearingless" or "bearingless" encoder module.

[0004] Depending on the technology employed by the encoder, the operating environment may need to be clean and free from contaminants (e.g., dust, dirt, moisture (oily and / or watery, etc.)). Scale and / or contamination on the readhead can adversely affect the performance of the encoder. In many industrial sectors, machines using encoders operate in a properly clean environment, making it possible to use so-called "exposed encoders" (or "open encoders").

[0005] However, there are cases, such as in the machine tool industry, where the working environment is not clean and liquid and solid waste is prevalent. In such cases, there may be a need to protect the encoder scale and read head from these harmful environments. Typically, in such situations, a type of encoder commonly called a sealed (also known as enclosed) encoder is used. Such a sealed / enclosed encoder includes the scale and read head and has a protective housing that encloses at least the scale signal receiving portion of the scale and read head as a single unit, and the whole thing is supplied and installed as a single module. Enclosed encoders are either guided encoders or bearingless encoders.

[0006] International Publication 2017 / 093738 discloses a sealed encoder in which a readhead receives a scale signal and outputs diagnostic information relating to that scale signal.

[0007] European Patent Application Publication No. 2645068 discloses a readhead control mechanism for controlling a readhead included in an optical encoder configured to measure the mechanical displacement between a fixed part and a movable part by reading a scale on a fixed part using a readhead provided on the movable part.

[0008] The present invention provides an improved encoder device. In particular, the present invention relates to an improvement of a guided encoder. For example, according to the present invention, an encoder module is provided which includes a scale and a read head including a guided scale signal receiver.

[0009] According to a first embodiment, an encoder module is provided for mounting on a machine to measure the relative displacement between a first part and a second part of the machine. The encoder module comprises a read head including a scale, a guided scale signal receiver, and a mount, and the encoder module is configured to determine and output information indicating the relationship between the mount and the guided scale signal receiver. The encoder module may be a sealed encoder module. The mount may be a mounting block.

[0010] By providing information about the relationship (i.e., the (relative) positional relationship) between the first part of the readhead (i.e., the guided scale signal receiver) and the second part (i.e., the mount), it becomes possible to monitor the positional relationship between the guided scale signal receiver and the mount as the readhead moves relative to the scale and the guided scale signal receiver is guided by the scale.

[0011] Additionally, the information is diagnostic information. The relationship may be a positional relationship. The relationship may be a distance, for example, the distance between the mount and the guided scale signal receiver (e.g., the distance along the direction perpendicular to the scale surface) and / or the lateral distance (in the direction perpendicular to the direction perpendicular to the scale measurement direction and the direction perpendicular to the scale surface). The positional relationship may additionally or alternatively be pitch and / or roll and / or yaw. Additionally, the relationship may be radial and / or axial displacement and / or swash.

[0012] An integrated protective housing may be provided. The integrated protective housing may enclose at least a portion of the guided scale signal receiver. The integrated protective housing may enclose at least a portion of the mount. The integrated protective housing may enclose the guided scale signal receiver and at least a portion of the mount. Additionally, the integrated protective housing encloses at least a portion of the mount and the entire scale signal receiver.

[0013] Information relating the mount and the guided scale signal receiver may include information obtained directly and / or indirectly about the relationship between the mount and the scale.

[0014] Information relating the mount to the guided scale signal receiver may include information obtained directly and / or indirectly regarding the relationship between the mount and the guided scale signal receiver.

[0015] Information relating the mount and the scale may include (i) the relationship between the mount and the scale, and / or (ii) the relationship between the mount and the guided scale signal receiver, and / or (iii) the relationship between the mount and the protective housing.

[0016] By providing information indicating the relationship between the mount and the guided scale signal receiver, optimal alignment of the mount and scale can be more easily achieved. Optimal alignment of the mount and scale can partially reduce the force acting between the scale and the guided scale signal receiver. By partially reducing the force acting between the scale and the guided scale signal receiver, wear on the guide mechanism / bearings of the scale and / or guided scale receiver can be reduced, which can extend the operating life of the encoder module.

[0017] Additionally, the read head is configured to determine and output the aforementioned information.

[0018] The encoder module may include at least one output device for outputting the information in the form of a human-perceptible signal. The output device may include a visual output device, which may be configured to emit an optical signal. The output device may include an acoustic output device, which may be configured to emit an acoustic signal. The at least one output device may be provided on the read head, or additionally on a mount.

[0019] The mount further includes a mounting portion provided on the outside of the protective housing, which attaches the mount to either a first or second moving part of the machine, and the output device is provided on the mount. Alternatively, the at least one output device may be provided on the protective housing.

[0020] The protective housing additionally includes at least one elastic seal through which the lead head can protrude, thereby enabling the inductive signal receiver to be mounted on a machine component.

[0021] The scale may include a rotary scale. The encoder module may include an optical scale and a read head. The encoder module may include a magnetic scale and a read head. The encoder module may include a capacitive scale and a read head. The encoder module may include an inductive scale and a read head.

[0022] Furthermore, a machine including a sealed encoder module according to a first aspect of the present invention is disclosed.

[0023] A second aspect of the present invention provides a method for setting up an encoder module for measuring the relative positions of two relatively movable parts of a machine in a first degree of freedom, the encoder module including a scale and a guided scale signal receiver, and a read head coupled to a mount, the encoder module being configured to determine and output information, the method including using the information to determine whether the scale signal receiver and the mount are in a desired relative positional relationship in at least one degree of freedom other than the first degree of freedom.

[0024] The information may be diagnostic information. The information may be information that can be used to determine the relative positional relationship between the scale signal receiver and the mount. The relationship may be a positional relationship. The relationship may be a distance (e.g., the distance between the mount and the guided scale signal receiver (e.g., the distance along the direction perpendicular to the scale plane) and / or the lateral distance (in the direction perpendicular to the scale measurement direction and the direction perpendicular to the scale plane)). The positional relationship may additionally or alternatively be pitch and / or roll and / or yaw. The relationship may additionally be radial and / or axial displacement and / or swash.

[0025] Additionally, an integrated protective housing that encloses at least the scale and at least a portion of the scale signal receiver.

[0026] Also disclosed is an encoder module for mounting on a machine to measure the relative displacement between a first and second part of the machine. The encoder module may include a scale and a read head. Additionally, the read head may include a guided scale signal receiver and a mount. The encoder module may be configured to determine and output information. The information may be diagnostic information. The information may indicate the relationship between the mounting part and the guided scale signal receiver. The encoder module may be a sealed encoder module. The relationship may additionally be a positional relationship. [Brief explanation of the drawing]

[0027] The present invention is described only by the following examples.

[0028] [Figure 1(a)] It is a figure showing a cross-sectional example of a conventional guided sealed encoder. [Figure 1(b)] It is a figure showing a cross-sectional example of a conventional guided sealed encoder. [Figure 2] It is a figure showing a schematic diagram of the prior art encoder of FIG. 1. [Figure 3] It is a figure schematically showing a first embodiment of an encoder. [Figure 4] It is a figure schematically showing a second embodiment of an encoder. [Figure 5] It is a figure schematically showing a third embodiment of an encoder.

Mode for Carrying Out the Invention

[0029] Figure 1 shows a prior art guided encoder 10, which includes a first part 20 attached to a first part of a machine and a second part 30 attached to a second part of the machine and capable of relative movement to the first part in a first direction, i.e., the measuring direction. In this example, the guided encoder is a sealed encoder, and the first part 20 includes a scale 22. The first part 20 further includes a protective housing 24 and a sealing lip 26. The scale 22 is fixedly mounted to the protective housing, and the protective housing is sealed by the sealing lip 26. The scale 22, protective housing 24, and sealing lip 26 all extend in the measuring direction. In the illustrated embodiment, the second part 30 is a read head 30 including a mount (in the form of a mounting block 32 in the present embodiment) and a scale signal receiver 34, in particular a guided scale signal receiver 34. Figure 1(b) shows a light source 36 and a scale signal receiver 38. As is clear from the figure, light from the light source 36 passes through the scale 22, and its signal is received by the scale signal receiver 38. As light passes through the scale 22, it interacts with the scale, and this interaction is carried out by one of several methods well known to those skilled in the art, including diffraction, shadowing, imaging, induction, capacitance, and encoders based on magnetic effects, as well as by methods of operating the encoder. Figure 1(b) also shows a first spring 44 that presses a guided scale signal receiver 44 against the scale 22 via a bearing 41. In this embodiment, the bearing 41 is located on the scale on the same side as the mounting block 32.

[0030] Referring to Figure 2, a schematic diagram of the conventional encoder shown in Figure 1 is displayed. The scale 22 extends in the direction of the scale indicated by arrow 28, and the scale signal receiver 34 is attached to the scale 22 by multiple bearings (bearing 41, Figure 1(b)), so that the signal receiver 34 is movable relative to the scale 22 in direction 28 while maintaining a fixed relationship with the scale in other directions. The read head 30, which is attached to the second part of the machine, is designed to move relative to the scale in the direction indicated by arrow 37. When in use, the mounting block 32 of the read head 30 is fixed to the second part of the machine, so that the read head 30 moves relative to the scale 22 in direction 37. As a result of the relative movement of the mounting block 32 and the scale 22, the scale signal receiver 34 of the read head moves relative to the scale 22 in direction 28.

[0031] Directions 28 and 37 are preferably parallel, but this is not always the case, and slight deviations from parallelism may occur, which may be related to the movement of the first and second parts of the machine to which the encoder device is mounted. To mitigate the effects of deviations in directions 28 and 37, the scale signal reader 34 is movable relative to the mounting block 32 by rotating in the direction indicated by arrow 42 around point 40. In the illustrated embodiment, to enable pivoting in direction 42, a portion 39 of the mounting block 32 extends into the scale signal receiver 34 and is pivot-supported at point 40. In the illustrated embodiment, a first spring 44 and a second spring 46 are provided between the mounting block 32 and the scale signal receiver 34, which can provide a bias force that presses the scale signal receiver onto the scale 22 via bearings. A third spring 48 is also fixed to the mounting block 32 and the scale signal receiver 34.

[0032] In the apparatus shown in Figure 1, it will be understood that the relationship between the scale and the scale signal receiver can be fixed in a first direction by springs 44, 46 that press the scale signal receiver 34 against the scale 22. Diagnostic information regarding the detected scale signal (e.g., disclosed in International Publication 2017 / 093738) indicates a change in the relationship between the scale and the scale signal receiver and can be used to detect damage or wear to the scale and / or scale signal receiver. If damage or wear is detected, the encoder (or part thereof) may be replaced to ensure accurate measurement.

[0033] Replacing an encoder or its components can mean the machine will be unusable for an extended period, and will incur costs for purchasing and installing replacement parts.

[0034] Figure 3 schematically shows a first embodiment of the encoder 100 according to the present invention. The embodiment shown in Figure 3 is similar to the embodiments shown in Figures 1 and 2 and schematically includes a scale 202 extending in the scale measurement direction 208 and a read head 300. The read head 300 includes a mounting block 302 and a scale signal receiving unit 304. The read head 300 is movable relative to the scale 202 in direction 307 (substantially parallel to the direction 208 in which the scale 202 extends), which can be achieved by mounting the scale 202 to a first part of the machine and the read head 300 to a second part of the machine (via the mounting block 302), where the first and second parts of the machine move relative to each other. The guided scale signal receiver 304 is mounted to the mounting block via a portion 309 of the mounting block, which extends into the scale signal receiver 304 and is rotatably mounted to the scale signal receiver 304 by point 400 and a first spring 404, a second spring 406, and a third spring 408.

[0035] In the embodiment shown in Figure 3, when in use and when set up, the scale signal receiving unit 304 contacts the scale 202 via a bearing (similar to the bearing 41 in Figure 1(b)). The scale signal receiving unit 304 is configured to be relatively movable relative to the scale 202 in the scale measurement direction 208, while its relative movement to the scale 202 is constrained in other directions. This ensures that the positional relationship between the scale 202 and the scale signal receiving unit 304 remains substantially constant in directions other than the scale measurement direction 208. The pivot 400 and the first spring 404, second spring 406, and third spring 408 allow the scale signal receiving unit 304 to move relative to the mounting block 302.

[0036] When the embodiment shown in Figure 3 is mounted on a machine (with the encoder set up), the scale 202 is mounted on a first part of the machine, and the scale 202 may be placed in a protective housing (not shown), which is mounted on the first part of the machine. The mounting block 302 is fixed to a second part of the machine. After fixing, the mounting block 302 and the scale signal receiver 304 have a specific relationship (depending on the relationship between the first and second parts of the machine and the method of fixing the scale signal receiver 304 and the mounting block 302). Figure 3 shows the distance d between the mounting block 302 and the scale signal receiver 304. If the mounting block 302 is closer to the scale 202 than the optimal distance, the first spring 404 and the second spring 406 exert force on the scale signal receiver 304, and as a result, the bearing of the scale signal receiver 304 (e.g., a bearing similar to the bearing 41 shown in Figure 1(b)) can exert an undesirably large force on the scale 202 (on the scale side where the mounting block 302 is located). This can increase scale wear. Conversely, if the mounting block 302 is located further than the optimal distance from the scale 202, the bearing may not make sufficient contact with the scale, causing the signal reaching the photodetector of the guided scale signal receiver to deviate from the expected signal, which can lead to errors due to the way the signal is interpreted.

[0037] In order for the guided scale signal receiver 304 to be optimally positioned relative to the scale 202 at all positions of the read head 300 along the scale 202, the mounting block 302 must be positioned close enough to the guided scale signal receiver 304 so as to ensure sufficient contact between the guided scale signal receiver 304 and the scale 202, without applying an undesirable force at all positions of the read head 300 along the scale 202. To achieve this, the direction 307 in which the read head 300 moves must be substantially parallel to the direction 208 in which the scale 202 extends. If directions 307 and 208 are not parallel, the distance between the mounting block 302 of the read head 300 and the guided scale signal receiver 304 will not be constant along the length of the scale 202. This results in a situation where, when the read head 300 is located at one end of the scale 202, the mounting block 302 is positioned closer to the guided scale signal receiver 304 than when the read head 300 is located at the other end of the scale 202. This can be described as the encoder having a "tight end" (mounting block 302 is relatively close to the guided scale signal receiver 304) and a "loose end" (mounting block 302 is relatively far from the guided signal receiver 304).

[0038] For the encoder 100 to operate optimally, the mounting block 302 should be positioned at a distance from the scale 202 such that the read head 300 is within the optimal range at all positions along the scale 202. This means that the distance d between the mounting block 302 and the guided scale signal receiver 304 is within the optimal range for all positions along the scale 202.

[0039] The embodiment shown in Figure 3 is provided with a device for measuring distance d so that the mounting block 302 can be positioned at an optimal distance from the guided scale signal receiver 304. In this embodiment, the distance measuring device for measuring distance d is a capacitive gap measuring device 410 located on the scale signal receiver 304. The capacitive gap measuring device 410 can determine and output information indicating the relationship between the mounting block 302 and the scale signal receiver 304. The lead head 300 is provided with a human-perceptible signal output device, which in this embodiment is in the form of an LED 420 located on the lead block 302. Based on the output from the capacitive gap measuring device 410, the LED 420 outputs a signal. In this embodiment, the LED 420 emits a first color when d is at or within the optimal value, a second color when d is less than the optimal distance (i.e., when the mounting block 302 is closer to the scale signal receiver 304 than the desired distance), and a third color when d is greater than the optimal distance (i.e., when the mounting block 302 is undesirably far from the scale signal receiver 304). This allows an operator setting up the encoder by mounting the scale 202 and the read head 300 to the first and second parts of the machine to easily identify whether the relationship between the mounting block 302 and the scale signal receiver 304 is maintained within the optimal range, regardless of the position of the read head 300 along the length of the scale 202, and thus contributes to reducing damage and wear.

[0040] Figure 4 schematically shows a second embodiment of the encoder 100 according to the present invention. The encoder shown in Figure 4 is structurally similar to the embodiment shown in Figure 3, and the same reference numerals are used in both embodiments. Figure 4 shows that the first distance d1 is the distance between the mounting block 302 and the scale signal receiver 304 near the first spring 404, and the second distance d2 is the distance between the mounting block 302 and the scale signal receiver 304 near the second spring 406.

[0041] When attaching the scale 202 and the mounting block 302 to the first and second parts of the machine, the mounting block 302 may be mounted at an angle to the measurement direction of the scale, for example, so that one end of the mounting block 302 is closer to the scale 202 than the other end. This can cause the first distance d1 and the second distance d2 to be different. For example, if d1 is less than d2, the bias force that the first spring 404 exerts on the scale signal receiver 304 against the scale 202 will be greater than the bias force that the second spring 406 exerts on the scale signal receiver 304 against the scale 202. This can occur even when the average distance between the scale signal receiver 304 and the mounting block 302 is within the optimal range. It may be undesirable for the bias force supplied by either the first spring 404 or the second spring 406 to be too large, because this could lead to the bearing of the scale signal receiver 304 applying excessive force to the scale 202 (near the first spring 404 in this example), which could increase damage and wear to the bearing and / or the scale 202, thus shortening the lifespan of the encoder.

[0042] The embodiment shown in Figure 4 includes a first capacitive gap measuring device 412 and a second capacitive gap measuring device 414. The first capacitive gap measuring device 412 measures the distance between the mounting block 302 and the scale signal receiver 304 near the first spring 404, and the second capacitive gap measuring device 414 measures the distance between the mounting block 302 and the scale signal receiver 304 near the second spring 406. Using the outputs of the first and second capacitive gap measuring devices 412 and 414, it is possible to determine and output information that may be diagnostic information indicating the relationship between the mounting block 302 and the scale signal receiver 304. In the embodiment shown in Figure 4, the LED 420 outputs a first signal when d1 is greater than d2 and the difference exceeds a threshold, a second signal when d1 is less than d2 and the difference exceeds a threshold (which may be the same or a different value as the value used for the first signal), and a third signal when the difference between d1 and d2 does not exceed a threshold (which may be the same value or set of values ​​as the values ​​used for the first and second signals). The LED 420 can also be used to output a signal indicating the average distance between the mounting block 302 and the scale signal receiver 304.

[0043] The embodiments of the first 412 and second 414 volume gap measuring devices shown in Figure 4 are spaced apart in the elongated scale direction 208, so that the mounting blocks 302 are pitched relative to the scale 202 (i.e., in the direction 208 and d -1In other embodiments, it is possible to confirm that rotation (rotation around an axis perpendicular to the direction) is occurring, and alternative spacing arrangements of the first capacitive gap measuring device 412 and the second capacitive gap measuring device 414 are envisioned. For example, the first capacitive gap measuring device 412 and the second capacitive gap measuring device 414 may be spaced apart along directions perpendicular to direction 208 and d1. Such an arrangement makes it possible to determine whether the mounting block 302 is rolling relative to the scale 202 (i.e., rotating around an axis parallel to direction 208). In other embodiments, the first capacitive gap measuring device 412 and the second capacitive gap measuring device 414 may be spaced apart in both directions parallel to direction 208 and directions perpendicular to direction 208 and d1.

[0044] In the embodiments shown in Figures 3 and 4, the capacitive gap measuring device is mounted on the scale signal receiver, but this is not necessarily required. In other embodiments, one (or more) capacitive gap measuring devices may be positioned on the mounting block 302 to perform the same function of measuring the distance d (or d1 and d2) between the mounting block 302 and the scale signal receiver. In yet another embodiment, it is not necessary to use a capacitive gap measuring device, and the distance d (or d1 and d -2 To provide information regarding the first spring 404 or the second spring 406 (or both the first spring 404 and the second spring 406), strain gauges (one or more) associated with the first spring 404 or the second spring 406 may be used.

[0045] Figure 5 schematically shows a third embodiment of the encoder 100 according to the present invention. Figure 5 shares some structural features with the embodiments shown in Figures 3 and 4, and the same reference numerals are used in both embodiments.

[0046] In the embodiment shown in Figure 5, the mounting block 302 is connected to the scale signal receiver 304 via an articulated link 500. In this embodiment, the articulated link is shown as a scissor mechanism. The articulated link 500 in the illustrated scissor mechanism includes a first rod 502 and a second rod 504, which are rotatably attached to the mounting block 302 at points 506 and 510, respectively. The articulated link 500 further includes a first rod 503 and a second rod 505, which are rotatably attached to the scale signal receiver 304 at points 512 and 508, respectively. Rods 502 and 503 are rotatably connected to each other at point 514. Rods 504 and 505 are rotatably connected to each other at point 515, and the articulated link 500 allows the scale signal receiver 304 to move relative to each other as the scale signal receiver 304 moves in the measuring direction 208 and the mounting block 302 moves in the direction 307, thereby allowing the distance between the mounting block 302 and the scale signal receiver 304, perpendicular to the plane on which the scale 202 extends, to be varied in order to reduce or prevent damage to the scale and / or scale signal receiver 304. The embodiment in Figure 5 may include a biasing mechanism (not shown) for pressing the guided scale signal receiver 304 against the scale 202. This biasing mechanism may include a spring as part of the articulated mechanism 500. For example, the biasing mechanism may include a first torsion spring located at point 514 and a second torsion spring located at point 515, wherein the first 514 torsion spring and the second 515 torsion spring may be configured to bias the mounting block 302 and the guided scale signal receiver 304 apart from each other.

[0047] The embodiment in Figure 5 further includes an angle encoder (often called a rotary encoder) positioned at point 506 to measure the angle 516 formed between the rod 502 and the mounting block 302. From the angle 516, the distance d between the scale signal receiver 304 and the mounting block can be derived. In the illustrated embodiment, a second angle encoder is provided at 510 to measure the angle 518 between the mounting block 302 and the second rod 504. This makes it possible to measure any inclination the mounting block 302 has with respect to the scale measurement direction 208.

[0048] In the embodiment shown in Figure 5, a first angle encoder is provided at point 506 and a second angle encoder at position 510. However, in other embodiments, the distance d can be calculated by providing an angle encoder at any one of positions 506, 508, 510, 512, 514, or 515. In yet another embodiment, placing the first angle encoder at any of positions 506, 512, or 514 and the second angle encoder at any of positions 508, 510, or 515 makes it possible to measure the distance d and any inclination of the mounting block 302 with respect to the scale measurement direction 208.

[0049] The embodiments shown in Figures 3, 4, and 5 show a single LED 420 that outputs a signal indicating the relationship between the mounting block 302 and the scale signal receiver 304, but this is not necessarily required. In another embodiment, two or more LEDs can be used to provide information about the distance between the mounting block 302 and the scale signal receiver 304, and the inclination of the mounting block 302 relative to the scale signal receiver (based on a discrepancy in the information regarding distances d1 and d2). In yet another embodiment, the signal does not need to be provided by an LED, but may be an auditory or tactile signal.

[0050] The embodiments described above directly determine information indicating the relationship between the mounting block and the guided scale signal receiver (for example, by measuring at least one distance between the mounting block and the guided scale signal receiver, or by measuring the angle of the linkage mechanism), but the present invention is not limited to such embodiments, and for example, the relationship between the mounting block and the guided signal receiver may be determined indirectly. For example, in some embodiments, the scale is provided in a protective housing, and in such embodiments, the relationship between the scale and the protective housing is known. The relationship between the guide signal receiver and the scale is also known by the guiding characteristics of the guide signal receiver, so the relationship between the mounting block and the guide signal receiver can be determined indirectly. In some embodiments, the relationship between the mounting block and the protective housing is determined using one or more capacitive distance sensors (mountable on the mounting block), thereby determining information indicating the relationship between the mounting block and the scale signal receiver, and thus the relationship between the mounting block and the scale signal receiver can be determined indirectly. In yet another embodiment, an encoder is configured to detect the relationship between the mounting block and the scale, and this information can be used to determine the relationship between the mounting block and the scale signal receiver. For example, by providing one or more capacitive distance sensors on the mounting block and measuring the distance between the mounting block and the scale, the relationship between the mounting block and the scale signal receiver can be indirectly determined.

Claims

1. An encoder module for mounting on a machine to measure the relative displacement of a first part and a second part of the machine, comprising a scale and a read head having a guided scale signal receiver coupled to a mount, and configured to determine and output information indicating the relationship between the mount and the guided scale signal receiver.

2. The encoder module according to claim 1, wherein the information relating the relationship between the mount and the guided scale signal receiver comprises information relating the relationship between the mount and the guided scale signal receiver obtained directly and / or indirectly.

3. The encoder module according to claim 1 or 2, wherein the read head is configured to determine and output the information.

4. The encoder module according to any one of claims 1 to 3, comprising at least one output device for outputting the information in the form of a human-perceptible signal.

5. The encoder module according to claim 4, wherein the output device comprises a visual output device.

6. The encoder module according to claim 4, wherein the output device comprises an acoustic output device.

7. The encoder module according to any one of claims 4 to 6, wherein the at least one output device is provided on the read head and additionally on a mount.

8. The encoder module according to any one of claims 1 to 7, comprising an integrated protective housing that encloses at least the scale and at least a portion of the scale signal receiver.

9. The encoder module according to claim 8, referencing any one of claims 4 to 7, wherein the mount comprises a mounting portion on the outside of the protective housing for attaching the mount to either a first movable part or a second movable part of the machine, and the output device is provided on the mount.

10. The encoder module according to claim 8, which is dependent on any one of claims 4 to 7, wherein the at least one output device is provided on the protective housing.

11. The encoder module according to any one of claims 8 to 10, wherein the protective housing comprises at least one compliant seal from which the read head can extend, enabling the guided signal receiver to be mounted on part of the machine.

12. The encoder module according to any one of claims 1 to 11, wherein the scale comprises a rotary scale.

13. An encoder module according to any one of claims 1 to 12, comprising an optical scale and a read head.

14. A machine comprising an encoder module according to any one of claims 1 to 13.

15. A method for setting up an encoder module for measuring the relative positions of two relatively movable parts of a machine in a first degree of freedom, wherein the encoder module comprises a scale and a read head having a guided scale signal receiver coupled to a mount, the encoder module is configured to determine and output information, and the method comprises using the information to determine whether the scale signal receiver and the mount are in a desired relative positional relationship in at least one degree of freedom other than the first degree of freedom.

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